# A Platinum (II) Polyyne Oligomers Donor for Efficient Ternary Organic Solar Cells

Abdel Aziz Wayzani, Léo Boivin, Romuald Herbinet, Muriel Durandetti, Paul-ludovic Karsenti, Fabrice Muller, Christophe Sinturel, Loïc Le Pluart, Pierre Harvey, Ganesh Sharma, et al.

► To cite this version:

Abdel Aziz Wayzani, Léo Boivin, Romuald Herbinet, Muriel Durandetti, Paul-ludovic Karsenti, et al. A Platinum (II) Polyyne Oligomers Donor for Efficient Ternary Organic Solar Cells. Solar RRL, 2025, 10.1002/solr.202500663. [hal-05415048](https://HAL Id: hal-05415048)

https://normandie-univ.hal.science/hal-05415048v1

Submitted on 23 Jan 2026

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons CC BY 4.0 - Attribution - International License
RESEARCH ARTICLE

OPEN ACCESS

# A Platinum (II) Polyyne Oligomers Donor for Efficient Ternary Organic Solar Cells

Abdel Aziz Wayzani<fnref n="1" /> | Léo Boivin<fnref n="2" /> | Romuald Herbinet<fnref n="1" /> | Muriel Durandetti³ | Paul-Ludovic Karsenti<fnref n="2" /> |
Fabrice Muller⁴ | Christophe Sinturel⁴ | Loïc Le Pluart<fnref n="1" /> | Pierre D. Harvey<fnref n="2" /> | Ganesh D. Sharma⁵ |
Cyprien Lemouchi<fnref n="1" />

**Correspondence:** Christophe Sinturel (christophe.sinturel@univ-orleans.fr) | Loïc Le Pluart (loic.le_pluart@ensicaen.fr) | Pierre D. Harvey (Pierre.Harvey@USherbrooke.ca) | Ganesh D. Sharma (gdsharma@lnmiit.ac.in) | Cyprien Lemouchi (cyprien.lemouchi@ensicaen.fr)

**Received:** 5 September 2025 | **Revised:** 10 November 2025 | **Accepted:** 20 November 2025

**Keywords:** aggregation | donor-acceptor systems | nanostructures | organic solar cells | ternary blend

## ABSTRACT

A ternary organic solar cell (TOSC) P5:PC71BM:Y6 (1:0.2:1) composed of an electron donor 3,4-ethylenedioxythiophene (EDOT)/ diketopyrrolopyrrole (DPP)-containing [Pt] (II) polyyne oligomer P5 with the acceptors PC71BM and Y6 shows a significant enhancement of the average power conversion efficiency (PCE) to 16.0% in comparison to the reported binary organic solar cells (OSCs) (P5:PC71BM (1:1.4), PCE = 9.4%; P5:Y6 (1:1.2), PCE = 14.8%). Photophysical investigations carried out on the two binaries and on the ternary highlight the role of PC71BM to increase the rise time of electron transfer and to decrease recombination processes. Investigations of Y6-containing active layers by atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HR-TEM) show the presence of fibers, which highlights the assistance of Y6 in the nanostructuration of the blends. The higher PCE of the TOSC is explained with larger values of short-circuit current density (Jsc) from a broader absorption range and a superior value of fill factor (FF) supported by the faster mobilities and more balanced μe/μh. This work spotlights the beneficial role of the two acceptors in the TOSC. It explains the achievement of the highest average PCE of 16.0% for [Pt] polyyne oligomers to this date.

## 1 Introduction

Organic solar cells (OSCs) based on solution-processed bulk heterojunction (BHJ) active layer undergo rapid developments, driven by their unique advantages including lightweight, mechanical flexibility, low-toxicity, semitransparent with large area device processing. The path to their commercial application requires the enhancement of their power conversion efficiency (PCE) [1–5]. The PCE of binary BHJ OSCs with conjugated polymers as donors (eg., PM6) has been boosted to 18–19% [6] using low bandgap fused-ring acceptors (FREAs), also named

nonfullerene acceptors (NFAs) (eg., Y6, BTP-Ec9, L8-BO) [6–10]. Enhancements by improving optical, electronic, and optoelectronic properties generally rely on structural modifications of the donors and acceptors, such as halogenation [11–14], alkyl side chain engineering [15], development of biaxially conjugated [16], and larger dipole moment compounds [17]. Morphology of the active layer has a strong impact on the performance. Modifications of the molecular structure of donors can promote their aggregation into fibers, which are suitable structures to improve PCE by maximizing exciton diffusion with larger

Abdel Aziz Wayzani and Léo Boivin contributed equally to this work.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

© 2025 The Author(s). *Solar RRL* published by Wiley-VCH GmbH.

<footnote n="1">¹University Caen Normandie, ENSICAEN, Univ Rouen Normandie, INSA Rouen Normandie, CNRS, Institut CARMEN UMR 6064, Caen, France |</footnote>

<footnote n="2">²Département de chimie, Université de Sherbrooke, Québec, Canada | ³University Rouen Normandie, INSA Rouen Normandie, Univ Caen Normandie, ENSICAEN, CNRS, Institut CARMEN UMR 6064, Mont-Saint-Aignan, France | ⁴Université d'Orléans, CNRS, ICMN, Orléans cedex, France | ⁵LNM Institute of Information Technology (Deemed University), Department of Physics Rupa ki Nangal, Rajasthan, India</footnote>
donor/acceptor interface for their dissociation and transport of
charges to the electrodes [18–20]. Conjugated organometallic
metallooligomers are an appealing type of donors [21]. Over
the two decades, poly(metalla-ynes) gained considerable atten-
tion for several applications such as photovoltaics, nonlinear
optics, organic light-emitting diodes (OLEDs), organic field-effect
transistors (OFETs) or molecular wires [22]. This class of mate-
rial is defined with their rigid-rod-type structure composed of a
transition metal ion such as Pt(II) connected to the alkynyl units
with the platinum polyyne oligomers. The binding energy
between the metal and alkynyl organic part explains the interest-
ing optical, electronic, and optoelectronic properties. The pres-
ence of Pt(II) promotes spin-orbit coupling (SOC) and induces
intersystem crossing (ISC), which improves the photolumines-
cence (PL) quantum yield for OLED [23]. Incorporation of metal
as platinum(II) in conjugated polyyne oligomers brings enhance-
ment of the PCEs [24]. It is explained by their good photostabil-
ity, high absorption capacity over a wide range of absorption
wavelengths. The energy levels of the frontier molecular orbitals
(MOs), the lowest unoccupied molecular orbital (LUMO), and
the highest occupied molecular orbital (HOMO) are readily mod-
ified by changing the alkynyl organic part. These organometallic
compounds exhibit superior charge transport with respect to
metal-free compounds, explained by a better aggregation driven
by intermolecular Pt...Pt interactions combined with π–π stack-
ing of conjugated backbones [25]. Pt(II) complexes favor and pro-
vide ultrafast photo-induced electron transfer (~100 to 200 fs)
which maximizes electron-hole pair generation [26–28]. It was
noticed in our previous work with the obtention of superior
PCE for [Pt(II)] polyyne oligomers with PCEs in respect to
Pt(II)-free analog systems [26–28]. It was supported by the work
of Peng et al., which reported an enhancement of PCE from
13.03% to 16.35% with the incorporation of a platinum(II) com-
plex into the backbone of the conjugated copolymers blended
with the acceptor Y6 [24]. However, such binary OSCs have nar-
rower absorption spectrum coverage, and the morphology of
their active layer must be improved, which limits the enhance-
ment of the PCE. The preparation of ternary organic solar cells
(TOSCs), consisting of two donors and one acceptor [29] or one
donor and two acceptors, can tackle those issues [30, 31]. Hence,
the preparation of a TOSC with the [Pt] polyyne oligomers as the
donor blended with two acceptors motivates this work for a sig-
nificant increase in the PCE. It would be the first reported exam-
ple in the best of our knowledge. For example, the group of Wang
et al. reported the preparation of TOSC with layer-by-layer depo-
sition method, composed of D18 as donor and the two acceptors
L8-ThCl:L8-BO with a certified efficiency of 20%, which is higher
than the PCE of the binary D18:L8-BO at 19% [20]. Superior per-
formances are explained by the nanoscale fibrillar structures, the
increase of short-circuit current density (J<sub>SC</sub>), fill factor (FF),
open-circuit voltage (V<sub>OC</sub>) values, and longer lifetime of charge
carriers due to better controllable exciton diffusion length [32].
Hence, the choice of the third component is crucial to result in
synergetic effects. The complementarity of the absorption spectra
between the three components widens the range of absorption
wavelength and increases photon harvesting, which yields to
larger value of external quantum efficiency (EQE) and J<sub>SC</sub> [33].
In addition, by selecting appropriate components, the morphol-
ogy of the active layer can be further improved by favoring nano-
segregation between the donor and acceptor components for the
optimization of exciton dissociation [33–36]. Molecular stacking

can be regulated to increase hole (μh) and electron (μe) mobilities
with a balanced ratio (μe/μh ~ 1), reducing charge recombination
and maximizing their collection at the electrodes [33]. This con-
tributes to larger FF [33]. For ternary active layer, PC71BM is an
appealing third component to simultaneously favor nanosegrega-
tion and regulate molecular stacking [37]. However, it is still
challenging to design a TOSC with a higher VOC than the binary
active layer because of the stabilization of the LUMO energy level
from the formation of an alloy between PC71BM and the second
acceptor [33, 38]. Sun et al. reported an increase in the PCE from
17.10% to 18.02% by introducing 15 wt% of PC71BM to the binary
active layer PM6:L8-BO [34]. The larger JSC value of the ternary is
explained by a widened EQE spectrum favored by the absorption
complementarity between PC71BM (300–600 nm) and PM6:L8-
BO (450 to 900 nm) [34]. From its spherical conjugated structure,
PC71BM plays the role of morphology regulator, thus increasing
FF [37–39]. Its higher miscibility with most donor and acceptor
materials leads to higher interpenetration between the donor and
the acceptor with optimized phase segregation at the nanoscale
and prolonged molecular stacking [37–39]. Isotropic electron
transport is favored, exhibiting higher and more balanced charge
mobilities and reduction of the recombination process. Energy
levels of its frontier MO match those of most donors and accept-
ors for the optimization of charge transfer. Sun et al. studied the
influence of PC71BM weight ratio blended with PM6 and L8-BO
on the PCEs of TOSCs. VOC increases with a larger content of
PC71BM, while the values of FF and JSC reach a maximum before
decreasing [34]. Hence, a small amount of PC71BM (5–15 wt%)
increases the PCE [34].

Our previous work reported the synthesis and characteriza-
tion of a new conjugated platinum(II) polyyne oligomer P5 built
with diketopyrrolopyrrole (DPP), 3,4-ethylenedioxythiophene
(EDOT), and platinum(II)-diyne units. An average PCE of 14.8%
for a binary BHJ OSC P5:Y6 (1:1.2) was achieved, which is
significantly better than that of P5:PC71BM (1:1.4) at 9.4% [28].
The chemical structure of P5 composed of trans-bis(phosphine)
diethynylplatinum(II) units ([Pt]-complexes) and DPP/EDOT
segments, explained the good performances. The molecular
structures of P5, PC71BM, and Y6 are displayed in Figure 1a.
Synergic effects between the [Pt]-units and the composition of
the heterocycle sequence for P5 contribute to superior PCEs
in comparison with analogs such as DPP-EDOT-containing con-
jugated polymers [40] and DPP-containing conjugated polymers
in TOSC [41, 42] and [Pt] and DPP-containing polyynes [26, 27]
as donors. Wider absorption range of wavelengths, ultrafast
photo-induced electron transfer, and improvement of charge
transport by enhanced aggregation explained the better perform-
ances as discussed before and evidenced in our previous works.

This work reports the preparation of a new ternary BHJ OSC P5:
PC71BM:Y6 (1:0.2:1) with superior performances compared to
DPP-containing donors blended in ternary active layers. The
improvement of the synthetic route of the ligand L5 enables
the synthesis of larger quantities of P5 required for the prepara-
tion of TOSC. The optical, electronic, and optoelectronic proper-
ties of the TOSC are assessed with the morphology of the active
layer and compared to binary OSCs P5:PC71BM (1:1.4) [28] and
P5:Y6 (1:1.2) [28] in order to explain the enhancement of the
average PCE from 14.8% to 16.0%. The novelty of this work con-
sists of 1) the preparation of a ternary active layer consisting of
DPP-containing [Pt] (II) polyyne oligomers P5 as donors with
two acceptors PC<sub>71</sub>BM and Y6. It highlights for the first time, the combined benefits of [Pt]-complexes and ternary active layer to increase the PCE, 2) the role of PC<sub>71</sub>BM to shorten electron transfer time and reduce recombination, and 3) the observation of fibers when Y6 is added in active layers. A full investigation of optical, electronic, and optoelectronic properties explains this enhancement. The comparative investigation of photophysical properties for binary and ternary active layers evidences the impact of PC<sub>71</sub>BM to shorten the electron transfer time scale from P5 to the acceptors, which prevents charge recombination. The increase of EQE, *J*<sub>SC</sub>, FF values, and charge/hole mobilities with longer lifetime of excitons and their easier dissociation contribute to the superior PCE of this new TOSC, which is in line with the observation of fibers in the active layer as revealed by atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HR-TEM). The average PCE of 16.0% (*PCE*<sub>max</sub> = 16.2%) for P5:PC<sub>71</sub>BM:Y6 (1:0.2:1) is the highest PCE reported for any [Pt] (II) polyyne oligomers to this date.

## 2 | Results and Discussion

### 2.1 | Synthesis of the Donor [Pt] Polyyne Oligomers P5

The fabrication of TOSCs requires the preparation of a larger quantity of P5. The synthetic protocol of the ligand L5 has been modified in comparison to our previous work [28]. In the Stille cross-coupling reaction, the use of the intermediate 2b (R = n-butyl) led to a global yield of 40%, which is two times higher than the previous reported 20% yield (the use of 2a R = CH3, Scheme 1). All details regarding this modified procedure are available in supporting information (Scheme S1, SI).

Ligand L5 was synthesized in the 350–400 mg scale from intermediates 2b and 3 and was characterized by ¹H and ¹³C NMR (Figures S1 and S2, SI). In our previous work, the [Pt]-oligomer P5 was prepared after a CuI-catalyzed dehydrohalogenation from L5 and freshly prepared *trans*-PtCl₂(PBu₃)₂. It was fully characterized by ¹H, ³¹P NMR, and GPC (Figure S3, S4, and S5, SI). The data are in agreement with those previously reported [28].

### 2.2 | Optical and Electrochemical Properties

Ternary active layers have been prepared by mixing PC<sub>71</sub>BM with the narrow bandgap NFA Y6 and the donor P5 to investigate their photovoltaic performances. The chemical structures of P5, PC<sub>71</sub>BM, and Y6 are displayed in Figure 1a. The widening of the absorption range of the ternary active layer is crucial to enhance photon harvesting. In comparison to the binary active layer P5:Y6, the ternary active layer containing PC<sub>71</sub>BM, P5, and Y6, absorbs in a wider range from 300 to 900 nm (Figure S6, S7, and S8, SI). Normalized UV-visible absorption spectra of the neat films of donors and acceptors (Figure 1b) show that PC<sub>71</sub>BM has a strong absorption in the range of 300–600 nm with a maximum absorption peak at 390 nm. This band complements that of P5 from 500 to 800 nm with a maximum absorption peak at 736 nm, and that of Y6, which absorbs from 600 to 930 nm with a maximum absorption peak at 828 nm. Despite the fact that the absorption coefficient ε<sub>λ</sub> of PC<sub>71</sub>BM is smaller than that of P5 and Y6 (PC<sub>71</sub>BM, ε<sub>392</sub> nm = 2.45 × 10<sup>4</sup> mol<sup>-1</sup> L cm<sup>-1</sup> vs P5, ε<sub>736</sub> nm = 2.12 × 10<sup>6</sup> mol<sup>-1</sup> L cm<sup>-1</sup> vs Y6 ε<sub>828</sub> nm = 2.46 × 10<sup>5</sup> mol<sup>-1</sup> L cm<sup>-1</sup>), supplementary absorption range from PC<sub>71</sub>BM contributes to the increase of EQE between 300 and 600 nm, as evidenced by the EQE spectrum (Figure 4b). The LUMO and the HOMO of P5 estimated from onset reduction and oxidation potentials, respectively, measured from cyclic voltammetry (CV), are the same as those reported [28]. The MO energy levels of PC<sub>71</sub>BM match well with those of P5 and Y6, thus securing downhill thermodynamic cascade (Figure 1c). The LUMO energy level of Y6 (−4.06 eV) lies between those of P5 (−3.80 eV) and PC<sub>71</sub>BM (−4.15 eV). Efficient large charge separation to maximize exciton spitting is aided by the downhill cascade of the LUMO manifolds. The HOMO energy manifold of Y6 (−5.64 eV) is positioned between those of P5 (−5.30 eV) and PC<sub>71</sub>BM (−6.08 eV), leading to efficient hole extractions [43].

To provide information on the electron transfer processes between P5 and the acceptors PC<sub>71</sub>BM and Y6 leading to the dissociation of excitons, the PL spectra have been recorded exciting cast film at a wavelength of 600 nm from cast films. PL intensity of P5 is totally quenched in the cast films of P5:PC<sub>71</sub>BM (1:1.4),

<figure><img src="image_2.png" /><figcaption>**SCHEME 1** | Synthetic route for the preparation of ligand L5 after a Stille cross-coupling reaction between 3 and 2a or 2b (TIPS : triisopropylsilyl group), i) n-BuLi 1,6 M in hexane (1.5 eq.), Bu₃SnCl (1.1 eq.), THF, -75°C, then at RT, overnight; ii) PdCl₂(PPh₃)₂ (34 mol%), PPh₃ (70 mol%), DMF, 80°C, 2h; followed by the synthesis of [Pt]-oligomer P5; and iii) TBAF (1 M in THF, 2 eq.), *trans*-PtCl₂(PBu₃)₂ (1 eq.), CuI (0.1 eq.), CH₂Cl₂/Et₃N, RT, 3d.</figcaption></figure>
<figure><img src="image_3.png" /><figcaption>**FIGURE 1** | (a) Chemical structures of P5, PC71BM, and Y6. (b) Normalized UV-vis spectra of P5, Y6, and PC71BM neat films. (c) Energy level diagrams of P5, Y6, and PC71BM (from the results of CV measurements).</figcaption></figure>

P5:Y6 (1:1.2), and P5:PC71BM:Y6 (1:0.2:1) (Figures S9 and S10, SI), which is attributed to efficient electron transfer between P5 and each electron acceptor. It supports efficient photoinduced electron transfer from P5 and PC71BM and Y6. These measurements demonstrate the efficient dissociation of excitons at donor/acceptor interfaces, followed by the electron transfer from P5 to acceptors in binary and ternary active layers.

## 2.3 | Steady State Spectroscopy

Absorption, excitation, and fluorescence spectra of P5, PC71BM, and Y6 in solution and as thin films are illustrated in Figure S11, SI. Two species have been detected from the decay-associated spectra with emission lifetimes of 44.7 ps (major component) and 241 ps (minor component; the IRF is ~15 ps). This timescale is consistent with data reported by Albert-Seifried et al. [44]. Figure 2 exhibits the time-resolved associated fs-TAS of P5, PC71BM, and Y6, along with those of P5:PC71BM (1:1.4), P5:Y6 (1:1.2), and P5:PC71BM:Y6 (1:0.2:1) blends. The corresponding time evolution of the fs-TAS is placed in Figure S12, SI. The shapes of the transient signals (negative part of the spectra; the bleached signals are the ground state species in the Δ*T/T* scale) permit a primary visual assignment of the various species appearing in the fs-TAS of the blends. For example, in the P5:PC71BM blend, the bleached band at ~730 nm corresponds to P5, whereas the broad peak formed in the fs time scale at ~1100 nm is the transient PC71BM⁻. This radical anion then evolves in the ps time scale (i.e., between 0.1 and ~1.2 ps) into a new transient at ~900 nm decaying with a long lifetime well above the delay line limit (>8 ns), which is unambiguously attributed to ³PC71BM*.

The overall process can be defined as: ¹P5* + PC71BM → P5⁺⁺ + PC71BM⁻⁻ → P5 + x ³PC71BM* + y PC71BM (x + y = 1). It is noteworthy that the comparison of fs-TAS of the radical cation P5⁺⁺

and neutral P5, and that of the radical anion Y6⁻ and neutral Y6, is very similar to each other due to extended *π*-delocalization and cannot be spectroscopically distinguished. For the P5:Y6 blend, its fs-TAS is reminiscent of both that of Y6 and P5 when comparing the bleached signals below 750 nm, where the two peaks of P5 and the two shoulder-like bands of Y6 coincide. The bleached signal above 850 nm is consistent with a sum of the contributions from P5 and Y6, resulting in a near-zero feature. Moreover, the early and broader transient signal near 935 nm in this binary blend (blue line) appears to be an approximate sum of the transient signals of both P5 and Y6. Finally, for the tertiary blend P5:PC71BM:Y6 (1:0.2:1), the fs-TAS resembles quite well to that of the binary blend P5:Y6 (1:1.2) blend with one noticeable difference. The transient components in the 900–1100 nm region (blue and green traces) exhibit an isosbestic point at ~965 nm, which is reminiscent to that for Y6 alone (at ~975 nm). This feature indicates that neutral Y6, and likely Y6⁻ due to the presence of slightly larger bands for the blend, is present at the early stages of the photo-processes. Importantly, neither the transient signal of PC71BM⁻ at ~1100 nm and of ³PC71BM* at ~900 nm is present in the fs-TAS. This notable absence is due to a combination of a lower relative quantity in the P5:PC71BM (1:1.4) and P5:PC71BM:Y6 (1:0.2:1) blends and kinetics traces. The excited state lifetimes depicted by decay-associated spectra for P5 as film (1.15 ps, 8.23 ps, 77.7 ps, and 7.92 ns; Figure 2) are the same as those previously reported by us (1.1 ps, 8.1 ps, 72 ps, and 6.1 ns), considering the uncertainties [28].

The monitoring of the fs-TAS at various wavelengths (Figures S12, SI) permits to assess to the rise times from two binaries P5:PC71BM (1:1.4), P5:Y6 (1:1.2), and ternary blends P5:PC71BM:Y6 (1:0.2:1), as illustrated in Figure 3. The rise times and *k*et are summarized in Table 1. The rise time < 85 fs of P5:PC71BM (1:1.4) is shorter than that of P5:Y6 (1:1.2) (675 fs),
<figure><img src="image_4.png" /><figcaption>**FIGURE 2** | Comparison of the decay-associated spectra of P5, PC71BM, and Y6, along with those of P5:PC71BM (1:1.4), P5:Y6 (1:1.2), and P5:PC71BM:Y6 (1:0.2:1) blends. The time-dependent fs-TAS is placed in Figure S11, SI.</figcaption></figure>

corresponding to a rate constant of electron transfer ($k_{et} \sim 1$/rise time), $k_{et} > 11.8 \times 10^{12} s^{-1}$ and $1.5 \times 10^{12} s^{-1}$, respectively. It is consistent with previously reported rate for the blend P5:PC71BM (1:1) blend, $k_{et} = 3.5 \times 10^{12} s^{-1}$ [28], and data from literature [45]. For ternary blend P5:PC71BM:Y6 (1:0.2:1), three processes are possible: 1) P5*:PC71BM:Y6 → P5⁺⁺:PC71BM⁻⁻:Y6, 2) P5*:PC71BM:Y6 → P5⁺⁺:PC71BM:Y6⁻⁻, and 3) P5⁺⁺:PC71BM⁻⁻:Y6 → P5⁺⁺:PC71BM:Y6⁻⁻ (Figure 3).

Depending on the process, the rise times are < 90, 460, and 605 fs, which correspond to the following $k_{et}$ values > $11.1 \times 10^{12} s^{-1}$, $1.5 \times 10^{12} s^{-1}$, and $2.2 \times 10^{12} s^{-1}$, respectively. Comparison between binary P5:Y6 and ternary blends P5:PC71BM:Y6 shows that incorporation of PC71BM brings in an extra ultrafast component (<90 fs), reminiscent to that of the P5:PC71BM (1:1.4) blend (<85 fs). Moreover, this added component also shortens

the rise time from 675 to 605 fs for electron transfer from P5 to the acceptors in TOSC. It evidences the postive effect of PC71BM component to increase the rates of charge separation in the blend. Concurrently, the rates of recombination, $k_{rec}$, which correspond to inverse of the relaxation lifetimes, is slower for P5:PC71BM:Y6 in comparison with that of the P5:PC71BM and P5:Y6 blends, when monitoring the two slower components (fast components: $40 \times 10^{10} \rightarrow 29 \times 10^{10} \rightarrow 20 \times 10^{10}$; slow components: $2.9 \times 10^{10} \rightarrow 1.9 \times 10^{10} s^{-1} \rightarrow 1.7 \times 10^{10} s^{-1}$). Hence, the addition of PC71BM in the ternary blend helps to decrease $k_{rec}$, which contributes to the increase in quantity of charge and hole species accumulating in the blend, as desired. These two observations, 1) faster rates of charge separation and 2) slower rates of charge recombination, are in line with this study. However, the presence of the ultrafast component of charge recombination in
<figure><img src="image_5.png" /><figcaption>**FIGURE 3** | Comparison of the rise times of the various photo-induced electron transfers in the P5:PC71BM (1:1.4), P5:Y6 (1:1.2), and P5:PC71BM:Y6 (1:0.2:1) blends.</figcaption></figure>

the ternary blend (220 × 10¹⁰ s⁻¹), a consequence of the PC71BM ingredient, may affect the quantity of charge and hole species in the blend. To assess these kinetic effects, the photovoltaic properties are presented below. Indeed, an enhancement of exciton dissociation and reduction of the recombination process explains the superior performances of TOSC P5:PC71BM:Y6 in comparison to the binary OSC built with P5:Y6.

It is noteworthy that the platinum fragment plays two important roles. First, it secures electronic conjugation across the backbone of the trans-PtL₂(C≡C)₂-containing moiety) L = phosphine) [46]. Second, the presence of platinum promotes an increase in SOC and thus increases the rate of ISC, kᵢₘₐ₄, in Pt(II)-containing polymers, with striking evidence of an intense triplet emission signature at 450 nm arising from the trans-PtL₂(C≡C)₂unit [47]. The timescale for this photophysical process has been determined to be in the order of 1.6–20 ps for this type of motif [48]. In this work, the intersystem process Sₙ ~~~> Tₙ occurs in this timescale, but the downhill cascade Tₙ ~~~> Sₙ is also possible, including down to S₁, with the same time scale. Since the

timescale of photoinduced electron transfer between the excited polymer P5* and the electron acceptor in the blend (here femtosecond, see Figure 2) is faster than that of the one for ISC (in the order of 1.6–20 ps), then the populated S₁ state of P5 contributes significantly to the charge separation in the blend. All in all, the presence of both multiple singlet and triplet upper excited states and a heavy atom, both synergistically contribute to rapidly populate both the S₁ and T₁ states, but concurrently, the S₁ ~~~> T₁ process turns out to be conveniently slower than that of the time scale of the electron transfer (P5* + electron acceptor → (P5)*⁺ + (electron acceptor)*⁻).

## 2.4 | Photovoltaic Characterization

TOSCs have been fabricated with the following common architecture: glass/ITO/PEDOT:PSS/P5:PC71BM:Y6/Al. For comparison purpose, ternary active layers have been prepared in the same conditions as that of binary active layers [28]. The same concentration of P5 of 16 mg.mL⁻¹ has been used for the ternary blend solubilized in chloroform as processing solvent, which was spun coated onto the PEDOT:PSS layer. The thickness of the binary and ternary active layers is similar at 95 nm (±5 nm), measured by ellipsometry. To get information about the effect of incorporation of PC71BM into the host binary BHJ active layer P5:Y6, the weight ratio between the PC71BM, Y6, and P5 has been varied (Table S1, SI). For the TOSC, Vₐ₉ increases slightly with PC71BM doping ratio (Table S1, SI). This outcome may be explained by the formation of transport channels in the active layer. Besides, Jₐ₅₄ and FF reach a maximum for P5:PC71BM:Y6 (1:0.2:1.0). These trends are in line with the study of Q. Sun et al. on the TOSC (PM6:PC71BM:L8-BO) [34]. The best PCE of TOSC was obtained for a weight ratio of 1:0.2:1.0 for P5:PC71BM:Y6 (Table S1, SI and Table 2). This active layer has been treated with solvent vapor annealing (SVA) with THF vapors for 40 s. SVA treatment is a crucial step in the preparation of the active layer to further significantly increase the PCE [28, 49]. The current–voltage (J–V) characteristics under illumination (AM1.5G, 100 mW.cm⁻²) for the ternary OSCs, along with the binary counterpart are shown in Figure 4a, and the corresponding photovoltaic parameters are summarized in Table 2. The optimized TOSC P5:PC71BM:Y6 (1:0.2:1.0) attained the highest PCE of 16.23% (Jₐ₅₄ = 24.98 mA.cm⁻², Vₐ₉ of 0.89 V and FF of 0.73) with an average PCE of 16.04%

<table><caption>**TABLE 1** | Comparison of the kinetic parameters of P5-containing blends obtained from fs-TAS measurements.</caption><thead><tr><th>Blends</th><th>Rise time, fs</th><th>k<sub>et</sub> (10<sup>12</sup> s<sup>-1</sup>)</th><th>Decay time, ps</th><th>k<sub>rec</sub> (10<sup>10</sup> s<sup>-1</sup>)</th></tr></thead><tbody><tr><td>P5:PC<sub>71</sub>BM (1:1) [28]</td><td>—<sup>a,b</sup></td><td>3.5</td><td>—<sup>c</sup></td><td>—<sup>c</sup></td></tr><tr><td>P5:PC<sub>71</sub>BM (1:1.4)</td><td>&lt; 85<sup>b</sup></td><td>&gt; 11.8</td><td>2.5<br>34</td><td>40<br>2.9</td></tr><tr><td>P5:Y6 (1:1.2)</td><td>675</td><td>1.5</td><td>3.5<br>52</td><td>29<br>1.9</td></tr><tr><td>P5:PC<sub>71</sub>BM:Y6 (1:0.2:1) process 1</td><td>&lt; 90<sup>b</sup></td><td>&gt; 11.1</td><td>0.45</td><td>220</td></tr><tr><td>P5:PC<sub>71</sub>BM:Y6 (1:0.2:1) process 2</td><td>605</td><td>1.7</td><td>5.0</td><td>20</td></tr><tr><td>P5:PC<sub>71</sub>BM:Y6 (1:0.2:1) process 3</td><td>460</td><td>2.2</td><td>60</td><td>1.7</td></tr></tbody></table>

<footnote><sup>a</sup>Not evaluated from the rise time but from the difference between the fluorescence lifetime of P5 in the presence and absence of PC71BM.</footnote>

<footnote><sup>b</sup>Shorter than the IRF.</footnote>

<footnote><sup>c</sup>Not evaluated.</footnote>
<table><caption>TABLE 2 | The photovoltaic parameters of binary and ternary OSCs under 100 mW·cm⁻² AM 1.5 G.</caption><thead><tr><th>Active layers</th><th>J<sub>SC</sub>, mA·cm<sup>-2</sup></th><th>V<sub>OC</sub>, V</th><th>FF</th><th>PCE, %</th></tr></thead><tbody><tr><td>P5:PC<sub>71</sub>BM<sup>a</sup><br>(1.0:1.4)</td><td>17.42 (17.23 ± 0.21)<sup>b</sup></td><td>0.86 (0.852 ± 0.007)<sup>b</sup></td><td>0.646 (0.639 ± 0.006)<sup>b</sup></td><td>9.68 (9.46 ± 0.21)<sup>b</sup></td></tr><tr><td>P5:Y6<sup>a</sup><br>(1.0:1.2)</td><td>23.42 (23.18 ± 0.25)<sup>b</sup></td><td>0.93 (0.923 ± 0.006)<sup>b</sup></td><td>0.690 (0.681 ± 0.008)<sup>b</sup></td><td>15.03 (14.81 ± 0.24)<sup>b</sup></td></tr><tr><td>P5:PC<sub>71</sub>BM:Y6<br>(1.0:0.2:1.0)</td><td>24.98 (24.81 ± 0.16)<sup>b</sup></td><td>0.89 (0.884 ± 0.005)<sup>b</sup></td><td>0.730 (0.723 ± 0.006)<sup>b</sup></td><td>16.23 (16.04 ± 0.19)<sup>b</sup></td></tr></tbody></table>

<figure><img src="image_6.png" /><figcaption>FIGURE 4 | (a) Current–voltage (J–V) characteristics under illumination (AM1.5. 100 mW·cm⁻²) and (b) EQE spectra of the binary P5:Y6 (1:1.2) and the ternary P5:PC71BM:Y6 (1:0.2:1) OSCs.</figcaption></figure>

calculated from eight devices, which is higher than average PCE for binary counterparts 9.46% for P5:PC71BM (1:1.4) [28] and 14.81% for P5:Y6 (1:1.2) [28] (Table 2). The stability of the optimized active layers P5:Y6 (1:1.2) and P5:PC71BM:Y6 (1:0.2:1.0) has been examined. The T80 (time at which the device retains 80% of the initial PCE) value for binary and ternary was around 415 and 648 h, respectively (Figure S13, SI). The enhanced stability of the ternary device compared to its binary counterpart is likely due to the improved blend morphology of the ternary active layer, which reduces charge recombination. This consequently reduces the buildup of trapped charge carriers, a common factor for the degradation of the device. The V<sub>OC</sub> of TOSC (0.89 V) is very similar to those of P5:PC71BM (0.86 V) and P5:Y6 (0.93 V) solar cells. It was confirmed with similar energy level of the frontier MOs determined from CV measurements carried out on the films of the binary P5:Y6 (1:1.2) and ternary blends P5:PC71BM:Y6 (1:0.2:1.0) (Figures S15, S16 and table S3, SI). The PCE enhancement of the ternary system is attributed to simultaneously enhanced J<sub>SC</sub> going from 23.42 to 24.98 mA·cm⁻² and FF going from 0.690 to 0.730 for binary and ternary active layer, respectively. Since the J<sub>SC</sub> of the OSC depends upon the light-harvesting ability of the active layer. The absorption spectra (Figure 1b, S7 and S8, SI) indicate that PC71BM exhibits a strong absorption band below 550 nm, where both P5 and Y6 exhibit low-intensity absorption bands. This, the incorporation of PC71BM in the P5:Y6 host binary active layer may improve the light-harvesting efficiency of the ternary active in 300–500 nm region with complementarity absorption of

PC71BM in wavelengths range below 550 nm, thereby enhancing the J<sub>SC</sub>.

The EQE spectra for the binary and ternary active layers have been recorded to support the enhancement of J<sub>SC</sub> in the TOSC with respect to the binary OSC (Figure 4b). The EQE values of the ternary OSC are significantly higher than that of the binary counterpart in the wavelength region of 300–600 nm, where the PC71BM has a high absorption band, indicating that the light-harvesting efficiency has been increased with the incorporation of PC71BM, which explains the increase of J<sub>SC</sub>. The J<sub>SC</sub> value estimated from the integration of EQE spectra is about 24.62 mA·cm⁻², which is very close to the value of 24.98 mA·cm⁻² obtained from the J–V characteristics under illumination (Table 2). The energy loss in the optimized OSCs based on P5 is estimated from the expression: E<sub>loss</sub> = E<sub>g</sub> – qV<sub>OC</sub>, where E<sub>g</sub> is the bandgap energy estimated from the onset of EQE spectra of the devices. The value of E<sub>loss</sub> for the binary and ternary devices is almost the same, about 0.45 and 0.49 eV, respectively, which agrees with the observed values of V<sub>OC</sub>. The maximum exciton generation rate (G<sub>max</sub>), exciton dissociation efficiency (η<sub>diss</sub>), charge collection efficiency (η<sub>coll</sub>), charge transport, and recombination dynamics play an important role in the determination of J<sub>SC</sub> and FF of the OSCs. The values of G<sub>max</sub>, η<sub>diss</sub>, and η<sub>coll</sub> were estimated from the dependence of the photocurrent density (J<sub>ph</sub>) with effective voltage (V<sub>eff</sub>) [50, 51]. The quasilinear increase of J<sub>ph</sub> with V<sub>eff</sub> before reaching the saturation of photocurrent density (J<sub>sat</sub>), where it is independent to V<sub>eff</sub> (Figure S14, SI), indicates that the photocurrent only depends

<footnote>aResults from reference 28.</footnote>

<footnote>bAverage of eight devices.</footnote>
upon the light-harvesting efficiency of the active layer used in the OSC. The $G_{max}$ can be estimated as $G_{max} = J_{phsat}/qL$, where L is the thickness of the active layer and q is the elementary charge. The value of $G_{max}$ for the ternary layer is larger than that of the binary counterpart. The largest value of $G_{max}$ is $1.53 \times 10^{28} m^{-3} s^{-1}$ for the TOSC with respect to the binary active layer P5:Y6 ($1.46 \times 10^{28} m^{-3} s^{-1}$). The exciton dissociation probability ($P_{diss}$) and charge collection probability ($P_{coll}$) are respectively estimated from the ratio $J_{ph}/J_{sat}$ under short circuit and maximum power point conditions. Both the $P_{diss}$ and $P_{coll}$ values are larger for the TOSC (0.988 and 0.812) than that of the binary one (0.967 and 0.793), indicating that the excitons are more efficiently dissociated into free charge carriers and subsequently collected by the electrodes of the TOSCs. In space charge limited current measurements (SCLC) model, the charge transport dynamics in the devices were investigated by measuring the dark J-V characteristics of electron-only and hole-only devices and fitting them with SCLC model (Figure 5a,b).

The electron/hole mobilities ($\mu_e/\mu_h$) of the ternary and binary active layer films are $3.36 \times 10^{-4} cm^2 V^{-1} s^{-1}/3.05 \times 10^{-4} cm^2 V^{-1} s^{-1}$ and $3.17 \times 10^{-4} cm^2 V^{-1} s^{-1}/2.52 \times 10^{-4} cm^2 V^{-1} s^{-1}$ with $\mu_e/\mu_h$ ratios of 1.10 and 1.26, respectively (Table S2, SI). The larger mobility and more balanced $\mu_e/\mu_h$ of the ternary device explain the enhanced value of FF of the TOSC (0.730) with respect to the binary OSC (0.690, P5:Y6 and 0.646, P5:PC71BM).

The charge recombination properties of OSCs were investigated by examining the transient photovoltage (TPV, Figure 6a) and transient photocurrent (TPC, Figure 6b) [52, 53]. The power-law relationship between $J_{SC}$ and illumination intensity ($P_{in}$) is shown in Figure 7a,b, where $J_{SC}$ is proportional to ($P_{in}$)$^\alpha$.

The degree of bimolecular recombination is estimated by the value of the exponent factor $\alpha$. The relationship is simply linear when the value of $\alpha$ is close to 1. The value of 0.982 of the TOSC is closer to 1 than that of the binary counterpart (0.971). Hence, the ternary device experiences less bimolecular recombination. The relationship between $V_{OC}$ and $P_{in}$ is presented in Figure 7b and provides information on the bimolecular and trap-assisted recombination. The slope of the fitted line of $V_{OC}$ versus ln ($P_{in}$) should be 1kT/q if the bimolecular recombination dominates in the device, while the trap-assisted recombination mechanism dominates if the slope is 2kT/q. The ternary device exhibits a smaller slope (1.21) as compared to the binary counterpart (1.29), thus indicating less trap-assisted recombination. To gain insight into the charge extraction capability and charge carrier lifetimes, TPC and TPV measurements were conducted. As shown in Figure 6b, the TPC shows that the charge extraction time of the ternary device is 0.854 µs, which is shorter than that of the binary counterpart (1.056 µs), indicating efficient charge carrier extraction in the ternary device. As shown in Figure 6a, the TPV measurements show the carrier lifetimes were 5.25 and

<figure><img src="image_7.png" /><figcaption>**FIGURE 5** | Dark J-V characteristics for (a) electron-only and (b) hole-only devices and their fitting with SCLC model to estimate electron and hole mobilities in P5: Y6 (1:1.2) and P5:PC71BM:Y6 (1:0.2:1) films.</figcaption></figure>

<figure><img src="image_8.png" /><figcaption>**FIGURE 6** | (a) TPV and (b) TPC curves for P5:Y6 (1:1.2) and P5:PC71BM:Y6 (1:0.2:1).</figcaption></figure>
<figure><img src="image_9.png" /><figcaption>FIGURE 7 | Variation of (a) $J_{SC}$ and (b) $V_{OC}$ with $P_{in}$ for P5:Y6 (1:1.2) and P5:PC$_{71}$BM:Y6 (1:0.2:1).</figcaption></figure>

8.56 µs for binary and ternary devices, respectively. The longer charge carrier lifetime in the ternary device may also confirm the suppression of recombination processes.

## 2.5 | Morphology Characterization

The microstructure of each film (P5, binary P5:PC$_{71}$BM, P5:Y6, and ternary blends P5:PC$_{71}$M:Y6) has been investigated by grazing incidence X-ray diffraction (GIXRD). XRD patterns showed the absence of diffraction peaks (Figures S17–20, SI). Despite a high value of the mass attenuation coefficient of Pt [54]. It was checked that for the P5 film, the attenuation of the X-ray beam intensity is ≤30% under the experimental conditions (angle of incidence of 0.2°, film thickness of 140 nm, Cu Kα radiation). Since the other films contain a lower mass proportion of Pt, we can assume that the absence of diffraction peaks is not linked to Pt absorption but is due to the amorphous nature of the material. It is in agreement with differential scanning calorimetry (DSC) measurement carried out on ternary active layer that evidences the absence of crystallinity of the material (Figure S21, SI). This result is similar to other types of [Pt]-polyyne oligomers prepared in our group [26–28] and is attributed to the steric hindrance induced by phosphine ligands linked to the Pt(II) complexes, which are detrimental for the regular aggregation of chains. Hence, the topography and roughness of pristine P5, binary P5:PC$_{71}$BM (1:1.4), P5:Y6 (1:1.2) and the ternary P5:PC$_{71}$BM:Y6 (1:0.2:1) films have been characterized using AFM. All the films were prepared with the donor P5 having the same acceptor weight ratio under identical conditions than that of the active layer of binary and ternary OSCs studied. The AFM phase images depicted in Figure 8 show the presence of fibers when P5 is blended with Y6 (P5:Y6 (1:1.4) and P5:PC$_{71}$BM:Y6 (1:0.2:1)). In contrast, no fiber was evidenced in pristine P5 and P5:PC$_{71}$BM films (without Y6). The absence of fiber in the film composed of only Y6 was checked.

HR-TEM images confirmed these observations with the absence of fiber in P5 and the presence of fibers in the ternary blend with a length ranging from 500 nm to one micrometer and diameter of 10–20 nm (Figure S22, SI). Energy-dispersive X-ray spectrometry (EDXS) spectrum displays the presence of elements in good agreement with the composition of the material, like platinum,

phosphorus, sulfur, carbon, and oxygen (Figure S23, SI). Diffraction pattern obtained from the selected area electron diffraction (SAED) performed on the fibers disclosed diffuse halos, which confirmed the amorphous nature of the material (Figure S24, SI). As fiber formation was exclusively observed upon the combination of P5 and Y6, it can be postulated that the fibers result from a specific interaction between these components (probably by π-π stacking), which could subsequently induce an orientation of the P5 oligomers by steric hindrance. The lack of sufficient crystallinity precludes an accurate structural determination of the fibers, which warrants further investigation. The formation of fibers may explain the enhanced performance of the Y6-containing binary and ternary OSCs, reaching PCE values of 14.8% and 16.0%, respectively, compared to 9.4% for P5:PC$_{71}$BM (1:1.4) [28]. Regarding the exciton diffusion length of 10–20 nm, the low diameter of the fibers promotes short migration length to D/A interface for their dissociation. P5:PC$_{71}$BM (1:1.4) film exhibits almost spherical shape structures confirmed with AFM height images (Figure S25, SI). It may be due to the tendency of PC$_{71}$BM to form clusters, therefore creating well-defined nanodomains [38, 55, 56] identified with strong contrast in AFM images (Figure S25, SI). It is in agreement with the reported investigation [55]. The roughness of P5, binary P5:PC$_{71}$BM (1:1.4), P5:Y6 (1:1.2), and the ternary P5:PC$_{71}$BM:Y6 (1:0.2:1) films have been analyzed from AFM height images (Figures S25 and S26, SI). It is clearly higher for P5:Y6 (8.18 mm) and P5:PC$_{71}$BM:Y6 films (8.39 mm). This could be explained by the presence of previously evidenced fibers. As a conclusion, using Y6 as an acceptor helps the nanostructuration of P5 in the form of nanofibers, which is a key parameter. Moreover, its miscibility with PC$_{71}$BM allows beneficiating from PC$_{71}$BM ability to broaden absorption range and to optimize the charge transfer [56], which explains why the PCE of the ternary P5:PC$_{71}$BM:Y6 (1:0.2:1) is the highest performance for [Pt]-containing polyyne oligomers and small molecules to date. In future investigations, different solution processing could be applied to the blends, such as hot spinning-coating process [57] or adding halogenated solvents for regulating the aggregation of NFA and improving the compatibility of the components [58]. The performances could be assessed regarding the type of morphology generated, such as obtaining a smoother active layer or increasing the number of fibers [58].
<figure><img src="image_10.png" /><figcaption>FIGURE 8 | AFM phase images of films of (a) P5, (b) P5:PC71BM (1:1.4), (c) P5:Y6 (1:1.2), and (d) P5:PC71BM:Y6 (1:0.2:1).</figcaption></figure>

3 | Conclusion

The preparation of a TOSC P5:PC71BM:Y6 composed of an electron donor 3,4-ethylenedioxythiophene (EDOT)/ diketopyrrolopyrrole (DPP)-containing [Pt] polyyne oligomer P5 [28] with the acceptors PC71BM and Y6 yields to a significant increase of the PCE from 14.8% to 16.0% in comparison to the reported binary OSC P5:Y6 [28]. This work reports an improvement of the synthetic route of ligand L5, which enables the preparation of larger quantities of P5. It was required for the preparation of several OSC devices by varying weight ratio of P5, PC71BM, and Y6 in the ternary active layer. The TOCS P5:PC71BM:Y6 (1:0.2:1) exhibits the best photovoltaic performances with higher average PCE of 16.0% (JSC = 24.98 mA·cm⁻², VOC of 0.89 V, and FF of 0.73) and a highest value of 16.2% with respect of two binary P5:PC71BM (1:1.4) (JSC = 17.42 mA·cm⁻², VOC of 0.86 V, and FF of 0.65) and P5:Y6 (1:1.2) (JSC = 23.42 mA·cm⁻², VOC of 0.93 V, and FF of 0.69) [28]. The photophysical investigations of the binary and ternary active layers highlight the impact of PC71BM on the electron transfer and the recombination processes. Upon electronic transfer from the electron donor to acceptors in the TOSC, three processes take place 1) P5*:PC71BM:Y6 → P5⁺*:PC71BM⁻*:Y6, 2) P5*:PC71BM:Y6 → P5⁺*:PC71BM:Y6⁻, and 3) P5⁺*:PC71BM⁻:Y6 → P5⁺*:PC71BM:Y6⁻. Depending on the process, the incorporation of PC71BM speeds up rise time for electron transfer and slows down the recombination times. The incorporation of PC71BM promotes exciton dissociation into free charges. The full study of optoelectronic properties of the TOSC P5:PC71BM:Y6 compared to the binary OSCs [28] P5:PC71BM and P5:Y6 highlights the optimization of light-harvesting

properties and exciton dissociation with the reduction of the recombination process in the TOCS, which supports the enhancement of PCEs. The incorporation of PC71BM in the blend P5:Y6 yields to an increase in absorption intensity of the TOCS in the range of 300–900 nm, leading to larger values of EQE and JSC, thanks to the complementarity of absorption between the three components. The faster mobility and more balanced μe/μh in the TOCS explain the larger value of FF for TOSC (0.730) with respect to the binary OSC (0.690, P5:Y6 and 0.646, P5:PC71BM). This TOSC exhibits maximization of excitons dissociation and reduction of electron-hole recombination with respect to the binary OSC. These results are in line with the presence of fibers in Y6-containing active layers observed in AFM and HR-TEM images. This work reports the first preparation of TOSC composed of [Pt(II)] polyyne oligomers as electron donor with acceptors. For the first time, it shows the presence of fibers in the active layer composed of [Pt(II)] polyyne oligomers when Y6 is blended. The increase of the average PCE to 16% of the ternary P5:PC71BM:Y6 (1:0.2:1) is explained by the assistance of Y6 for the nanostructuration of the active layer and the role of PC71BM to shorten electron transfer with its reported ability to form clusters in the blend [55]. This work reports the highest performance for [Pt(II)] polyynes oligomers and small molecules to date.

Acknowledgments

The authors warmly thank the French "ministère de l'enseignement supérieur de la recherche et de l'innovation", also Normandie region and LabEx Synorg (ANR-11-LABX-0029), which funded Abdel-Aziz
Wayzani Ph.D. The authors thank Normandie Université, UNICAEN, ENSICAEN, CNRS, INC3M, ANR, EUR XL-Chem, and LabEx EMC3 (ANR-10-LABX-09-01) for supporting our research activities. Julie Hardouin from PBS laboratory and PISSARO is thanked for the mass spectrometry analysis. P.D.H. acknowledges NSERC, the Natural Sciences and Engineering Research Council of Canada, for financial support. G.D.S. is thankful to the Department of Science and Technology for financial support Project No: DST/TMD/SERI/D05 (G). C.S. and F.M. thank the Platform MACLE - CVL, which was cofunded by the European Union and Centre-Val de Loire Region (FEDER). Corinne Bouillot is thanked for the TEM analysis

## Funding

This study was supported by Synorg LabEx (Grant ANR-11-LABX-0029), Région Normandie, Natural Sciences and Engineering Research Council of Canada, Conseil Régional du Centre-Val de Loire, the European Union, and Department of Science and Technology.

## Conflicts of Interest

The authors declare no conflicts of interest.

## Data Availability Statement

The data that support the findings of this study are available in the supplementary material of this article.

## References

1. G. Zhang, F. R. Lin, F. Qi, et al., "Renewed Prospects for Organic Photovoltaics," *Chemical Reviews* 122 (2022): 14180, https://doi.org/10.1021/acs.chemrev.1c00955.

2. C. Yan, J. Qin, Y. Wang, G. Li, and P. Cheng, "Emerging Strategies toward Mechanically Robust Organic Photovoltaics: Focus on Active Layer," *Advanced Energy Materials* 12 (2022): 2201087, https://doi.org/10.1002/aemn.202201087.

3. J. Yi, G. Zhang, H. Yu, and H. Yan, "Advantages, Challenges and Molecular Design of Different Material Types Used in Organic Solar Cells," *Nature Reviews Materials* 9 (2024): 46, https://doi.org/10.1038/s41578-023-00618-1.

4. P. Ding, D. Yang, S. Yang, and Z. Ge, "Stability of Organic Solar Cells: Toward Commercial Applications," *Chemical Society Reviews* 53 (2024): 2350, https://doi.org/10.1039/D3CS00492A.

5. Z. Hu, J. Wang, X. Ma, et al., "A Critical Review on Semitransparent Organic Solar Cells," *Nano Energy* 78 (2020): 105376, https://doi.org/10.1016/j.nanoen.2020.105376.

6. J. Fu, Q. Yang, P. Huang, et al., "Rational Molecular and Device Design Enables Organic Solar Cells Approaching 20% Efficiency," *Nature Communications* 15 (2024): 1830, https://doi.org/10.1038/s41467-024-46022-3.

7. Z. Chen, J. Zhu, D. Yang, et al., "Isomerization Strategy on a Non-Fullerene Guest Acceptor for Stable Organic Solar Cells with over 19% Efficiency," *Energy & Environmental Science* 16 (2023): 3119, https://doi.org/10.1039/D3EE01164J.

8. Z. Gan, L. Wang, J. Cai, et al., "Electrostatic Force Promoted Intermolecular Stacking of Polymer Donors toward 19.4% Efficiency Binary Organic Solar Cells," *Nature Communications* 14 (2023): 6297, https://doi.org/10.1038/s41467-023-42071-2.

9. H. Lu, W. Liu, G. Ran, et al., "High-Pressure Fabrication of Binary Organic Solar Cells with High Molecular Weight D18 Yields Record 19.65% Efficiency," *Angewandte Chemie International Edition* 62 (2023): e202314420, https://doi.org/10.1002/anie.202314420.

10. C.-M. Oh, S. Park, J. Lee, et al., "Enhanced Charge Separation by Interchain Hole Delocalization in Nonfullerene Acceptor-Based Bulk

Heterojunction Materials," *Carbon Energy* 5 (2023): e302, https://doi.org/10.1002/cey2.302.

11. H. Yu, Y. Wang, X. Zou, et al., "Effects of Halogenation of Small-Molecule and Polymeric Acceptors for Efficient Organic Solar Cells," *Advanced Functional Materials* 33 (2023): 2300712, https://doi.org/10.1002/adfm.202300712.

12. J. Shao, M. Li, G. Chen, et al., "Developing a Fluorinated Benzothiadiazole-Based Polymer Donor as Guest to Construct High-Performance Ternary Solar Cells," *ChemSusChem* 18 (2025): e202402226, https://doi.org/10.1002/cssc.202402226.

13. Y. Li, Z. Chen, X. Yan, et al., "Molecular Packing Tuning via Chlorinated End Group Enables Efficient Binary Organic Solar Cells over 18.5%," *Carbon Energy* 6 (2024): e439, https://doi.org/10.1002/cey2.439.

14. C. Yang, C. Zhao, Y. Sun, et al., "Optical Management in Organic Photovoltaic Devices," *Carbon Energy* 3, no. 1 (2021): 4, https://doi.org/10.1002/cey2.97.

15. A. Mishra, S. Mahalik, and A. Mishra, "Influence of Alkyl Chain Length on Solar Cell Performance of Molecular Organic Semiconductors: A Review," *Chemical Communications* 61 (2025): 3649, https://doi.org/10.1039/D9CC06017B.

16. B. Fan, H. Gao, and A. K.-Y. Jen, "Biaxially Conjugated Materials for Organic Solar Cells," *ACS Nano* 18 (2024): 136, https://doi.org/10.1021/acsnano.3c11193.

17. X. Ji, T. Wang, Q. Fu, et al., "Deciphering the Effects of Molecular Dipole Moments on the Photovoltaic Performance of Organic Solar Cells," *Macromolecular Rapid Communications* 44 (2023): 2300213, https://doi.org/10.1002/marc.202300213.

18. L. Zhu, M. Zhang, J. Xu, et al., "Single-Junction Organic Solar Cells with over 19% Efficiency Enabled by a Refined Double-Fibril Network Morphology," *Nature Materials* 21 (2022): 656, https://doi.org/10.1038/s41563-022-01244-y.

19. J. Zhou, L. Wang, C. Liu, et al., "Tuning of the Polymeric Nanofibril Geometry via Side-Chain Interaction toward 20.1% Efficiency of Organic Solar Cells," *Journal of the American Chemical Society* 146 (2024): 34998, https://doi.org/10.1021/jacs.4c15266.

20. C. Chen, L. Wang, W. Xia, et al., "Molecular Interaction Induced Dual Fibrils towards Organic Solar Cells with Certified Efficiency over 20%," *Nature Communications* 15 (2024): 6865, https://doi.org/10.1038/s41467-024-51359-w.

21. Q. Lv, R. Yu, R. Shi, et al., "Recent Progress in Organic-Metal Complexes for Organic Photovoltaic Applications," *Materials Chemistry Frontiers* 7 (2023): 5063, https://doi.org/10.1039/D3QM00603D.

22. A. Haque, R. A. Al-BalushiIdris, J. Al-Busaidi, et al., "Rise of Conjugated Poly-Ynes and Poly(Metalla-Ynes): From Design Through Synthesis to Structure-Property Relationships and Applications," *Chemical Reviews* 118, no. 18 (2018): 8474, https://doi.org/10.1021/acs.chemrev.8b00022.

23. R. A. Al-Balushi, A. Haque, I. J. Al-Busaidi, et al., "Heterometal Grafted Metalla-Ynes and Poly(metalla-Ynes): A Review on Structure-Property Relationships and Applications," *Polymers* 13 (2021): 3654, https://doi.org/10.3390/polym13213654.

24. X. Xu, K. Feng, Z. Bi, et al., "Single-Junction Polymer Solar Cells with 16.35% Efficiency Enabled by a Platinum(II) Complexation Strategy," *Advanced Materials* 31 (2019): 1901872, https://doi.org/10.1002/adma.201901872.

25. A. Ruiz-Carretero, Y. Atoini, T. Han, et al., "Charge Transport Enhancement in Supramolecular Oligothiophene Assemblies Using Pt(ii) Centers as a Guide," *Journal of Materials Chemistry A* 7 (2019): 16777, https://doi.org/10.1039/C9TA04364K.

26. M. Nos, G. Marineau-Plante, D. Gao, et al., "A Bis(diketopyrrolopyrrole) Dimer-Containing Ligand in Platinum(ii) Polyyne Oligomers Exhibiting Ultrafast Photoinduced Electron Transfer
with PCBM and Solar Cell Properties," Journal of Materials Chemistry C 8 (2020): 2363, https://doi.org/10.1039/C9TC03487K.

27. G. Marineau-Plante, M. Nos, D. Gao, et al., "Effect of Mesogenic Side Groups on the Redox, Photophysical, and Solar Cell Properties of Diketopyrrolopyrrole-Trans-Bis(diphosphine)diethynylplatinum(II) Polymers," ACS Applied Polymer Materials 3 (2021): 1087, https://doi.org/10.1021/acsapm.0c01325.

28. M. Qassab, J.-F. Lohier, G. Marineau-Plante, et al., "Role of 3,4-Ethylenedioxythiophene in the Enhancement of Optical and Charge Transport Properties of Low Band Gap Diketopyrrolopyrrole-Containing Metallooligomers Designed for Organic Solar Cells," ACS Applied Energy Materials 6 (2023): 12452, https://doi.org/10.1021/acsaem.3c02337.

29. J. Zhou, X. Zhou, H. Jia, et al., "20.0% Efficiency of Ternary Organic Solar Cells Enabled by a Novel Wide Band Gap Polymer Guest Donor," Energy & Environmental Science 18 (2025): 3341, https://doi.org/10.1039/D4EE05848H.

30. D. Zhou, W. You, H. Xu, et al., "Recent Progress in Ternary Organic Solar Cells Based on Solution-Processed Non-Fullerene Acceptors," Journal of Materials Chemistry A 8 (2020): 23096, https://doi.org/10.1039/D0TA08559F.

31. K. A. Nirmal, T. D. Dongale, S. S. Sutar, A. C. Khot, and T. G. Kim, "Machine Learning Empowers Efficient Design of Ternary Organic Solar Cells with PM6 Donor," Journal of Energy Chemistry 100 (2025): 337, https://doi.org/10.1016/j.jechem.2024.08.052.

32. S. Cheng, J. Qiao, P. Lu, W. Qin, and X. Hao, "Controllable Exciton Diffusion Length and Ultrafast Charge Generation in Ternary Organic Solar Cells," Chinese Journal of Chemistry 42 (2024): 1275, https://doi.org/10.1002/cjoc.202300741.

33. J. Liu, X. Liu, J. Xin, et al., "Dual Function of the Third Component in Ternary Organic Solar Cells: Broaden the Spectrum and Optimize the Morphology," Small 20 (2024): 2308863, https://doi.org/10.1002/smll.202308863.

34. H. Zhou, C. Liu, S. Liu, et al., "PC71BM as Morphology Regulator for Highly Efficient Ternary Organic Solar Cells with Bulk Heterojunction or Layer-by-Layer Configuration," Small 20 (2024): 2308216, https://doi.org/10.1002/smll.202308216.

35. H. Wang, S. Wu, D. Yang, et al., "19.3% Efficiency Ternary Organic Solar Cells Enabled by the Alkyl Side-Chain Effect of Guest Non-Fullerene Acceptors," Science China Chemistry 67 (2024): 2686, https://doi.org/10.1007/s11426-024-2011-3.

36. X. Liu, Z. Zhang, C. Wang, et al., "A Pyrene-Fused Dimerized Acceptor for Ternary Organic Solar Cells with 19% Efficiency and High Thermal Stability," Angewandte Chemie International Edition 63 (2024): e202316039, https://doi.org/10.1002/anie.202316039.

37. M.-A. Pan, T.-K. Lau, Y. Tang, et al., "16.7%-Efficiency Ternary Blended Organic Photovoltaic Cells with PCBM as the Acceptor Additive to Increase the Open-Circuit Voltage and Phase Purity," Journal of Materials Chemistry A 7 (2019): 20713, https://doi.org/10.1039/C9TA06929A.

38. A. Schlachter, G. Marineau-Plante, P. D. Harvey, A. Agrawal, and G. D. Sharma, "Efficient Ternary Bulk Heterojunction Organic Solar Cells Using a Low-Cost Nonfullerene Acceptor," Journal of Materials Chemistry C 10 (2022): 4372, https://doi.org/10.1039/D1TC05653K.

39. L. Hrostea, A. Oajdea, and L. Leontie, "Impact of PCBM as a Third Component on Optical and Electrical Properties in Ternary Organic Blends," Polymers 16 (2024): 1324, https://doi.org/10.3390/polym16101324.

40. C. Wang, C. J. Mueller, E. Gann, et al., "EDOT-diketopyrrolopyrrole Copolymers for Polymer Solar Cells," Journal of Materials Chemistry A 4 (2016): 3477, https://doi.org/10.1039/C5TA10078J.

41. L. Pan, T. Liu, J. Wang, et al., "Efficient Organic Ternary Solar Cells Employing Narrow Band Gap Diketopyrrolopyrrole Polymers and

Nonfullerene Acceptors," Chemistry of Materials 32 (2020): 7309, https://doi.org/10.1021/acs.chemmater.0c02133.

42. X. Song, N. Gasparini, M. M. Nahid, et al., "Efficient DPP Donor and Nonfullerene Acceptor Organic Solar Cells with High Photon-to-Current Ratio and Low Energetic Loss," Advanced Functional Materials 29 (2019): 1902441, https://doi.org/10.1002/adfm.201902441.

43. X. Zou, G. Wen, R. Hu, et al., "Insight into the Excitation States of Small Molecular Semiconductor Y6," Molecules 25 (2020): 4118, https://doi.org/10.3390/molecules25184118.

44. S. Albert-Seifried, D.-H. Ko, S. Hüttner, et al., "Efficiency Limitations in a Low Band-Gap Diketopyrrolopyrrole-Based Polymer Solar Cell," Physical Chemistry Chemical Physics 16 (2014): 6743, https://doi.org/10.1039/C4CP00485J.

45. X. Shen, S. Yang, K. Niu, et al., "The Role of Isomeric Alkyl Chains of Polymer Donors on Charge-Transfer Processes in Non-Fullerene Organic Photovoltaics: A Theoretical Investigation," Journal of Nanoparticle Research 26 (2024): 86, https://doi.org/10.1007/s11051-024-05997-2.

46. D. Osella, R. Gobetto, C. Nervi, et al., "Synthesis and Characterisation of Bis(ferrocenylethynyl) Complexes of Platinum (II) A Re-Investigation of Their Electrochemical Behaviour," Inorganic Chemistry Communications 1 (1998): 239, https://doi.org/10.1016/S1387-7003(98)00064-1.

47. W.-Y. Wong, L. Liu, S.-Y. Poon, et al., "Harvesting of Organic Triplet Emissions in Metal Diynes and Polynes of Group 10–12 Transition Elements Containing the Conjugation-Interrupting Diphenylfluorene Unit," Macromolecules 37 (2004): 4496, https://doi.org/10.1021/ma049773o.

48. G. A. Farrow, M. Quick, S. A. Kovalenko, et al., "On the Intersystem Crossing Rate in a Platinum(ii) Donor–bridge–acceptor Triad," Physical Chemistry Chemical Physics 23 (2021): 21652, https://doi.org/10.1039/D1CP03471E.

49. R. Datt, A. Suman, A. Bagui, et al., "Effectiveness of Solvent Vapor Annealing over Thermal Annealing on the Photovoltaic Performance of Non-Fullerene Acceptor Based BHJ Solar Cells," Scientific Reports 9 (2019): 8529, https://doi.org/10.1038/s41598-019-44232-0.

50. Y. Chen, T. Liu, H. Hu, et al., "Modulation of End Groups for Low-Bandgap Nonfullerene Acceptors Enabling High-Performance Organic Solar Cells," Advanced Energy Materials 8 (2018): 1801203, https://doi.org/10.1002/aenm.201801203.

51. N. Gasparini, M. Salvador, S. Strohm, et al., "Burn-in Free Nonfullerene-Based Organic Solar Cells," Advanced Energy Materials 7 (2017): 1700770, https://doi.org/10.1002/aenm.201700770.

52. Y. Wei, Z. Chen, G. Lu, et al., "Binary Organic Solar Cells Breaking 19% via Manipulating the Vertical Component Distribution," Advanced Materials 34 (2022): 2204718, https://doi.org/10.1002/adma.202204718.

53. J. Ge, L. Hong, H. Ma, et al., "Asymmetric Substitution of End-Groups Triggers 16.34% Efficiency for All-Small-Molecule Organic Solar Cells," Advanced Materials 34 (2022): 2202752, https://doi.org/10.1002/adma.202202752.

54. J. H. Hubbell and S. M. Seltzer, "NIST Standard Reference Database 126. X-Ray Mass Attenuation Coefficients," Tables of X-ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients 1 keV to 20 MeV for Elements Z = 1 to 92 and 48 Additional Substances of Dosimetric Interest (No. PB-95-220 539/XAB; NISTIR-5632 (National Institute of Standards and Technology-PL, Ionizing Radiation Div., 1995), https://doi.org/10.18434/T4D01F.

55. V. Jovanov, N. Yumnam, A. Müller, M. Gruber, and V. Wagner, "Determining Material-Specific Morphology of Bulk-Heterojunction Organic Solar Cells Using AFM Phase Imaging," The Journal of Physical Chemistry C 121 (2017): 9173, https://doi.org/10.1021/acs.jpcc.7b01924.

56. X. Liu, S. Du, Z. Fu, et al., "Ternary solar cells via ternary polymer donors and third component PC71BM to optimize morphology with
13.15% efficiency,” *Solar Energy* 222 (2021): 18, https://doi.org/10.1016/j.solener.2021.05.011.

57. T. Huang, S. Geng, D. Wang, et al., “18.63% Efficiency of Ternary Organic Solar Cells Achieved via Nonhalogenated Solvent and Hot Spin-Coating Process,” *Advanced Functional Materials* 34 (2024): 2315825, https://doi.org/10.1002/adfm.202315825.

58. B. Ma, Y. Yan, M. Wu, et al., “Sustainable Solution Processing Toward High-Efficiency Organic Solar Cells: A Comprehensive Review of Materials, Strategies, and Applications,” *Advanced Functional Materials* 35 (2025): 2413814, https://doi.org/10.1002/adfm.202413814.

## Supporting Information

Additional supporting information can be found online in the Supporting Information Section. **Supporting Scheme S1:** Synthesis of the ligand **L5** after a Stille coupling reaction from stannic derivative **2b** and bis-brominated DPP **3**. **Supporting Fig. S1:** Transient absorption spectrometer apparatus (**Laser source:** Solstice (*Spectra-Physics*). Ti-Sapph re-generative laser producing pulses of 3.5 mJ of ~75 fs, centered at 795 nm at a 1 kHz maximum repetition rate; **Optical parametric amplifier:** OPA-800CF (*Spectra-Physics*). OPA with SHG, FHG and SFM spanning between 330-3100 nm; **Harmonics generator:** FK-800-100-M (*Eksma Optics*). To generate the SHG at 397 nm and the THG at 265 nm; **Delay stage:** VT-75-600 (*Micos USA*). Mechanical delay with a resolution of 0,4 µm and a range of 60 cm that gives ~8 ns of optical delay with two passes; **Pulse picker**, custom built by Axis Photonique Inc. Maximum repetition rate at 1MHz; **BOA**. Single prism compressor; **PCF:** FemtoWHITE 800 (*NKT Photonics*). Photonic crystal fiber to generate white pulses; **White light continuum**. Sapphire, CaF2 or YAG windows to probe from 330 nm to 1800 nm; **Spectrograph:** MS260i (*Newport*). Spectrograph with 3 gratings to cover the 160-2400 nm; **Camera:** custom built by Spectronic Devices Ltd. Dual channel line camera built with two S7030 CCDs (Hamamatsu) to simultaneously measure the probe and the reference spectra at 1 kHz; **Sample holder.** 1) 1–2 mm cuvette holder with a magnetic stirrer and a Peltier element to regulate the temperature between 260 to 350 K. 2) Cryostat for solid state samples with temperature control between ~12 to 350 K. **Supporting Fig. S1:** ¹H NMR (600 MHz) spectrum of **L5** in CDCl₃. **Supporting Fig. S2:** ¹³C NMR (150 MHz) spectrum of **L5** in CDCl₃. **Supporting Fig. S3:** ¹H NMR (600 MHz) spectrum of **P5** in CDCl₃. **Supporting Fig. S4:** ³¹P{¹H} NMR (243 MHz) spectrum of P5 in CDCl₃. **Supporting Fig. S5:** SEC chromatogram of [Pt]-oligomer **P5**. **Supporting Fig. S6:** Normalized absorption spectra of **L5** and **P5** in CH₃Cl₂ (solid line) and as a thin film of **P5** (dashed line). **Supporting Fig. S7:** Normanized absorption spectra of thin films for the three components **P5**, PC₇₁BM, Y6 and their corresponding blends. **Supporting Fig. S8:** Normalized absorption spectrum of the ternary blend of **P5**:PC₇₁BM:Y6 (1:1:1) as a thin film. **Supporting Fig. S9:** PL spectra of a) **P5**, PC₇₁BM and the binary **P5**:PC₇₁BM (1:1.4) b) **P5**, Y6 and the binary **P5**:Y6 (1:1.2) c) PL spectra of **P5**, PC₇₁BM, Y6 and the ternary **P5**:PC₇₁BM:Y6 (1:0.2:1). **Supporting Fig. S10:** Absorption spectrum of Y6 and PL spectrum of PC71BM on films. **Supporting Fig. S11:** Steady-state absorption (red), excitation (purple) and fluorescence (green) spectra of **P5**, PC₇₁BM, and Y6 in solution (top) and as thin films (bottom) at 293 K. **Supporting Fig. S12:** Time-dependent fs-TA spectra of the investigated compounds and blends in thin film. **Supporting Fig. S13:** Stability test of the OSCs based on optimized binary **P5**:Y6 and ternary **P5**:PC₇₁BM:Y6, without encapsulation and stored in ambient conditions. **Supporting Fig. S14:** Variation of the photocurrent density (Jph) with the effective voltage (Veff) for OSCs based on **P5**:Y6 (1:1.2) and **P5**:PC₇₁BM:Y6 (1:0.2:1) active layers. **Supporting Fig. S15:** CV of binary film **P5**:Y6 (1:1.2). The thin film was casted from a CHCl₃ solution onto a platinum disc working electrode (d = 5 mm), and the CVs were recorded in CH₃CN solution containing NBu4PF6, 10⁻¹ mol. L⁻¹ as supporting electrolyte (scan rate of 50 mV·s⁻¹). **Supporting Fig. S16:** CV of ternary film **P5**:PC₇₁BM: Y6 (1:0.2:1). The thin film was casted from a CHCl₃ solution onto a platinum disc working electrode (d = 5 mm), and the CVs were recorded in CH₃CN solution containing NBu4PF6, 10-1 mol. L⁻¹ as supporting electrolyte (scan rate of 50 mV·s⁻¹). **Supporting Fig. S17:** XRD patterns of **P5** film. **Supporting Fig. S18:** XRD patterns

of the binary **P5**: PC₇₁BM (1:1.4) film. **Supporting Fig. S19:** XRD patterns of the binary **P5**:Y6 (1:1.2) film. **Supporting Fig. S20:** XRD patterns of the ternary **P5**:PC₇₁BM:Y6 (1:0.2:1) film. **Supporting Fig. S21:** DSC curve of the ternary **P5**:PC₇₁BM:Y6 (1:0.2:1) film. **Supporting Fig. S22:** HR-TEM images (left) **P5** film and (right) the ternary **P5**: PC₇₁BM:Y6 (1:0.2:1) film. **Supporting Fig. S23:** Energy-dispersive X-ray spectroscopy (EDXS) spectrum of the ternary **P5**:PC₇₁BM:Y6 (1:0.2:1). **Supporting Fig. S24:** (a) HR-TEM image with the selected area with a diameter of ≈ 400nm (b) Selected Area Electron Diffraction (SAED) pattern performed on the selected area. **Supporting Fig. S25:** AFM height images of films of a) **P5** b) **P5**:PC₇₁BM (1:1.4), c) **P5**:Y6 (1:1.2), and d) **P5**:PC₇₁BM:Y6 (1:0.2:1). **Supporting Fig. S26:** AFM height images of **P5** film 1x1 µm (left) and 5x5 µm (right). **Supporting Table S1:** Photovoltaic parameters of TOSCs cast from chloroform solution without SVA treatment. **Supporting Table S2:** Values of electron and hole mobilities with the calculated ratio µc/µh. **Supporting Table S3:** Values of energy levels EHOMO and ELUMO determined from cyclic voltammetry.