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Intrinsically stretchable organic photovoltaic cells (OPVs) have garnered significant attention as crucial devices for powering next‐generation wearable electronics. Despite the rapid power conversion efficiency gains in champion OPVs, their brittle stretchability has failed to meet the demands of the Internet of Things era, severely hindering further development and practical applications. In this regard, a new dual‐donor polymer blending strategy is demonstrated for constructing intrinsically stretchable OPVs by designing a novel high‐molecular–weight conjugated polymer PM6‐HD. This PM6 derivative featuring long alkyl chains can reach a sufficiently high molecular weight and thus exhibits a high fracture strain exceeding 90%, which is ≈12 times higher than the benchmark PM6. Synergistic optimization of mechanical properties and photovoltaic performance in polymer:small molecule and all‐polymer systems constructed from the physical blends of PM6 and PM6‐HD is achieved. Crucially, the resulting intrinsically stretchable OPV demonstrates excellent stretchability and stability, with a record PCE80% strain of 50.3% and the efficiency retention of above 80% even after 1000 cycles of cyclic stretching at high strains. This work contributes to the advancement of intrinsically stretchable OPV technology and opens up new possibilities for its integration into wearable electronic devices. [ABSTRACT FROM AUTHOR]

Direct arylation polymerization (DArP) is a synthetic method for conjugated polymers; in DArP, organometallic functionalization steps are omitted and there are no toxic byproducts. As a result, it is considered a more sustainable alternative compared to conventional methods such as Stille polymerization. To explore the possibility of DArP‐based polymers as donor materials in organic solar cells (OSCs), a series of conjugated polymers based on the structure of PDCBT (poly[2,2''''‐bis[[(2‐butyloctyl)oxy]carbonyl][2,2':5',2'':5'',2'''‐quaterthiophene]‐5,5'''‐diyl]) are synthesized using DArP and Stille polymerization. By controlling the monomer concentration and reaction time in DArP, DArP‐5 with the highest Mn (21.9 kDa) can be obtained and its optoelectronic properties, electrochemical properties, and microscopic molecular ordering are comparable to those of Stille‐based PDCBT (Stille‐P). Analysis of the polymer structure indicates no structural defects such as crosslinking from undesired β‐coupling reactions in DArP‐5. Upon blending with the PC71BM acceptor molecule, an increase in the crystallite size of DArP‐5 is also observed. In OSC devices with a polymer:PC71BM bulk‐heterojunction photoactive layer, DArP‐5 demonstrates a comparable power conversion efficiency of 5.8% with that of Stille‐P (5.5%). These results prove that DArP is suitable for synthesizing PDCBT, and DArP‐based PDCBT can be used in OSCs as an alternative of Stille‐based one. [ABSTRACT FROM AUTHOR]

Impressive advancements in solution‐processed bulk heterojunction (BHJ) solar cells have been driven to a large extent by the rational design of conjugated polymers as photoactive donors. These achievements have been obtained without paying much attention to green metrics parameters (such as E factor) and to the increasing synthetic complexity (SC), which is a bottleneck for industrial scalability. In this context, a novel donor copolymer (PBDT3T) based on benzodithiophene and terthiophene building blocks with ester functionalities is synthesized. The 26‐fold‐reduced E factor for the benzodithiophene monomer synthesis and the SC index of 24 for PBDT3T, much lower compared with benchmark donor polymers, provide a hint for good scalability, sustainability, and low costs. PBDT3T features a relatively wide optical bandgap and a deep highest occupied molecular orbital (HOMO), meeting the requirements for suitable donor material in both fullerene and nonfullerene‐based solar cells. PBDT3T is studied in binary and ternary blend, using PC71BM and ITIC as acceptors. The best performances are obtained in the ternary blend devices, reaching power conversion efficiency (PCE) values of 7.14%. Trade‐off considerations between PCE and SC make PBDT3T promising on an industrial perspective.

[Display omitted] • Tailorable thiophenes are introduced into polymers symmetrically or asymmetrically. • The polymers bearing asymmetric π bridges overperform their symmetric counterparts. • Asymmetric π bridges engineering is confirmed to be a promising strategy for donors. In comparison with the common-used electron donor (D)-electron acceptor (A) type symmetric polymers with regular structures, their asymmetric counterparts have received much less attention and seldom been applied in polymer solar cells. Since the precise modulation of π bridge can significantly influence the photoelectric properties of D-A type polymers, π bridges of tailorable thiophenes are introduced into benzodithiophene (BDT)-benzodithiophene-4,8-dione (BDD) copolymers in both symmetric and asymmetric patterns. Together with the halogen substituent of fluorine or chlorine on BDT, four polymer donors are designed and synthesized. As expected, PTB2T-F and PTB2T-Cl with the asymmetric π bridges of thiophene and hexyl-bithiophene exhibit better planarity, stronger intermolecular interaction and higher hole mobility than P2TB2T-F and P2TB2T-Cl with the symmetric π bridges of hexyl-bithiophene. The more suitable phase separation and optimized nanomorphology is determined by the reasonable miscibility between asymmetric polymer and acceptor, which is evaluated by Flory-Huggins interaction, contributing to the extremely higher performance than that of symmetric counterpart. Moreover, paired with IT-4F as the acceptor, PTB2T-F affords better device performances than the reference BDT-BDD polymer PM6 with the symmetry π bridge of thiophene. These results demonstrate that the precise modulation of asymmetric π bridges is a promising strategy to construct high-efficiency D-A type polymer donors. [ABSTRACT FROM AUTHOR]

Nonfullerene organic solar cells (NFOSCs) have proven to have greater potential in terms of efficiency than fullerene‐based OSCs. However, the heterogeneity of nonfullerene acceptors (NFAs)‐based blend morphology is complex, making it difficult to understand, especially as its optimization requires that compatibility among the molecules be considered. Herein, P(Cl)(F = 0.5) is newly synthesized with a type of terpolymer to increase compatibility with NFAs relative to that of conventional polymers. As a result, the combination of P(Cl)(F = 0.5) with IDIC increases its power conversion efficiency (PCE) to 12.1%, compared with that of P(Cl):ITIC‐Th and P(F‐Cl):IT‐4F. However, during the shelf life stability of optimized devices without encapsulation, a rapid decrease in the efficiency of P(Cl)(F = 0.5):IDIC and P(F‐Cl):IT‐4F is observed; the PCEs of P(Cl) (F = 0.5):IDIC and P(F‐Cl):IT‐4F decrease to 24.1% and 43.5% of their initial values for up to 350 and 398 h, respectively. On the contrary, P(Cl):ITIC‐Th exhibits superior longterm air stability with a PCE decrease of −2% (for 317‐h) and 9% (for 2002‐h) compared with the initial PCE. To understand this phenomenon, the correlation between crystallinity and miscibility of blend films is systematically investigated. In short, the balanced crystallinity and miscibility of donor and acceptor induces a relatively more stable morphology. [ABSTRACT FROM AUTHOR]

Two novel polymer donors PBF-STTz and PBSiCl-STTz based on benzo [1,2- b :4,5- b ']dithiophene (BDT) and thiazolo[5,4- d ]thiazole (TTz) with alkythiol side chain and different heteroatoms (F, Cl, Si) modification were designed and synthesized. Both polymers show the similar and strong absorption within the range of 300 nm–650 nm. By incorporation the Cl atoms, Si alkyl chains and thioalkyl chains, the deeper HOMO level of PBSiCl-STTz was obtained to −5.59 eV. The PBSiCl-STTz:Y6-based device achieved an optimized power conversion efficiency (PCE) of 7.61%. While the device based on PBF-STTz:Y6 shows better PCE of 11.01% because of its better blend film morphology. In addition, in order to enhance the photovoltaic performance of device based on PBF-STTz, we fabricated devices using L8-BO as the acceptor and PBF-STTz as the donor. Due to better suppression of charge recombination probability, higher and more balanced hole and electron mobilities, as well as further improved blend film morphology, the PBF-STTz:L8-BO-based device achieved higher PCE of 11.52% with a boosted V oc and FF of 0.909 V and 66.25%, respectively. These results not only advance our understanding of the structure-performance relationships of BDT-TTz based donor polymers, but also provide a new avenue to design high-performance donor materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Significant progress has been made in nonfullerene small molecule acceptors (NF‐SMAs) that leads to a consistent increase of power conversion efficiency (PCE) of nonfullerene organic solar cells (NF‐OSCs). To achieve better compatibility with high‐performance NF‐SMAs, the direction of molecular design for donor polymers is toward wide bandgap (WBG), tailored properties, and preferentially ecofriendly processability for device fabrication. Here, a weak acceptor unit, methyl 2,5‐dibromo‐4‐fluorothiophene‐3‐carboxylate (FE‐T), is synthesized and copolymerized with benzo[1,2‐b:4,5‐b′]dithiophene (BDT) to afford a series of nonhalogenated solvent processable WBG polymers P1‐P3 with a distinct side chain on FE‐T. The incorporation of FE‐T leads to polymers with a deep highest occupied molecular orbital (HOMO) level of −5.60−5.70 eV, a complementary absorption to NF‐SMAs, and a planar molecular conformation. When combined with the narrow bandgap acceptor ITIC‐Th, the solar cell based on P1 with the shortest methyl chain on FE‐T achieves a PCE of 11.39% with a large Voc of 1.01 V and a Jsc of 17.89 mA cm−2. Moreover, a PCE of 12.11% is attained for ternary cells based on WBG P1, narrow bandgap PTB7‐Th, and acceptor IEICO‐4F. These results demonstrate that the new FE‐T is a highly promising acceptor unit to construct WBG polymers for efficient NF‐OSCs.

[Display omitted] • We constructed a new type of intrinsically stretchable active layer. • We synergistic optimized the mechanical and photovoltaic properties of OPV film. • We successfully predicted the changes in elastic modulus of the blend film. In recent years, the power conversion efficiency of all-polymer organic photovoltaic cells (OPVs) has surpassed 19%, reaching a level suitable for commercial applications. To meet the dual requirements of high efficiency and high stretchability for wearable applications, ternary blending strategies have been widely used to improve the tensile properties of all-polymer OPVs. However, up to now, synergistic optimization of both photovoltaic and mechanical properties has seldom been realized. Herein, we introduce a long-branched side chain-containing PM6-like donor polymer, PM6-OD, into a PM6:PY-IT blend to construct stretchable active layers for all-polymer OPVs. When the weight content of PM6-OD in the donor polymers is 20%, both the photovoltaic and mechanical properties of the ternary solar cell are maximized. The variation of the mechanical and photovoltaic properties with the PM6-OD content in the donor was analyzed through grazing-incidence X-ray scattering and thin-film mechanical measurements to gain a deeper understanding of the intrinsic relationship between blend microstructure and mechanical properties. In addition, we prove that the data points of elastic moduli match well with the Kerner-Davis model. This work provides new guidance for the construction of high-efficiency, stretchable OPVs and has a promoting effect on the application of OPVs in wearable/stretchable electronics. [ABSTRACT FROM AUTHOR]

Performance enhancement of polymer solar cells (PSCs) is achieved by expanding the absorption of the active layer of devices. To better match the spectrum of solar radiation, two polymers with different band gaps are used as the donor material to fabricate ternary polymer cells. Ternary blend PSCs exhibit an enhanced short-circuit current density and open-circuit voltage in comparison with the corresponding HD-PDFC-DTBT (HD)- and DT-PDPPTPT (DPP)-based binary polymer solar cells, respectively. Ternary PSCs show a power conversion efficiency (PCE) of 6.71%, surpassing the corresponding binary PSCs. This work demonstrates that the fabrication of ternary PSCs by using two polymers with complementary absorption is an effective way to improve the device performance. [ABSTRACT FROM AUTHOR]

Recently, perylene bisimides have been explored and developed as potential candidates for non-fullerene acceptors and power conversion efficiencies ( PCE s) exceeding 3% were realized in the non-fullerene polymer solar cells (NF-PSCs) featuring perylene bisimides as acceptors. Considering that only a few donor polymers like P3HT and PBDTTT-C-T were utilized in non-fullerene PSCs, screening donor polymers with well-matched energy levels, absorption spectrum as well as hole mobility in NF-PSCs will be the key to promote the current PCE s. Herein, four high performance donor polymers including PBDTTPD, PBDTTT-EFT, PDPP3T, PSBTBT were employed for the optimization of single bond-linked perylene bisimide (SDIPBI)-based NF-PSCs. A clear criterion in selection of donor polymers has been established for the SDIPBI-based NF-PSCs. Suitable energy level differences, finer morphology, and broad absorption ranges could be successively screened for donor polymers. Interestingly, NF-PSCs based on PBDTTPD/SDIPBI delivers a high V oc of 1.04 V and a desirable PCE of 3.4%. Moreover, the SDIPBI-based NF-PSC employing PBDTTT-EFT as donor polymer exhibits a high PCE up to 4.5%. The results implicate that to select donor polymers is a feasible strategy to boost the photovoltaic performance of NF-PSCs further. [ABSTRACT FROM AUTHOR]

Polymethacrylate with semiconducting side chains ( P1), synthesized by free radical polymerization, was used as a donor material for polymer solar cells. P1 is of high molecular weight ( Mn = 82 kg mol−1), good thermal stability, narrow band gap (1.87 eV), and low-lying HOMO energy level (−5.24 eV). P1 possesses not only the good film-forming ability of polymers but also the high purity of small organic molecules. Power conversion efficiencies (PCEs) of 0.63% and 1.22% have been obtained for solar cells with M1:PC71BM and P1:PC71BM as the active layers, respectively. With PC61BM as the acceptor, PCEs of M1 and P1 based devices decrease to 0.61% and 0.76%, respectively. To the best of our knowledge, this is the first report that free radical polymerization can be used to prepare polymer donors for photovoltaic applications. [ABSTRACT FROM AUTHOR]

Many advances in organic photovoltaic efficiency are not yet fully understood and new insight into structure-property relationships is required to push this technology into broad commercial use. The aim of this article is not to comprehensively review recent work, but to provide commentary on recent successes and forecast where researchers should look to enhance the efficiency of photovoltaics. By lowering the LUMO level, utilizing electron-withdrawing substituents advantageously, and employing appropriate side chains on donor polymers, researchers can elucidate further aspects of polymer-PCBM interactions while ultimately developing materials that will push past 10% efficiency. [ABSTRACT FROM AUTHOR]

An easy and efficient approach for the synthesis of an important photoelectric intermediate 3-fluoro-2-iodithiophene is developed. Therefrom, a polymer J52FF , featuring fluorination of the π-bridges on the backbone and side chains of the classical polymer, J52, is synthesized. J52FF displays a coplanar molecular configuration with the dihedral angles smaller than 2° in skeleton, a low-lying HOMO energy level of −5.62 eV, which is nearly aligned with the acceptor IT-4F, and a broad absorption range from 300 nm to 650 nm. The J52FF :IT-4F (1:0.8) blend shows a strong and complementary spectral absorption, a uniform fibrillar textured morphology and high and balanced charge mobilities. The inverted device based on J52FF :IT-4F blend obtained an encouraging power conversion efficiency (PCE) of 14.83% with the open-circuit voltage (V oc) of 0.90 V, the short circuit current (J sc) of 23.21 mA cm−2, and the fill factor (FF) of 0.71 under the optimal conditions, which is one of the best PCE value among the ever reported BDT-alt-BTz derivatives or IT-4F based non-fullerene organic solar cells (NF–OSCs). It demonstrates that fluorination of polymer in skeleton is an efficient strategy for obtaining high performance. • An easy and efficient approach for synthesis of 3-fluoro-2-iodithiophene was developed. • A novel polymer J52FF, featuring fluorination of the π-bridges on the backbone of J52 was synthesized. • The inverted device based on J52FF:IT-4F blend produced a PCE of 14.83% with a V oc of 0.90 V and a J sc of 23.21 mA cm−2. [ABSTRACT FROM AUTHOR]

In this report three new donor copolymers based on alternate octyl 3-fluorothieno[3,4- b ]thiophene-2-carboxylate as acceptor and benzo[1,2- b :4,5- b ′]dithiophene (BDT) derivatives having triisopropylethynylsilane (TIPS), triisopropyl((thiophen-2-yl)ethynyl)silane (TIPS-Th) and triisopropyl((3-octylthiophen-2-yl)ethynyl)silane (TIPS-ThC8) side chains as donors, (respectively named as P1 , P2 and P3) are synthesized to assess whether insertion of thiophene or alkyl thiophene units between TIPS side chains and BDT backbones can improve their properties and photovoltaic performance. Indeed, the modification of TIPS side chains on BDT backbone found to distinctly affect their opto-electrochemical properties, molecular orientations and nanoscale morphologies in resultant polymers. Among the polymers, optimized organic solar cells (OSCs) of P1 :PC 71 BM exhibited best power conversion efficiency (PCE) of 6.55% with a very high V OC of 1.02 V, thereby outperforming P2 and P3 (PCE of 4.72% and 5.47%, respectively). The detailed characterization of optimized blends revealed that this superior device performance of P1 :PC 71 BM blend films attributed to their compact and "face-on" molecular orientation, high hole mobility and superior nanoscale morphology, which minimized voltage loss and leading to an efficient charge transfer with low recombination losses in OCSs. In contrast, lower performances of P2 and P3 were mainly originating from their decreased solubilities caused by the insertion of TIPS-Th or TIPS-ThC8, thereby negatively affecting their molecular weights, morphology and charge carrier mobilities. Thus, these results provide a valuable guideline for designing polymers based on 2-TIPSTh substituted BDT units. Image 1 • Three new benzodithiophene based D-A type copolymers having different triisopropylsilylethynyl alkyl side chains were synthesized. • The effects of these different alkyl chains on the polymer properties and photovoltaic performance were systematically investigated. • The OSC based on P1 having linear TIPS side chains displayed a maximum PCE of 6.55%. [ABSTRACT FROM AUTHOR]

Design of terpolymers via copolymerization has emerged as a potential strategy for expanding the family of high-performing donor polymers and boosting the photovoltaic performance of non-fullerene polymer solar cells (PSCs). Herein, double-ester-substituted thiophenes and thienothiophenes are incorporated as third building blocks into the donor polymer PBDB-TF, developing two groups of terpolymers with donor-acceptor 1-donor-acceptor 2 (D-A1-D-A2)-type backbones. An optimum 10% concentration of double-ester-substituted thiophene units in PBDB-TF-T10 downshifts the molecular energy and increases the dielectric constant, and delivers proper miscibility and nanostructure in blends with the high-performing acceptor Y6. These characteristics are designed to synergistically enhance the photovoltage, photocurrent, and efficiency of PSCs. The resulting power conversion efficiency (PCE) of 16.4% surpasses the conventional PBDB-TF/Y6 PSCs, and it is among the best-performing PSCs based on PBDB-TF-derived terpolymers. Gratifyingly, PBDB-TF-T10 does not show significant batch-to-batch variation and it retains high PCEs above 16% in a broad range of molecular weights. This work introduces a facile strategy to easily synthesize terpolymers in combination with Y6 for the attainment of high-performing and reproducible non-fullerene PSCs.

Developing high-performance donor polymers is important for nonfullerene organic solar cells (NF-OSCs), as state-of-the-art nonfullerene acceptors can only perform well if they are coupled with a matching donor with suitable energy levels. However, there are very limited choices of donor polymers for NF-OSCs, and the most commonly used ones are polymers named PM6 and PM7, which suffer from several problems. First, the performance of these polymers (particularly PM7) relies on precise control of their molecular weights. Also, their optimal morphology is extremely sensitive to any structural modification. In this work, a family of donor polymers is developed based on a random polymerization strategy. These polymers can achieve well-controlled morphology and high-performance with a variety of chemical structures and molecular weights. The polymer donors are D-A1-D-A2-type random copolymers in which the D and A1 units are monomers originating from PM6 or PM7, while the A2 unit comprises an electron-deficient core flanked by two thiophene rings with branched alkyl chains. Consequently, multiple cases of highly efficient NF-OSCs are achieved with efficiencies between 16.0% and 17.1%. As the electron-deficient cores can be changed to many other structural units, the strategy can easily expand the choices of high-performance donor polymers for NF-OSCs., (© 2020 Wiley-VCH GmbH.)

It is of great significance to develop efficient donor polymers during the rapid development of acceptor materials for nonfullerene bulk-heterojunction (BHJ) polymer solar cells. Herein, a new donor polymer, named PBTT-F, based on a strongly electron-deficient core (5,7-dibromo-2,3-bis(2-ethylhexyl)benzo[1,2-b:4,5-c']dithiophene-4,8-dione, TTDO), is developed through the design of cyclohexane-1,4-dione embedded into a thieno[3,4-b]thiophene (TT) unit. When blended with the acceptor Y6, the PBTT-F-based photovoltaic device exhibits an outstanding power conversion efficiency (PCE) of 16.1% with a very high fill factor (FF) of 77.1%. This polymer also shows high efficiency for a thick-film device, with a PCE of ≈14.2% being realized for an active layer thickness of 190 nm. In addition, the PBTT-F-based polymer solar cells also show good stability after storage for ≈700 h in a glove box, with a high PCE of ≈14.8%, which obviously shows that this kind of polymer is very promising for future commercial applications. This work provides a unique strategy for the molecular synthesis of donor polymers, and these results demonstrate that PBTT-F is a very promising donor polymer for use in polymer solar cells, providing an alternative choice for a variety of fullerene-free acceptor materials for the research community., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Significant progress has been made in nonfullerene small molecule acceptors (NF‐SMAs) that leads to a consistent increase of power conversion efficiency (PCE) of nonfullerene organic solar cells (NF‐OSCs). To achieve better compatibility with high‐performance NF‐SMAs, the direction of molecular design for donor polymers is toward wide bandgap (WBG), tailored properties, and preferentially ecofriendly processability for device fabrication. Here, a weak acceptor unit, methyl 2,5‐dibromo‐4‐fluorothiophene‐3‐carboxylate (FE‐T), is synthesized and copolymerized with benzo[1,2‐b:4,5‐b′]dithiophene (BDT) to afford a series of nonhalogenated solvent processable WBG polymers P1‐P3 with a distinct side chain on FE‐T. The incorporation of FE‐T leads to polymers with a deep highest occupied molecular orbital (HOMO) level of −5.60−5.70 eV, a complementary absorption to NF‐SMAs, and a planar molecular conformation. When combined with the narrow bandgap acceptor ITIC‐Th, the solar cell based on P1 with the shortest methyl chain on FE‐T achieves a PCE of 11.39% with a large Voc of 1.01 V and a Jsc of 17.89 mA cm−2. Moreover, a PCE of 12.11% is attained for ternary cells based on WBG P1, narrow bandgap PTB7‐Th, and acceptor IEICO‐4F. These results demonstrate that the new FE‐T is a highly promising acceptor unit to construct WBG polymers for efficient NF‐OSCs. [ABSTRACT FROM AUTHOR]

Non‐fullerene polymer solar cells (NF‐PSCs) have achieved tremendous progress in power conversion efficiency (PCE), which is mainly attributed to the well absorption complementation and the admirable energy‐level alignment between donor polymers and fullerene‐free acceptors. However, the development of efficient donor polymers pairing with fullerene‐free acceptors relatively lags behind that of fullerene‐free acceptors in terms of number and diversity for fabricating NF‐PSCs. In this work, a two‐dimensional medium bandgap copolymer (PBDFFPD) based on benzo[1,2‐b:3,4‐b′]difuran (BDF) and furo[3,4‐c]pyrrole‐4,6‐dione (FPD), is firstly designed and synthesized. The as‐prepared polymer possesses a large conjugated plane with negligible torsion, strong intermolecular and intramolecular interaction, and deep highest occupied molecular orbital (HOMO) energy level. The optimized photovoltaic device based on PBDFFPD:ITIC wins a remarkable PCE of 9.58% with a large FF of 70.1%, the highest values ever reported for FPD‐based polymers. In addition, the statistical data from different batches of devices shows that PSCs based on PBDFFPD:ITIC at optimized conditions depict an excellent reproducibility of PCE with a deviation of 2.29%. The results demonstrate that PBDFFPD possesses great potential for constructing highly efficient NF‐PSCs. [ABSTRACT FROM AUTHOR]

Among the diverse nonfullerene acceptors, perylene bisimides (PBIs) have been attracting much attention due to their excellent electron mobility and tunable molecular and electronic properties by simply engineering the bay and head linkages. Herein, guided by two efficient small molecular acceptors, we designed, synthesized, and characterized a new nonfullerene small molecule PPDI with fine-tailored alkyl chains. Notably, a certificated PCE of 5.40% is realized in a simple structured fullerene-free polymer solar cell comprising PPDI as the electron acceptor and a fine-tailored 2D-conjugated polymer PBDT-TS1 as the electron donor. Moreover, the device behavior, morphological feature, and origin of high efficiency in PBDT-TS1/PPDI-based fullerene-free PSC were investigated. The synchronous selection and design of donor and acceptor materials reported here offer a feasible strategy for realizing highly efficient fullerene-free organic photovoltaics.