Multifunctional integrated electrochromic device by p-n conductive polymers for self-powered smart windows and miniaturized spectrometers

Domain: physics
Published: 2025-12-22
Editorial outcome: minor_revision

Abstract
Electrochromic devices enable dynamic modulation of light and heat, yet their broader adoption is hindered by limited color tunability, slow switching kinetics, and low coloration efficiency. Here, we present a complementary organic electrochromic device that addresses these challenges by employing dual conductive polymers: poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) and poly(benzodifurandione). The resulting device delivers exceptional performance, featuring a high optical contrast of 51% at 570 nm, ultrafast switching speeds (0.17/0.36 s for coloration/bleaching), a record-high coloration efficiency (1688 cm2 C⁻1 at 550 nm), and excellent cycling stability over 10,000 cycles. By integrating the device with a semitransparent organic solar cell, we realize a fully self-powered smart window with reducing indoor temperatures by 7 °C. Furthermore, coupling the electrochromic filter with a 4 × 4 organic photodetector array featuring on-chip Fabry–Pérot cavities enables a miniaturized spectrometer with 7.2 nm spectral resolution. This multifunctional electrochromic platform seamlessly bridges smart-window technology and spectral sensing, paving the way for energy-efficient, and compact optoelectronic systems.

Introduction
Electrochromic devices (ECDs) have emerged as a promising class of dynamic optical components capable of reversibly modulating light transmission and absorption in response to an applied electrical bias1–4. By enabling real-time control over visible and near-infrared (NIR) light, ECDs offer a compelling solution for applications that demand adaptive light regulation, including smart building exteriors5, energy-saving windows6–8, optical modulators3,9,10, and wearable electronics11,12. Their low power consumption, solid-state nature, and scalability further support their integration into modern multifunctional systems without the need for mechanical components3,13–15.

Despite their promise, the widespread implementation of ECDs remains constrained by limitations in material performance and device design. Inorganic electrochromic materials, particularly tungsten oxide (WO₃), have long served as the cornerstone of ECD technologies due to their stability and relatively well-understood switching behavior16,17. However, they are inherently limited by sluggish response speeds, restricted color tunability, high processing temperatures, and mechanical rigidity4,18. These shortcomings hinder their use in flexible, large-area, or energy-autonomous systems. Even with ongoing efforts in structural engineering1, doping strategies19, and electrolyte optimization20–22, state-of-the-art inorganic ECDs typically exhibit switching times on the order of seconds, moderate coloration efficiencies (<400 cm2 C⁻1), and noticeable degradation after several thousand operational cycles23–27.

Organic electrochromic devices (OECDs) offer a promising alternative, leveraging the structural tunability of organic semiconductors to achieve a broad spectral tunability, high coloration efficiencies, and compatibility with low-temperature, solution-based fabrication methods28–31. Their lightweight, flexible nature also makes them well-suited for integration into conformal and portable systems. Moreover, enhanced ionic mobility and the ability to engineer symmetric charge storage layers provide pathways toward faster switching and improved cycling stability32. However, OECDs are still constrained by trade-offs among optical contrast, switching speed, operating voltage range, and long-term stability, which limit their broader functional deployment.

To address these challenges, we present a complementary OECD that integrates two electrochemically compatible conductive polymers, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and poly(benzodifurandione) (PBFDO)33–35, into a high-performance bilayer architecture. This device exhibits a unique combination of key performance metrics, including high optical contrast (51% at 570 nm), ultrafast switching speeds (0.17 s for coloration and 0.36 s for bleaching), exceptional coloration efficiency (1688 cm2 C⁻1 at 550 nm), and robust cycling stability over 10,000 cycles at ±1 V with negligible degradation. The flexible quasi-solid-state gel through in-situ polymerization eliminates the need for liquid electrolyte and enables scalable fabrication on both large-area (20 × 20 cm2) and flexible (10 × 10 cm2) substrates. Integrated into a vertically stacked smart window (Fig. 1a), the OECD is powered by a semitransparent organic solar cell (ST-OSC) module (active area 100 cm2), enabling autonomous switching under standard solar illumination. This self-powered system reduces interior temperatures by up to 7 °C under simulated sunlight, highlighting its potential for energy-efficient, solar-responsive architecture.

Beyond building-scale applications, the voltage-tunable optical properties of the OECD enable new possibilities in compact and reconfigurable optical systems. With the growing demand for programmable alternatives to bulky components like prisms and gratings36–43, electrochromic materials, with their low power consumption, electrical tunability, and compactness, are well-suited for this role2,3. As shown in Fig. 1b, leveraging the high performance of our OECD architecture, we develop a microscale organic electrochromic spectrometer (OECS) featuring 16 pixels, each 4 mm2 and addressable across 14 discrete redox states. This configuration enables precise spectral filtering and accurate broadband light reconstruction with a mean squared error (MSE) as low as 0.001. Integrated with a 4 × 4 static Fabry Pérot (FP) cavity array and high-sensitivity organic photodetectors (OPDs) (with peak detectivity up to 1.6 × 1012 Jones), the OECS achieves a spectral resolution of 7.2 nm and over 99% classification accuracy across diverse organic solvents.

This work presents two applications of OECDs, a self-powered smart window and a miniaturized spectrometer, both based on voltage-controlled modulation of optical properties. The smart window enables adaptive light regulation for energy-efficient buildings, while the spectrometer achieves precise light filtering and spectral detection in a compact, portable format. Together, these results demonstrate a scalable electrochromic platform that bridges large-area energy management with high-resolution optical sensing, positioning OECDs as a foundational technology for next-generation adaptive optoelectronics and real-time environmental monitoring.

Results
Self-powered smart window

Device architecture and optimization of electrochromic components. To enable efficient light and heat modulation in the self-powered smart window, we first developed and optimized the underlying OECD, adopting a five-layer configuration: ITO/PEDOT:PSS/gel electrolyte/PBFDO/ITO (Fig. 2a). The two outer ITO layers function as transparent electrodes, while PEDOT:PSS and PBFDO serve as the cathodic and anodic electrochromic layers, respectively. A UV-curable ion-conducting gel (PC+PEGDA+LiTFSI+1173 photoinitiator) is used as the intermediate quasi-solid electrolyte, facilitating reversible redox switching. Cross-sectional scanning electron microscopy (SEM) analysis (Fig. 2a) revealed well-defined layer thicknesses of 132 nm for PEDOT:PSS, and 116 nm for PBFDO, with field emission SEM (FESEM) images confirming the formation of dense, homogeneous, and amorphous electrochromic layers (Supplementary Fig. 1). The molecular structures of PEDOT:PSS and PBFDO are shown in Fig. 2b. As shown in Fig. 2c, both materials exhibit high transmittance in their bleached states, with minimal absorption near 506 nm and 574 nm, respectively, wavelengths close to the peak sensitivity (~550 nm) of human eye44. This spectral alignment ensures effective daylight modulation while maintaining visual comfort, making them well-suited for architectural applications.

To achieve uniform and defect-free films, the blade-coating process was systematically optimized. Incorporating FS-30 surfactant into the PEDOT:PSS precursor improved substrate wetting and minimized edge shrinkage during high-temperature curing (Supplementary Fig. 2). Similarly, BYK-333 was added to the PBFDO solution to enhance film uniformity by suppressing dewetting behavior (Supplementary Fig. 3). However, elevated curing temperatures (>60 °C) led to morphological defects due to rapid solvent evaporation (Supplementary Fig. 4). Electrical measurements identified 60 °C under ambient conditions as the optimal annealing temperature, yielding the highest conductivity of 1350 S cm⁻1 (Supplementary Fig. 5). Based on these findings, a curing protocol of 60 °C for 10 min was adopted for PBFDO layer. The thickness of the PBFDO layer was also tuned to balance optical transmittance and electrical conductivity. As shown in Fig. 2d and Supplementary Fig. 6, increasing the film thickness from 40 nm to 350 nm led to a monotonic decrease in visible–NIR transmittance, while the conductivity plateaued at 122 nm. An optimized range of 80–122 nm provided 60–70% transmittance at 550 nm and maintained high conductivity (~1351 S cm⁻1). Electrochromic performance at a ±2 V bias (Supplementary Fig. 7) showed that this thickness range delivered the highest optical modulation, with ΔTmax values reaching 51% at 570 nm.

The quasi-solid-state electrolyte was optimized for both ionic transport and film morphology. A cured thickness of 200 μm and a UV exposure time of 7 s resulted in high conductivity (Fig. 2e, f) and a robust, flexible ion-transport layer (Fig. 2g). The 10 × 10 cm2 flexible OECD showed only a 7% optical contrast loss after 5000 bending cycles. This composition provided a stable electrochemical environment while ensuring conformal contact with the adjacent electrochromic layers. Overall, these optimizations in material formulation, curing conditions, and structural dimensions collectively enabled high-performance electrochromic switching at low voltage, while ensuring compatibility with scalable fabrication processes and flexible substrates, laying a solid foundation for integration into the self-powered smart window system.

Electrochromic performance of the complementary device. To understand the intrinsic electrochromic behavior of each active material, we first examined PEDOT:PSS and PBFDO in half-cell configurations: PE-OECD (ITO/PEDOT:PSS/electrolyte/ITO) and PB-OECD (ITO/PBFDO/electrolyte/ITO). As shown in Supplementary Fig. 8a and Supplementary Fig. 9a, both devices exhibited moderate optical modulation, with transmittance changes (ΔT) of 14.9% at 612 nm and 13.6% at 694 nm, respectively. The PE-ECD underwent a reversible transition from doped (transparent) to undoped (light blue) states, accompanied by a lightness (L*) drop from 81.2 to 57.3 and a light blue hue (Supplementary Fig. 8b, c, Supplementary Fig. 10a and Supplementary Table 1). In contrast, the PB-ECD displayed a neutral gray-to-dark transition with a larger L* drop (80.8 to 41.3), but minimal chromatic shift (Supplementary Fig. 9b, c, Supplementary Fig. 10b and Supplementary Table 1). The reversible intercalation/deintercalation processes can be described as following equations:

PEDOT n+ ·xPSS ·(n-x)TFSI + nLi+ + ne⁻ ↔ PEDOT0 ·xPSS ·(n-x)TFSI ·nLi+ (1)

PBFDO n- ·xH+ ·(n-x)Li+ + nTFSI + ne⁻ ↔ PBFDO0 ·xH+ ·(n-x)Li+ ·nTFSI (2)

Both systems exhibited fast response times (~5 s–8 s) and decent coloration efficiencies of 128 and 123 cm2 C⁻1 at 550 nm (Supplementary Fig. 8d, e and Supplementary Fig. 9d, e). However, their cycling stability was poor, ΔT dropped below 2% within 200–300 cycles (Supplementary Figs. 8f, 9f), primarily due to unbalanced charge storage at the inert ITO counter electrodes, which led to irreversible electrochemical degradation20,45. In fact, even when employing extremely thin PEDOT:PSS and PBFDO films (~20 nm) as counter electrodes, the ECD performance is significantly enhanced (Supplementary Figs. 11, 12, and Supplementary Table 1).

Subsequently, we constructed full-cells, combining PEDOT:PSS (cathodic) and PBFDO (anodic) in a symmetric configuration. This complementary pairing allows for balanced ion intercalation and charge compensation during switching. As shown in Fig. 3a the optimized OECD achieves a ΔTmax of 51% at 570 nm, significantly outperforming the half-cells. The full-cell smart window also showed consistent and homogeneous switching behavior (Fig. 4a). Furthermore, a flexible 10 × 10 cm2 device retained stable electrochromic response under bending stress (Fig. 4b), underscoring its mechanical robustness and compatibility with flexible substrates.

In addition to visible light modulation, a key advantage of electrochromic windows lies in their ability to regulate solar heat gain, particularly in the NIR region. We therefore evaluated the thermal shielding performance of the smart window by converting the transmittance spectrum into solar-weighted irradiance profiles using AM1.5G conditions (Fig. 4d). At a bias of −0.5 V, the device effectively blocks 92.4% of NIR solar irradiance within the 780–2000 nm range. Even in the fully bleached state (at 2 V), the device still blocks 79.3% of NIR radiation (Supplementary Table 4). Furthermore, at a bias of −2 V, the device blocks 89.2% of total solar energy. Although the modulation of visible light reaches 40% at ±2 V, the NIR transmittance exhibits only a slight change of ~3%, enabling a “cool mode” operation that maintains indoor illumination while minimizing solar heating. The thermal shielding efficiency (SEheat) was calculated as the percentage of NIR heat solar irradiance blocked, using the following equations45:

SEheat = 100 - TE (5)

Itotal = ∫ φ(λ)dλ (6)

TE = (IT / Itotal) × 100% (7)

where IT and Itotal refer to the transmitted solar irradiance and total solar irradiance. φ(λ) is the transmitted solar irradiance spectrum at AM1.5G conditions. TE is transmission efficiency. Detailed results are summarized in Supplementary Table 5, revealing that SEheat values range from 78.7% to 92.1% across different voltage states, with most values exceeding 90%, thereby confirming the excellent heat-blocking performance of the OECD smart window.

To quantify the potential energy-saving benefits of our OECD smart windows, we conducted simulations using EnergyPlus software, incorporating both the measured optical properties and regional climate data. A standard office building (15 × 10 × 3 m3) with eight 3 × 2 m2 window panels was modeled (Supplementary Fig. 22 and Supplementary Table 6). Indoor temperature and lighting conditions were set to reflect real-world usage. As shown in Fig. 4e, the simulation framework captures seasonal variations in solar load and cooling demand. Taking Guangzhou as a representative subtropical city, the simulated annual cooling energy savings reached 228 MJ m⁻2 in the colored state (−2 V) and 171 MJ m⁻2 in the bleached state (2 V), compared to conventional low-emissivity (low-E) glass (Fig. 4f). Simulations across diverse global climates confirmed consistent energy savings, with up to 594 MJ m⁻2 savings in Brasília and a 50.9% reduction in annual cooling load in Reykjavík (Fig. 4g). The full simulation data are presented in Supplementary Table 7, collectively demonstrating the broad applicability of the OECD smart window across different environmental contexts.

ST-OSC powered smart windows. To further enhance the autonomy and practicality of the OECD system, we integrated it with an ST-OSC, creating a fully self-powered smart window. This integrated design eliminates the need for external power sources, enabling the system to dynamically regulate light and heat transmission in response to ambient sunlight. Figure 5a schematically illustrates the device architecture, where the ST-OSC serves dual roles: as a photovoltaic power supply and a spectral modulator, vertically stacked directly above the OECD in a compact monolithic structure. Upon illumination, the ST-OSC generates sufficient voltage to switch the OECD between its bleached and colored states, ensuring seamless autonomous operation.

The ST-OSC features an ITO/PEDOT:PSS/bulk heterojunction (BHJ)/PNDIT-F3N/Ag/MoOx structure, with a ternary BHJ active layer comprising PTzBI-Cl and BTR-Cl donors, and DT-Y6 acceptor53. Figure 5b, c present the current density–voltage (J–V) characteristics, external quantum efficiency (EQE), and transmittance spectra for devices with varied silver (Ag) electrode thicknesses. Increasing Ag thickness from 10 nm to 30 nm boosts short-circuit current density (JSC) from 19.2 to 24.4 mA cm⁻2 but reduces average visible transmittance (AVT) from 27.9% to 7.1% (Supplementary Table 8). This trade-off arises from increased reflectivity in thicker Ag layers, which enhances charge generation but diminishes light utilization efficiency (LUE). To mitigate this trade-off, we introduced a high-refractive-index MoOx antireflection coating atop the Ag layer. Compared to the 15 nm Ag-only device, the MoOx-coated device exhibits significantly improved visible transmittance with minimal losses in JSC (0.27 mA cm⁻2) and EQE (0.22%), representing a favorable compromise (Fig. 5b, c and Supplementary Table 8). The MoOx layer effectively suppresses reflection in the visible range while maintaining efficient charge extraction and spectral absorption. The optimized configuration, 15 nm Ag with 30 nm MoOx, achieves a maximum power conversion efficiency (PCE) of 12.97% and an LUE of 3.72. Colorimetric analysis (Fig. 5d) reveals that increasing Ag thickness shifts device appearance from white to blue, with the optimized device delivering a high color rendering index (CRI) of 86.4 and CIE chromaticity coordinates of (0.2376, 0.2700) (Supplementary Table 8). Based on the optimized small-area device, we fabricated a large-area ST-OSC module (active area 100 cm2) to power an OECD of matching size. As shown in Fig. 5e and Supplementary Table 9, the module exhibits a VOC of 10.06 V, JSC of 1.31 mA cm⁻2, PCE of 6.72%, AVT of 33.7% (Supplementary Fig. 23), and LUE of 2.26, confirming its capability to effectively drive the OECD. The integrated system transitions from a light-blue transparent state to a dark-blue colored state under illumination (Supplementary Fig. 24 and Supplementary Movie 1 and 2), demonstrating functional synergy.

Finally, a scaled-down model house experiment was conducted to evaluate the system thermal regulation capabilities under realistic conditions (Fig. 5f). The interior temperatures recorded were 33 °C without any device, 30.1 °C with the ST-OSC alone, and 26 °C with the integrated ST-OSC–OECD system, demonstrating significant improvements in thermal insulation. This cooling effect results from the combined contributions of the high infrared reflectance of the ST-OSC (IRR=75.4%)53 and the strong suppression of NIR solar transmittance in the colored state OECD. Collectively, these results highlight the feasibility of a fully self-powered, energy-autonomous smart window system that dynamically modulates light and heat to enhance indoor comfort and reduce building energy consumption. By integrating the OECD with a high-efficiency ST-OSC, the system autonomously controls optical transmission while lowering indoor temperature, underscoring its potential for large-scale, sustainable deployment.

On-chip organic electrochromic spectrometer (OECS)

Building on the scalability, tunable optics, and self-powered operation demonstrated in OECD-based smart windows, we translate the platform into chip-scale, voltage-programmable spectrometers. By monolithically integrating electrochromic filters with high-sensitivity OPDs, these devices provide reconfigurable spectral filtering and computational reconstruction. This transition from meter-scale dynamic windows to millimeter-scale photonics sensors underscores the versatility and cross-scale adaptability of the PEDOT:PSS–PBFDO electrochromic platform.

Working principle of the OECS. The OECS operates via a hybrid dual-mode modulation scheme. Co2V, while fine spectral resolution is obtained by incrementally addressing 14 discrete voltages between −2 V and 2 V. The resulting photocurrent Inm at pixel m at bias voltage n follow the integral expression,

Inm = ∫ λm Tn(λ) × R(λ) × S(λ)dλ (8)

where Tn(λ) the voltage-dependent transmittance of the electrochromic pixel, R(λ) the wavelength-dependent responsivity of the OPD, and S(λ) is the unknown incident light spectrum. With this forward model and a library of calibrated transmission spectra, the input spectrum can be reconstructed using computational inversion techniques. The responsivity calibration of the OPDs is shown in Supplementary Fig. 25. As illustrated in Fig. 6a, the OECS leverages a hybrid modulation strategy that combines broadband, voltage-tunable absorption from the electrochromic layer with pixel-specific static filtering from integrated FP cavities. The FP cavity is nanometer-scale, eliminating the need for additional optical components and enabling a compact all-solid-state spectral device. Each OECD pixel contains an Ag-based FP cavity with a tunable spacer layer. Figure 6b displays the 175 nm spacer layer electric field intensity and the operational range spans 50–425 nm. To validate the microcavity effect, additional TMM simulations were performed across different spacer thicknesses. The results show clear resonance peaks whose positions and intensities shift consistently with spacer variations, confirming tunable spectral selectivity of the FP cavities (Supplementary Fig. 26). The complex refractive indices of each material layer were extracted and used in transfer matrix method (TMM) simulations (Supplementary Fig. 27)54. Figure 6c presents the normalized responsivity of the OPD after FP cavities processing, as the spacer layer thickness varies linearly from 0 nm to 450 nm. FP cavities introduce sharp resonance peaks within the 380–1180 nm range, enhancing spectral discrimination and reducing crosstalk. The OPDs adopt a n–i–p architecture: ITO/ZnO/PCE-10:COTIC-4F:Y6/MoOx/Ag, optimized for broadband responsivity55. The structural relationship between the OECD and the FP cavities is illustrated in Supplementary Fig. 28. All 16 pixels in the OPD array exhibit uniform dark current densities on the order of 10⁻10 A cm⁻2 at zero bias (Fig. 6d), demonstrating excellent pixel uniformity. The measured noise current spectra (Fig. 6e) show flat noise characteristics over the 20–50 Hz range, with an average noise density of 6.9 × 10⁻15 A Hz⁻1/2. The specific detectivity (D*) was calculated using the standard formulation56:

D* = (R × AΔf^0.5) / (inose × Δf^0.5) = (EQE × AΔf^0.5) / (hci × inose) (9)

where q is the electron charge, A is the effective area (1.1 mm2), and Δf is the electrical bandwidth (1 Hz). The OPD achieved a peak D* of 1.6 × 1012 Jones (Fig. 6f), placing it among the best-performing organic devices in this class. In addition, Supplementary Fig. 29 shows the OPDs exhibit a fast response with rise and fall times of 14.9 μs and 15.2 μs, respectively, and a −3 dB cutoff bandwidth (f−3dB) of 101 kHz (Fig. 6g). The linear dynamic range (LDR), calculated as refs. 57, 58:

LDR = 20 log10 (Imax / Imin) (10)

where Imax is the maximum unsaturated photocurrent and Imin is the noise-limited detection threshold. The OPD achieves a broad LDR of 152 dB, indicating its ability to resolve optical signals across a wide intensity range (Fig. 6h)59–61. Figure 6i exhibits a distinct transmission spectrum as a function of applied voltages, providing a rich library of optical fingerprints for multi-dimensional sampling. This synergy between dynamic (EC) and static (FP cavity) filtering enables accurate spectrum reconstruction from a small number of physical pixels. Fabricated FP cavity and the monolithic OPD array are shown in Supplementary Fig. 30.

Voltage-encoded multidimensional spectral sampling and reconstruction. Different pixels measured at 14 bias voltages exhibit distinct EQE responses (Supplementary Fig. 31), enabling sufficient spectral information for reconstructive spectroscopy. Building upon the hybrid dual-mode modulation strategy and calibrated responsivity matrix Rn(λ), we implemented computational spectral reconstruction to evaluate the practical performance of the on-chip OECS under diverse illumination conditions (Fig. 7). This assessment encompasses both narrowband and broadband light inputs, showcasing high spectral resolution, reconstruction accuracy, and adaptability of the system.

We first validated the reconstruction accuracy under quasi-monochromatic illumination (3 nm bandwidth) spanning the 300–1200 nm range. As shown in Fig. 7a, the reconstructed spectra exhibit excellent agreement with those measured by a commercial grating spectrometer, demonstrating precise recovery of both peak positions and relative intensities. This confirms the effectiveness of our calibrated forward model across a broad spectral range.

To evaluate spectral resolution, we tested the ability to distinguish closely spaced wavelengths of the OECS. As shown in Fig. 7b, two peaks centered near 620 nm and separated by just 7.2 nm were clearly resolved. Further testing with 1 nm-spaced peaks in the NIR range (920–930 nm, Fig. 7c) yielded a mean deviation of only 0.29 nm between reconstructed and reference spectra, highlighting the high-resolution capability of the system even in the NIR range. We then assessed reconstruction performance for broadband light sources. For single-peak spectra such as filtered LED emissions, the OECS accurately reproduced the full profile (Fig. 7d). However, reconstructing complex broadband spectra remains a fundamental challenge for miniaturized systems62, particularly when relying on single-pixel or sequentially tuned devices due to their limited encoding diversity. To investigate this limitation, we compared the reconstruction fidelity between two architectures: a single-pixel OECD device and a multi-pixel OECS with integrated FP cavities. As shown in Fig. 7e, the single OECD (OECD-only), despite voltage tunability, exhibited poor reconstruction accuracy due to low-dimensional spectral encoding and a lack of spatial or spectral orthogonality. In contrast, the hybrid OECS (OECD+FP cavity array) substantially improved reconstruction quality, accurately recovering complex LED-filtered spectra as shown in Fig. 7f. This enhancement arises from the hybrid device capacity for parallel, multi-voltage, and spectrally selective sampling, enabling high-dimensional encoding across the array.

To quantify the effect of sampling dimensionality, we examined reconstruction error as a function of applied voltage steps. As shown in Fig. 7g, increasing the number of sampling voltages significantly reduced the MSE. With more than four voltages, the MSE dropped below 0.001, underscoring the importance of dense voltage sampling in enhancing reconstruction fidelity. The reduction in MSE with multiple voltage steps arises from enhanced spectral encoding. Each voltage slightly shifts the FP cavity resonance, causing a single OPD to produce distinct responses. Correlation analysis of a representative OPD (Supplementary Fig. 32) shows that additional voltage steps improve response distinguishability, providing richer measurement information for the reconstruction algorithm and directly lowering the MSE. These results clearly demonstrate that transitioning from single-pixel to array-based hybrid modulation not only improves resolution and accuracy but also enables robust, high-throughput spectral analysis in compact form factors. Using 14 voltage-modulated cavity states as sampling points, the spectrometer maintains <0.005 MSE in spectrum reconstruction even when 20% Gaussian white noise is added (Supplementary Fig. 33). Overall, the OECS combines active voltage-controlled filtering, static FP cavity selection, and computational inversion to deliver high-resolution, miniaturized spectrometry, a capability essential for next-generation portable sensing and imaging systems.

Application of OECS in material identification. To demonstrate the practical utility of the on-chip OECS beyond laboratory spectral reconstruction, we explored its application in real-world chemical analysis. Specifically, we focused on material composition identification via absorption spectroscopy, a standard analytical technique typically dependent on bulky, high-cost instruments. By leveraging the miniaturized form factor of OECS, reconfigurable spectral sampling, and broad operating range, we developed a compact transmission-mode setup for broadband absorption fingerprinting of organic materials.

As shown in Fig. 8a, the experimental setup comprises a broadband micro-LED light source, a cuvette containing either the sample or air (reference), and a narrow-angle engineered diffuser was incorporated to homogenize the angular distribution of the incident light, followed sequentially by the OECS. By maintaining near-normal incidence across all FP cavities, the diffuser ensures a consistent spectral baseline without significantly broadening the FP resonance peaks, thus preserving the intrinsic spectral resolution critical for accurate reconstruction. Figure 8b shows the OECS chip and the chip in a metal-encapsulated module for measurement. For each measurement, the device captured photocurrent responses corresponding to the sample spectrum Ssample(λ) and reference spectrum Sref(λ). These signals were then reconstructed into full spectra using the pre-calibrated responsivity matrix Rn(λ). The assumption of negligible sample reflectance, analogous to conventional UV–Vis–NIR spectrometry, allows the transmittance T(λ) and absorbance A(λ) to be determined via the Beer–Lambert law63:

T(λ) = Ssample(λ) / Sref(λ) (11)

A(λ) = -log10(T) = log10(1/T) (12)

To validate the performance, we measured the absorption spectra of four common organic dye solutions (10 mg mL−1), each with similar visible appearance but distinct molecular signatures (Fig. 8c). As shown in Fig. 8d, the reconstructed absorbance spectra from the OECS closely match those obtained using a commercial grating spectrometer, with accurate peak positions and relative intensities, demonstrating high-fidelity spectroscopic capability. As a proof-of-concept for material classification, we tested the ability of our OECS to differentiate among the four dyes, despite their partially overlapping absorption bands. Thank to the high spectral resolution and encoding diversity, the OECS successfully resolved subtle spectral differences and enabled unambiguous identification of each material. As shown in Fig. 8e, a classification model based on the reconstructed spectra achieved prediction accuracy exceeding 99%, confirming the system potential for reliable, compact, and cost-effective optical analysis in portable settings.

Methods
Materials
All chemical reagents used in this study were of analytical grade and applied without further purification. PBFDO was sourced from Jurong Optoelectronic Materials Technology Co., Ltd. PEDOT:PSS (PH1000) was obtained from Heraeus Co., Ltd. Propylene carbonate (PC), Lithium Bis(trifluoromethanesulfonyl)imide (LiTFSI) and 2-Hydroxy-2-methyl-1-phenylpropan-1-one (1173 photoinitiator) were purchased from Energy Chemical Co., Ltd. Poly(ethylene glycol) diacrylate (PEGDA) was purchased from Aladdin Co., Ltd. Polyether-modified polydimethylsiloxane (BYK-333) was purchased from BYK Co., Ltd. Fluorosurfactant (FS-30) was purchased from Chemours Co., Ltd. ITO glasses (10 Ω Sq−1) were purchased from Foshan Jingjiexin Glass Co., Ltd. The OPD array fabrication employed commercially available semiconductor materials, including the donor polymer PCE-10 and the non-fullerene acceptors COTIC-4F and Y6, which were procured from established materials suppliers (1-Material Inc., Solarmer Materials Inc., Macklin Biochemical Technology Co., and Dongguan Volt Ampere Photoelectric Technology Co., Ltd.).

Preparation of electrochromic film and electrolyte
ITO-coated glass substrates were sequentially cleaned via ultrasonication in soap solution, deionized water, acetone, and isopropanol, each for 15 min, to ensure a pristine surface. After drying under a nitrogen stream, the substrates were treated with oxygen plasma for 20 min to enhance surface hydrophilicity and adhesion. To prevent degradation of plasma-induced surface modifications, coating was performed immediately after treatment. Large-area EC films (5 cm × 5 cm, 10 cm × 10 cm, 11.5 cm × 12 cm, and 20 cm × 20 cm) were fabricated using a blade-coating and heat-curing method. For PEDOT:PSS film preparation, DMSO (5 wt%) and FS-30 (with a PEDOT:PSS-to-FS-30 dry weight ratio of 1:0.05) were sequentially added to PH1000 ink under magnetic stirring to enhance film conductivity and uniformity. The ink was then blade-coated using a four-sided applicator with a 50 μm gap. The wet films were subsequently dried in an oven at 110 °C for 5 min. To prepare PBFDO films, a commercially available PBFDO solution (12 mg mL−1 in DMAC) was diluted to 4 mg mL−1 with DMAC. BYK-33 was added (PBFDO-to-BYK-33 dry weight ratio of 1:0.1) under magnetic stirring to improve film uniformity. The mixture was blade-coated using a 100 μm applicator gap and dried at 60 °C for 10 min to yield the final film. Small-area EC films (1.5 cm × 1.5 cm) were fabricated using the same procedures, except spin coating was used instead of blade coating. Specifically, spin-coating parameters for PEDOT:PSS and PBFDO films were set to 1000 rpm for 10 s and 3000 rpm for 30 s, respectively. The electrolyte was prepared by stirring a solution containing PC (46.3 wt%), PEGDA (43.2 wt%), LiTFSI (2.2 wt%), and photoinitiator 1173 (8.3 wt%) until fully dissolved.

Material mechanism characterization
CV measurements were performed using a CHI660E electrochemical workstation. The electrochromic films (area 1.5 × 1 cm2) were characterized were carried out in a three electrode cell configuration using ITO/glass (for PEDOT:PSS films) or ITO/glass sheet (for PBFDO films) as the working electrode, Pt wire as the counter electrode, and Ag/AgCl as the reference electrode.

Fabrication of OECD
A double-sided conductive copper tape (thickness: 50 μm) was affixed to the four edges of the ITO/PBFDO glass substrate to minimize voltage drop. Notably, a segment of the copper tape was extended outward to facilitate connection with the external circuit. Subsequently, commercial 3M polyimide tapes with thicknesses of 50 μm and 100 μm were sequentially applied around the perimeter of the substrate, forming a final spacer gap of 200 μm. The gel electrolyte was then injected into the device using a syringe. Thereafter, the ITO/PEDOT glass was gently placed on top, and any trapped air bubbles were carefully expelled. The assembled device was secured with clips and cured under UV light for 7 s. For the half-cell configuration, the assembly procedure remained the same, except that the counter electrode was replaced with bare ITO glass.

Fabrication of ST-OSC
ITO-coated glass substrates were cleaned by ultrasonication in isopropanol, detergent solution, and deionized water, followed by a final isopropanol rinse. After drying at 80 °C for 2 h, substrates were treated with oxygen plasma (120 s) to enhance surface wettability. For the electron transport layer, a ZnO sol–gel precursor was prepared by dissolving zinc acetate (0.4 g) and ethanolamine (110 μL) in 2-methoxyethanol (4 mL), stirred at 55 °C for 10 h. The precursor was spin-coated (3300 rpm, 45 s) and annealed at 150 °C for 30 min to form a compact ZnO layer.

The photoactive layer comprised a ternary blend of PCE-10:COTIC-4F:Y6 (1:1.05:0.45 by weight) in chlorobenzene (25 mg mL⁻1) with 0.2 vol% 1-chloronaphthalene as a processing additive. After overnight stirring at 60 °C, the solution was spin-coated in two steps—800 rpm for 40 s (spreading) and 2000 rpm for 40 s (film formation)—yielding an active layer ~270 nm thick. A post-deposition annealing step at 100 °C for 10 min enhanced molecular ordering. Finally, a 10 nm organic hole transport layer and 100 nm Ag top electrode were thermally evaporated under high vacuum (9 × 10⁻7 Torr) to complete the device.

Fabrication of OECS
The FP cavity arrays were monolithically integrated with the OPD array via precision-controlled thermal evaporation. Each cavity consisted of two 13 nm Ag mirrors and an Alq₃ spacer layer, with the latter precisely tuned between 50–425 nm to define spectral response. A 7 nm MoOx interlayer was inserted to improve Ag mirror morphology and optical performance. Pixel-level patterning and nanometer-scale thickness control were achieved using custom shadow masks and real-time quartz crystal monitoring, allowing sequential, vacuum-integrated deposition without interruption. Devices were hermetically encapsulated using UV-cured epoxy and glass coverslips for environmental stability. Electrical interfacing was established through spring-loaded pogo pins, connecting the chip to a custom-designed PCB with integrated readout electronics. The complete assembly was housed in a compact mechanical enclosure, resulting in a fully portable miniature spectrometer system. For optical characterization, additional active layer solutions were prepared by dissolving PCE-10 (10 mg mL⁻1) and IEICO-4F (15 mg mL⁻1) in chlorobenzene, stirred at 60 °C for 2.5 hours, and deposited via optimized spin-coating protocols. This integrated fabrication strategy enables wafer-scale production of spectrally selective photodetector arrays, fully compatible with standard optoelectronic packaging, while eliminating alignment challenges typically associated with discrete optical components in miniaturized spectrometer systems.

Material and device characterization
The UV–Vis–NIR transmittance and absorption spectra of the OECD were measured using a UV-3600i Plus spectrophotometer. Polymer surface morphology was characterized via field emission scanning electron microscopy (FESEM, Merlin), while cross-sectional images were obtained using a SU8600 system. Cyclic stability was evaluated using an electrochromic device cyclic tester (KV-EC-7500, Kaivo, Zhuhai). Colorimetric properties in the CIEL*a*b* space were assessed with a Benchtop Grating Spectrophotometer (LS173, Linshang, Shenzhen), and CIE xy coordinates were measured using LCE Intelligent Detection Instrument (HP350C, Shuangse, Hangzhou). Electrical conductivity (σ) was calculated using the following formula:

σ = 1 / (Rs × t) (13)

where σ denotes the electrical conductivity, t is the film thickness measured by a profilometer, and Rs is the sheet resistance identified by a Four Probe Tester. The coloration efficiency (CE) at a given wavelength was determined by the following formula:

CE(λ) = ΔOD / Q = log(Tb/Tc) / Q (14)

where ΔOD represents the change in optical density, Q is the injected/extracted charge, and Tb and Tc refer to transmittance in the bleached and colored states, respectively. The gel electrolyte was UV-cured using a DH48S LED curing system (Deshengxing, Shenzhen). Chronoamperometry and chronocoulometry measurements were performed on a CHI660E electrochemical workstation. Dark J–V characteristics were recorded using a high-precision semiconductor parameter analyzer (PDA FS380 Pro, Platform Design Automation). EQE spectra were acquired using a custom-built system consisting of a stabilized halogen lamp (7IPT250B, SOFN Instruments), a low-noise current preamplifier (SR570, Stanford Research Systems), and a lock-in amplifier (SR830, Stanford Research Systems), with spectral calibration performed using reference Si and InGaAs PDs. Frequency response measurements employed a 1050 nm LED modulated by a function generator (AFG1062, Tektronix), and the transient photocurrent was captured using a 350 MHz digital oscilloscope (MDO3052, Tektronix). For LDR evaluation, the illumination intensity from the 1050 nm LED, driven by a Keithley 2450 Source Meter, was precisely modulated and measured using a calibrated optical power meter (1919-R, Newport) with a Si photodiode (818-UV/DB), while photocurrent was simultaneously recorded by the FS380 Pro analyzer. Reference spectral data of incident light were acquired with a high-end UV–Vis–NIR spectrometer (UV-3600, SHIMADZU). Quasi-monochromatic illumination was provided by a filtered broadband source, and complex spectra were generated using either a xenon arc lamp or a cold white LED, enabling comprehensive characterization across the visible to NIR range under controlled ambient conditions with appropriate light shielding.

Optical simulation
The optical characteristics of the Fabry-Pérot (FP) cavity were numerically modeled using the transfer matrix method (TMM), a rigorous computational technique for analyzing multilayer optical systems. The wavelength-dependent complex refractive index (ñ=n+ik) of the Alq₃ spacer layer, a key input for the simulation, was experimentally obtained via spectroscopic ellipsometry using a ME-L ellipsometer (Wuhan Eoptics Technology). This method enabled accurate extraction of both the refractive index (n) and extinction coefficient (k) across the relevant spectral range, facilitating precise modeling of light propagation and interference effects within the cavity. By combining first-principles optical calculations with experimentally validated material parameters, the simulation provides reliable predictions of the FP cavity’s resonant behavior and spectral response.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "The manuscript reports an all-solid-state complementary electrochromic device (OECD) based on PEDOT:PSS and PBFDO polymers, demonstrating self-powered smart windows and a miniaturized electrochromic spectrometer. The topic combines electrochromic functionality with organic photodetectors to achieve multifunctional adaptive optoelectronic systems. However, the manuscript currently suffers from logical inconsistencies and a lack of scientific rigor, with insufficient experimental justification. I therefore recommend rejection. Several critical aspects require clarification and additional evidence before the paper can be considered for publication elsewhere.\n1. The manuscript presents two applications of electrochromic materials—a self-powered smart window and a miniaturized spectrometer—but the logical connection between them is weak. As written, the two parts appear as independent studies rather than a coherent, unified work.\n2. In Figure 3g, the manuscript claims superior performance over both organic and inorganic electrochromic devices, attributing this to the symmetric redox interplay between PEDOT and PBFDO. However, this explanation is insufficient, lacking specific theoretical support or experimental validation, and therefore cannot be considered convincing. Since many traditional inorganic electrochromic systems also operate through symmetric redox reactions, the authors should provide a more detailed explanation—beyond simple charge balance—to clarify why their device outperforms established inorganic counterparts in both speed and efficiency.\n3. The claim of “excellent cycling stability” is questionable. Many electrochromic systems demonstrate stability beyond 20,000 cycles. Moreover, performance metrics are compared across inconsistent voltage ranges (e.g., Figure 3g optical contrast at ±2 V, stability at ±1 V). Fair benchmarking requires unified operating conditions.\n4. The manuscript reports transmittance at multiple, inconsistent wavelengths (506 nm, 550 nm, 574 nm, 694 nm), which undermines the scientific rigor of the comparisons. Such inconsistency weakens the credibility of the reported performance, and the authors must standardize the reference wavelength or provide a rigorous justification for using different values.\n5. There is inconsistency in the reported electrolyte thickness on page 7 of the manuscript. It was stated as 398nm earlier, but here it is 200um. The manuscript must clearly specify the actual device structure.\n6. On page 7, the authors state that the electrolyte retains good performance after repeated bending and chemical treatment. However, Figures 2e and 2f do not support this conclusion, as they only show conductivity trends without demonstrating mechanical or electrochemical stability. The conclusion is therefore not justified by the presented data.\n7. Figure 3d: the time axis is compressed and does not clearly show the claimed fast response.\n8. Figure 4c: the x-axis labeling is confusing (wavelength).\n9. Figure 5f: the photographs show external clips, casting doubt on whether the system is truly self-powered.\n10. The cost analysis (Table S3) lacks reference sources. Without citation of industrial-scale prices, this analysis appears speculative.\n11. In the section on the miniaturized spectrometer, the manuscript would benefit from a clear schematic illustrating the structural relationship between the electrochromic material and the Fabry–Pérot cavities.\n12. In Figure 8a, the FP-based spectrometer is angle-sensitive, and its resonance strongly depends on the parallelism of incident light. The use of a diffuser seems contradictory to the FP cavity principle, and the authors should justify why it was introduced and how it avoids degrading spectral accuracy.", "reviewer_2": "The manuscript entitled “All-Solid-State Electrochromic Device Enabled by p-n Complementary Conductive Polymers: From Self-Powered Smart Window to Miniaturized Spectrometer” presents an all-solid-state PEDOT:PSS/PBFDO-based OECD, which realizes two structurally unified yet functionally distinct systems: large-area self-powered smart windows and miniaturized, high-resolution spectrometers. The text provide a detailed analysis of the device design and experimental performance, showcasing a degree of innovation. However, the authors should revised this manuscript according to the questions as follows:\n1．Lines 113-116: “Cross-sectional scanning electron microscopy (SEM) analysis revealed well-defined layer thicknesses of 132 nm (PEDOT:PSS), 398 nm (electrolyte), and 116 nm (PBFDO), with field emission SEM (FESEM) images confirming the formation of dense, homogeneous, and amorphous electrochromic layers (Supplementary Fig. 1).” However, supplementary Figure 1 shows only planar SEM images, not cross-sectional SEM images. Please clarify this discrepancy or provide corresponding cross-sectional images.\n2．Lines 132-134: “As shown in Fig. 2d and Supplementary Fig. 6, increasing the film thickness from 40 nm to 350 nm led to a monotonic decrease in visible-NIR transmittance, while the conductivity saturated at 122 nm.” While the text states that PBFDO conductivity saturates at 122 nm, Fig. 2d shows continued conductivity increase up to 350 nm. Please reconcile this inconsistency with additional data or revised interpretation.\n3．Lines 140-143: “A cured thickness of 200 μm and a UV exposure time of 7 s resulted in a robust, flexible ion-conducting layer that maintained mechanical integrity during repeated bending and switching cycles (Fig. 2e, f).” The claimed mechanical stability under bending/switching cycles (stated for 200 μm-thick electrolyte with 7 s UV curing) is not directly evidenced by Fig. 2e-f. Please provide supporting data (e.g., bending tests or cycling stability plots).\n4．Figure 3d, Figure S8d and S9d: For response time calculations, please include in-situ spectra to validate the switching kinetics.\n5．The full-cell OECD exhibits significantly enhanced optical modulation and cycling stability compared to the half-cell configurations (PE-OECD and PB-OECD). While charge balance is cited as the primary factor (Lines 170-174), could other mechanisms—such as interfacial stability, ion transport kinetics, or electrochemical compatibility—also contribute to this improvement? Furthermore, would alternative counter electrode materials (e.g., inorganic oxides or other conductive polymers) yield similar performance enhancements? A more detailed discussion of these aspects would strengthen the mechanistic analysis.\n6．Figure 4a, b: Please add scale bars to Figure 4a-b for clarity.\n7．A discrepancy exists between the solar irradiance spectra (Figure 4d) and transmittance spectrum of the OECD (Figure 3a). While the faded and colored state transmittance curves intersect in the transmittance spectrum, no such intersection is observed in the solar irradiance spectra. The author is requested to provide an explanation for this phenomenon.\n8．A real-time electrochromic video demonstrating the operation of OECD and ST-OSC smart windows is necessary.\n9．The study presents three device types: OECD, ST-OSC powered large-area smart windows and on-chip organic electrochromic spectrometers. Please explicitly compare their design principles (e.g., shared materials vs. unique architectures) and justify the multi-device approach—does it demonstrate scalability, functional versatility, or technology transfer potential?\n10．There are some latest works focus on electrochromic Smart Window such as J. Phys. Chem. Lett. 2025, 16, 6585; Prog. Mater. Sci. 2025, 153, 101461; and Adv. Mater. 2025, 37, 2502706; which are highly related to the present work, recommended to the authors for discussion.", "reviewer_3": "This manuscript reports an interesting study on the integration of complementary conductive polymers into all-solid-state electrochromic devices. The authors demonstrate both large-area smart window applications and a miniaturized spectrometer platform, achieving notable performance in terms of optical contrast, switching speed, cycling stability, and spectral resolution. Overall, the topic is timely and relevant, and the work is likely to draw attention from researchers in materials science and optoelectronics. The manuscript is generally well presented, although certain aspects would benefit from further clarification and discussion. Addressing these points would enhance both the clarity and impact of the paper. I therefore recommend that the manuscript be considered for publication in Nature Communications after the authors have addressed the following questions:\n1. Regarding the smart window, is the ECD performance sensitive to the counter electrode layer? To what extent can performance be improved by employing thinner counter electrodes?\n2. The authors describe the coloring mechanism as a doping/dedoping process involving both ion insertion/extraction and electron transfer. However, why does the material additionally require Li⁺ and TFSI⁺ ions? Does their incorporation affect material transparency? Please describe in detail the changes in material during coloration and bleaching.\n3. The half-cell tests suggest that PEDOT and PBFDO exhibit similar electrochromic properties, please clarify the underlying reasons for this similarity. Furthermore, the use of ITO as the counter electrode appears to lead to poor cycling stability, attributed to charge imbalance. How is charge actually compensated on the ITO side, and in what way does this mechanism accelerate material degradation?\n4. While the manuscript demonstrates material identification by using the OECS, the potential for hyperspectral imaging applications is only briefly mentioned. how the system be extended for such applications, what are the key challenges in adapting the OECS for hyperspectral imaging in complex or dynamic environments? Further discussion on the scalability and flexibility of the system for broader imaging tasks would enhance the manuscript’s practical relevance.\n5. In Figure 7g, the MSE of spectral reconstruction decreases significantly when four voltage steps are introduced. Could the authors elaborate on the underlying reasons for this improvement? Is there a specific mechanism in the system’s operation that enhances accuracy with additional voltage steps? More detailed analysis or supporting simulations would help clarify this observation.\n6. The manuscript mentions the FP cavity design but provides limited simulation data on the light field intensity distribution across different spacer thicknesses. Please provide additional simulation data to validate the microcavity effects at varying thicknesses? Furthermore, how does the correlation coefficient distribution for each OPD pixel evolve under FP modulation?", "reviewer_4": "This manuscript focuses on the integration and hybridization of electrochromic devices with disparate technologies, notably combining Electrochromic Device Enabled by p-n complementary conductive polymers with solar cells and spectroscopic instrumentation. The work demonstrates exemplary device integration and architectural design proficiency . However, it lacks clear novelty in terms of new material design or mechanistic exploration. Consequently, I deem this manuscript not ideally suited for publication in Nature Communications. Hereby, I outline several concerns and recommendations:\n1.The term \"All-Solid-State\" in the manuscript title is technically inconsistent with the electrolyte composition. According to established classification standards for solid-state electrochromic devices, systems containing 46.3 wt% propylene carbonate (PC) solvent exceed the threshold for \"All-Solid-State\" designation (typically defined as 0 wt% solvent content). We recommend revising the title to reflect the actual material system .\n2. The x-axis label in Figure 4c contains inaccuracies. Please rigorously verify and correct all axis designations to ensure alignment with the plotted data parameters.\n3. The switching times (τc/τb) calculated from chronoamperometry (CA) curves in Figure 3d and Supplementary Information contradict standardized evaluation protocols. Electrochromic switching time must be derived from in-situ transmittance spectroscopy.\n4. The Coloration Efficiency in Figure 3e and Supplementary Information require corresponding in-situ transmittance spectroscopy. Authors should provide complete spectral datasets (ΔT% vs Time) at relevant wavelengths to substantiate the reported efficiency calculations.\n5.Counter Electrode Design Flaw: The device architecture employing ITO as a counter electrode in Supplementary Figs. 8–9 exhibits fundamental design limitations. ITO's narrow electrochemical stability window and propensity for ion accumulation compromise device cyclability—a critical oversight given the emphasis on integrated systems.\n6. The gradual self-bleaching without applied bias—termed as \"memory effect\" in the manuscript—reflects poor bistability. This behavior signifies insufficient charge trapping/retention, diminishing viability for low-energy-display applications. The authors should rephrase to accurately describe this performance limitation and address the underlying reasons.\n7. While the ECD-solar cell integration in Figure 5f improves energy efficiency, the compromised optical performance (reduced maximum transmittance and neutral colors) negates practical utility. Clarify whether this trade-off justifies integration versus standalone implementations.\n8. While this manuscript demonstrates technical proficiency in hybridizing multiple functional systems, it exhibits critical deficiencies in two fundamental dimensions: (i) Absence of novel material design and mechanistic investigation, (ii) Unsubstantiated logical coherence between disparate application extensions—exemplified by the integration of self-powered smart windows and organic electrochromic spectrometers.\nOverall, this work currently falls outside the scope of Nature Communications due to lacks significant novelty in terms of novel material design or mechanistic exploration."}, "author_response": "Point-by-point response letter accompanying our Re-Submission of:\nAll-Solid-State Electrochromic Device Enabled by p-n\nComplementary Conductive Polymers: From Self-Powered\nSmart Window to Miniaturized Spectrometer\nManuscript ID: NCOMMS-25-59872\nDear Reviewers,\nWe thank you for the conscientious peer review of our manuscript and the very helpful\ncriticism. In response to your comments, we have incorporated the suggested changes.\nIn the document below, we comment on all the concerns and points raised by the\nreviewers. For easy readability we visually structured our response as follows:\nThe comments and points of the referees are copied in black color.\nOur response is colored blue.\nFurthermore, we cite parts from the revised manuscript or the revised Supplementary\nData to afford a quick impression of the improvements and changes made to the text.\nThese citations are indicated by orange text.\nWe hope that we fully answered all the mentioned concerns and issues.\nSincerely,\nFei Huang\nReviewer #1:\nThe manuscript reports an all-solid-state complementary electrochromic device (OECD)\nbased on PEDOT:PSS and PBFDO polymers, demonstrating self-powered smart\nwindows and a miniaturized electrochromic spectrometer. The topic combines\nelectrochromic functionality with organic photodetectors to achieve multifunctional\nadaptive optoelectronic systems. However, the manuscript currently suffers from\nlogical inconsistencies and a lack of scientific rigor, with insufficient experimental\njustification. I therefore recommend rejection. Several critical aspects require\nclarification and additional evidence before the paper can be considered for publication\nelsewhere.\n1. Question or issue: The manuscript presents two applications of electrochromic\nmaterials—a self-powered smart window and a miniaturized spectrometer—but the\nlogical connection between them is weak. As written, the two parts appear as\nindependent studies rather than a coherent, unified work.\nResponse: We sincerely thank the reviewer for the valuable and insightful comment\nregarding the logical connection between the self-powered smart window and the\nminiaturized spectrometer applications. We agree that the manuscript would benefit\nfrom a clearer articulation of the unifying concept underlying these two systems. Both\napplications are built upon the same fundamental property of organic electrochromic\ndevices (OECDs), their capability to modulate optical properties in a controllable,\nvoltage-dependent manner. By highlighting this shared technological foundation, we\nemphasize that the smart window and the miniaturized spectrometer represent\ncomplementary demonstrations of the versatility and scalability of electrochromic\nmaterials across different application domains. To address the reviewer’s concern, we\nhave carefully revised the manuscript to strengthen the logical linkage between the two\napplications:\n1. Introduction: We have clarified on Page 4 that the manuscript presents two distinct\nbut technologically linked applications of OECDs: a self-powered smart window and a\nminiaturized spectrometer, both of which utilize voltage-controlled modulation of\noptical properties.\nRevision 1: This work presents two applications of OECDs, a self-powered smart\nwindow and a miniaturized spectrometer, both based on voltage-controlled modulation\nof optical properties. The smart window enables adaptive light regulation for energy-\nefficient buildings, while the spectrometer achieves precise light filtering and spectral\ndetection in a compact, portable format. Together, these results demonstrate a scalable\nelectrochromic platform that bridges large-area energy management with high-\nresolution optical sensing, positioning OECDs as a foundational technology for next-\ngeneration adaptive optoelectronics and real-time environmental monitoring.\n2. End of Smart Window Section: In the manuscript Page 16, we added discussion on\nhow the large-area, energy-efficient performance of the smart window illustrates the\npotential of electrochromic devices for integration into real-world environments\nrequiring sustainability and adaptive light regulation.\nRevision 2: By integrating the OECD with a high-efficiency ST-OSC, the system\nautonomously controls optical transmission while lowering indoor temperature,\nunderscoring its potential for large-scale, sustainable deployment.\n3. Miniaturized Spectrometer Section: In the manuscript Page 17, we clarified the\ncontrast by highlighting that, while the smart window addresses large-scale energy\nmanagement, the miniaturized spectrometer applies the same materials to compact,\nprecise spectral sensing, demonstrating adaptability at a different scale.\nRevision 3: In contrast to the large-area application of electrochromic devices in smart\nwindows, the miniaturized spectrometer targets compact, low-cost, high-resolution\nspectral sensing. Instead of regulating heat and light across a large surface, the same\nvoltage-dependent optical modulation is used to selectively filter and detect spectral\ninformation with high precision in a portable device. Building on the scalability, tunable\noptics, and self-powered operation demonstrated in OECD-based smart windows, we\ntranslate the platform into chip-scale, voltage-programmable spectrometers. By\nmonolithically integrating electrochromic filters with high-sensitivity OPDs, these\ndevices provide reconfigurable spectral filtering and computational reconstruction.\nThis transition from meter-scale dynamic windows to millimeter-scale photonic sensors\nunderscores the versatility and cross-scale adaptability of the PEDOT:PSS–PBFDO\nelectrochromic platform.\n4. Conclusion Section: We further emphasize that, although these applications target\ndifferent functions, they are inherently connected. The progress achieved in large-scale\nsmart window integration informs the development of smaller, high-resolution optical\ndevices, and vice versa, reinforcing the broad applicability of electrochromic materials\nin multifunctional optoelectronic systems (Page 26).\nRevision 4: All three devices, the standalone OECD, the ST-OSC-powered smart\nwindow, and the on-chip OECS, share the same electrochromic material system but are\ntailored for distinct functions. The OECD benchmarks device performance, the ST-OSC\nsmart window demonstrates scalable, self-powered light and heat regulation, and the\non-chip OECS enables precise spectral sensing. Together, they showcase the platform’s\nscalability, functional versatility, and potential for technology transfer from\nfundamental materials to integrated systems.\n2. Question or issue: In Figure 3g, the manuscript claims superior performance over\nboth organic and inorganic electrochromic devices, attributing this to the symmetric\nredox interplay between PEDOT and PBFDO. However, this explanation is insufficient,\nlacking specific theoretical support or experimental validation, and therefore cannot be\nconsidered convincing. Since many traditional inorganic electrochromic systems also\noperate through symmetric redox reactions, the authors should provide a more detailed\nexplanation—beyond simple charge balance—to clarify why their device outperforms\nestablished inorganic counterparts in both speed and efficiency\nResponse: Thank you so much for your thoughtful and constructive comment. We\ngreatly appreciate your valuable feedback and agree that a more detailed explanation is\nnecessary to clarify the outstanding performance of our device. Here, we have explored\nthe critical factors in achieving the high speed and efficiency observed in our device.\nThese include:\n1. Energetic Offsets and Ionic Diffusion: The polymers exhibit symmetric redox\npotentials and well-matched ionic diffusion coefficients, which enable the rapid and\nsynchronized optical switching.\n2. Charge Capacitance: Both polymers show comparable high charge capacitance,\nwhich not only promotes redox kinetics that yields large optical modulation and high\ncoloration efficiency, but also ensures efficient charge balance, minimizes parasitic\nreactions, reduces power consumption, and contributes to the long-term cycling\nstability of the device.\nWe have added additional experimental data to the manuscript in Page 10, including\nredox potentials, ionic diffusion coefficients and capacitance calculations. These data\nstrongly support the device's superior performance from the intrinsic properties of EC\nmaterials.\nRevision: Given the exceptional electrochromic performance of complementary ECDs,\nwe investigated the intrinsic properties of EC materials. Both polymers exhibit\nfavorable energetic offsets (symmetric open-circuit and redox potentials) and matched\nionic diffusion coefficients, enabling rapid and synchronized optical switching\n(Supplementary Fig. 17 and Supplementary Fig. 18). Additionally, their high and\ncomparable charge capacitance not only promotes redox kinetics that yields large\noptical modulation and high coloration efficiency, but also ensures efficient charge\nbalance, reduces power consumption, and enhances cycling stability (Supplementary\nFig. 19).\nSupplementary Fig. 17. CV of PEDOT:PSS (a) and PBFDO (b) in 2.2 wt % LiTFSI\n(0.085 mol L-1) in PC. Reduction potential of PEDOT:PSS, oxidation potential of\nPBFDO and their open circuit potentials (P ) are indicated in the figure.\nOC\nSupplementary Fig. 18. Ionic diffusion coefficient of PEDOT:PSS and PBFDO\nfilms. (a) CV of PEDOT:PSS at different scan rates. (b) Reduction peak current plotted\nvs scan rate1/2 from (a). (c) CV of PBFDO at different scan rates. (d) Oxidation peak\ncurrent plotted vs scan rate1/2 from (c). Note: The scan rates, from lowest to highest,\nare 0.1 V s-1, 0.2 V s-1, 0.3 V s-1, and 0.4 V s-1, respectively.\nThe ionic diffusion coefficient (𝐷) of EC films can be calculated using the Randles–\nŠevčík equation:\n𝑖 = (2.687×105)𝑛3⁄2𝐴𝐷1⁄2𝐶𝑣1⁄2\n𝑝\nwhere 𝑖 is the reduction or oxidation peak current (amperes), 𝑛 is the number of\n𝑝\nelectrons transferred in a redox cycle, 𝐴 is the electrode surface area in working (cm2),\n𝐶 is the molar concentration of redox-active species (mol cm−3), 𝐷 is the diffusion\ncoefficient (cm2 s−1), and 𝑣 is the scan rate in V s−1.\nWe tested the CV curves of EC films in 2.2 wt % LiTFSI (0.085 mol L-1) in PC at\nvarious scan rates to determine the peak currents of PEDOT:PSS during reduction and\nPBFDO during oxidation. Subsequently, we plotted the peak currents against the square\nroot of the scan rate (𝑣1⁄2 ) to derive the corresponding slopes (k), which can be\nexpressed as:\n𝑘 = (2.687×105)𝑛3⁄2𝐴𝐷1⁄2𝐶\nSubstituting the measured values into the equation, we calculate 𝐷. For PEDOT:PSS,\nwith k is -0.0035 mol s-1/2, and for PBFDO, with k is -0.00346 mol s-1/2, we\nPEDOT PBFDO\nobtain:\nFor PEDOT:PSS:\n𝑘 2 1 0.0035 2\n𝐷 = ( ) = ( ) = 1.04×10−8 cm2 s−1\n2.687×105 𝑛3𝐴2𝐶2 34.25925\nFor PBFDO:\n𝑘 2 1 0.00346 2\n𝐷 = ( ) = ( ) = 1.01×10−8 cm2 s−1\n2.687×105 𝑛3𝐴2𝐶2 34.25925\nBoth polymers exhibit favorable energetic offsets (symmetric open-circuit and redox\npotentials) (Supplementary Fig. 17), and high and perfectly aligned ionic diffusion\ncoefficients, which ensure the efficiency of the redox process, contributing to the fast\nswitching speed of the complementary ECDs.\nSupplementary Fig. 19. Capacitance of PEDOT:PSS and PBFDO films. (a) CV of\nPEDOT:PSS at different scan rates. (b) Averaged anodic and cathodic current at 0 V (vs.\nAg/AgCl) plotted vs scan rate from (a). (c) CV of PBFDO at different scan rates. (d)\nAveraged anodic and cathodic current at 0.3 V (vs. Ag/AgCl) plotted vs scan rate from\n(c). Note: The scan rates, from lowest to highest, are 5 mV s-1, 10 mV s-1, 20 mV s-1,\n30 mV s-1, 40 mV s-1, 50 mV s-1, 60 mV s-1, 70 mV s-1, 80 mV s-1, 90 mV s-1, and 100\nmV s-1.\nThe specific volumetric capacitance (𝐶∗ ) of EC films was determined by recording\ncyclic voltammograms at different scan rates in 2.2 wt % LiTFSI (0.085 mol L-1) in PC.\nAs shown in Supplementary Fig. 18 (a) and (c), the non-Faradaic regions between -0.2\nV to +0.2 V and +0.2 V to +0.4 V correspond to the double-layer capacitance of\nPEDOT:PSS and PBFDO films, respectively. The capacitive behavior is confirmed by\nthe linear increase in current density with the scan rate, as described by the following\nequation:\n(𝐼 −𝐼 )⁄2 = 𝐶𝑣\n𝑎 𝑐\n𝐼 and 𝐼 represent the anodic and cathodic current densities measured at 0 V (for\na c\nPEDOT:PSS) and 0.3 V (for PBFDO), respectively, within the voltage range exhibiting\ncapacitive behavior. 𝜈 is the scan rate and 𝐶 is the volumetric capacitance. The\nspecific volumetric capacitance (𝐶∗) is calculated by dividing 𝐶 by the film thickness\n(𝑡).\nFrom the slope, the capacitances are 𝐶 = 1.78×10−3 F cm−2 and 𝐶 =\nPEDOT PBFDO\n1.96×10−3 F cm−2.\nFor PEDOT:PSS:\n𝐶 1.78×10−3 F cm−2\n𝐶∗ = PEDOT = = 207 F cm−3\nPEDOT 𝑡 86 nm\nPEDOT\nFor PBFDO:\n𝐶 1.96×10−3 F cm−2\n𝐶∗ == PBFDO = = 210 F cm−3\nPBFDO 𝑡 92 nm\nPBFDO\nIn summary, two polymers exhibit high and comparable charge capacitance: (1) High\nspecific volumetric capacitance (𝐶∗ ) allows more charge injection even at low film\nthicknesses, promoting faster redox kinetics that yield large optical modulation, high\ncoloration efficiency and more pronounced color transitions. (2) Comparable charge\ncapacitance between the two polymers ensures efficient charge balance and minimizes\nparasitic side reactions, significantly reducing the power consumption and improving\ncycling stability of the device.\n3. Question or issue: The claim of “excellent cycling stability” is questionable. Many\nelectrochromic systems demonstrate stability beyond 20,000 cycles. Moreover,\nperformance metrics are compared across inconsistent voltage ranges (e.g., Figure 3g\noptical contrast at ±2 V, stability at ±1 V). Fair benchmarking requires unified operating\nconditions.\nResponse: Thank you for your valuable comment. As detailed in Supplementary Table\n2, our OECD demonstrates competitive performance, ranking at the middle-to-upper\nlevel when compared to recent electrochromic devices. Additionally, we have\nstandardized the performance metrics across all measurements using a consistent\nvoltage range of ±2 V. The radar plot in Figure 3g has been updated accordingly to\nreflect these standardized conditions.\nRevision :\nFig. 3g. Radar plot comparing key performance metrics against representative state-of-\nthe-art ECDs.\n4. Question or issue: The manuscript reports transmittance at multiple, inconsistent\nwavelengths (506 nm, 550 nm, 574 nm, 694 nm), which undermines the scientific rigor\nof the comparisons. Such inconsistency weakens the credibility of the reported\nperformance, and the authors must standardize the reference wavelength or provide a\nrigorous justification for using different values.\nResponse: Thank you very much for your thoughtful and constructive comment. As\nshown in Figure 1c, the transmittance spectra of PEDOT and PBFDO reveal minimal\nabsorption at 506 nm and 574 nm, respectively, which are close to 550 nm—the peak\nsensitivity wavelength of the human eye. Their high transmittance in the bleached state\nhighlights their potential as promising electrochromic materials for architectural\napplications. Furthermore, wavelengths such as 612 nm (Supplementary Fig. 8a), 694\nnm (Supplementary Fig. 9a), 594 nm (Supplementary Fig. 11a), 586 nm\n(Supplementary Fig. 12a), and 570 nm (Fig. 3a) correspond to the wavelengths at which\nmaximum optical modulation occurs for various electrochromic devices, including PE-\nOECD, PB-OECD, PE-OECD with an ultra-thin PBFDO film as the counter electrode,\nPB-OECD with an ultra-thin PEDOT:PSS film as the counter electrode, and\ncomplementary OECD. Since different electrochromic devices exhibit maximum\ncontrast at different wavelengths, we focus on the contrast ratio at these specific\nwavelengths when comparing performance. We hope this clarifies the rationale behind\nour choice of wavelengths.\n5. Question or issue: There is inconsistency in the reported electrolyte thickness on\npage 7 of the manuscript. It was stated as 398 nm earlier, but here it is 200 um. The\nmanuscript must clearly specify the actual device structure.\nResponse: Thank you for your valuable comment. For the fabrication of the OECD, we\nused 3M polyimide tapes with a total thickness of 200 μm around the ITO/PBFDO glass,\nresulting in an electrolyte layer of 200 μm thickness. However, for the cross-sectional\nSEM analysis, the liquid electrolyte was placed into a cavity formed by the 200 μm\npolyimide tapes around one ITO glass and covered with another ITO glass. After UV\ncuring, one ITO glass was removed, and the remaining ITO with the electrolyte film\nwas used for SEM imaging. Unfortunately, the electrolyte film shrank and detached\nupon exposure to air, leading to significant distortion in the measured thickness. To\naddress this, we have updated Figure 2a and clarified the explanation on Page 6, while\ndiscarding the distorted images from the manuscript.\nRevision: Cross-sectional scanning electron microscopy (SEM) analysis (Fig. 2a)\nrevealed well-defined layer thicknesses of 132 nm for PEDOT:PSS and 116 nm for\nPBFDO.\nFig. 2a. Schematic illustration and cross-sectional SEM image of the multilayer OECD\nstructure.\n6. Question or issue: On page 7, the authors state that the electrolyte retains good\nperformance after repeated bending and chemical treatment. However, Figures 2e and\n2f do not support this conclusion, as they only show conductivity trends without\ndemonstrating mechanical or electrochemical stability. The conclusion is therefore not\njustified by the presented data.\nResponse: Thank you for your valuable comment. Regarding the optimization of\nelectrolyte layer, we have systematically investigated the effects of\nphotopolymerization time and film thickness on both the conductivity and morphology\nof the electrolyte film. Insufficient curing leads to incomplete crosslinking, resulting in\nresidual monomers, surface tackiness, and compromised ionic transport. On the other\nhand, excessive curing causes high crosslinking density, leading to film shrinkage,\nembrittlement, and microcracking, which negatively affect both film flexibility and\nconductivity. And in response to your concern, we fabricated a flexible EC device to\nassess the mechanical stability of the electrolyte film, as shown in Figure 2g.\nAdditionally, we have included the following sentences in the main text on Page 7 to\nbetter explain these findings.\nRevision: The solid-state electrolyte was optimized for both ionic transport and film\nmorphology. A cured thickness of 200 μm and a UV exposure time of 7 s resulted in\nhigh conductivity (Fig. 2e, f) and a robust, flexible ion-transport layer (Fig. 2g). The\n10 × 10 cm² flexible OECD showed only a 7% optical contrast loss after 5,000 bending\ncycles.\nFig. 2g. Mechanical stability test of the electrolyte layer using a flexible OECD with a\ncurvature radius of 1 cm.\n7. Question or issue: Figure 3d: the time axis is compressed and does not clearly show\nthe claimed fast response.\nResponse: We sincerely appreciate the reviewer for pointing out this issue. To better\nillustrate the device’s response speed, we have replaced the original CA curves with in\nsitu transmittance-time curves in Figure 3d. The following revised text has been\nupdated on Page 9.\nRevision: Notably, the OECD demonstrates exceptional electrochromic dynamics, with\nswitching times of 0.17 s for coloration and 0.36 s for bleaching (Fig. 3d).\nFig. 3d. Transmission spectrum at 550 nm for the OECD in its colored and bleached\nstates, at applied voltages of -2 V and 2 V, respectively.\n8. Question or issue: Figure 4c: the x-axis labeling is confusing (wavelength).\nResponse: Thank you for your valuable comment. The necessary corrections have been\nmade to the x-axis labeling in Figure 4c to ensure clarity.\nRevision:\n.\nFig. 4c. Dynamic transmittance at 550 nm measured at the center and edge of the device\nduring a full switching cycle (from -2 V to 2 V).\n9. Question or issue: Figure 5f: the photographs show external clips, casting doubt on\nwhether the system is truly self-powered.\nResponse: We sincerely thank the reviewer for raising this critical point. As a\nsupplement, we have demonstrated two videos of the ST-OSC–OECD module in\ncoloration (Supplementary Video 1) and bleaching (Supplementary Video 2),\nrespectively. We have also revised the manuscript in Page 15 accordingly.\nRevision : The integrated system transitions from a light-blue transparent state to a\ndark-blue colored state under illumination (Supplementary Fig. 24 and Supplemental\nVideo 1 and 2), demonstrating functional synergy.\n10. Question or issue: The cost analysis (Table S3) lacks reference sources. Without\ncitation of industrial-scale prices, this analysis appears speculative.\nResponse: We sincerely appreciate the reviewer for pointing out this important issue.\nThe industrial-scale prices of the raw materials used in this work were obtained through\ndirect consultation with suppliers and referencing relevant literature. Specifically:\n1. We contacted Foshan Jingjiexin Glass Co., Ltd for the industrial price of ITO.\n2. We consulted Jurong Optoelectronic Materials Technology Co., Ltd for the price of\nPBFDO.\n3. For PEDOT:PSS, we contacted Heraeus Co., Ltd and referenced literature (Adv.\nFunct. Mater. 2024, 34, 2312358).\n4. We also contacted Energy Chemical Co., Ltd and referred to literature (Adv. Funct.\nMater. 2024, 34, 2312358) for the price of LiTFSI.\n5. The industrial price of PEGDA was obtained from Aladdin Co., Ltd.\n6. We consulted Energy Chemical Co., Ltd for the price of 1173 photoinitiator and PC.\nIn addition, we verified these prices using industry data platforms such as ICIS, Argus\nMedia, and ChemAnalyst, all of which confirmed that the prices fall within the quoted\nrange. To enhance transparency, we have updated Supplementary Table 3 to include\nthese references.\nRevision:\nSupplementary Table 3. Price estimation of PEDOT-PBFDO electrochromic smart\nwindows.\nAreal Mass Price (Industrial\nRaw Material Price Source\nLoading Scale)\nPEDOT:PSS 50 ml m−2 ~0.15 USD ml−1 Heraeus Co., Ltd.\nJurong Optoelectronic Materials\nPBFDO 50 ml m−2 ~0.15 USD ml−1\nTechnology Co., Ltd\nITO glass N.A. ~27 USD m−2 Jingjiexin Glass Co., Ltd\nPC 107.76 g m−2 ~0.003 USD g−1 Energy Chemical Co., Ltd.\nLiTFSI 5.12 g m−2 ~0.21 USD g−1 Energy Chemical Co., Ltd.\n1173\n19.32 g m−2 ~0.019 USD g−1 Energy Chemical Co., Ltd.\nphotoinitiator\nPEGDA 100.54 g m−2 ~0.075 USD g−1 Aladdin Co., Ltd.\n11. Question or issue: In the section on the miniaturized spectrometer, the manuscript\nwould benefit from a clear schematic illustrating the structural relationship between the\nelectrochromic material and the Fabry–Pérot cavities.\nResponse: In response, we have added a schematic diagram (Supplementary Fig. 29)\nto clarify the structural relationship. The OECD and the FP cavities are fabricated on\ntwo substrates and enclosed within a sealed casing. From the perspective of incident\nlight, the beam sequentially passes through the electrochromic layer, the FP cavities of\nvarying thickness, and finally reaches the OPD array. We have also revised the\nmanuscript in Page 19 accordingly.\nRevision: The structural relationship between the OECD and the FP cavities is\nillustrated in Supplementary Fig. 29.\nSupplementary Fig. 29. Cross-sectional schematic showing the structural\nconfiguration of the OECD and the FP cavities.\n12. Question or issue: In Figure 8a, the FP-based spectrometer is angle-sensitive, and\nits resonance strongly depends on the parallelism of incident light. The use of a diffuser\nseems contradictory to the FP cavity principle, and the authors should justify why it\nwas introduced and how it avoids degrading spectral accuracy.\nResponse: We sincerely thank the reviewer for this insightful comment. Indeed, even\nwhen using an oversized light spot to ensure spatial uniformity, slight angular\ndivergences in real-world illumination can cause variations in the incident angle across\nthe FP array, leading to pixel-to-pixel shifts in the resonant wavelength. To address this,\nwe introduced a narrow-angle engineered diffuser, which serves as an angular\nhomogenizer. It ensures that the average incident angle on each FP cavity remains near-\nnormal, providing a consistent angular benchmark across the array. This approach\nprevents systematic spectral shifts and is essential for accurate spectral reconstruction,\nwhile preserving the intrinsic spectral resolution of the FP cavities, as confirmed by our\nmeasurements. We revised the following content of the manuscript in Page 23:\nRevision: A narrow-angle engineered diffuser was incorporated to homogenize the\nangular distribution of the incident light followed sequentially by the OECS. By\nmaintaining near-normal incidence across all FP cavities, the diffuser ensures a\nconsistent spectral baseline without significantly broadening the FP resonance peaks,\nthus preserving the intrinsic spectral resolution critical for accurate reconstruction.\nReviewer #2:\nThe manuscript entitled “All-Solid-State Electrochromic Device Enabled by p-n\nComplementary Conductive Polymers: From Self-Powered Smart Window to\nMiniaturized Spectrometer” presents an all-solid-state PEDOT:PSS/PBFDO-based\nOECD, which realizes two structurally unified yet functionally distinct systems: large-\narea self-powered smart windows and miniaturized, high-resolution spectrometers. The\ntext provide a detailed analysis of the device design and experimental performance,\nshowcasing a degree of innovation. However, the authors should revised this\nmanuscript according to the questions as follows:\n1. Question or issue: Lines 113-116: “Cross-sectional scanning electron microscopy\n(SEM) analysis revealed well-defined layer thicknesses of 132 nm (PEDOT:PSS),\n398 nm (electrolyte), and 116 nm (PBFDO), with field emission SEM (FESEM) images\nconfirming the formation of dense, homogeneous, and amorphous electrochromic\nlayers (Supplementary Fig. 1).” However, supplementary Figure 1 shows only planar\nSEM images, not cross-sectional SEM images. Please clarify this discrepancy or\nprovide corresponding cross-sectional images.\nResponse: We apologize for the confusion caused by the discrepancy. Figure 2a shows\nthe cross-sectional SEM images, while Supplementary Fig. 1 presents the surface\nFESEM images. Unfortunately, this was not clearly stated in the main text, leading to\nthe misunderstanding. We have now provided a clearer explanation on Page 6 to address\nthis issue.\nRevision: Cross-sectional scanning electron microscopy (SEM) analysis (Fig. 2a)\nrevealed well-defined layer thicknesses of 132 nm for PEDOT:PSS, and 116 nm for\nPBFDO, with field emission SEM (FESEM) images confirming the formation of dense,\nhomogeneous, and amorphous electrochromic layers (Supplementary Fig. 1).\n2. Question or issue: Lines 132-134: “As shown in Fig. 2d and Supplementary Fig. 6,\nincreasing the film thickness from 40 nm to 350 nm led to a monotonic decrease in\nvisible-NIR transmittance, while the conductivity saturated at 122 nm.” While the text\nstates that PBFDO conductivity saturates at 122 nm, Fig. 2d shows continued\nconductivity increase up to 350 nm. Please reconcile this inconsistency with additional\ndata or revised interpretation.\nResponse: We sincerely thank the reviewer for this insightful comment. As pointed out,\nthe transmittance and conductivity of PBFDO films generally exhibit inverse trends\nwith increasing thickness (Fig. 2d and Supplementary Fig. 6). Specifically, for\nconductivity, when the film thickness increased from 37 nm to 80 nm, the conductivity\nincreased significantly from 1116 S cm⁻¹ to 1350 S cm⁻¹, a change of 234 S cm⁻¹.\nHowever, from 80 nm to 122 nm, the conductivity plateaued, rising only slightly from\nthickness from 122 nm to 346 nm resulted in a smaller conductivity increase from 1353\nS cm⁻¹ to 1435 S cm⁻¹ (an 82 S cm⁻¹ increase), while the transmittance decreased\nsignificantly from 60% to 27%. This drop in transmittance substantially reduced the\ndevice's performance in the bleached state. To summarize, we focused on PBFDO films\nwith thicknesses in the 80-122 nm range for device fabrication, as this thickness range\nprovides an optimal balance between conductivity and transmittance.\n3. Question or issue: Lines 140-143: “A cured thickness of 200 μm and a UV exposure\ntime of 7 s resulted in a robust, flexible ion-conducting layer that maintained\nmechanical integrity during repeated bending and switching cycles (Fig. 2e, f).” The\nclaimed mechanical stability under bending/switching cycles (stated for 200 μm-thick\nelectrolyte with 7 s UV curing) is not directly evidenced by Fig. 2e-f. Please provide\nsupporting data (e.g., bending tests or cycling stability plots).\nResponse: Thank you for the insightful comment. We appreciate the reviewer’s\nsuggestion. To clarify, we systematically investigated how photopolymerization time\nand film thickness impact the electrolyte’s conductivity and film morphology.\nInsufficient curing results in incompletely crosslinked networks with residual\nmonomers, leading to surface tackiness and compromised ionic transport. On the other\nhand, excessive curing induces high crosslinking density, causing shrinkage,\nembrittlement, and microcracking, which impair both film flexibility and conductivity.\nTo demonstrate the mechanical stability under bending and switching cycles, we\nfabricated a flexible EC device, as shown in Fig. 2g. The device exhibited a 7% optical\ncontrast loss after 5,000 bending cycles, confirming its excellent mechanical stability.\nWe have added the following sentences in the main text on Page 7 to clarify this point.\nRevision: The solid-state electrolyte was optimized for both ionic transport and film\nmorphology. A cured thickness of 200 μm and a UV exposure time of 7 s resulted in\nhigh conductivity (Fig. 2e, f) and a robust, flexible ion-transport layer (Fig. 2g). The\n10 × 10 cm² flexible OECD showed only a 7% optical contrast loss after 5,000 bending\ncycles.\nFig. 2g. Mechanical stability test of the electrolyte layer using a flexible OECD with a\ncurvature radius of 1 cm.\n4. Question or issue: Figure 3d, Figure S8d and S9d: For response time calculations,\nplease include in-situ spectra to validate the switching kinetics.\nResponse: We sincerely thank the reviewer for raising these important points regarding\nthe calculation of switching times. In response, we have replaced all CA curves with\nin-situ transmittance-time curves to better validate the switching kinetics. The\ncorresponding modifications have been made in Figure 3d, Supplementary Fig. 8d,\nSupplementary Fig. 9d, Supplementary Fig. 11d, and Supplementary Fig. 12d.\nRevision:\n5. Question or issue: The full-cell OECD exhibits significantly enhanced optical\nmodulation and cycling stability compared to the half-cell configurations (PE-OECD\nand PB-OECD). While charge balance is cited as the primary factor (Lines 170-174),\ncould other mechanisms—such as interfacial stability, ion transport kinetics, or\nelectrochemical compatibility—also contribute to this improvement? Furthermore,\nwould alternative counter electrode materials (e.g., inorganic oxides or other conductive\npolymers) yield similar performance enhancements? A more detailed discussion of\nthese aspects would strengthen the mechanistic analysis.\nResponse: We sincerely thank the reviewer for raising these insightful points. We\nwould like to address the two aspects raised as follows:\n1. On the Mechanism Behind the Enhanced Performance: We investigated the\nunderlying factors contributing to the high performance of the full-cell OECD. The two\nconductive polymers exhibit favorable energetic offsets, including symmetric open-\ncircuit and redox potentials, as well as matched ionic diffusion coefficients and\ncomparable charge capacitance. These properties enable their effective integration into\ncomplementary OECDs, leading to synchronized and rapid optical switching, high\noptical contrast, high coloration efficiency, low energy consumption, and exceptional\nlong-term cycling stability. We have added the following explanation on Page 10:\nRevision: Given the exceptional electrochromic performance of complementary ECDs,\nwe investigated the intrinsic properties of EC materials. Both polymers exhibit\nfavorable energetic offsets (symmetric open-circuit and redox potentials) and matched\nionic diffusion coefficients, enabling rapid and synchronized optical switching\n(Supplementary Fig. 17 and Supplementary Fig. 18). Additionally, their high and\ncomparable charge capacitance not only promotes redox kinetics that yields large\noptical modulation and high coloration efficiency, but also ensures efficient charge\nbalance, reduces power consumption, and enhances cycling stability (Supplementary\nFig. 19).\nSupplementary Fig. 17. CV of PEDOT:PSS (a) and PBFDO (b) in 2.2 wt % LiTFSI\n(0.085 mol L-1) in PC. Reduction potential of PEDOT:PSS, oxidation potential of\nPBFDO and their open circuit potentials (P ) are indicated in the figure.\nOC\n.\nSupplementary Fig. 18. Ionic diffusion coefficient of PEDOT:PSS and PBFDO\nfilms. (a) CV of PEDOT:PSS at different scan rates. (b) Reduction peak current plotted\nvs scan rate1/2 from (a). (c) CV of PBFDO at different scan rates. (d) Oxidation peak\ncurrent plotted vs scan rate1/2 from (c). Note: The scan rates, from lowest to highest,\nare 0.1 V s-1, 0.2 V s-1, 0.3 V s-1, and 0.4 V s-1, respectively.\nThe ionic diffusion coefficient (𝐷) of EC films can be calculated using the Randles–\nŠevčík equation:\n𝑖 = (2.687×105)𝑛3⁄2𝐴𝐷1⁄2𝐶𝑣1⁄2\n𝑝\nwhere 𝑖 is the reduction or oxidation peak current (amperes), 𝑛 is the number of\n𝑝\nelectrons transferred in a redox cycle, 𝐴 is the electrode surface area in working (cm2),\n𝐶 is the molar concentration of redox-active species (mol cm−3), 𝐷 is the diffusion\ncoefficient (cm2 s−1), and 𝑣 is the scan rate in V s−1.\nWe tested the CV curves of EC films in 2.2 wt % LiTFSI (0.085 mol L-1) in PC at\nvarious scan rates to determine the peak currents of PEDOT:PSS during reduction and\nPBFDO during oxidation. Subsequently, we plotted the peak currents against the square\nroot of the scan rate (𝑣1⁄2 ) to derive the corresponding slopes (k), which can be\nexpressed as:\n𝑘 = (2.687×105)𝑛3⁄2𝐴𝐷1⁄2𝐶\nSubstituting the measured values into the equation, we calculate 𝐷. For PEDOT:PSS,\nwith k is -0.0035 mol s-1/2, and for PBFDO, with k is -0.00346 mol s-1/2, we\nPEDOT PBFDO\nobtain:\nFor PEDOT:PSS:\n𝑘 2 1 0.0035 2\n𝐷 = ( ) = ( ) = 1.04×10−8 cm2 s−1\n2.687×105 𝑛3𝐴2𝐶2 34.25925\nFor PBFDO:\n𝑘 2 1 0.00346 2\n𝐷 = ( ) = ( ) = 1.01×10−8 cm2 s−1\n2.687×105 𝑛3𝐴2𝐶2 34.25925\nBoth polymers exhibit favorable energetic offsets (symmetric open-circuit and redox\npotentials) (Supplementary Fig. 17), and high and perfectly aligned ionic diffusion\ncoefficients, which ensure the efficiency of the redox process, contributing to the fast\nswitching speed of the complementary ECDs.\nSupplementary Fig. 19. Capacitance of PEDOT:PSS and PBFDO films. (a) CV of\nPEDOT:PSS at different scan rates. (b) Averaged anodic and cathodic current at 0 V (vs.\nAg/AgCl) plotted vs scan rate from (a). (c) CV of PBFDO at different scan rates. (d)\nAveraged anodic and cathodic current at 0.3 V (vs. Ag/AgCl) plotted vs scan rate from\n(c). Note: The scan rates, from lowest to highest, are 5 mV s-1, 10 mV s-1, 20 mV s-1,\n30 mV s-1, 40 mV s-1, 50 mV s-1, 60 mV s-1, 70 mV s-1, 80 mV s-1, 90 mV s-1, and 100\nmV s-1.\nThe specific volumetric capacitance (𝐶∗ ) of EC films was determined by recording\ncyclic voltammograms at different scan rates in 2.2 wt % LiTFSI (0.085 mol L-1) in PC.\nAs shown in Supplementary Fig. 18 (a) and (c), the non-Faradaic regions between -0.2\nV to +0.2 V and +0.2 V to +0.4 V correspond to the double-layer capacitance of\nPEDOT:PSS and PBFDO films, respectively. The capacitive behavior is confirmed by\nthe linear increase in current density with the scan rate, as described by the following\nequation:\n(𝐼 −𝐼 )⁄2 = 𝐶𝑣\n𝑎 𝑐\n𝐼 and 𝐼 represent the anodic and cathodic current densities measured at 0 V (for\na c\nPEDOT:PSS) and 0.3 V (for PBFDO), respectively, within the voltage range exhibiting\ncapacitive behavior. 𝜈 is the scan rate and 𝐶 is the volumetric capacitance. The\nspecific volumetric capacitance (𝐶∗) is calculated by dividing 𝐶 by the film thickness\n(𝑡).\nFrom the slope, the capacitances are 𝐶 = 1.78×10−3 F cm−2 and 𝐶 =\nPEDOT PBFDO\n1.96×10−3 F cm−2.\nFor PEDOT:PSS:\n𝐶 1.78×10−3 F cm−2\n𝐶∗ = PEDOT = = 207 F cm−3\nPEDOT 𝑡 86 nm\nPEDOT\nFor PBFDO:\n𝐶 1.96×10−3 F cm−2\n𝐶∗ == PBFDO = = 210 F cm−3\nPBFDO 𝑡 92 nm\nPBFDO\nIn summary, two polymers exhibit high and comparable charge capacitance: (1) High\nspecific volumetric capacitance (𝐶∗ ) allows more charge injection even at low film\nthicknesses, promoting faster redox kinetics that yield large optical modulation, high\ncoloration efficiency and more pronounced color transitions. (2) Comparable charge\ncapacitance between the two polymers ensures efficient charge balance and minimizes\nparasitic side reactions, significantly reducing the power consumption and improving\ncycling stability of the device.\n2. On Alternative Counter Electrode Materials: We appreciate the reviewer’s inquiry\nregarding the potential use of alternative counter electrode materials. We believe that\nhigh-performance ECDs can indeed be realized using various EC materials, whether\ninorganic oxides or conductive polymers, provided they exhibit the following key\nproperties: Symmetric redox potentials and matched ionic diffusion coefficients to\nensure synchronized switching and compatible capacitance to minimize charge\nimbalance at the electrode-electrolyte interface. In future work, we will explore\ndifferent combinations of electrochromic materials to further evaluate their impact on\ndevice performance.\n6. Question or issue: Figure 4a, b: Please add scale bars to Figure 4a-b for clarity.\nResponse: We sincerely thank the reviewer for raising the insightful comment. We have\nadded scale barsto Figures 4a and 4b, respectively.\nRevision :\nFig. 4. a Photographs of a 20 × 20 cm² OECD fabricated via blade coating. b A flexible\n10 × 10 cm² device under mechanical bending.\n7. Question or issue: A discrepancy exists between the solar irradiance spectra (Figure\n4d) and transmittance spectrum of the OECD (Figure 3a). While the faded and colored\nstate transmittance curves intersect in the transmittance spectrum, no such intersection\nis observed in the solar irradiance spectra. The author is requested to provide an\nexplanation for this phenomenon.\nResponse: We sincerely thank the reviewer for raising this insightful comment. As\npointed out, the transmittance spectra of the 5 cm × 5 cm OECD in Figure 3a show an\nintersection point in the near-infrared region at both -2 V and 2 V. However, in Figure\n4d, we have converted the transmittance spectra (Supplementary Fig. 21) of the 10 cm\n× 10 cm OECD, spanning 400 to 2000 nm at different bias voltages, into solar irradiance\nspectra. In this case, the transmittance spectra at -2 V and 2 V also exhibit an\nintersection point at approximately 1120 nm. In the converted solar irradiance spectra,\nwe can clearly observe that the spectra at both voltages overlap near 1120 nm,\naddressing the discrepancy raised by the reviewer.\nFig. 4d. Solar irradiance spectra derived from the measured transmittance spectra at\ndifferent bias voltages.\n8. Question or issue: A real-time electrochromic video demonstrating the operation of\nOECD and ST-OSC smart windows is necessary.\nResponse: We sincerely thank the reviewer for raising this critical point. As a\nsupplement, we have demonstrated two videos of the ST-OSC–OECD module in\ncoloration (Supplementary Video 1) and bleaching (Supplementary Video 2),\nrespectively. We have also revised the manuscript in Page 15 accordingly.\nRevision : The integrated system transitions from a light-blue transparent state to a\ndark-blue colored state under illumination (Supplementary Fig. 24 and Supplemental\nVideo 1 and 2), demonstrating functional synergy.\n9. Question or issue: The study presents three device types: OECD, ST-OSC powered\nlarge-area smart windows and on-chip organic electrochromic spectrometers. Please\nexplicitly compare their design principles (e.g., shared materials vs. unique\narchitectures) and justify the multi-device approach—does it demonstrate scalability,\nfunctional versatility, or technology transfer potential?\nResponse: We sincerely thank the reviewer for this insightful comment, which provides\nan opportunity to clarify the unifying vision and strategic rationale of our work. All\nthree devices, the standalone OECD, the ST-OSC-powered smart window, and the on-\nchip organic electrochromic spectrometer (OECS), are built upon the same\nelectrochromic material system, yet each is tailored through distinct architectures to\nhighlight different aspects of our platform’s capability. The standalone OECD serves\nas a performance benchmark, establishing fundamental device characteristics. The ST-\nOSC smart window demonstrates scalability and energy autonomy via photovoltaic\nintegration, showcasing applicability at the building scale. The on-chip spectrometer\nrepurposes the electrochromic layer as a programmable filter, enabling precise spectral\nsensing at the microscale.\nCollectively, these devices validate the platform’s scalability from meters to millimeters,\nits functional versatility from macroscopic light modulation to microscopic spectral\nanalysis, and its potential for technology transfer from basic materials research to\nintegrated systems and advanced sensing applications. This multi-device strategy\nunderscores the broad applicability and practical relevance of our electrochromic\nplatform. Accordingly, we added the following sentences in the Conclusion section in\nPage 26:\nRevision: All three devices, the standalone OECD, the ST-OSC-powered smart window,\nand the on-chip OECS, share the same electrochromic material system but are tailored\nfor distinct functions. The OECD benchmarks device performance, the ST-OSC smart\nwindow demonstrates scalable, self-powered light and heat regulation, and the on-chip\nOECS enables precise spectral sensing. Together, they showcase the platform’s\nscalability, functional versatility, and potential for technology transfer from\nfundamental materials to integrated systems.\n10. Question or issue: There are some latest works focus on electrochromic Smart\nWindow such as J. Phys. Chem. Lett. 2025, 16, 6585-6593; Prog. Mater. Sci. 2025,\n153, 101461; and Adv. Mater. 2025, 37, 2502706; which are highly related to the present\nwork, recommended to the authors for discussion.\nResponse: We sincerely thank the reviewer for pointing out these recent and highly\nrelevant works. We have carefully reviewed the suggested references and have now\nincluded a discussion of them in the revised manuscript in the Introduction section.\nRevision:\n4. Wang, J. et al. Roadmap for electrochromic smart devices: From materials\nengineering and architectures design to multifunctional application. Prog. Mater. Sci.\n153, 101461 (2025).\n6. Zhou, Y. et al. Electrochromic Smart Windows with On-Demand Photothermal\nRegulation for Energy-Saving Buildings. Adv. Mater. 37, 2502706 (2025).\n15. Guo X. et al. Synergistic Structural-Compositional Modification of V\n5\n/C Films\nfor Enhanced Multicolor Electrochromic Devices. J. Phys. Chem. Lett. 16, 6585-6593\n(2025).\nReviewer #3:\nThis manuscript reports an interesting study on the integration of complementary\nconductive polymers into all-solid-state electrochromic devices. The authors\ndemonstrate both large-area smart window applications and a miniaturized\nspectrometer platform, achieving notable performance in terms of optical contrast,\nswitching speed, cycling stability, and spectral resolution. Overall, the topic is timely\nand relevant, and the work is likely to draw attention from researchers in materials\nscience and optoelectronics. The manuscript is generally well presented, although\ncertain aspects would benefit from further clarification and discussion. Addressing\nthese points would enhance both the clarity and impact of the paper. I therefore\nrecommend that the manuscript be considered for publication in Nature\nCommunications after the authors have addressed the following questions:\n1. Question or issue: Regarding the smart window, is the ECD performance sensitive\nto the counter electrode layer? To what extent can performance be improved by\nemploying thinner counter electrodes?\nResponse: Thank you for this insightful question. To investigate the impact of the\ncounter electrode on device performance, we tested the use of extremely thin\nPEDOT:PSS and PBFDO (approximately 20 nm) films as counter electrodes. The\nresults demonstrate that the device exhibits high sensitivity to the counter electrode\nlayer, and even these thin materials significantly enhance the performance of the\nelectrochromic device (Page 9).\nRevision: In fact, even when employing extremely thin PEDOT:PSS and PBFDO films\n(~20 nm) as counter electrodes, the ECD performance is significantly enhanced\n(Supplementary Fig. 11, Supplementary Fig. 12, and Supplementary Table 1).\nSupplementary Fig. 11. Performance of the PE-OECD with an ultra-thin PBFDO\nfilm as the counter electrode. (a) Transmittance spectra at -2 V and 2 V; insects show\ndevice photographs in colored and bleached states. (b) CIE L*a*b* color coordinates\nat varying voltages. (c) Corresponding CIE xy coordinates over the same voltage range.\n(d) Transmittance response (550 nm) during coloration (-2 V) and bleaching (2 V). (e)\nOptical density change at 550 nm as a function of charge density. (f) Real-time\ntransmittance at 550 nm over multiple switching cycles.\nSupplementary Fig. 12. Performance of the PB-OECD with an ultra-thin\nPEDOT:PSS film as the counter electrode. (a) Transmittance spectra at -2 V and 2 V;\ninsects show device photographs in colored and bleached states. (b) CIE L*a*b* color\ncoordinates at varying voltages. (c) Corresponding CIE xy coordinates over the same\nvoltage range. (d) Transmittance response (550 nm) during coloration (-2 V) and\nbleaching (2 V). (e) Optical density change at 550 nm as a function of charge density.\n(f) Real-time transmittance at 550 nm over multiple switching cycles.\nSupplementary Table 1. CIE L*a*b* and CIE x*y* parameters of different OECDs at\ndifferent voltages.\nBias\nDevice L* a* b* x* y*\nvoltage\n-2 V 57.25 -1.11 -16.23 0.2513 0.2468\n-1 V 61.24 -0.92 -7.62 0.2732 0.2845\nPE-OECD 0 V 63.52 -0.8 -0.34 0.2877 0.3154\nPB-OECD 0 V 66.58 -0.42 -0.21 0.2998 0.3236\n-1 V 73.25 -0.33 0.12 0.3083 0.3349\n-2 V 80.77 -0.09 0.14 0.3169 0.3467\n-2 V 36.94 -1.13 -28.37 0.2268 0.2218\nPE-OECD\nwith ultra- -1 V 48.26 -0.84 -18.35 0.2573 0.2695\nthin 0 V 60.28 -0.72 -0.45 0.2868 0.3089\nPBFDO 1 V 73.98 -0.54 1.14 0.3037 0.3297\nfilm 2 V 80.42 -0.21 2.01 0.3193 0.3506\n-2 V 34.12 -1.26 -29.35 0.2266 0.2262\nPB-OECD\nwith ultra- -1 V 45.34 -0.91 -19.32 0.2564 0.2734\nthin 0 V 61.32 -0.81 -0.32 0.2842 0.3108\nPEDOT:PS 1 V 74.22 -0.42 1.17 0.3026 0.3312\nS film 2 V 80.56 -0.14 2.21 0.3199 0.3505\n-2 V 9.52 -2.56 -55.12 0.1989 0.1884\n-1.5 V 22.56 -1.98 -40.15 0.2205 0.2136\n-1.0 V 35.12 -1.87 -28.32 0.2446 0.2603\nFull device -0.5 V 46.25 -1.52 -17.35 0.2627 0.2921\n2. Question or issue: The authors describe the coloring mechanism as a\ndoping/dedoping process involving both ion insertion/extraction and electron transfer.\nHowever, why does the material additionally require Li+ and TFSI- ions? Does their\nincorporation affect material transparency? Please describe in detail the changes in\nmaterial during coloration and bleaching.\nResponse: Thank you for this insightful question. We would like to address the three\naspects raised as follows:\n1. Ion Insertion/Extraction: Initially, both PEDOT and PBFDO are in a doped state,\nwith PSS⁻ and H⁺ ions serving as the primary dopants, respectively. To improve\nelectrochromic (EC) performance, the materials undergo further doping (during\nbleaching) and dedoping (during coloration) throughout the EC cycling process. In\naddition to the intrinsic dopants (PSS⁻ and H⁺), TFSI⁻ and Li⁺ ions from the electrolyte\nalso participate in the doping/dedoping processes of PEDOT and PBFDO, respectively.\n2. Impact of Ion Incorporation on Transparency: The inclusion of TFSI⁻ and Li⁺\nions enhances the doping/dedoping process, resulting in more pronounced changes in\ncoloration and bleaching. Specifically, the additional ions lead to deeper coloration\n(lower transmittance) and more distinct bleaching (higher transparency) compared to\nthe initial state. This phenomenon is further illustrated in Supplementary Fig. 13.\n3. Changes During Coloration and Bleaching: In the initial state, both PEDOT and\nPBFDO are doped with PSS⁻ and H⁺ only. During the cycle, additional TFSI⁻ and Li⁺\nions are doped into the EC materials, respectively, enhancing the color change (more\ndeeper in coloration and more more transparent in bleaching). For a detailed\nunderstanding of the ion involvement and the material changes, please refer to\nEquations (1), (2), and Supplementary Fig. 10.\n3. Question or issue: The half-cell tests suggest that PEDOT and PBFDO exhibit\nsimilar electrochromic properties, please clarify the underlying reasons for this\nsimilarity. Furthermore, the use of ITO as the counter electrode appears to lead to poor\ncycling stability, attributed to charge imbalance. How is charge actually compensated\non the ITO side, and in what way does this mechanism accelerate material degradation?\nResponse: We sincerely thank the reviewer for pointing out these insightful issues.\nWe would like to address the two aspects raised as follows:\n1. Similar Electrochromic Properties: Both PEDOT and PBFDO show similar\nelectrochromic behavior primarily because they both possess favorable energetic\noffsets (symmetric open-circuit potentials and redox potentials), matched ionic\ndiffusion coefficients, and comparable charge capacitance. These shared properties\nenable their effective integration into complementary OECDs. As a result, the full\ndevice exhibit rapid optical switching, high optical contrast, excellent coloration\nefficiency, and long-term cycling stability. We have added the following explanation on\nPage 10.\nRevision: Given the exceptional electrochromic performance of complementary ECDs,\nwe investigated the intrinsic properties of EC materials. Both polymers exhibit\nfavorable energetic offsets (symmetric open-circuit and redox potentials) and matched\nionic diffusion coefficients, enabling rapid and synchronized optical switching\n(Supplementary Fig. 17 and Supplementary Fig. 18). Additionally, their high and\ncomparable charge capacitance not only promotes redox kinetics that yields large\noptical modulation and high coloration efficiency, but also ensures efficient charge\nbalance, reduces power consumption, and enhances cycling stability (Supplementary\nFig. 19)\nSupplementary Fig. 17. CV of PEDOT:PSS (a) and PBFDO (b) in 2.2 wt % LiTFSI\n(0.085 mol L-1) in PC. Reduction potential of PEDOT:PSS, oxidation potential of\nPBFDO and their open circuit potentials (P ) are indicated in the figure.\nOC\nSupplementary Fig. 18. Ionic diffusion coefficient of PEDOT:PSS and PBFDO\nfilms. (a) CV of PEDOT:PSS at different scan rates. (b) Reduction peak current plotted\nvs scan rate1/2 from (a). (c) CV of PBFDO at different scan rates. (d) Oxidation peak\ncurrent plotted vs scan rate1/2 from (c). Note: The scan rates, from lowest to highest,\nare 0.1 V s-1, 0.2 V s-1, 0.3 V s-1, and 0.4 V s-1, respectively.\nThe ionic diffusion coefficient (𝐷) of EC films can be calculated using the Randles–\nŠevčík equation:\n𝑖 = (2.687×105)𝑛3⁄2𝐴𝐷1⁄2𝐶𝑣1⁄2\n𝑝\nwhere 𝑖 is the reduction or oxidation peak current (amperes), 𝑛 is the number of\n𝑝\nelectrons transferred in a redox cycle, 𝐴 is the electrode surface area in working (cm2),\n𝐶 is the molar concentration of redox-active species (mol cm−3), 𝐷 is the diffusion\ncoefficient (cm2 s−1), and 𝑣 is the scan rate in V s−1.\nWe tested the CV curves of EC films in 2.2 wt % LiTFSI (0.085 mol L-1) in PC at\nvarious scan rates to determine the peak currents of PEDOT:PSS during reduction and\nPBFDO during oxidation. Subsequently, we plotted the peak currents against the square\nroot of the scan rate (𝑣1⁄2 ) to derive the corresponding slopes (k), which can be\nexpressed as:\n𝑘 = (2.687×105)𝑛3⁄2𝐴𝐷1⁄2𝐶\nSubstituting the measured values into the equation, we calculate 𝐷. For PEDOT:PSS,\nwith k is -0.0035 mol s-1/2, and for PBFDO, with k is -0.00346 mol s-1/2, we\nPEDOT PBFDO\nobtain:\nFor PEDOT:PSS:\n𝑘 2 1 0.0035 2\n𝐷 = ( ) = ( ) = 1.04×10−8 cm2 s−1\n2.687×105 𝑛3𝐴2𝐶2 34.25925\nFor PBFDO:\n𝑘 2 1 0.00346 2\n𝐷 = ( ) = ( ) = 1.01×10−8 cm2 s−1\n2.687×105 𝑛3𝐴2𝐶2 34.25925\nBoth polymers exhibit favorable energetic offsets (symmetric open-circuit and redox\npotentials) (Supplementary Fig. 17), and high and perfectly aligned ionic diffusion\ncoefficients, which ensure the efficiency of the redox process, contributing to the fast\nswitching speed of the complementary ECDs.\nSupplementary Fig. 19. Capacitance of PEDOT:PSS and PBFDO films. (a) CV of\nPEDOT:PSS at different scan rates. (b) Averaged anodic and cathodic current at 0 V (vs.\nAg/AgCl) plotted vs scan rate from (a). (c) CV of PBFDO at different scan rates. (d)\nAveraged anodic and cathodic current at 0.3 V (vs. Ag/AgCl) plotted vs scan rate from\n(c). Note: The scan rates, from lowest to highest, are 5 mV s-1, 10 mV s-1, 20 mV s-1,\n30 mV s-1, 40 mV s-1, 50 mV s-1, 60 mV s-1, 70 mV s-1, 80 mV s-1, 90 mV s-1, and 100\nmV s-1.\nThe specific volumetric capacitance (𝐶∗ ) of EC films was determined by recording\ncyclic voltammograms at different scan rates in 2.2 wt % LiTFSI (0.085 mol L-1) in PC.\nAs shown in Supplementary Fig. 18 (a) and (c), the non-Faradaic regions between -0.2\nV to +0.2 V and +0.2 V to +0.4 V correspond to the double-layer capacitance of\nPEDOT:PSS and PBFDO films, respectively. The capacitive behavior is confirmed by\nthe linear increase in current density with the scan rate, as described by the following\nequation:\n(𝐼 −𝐼 )⁄2 = 𝐶𝑣\n𝑎 𝑐\n𝐼 and 𝐼 represent the anodic and cathodic current densities measured at 0 V (for\na c\nPEDOT:PSS) and 0.3 V (for PBFDO), respectively, within the voltage range exhibiting\ncapacitive behavior. 𝜈 is the scan rate and 𝐶 is the volumetric capacitance. The\nspecific volumetric capacitance (𝐶∗) is calculated by dividing 𝐶 by the film thickness\n(𝑡).\nFrom the slope, the capacitances are 𝐶 = 1.78×10−3 F cm−2 and 𝐶 =\nPEDOT PBFDO\n1.96×10−3 F cm−2.\nFor PEDOT:PSS:\n𝐶 1.78×10−3 F cm−2\n𝐶∗ = PEDOT = = 207 F cm−3\nPEDOT 𝑡 86 nm\nPEDOT\nFor PBFDO:\n𝐶 1.96×10−3 F cm−2\n𝐶∗ == PBFDO = = 210 F cm−3\nPBFDO 𝑡 92 nm\nPBFDO\nIn summary, two polymers exhibit high and comparable charge capacitance: (1) High\nspecific volumetric capacitance (𝐶∗ ) allows more charge injection even at low film\nthicknesses, promoting faster redox kinetics that yield large optical modulation, high\ncoloration efficiency and more pronounced color transitions. (2) Comparable charge\ncapacitance between the two polymers ensures efficient charge balance and minimizes\nparasitic side reactions, significantly reducing the power consumption and improving\ncycling stability of the device.\n2. Charge Compensation in ITO: On the ITO side of the device, no redox reaction\noccurs, so charge compensation is achieved through the formation of an electrical\ndouble layer (EDL) (Phys. Chem. Chem. Phys. 2018, 20, 19892–19899). Since the\ncapacitance of the EDL is much lower than that generated by Faradaic reactions, more\ncharge is required on the ITO side to drive ion accumulation to balance the charge\nproduced by the redox process on the electrochromic material. To achieve this, a higher\noverall bias is needed, which in turn can accelerate the degradation of the\nelectrochromic material over time.\n4. Question or issue: While the manuscript demonstrates material identification by\nusing the OECS, the potential for hyperspectral imaging applications is only briefly\nmentioned. how the system be extended for such applications, what are the key\nchallenges in adapting the OECS for hyperspectral imaging in complex or dynamic\nenvironments? Further discussion on the scalability and flexibility of the system for\nbroader imaging tasks would enhance the manuscript’s practical relevance.\nResponse: We thank the reviewer for this valuable suggestion. We have expanded the\ndiscussion to clarify that the voltage-tunable spectral response of the electrochromic\nfilters enables sequential multi-band imaging without mechanical filters, providing a\ncompact and programmable route to hyperspectral sensing. By spatially addressing\nOECS pixel arrays under synchronized bias control, the system can be extended to real-\ntime multispectral mapping.\nWe also discussed key challenges for implementation in complex or dynamic\nenvironments, including the need for faster electrochromic switching, long-term\nmodulation stability, and reliable calibration under nonuniform illumination.\nAddressing these factors will be essential for advancing OECS devices toward\nintegrated, high-speed hyperspectral imaging systems for environmental and\nbiomedical applications. To further enhance the manuscript, the following sentences are\nadded in the main text on Page 24.\nRevision: Furthermore, the scalability of the OECS platform suggests strong potential\nfor hyperspectral imaging applications. The voltage-tunable spectral response of the\nelectrochromic filters enables sequential multi-band imaging without mechanical filters,\noffering a compact and programmable approach to hyperspectral sensing. By spatially\naddressing OECS pixel arrays under synchronized bias control, the system could be\nextended to real-time multispectral mapping. Key challenges for implementing this\nfunctionality in complex or dynamic environments include improving electrochromic\nswitching speed, maintaining long-term optical stability, and ensuring reliable\ncalibration under nonuniform illumination. Addressing these factors will be crucial for\nadvancing OECS devices toward integrated, high-speed hyperspectral imaging systems\nfor environmental and biomedical monitoring.\n5. Question or issue: In Figure 7g, the MSE of spectral reconstruction decreases\nsignificantly when four voltage steps are introduced. Could the authors elaborate on the\nunderlying reasons for this improvement? Is there a specific mechanism in the system’s\noperation that enhances accuracy with additional voltage steps? More detailed analysis\nor supporting simulations would help clarify this observation.\nResponse: We thank the reviewer for the comment. The observed decrease in MSE in\nFigure 7g with the introduction of four voltage steps is attributed to the increased\nspectral sampling density. Each voltage step slightly shifts the FP cavity resonance,\ncausing a single OPD to exhibit distinct responses under different voltages. This\nprovides the reconstruction algorithm with a richer set of measurements, thereby\nimproving reconstruction accuracy.\nTo support this explanation, we analyzed the correlation coefficients of a representative\nOPD under different applied voltages (Supplementary Fig. 32). The results show that\nadditional voltage steps effectively differentiate the OPD responses, which contributes\nto the reduction of MSE. To further clarify, we revised the following description in the\nmain text on Page 21.\nRevision: The reduction in MSE with multiple voltage steps arises from enhanced\nspectral encoding. Each voltage slightly shifts the FP cavity resonance, causing a single\nOPD to produce distinct responses. Correlation analysis of a representative OPD\n(Supplementary Fig. 32) shows that additional voltage steps improve response\ndistinguishability, providing richer measurement information for the reconstruction\nalgorithm and directly lowering the MSE.\nSupplementary Fig. 32. Enhanced distinguishability of voltage-encoded spectral\nresponses. Correlation coefficient matrices of OPD photoresponses at 14 voltage steps.\nThe decreased off-diagonal correlation with increasing number of sampling\ndemonstrates improved response distinguishability, a key factor in reducing spectral\nreconstruction error.\n6. Question or issue: The manuscript mentions the FP cavity design but provides\nlimited simulation data on the light field intensity distribution across different spacer\nthicknesses. Please provide additional simulation data to validate the microcavity\neffects at varying thicknesses? Furthermore, how does the correlation coefficient\ndistribution for each OPD pixel evolve under FP modulation?\nResponse: We thank the reviewer for the insightful comments. To further validate the\nFP microcavity effects, we performed additional optical simulations across different\nspacer thicknesses. The results show clear resonance peaks whose positions and\nintensities shift consistently with spacer variations, confirming that the FP cavities\nprovide tunable spectral selectivity (Supplementary Fig. 27).\nThese additional simulations and analyses provide a more complete validation of the\nFP microcavity design and clarify how the hybrid FP–electrochromic modulation\nenhances the OECS spectral encoding capability. To further enhance the manuscript,\nwe revised the following description in the main text on Page 18.\nRevision: To validate the microcavity effect, additional TMM simulations were\nperformed across different spacer thicknesses. The results show clear resonance peaks\nwhose positions and intensities shift consistently with spacer variations, confirming\ntunable spectral selectivity of the FP cavities (Supplementary Fig. 27).\nSupplementary Fig. 27. (a)-(d) Simulated optical field intensity distribution within FP\ncavities with Alq₃ spacer layers ranging from 75 nm to 425 nm.\nReviewer #4:\nThis manuscript focuses on the integration and hybridization of electrochromic devices\nwith disparate technologies, notably combining Electrochromic Device Enabled by p-\nn complementary conductive polymers with solar cells and spectroscopic\ninstrumentation. The work demonstrates exemplary device integration and architectural\ndesign proficiency . However, it lacks clear novelty in terms of new material design or\nmechanistic exploration. Consequently, I deem this manuscript not ideally suited for\npublication in Nature Communications. Hereby, I outline several concerns and\nrecommendations:\n1. Question or issue: The term \"All-Solid-State\" in the manuscript title is technically\ninconsistent with the electrolyte composition. According to established classification\nstandards for solid-state electrochromic devices, systems containing 46.3 wt%\npropylene carbonate (PC) solvent exceed the threshold for \"All-Solid-State\"\ndesignation (typically defined as 0 wt% solvent content). We recommend revising the\ntitle to reflect the actual material system.\nResponse: We appreciate the reviewer's insightful comment regarding the electrolyte\ncomposition. As mentioned by the reviewers, the electrolyte composition in this work\nconsists of 46 wt% PC, 43.2 wt% PEGDA, 2.2 wt% LiTFSI, and 8.3 wt% photoinitiator\n1173. Among them, PC acts as a solvent that does not participate in the crosslinking\nprocess, which facilitate the dissolution of LiTFSI, thereby enhancing ionic\nconductivity. PEGDA, as a photo-curable crosslinking monomer, undergoes radical\npolymerization under the action of photoinitiator 1173, forming a three-dimensional\nnetwork structure. Furthermore, a three-dimensional polymer network encapsulates PC\nand LiTFSI to form a all-solid-state electrolyte film.\n2. Question or issue: The x-axis label in Figure 4c contains inaccuracies. Please\nrigorously verify and correct all axis designations to ensure alignment with the plotted\ndata parameters.\nResponse: We sincerely appreciate the reviewer for pointing out the format issue in\nFigure 4c. We have made the necessary corrections in the Figure 4c .\nRevision :\n.\nFig. 4c. Dynamic transmittance at 550 nm measured at the center and edge of the device\nduring a full switching cycle (from −2 V to 2 V).\n3. Question or issue: The switching times (τc/τb) calculated from chronoamperometry\n(CA) curves in Figure 3d and Supplementary Information contradict standardized\nevaluation protocols. Electrochromic switching time must be derived from in-situ\ntransmittance spectroscopy.\nResponse: We sincerely thank the reviewer for raising important points regarding the\nswitching times. We have replaced all CA curves with in situ transmittance-time curves.\nSpecifically, we have made modifications in Figure 3d, Supplementary Fig. 8d,\nSupplementary Fig. 9d, Supplementary Fig. 11d, and Supplementary Fig. 12d,\nrespectively.\nRevision:\n4. Question or issue: The Coloration Efficiency in Figure 3e and Supplementary\nInformation require corresponding in-situ transmittance spectroscopy. Authors should\nprovide complete spectral datasets (ΔT% vs Time) at relevant wavelengths to\nsubstantiate the reported efficiency calculations.\nResponse: We appreciate your kind suggestion. In response, we have incorporated this\nclarification into the main text (Page 10) and provided complete spectral datasets (ΔT%\nvs Time) at 550 nm in Supplementary Fig. 14 a.\nRevision : The transmission spectrum (at 550 nm), charge accumulation (Q) and optical\ndensity (ΔOD) variations over time are shown in Supplementary Fig. 14.\nSupplementary Fig. 14a. Time-dependent transmission at 550 nm recorded during the\ncoloration process.\n5. Question or issue: Counter Electrode Design Flaw: The device architecture\nemploying ITO as a counter electrode in Supplementary Figs. 8–9 exhibits fundamental\ndesign limitations. ITO's narrow electrochemical stability window and propensity for\nion accumulation compromise device cyclability—a critical oversight given the\nemphasis on integrated systems.\nResponse: We sincerely thank the reviewer for the thoughtful comment regarding the\nemployment of ITO as a counter electrode. The reviewer correctly pointed out that\nemploying ITO as a counter electrode may result in ion accumulation at the electrode-\nelectrolyte interface, forming an electrical double layer (EDL) to compensate for the\ncharge imbalance on the EC side (Phys. Chem. Chem. Phys. 2018, 20, 19892–19899).\nHowever, the relatively high operating voltage required for such a configuration can\nlead to accelerated EC material degradation. In this study, we intentionally employ ITO\nas a counter electrode to systematically demonstrate the performance advantages of our\nproposed complementary electrochromic architecture. This approach allows for a direct\ncomparison of charge compensation mechanisms while highlighting the superior\nstability and efficiency of the complementary structure under identical testing\nconditions.\n6. Question or issue: The gradual self-bleaching without applied bias—termed as\n\"memory effect\" in the manuscript—reflects poor bistability. This behavior signifies\ninsufficient charge trapping/retention, diminishing viability for low-energy-display\napplications. The authors should rephrase to accurately describe this performance\nlimitation and address the underlying reasons.\nResponse: Thank you for your valuable comment about bistability of the OECD.\nConductive polymers often demonstrate inferior memory effects in electrochromic\napplications due to the metastable nature of their oxidized/reduced states. When the\nHOMO energy level of the polymer in its dedoped state exceeds that of the electrolyte's\nLUMO, thermodynamically driven charge leakage occurs, leading to spontaneous\nelectron back-transfer. In this work, although this effect is unfavorable for low-energy\ndisplays, it demonstrates tremendous potential for the utilization of this adaptive erasure\neffect for building-integrated photovoltaics.\n7. Question or issue: While the ECD-solar cell integration in Figure 5f improves\nenergy efficiency, the compromised optical performance (reduced maximum\ntransmittance and neutral colors) negates practical utility. Clarify whether this trade-off\njustifies integration versus standalone implementations.\nResponse: Thank you for the insightful comment. For the OECD, the device transitions\nbetween a highly transparent neutral state and a deep blue hue. For the ST-OSC,\nthe module exhibits a pale blue color due to the presence of the Ag coating.\nConsequently, the integrated device transitions from pale blue to deep blue. Although\nthe initial state is not neutral, it remains highly transparent. In our future work, we will\noptimize the ST-OSC color and further increase transparency.\n8. Question or issue: While this manuscript demonstrates technical proficiency in\nhybridizing multiple functional systems, it exhibits critical deficiencies in two\nfundamental dimensions: (i) Absence of novel material design and mechanistic\ninvestigation, (ii) Unsubstantiated logical coherence between disparate application\nextensions—exemplified by the integration of self-powered smart windows and organic\nelectrochromic spectrometers.\nResponse: Thank you for this insightful question. We would like to answer these\nquestions as follows:\n1. Material Design and Mechanistic Investigation: PBFDO, as a highly transparent\nand highly conductive n-type polymer, has been demonstrated in previous work for\napplications such as transparent electrodes (J. Am. Chem. Soc. 2023, 145, 3706−3715),\nthermoelectrics (Angew. Chem. Int. Ed. 2025, 64, e202415349), organic\nelectrochemical transistors (Angew. Chem. Int. Ed. 2025, 64, e202415349), and\ndisplays (Nature Electronics, 2024, 7, 1158–1169). However, its use in electrochromic\nsmart windows and spectrometers has received little attention. Here, we employ it as\nthe aodic electrochromic materials, forming a high-performance complementary OECD\nwith p-type PEDOT:PSS. Furthermore, we explore the underlying reasons behind the\ndevice's high performance. The two conductive polymers exhibit favorable energetic\noffsets—including symmetric open-circuit potentials and redox potentials—as well as\ntheir matched ionic diffusion coefficients, and comparable charge capacitance. These\nproperties enable their effective integration into complementary OECDs, resulting in\nrapid optical switching, high optical contrast and coloration efficiency, low energy\nconsumption, and exceptional long-term cycling stability. We have incorporated this\nclarification into the main text (Page 10) to better highlight material advantages of our\ndevice.\nRevision : Given the exceptional electrochromic performance of complementary ECDs,\nwe investigated the intrinsic properties of EC materials. Both polymers exhibit\nfavorable energetic offsets (symmetric open-circuit and redox potentials) and matched\nionic diffusion coefficients, enabling rapid and synchronized optical switching\n(Supplementary Fig. 17 and Supplementary Fig. 18). Additionally, their high and\ncomparable charge capacitance not only promotes redox kinetics that yields large\noptical modulation and high coloration efficiency, but also ensures efficient charge\nbalance, reduces power consumption, and enhances cycling stability (Supplementary\nFig. 19)\nSupplementary Fig. 17. CV of PEDOT:PSS (a) and PBFDO (b) in 2.2 wt % LiTFSI\n(0.085 mol L-1) in PC. Reduction potential of PEDOT:PSS, oxidation potential of\nPBFDO and their open circuit potentials (P ) are indicated in the figure.\nOC\nSupplementary Fig. 18. Ionic diffusion coefficient of PEDOT:PSS and PBFDO\nfilms. (a) CV of PEDOT:PSS at different scan rates. (b) Reduction peak current plotted\nvs scan rate1/2 from (a). (c) CV of PBFDO at different scan rates. (d) Oxidation peak\ncurrent plotted vs scan rate1/2 from (c). Note: The scan rates, from lowest to highest,\nare 0.1 V s-1, 0.2 V s-1, 0.3 V s-1, and 0.4 V s-1, respectively.\nThe ionic diffusion coefficient (𝐷) of EC films can be calculated using the Randles–\nŠevčík equation:\n𝑖 = (2.687×105)𝑛3⁄2𝐴𝐷1⁄2𝐶𝑣1⁄2\n𝑝\nwhere 𝑖 is the reduction or oxidation peak current (amperes), 𝑛 is the number of\n𝑝\nelectrons transferred in a redox cycle, 𝐴 is the electrode surface area in working (cm2),\n𝐶 is the molar concentration of redox-active species (mol cm−3), 𝐷 is the diffusion\ncoefficient (cm2 s−1), and 𝑣 is the scan rate in V s−1.\nWe tested the CV curves of EC films in 2.2 wt % LiTFSI (0.085 mol L-1) in PC at\nvarious scan rates to determine the peak currents of PEDOT:PSS during reduction and\nPBFDO during oxidation. Subsequently, we plotted the peak currents against the square\nroot of the scan rate (𝑣1⁄2 ) to derive the corresponding slopes (k), which can be\nexpressed as:\n𝑘 = (2.687×105)𝑛3⁄2𝐴𝐷1⁄2𝐶\nSubstituting the measured values into the equation, we calculate 𝐷. For PEDOT:PSS,\nwith k is -0.0035 mol s-1/2, and for PBFDO, with k is -0.00346 mol s-1/2, we\nPEDOT PBFDO\nobtain:\nFor PEDOT:PSS:\n𝑘 2 1 0.0035 2\n𝐷 = ( ) = ( ) = 1.04×10−8 cm2 s−1\n2.687×105 𝑛3𝐴2𝐶2 34.25925\nFor PBFDO:\n𝑘 2 1 0.00346 2\n𝐷 = ( ) = ( ) = 1.01×10−8 cm2 s−1\n2.687×105 𝑛3𝐴2𝐶2 34.25925\nBoth polymers exhibit favorable energetic offsets (symmetric open-circuit and redox\npotentials) (Supplementary Fig. 17), and high and perfectly aligned ionic diffusion\ncoefficients, which ensure the efficiency of the redox process, contributing to the fast\nswitching speed of the complementary ECDs.\nSupplementary Fig. 19. Capacitance of PEDOT:PSS and PBFDO films. (a) CV of\nPEDOT:PSS at different scan rates. (b) Averaged anodic and cathodic current at 0 V (vs.\nAg/AgCl) plotted vs scan rate from (a). (c) CV of PBFDO at different scan rates. (d)\nAveraged anodic and cathodic current at 0.3 V (vs. Ag/AgCl) plotted vs scan rate from\n(c). Note: The scan rates, from lowest to highest, are 5 mV s-1, 10 mV s-1, 20 mV s-1,\n30 mV s-1, 40 mV s-1, 50 mV s-1, 60 mV s-1, 70 mV s-1, 80 mV s-1, 90 mV s-1, and 100\nmV s-1.\nThe specific volumetric capacitance (𝐶∗ ) of EC films was determined by recording\ncyclic voltammograms at different scan rates in 2.2 wt % LiTFSI (0.085 mol L-1) in PC.\nAs shown in Supplementary Fig. 18 (a) and (c), the non-Faradaic regions between -0.2\nV to +0.2 V and +0.2 V to +0.4 V correspond to the double-layer capacitance of\nPEDOT:PSS and PBFDO films, respectively. The capacitive behavior is confirmed by\nthe linear increase in current density with the scan rate, as described by the following\nequation:\n(𝐼 −𝐼 )⁄2 = 𝐶𝑣\n𝑎 𝑐\n𝐼 and 𝐼 represent the anodic and cathodic current densities measured at 0 V (for\na c\nPEDOT:PSS) and 0.3 V (for PBFDO), respectively, within the voltage range exhibiting\ncapacitive behavior. 𝜈 is the scan rate and 𝐶 is the volumetric capacitance. The\nspecific volumetric capacitance (𝐶∗) is calculated by dividing 𝐶 by the film thickness\n(𝑡).\nFrom the slope, the capacitances are 𝐶 = 1.78×10−3 F cm−2 and 𝐶 =\nPEDOT PBFDO\n1.96×10−3 F cm−2.\nFor PEDOT:PSS:\n𝐶 1.78×10−3 F cm−2\n𝐶∗ = PEDOT = = 207 F cm−3\nPEDOT 𝑡 86 nm\nPEDOT\nFor PBFDO:\n𝐶 1.96×10−3 F cm−2\n𝐶∗ == PBFDO = = 210 F cm−3\nPBFDO 𝑡 92 nm\nPBFDO\nIn summary, two polymers exhibit high and comparable charge capacitance: (1) High\nspecific volumetric capacitance (𝐶∗ ) allows more charge injection even at low film\nthicknesses, promoting faster redox kinetics that yield large optical modulation, high\ncoloration efficiency and more pronounced color transitions. (2) Comparable charge\ncapacitance between the two polymers ensures efficient charge balance and minimizes\nparasitic side reactions, significantly reducing the power consumption and improving\ncycling stability of the device.\n2. Logical Coherence Between Smart Windows and Spectrometers: We agree that\nthe manuscript would benefit from a clearer articulation of the unifying concept\nunderlying these two systems. Both applications are built upon the same fundamental\nproperty of organic electrochromic devices (OECDs), their capability to modulate\noptical properties in a controllable, voltage-dependent manner. By highlighting this\nshared technological foundation, we emphasize that the smart window and the\nminiaturized spectrometer represent complementary demonstrations of the versatility\nand scalability of electrochromic materials across different application domains. To\naddress the reviewer’s concern, we have carefully revised the manuscript to strengthen\nthe logical linkage between the two applications:\n(1). Introduction: We have clarified on Page 4 that the manuscript presents two distinct\nbut technologically linked applications of OECDs: a self-powered smart window and a\nminiaturized spectrometer, both of which utilize voltage-controlled modulation of\noptical properties.\nRevision 1: This work presents two applications of OECDs, a self-powered smart\nwindow and a miniaturized spectrometer, both based on voltage-controlled modulation\nof optical properties. The smart window enables adaptive light regulation for energy-\nefficient buildings, while the spectrometer achieves precise light filtering and spectral\ndetection in a compact, portable format. Together, these results demonstrate a scalable\nelectrochromic platform that bridges large-area energy management with high-\nresolution optical sensing, positioning OECDs as a foundational technology for next-\ngeneration adaptive optoelectronics and real-time environmental monitoring.\n(2). End of Smart Window Section: In the manuscript Page 16, we added discussion\non how the large-area, energy-efficient performance of the smart window illustrates the\npotential of electrochromic devices for integration into real-world environments\nrequiring sustainability and adaptive light regulation.\nRevision 2: By integrating the OECD with a high-efficiency ST-OSC, the system\nautonomously controls optical transmission while lowering indoor temperature,\nunderscoring its potential for large-scale, sustainable deployment.\n(3). Miniaturized Spectrometer Section: In the manuscript Page 17, we clarified the\ncontrast by highlighting that, while the smart window addresses large-scale energy\nmanagement, the miniaturized spectrometer applies the same materials to compact,\nprecise spectral sensing, demonstrating adaptability at a different scale.\nRevision 3: In contrast to the large-area application of electrochromic devices in smart\nwindows, the miniaturized spectrometer targets compact, low-cost, high-resolution\nspectral sensing. Instead of regulating heat and light across a large surface, the same\nvoltage-dependent optical modulation is used to selectively filter and detect spectral\ninformation with high precision in a portable device. Building on the scalability, tunable\noptics, and self-powered operation demonstrated in OECD-based smart windows, we\ntranslate the platform into chip-scale, voltage-programmable spectrometers. By\nmonolithically integrating electrochromic filters with high-sensitivity OPDs, these\ndevices provide reconfigurable spectral filtering and computational reconstruction.\nThis transition from meter-scale dynamic windows to millimeter-scale photonic sensors\nunderscores the versatility and cross-scale adaptability of the PEDOT:PSS–PBFDO\nelectrochromic platform.\n(4). Conclusion Section: We further emphasize that, although these applications target\ndifferent functions, they are inherently connected. The progress achieved in large-scale\nsmart window integration informs the development of smaller, high-resolution optical\ndevices, and vice versa, reinforcing the broad applicability of electrochromic materials\nin multifunctional optoelectronic systems (Page 26).\nRevision 4: All three devices, the standalone OECD, the ST-OSC-powered smart\nwindow, and the on-chip OECS, share the same electrochromic material system but are\ntailored for distinct functions. The OECD benchmarks device performance, the ST-OSC\nsmart window demonstrates scalable, self-powered light and heat regulation, and the\non-chip OECS enables precise spectral sensing. Together, they showcase the platform’s\nscalability, functional versatility, and potential for technology transfer from\nfundamental materials to integrated systems.\nPoint-by-point response letter accompanying our Re-Submission of:\nAll-Solid-State Electrochromic Device Enabled by p-n\nComplementary Conductive Polymers: From Self-Powered\nSmart Window to Miniaturized Spectrometer\nManuscript ID: NCOMMS-25-59872A\nDear Reviewers,\nWe thank you for the conscientious peer review of our manuscript and the very helpful\ncriticism. In response to your comments, we have incorporated the suggested changes.\nIn the document below, we comment on all the concerns and points raised by the\nreviewers. For easy readability we visually structured our response as follows:\nThe comments and points of the referees are copied in black color.\nOur response is colored blue.\nFurthermore, we cite parts from the revised manuscript or the revised Supplementary\nData to afford a quick impression of the improvements and changes made to the text.\nThese citations are indicated by orange text.\nWe hope that we fully answered all the mentioned concerns and issues.\nSincerely,\nFei Huang\nReviewer #1:\nAs I suggested last time, it is not coherent to mix the two applications in one paper.\nAlso, the organic electrochromic cannot provide enough spectral information for\nreconstructive spectrometers, which means the results will be extremly unstable. So my\ncomment is still rejection for this round review.\nResponse: We respect the reviewer’s comments. In response to the concerns raised,\nwe provide the following clarifications:\n1. Logical Linkage Between the Two Applications: We emphasize that these are not\ntwo unrelated applications, but rather dual functionalities emerging from a unified all-\nsolid-state p-n complementary electrochromic platform. Both the smart window and\nminiaturized spectrometer leverage voltage-controlled ion/electron injection/extraction\nto modulate optical states, demonstrating the versatility of this shared architecture.\nSpecifically, for smart windows, we exploit voltage-dependent transmittance\nmodulation to dynamically regulate solar spectrum, enabling optimized energy\nefficiency. For spectrometers, these distinct spectral response curves serve as rich\nsampling basis for computational reconstruction, facilitating the development of\nultracompact, high-resolution spectral detection systems.\nRecent literature shows that electrochromic optical modulation itself can serve as a\nspectral encoding mechanism for on-chip spectroscopy1,2. For example, Tian1 et al.\ndeveloped an electrochromic computational spectrometer basing polarizers/inorganic\ncomplementary electrochromic device that uses voltage-dependent transmission\nchanges to modulate spectral response units. Compared with their work, our device\nadopts a more straightforward and efficient strategy, requiring no additional\npolarization device. Instead, we directly couple electrochromic modulation with a FP\noptical cavity, where voltage tuning induces transmission changes that shift the cavity\nresonance. This hybrid strategy can yield enhanced wavelength selectivity and deeper\ntunability. Notably, our total thickness of the cavity stack is only tens to hundreds of\nnanometers, making it inherently compatible with chip-level integration and enabling\ncompact miniaturized spectroscopic functionality.\nIn summary, our work presents two applications of organic electrochromic devices\n(OECDs), a centimeter-scale self-powered smart window and a millimeter-scale\nminiaturized spectrometer, both based on voltage-controlled modulation of optical\nproperties. The smart window enables adaptive light regulation for energy-efficient\nbuildings, while the spectrometer achieves precise light filtering and spectral detection\nin a compact, portable format. These are not disparate applications, but rather multiscale\nmanifestations of the same fundamental electrochromic mechanism, spanning from\nmacroscopic energy modulation to microscopic spectral sampling. To enhance the\npersuasiveness of our manuscript, we have added additional discussion in Page 18.\nRevision: The FP cavity is nanometer-scale, eliminating the need for additional optical\ncomponents and enabling a compact all-solid-state spectral device.\n2. Additional Spectral Information Supplementary: In response to the reviewer’s\nconcern about insufficient spectral information, we have supplemented the relevant\nexperiments, including EQE responses and Gaussian white noise test, and made\ncorresponding revisions in pages 20 and 22, respectively. We hope these clarifications\nand the newly added experimental data address the reviewer’s concerns. We sincerely\nappreciate the reviewer’s continued evaluation and valuable suggestions.\nRevision: (1) Different pixels measured at 14 bias voltages exhibit distinct EQE\nresponses (Supplementary Fig. 31), enabling sufficient spectral information for\nreconstructive spectroscopy.\nSupplementary Fig. 31. Full EQE spectra of 14 voltage-modulated sampling states\n(from –2 V to +2 V). These spectra serve as the sampling basis for spectral\nreconstruction.\n(2) Using 14 voltage-modulated cavity states as sampling points, the spectrometer\nmaintains < 0.005 MSE in spectrum reconstruction even when 20% Gaussian white\nnoise is added (Supplementary Fig. 33).\nSupplementary Fig. 33. Noise-robustness test of the OECS. Reconstructed spectrum\n(a) and corresponding MSE (b) of a cold-white LED under different levels of Gaussian\nwhite noise added to the spectral sampling curves (0%, 2%, 5%, 10%, 20%). Even at\n20% noise level, the MSE remains < 0.005, demonstrating excellent robustness in\nspectral reconstruction.\nReviewer #2:\nThe authors did an excellent job of responding to my comments - this paper should be\npublished.\nResponse: Thank you for your thoughtful review. We appreciate that you found our\nresponses satisfactory and your positive recommendation for publication.\nReviewer #3:\nThe authors have effectively addressed my previous concerns. Though the two parts in\nthis work exhibit not strong relationship, I still think the authors have presented a novel\nextention of this material to the spectrometer besides the smart windows, hence I\nbelieve the manuscript can be accepted for publication after their revision.\nResponse: We sincerely appreciate the reviewer's recognition of our efforts in\naddressing the previous concerns. Thank you for your constructive feedback and for\nsupporting the publication of our manuscript.\nReviewer #4:\nI have carefully evaluated the authors' responses to the review comments. Regrettably,\nthe authors' responses fail to adequately address the concerns raised, and therefore\nI cannot recommend this manuscript for publication in its current form. My specific\nreservations are as follows:\n1. Question or issue: Ambiguous Definition of \"All-Solid-State\". In the initial review,\nI explicitly highlighted the ambiguity in the authors' definition of \"all-solid-state\"\ndevices. However, the revised manuscript retains the same problematic description\nwithout providing rigorous justification. The current configuration combining liquid\nelectrolytes with polymer matrices should be more appropriately classified as quasi-\nsolid-state or hybrid systems, rather than true all-solid-state devices. I strongly urge the\nauthors to consult authoritative references on all-solid-state electrolytes to clarify this\nfundamental distinction. Such terminological inaccuracies risk misleading the\nelectrochemical community regarding device classification standards.\nResponse: We appreciate the reviewer's insightful comment again regarding the\nelectrolyte aspects. To address the reviewer’s concern, we have carefully consulted the\nauthoritative references on all-solid-state electrolytes and present our views as follows:\n1. The General Definition of Solid-State Electrolytes: As the reviewers have pointed\nout, solid-state electrolytes represent a distinct class of ion-conductive materials that\noperate exclusively in the solid phase, devoid of liquid solvents. This inherent solidity\nand absence of solvent mediation fundamentally differentiate them from liquid or gel-\nbased electrolytes (quasi-solid-state), which rely on mobile liquid phases for ionic\ntransport. Solid-state electrolytes can be structurally classified into three primary\ncategories3: (1) inorganic solid electrolytes, encompassing oxide-based (e.g., LLZO,\nLATP) and sulfide-based (e.g., Li₁₀GeP₂S₁₂, Li₆PS₅Cl) materials; (2) polymer-based\nsolid electrolytes, such as poly(ethylene oxide) (PEO) systems; and (3) composite solid\nelectrolytes, which integrate inorganic fillers within a polymer matrix to synergize their\nrespective advantages. However, emerging studies challenges the conventional\nparadigm that “solid-state electrolytes are entirely devoid of liquid components”,\nparticularly in the field of solid-state batteries (SSBs).\n2. The Definition of Solid-State Electrolytes in (SSBs): According to the\nInternational Union of Pure and Applied Chemistry (IUPAC), solid polymer\nelectrolytes are defined as “electrically conducting solution of a salt in a polymer”4.\nThis classification explicitly recognizes ionically conducting polymers as solid\nelectrolytes, even though their conduction mechanism depends on a solution-phase\nprocess—directly challenging rigid “solid-only” paradigms in battery discourse. In\naddition, based on statements from authoritative experts, such as Tarascon and Armand5\n(“Solid-state batteries include polymer electrolytes (dry or gel) and ceramic\nelectrolytes”), the Manthiram6 (“Solid-state batteries may employ inorganic solids, dry\npolymers, or gel polymers”), and the Archer team7 (“The introduction of plasticizer into\nthe polymer skeleton is a key event in the development of solid polymer electrolytes\n(SPEs)”), as well as the consensus among other researchers8-11, SSBs inherently include\npolymer electrolytes, whether dry or gel-based. Building upon these considerations,\nGuo3 et al. proposed a more engineering-practical definition of SSBs: systems systems\nin which the electrolyte remains nonflowable under operating conditions and retains\ndimensional stability throughout cycling. This definition accommodates polymer\nelectrolyte systems containing plasticizers, provided they establish a stable, non-\nflowing continuous phase, a criterion consistent with prevailing academic and industrial\ninterpretations of solid electrolytes12. Accordingly, the core criterion for determining\n“solid-state” should not rigidly focus on the presence or absence of liquid phases.\nInstead, emphasis should be placed on the functional characteristics of the electrolyte\nsystem under actual operating conditions, particularly two key parameters: interfacial\nstability and structural integrity.\n3. The Definition of Solid-State Electrolytes in Electrochromic devices (ECDs): In\nthe field of ECDs, researchers typically classify electrolytes into three categories: (1)\nLiquid electrolytes13-15. These electrolytes are generally composed of a mixture of\nwater/organic solvents (such as PC, ACN, etc.) and ionic salts (such as Li+, Na+, K+,\netc.); (2) Gel electrolytes16-18. These are typically formed by mixing a liquid phase with\na polymer matrix (PVA, PVB, PMMA, etc.), exhibiting a certain degree of fluidity; (3)\nSolid-state polymer electrolytes (SPE)19-22. Which are formed by adding photoinitiator\nmonomers (e.g., HEA, MMA, PEGDA, PEGMA etc.) and photoinitiators (such as\nphotoinitiators 1173, 184, etc.) to liquid or gel phases. The mixture then polymerizes\nunder UV light irradiation to form electrolyte films, which is entirely solid and exhibits\nno fluidity. A more detailed summary is shown in Table 1. More importantly, as shown\nin the Fig. 1, we have prepared a highly transparent, solid-state, and flexible electrolyte\nfilm after photopolymerization.\nTable 1. Recent studies on electrochromic devices concerning electrolyte selection.\nElectrolyte Electrolyte\nDevice structure Ref.\ntype composition\nWater + ZnCl +\nZnI\nCuSO + H SO\n4 2 4\nFTO/P-NiO/Electrolyte/Carbon paper on FTO Liquid Water + KOH 15\nPC + acetonitrile +\nPET/ITO/Q-PHI WO / Electrolyte/NiO/ITO/PET Gel 16\n18 49\nPMMA\nPET/Ag grid/PEDOT:PSS/WO -\n2 4\nPEDOT:PSS/Electrolyte/ITO/PET\nPC/NaClO +\npropylene glycol\nmethyl ether\nITO/WO / Electrolyte/PEDOT:PSS/ITO SPE acetate + 1,2- 19\n3\ndimethyl-3-\npropylimidazoliu\nm iodide +\nFerrocene\nPEGMA + HMPP\nFTO/WO -CNTs/Electrolyte/PANI /FTO SPE 20\n3\n+ LiTFSI + SN\nPC + PEGMA +\nITO/n-PBDF/SPE/PEDOT:PSS/ITO SPE 21\nHMP + TBATFSI\nPC + PEGDA +\nPBDF-deposited glass/ECP/SPE/VO /ITO SPE 22\nx\nHMPP + LiTFSI\nFig. 1. a Electrolyte gel prior to light curing. b-c Solid-state, robust and flexible\npolymer electrolyte film after light curing.\n2. Question or issue: Unsubstantiated \"Memory Effect\" Claim. The authors'\npersistence in using the term \"memory effect\" remains scientifically untenable. Similar\nto battery self-discharge mechanisms, this analogy fundamentally contradicts the\nessential bistable characteristics of electrochromic devices (ECDs). The hallmark of\nhigh-performance ECDs lies in their ability to maintain optical states without sustained\nvoltage application-a critical energy-saving feature that distinguishes active\nelectrochromic regulation from passive photochromic/photothermal systems. Although\nthe proposed \"memory effect\" might enable self-regulation in ST-OSC-powered smart\nwindows, it would inevitably undermine the fundamental advantages of standalone\nOECD and on-chip OECS configurations by causing optical instability during power-\noff conditions. The authors must either provide comprehensive experimental evidence\nsupporting this unconventional mechanism or remove such speculative claims entirely.\nResponse: Thanks for your insightful comment regarding the “memory effect” of the\nOECDs. As pointed out, bistability is also one of the key indicators for evaluating ECDs\nperformance. Initially, our goal was to leverage the memory effect of the OECDs to\ncreate an adaptive integrator (ST-OSC-OECDs). This application is widely utilized in\nviologen systems, as they exhibit excellent self-erasure effects23-27, typically reverting\nto their bleached state within minutes when voltage is disconnected. Leveraging this,\nin 2021, Ling23 et al. designed two alkynyl groups viologens and combined them with\nperovskite solar cell. The integrated devices demonstrates excellent photosensitivity\nand can automatically switch between bleached and colored state to adjust light\nabsorption with variable surrounding light intensity in real-time swiftly, which establish\nsignificant potentials for applications as modern all-day intelligent windows. However,\nas shown in Supplementary Fig. 25, our OECD exhibits relatively good static stability.\nAfter removing the voltage, the device's transmittance increased by 26% within 2 hours\n(from 4% to 30%), making it not ideal enough for adaptive optical devices. In summary,\nwe decided to follow the reviewers' suggestions and deleted this claim (Page 16 and\nSupplementary Fig. 25) to enhance the manuscript's scientific rigor and coherence.\nMoreover, in our future work, we will focus on enhancing the bistability of the OECDs.\nRevision: Beyond enabling self-powering, the system exhibits promising dynamic\nadaptation to natural lighting. The OECD shows a “memory effect”: after applying and\nremoving a −2 V bias, its transmittance gradually increases from 4% to 24% within the\nfirst hour (at a rate of 0.33% per minute), and further to 30% in the following hour (0.1%\nper minute) (Supplementary Fig. 25). This slow relaxation mimics the natural\nprogression of daylight intensity, enabling passive, gradual darkening as sunlight\nintensifies in the morning and increased transparency towards evening, which reduces\ncontrol complexity and enhances energy efficiency.\nSupplementary Fig. 25. Memory behavior of the complementary OECD for coloration.\nReferences\n1. Tian, M. et al. Miniaturized on-chip spectrometer enabled by electrochromic\nmodulation. Light Sci. Appl. 13, 278 (2024).\n2. Zhu, Y. et al. Flexible and High-Performance Solution-Processable Single-Detector\nOrganic Spectrometer. Adv. Mater. 37, 2502608 (2025).\n3. Li, Z., Peng, S., Wei, L. & Guo, X. Why Will Polymers Win the Race for Solid-\nState Batteries? Adv. Sci.12, e10481 (2025).\n4. Kaiser, J. & Chalk, S. J. in IUPAC Compendium of Chemical Terminology, 5th ed.,\nInternational Union of Pure and Applied Chemistry, https:\n//doi.org/10.1351/goldbook.ST07227.\n5. Tarascon, J. M. & Armand, M. Issues and challenges facing rechargeable lithium\nbatteries. Nature 414, 359-367 (2001).\n6. Manthiram, A., Yu. X. & Wang, S. Lithium battery chemistries enabled by solid-\nstate electrolytes. Nat. Rev. Mater. 2, 16103 (2017).\n7. Zhao, Q., Stalin, S., Zhao, C. & Archer, L. A. Designing solid-state electrolytes for\nsafe, energy-dense batteries. Nat. Rev. Mater. 5, 229-252 (2020)\n8. Quartarone, E. & Mustarelli, P. Electrolytes for solid-state lithium rechargeable\nbatteries: recent advances and perspectives. Chem. Soc. Rev. 40, 2525-2540 (2011).\n9. Kang, Q. et al. Engineering the Structural Uniformity of Gel Polymer Electrolytes\nvia Pattern-Guided Alignment for Durable, Safe Solid-State Lithium Metal\nBatteries. Adv. Mater. 35, 2303460 (2023).\n10. An, H. et al. Hybrid electrolyte enables solid-state sodium batteries sustaining\n50,000 cycles. Nat. Sustain. 8, 661–671 (2025).\n11. Wang, D. et al. Low-Cost, High-Strength Cellulose-based Quasi-Solid Polymer\nElectrolyte for Solid-State Lithium-Metal Batteries. Angew. Chem. Int. Ed. 62,\ne202302767 (2023).\n12. Huo, H. & Janek, J. Solid-state batteries: from ‘all-solid’ to ‘almost-solid’. Natl.\nSci. Rev.10, nwad098 (2023).\n13. Li, S. et al. Electrochromism via reversible electrodeposition of solid iodine. Nat.\nCommun. 16, 724 (2025).\n14. Jia, F. et al. Electrochromic windows with fast response and wide dynamic range\nfor visible-light modulation without traditional electrodes. Nat. Commun. 15, 6110\n(2024).\n15. Hu, C. et al. Crystal reconstructed cubic nickel oxide with energetic reactive\ninterfaces for exceptional electrochromic smart windows. Mater. Horiz. 12, 1962-\n1970 (2025).\n16. Li, P. et al. Nanostructured Quasiplanar Heterointerface for a Highly Stable and\nUltrafast Switching Flexible Inorganic Electrochromic Smart Window. Nano Lett.\n25, 2342−2349 (2025).\n17. Huang, Z. et al. An Efficient and Flexible Bifunctional Dual-Band Electrochromic\nDevice Integrating with Energy Storage. Nano-Micro Lett. 17, 98 (2025).\n18. Cai, G. et al. Direct inkjet-patterning of energy efficient flexible electrochromics.\nNano Energy 49, 147-154 (2018).\n19. Shao, Z. et al. All-solid-state proton-based tandem structures for fast-switching\nelectrochromic devices. Nat. Electron. 5, 45-52 (2022).\n20. Li, R. et al. A Local-Dissociation Solid-State Polymer Electrolyte with Enhanced\nLi+ Transport for High-Performance Dual-Band Electrochromic Smart Windows.\nAdv. Funct. Mater. 35, 2419357 (2025).\n21. Ke, Z. et al. Highly Conductive and Solution-Processable n-Doped Transparent\nOrganic Conductor. J. Am. Chem. Soc. 145, 3706-3715 (2023).\n22. Song, I. et al. An n-doped capacitive transparent conductor for all-polymer\nelectrochromic displays. Nat. Electron. 7, 1158-1169 (2024).\n23. Ling, H., Wu, J., Su, F., Tian, Y. & Liu, Y. J. Automatic light-adjusting\nelectrochromic device powered by perovskite solar cell. Nat. Commun. 12, 1010\n(2021).\n24. Wu, X. et al. Synergistic Interaction of Dual-Polymer Networks Containing\nViologens-Anchored Poly(ionic liquid)s Enabling Long-Life and Large-Area\nElectrochromic Organogels. Small 19, 2301742 (2023).\n25. Kao, S. et al. Thermally Cured Dual Functional Viologen-Based All-in-One\nElectrochromic Devices with Panchromatic Modulation. ACS Appl. Mater.\nInterfaces 8, 4175-4184 (2016).\n26. Zhang, Y. et al. Ultrastable Viologen Ionic Liquids-Based Ionogels for Visible\nStrain Sensor Integrated with Electrochromism, Electrofluorochromism, and Strain\nSensing. CCS Chem. 5, 1917-1930 (2023).\n27. Zhou, X. et al. Viologen derivatives with extended π-conjugation structures: From\nsupra-/molecular building blocks to organic porous materials. Chin. Chem. Lett. 31,\n1757-1767 (2020)."}, {"round": 2, "reviewer_comments": {"reviewer_1": "As I suggested last time, it is not coherent to mix the two applications in one paper. Also, the organic electrochromic cannot provide enough spectral information for reconstructive spectrometers, which means the results will be extremly unstable. So my comment is still rejection for this round review.", "reviewer_2": "The authors did an excellent job of responding to my comments - this paper should be published.", "reviewer_3": "The authors have effectively addressed my previous concerns, though the two parts in this work exhibit not strong relationship. i till think the authors have presented a novel extention of this material to the spectrometer besides the smart windows, hence I believe the manuscript can be accepted for publication after their revision.", "reviewer_4": "I have carefully evaluated the authors' responses to the review comments. Regrettably, the authors' responses fail to adequately address the concerns raised, and therefore I cannot recommend this manuscript for publication in its current form. My specific reservations are as follows:\n1. Ambiguous Definition of \"All-Solid-State\". In the initial review, I explicitly highlighted the ambiguity in the authors' definition of \"all-solid-state\" devices. However, the revised manuscript retains the same problematic description without providing rigorous justification. The current configuration combining liquid electrolytes with polymer matrices should be more appropriately classified as quasi-solid-state or hybrid systems, rather than true all-solid-state devices. I strongly urge the authors to consult authoritative references on all-solid-state electrolytes to clarify this fundamental distinction. Such terminological inaccuracies risk misleading the electrochemical community regarding device classification standards.\n2. Unsubstantiated \"Memory Effect\" Claim. The authors' persistence in using the term \"memory effect\" remains scientifically untenable. Similar to battery self-discharge mechanisms, this analogy fundamentally contradicts the essential bistable characteristics of electrochromic devices (ECDs). The hallmark of high-performance ECDs lies in their ability to maintain optical states without sustained voltage application - a critical energy-saving feature that distinguishes active electrochromic regulation from passive photochromic/photothermal systems. Although the proposed \"memory effect\" might enable self-regulation in ST-OSC-powered smart windows, it would inevitably undermine the fundamental advantages of standalone OECD and on-chip OECS configurations by causing optical instability during power-off conditions. The authors must either provide comprehensive experimental evidence supporting this unconventional mechanism or remove such speculative claims entirely.\nThis manuscript requires substantial revisions to resolve these fundamental scientific inaccuracies before reconsideration for publication."}, "author_response": "Point-by-point response letter accompanying our Re-Submission of:\nAll-Solid-State Electrochromic Device Enabled by p-n\nComplementary Conductive Polymers: From Self-Powered\nSmart Window to Miniaturized Spectrometer\nManuscript ID: NCOMMS-25-59872B\nDear Reviewers,\nWe thank you for the conscientious peer review of our manuscript and the very helpful\ncriticism. In response to your comments, we have incorporated the suggested changes.\nIn the document below, we comment on all the concerns and points raised. For easy\nreadability we visually structured our response as follows:\nThe comments and points of the referees are copied in black color.\nOur response is colored blue.\nFurthermore, we cite parts from the revised manuscript or the revised Supplementary\nData to afford a quick impression of the improvements and changes made to the text.\nThese citations are indicated by orange text.\nWe hope that we fully answered all the mentioned concerns and issues.\nSincerely,\nFei Huang\nReviewer #4:\n1. Question or issue: Even though the manuscript exhibits a good quality, yet due to\nthe existing issues that I have pointed out, I strongly recommend that the authors revise\nthe term \"all-solid-state\". The concept of all-solid-state electrolytes is currently a\nprominent research focus. However, not all solid electrolytes qualify as truly all-solid-\nstate. Based on solvent content from low to high, they should be clearly classified as\nall-solid-state, quasi-solid-state, and semi-solid-state. While the electrolyte presented\nby the authors exhibits solid characteristics, it does not strictly meet the criteria for All-\nsolid-state. I urge the authors to revise the nomenclature in accordance with rigorous\nstandards. If the authors insist to use this term, since the ionic transference number of\nall-solid-state electrolytes typically approaches one., the authors should provide the\nionic transference number data for this electrolyte. On the other hand, with reference to\nthe standard \"Judgment Method for All-Solid-State Batteries\" (T/CSAE 434-2025), the\ntested sample must first undergo qualitative assessment via visual inspection of\nruptured sections (to confirm no liquid leakage) to exclude apparent liquid residues.\nThis should be followed by quantitative testing involving weight loss after 6 hours of\nvacuum drying at 120°C, with a weight loss percentage (defined as the ratio of mass\nloss to initial mass under specific conditions) of less than 1% to ensure that it can be\nclassified as an all-solid-state battery. The authors are requested to conduct experiments\naccording to this standard and provide TG-DSC data accordingly.\nResponse: We sincerely appreciate the reviewer’s insightful comments regarding the\nclassification of our electrolyte system. In full agreement with the reviewer’s emphasis\non terminological rigor, we wish to clarify that we will not employ the term “all-solid-\nstate” in our manuscript. Instead, we utilize the term “quasi-solid-state gel” to\naccurately reflect the intrinsic nature of the electrolyte. Instead, we have adopted the\nterm \"quasi-solid-state gel\" to accurately reflect the nature of our electrolyte, which\naligns with the solvent-containing classification (all-solid-state, quasi-solid-state, and\nsemi-solid-state) highlighted by the reviewer.\n2. Question or issue: As for my second point, the bistable behavior demonstrated in\nSupplementary Fig. 25 is suboptimal. The authors should explain the self-bleaching\nphenomenon observed in the device and propose potential improvement strategies.\nEnhanced device performance would undoubtedly improve the reliability of the OECS.\nResponse: Thank you for your valuable comment about bistability of the OECD.\nConductive polymers often demonstrate inferior memory effects in electrochromic\napplications due to the metastable nature of their oxidized/reduced states. When the\nHOMO energy level of the polymer in its dedoped state exceeds that of the electrolyte's\nLUMO, thermodynamically driven charge leakage occurs, leading to spontaneous\nelectron back-transfer. To address this challenge and enhance memory effects, we\npropose potential improvement strategies, such as energy level engineering (adjusted\nthe HOMO level of the polymer and selected electrolytes with wide electrochemical\nwindows), kinetic stabilization and device architecture optimization and so on, to\nenhance the memory effect in our further work.\nFinally, we sincerely appreciate the insightful comments and constructive suggestions\nprovided by the reviewers throughout the revision process. The rigorous evaluation not\nonly has significantly improved the quality and rigor of our manuscript, but but also\ndeepened our understanding of the field. Thanks again for the time and expertise\ninvested by the reviewers and editors. Thank the editors for considering our manuscript\nfor publication."}]

Decision letter