Recent Progress in Flexible and Stretchable Organic Solar Cells

Flexible and stretchable organic solar cells (OSCs) have attracted enormous attention due to their potential applications in wearable and portable devices. To achieve flexibility and stretchability, many efforts have been made with regard to mechanically robust electrodes, interface layers, and photoactive semiconductors. This has greatly improved the performance of the devices. State‐of‐the‐art flexible and stretchable OSCs have achieved a power conversion efficiency of 15.21% (16.55% for tandem flexible devices) and 13%, respectively. Here, the recent progress of flexible and stretchable OSCs in terms of their components and processing methods are summarized and discussed. The future challenges and perspectives for flexible and stretchable OSCs are also presented.     

Ternary Blend Strategy for Achieving High‐Efficiency Organic Solar Cells with Nonfullerene Acceptors Involved

Nonfullerene acceptors have recently drawn considerable attention in bulk heterojunction organic solar cells (OSCs). The power conversion efficiency (PCE) over 14% is achieved in single‐junction fullerene‐free OSCs, which has surpassed that of fullerene‐based counterparts. For future commercial applications, however, a high and stable PCE > 15% is required, which entails rational material design and device optimization. In this context, three approaches are generally utilized—the synthesis of novel nonfullerene acceptors and the selection of suitable polymer donors to pair with them, the tandem or multijunction device architecture, and the ternary blend strategy. Compared to the former two methods, the ternary strategy allows to employ the existing photovoltaic materials and the single‐junction device. Therefore, an exploration of nonfullerene acceptor–based ternary blend OSCs (NFTSCs) has shown unprecedented progress since 2016. This review summarizes and classifies the photovoltaic materials utilized in NFTSCs, aiming to not only exhibit the recent development of NFTSCs but also elucidate the correlation among donor/acceptor materials, film morphology, transport dynamics, and device fabrication toward high‐efficiency OSCs. Lastly, the above key advances are highlighted along with the existing issues and insights into the viable path for the further research thrusts are offered.     

Perovskite and Organic Solar Cells Fabricated by Inkjet Printing: Progress and Prospects

Inkjet printing (IJP) technology, adapted from home and office printing, has proven to be an essential research tool and industrial manufacturing technique in a wide range of printed electronic technologies, including optoelectronics. Its primary advantage over other deposition methods is the low‐cost and maskless on‐demand patterning, which offers unmatched freedom‐of‐design. Additional benefits include the efficient use of materials, contactless high‐resolution deposition, and scalability, enabling rapid translation of learning from small‐scale, laboratory‐based research into large‐scale industrial roll‐to‐roll manufacturing. In the development of organic solar cells (OSCs), IJP has enabled the printing of many of the multiple functional layers which comprise the complete cell as part of an additive printing scheme. Although IJP is only recently employed in perovskite solar cell (PeSC) fabrication, it is already showing great promise and is anticipated to find broader application with this class of materials. As OSCs and PeSCs share many common functional materials and device architectures, this review presents a progress report on the IJP of OSCs and PeSCs in order to facilitate knowledge transfer between the two technologies, with critical analyses of the challenges and opportunities also presented.     

Roll‐to‐roll gravure printing of organic photovoltaic modules—insulation of processing defects by an interfacial layer

Gravure printing as direct patterning roll‐to‐roll (R2R) production technology can revolutionize the design of thin‐film organic photovoltaic (OPV) devices by allowing feasible manufacturing of arbitrary‐shaped modules. This makes a distinction to coating methods, such as slot die coating, in which the pattern is limited to continuous stripes. Here, we analyze the thin‐film formation and its influence on OPV module performance as the gravure printing of hole transport and photoactive layers are transferred from laboratory to R2R pilot production environment. Insertion of a 0.8‐nm layer of lithium fluoride (LiF) as an interfacial layer between the active layer and the electron contact provided insulation against the detrimental pinholes formed in the R2R printing process. Using this device configuration, we produced well‐performing R2R‐printed monolithic modules with a mean efficiency of 1.7%. In comparison, reference modules with an efficiency of 2.2% were fabricated using laboratory‐scale bench top sheet‐level process. Surface energy and tension measurements together with optical microscopy were used to analyze the printability of the materials. The pinhole insulation was investigated in detail by processing R2R‐printed OPV modules with different interfacial layer materials and performing electrical measurements under dark and AM1.5 illumination conditions. Furthermore, we analyzed the LiF distribution using X‐ray photoelectron spectroscopy. The insulating nature of the LiF layer to improve module performance was confirmed by manufacturing lithographically artificial pinholes in device structures. The results show the possibility to loosen the production environment constraints and the feasibility of fabricating well‐performing thin‐film devices by R2R gravure printing. Copyright © 2014 John Wiley & Sons, Ltd.     

Fibril Network Strategy Enables High‐Performance Semitransparent Organic Solar Cells

The development of semitransparent organic solar cells (ST‐OSCs) represents a significant step toward the commercialization of OSCs. However, the trade‐off between power conversion efficiency (PCE) and average visible transmittance (AVT) restricts further improvements of ST‐OSCs. Herein, it is demonstrated that a fibril network strategy can enable ST‐OSCs with a high PCE and AVT simultaneously. A wide‐bandgap polymer PBT1‐C‐2Cl that can self‐assemble into a fibril nanostructure is used as the donor and a near‐infrared small molecule Y6 is adopted as the acceptor. It is found that a tiny amount of PBT1‐C‐2Cl in the blend can form a high speed pathway for hole transport due to the well distributed fibril nanostructure, which increases the transmittance in the visible region. Meanwhile, the acceptor Y6 guarantees sufficient light absorption. Using this strategy, the optimized ST‐OSCs yield a high PCE of 9.1% with an AVT of over 40% and significant light utilization efficiency of 3.65% at donor/acceptor ratio of 0.25:1. This work demonstrates a simple and effective approach to realizing high PCE and AVT of ST‐OSCs simultaneously.     

Gold(III) Corroles for High Performance Organic Solar Cells

While the use of molecular materials having long‐lived triplet excited state(s) for harvesting solar energy could be an effective approach to boost up the power conversion efficiency (PCE) of organic solar cells (OSCs), the performances of this kind of OSCs as reported in the literature are low (< 2.9% PCE attained for the vacuum‐deposited OSCs). Herein is described the realization of high performance OSCs by using gold(III) 5,10,15‐triphenylcorrole ( Au‐C1 ), gold(III) 10‐(p‐trifluoromethylphenyl)‐5,15‐diphenylcorrole ( Au‐C2 ), and gold(III) 10‐(pentafluorophenyl)‐5,15‐diphenyl‐corrole ( Au‐C3 ), as electron‐donors. These gold(III) corroles display excited state lifetimes of ≥ 25 μs and low emission quantum yields of < 0.15%. With the complexes Au‐C1 , Au‐C2 , and Au‐C3 , vacuum‐deposited OSCs, which give PCEs of 2.7%, 3.0%, and 1.8%, respectively, are fabricated. The PCE can be further boosted up to 4.0% after thermal treatment of the OSC devices. Meanwhile, a solution‐processed OSC based on Au‐C2 with a high PCE of 6.0% is fabricated. These PCE values are among the best reported for both types of vacuum‐deposited and solution‐processed OSCs fabricated with metal‐organic complexes having long‐lived excited states as electron‐donor material. The underlying mechanism for the inferior performance of the reported OSCs is discussed.     

Mechanistic Investigation into Dynamic Function of Third Component Incorporated in Ternary Near‐Infrared Nonfullerene Organic Solar Cells

Organic solar cells (OSCs) consisting of an ultralow‐bandgap nonfullerene acceptor (NFA) with an optical absorption edge that extends to the near‐infrared (NIR) region are of vital interest to semitransparent and tandem devices. However, huge energy‐loss related to inefficient charge dissociation hinders their further development. The critical issues of charge separation as exemplified in NIR‐NFA OSCs based on the paradigm blend of PTB7–Th donor (D) and IEICO–4F acceptor (A) are revealed here. These studies corroborate efficient charge transfer between D and A, accompanied by geminate recombination of photo‐excited charge carriers. Two key factors restricting charge separation are unveiled as the connection discontinuity of individual phases in the blend and long‐lived interfacial charge‐transfer states (CTS). By incorporation of a third‐component of benchmark ITIC or PC₇₁BM with various molar ratios, these two issues are well‐resolved accordingly, yet in distinctly influencing mechanisms. ITIC molecules modulate film morphology to create more continuous paths for charge transportation, whereas PC₇₁BM diminishes CTS and enhances electron transfer at the D/A interfaces. Consequently, the optimal untreated ternary OSCs comprising 0.3 wt% ITIC and 0.1 wt% PC₇₁BM in the blend deliver higher J_SC values of 21.9 and 25.4 mA cm^‐2, and hence increased PCE of 10.2% and 10.6%, respectively.     

Hot-Casting Boosts Efficiency of Halogen-Free Solvent Processed Non-Fullerene Organic Solar Cells

Despite the substantial climb of the power conversion efficiency (PCE) of organic solar cells (OSCs), the majority of processing solvent remains halogenated and stand as a critical issue for commercialization. Herein, a halogen-free solvent system consisting of toluene (Tol) and 1-phenylnaphthalene (PN) is used to replace the traditional halogenated chloroform (CF) and1-chloronaphthalene (CN) for the processing of the PM6:M36 OSC, reducing the maximum PCE from 15.0% to 13.3%. Hot-casting is demonstrated to boost the maximum PCE of halogen-free solvents processed OSCs back to 15.2%. The preheated substrate fastens the evaporation of Tol and enables similar film-forming kinetics to CF, resulting in the inhibition of immoderate molecular aggregation and excessive phase separation. Ternary OSCs, with either another donor or acceptor as the third component, can further improve device PCE to 15.8%, confirming the versatile photovoltaic systems that this hot-casting method can be applied to. Encouragingly, the hot-casting processed binary and ternary OSCs also exhibit retained storage stability. Therefore, hot-casting is demonstrated as a superior strategy to fabricate OSCs without efficiency and stability loss using halogen-free solvents.     

Boosting Performance of Non‐Fullerene Organic Solar Cells by 2D g‐C3N4 Doped PEDOT:PSS

The power‐conversion efficiency (PCE) of single‐junction organic solar cells (OSCs) has exceeded 16% thanks to the development of non‐fullerene acceptor materials and morphological optimization of active layer. In addition, interfacial engineering always plays a crucial role in further improving the performance of OSCs based on a well‐established active‐layer system. Doping of graphitic carbon nitride (g‐C₃N₄) into poly(3,4‐ethylene‐dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a hole transport layer (HTL) for PM6:Y6‐based OSCs is reported, boosting the PCE to almost 16.4%. After being added into the PEDOT:PSS, the g‐C₃N₄ as a Bronsted base can be protonated, weakening the shield effect of insulating PSS on conductive PEDOT, which enables exposures of more PEDOT chains on the surface of PEDOT:PSS core‐shell structure, and thus increasing the conductivity. Therefore, at the interface between g‐C₃N₄ doped HTL and PM6:Y6 layer, the charge transport is improved and the charge recombination is suppressed, leading to the increases of fill factor and short‐circuit current density of devices. This work demonstrates that doping g‐C₃N₄ into PEDOT:PSS is an efficient strategy to increase the conductivity of HTL, resulting in higher OSC performance.     

Releasing Acceptor from Donor Matrix to Accelerate Crystallization Kinetics with a Second Donor toward High-Efficiency Green-Printable Organic Photovoltaics

The state-of-the-art power conversion efficiency (PCE) of organic solar cells (OSCs) is typically achieved in the devices fabricated by toxic halogen solvents with complex post-treatment processes in strictly inert atmosphere. Developing suitable processing method for printing in ambient air using eco-friendly solvents with continuous solution supply and fabricating efficient devices without any post-treatment are intensively desired. Controlling the crystallization kinetics to fine-tune the acceptor's assembly behavior with a second donor for favorable morphological evolution is an effective approach to achieve above requirements. Herein, a kinetics-controlling strategy is implemented by introducing a strong crystalline small molecule, BTR-Cl, to enhance the crystallinity of acceptors. The combined in situ spectra characterizations revealed that the earlier aggregation of acceptor and modulation in conformation of PM6 can be achieved. This unique aggregation behavior facilitated enhanced film crystallization with reduced paracrystallinity of π–π stacking, resulting in improved charge transport and inhibited charge recombination. An outstanding PCE of 17.50% is obtained for the device processed with o-xylene via ambient air printing without any post-treatment. More significantly, efficient all-printed inverted devices and large-area modules are prepared. The generalization of this strategy has been confirmed in other efficient systems, suggesting a great potential for universally fabricating high-efficiency and eco-friendly OSCs.     

Intrinsically Stretchable Organic Solar Cells beyond 10% Power Conversion Efficiency Enabled by Transfer Printing Method

Stretchable organic solar cells (OSCs) simultaneously possessing high-efficiency and robust mechanical properties are ideal power generators for the emerging wearable and portable electronics. Herein, after incorporating a low amount of trimethylsiloxy terminated polydimethylsiloxane (PDMS) additive, the intrinsic stretchability of PTB7-Th:IEICO-4F bulk heterojunction (BHJ) film is greatly improved from 5% to 20% strain without sacrificing the photovoltaic performance. The intimate multi-layers stacking of OSCs is also realized with the transfer printing method assisted by electrical adhesive “glue” D-Sorbitol. The resultant devices with 84% electrode transmittance exhibit a remarkable power conversion efficiency (PCE) of 10.1%, which is among the highest efficiency for intrinsically stretchable OSCs to date. The stretchable OSCs also demonstrate the ultra-flexibility, stretchability, and mechanical robustness, which keep the PCE almost unchanged at small bending radium of 2 mm for 300 times bending cycles and retain 86.7% PCE under tensile strain as large as 20% for the devices with 70% electrode transmittance. The results provide a universal method to fabricate highly efficient intrinsically stretchable OSCs.     

Secondary Bonds Modifying Conjugate‐Blocked Linkages of Biomass‐Derived Lignin to Form Electron Transfer 3D Networks for Efficiency Exceeding 16% Nonfullerene Organic Solar Cells

Fabricating high‐efficient electron transporting interfacial layers (ETLs) with isotropic features is highly desired for all‐directional electron transfer/collection from an anisotropic active layer, achieving excellent power conversion efficiency (PCEs) on nonfullerene acceptor (NFA) organic solar cells (OSCs). The complicated synthesis and cost‐consumption in exploring versatile materials arouse great interest in the development of binary‐doping interlayers without phase separation and flexible manipulation. Herein, for the first time, a novel cathode interfacial layer based on biomass‐derived demethylated kraft lignin (D_MeKL) is proposed. Features of multiple phenolic‐hydroxyl (PhOH) and uniform‐distributed render D_MeKL to exhibit an excellent bonding capacity with amino terminal substituted perylene diiminde (PDIN), and successfully form a high‐efficient isotropic electron transfer 3D network. Synchronously, secondary bonds completely modify conjugate‐blocked linkages of D_MeKL, significantly enhance the electron transporting performance on cross‐section and vertical‐sections, and repair the contact of PDIN with active layer. The D_MeKL/PDIN‐based 3D‐network exhibits well‐matched work function (WF) (–4.34 eV) with cathode (–4.30 eV) and energy level of electron acceptor (–4.11 eV). D_MeKL/PDIN‐based NFAs‐OSC shows excellent short‐circuit current density (26.61 mA cm^–2) and PCE (16.02%) beyond the classic PDIN‐based NFA‐OSC (25.64 mA cm^–2, 15.41%), which is the highest PCEs among biomaterials interlayers. The results supply a novel method to achieve high‐efficient cathode interlayer for NFAs‐OSCs.     

A Universal Method to Enhance Flexibility and Stability of Organic Solar Cells by Constructing Insulating Matrices in Active Layers

With the rapid development of power conversion efficiency (PCE), flexibility–stability of organic solar cells (OSCs) are becoming one of the primary barriers for commercialization. This work shows that insulating poly(aryl ether) (PAE) resins have highly twisted‐stiff backbones without any side chains, which possess excellent mechanical stability, thermal stability, and good compatibility with organic photovoltaic materials. After introducing 5 wt% PAE resin as supporting matrices into the bulk heterojunction (BHJ) layer, the device yields a high PCE of 16.13%. Importantly, the devices show impressive flexibility and improved stability with passivated morphology, such as PM6/Y6‐based devices with 30 wt% PAE retains the PCE of 15.17% and exhibits enhanced 4.4‐fold elongation at break (25.07%). This is the recorded stretchability of the BHJ layer for OSCs with PCE > 8%, and morphological changes during tensile deformation are first investigated by in situ wide‐angle X‐ray scattering measurements. The PAE matrices strategy exhibits good universality in the other four photovoltaic systems. These results demonstrate that heat‐resistant PAE resins serve as supporting matrices with a tunneling effect into OSCs without sacrificing photovoltaic performance and simultaneously improve the flexibility and stability of devices, which can play an important role in promoting the development of stable and wearable electronics.     

Printable and Large‐Area Organic Solar Cells Enabled by a Ternary Pseudo‐Planar Heterojunction Strategy

Bulk heterojunction (BHJ) processing technology has had an irreplaceable role in the development of organic solar cells (OSCs) in the past decades due to the significant advantages in achieving high‐power conversion efficiency (PCE). However, the difficulty in exploring and regulating morphology makes it inadequate for upscaling large‐area OSCs. In this work, printable high‐performance ternary devices are fabricated by a pseudo‐planar heterojunction (PPHJ) strategy. The fullerene derivative indene‐C₆₀ bisadduct (ICBA) is incorporated into PM6/IT‐4F system to expand the vertical phase separation and facilitate an obvious PPHJ structure. After the addition of ICBA, the IT‐4F enriches on the surface of active layer, while PM6 is accumulated underneath. Furthermore, it increases the crystallinity of PM6, which facilitates exciton dissociation and charge transfer. Accordingly, 1.05 cm² devices are fabricated by blade‐coating with an enhanced PCE of 14.25% as compared to the BHJ devices (13.73%). The ternary PPHJ strategy provides an effective way to optimize the vertical phase separation of organic semiconductor during scalable printing methods.     

High-Performance Green Thick-Film Ternary Organic Solar Cells Enabled by Crystallinity Regulation

The power conversion efficiency (PCE) of organic solar cells (OSCs) has reached high values of over 19%. However, most of the high-efficiency OSCs are fabricated by spin-coating with toxic solvents and the optimal photoactive layer thickness is limited to 100 nm, limiting practical development of OSCs. It is a great challenge to obtain ideal morphology for high-efficiency thick-film OSCs when using non-halogenated solvents due to the unfavorable film formation kinetics. Herein, high-efficiency ternary thick-film (300 nm) OSCs with PCE of 15.4% based on PM6:BTR-Cl:CH1007 are fabricated by hot slot-die coating using non-halogenated solvent (o-xylene) in the air. Compared to PM6:BTR-Cl:Y6 blends, the stronger pre-aggregation of CH1007 in solution induces the earlier aggregation of CH1007 molecules and longer aggregation time, and thus results in high and balanced crystallinity of donors and acceptor in CH1007-based ternary film, which led to high-carrier mobility and suppressed charge recombination. The ternary strategy is further used to fabricate high-efficiency, thick-film, large-area, and flexible devices processed from non-halogenated solvents, paving the way for industrial development of OSCs.     

Solution-processed tandem organic solar cells

Organic solar cells(OSCs)show great potential in non-grid energy supply due to its unique properties including light-weight,flexibility,semi-transparency,design flexibility,low cost and so on.Thanks to researchers'tremendous efforts in materials development and device engineering,the power con-version efficiency(PCE)for single-junction OSCs(SJ-OSCs)has exceeded 18％[1,2].Further increasing PCE is still demanded in order to make this technology commercially attractive.Sev-eral directions have been proposed to push the PCE of SJ-OSCs beyond 20％[3],e.g.,reducing non-radiative voltage loss,increasing both exciton and charge-carrier mobility,redu-cing optical loss and so on.Most of the requirements rely on next breakthroughs in materials development.By maximiz-ing the utilization of solar energy,theoretically,tandem organ-ic solar cells(T-OSCs)can achieve a higher PCE than the state-of-the-art SJ-OSCs.Here,we highlight high-perform-ance T-OSCs with active layers made by solution-processing.     

High Power Conversion Efficiency of 13.61% for 1 cm2 Flexible Polymer Solar Cells Based on Patternable and Mass-Producible Gravure-Printed Silver Nanowire Electrodes

With the aim of developing high-performance flexible polymer solar cells, the preparation of flexible transparent electrodes (FTEs) via a high-throughput gravure printing process is reported. By varying the blend ratio of the mixture solvent and the concentration of the silver nanowire (AgNW) inks, the surface tension, volatilization rate, and viscosity of the AgNW ink can be tuned to meet the requirements of gravure printing process. Following this method, uniformly printed AgNW films are prepared. Highly conductive FTEs with a sheet resistance of 10.8 Ω sq⁻¹ and a high transparency of 95.4% (excluded substrate) are achieved, which are comparable to those of indium tin oxide electrode. In comparison with the spin-coating process, the gravure printing process exhibits advantages of the ease of large-area fabrication and improved uniformity, which are attributed to better ink droplet distribution over the substrate. 0.04 cm² polymer solar cells based on gravure-printed AgNW electrodes with PM6:Y6 as the photoactive layer show the highest power conversion efficiency (PCE) of 15.28% with an average PCE of 14.75 ± 0.35%. Owing to the good uniformity of the gravure-printed AgNW electrode, the highest PCE of 13.61% is achieved for 1 cm² polymer solar cells based on the gravure-printed FTEs.     

Elimination of Drying-Dependent Component Deviation Using a Composite Solvent Strategy Enables High-Performance Inkjet-Printed Organic Solar Cells with Efficiency Approaching 16%

Inkjet printing (IJP) is a roll-to-roll (R2R) compatible fabrication method for large-area organic solar cells (OSCs). Unlike the coating process, the films are formed through droplet leveling and merging during IJP, and the pre-deposited droplets are partly dissolved by the subsequent droplets. Such a process yields undesired printing pattern lines, especially in large-area printed films. This study reveals that such a temperature-dependent “drying lines-related” phase separation morphology has caused component variation in the organic blend films, which leads to an obvious inhomogeneity of photocurrent in the printed OSCs. Such a phenomenon is attributed to the solubility difference between organic donor and acceptor molecules in the main printing solvent. A composite solvent strategy of ortho-dichlorobenzene (oDCB)/trimethylbenzene (TMB) and tetralin (THN) is developed to solve this problem. The introduction of THN suppresses the formation of printing drying lines during high-temperature printing due to the preferential miscibility of acceptor in THN, leading to the efficiency improvement to 13.96% and 15.78% for the binary and ternary devices. In addition, the 1 cm² device with a disruptive pattern gives an efficiency of 12.80% and a certificated efficiency of 12.18%.     

Tuning the Intermolecular Electrostatic Interaction toward High-Efficiency and Low-Cost Organic Solar Cells

Organic solar cells (OSCs) have achieved much progress with rapidly increasing power conversion efficiencies (PCEs). It should be noted that the top-performance OSCs are generally consisted of active materials with complex chemical structures, resulting in high costs. Here, combining the material design and morphology control, high-efficiency OSCs are fabricated by a low-cost donor: acceptor blend. A completely non-fused electron acceptor named Tz is designed and synthesized via introducing thiazole units on both sides of a bithiophene core, which shows an outstanding PCE of 13.3% with a typical polythiophene donor. More importantly, optimization guidelines are presented to get excellent morphology for low-cost donor:acceptor systems. Three polythiophenes are selected, poly(3-hexylthiophene) and its two derivatives with electron-withdrawing substitutions (PDCBT and PDCBT-2F), as donors to fabricate the cell devices. The computational and experimental data reveal that decreasing the electrostatic interaction between polythiophene and Tz is the key to getting a suppressed miscibility and thus a high phase purity. This study provides insight into the molecular design and donor:acceptor matching requirements for high-efficiency and low-cost OSCs.     

Molecular Orientation Unified Nonfullerene Acceptor Enabling 14% Efficiency As‐Cast Organic Solar Cells

Molecular orientation and π–π stacking of nonfullerene acceptors (NFAs) determine its domain size and purity in bulk‐heterojunction blends with a polymer donor. Two novel NFAs featuring an indacenobis(dithieno[3,2‐b:2?,3?‐d]pyrrol) core with meta‐ or para‐alkoxyphenyl sidechains are designed and denoted as m‐INPOIC or p‐INPOIC , respectively. The impact of the alkoxyl group positioning on molecular orientation and photovoltaic performance of NFAs is revealed through a comparison study with the counterpart ( INPIC‐4F ) bearing para‐alkylphenyl sidechains. With inward constriction toward the conjugated backbone, m‐INPOIC presents predominant face‐on orientation to promote charge transport. The as‐cast organic solar cells (OSCs) by blending m‐INPOIC and PBDB‐T as active layers exhibit a power conversion efficiency (PCE) of 12.1%. By introducing PC₇₁BM as the solid processing‐aid, the ternary OSCs are further optimized to deliver an impressive PCE of 14.0%, which is among the highest PCEs for as‐cast single‐junction OSCs reported in literature to date. More attractively, PBDB‐T: m‐INPOIC :PC₇₁BM based OSCs exhibit over 11% PCEs even with an active layer thickness over 300 nm. And the devices can retain over 95% of PCE after storage for 20 days. The outstanding tolerance to film thickness and outstanding stability of the as‐cast devices make m‐INPOIC a promising candidate NFA for large‐scale solution‐processable OSCs.