Highly oriented semiconducting polymer nanofilm with enhanced crystallinity

Domain: physics
Published: 2025-11-27
Editorial outcome: major_revision

Abstract
Semiconducting polymers are crucial in flexible and wearable intelligent electronic devices. However, their crystallization remains a significant challenge because the crystallization kinetics is limited by the rigid conjugation structure and strong intermolecular π-π stacking. This leads to energetic disorder in electronic structure and poor charge transport, which severely hinders electrical performances of devices. Herein, we report highly oriented semiconducting polymers with enhanced crystallinity prepared by low-temperature plasma-driven evaporation process, during which polymer chains cross the energy barrier and crystallization kinetic for approaching torsion-free conformations. This material possesses an extended intrachain conjugation, ordered interchain stacking, high crystallinity and narrowed density of states contribution, which causes the extraordinary electrical response to stimulations with the emphatic Seebeck coefficient and power factor 1017% and 8295% times those of spin-coated film, respectively.

Introduction
Semiconducting polymers have been extensively explored as candidates in flexible and wearable intelligent electronic devices for their great advantages of low budget, lightweight, and mechanical flexibility1,2. The electrical performances of these devices largely depend on the molecular ordering in the solid state. It is reported that the intrinsically structural disorder in conventional semiconducting polymers from the coiled conformation of polymer chains results in the energetic disorder in electronic structure, forming the Gaussian distribution for the density of states (DOS)3. Therefore, it is tremendously necessary to synthesize the high-crystalline semiconducting polymer to reduce the energetic disorder and optimize their electronic structure4. However, the torsion and entanglement of chains in semiconducting polymers with rigid conjugation backbone and strong π-π stacking interaction create an insurmountable activation energy and kinetic barrier to the rearrangement of chain conformation, leading to a complex free energy landscape with multiple energetic barriers for crystallization5–7. So far, the crystals of semiconducting polymers like polyaniline (PANI), polypyrrole (PPy), and poly(3-alkythiophenes) have been achieved through vapor phase polymerization or solution process methods8,9. However, the controllable fabrication of large-area semiconducting polymers nanofilm with enhanced crystalline structure remains a long-standing challenge, which severely limits the industrial application of semiconducting polymers in the electronic device. Recently, the crystallization of PANI was realized relying on the hydrogen bonding and electrostatic interactions from surfactant monolayer in the interfacial polymerization10–12, while their growth rate was quite slow (~5 nm per day) and the thickness of film was limited under 30 nm. As the thickness became thicker, gradually surpassing the interface, the interactions from surfactant monolayer were weakened, possibly leading to the formation of abundant defects and damaging the crystallization13. Unfortunately, the fundamental thermodynamic and kinetic issues in the crystallization of common semiconducting polymers have not been solved.

Herein, we report highly oriented semiconducting polymers with enhanced crystallinity synthesized by low-temperature plasma stemmed from the modified resonant infrared matrix assisted pulse laser evaporation technique (RIR-MAPLE). By receiving the low-phonon energy of laser, the polymer chains in vapor phase have crossed the energy barriers and crystallization kinetic and been rearranged from their preferred metastable coiled conformation to the stable torsion-free state in the vacuum circumstance. This leads to the deposition of a high-crystalline semiconducting polymer nanofilm with high sensibility and response towards stimulations from light, magnetism and heat.

Results
Design and preparation of highly oriented semiconducting polymers
As illustrated in Fig. 1a, the RIR-MAPLE technique is modified with the adoption of a rotating reflector for the uniform laser ablation, during which a laser ablates a frozen target consisting of solvent and polymer, and the evaporated polymer is deposited on a substrate. Initially, the dispersing agent poly(styrenesulfonate) (PSS) was introduced to form a well-dissolved PANI methanol (with low sticking coefficient) solution for guaranteeing the stretching state of PANI chains (digital photos in Supplementary Fig. 1a), as ascertained by the isotropic wide-angle X-ray scattering (WAXS) pattern in Supplementary Fig. 2. Then the frozen target was instantly attained by liquid nitrogen, in which the PANI chains were immobilized with the stretchable conformation. After being ablated by the laser pulse, the solvent methanol molecules absorbed most of the laser energy, since their O-H stretching vibration bear a resonance enhancement by the laser with the matched wavelength of 1064 nm in the near infrared region, and leave the surface of the frozen target to form the plume. In this situation, the embedded polymers were intactly transferred into the plasma plume because of the collisions between the solvent and polymer as pictured in the digital photos of Supplementary Fig. 3, ultimately stacked on the substrate with the stretching conformation.

During deposition, PSS was designedly removed from the system to avoid them from squeezing into the orderly stacking of PANI chains, damaging the crystalline structure and reducing the moisture stability. According to the density functional theory (DFT) simulation results in Fig. 1b, there is a strong electrostatic attraction between PSS and proton-doped PANI chains, but weak interaction between PSS and de-doped PANI. Hereby, the separation of PSS was obtained by partially de-doping the PANI via the laser-induced plasma14, as detailed described in Supplementary Note 2. Finally, PSS was successfully removed from the system by the strong hydrogen bonding with methanol, justified by the high-resolution X-ray photoelectron spectroscopy (XPS) S 2p spectra in Fig. 1c, d. Subsequently, the deposition of PANI chain was monitored by the atomic force microscope-infrared spectrum (AFM-IR) mode of infrared scanning near-field optical microscopy (SNOM) in Fig. 1e, f and Supplementary Fig. 4. The elaborate deposition stages at different deposition time of 10, 20, 30 and 40 min are emphasized in Supplementary Note 3. It was worth noting that after extending the deposition time over 40 min, the bending chain conformation appeared and caused the accumulative structural disorder, as shown in Supplementary Fig. 5. The nondestructive deposition of PANI chains has been ensured from the minor difference between relative molecular weight of PANI in the nanofilm (75806 Da) and raw material (73186 Da) obtained by the gel permeation chromatograph (GPC) of Supplementary Fig. 6. The chemical structures of PANI including oxidation unit (i.e., quinone ring) and reduction unit (i.e., benzene ring) are well preserved in the nanofilm as examined by the Fourier transform infrared (FTIR) spectra in Supplementary Fig. 7a, Raman spectra in Supplementary Fig. 7b, 1H nuclear magnetic resonance (1H-NMR) spectra15 in Supplementary Fig. 8 and high resolution XPS N 1s spectra in Supplementary Fig. 9, whose characteristic peaks were summarized in Supplementary Table 1 and percentage were calculated in Supplementary Table 2. Within the laser-induced plasma, the PANI chains could go through a rearrangement into the most stable state with alternating ranking of oxidation and reduction units16, as listed in the DFT simulation results in Supplementary Fig. 10a.

Characterizations
Relying on our carefully organized strategy, a uniform, transparent and flexible nanofilm of semiconducting polymers has been produced at deposition time of 10 min and visualized in Fig. 2a. The morphology of the nanofilm shows a homogeneous appearance with an average relative transparency of 92.5% in the visible light region compared to the yellow polyimide (PI) substrate, identified from the ultraviolet-visible (UV-Vis) spectra in Supplementary Fig. 11. The nanofilm signals a uniform morphology with surficial fibrous protrusions in the transmission electron microscopy (TEM) image of Supplementary Fig. 12. This neat PANI layer tightly attaches to the PI substrate, delineating the thickness of 100 nm and the average roughness of 34.5 nm from the scanning electron microscope (SEM) and atomic force microscopy (AFM) images in Supplementary Figs. 13 and 14, respectively.

WAXS pattern indicates the orientation and polymer chain conformation in the nanofilm, which manifests the sharp peaks of strong out-of-plane scattering and relatively weak in-plane scattering. The peaks identified from I(q)~q profiles in Supplementary Fig. 15 deduced from Fig. 2b are summarized in Supplementary Table 3, supporting the edge-on orientations of polymer chains in the nanofilm17. The radius of gyration (Rg) of 17.01 Å and fractal dimension (Ds) of 2.01 calculated from Fig. 2b in Supplementary Table 4 clarify the elongated Gaussian chain state upon the nanofilm18, comparable to the chain conformation in the methanol solution with a Rg of 9.88 Å and Ds of 1.22 obtained from Supplementary Fig. 2. The grazing incidence X-ray diffraction (GIXRD) pattern in Fig. 2c displays the relatively sharp reflection intensity. Combined with TEM investigations (vide post), the structure exhibits an orthorhombic unit cell with lattice parameter of a = 5.35 Å and b = 9.99 Å. Nevertheless, a large c axis along the polymer chain axis is determined, as corroborated by the low-angle XRD result under transmission mode, as presented in Supplementary Fig. 16d, in which a broad intensity distribution in the 2θ region of 1.74–2.19° indicates that the c axis varies from 40.28 to 50.74 Å. The characteristic peaks of PANI with emeraldine salt (ES) state is summarized in Supplementary Table 5. In term of the equation in Supplementary Note 1, the crystallinity of polymers in nanofilm is estimated to be 89.3%. GIXRD pattern is also exploited to derive the grain size (L) and interchain separation length (R), and the results are summarized in Supplementary Table 6. Generally, a larger L value benefits the intrachain charge carriers transport along with the conjugate backbone and a lower R value improves the probability of interchain hopping of charge carriers19,20. In Supplementary Table 6, the intrachain transport of charge carriers is ameliorated in our nanofilm with the L value of 81.0 nm relative to that of 41.2 nm for the spin-coated film, conforming the increasing conjugation length of polymer chain. By contrast, the R value in our nanofilm with a value of 5.8 nm shows a slight difference relative to that of 5.4 nm for the spin-coated film.

In order to further confirm the crystalline structure, the PANI nanofilm was peeled off from the substrate, and data were collected employing the three-dimensional electron diffraction (3D-ED) technique. Figure 2d–f show the projection of the reconstructed 3D reciprocal lattice from c*, b* and a* axes of PANI nanofilm, respectively. The 3D-ED data show discrete diffraction spots consistent with single crystal diffraction, while the diffraction intensity and the fluctuation in their position may be from the uneven length of polymer chain segments along the polymer chain direction (c-axis), that possibly cause the dislocation and defect in the crystal of polymer as well as formation of amorphous phase. Particularly, the hk0 reflections are well ordered, while the 00l reflections tend to be positionally deviated and have a more diffuse intensity distribution, indicating that the PANI chain is well arranged in the ab plane but shows less ordering in the long-axis of polymer chain (c-axis). Although the diffuse diffraction intensity and positional shifts along the c*-axis pose challenges in determining the extinction rules, the typical reflection conditions of {hkl: h+k=2n}, {hk0: h+k=2n}, {h00: h=2n} and {0k0: k=2n} suggest a potential C-centered orthorhombic lattice. The unit cell parameters of a = 5.3 Å, b = 10.0 Å and c = 45.2 Å are determined, which align well with the XRD results (Fig. 2c and Supplementary Fig. 16d). However, the obtained 3D-ED data are not sufficient to resolve the structure in molecular level due to the imperfections in the crystallization of polymer chains and the presence of structural fluctuations. Therefore, we further analyzed the structure through high-resolution TEM (HRTEM) imaging. The representative HRTEM image with the corresponding selected area electron diffraction (SAED) pattern taken from the c-axis is shown in Fig. 2g, showing mm symmetry with centered structure as suggested from the extinction conditions. The unit cell parameters calculated from the SAED pattern a = 5.3 Å and b = 10.0 Å, which are consistent with the XRD and 3D-ED results. The average structural information was obtained from Fourier transformation of the HRTEM image (Fig. 2g) using the crystallographic image processing software CRISP21, suggesting the plane group symmetry of c2mm (Fig. 2h). The black contrast indicates the areas with high electrostatic potential density, corresponding to the positions of the polymer chain. Since the arrangement of polymer chains is not as ordered as that of atomic crystals, we can only observe the overall electrostatic potential density distribution considering each polymer chain as a whole. Based on the averaged projected potential, the C2mm (No. 38) is suggested to be the most possible space group symmetry. However, to establish the structural model, we utilized P1 symmetry and then the chain configurations were optimized by using the DFT method in the Vienna ab initio simulation package (VASP) for energy minimization. As shown in Fig. 2i, the growing direction of PANI nanofilm is along the substrate, and it is stagger-stacked in the form of a C-centered orthorhombic structure. While the packing of polymer chain is more random in the direction of chain extension. In this structure, the interchain distance from 3.8 to 4.2 Å suggests the strong π-π stacking and implies the edge-on orientation of PANI chain with the benzene ring perpendicular to the substrate, which is also confirmed by WAXS results22. The simulated SAED, XRD and 3D-ED profiles derived from the structural model shown in Supplementary Fig. 16a–d and Supplementary Movie 1 display concordance with aforementioned experimental results, which proves the reliability of this model. In addition, large-scale TEM image and corresponding SAED patterns taken from large area of the film in Supplementary Fig. 16e demonstrate a consistent and uniform structure with single-crystalline characteristic within the nanofilm with clear lattice fringes and discrete diffraction spots. Crystalline grains with blue fluorescence response were also observed in the nanofilm through fluorescence microscope images as shown in Supplementary Fig. 16f. By contrast, the film prepared from the common spin-coating method only discloses a crystallinity of 45.5%, whose results are listed in Supplementary Note 4.

Electronic structure and electrical transport properties
By managing the chain conformation, orientation, and crystallinity in semiconducting polymer, its energetic disorder has been cut down to a degree. The electronic structure of the polymer in nanofilm was measured from the superconducting quantum interference device (SQUID) magnetometry and ultraviolet photoelectron spectroscopy (UPS). The SQUID magnetometry was employed to conduct the temperature-dependent magnetic susceptibility data (χ~T) in Fig. 3a. The PANI nanofilm uncovers a weak temperature-dependent paramagnetic property in the temperature range of 100–300 K, where Pauli paramagnetic susceptibility (χP) and the DOS at the Fermi level (N(EF)) have been acquired from the linear χT~T plot as inset of Fig. 3a23. As described above, the DOS of semiconducting polymers normally follows the Gaussian distribution centered at the Fermi level. Our nanofilm gains a much higher N(EF) of 2.72 × 1023 state eV−1 m−3, compared with that of 9.28 × 1021 state eV−1 m−3 for the spin-coated film, which implies the narrowed DOS distribution of our nanofilm. Besides, the electronic structure of nanofilm also brings about unique fluorescence emission around 500 nm (2.48 eV) under the excitation wavelength of 325 nm (3.81 eV), which is unseen in the spin-coated film, as illustrated in the right of Fig. 3b. This might be due to the narrower bandgap of 1.82 eV in nanofilm compared with that of 1.95 eV in spin-coated film, calculated from UV-Vis spectra in left of Fig. 3b and listed in Supplementary Table 7. The N(EF) of the PANI nanofilm is also sensitive to the magnetic field, as listed in Supplementary Table 8, which is increased from 5.69 × 1023 to 2.30 × 1024 state eV−1 m−3 when magnetic field B reaches 3 T, which means that the DOS distribution in nanofilm becomes narrower under the magnetic field. For comparison, the N(EF) of spin-coated film only exhibits a slight increase from 1.38 × 1022 to 2.75 × 1022 state eV−1 m−3 in the same condition. From the UPS spectra in Supplementary Fig. 17, the work function (Φ) has been computed and listed in Supplementary Table 9. The lower Φ of 6.45 eV in nanofilm, relative to 7.76 eV of the spin-coated film, makes a better interface matching with the metal electrodes due to the declined potential barrier, which promotes the charge carrier transport and electrical performance within the electronic device based on our nanofilm, see details in Supplementary Note 6-(2). Moreover, the values of the N(EF) and Φ in Fig. 3c express an obvious size-dependency toward the thickness of nanofilm. This denotes that the electronic structure of nanofilm could be easily regulated by its thickness, i.e., deposition time. It is noticed that with extending deposition time, the structural disorder is accumulated in the nanofilm from the formed several deep channels by ablating the frozen target of laser as illustrated in Supplementary Fig. 18. To solve this issue, our modified MAPLE still needs to be upgraded in the future.

The excellent physical structure and electronic structures accelerate the charge carrier transport within the PANI nanofilm. The temperature-dependent electrical conductivity (σ~T) is determined in the inset of Fig. 3d, from which the reduced activation energy (W) has been derived24. In line with the temperature-independent W~T plot in Fig. 3e, our nanofilm lies in the critical regime of metal-insulator transition below 200 K. In this condition25, the σ~T curve follows the power law of σ(T) ∝ Tβ with β value of 0.49. At temperature over 200 K, W~T plot with positive slope implies that the PANI nanofilm crosses from the critical regime to the metallic regime, illustrating the metallic transport behavior of nanofilm. The dominant contribution of Pauli paramagnetism possessed from the χT~T plot in Supplementary Table 10 expresses the delocalized nature of charge carriers in our nanofilm, which manifests the metallic coherent charge transport as well. This behavior recommends the unique quantum effect in the nanofilm, since the spin-coated film prefers the insulator regime originated from the negative slope of W~T plot in Supplementary Fig. 19f. Moreover, since our nanofilms still exhibit the characteristics of imperfect crystallization of the polymer chain as confirmed by 3D-ED data above, Mott variable range hopping (VRH) theory (see Supplementary Note 1) is adopted to process the σ~T data and explore the mechanism of charge transport in the semiconducting polymer film. Our nanofilm (Fig. 3d) displays a fitting parameter of x=3 (Supplementary Table 11), designating a quasi-2D Mott VRH mechanism for the charge carrier transport behavior. For comparison, a 3D VRH mechanism (x=4) is noticed in the spin-coated film from Supplementary Fig. 19e. Testing under the four-probe method, our nanofilm holds an electrical conductivity up to 1.71 S cm−1. The charge carrier density of our nanofilm is worked out to be 4.01 × 1017 cm−3 and the room temperature Hall mobility reaches 0.75 cm2 V−1 s−1 by Hall effect measurement, as demonstrated in Fig. 3f and Supplementary Table 12. Clear Hall signal is transcribed in a wide temperature range from 298 to 343 K and the positive slope for the linear plot of VH/I~B coincides to the p-type doping.

The metallic coherent charge transport is also consistent with the negative magnetoresistance (MR) phenomenon in a wide temperature range with increasing absolute value of MR as the temperature decreases, as exhibited in Fig. 3g. This phenomenon could be explained through the weak localization effect, which arises from the coherent backscattering when a constructive interference happens between charge waves opposite transferring along closed paths with equal probabilities26. The magnetic field would break this balance and reduce the backscattering, further enhancing the electrical conductivity27. The MR data have been processed by the simplified Hikami–Larkin–Nagaoka model from the weak spin-orbit coupling assumption, see details in Supplementary Note 1, where the inelastic scattering time (τφ) and length (λφ) are received and recorded in Fig. 3h. The larger τφ and λφ could be found at low temperatures, which intimates the increased degree of charge coherence and agrees with the rising MR value28. Furthermore, the temperature-dependent τφ against T−2 depicts clearly that the electron-electron scattering acts as a dominant scattering mechanism29. Successively, in-situ Kelvin probe force microscope (KPFM) has been carried out under magnetic field for scanning the surface potentials of our nanofilm, as arranged in Supplementary Fig. 20 and Supplementary Movie 2. With B increasing to 75 mT, the surface potential of nanofilm is gradually decreased without obviously surface morphology altering in Supplementary Fig. 20. The estimated surficial Φ of our nanofilm evinces a downtrend in Fig. 3i, signifying the boosted charge carrier transport under the magnetic field, which testifies to the occurrence of spin current in the PANI nanofilm under magnetic field30.

The MR property also affirms the conversion of charge carriers between polaron and bipolaron in accordance with the bipolaron theory31,32. Spinless bipolaron is ascertained to be the major charge carrier in the nanofilm, since its electron paramagnetic resonance (EPR) spectrum in inset of Fig. 3i barely exhibits signal. For comparison, the strong intensity in EPR spectrum of spin-coated film hints the dominance of polaron. The localization length (a0) derived from MR data in Supplementary Table 8 is also coincided with the conjugation of polymer chain and formation of bipolaron in the PANI nanofilm, since its a0 of 83.0 nm is much larger than that of spin-coated film (13.2 nm).

Applications and stability
The single-crystalline structure and metallic coherence charge transport have brought our semiconducting polymeric nanofilm great potential in applications within the electronic nanodevices. Primarily, the sensor properties towards magnetic or optical signal are discussed. Under the B of 3 T, the room-temperature negative MR with a value of −3.2% was detected in the nanofilm, while a more usual positive MR phenomenon with a value of 1.8% was discerned for the spin-coated film under the same condition (Supplementary Fig. 21a). It is also noted that the nanofilm also gains high MR sensitivity of 3.38% T−1 under low magnetic field, nine times higher than that of spin-coated film (0.37% T−1), as shown in Fig. 4a. The photoconductivity was also assessed under the Xenon lamp, as explicated in Fig. 4b and Supplementary Fig. 21b, c. The PANI nanofilm exhibits a stable signal during 100 on/off cycles and the highest on/off ratio of 2.59, which is 1.8 times of that for spin-coated film (1.44).

The thermoelectric performance of the PANI nanofilm was also evaluated. Our nanofilm reveals an excellent thermoelectric capability with the highest power factor (PF) up to 9328.2 μW m−1 K−2 due to a high Seebeck coefficient of 8544.0 μV K−1. By contrast, the PF for spin-coated film only reaches 103.1 μW m−1 K−2 since its Seebeck coefficient is 840.2 μV K−1. It is obvious that the PF and Seebeack coefficient of our nanofilm are 83.0 and 10.2 times those of the spin-coated film, respectively. The thermoelectric voltage output of the PANI nanofilm is also stable among a wide temperature range, as mentioned in Supplementary Fig. 21d. Our nanofilm shows very high thermoelectric performance in comparison with published works, as listed in Supplementary Table 13. The much higher N(EF) and increasing bipolaron in our nanofilm relative to spin-coated film denotes the narrow DOS shape, enhanced DOS slope at EF and increased asymmetry33, according to the inset of Fig. 4c. From the positive correlation between the N(EF) and effective mass of charge carrier (m*) in Supplementary Note 1, the ratio of m* between the nanofilm and spin-coated film is calculated to be 10.9, close to the ratio of their Seebeck coefficient of 10.2. Referring to the correlation of PF~N(EF) in Fig. 4c, it is declared that the growth of the N(EF) in our nanofilm leads to the larger m*, further raising the Seebeck coefficient. The enlargement of m* could be fundamentally originated from the strengthened electron-photon coupling interaction by the formation of aforementioned bipolaron in the semiconducting polymer34.

Furthermore, an interesting positive magneto-thermoelectric (MTE) phenomenon was discovered in our nanofilm. The voltage output of thermoelectric device demonstrates a step-up tendency in Supplementary Fig. 21e under the rising magnetic field strength. Eventually, the Seebeck coefficient increases to 8860.2 μV K−1, and the PF value achieves 10213.2 μW m−1 K−2 under B of 680 mT, as explained in Supplementary Table 14. This may be the reason that on one hand, the negative MR brings the rising of electrical conductivity under the magnetic field. On the other hand, the enlarged m* derived from the magnified N(EF) under magnetic field in Supplementary Table 8 leads to the promotion of Seebeck coefficient35. This brings the decoupling and simultaneous amelioration of electrical conductivity and Seebeck coefficient under magnetic field, as illustrated in Fig. 4d.

Our PANI nanofilm owns a superb moisture stability resulting from the designed removal of PSS, which prevents the moisture-derived degradation of electronic device36. As revealed in Supplementary Fig. 22a, the PANI nanofilm exhibits the electrical conductivity and Seebeck coefficient with minor difference during a 30-day period when being packaged into a thermoelectric device, characterized as Supplementary Fig. 22b. After being immersed in water for one week, the surface of our nanofilm displays no obvious damage and the microstructure observed by SEM is still tidy in Supplementary Fig. 23. Based on the exceptional moisture stability, a water-assisted transfer printing becomes possible by depositing PANI nanofilm upon a soluble substrate (e.g., KBr panel) as drawn in Fig. 4e and Supplementary Fig. 22c. The whole PANI nanofilm is quickly peeled off when the substrate is disintegrated in water. Then, the free-standing nanofilm could be completely re-printed upon an untreated PET substrate, maintaining its transparency. This feature makes convenience for the coating of semiconducting polymer nanofilm upon irregular substrate37.

Generality
The generality of our strategy is proved in different semiconducting polymers like polypyrrole. Since the PSS was removed during the RIR-MAPLE process, as proved by XPS in Supplementary Fig. 24, the PPy nanofilm exposes a good crystalline structure as well with a large-scale crystallographic lattice fringe in HRTEM image of Supplementary Fig. 25. In a word, our strategy could manipulate the chain conformation and crystalline structure in semiconducting polymers.

Methods
Materials
Aniline (C6H7N, ≥99.5%) and ammonium persulfate (APS, ≥98.0%) were purchased from Aladdin Reagent (Shanghai) Co., Ltd. Poly(sodium-p-styrenesulfonate) (PSS, Mw=70000) was obtained from Shanghai Macklin Biochemical Co., Ltd. Sulfuric acid (95.0–98.0%), ammonia (25.0–28.0%), acetone ≥99.5%) and methanol (≥99.5%) were supplied by Sinopharm Chemical Reagents Co., Ltd. All chemicals were used as-received without any pre-treatment.

Synthesis of polyaniline
Aniline was added into sulfuric acid solution with an aniline to sulfate mole ratio of 1:2.5 under sonication until the formed salt was well dissolved. PSS was dispersed in deionized water with an aniline to PSS mass ratio of 0.9:1 under mechanical stirring (300 rpm) for 1 h. Two solutions above were mixed firstly, followed by the addition of APS solution with an aniline to APS mole ratio of 1:1. Reaction system was kept in an ice-water bath with continuous mechanical stirring and sonication for 2 h. Lastly, acetone of equal volume was added into the reaction system and the product was filtrated and dried to obtain soluble PANI/PSS (PANI bulk). Insoluble polyaniline (PANI) was also manufactured with the same procedure without addition of PSS.

Fabrication of polyaniline nanofilm by RIR-MAPLE process
The target solution (2 wt%) was prepared by dissolving PANI bulk in methanol under sonication. About 5 mL of solution was loaded in the target cup in the nitrogen atmosphere, which was then rapidly cooled in liquid nitrogen until the solution was completely frozen at about −120 °C. The polyimide substrate (PI, thickness of 25 μm) was attached to a holder. The target cup was installed inside the RIR-MAPLE chamber with a target-to-substrate distance of 3 cm. The chamber was then quickly evacuated using a pump (TRP-24, Beijing Beiyi Woosung Vacuum Technology Co., Ltd) and the vacuum degree was maintained at a magnitude of 10−1 Pa during the deposition process. The Nd:YAG laser (Quanta-Ray Lab, λ=1064 nm, Spectra-Physics) was set with an energy density of 294 mJ per pulse and focused on a tiny spot upon the target through a clockwise rotating reflector (6 rad min−1). Throughout deposition, the target was kept at a temperature range around −150 to −170 °C, monitored by a thermocouple, and the substrate was kept at 50 °C by heating with a laser radiation (λ=808 nm, FC-W-808-50W, Changchun New Industries Optoelectronics Tech Co., Ltd). The deposition was carried out for 30 min and the obtained film was called Untreated PANI nanofilm. After that, the Untreated PANI nanofilm was annealed at 150 °C for 12 h in the nitrogen atmosphere with a gas flow rate of 20 mL min−1 by using a tube furnace. The attained film was indexed as Annealed PANI nanofilm. Finally, Annealed PANI nanofilm was immersed in the 20 mL of sulfuric acid (1 M) with 3 h for the secondary doping process and taken out for drying. This sample was named as NF-30. For comparison, the different deposition times for 10, 20, and 40 min were also performed with the same procedure and the samples were labeled as NF-10, NF-20, and NF-40 min, respectively.

Characterizations
The microstructures and morphologies of PANI nanofilm were observed by a field emission scanning electron microscope (SEM, Hitachi S-4800), high-resolution transmission electron microscopy (HRTEM, FEI Tecnai G2-F30 and JEOL JEM-F200) and atomic force microscope (AFM, Bruker Dimension Icon). During TEM testing, the 3D electron diffraction (3D-ED) data were collected at a low dose mode at 298 K on a Synergy-ED and equipped with a HyPix-ED electron detector under 200 kV. For the PANI nanofilm, 244 ED patterns were collected with the tilting angle ranging from −55° to 60°. Each frame was collected with an exposure time of 0.750 s, resulting in a 0.43° wedge per frame. The 3D reciprocal space was reconstructed using the program CrystalAlisPro for ED. Surface phases were analyzed by infrared scanning near-field optical microscopy (SNOM, Bruker NanoIR3-s) in the AFM-IR mode at a wavenumber of 1308 cm−1 that is representative for the C-N stretching vibration of benzenoid in PANI. The grazing incidence X-ray diffraction (GIXRD) patterns were identified through X-ray diffractometer (Bruker D8 Advance) with Cu Kα1 (hν= 8.05 keV) radiation. Wide angle X-ray scattering (WAXS) patterns were tested by Xenocs Xeuss 3.0 beamline with Cu Kα1 radiation in grazing incidence mode. X-ray photoelectron spectroscopy (XPS) was recorded on a Thermo escalab 250Xi spectrometer respectively with Al Kα (hν= 1486.6 eV) radiation. Ultraviolet photoelectron spectroscopy (UPS) was recorded on a Thermo ESCALAB 250Xi spectrometer, respectively with He I (hν= 21.20 eV) radiation. Thermal properties of samples are analyzed by a thermogravimetric analyzer (TGA, TA Instruments, TGA 55) and differential scanning calorimeter (DSC, TA Instruments, DSC 25). Fourier transform infrared spectroscopy (FTIR) was analyzed by an infrared spectrometer (Thermo Nicolet NEXUS) and ultraviolet-visible spectroscopy (UV-Vis) was carried out with an ultraviolet-visible-near infrared spectrometer (Agilent Technologies, Carry 5000). Fluorescence spectrum (FL) was collected by fluorescence spectrometer (Hitachi F-7000). The Raman spectroscopy was carried out with a Raman spectrometer (Invia 514 nm, Renishaw Inc.). The molecular weight of polymer was evaluated with gel permeation chromatograph (GPC, Shimadzu GPC-20A) and the PANI in nanofilm was dissolved by dimethyl sulfoxide (DMSO). 1H Nuclear magnetic resonance (1H-NMR) spectra were recorded by Bruker AVANVVE III (400 MHz) using DMSO-d6 as solvent. Temperature-dependent magnetic susceptibility was carried out on a superconducting quantum interference device (SQUID, MPMS SQUID XL5, Quantum Design). The electron paramagnetic resonance (EPR) spectroscopy was recorded by Bruker A300-10/12. Morphology and surface potential of PANI nanofilm under an external magnetic field (B) were detected by using Kelvin probe force microscope (KPFM, Bruker Dimension Icon) with a HQ:NSC18/Pt tip, whose work function was confirmed as 4.33 eV referring to a highly oriented pyrolytic graphite (4.60 eV).

Electrical performance measurements
Electrical conductivity of PANI nanofilm was tested with a digital source meter (Keithley 2400) through the four-point probe method. To assemble a thermoelectric device, PANI nanofilm was cut into size of 2.5 × 1.5 cm and packaged with two Pt electrodes by the plastic envelop machine. The heat side of device was attached to the outside wall of a copper tank containing continuously heated water and cold side was exposed to the air. The temperature difference (ΔT) was monitored by a thermocouple. The output voltage (ΔV) under different ΔT was recorded using an electrostatic meter/high resistance meter (Keithley 6517B) by changing the temperature of the heat side from 20 to 60 °C. The Seebeck coefficient was obtained from the linear fitting of ΔT~ΔV plot. The thermoelectric results were also examined using Seebeck coefficient measurement system (Advance Riko ZEM-3M8). For MTE test, the aforementioned testing procedure of thermoelectric performance was carried out in a custom-made electromagnet, with thermoelectric device perpendicular to the magnetic field. Photoconductivity performance was measured by putting the packaged nanofilm under the illumination from a Xenon lamp (BBZM-1), whose full power was 470 W and full illuminance was 5800 lx. The output current of device was recorded using a digital source meter (Keithley 2400) with input voltage of 5 V. Temperature-dependent resistivity, Hall effect and MR tests were performed with a physical property measurements system (Quantum Design PPMS-9T (EC-II)) at different temperatures. Please see detailed temperature in the results of Fig. 3d, f, g, respectively. The MR performance of nanofilm was tested under a step-wise raised magnetic field with a step length of 80 mT.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "As suggested by their title, the major claim of the authors of this manuscript is that they have fabricated single-crystalline semiconducting polymer. There are two pieces of data that support their claim: discrete spots in selected area electron diffraction (SAED) and high degree of crystallinity calculated from x-ray scattering. The author have also employed a gamut of techniques to characterize their films. The authors report an extremely high power factor (~9300 microW/m/K^2), which is probably one of highest reported power factors for an organic system. Typically they are around the 3000 microW/m/K^2 range.\nGiven below are my comments:\n1. The title is misleading. They seem to have crystalline-domains of ~80 nm in size (SI Table 6). PANI with such crystalline domains with discrete spots in SAED have been reported (1. Zhang, T. et al. Engineering crystalline quasi-two-dimensional polyaniline thin film with enhanced electrical and chemiresistive sensing performances. Nat Commun 10, 4225 (2019).; 1. Gao, Y., Kang, Z.-H., Li, X., Cui, X.-J. & Gong, J. Vapour phase synthesis of crystalline polyaniline with dendritic morphology. CrystEngComm 13, 3370–3372 (2011).1. B. Puthirath, A., Methattel Raman, S., Varma, S. J. & S, J. Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach. Applied Physics Letters 108, 161901 (2016).). Such crystalline patterns have also been observed for polymers like P3HT (1. Kayunkid, N., Uttiya, S. & Brinkmann, M. Structural Model of Regioregular Poly(3-hexylthiophene) Obtained by Electron Diffraction Analysis. Macromolecules 43, 4961–4967 (2010).) Therefore the authors may want to present their work in the context of these literature precedence.\n2. The authors cite Nat. Communication 2019 paper (Ref 12) but indicate that there are abundant defects\" \"whereas abundant defects were built when the polymerization gradually surpassed the interface\".(Ref 12)\nYet, a careful read of that paper indicates a low defect density was achieved in PANI films in Ref 12. The authors of that paper clearly state that \"the misorientation between adjacent PANI domains is typically below 15° (Supplementary Fig. 8), implying low defect density in the q2D PANI thin film\". Thus, the authors of this manuscript should carefully compare their data with that manuscript and present the differences.\n3. The authors claim a crystallinity of 89.3% and refer to SI note 1. Yet the note does not provide details about how the scattering data was treated. What was used to model the amorphous phase? How was incoherent scattering treated? Was it removed? The authors may want to check this reference for appropriate treatment (Shen, X., Hu, W. & Russell, T. P. Measuring the Degree of Crystallinity in Semicrystalline Regioregular Poly(3-hexylthiophene). Macromolecules 49, 4501–4509 (2016).)\n4. In the SI Table 7, the UV band gap. It seems that the deposition times matter. After 10 min, the film band gaps approach spin-coated films. I assume that longer deposition times lead to thicker films. This data would indicate that crystallinity is not maintained as the deposition time gets longer. Can the authors provide an explanation as to why the band gap goes up again? Are they not crystalline? One would have expected that a truly crystalline film would template crystallinity.\n5. On line 195, the author correlate work function to charge transport. What is the basis for this statement?\n6. The authors report the use of VRH theory to model conductivity data. This theory is often used for disordered semiconductors with hopping conduction. Is the conduction mechanism still assumed to be hopping in these systems? Is the implication that the conduction will still be hopping in crystalline domains? Any insights would be helpful to the reader.\n7. SI table 13 misses some of the high numbers for Power factors. See also 1. Cho, C. et al. Outstanding Low Temperature Thermoelectric Power Factor from Completely Organic Thin Films Enabled by Multidimensional Conjugated Nanomaterials. Advanced Energy Materials 6, 1502168 (2016).\n2. Cho, C. et al. Organic thermoelectric thin films with large p-type and n-type power factor. J Mater Sci 56, 4291–4304 (2021).\n8. In SI Table 12, the authors report charge carrier mobility as a function of temperature. The mobility seems to drop from 0.75 to 0.60 cm2/V/s as they change the temp from 298 to 343 K. The charge carrier density does increase slightly. As a result the conductivity drops as a function of temp. This is interpreted as metal-like transport. Have the authors ruled out changes to the film morphology as the temperature increases that causes the mobility to be lower?", "reviewer_2": "In this work, the authors developed semiconducting polymers with single-crystalline characteristic prepared by low-temperature plasma-driven evaporation process, which possesses an extended intrachain conjugation, ordered interchain stacking, high crystallinity and narrowed density of states contribution. The result of this work is interesting, and I believe it is worthy of publication in Nature Communications. I only have some minor comments on the manuscript: In Fig.1d, why S is remained for de-doped PANI nanofilm after removal of PSS? What is the thickness of PANI nanofilm?", "reviewer_3": "The manuscript “ Single-crystalline semi-conducting polymers” prepared PANI films using RIR-MAPLE and performed various characterizations. It is obvious that PANI films have high crystallinity, but it is difficult to find clear evidence that it is a single crystalline PANI films. In addition, the overall presentation suffers from a lack of clarity and coherence. The manuscript is difficult to follow due to ambiguous wording and poor organization of the experimental results and discussion. These issues make readers difficult to understand the motivation, methodology, and scientific contributions of the work. Substantial restructuring would be necessary to make the work accessible and interpretable to the broader scientific community. The detailed comments are attached below.\n-In introduction, previous effort and results about high crystalline conducting polymer films should be presented. In the current version, there is no related previous research introduced, which make it difficult to evaluate the progress of this manuscript.\n-The author reported that the crystallinity for the poly(3-alkylthiophenes)- Why is the technique used in Ref[8] not applicable for PANI and polypyrole? The author mentions that there is a thermodynamic and kinetic and thermodynamic issues (Page 1, Line 23). This should be clearly explained and compared.\n-To prove single crystallinity, GIXRD was carried out. However, this is more suitable for surface characterization. Single-Crystal X-ray Diffraction (SCXRD) and Polarized Optical Microscopy (POM) should be performed to characterize single crystallinity.\n-Experimental steps are not clearly stated. For instance, how PSS was removed? Was it characterized? How molecular weight of PANI in the nanofilm was measured? How radius of gyration was measured?\n-What makes PANI gets transferred through methanol – but not PSS? How could author conclude there is no PSS? What makes PSS have strong attraction with proton doped PANI chains not with de-doped PANI? What in AFM-IR makes the author conclude the absence of PSS?\n-The authors report photoconductivity (on/off = 2.59), seebeck coefficient (8544 uV/K) , power factor (9328 μW/mK2), magneto-thermoelectric response. The experimental procedure should be provided. For example, what is the temperature range of the thermoelectric test? The voltage response with respect to various temperature should be tested.\n-The supporting materials are quite comprehensive, however it suffer from lack of connection with the main text. A guideline for the reader to follow the supplementary text and figures would be helpful.\n-The author generalizes it with polypyrrole. The authors also should report the values of Seebeck coefficient, magnetoresistance, power factor and other applicable attributes? Also, Could the author visualize the density of states in spin coated polypyrole and crystalline polypyrole?\n-Explanation on why extending deposition time over 40 could lead to accumulative structural disorder could be added to enhance clarity.\n-Could the authors discuss whether the crystallinity or molecular ordering of the PANI nanofilm plays a role in magnetic sensitivity? Specifically, how might the degree of structural order influence the modulation of electronic states under magnetic fields?\n-Authors mentioned that “Testing under the four-probe method, our nanofilm holds an electrical conductivity up to 1.71 S cm-1”, how is the conductivity comparing with bulk or spin coated film? Higher crystallinity generally leads to higher conductivity due to enhanced molecular order and carrier mobility.\n-In its current state, the manuscript does not meet the scientific standard required for publication in a high-impact journal. I therefore recommend rejection."}, "author_response": "Response: Thank you for the reviewer’s suggestion. The crystalline domain in Table S6 is calculated from the XRD pattern by the Scherrer equation, which stands for the average thickness of grains perpendicular to the crystal plane direction rather than the aera of crystalline domain. It is reasonable that our nanofilm with thickness of ~190 nm shows grain thickness of ~80 nm. We have changed the name of this value into Scherrer grain size to avoid misunderstanding. Please see yellow highlight in Lines 12-14 of Page S1 and Supplementary Table S6 in the Supporting Information. Actually, the crystalline domain size of our nanofilm is observe to be larger than 500 nm by TEM (Please see Fig. S66). We have carefully read all the references provided by reviewer which is very helpful to improve our future works. We still believe that our work is distinguished among them. The detailed analysis is listed by points. (1) Nat Commun 10, 4225 (2019). This article is mentioned for the second time in Question 2. We have made a comprehensive comparison between this work and our work in the response to Question 2. (2) CrystEngComm 13, 3370–3372 (2011). In this article, the authors reported the dendritic crystal of PANI and analysis the lattice parameter of the crystal. Their conclusion on crystalline cell of PANI is reference valuable, while our materials are not comparable, since what we provide is a large-scaled nanofilm with single-crystalline characteristics rather than nano-scaled single crystal. (3) Applied Physics Letters 108, 161901 (2016). In this article, the authors used solution casting method to provide PANI film with crystallinity of 78.81%. This method is too crude and uncontrollable, so that their films display the thickness in a wide range of 0.5–1.5 μm. In addition, the crystalline structure of their film is only proved by XRD without other evidences. In our work, we realize the single-crystalline characteristic in PANI nanofilm, which is confirmed by GIXRD, GIWAXS, TEM, SAED and 3D-ED. The thickness of our nanofilm could be easily controlled during the MAPLE process. It is obvious that our preparation method for PANI nanofilm is more accurate and controllable, and the conclusion on the crystalline structure is more reliable. (4) Macromolecules 43, 4961–4967 (2010). In this article, the authors analyzed the crystalline structure of P3HT mainly using the electron diffraction. However, their electron diffraction pattern is more similar to polycrystalline rings, absolutely different from the orderly single crystal lattice in the SAED pattern of our nanofilm. In addition, the high crystallinity of P3HT is achieved by the parallel arrangement of its side-chains, which stabilize the π-π stacking of the main chain and regulate the crystallization kinetics. This mechanism is not suitable for general semiconducting polymer without specialized functional group (i.e. long alkyl side-chains in P3HT). On the contrary, our method shows generality in semiconducting polymer with different chemical structures including PANI and PPy.\nIn addition, as the reviewer indicates that the title is misleading. After carefully evaluation, we have decided to change the title to “Semiconducting polymers with single-crystalline characteristic”. Please see changed title.\nResponse: Thank you for the reviewer’s suggestion. Ref. 12 reported a method to synthesize PANI film at the air-water interface with the assistance of a surfactant monolayer. Their PANI film had a large size (~50 cm2) and low defect density, as the reviewer mentioned. However, the growth rate of their method was quite slow (~5 nm per day) and the thickness of film was limited under 30 nm (Please see Fig. 4 of Ref. 12). They didn’t provide the results of thicker film. In their method, the self-assembly of PANI was ruled by the hydrogen bonding and electrostatic interactions from surfactant monolayer. As the thickness became thicker, gradually surpassing the interface, the interactions from surfactant monolayer were weakened, possibly leading to the formation of abundant defects and damaging the crystallization. This might be the reason why the thickness of their film was limited under 30 nm. Besides, Ref. 12 did not display more electrical performances either, except for gas sensor, in their film with such good structure. With our method based-on MAPLE technique, we can realize a single-crystalline characteristic in PANI nanofilm with size over 50 cm2 with high deposition efficiency (~8 nm min-1). The thickness of nanofilm could be varied from 10 nm to ~1 m by simply controlling the deposition time. Thanks to its unique structure, our nanofilm gains excellent and abundant electrical performances including thermoelectric, magnetoresistance and photoconductivity. Comparatively speaking, our method has the potential for the industrial manufacture of semiconducting polymer film with excellent crystalline structure and electrical properties. We have modified the statement on Ref. 12 to avoid misunderstanding. Please see yellow highlight in Lines 1-6 of Page 2 in our Manuscript.\nResponse: Thank you for the reviewer’s comments. In fact, the crystallinity in this work was approximatively calculated from the GIXRD pattern and the background arising from incoherent scattering has been subtracted during the testing. The GIXRD pattern has been divided into amorphous and crystalline constituents, and crystallinity is defined as the aera percentage of crystalline peaks. The location of peaks is conformed according to the d-spacing from other characterizations including HRTEM, SAED and 3D-ED, and the FWHM of peak is optimized to gain a best fitting. The peaks with FWHM>3.0 are regarded as amorphous phase according to the method in Ref. 3 in the Supporting Information. We have added the details in Supplementary Note 1-(2). Please see yellow highlight in Lines 11-12 and 17-22 of Page S1 in Supporting Information. We have carefully read this reference and cited it in our work. Please see Ref. 2 in the Supporting Information. It is very helpful for improving our work.\nResponse: Thank you for the reviewer’s comments. The extension of deposition time does raise the thickness of film and leads to the lower crystallinity and larger band gap. Please see Tables S6 and S7 in Supporting Information. The reason might be that, after extending the deposition time, the frozen target in MAPLE technique is gradually ablated by the laser and several deep channels come into being. When laser ablates the bottom of the channels in the target, the sputtered polymer chains have to pass through the channels to reach the outside, during which they unavoidably collide with the wall of channels and lose most of the energy. The polymer chains in low energy state will become coiled with each other and finally cause the accumulative structural disorder in nanofilm, leading to the decline of crystallinity. Please see yellow highlight in Lines 7-17 of Page S4 and Fig. S64 of Page S69 in Supporting Information. This work is pretty new, and we are learning on it. We are working on optimizing the design of equipment and have confidence to avoid this problem in our future work.\nResponse: Thank you for the reviewer’s comment. We are sorry for the confusing. The lower work function of nanofilm is benefit for improving the interface matching between metal electrodes and semiconducting nanofilm, which would facilitate the charge transport in the whole electronic device. We have modified the related statement. Please see yellow highlight in Lines 20-23 of Page 5 in the Manuscript and Lines 23-25 of Page S5 in the Supporting Information.\nResponse: Thank you for the reviewer’s comments. Disorder is the intrinsic property of semiconducting polymer due to its long polymer chain, complex chain conformation and conjugation. In our structure characterization, we have found the characteristics of imperfect crystallization of the polymer chain in 3D-ED data as illustrated in Lines 2-7 of page 4 in the Manuscript, so that the hopping could occur between these regions. Therefore, in our work, the VRH theory is adopted to explore the charge transport in our nanofilm. We have changed the explanation. Please see yellow highlight in Lines 39-42 of Page 5 in the Manuscript.\nResponse: Thank you for the reviewer’s suggestion. These references are very helpful and we have added them in Table S13 of Supporting Information.\nResponse: Thank you for the reviewer’s comment. According to the TGA and DSC results, PANI is rather stable in temperature below 100 oC (373 K). Please see Fig. S53 in page S58 of Supporting Information. In addition, we also observed the morphology of PANI nanofilm after the high-temperature annealing under 150 oC (423 K), which exhibited no significant change compared to the untreated nanofilm. Please see Figs. S52b and S58b of Supporting Information. Based on the above evidences, it is reasonable to exclude the influence of morphology change on the charge carrier mobility of nanofilm.\nResponse: Thank you for the reviewer’s comment. The PANI chains in nanofilm have been partially de-doped so that some dopant sulfates remain in the nanofilm, which point to the S element discovered by XPS. We have modified related statements to make them more accurate. Please see yellow highlight in Lines 36-38 of Page 2 in the Manuscript.\nResponse: Thank you for the reviewer’s comment. The thickness of PANI nanofilm could be manipulated by controlling the deposition time. Normally, a 30-min deposition process could produce the nanofilm with thickness of ~230 nm. We have also prepared nanofilm with different thicknesses and their characterizations are summarized in Supplementary Note 3. Please see yellow highlight in Line 41 of Page S3 and Table S7 of page S79 in the Supporting Information.\nResponse: Thank you for the reviewer’s comment. Actually, there is few reports on the high crystalline conducting polymer nanofilm, except for Prof. Feng’s group. We have rearranged the Introduction part and enriched the information for their related works. Please see yellow highlight in Lines 1-6 of Page 2 in Manuscript.\nResponse: Thank you for the reviewer’s comments. The crystallinity of poly(3-alkylthiophenes) is achieved by introducing alkyl side-chains into the chain structure of polythiophene. The parallel arrangement of side-chains could stabilize the π-π stacking of the main chain and regulate the crystallization kinetics, benefiting the crystalline process. However, this method is only applicable for semiconducting polymers with specialized chain structure (i.e. long alkyl side-chains). These side-chains will also block the intrachain transport of charge carriers and decline the electrical performance of semiconducting polymers. Thus, in this work, we try to put forward a technique to realize the crystallinity of general semiconducting polymer without specific functional groups. We have clearly explained the mechanism in the crystallinity of poly(3-alkylthiophenes), please see yellow highlight in Lines 37-41 of Page 1 in Manuscript.\nResponse: Thank you for the reviewer’s suggestion. The single-crystalline characterization of our PANI nanofilm have been confirmed by GIXRD, HRTEM, SAED and 3D-ED. We have tried to collect the SCXRD and POM results, but those characterizations are not suitable for our nanofilm since our nanofilm only has the thickness of 100-300 nm. To further confirm the single-crystalline characteristic in our nanofilm, we have recorded the GIWAXS patterns from multiple regions of nanofilm using two-dimensional detector with the sample-detector-distance of 137 mm. The testing regions can cover most of nanofilm. The completely consistent results prove that all parts of our nanofilm displays the same single-crystalline characteristic. Please see Lines 23-25 of Page S1 and Fig. S67 of Page S72 in Supporting Information.\nResponse: Thank you for the reviewer’s comments. (1) PSS was removed because the PANI was partially de-doped during the MAPLE process, which was proved by XPS results and DFT simulations. We have presented the characterizations and discussions in Supplementary Note 2. Please see yellow highlight in Lines 16-28 of Page S3 in Supporting Information. (2) Molecular weight was measured with gel permeation chromatograph (GPC) and the PANI in nanofilm was dissolved by dimethyl sulfoxide (DMSO). We have provided the details in Method. Please see yellow highlight in Lines 12-13 of Page 15 in Manuscript. (3) The radius of gyration was derived from the X-ray scattering data using the Guinier approximation equations. We have provided the details of data processing in Supplementary Note 1-(2). Please see yellow highlight in Lines 26-28 of Page S1 in Supporting Information.\nResponse: Thank you for the reviewer’s comments. PSS had a strong electrostatic attraction with proton-doped PANI chains because PSS had negative charges and proton-doped PANI gained positive charges. When PANI chain was partially de-doped during the MAPLE process, its positive charges were reduced, which declined the electrostatic attraction between PANI and PSS. Meanwhile, PSS had a strong hydrogen bonding with methanol, so that PSS chain was dragged by the massive methanol molecules (98 wt%) and they formed molecular clusters. The low sticky coefficient and high vapor pressure of methanol made them to be easily removed by the vacuum pump. We have presented the detail process in Supplementary Note 2. Please see yellow highlight in Lines 16-28 of Page S3 in Supporting Information. The absence of PSS was confirmed by XPS results and DFT simulations, rather than AFM-IR results. We used AFM-IR only to verify the deposition of PANI on the substrate, not for the confirmation of absence of PSS. We apologize for the misunderstanding and have modified the related explanation. Please see yellow highlight in Page 2 Line 39 of Manuscript.\nResponse: Thank you for the reviewer’s suggestion. We have provided the testing details for the thermoelectric, magneto-thermoelectric, magnetoresistance and photoconductive performance. Please see yellow highlight in Lines 24-40 of Page 15 in Manuscript. The calculation equations of Seebeck coefficient, power factor, on/off ratio have been listed in Supplementary Note 1-(4). Please see yellow highlight in Lines 6-8 and Lines 11-14 of Page S2 in Supporting Information. The voltage response under various temperatures has been tested for the nanofilm since it is necessary for calculating the Seebeck coefficient. Please see Fig. S22 in Page S27 of Supporting Information.\nResponse: Thank you for the reviewer’s suggestion. We have rearranged the Supporting Information and added contents to make it more readable. Please see Contents in Supporting Information.\nResponse: Thank you for the reviewer’s suggestion. We have provided the thermoelectrical, magnetoresistance and photoconductive performance of MAPLE prepared PPy nanofilm and spin-coated PPy film in Supplementary Note 7. Please see yellow highlight in Lines 26-41 of Page S5 in Supporting Information. Derived from the SQUID results, the MAPLE prepared PPy nanofilm gains a higher N(E ) than that of spin-coated PPy film, which means that PPy nanofilm also displays a narrower DOS distribution around Fermi level. Please see yellow highlight in Lines 37-41 of Page S5 in Supporting Information.\nResponse: Thank you for the reviewer’s suggestion. After extending the deposition time over 40 min, the frozen target in MAPLE technique is gradually ablated by the laser and several deep channels come into being. When laser ablates the bottom of the channels in the target, the sputtered polymer chains have to pass through the channels to reach the outside, during which they unavoidably collide with the wall of channels and lose most of the energy. The polymer chains in low energy state will become coiled with each other and finally cause the accumulative structural disorder in nanofilm, leading to the decline of crystallinity. We have added the detailed explanation in Supplementary Note 3. Please see yellow highlight in Lines 7-18 of Page S4 in Supporting Information.\nResponse: Thank you for the reviewer’s comments. Our results confirm that there is relationship between the crystallinity or molecular ordering of the PANI nanofilm and magnetic sensitivity. The single-crystalline characteristic of our nanofilm bring it high magnetic sensitivity, since it exhibits a high magnetoresistance sensitivity of 3.38% T-1 under low magnetic field of 400 mT, which is nine times higher than 0.37% T-1 of spin-coated film with poor crystalline structure. Please see yellow highlight in Lines 38-40 Page 6 of Manuscript.\nAs for the electronic states, the Density of States at the Fermi level (N(E )) of our nanofilm is very sensitive to the magnetic field, which is increased from 5.691023 to 2.301024 state eV-1 m-3 when magnetic field strength reaches 3 T. For comparison, the N(E ) of spin-coated film only exhibits a slight increase from 1.381022 to 2.751022 state eV-1 m-3. This means that, our nanofilm with highly-ordered crystalline structure gains a narrowed DOS distribution under magnetic field. We have added related statement. Please see yellow highlight in Lines 13-18 of Page 5 in Manuscript.\nResponse: Thank you for the reviewer’s comments. To test the electrical conductivity, the PANI bulk has been pressed into a disc with a diameter of 1.5 cm and thickness of about 0.1 cm and its electrical conductivity is 4.82 S cm-1. The electrical conductivity of bulk and nanofilm could not be compared since they have huge disparity in thickness. The spin-coated film with thickness similar to nanofilm (in the level of hundred nanometers) has been prepared and its electrical conductivity is only 1.46 S cm-1, which is lower than 1.71 S cm-1 of our nanofilm. It means that our nanofilm with high crystallinity gains a higher conductivity compared with the spin-coated film.\nResponse: Thank you for the reviewer’s comment. We have carefully modified and rearranged our manuscript according to all the reviewers’ suggestions.\nWe hope this revision will meet the standard for publication in Nature Communications."}, {"round": 2, "reviewer_comments": {"reviewer_1": "I thank the authors for addressing my comments.\n1. I remain concerned about the use of the term “single crystalline” to describe the entire thin film that clearly contains multiple crystalline domains. As such, the revised title still appears inaccurate. This terminology also persists in the figure captions—for example, see Figure 1. Additionally, the manuscript primarily focuses on one polymer, PANI, while PPy is mentioned only briefly in a single line toward the end. Yet, the title implies a broader scope. A more accurate and specific title might be: “PANI Films with Large Single Crystalline Domains”, which better reflects the content and contribution of the work. Alternatively, the authors could consider a title that emphasizes the method, which is indeed the central focus of the manuscript. Ultimately, I will defer to the editor and authors to determine the most accurate and representative title that aligns with the manuscript’s actual scope and findings.\nReviewer 3 also raises this issue of single crystallinity. The authors provide Fig S67 as their response and the peaks are not sharp and there is a broad background indicating an amorphous phase. The GIXRD is consistent with a highly oriented semicrystalline film.\n2. Authors' response to my Q1 and Q2 should be incorporated into the manuscript so that it sets the stage for their work but after some thought and revision. Some of their distinctions seems to be quibbles (nano-scaled single crystal vs large scaled nanofilm or dendritic crystal of PANI). Also, most conjugated polymers have alkyl functional groups. Yet, they dismiss alky chains of P3HT as \"specialized functional group\". Rather than focusing on these semantic distinctions, the authors could strengthen their argument by acknowledging prior efforts to crystallize conjugated polymers, citing relevant literature where partial success has been achieved. They can then emphasize the remaining challenge: the fabrication of large-area films with large crystalline domains. This is the key contribution their manuscript aims to make, and framing it this way would enhance the clarity and impact of their narrative.\n3. Their answer to my Q4 shows the current limitation of their approach in terms of film thickness. That should be clearly stated in the manuscript.\n4. Q6: In the modified manuscript, they say imperfect crystallization. It is just that there are amorphous domains. This is a feature of polymers as it has to pay a high entropy cost to get a single crystal. I think the authors should rewrite this simple as \"our nanofilms still contains amorphous domains\"\n5. In response to reviewer 3's query about poly(3-alkylthiophenes), the authors write that \"These side-chains will also block the intrachain transport of charge carriers and decline the electrical performance of semiconducting polymers\" This is not true. The reported conductivity here is around 4 S/cm (Extended data figure 3). Often polymers with sidechains have conductivities around 1000-3000 S cm-1. I feel that the author can expand on why it is difficult to crystallize polymers without side-chains i.e clearly state the fundamental thermodynamic and kinetic factors that needs to be altered to get the polymers to crystallize.\n6. With regard to PSS query by Reviewer 3, Figure 1d still shows the sulfur peak. What is the source of sulfur is PSS is not there. One would imagine that the dedoping may convert sulfonate to sulfonic acid, which can alter the XPS spectra. But the XPS shows an intense S2p peak. Can the authors explain the origin of the peak?\n7. In response to the Reviewer 3's query that about conductivity, the authors write \"The spin-coated film with thickness similar to nanofilm (in the level of hundred nanometers) has been prepared and its electrical conductivity is only 1.46 S cm-1, which is lower than 1.71 S cm-1 of our nanofilm. It means that our nanofilm with high crystallinity gains a higher conductivity compared with the spin-coated film.\" I doubt that 1.46 is that different from 1.71 and of course difficult to compare without standard deviations. This experiment also raises the question whether one needs their method to get to high conductivity.\nI hope these comments are useful to enhance the impact of their manuscript.", "reviewer_2": "The authors well addreessed my concerns well. It can be recommended for publication."}, "author_response": "Response: Thank you for the reviewer’s valuable comments and suggestions. After careful consideration of suggestions, we thought that the title of our work is better to change to “Highly oriented semiconducting polymer nanofilm with enhanced crystallinity”. Please see yellow highlights in the title. The main reasons are as follows:\n1) In the manuscript, we not only prepare polyaniline, but also fabricate polypyrrole to confirm the generality of our technique. Therefore, we think it’s better to use “semiconducting polymer”. Especially, we have done all the performance tests for polypyrrole as well. 2) Our nanofilm does contains highly oriented crystalline structure and high crystallinity up to 89.6%.\nBesides, for accuracy, we have changed the expression of “single-crystalline semiconducting polymer” to “highly oriented semiconducting polymer” in the whole manuscript as suggested by the reviewer. Please see yellow highlights in the caption of Fig. 1, line 9 and line 17 in page 2, line 5 and line 11 in page 8.\nResponse: Thank you for the reviewer’s comments. It’s true that the key contribution of our work is the fabrication of nanofilm with enhanced crystallinity. After careful consideration of reviewer’s suggestion, we have changed this part to the following: “So far, the crystals of semiconducting polymer like polyaniline (PANI), polypyrrole (PPy), and poly(3-alkythiophenes) have been achieved through vapor phase polymerization or solution process methods8,9. However, the controllable fabrication of large-area semiconducting polymers nanofilm with enhanced crystalline structure remains a long-standing challenge, which severely limits the industrial application of semiconducting polymers in the electronic device.”. Please see yellow highlights in lines 37-41 of page 1 and line 1 of page 2.\nResponse: Thank you for the reviewer’s comments. We have added this in the manuscript as suggested by reviewer. Please see yellow highlights in lines 30-33 of page 5.\nResponse: Thank you for the reviewer’s valuable suggestion. After careful consideration, we have changed the expression to “The 3D-ED data show discrete diffraction spots consistent with single crystal diffraction, while the diffraction intensity and the fluctuation in their position may be from the uneven length of polymer chain segments along the polymer chain direction (c-axis), that possibly cause the dislocation and defect in the crystal of polymer as well as formation of amorphous phase.” Please see yellow highlights in lines 4-8 of page 4.\nResponse: Thank you for the reviewer’s comments. Since we have changed introduction part as suggested by reviewer in Q2, we think we don’t need to add this in the manuscript right now. Actually, as we mentioned before, the side-chains could stabilize the π-π stacking of the main chain and regulate the crystallization kinetics to help crystallization of polymer chain, while the polymer without side chain needs to cross very high activation energy and kinetic barrier to the rearrangement of chain conformation for achievement of crystallization. We have mentioned this in the introduction already. Please see yellow highlights in lines 34-37 of page 1.\nResponse: Thank you for the reviewer’s comments. Sorry for the misleading. Actually, in the Methods part, we have described the synthesis process of polyaniline. Please see yellow highlights in lines 3-4 of page 15. Normally, the synthesis of polyaniline should be conducted in an acidic solution with a pH value < 5. As a polymeric electrolyte, the pH value of PSS solution is not enough for the polymerization of aniline, so we have to add the sulfuric acid into the solution. In this situation, sulfur element in the synthesized PANI/PSS comes from both the PSS and sulfate, whose binding energy peaks in XPS spectra are different, as shown in Figure 1c. When PANI is partially dedoped, the sulfur element only comes from the sulfate, as shown in Figure 1d. that’s why we could confirm that PSS has been removed during our nanofilm preparation. Please see binding energy peaks marked in Figure 1c and 1d, and yellow highlights in line 37 of page 2.\nResponse: Thank you for the reviewer’s comments. In fact, we provided the electrical conductivity of nanofilm and spin-coated film according to the requirement of Reviewer 3, but we think it is useless to make a comparison between them. The reason is that, the electrical performance of semiconducting polymer is not determined by its electrical conductivity, but by its electronic structure like the distribution of DOS. This means that the high electrical conductivity doesn’t directly lead to the high electrical performance. For semiconducting polymer, the polydispersity of its molecular weight and structure disorder make the energetic disorder in the electronic structure (Nat. Commun. 2020, 11, 1737.). The electronic structure plays a key role in the electrical performance of semiconducting polymer. By managing the chain conformation, orientation and crystallinity of semiconducting polymer in our nanofilm, its electronic structure has been promoted. For example, our nanofilm gains a much higher N(E ) and narrowed DOS distribution compared to those of spin-coated film as we mentioned in the manuscript. This optimized electronic structure brings our nanofilm extraordinary thermoelectrical, magnetoresistance and photoconductive performances, which are much better than those of spin-coated film. Please see yellow highlight in lines 11-13 of page 5, lines 35-38 of page 6, line 45-46 of page 6 and line 1 of page 7, lines 2-4 of page 7.\nResponse: Thank you for the reviewer’s comments. These comments are very useful for facilitating the impact of our work. We do thank the reviewer’s meticulous work."}, {"round": 3, "reviewer_comments": {"reviewer_1": "The authors have addressed my concerns. I support the publications of this manuscript."}, "author_response": "Response: Thank you for the reviewer’s recognition. Hopefully, our work can make the impact on the field with the publication of our manuscript."}]

Decision letter