the power conversion efficiencies (PCEs) of OSCs show rapid increase and the values have increased to over 18%. [16][17][18][19][20][21][22][23][24] However, owing to the brittle nature of small molecules, [25] the mechanical properties of polymer:NF-SMA blends are generally insufficient and can hardly meet the requirement of stretchable electronics. [26,27] The mechanical imperceptibility of OSCs requires low stiffness and high extensibility for wearable and portable applications. The human skin exhibits a ductility of about 30%, which is the benchmark for skin-wearable devices. [28] Studies have been carried out to determine the mechanical properties of nonfullerene OSCs [29][30][31] and drive the development of stretchable OSCs. [32][33][34][35] For instance, the fracture strain of the well-known PTB7-Th:(3,9-bis(2-methylene-(3-(1,1dicyanomethylene)-indanone))-5,5,11,11tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene) (ITIC) blend films decreased dramatically with the increase of ITIC, and the blend films became significantly stiffer as a result of increased elastic modulus. [26,36] Therefore, methods should be adopted to improve the stretchability and reduce the stiffness of OSCs based on polymer:NF-SMA blends.As the mechanical performance of polymer:NF-SMA blends are often poor, a representative high-efficiency Top-performance organic solar cells (OSCs) consisting of conjugated polymer donors and nonfullerene small molecule acceptors (NF-SMAs) deliver rapid increases in efficiencies. Nevertheless, many of the polymer donors exhibit high stiffness and small molecule acceptors are very brittle, which limit their applications in wearable devices. Here, a simple and effective strategy is reported to improve the stretchability and reduce the stiffness of highefficiency polymer:NF-SMA blends and simultaneously maintain the high efficiency by incorporating a low-cost commercial thermoplastic elastomer, polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS). The microstructure, mechanical properties, and photovoltaic performance of PM6:N3 with varied SEBS contents and the molecular weight dependence of SEBS on microstructure and mechanical properties are thoroughly characterized. This strategy for mechanical performance improvement exhibits excellent applicability in some other OSC blend systems, e.g., PBQx-TF:eC9-2Cl and PBDB-T:ITIC. More crucially, the elastic modulus of such complex ternary blends can be nicely predicted by a mechanical model. Therefore, incorporating thermoplastic elastomers is a widely applicable and cost-effective strategy to improve mechanical properties of nonfullerene OSCs and beyond.

Power-conversion efficiencies (PCEs) higher than 19% have been realized from single-junction organic photovoltaics. [4][5][6][7][8] Moreover, ongoing studies on morphology control, energy loss, photophysical analysis, and photon utilization improve our understanding of the photoelectric conversion processes and motivate the development of OSCs. [9][10][11][12][13][14][15][16][17][18] Fundamental intermolecular interactions are widely known, important, and ubiquitous; however, their complicated impact on organic photovoltaics have not been comprehensively researched.Intermolecular interactions, including those between like and unlike molecules, are prevalent in OSCs. Apart from interactions between different layers, [19] intermolecular interactions play complicated roles in heterojunction active layers, owing to multiple-component mixed systems involving thermodynamics and kinetics procedures. [20] Brédas et al. illustrated the detailed relationship between donor/acceptor (D/A) interactions and polarizability, the charge-transfer state, and charge-separated state in fullerene solar cells, thereby highlighting the significance of interactions from the perspective of theoretical simulations. [21] Hou et al. controlled D/A interactions using halogenated end-caps of acceptors and Research on organic solar cells (OSCs) has progressed through material innovation and device engineering. However, well-known and ubiquitous intermolecular interactions, and particularly their synergistic effects, have received little attention. Herein, the complicated relationship between photovoltaic conversion and multidimensional intermolecular interactions in the active layers is investigated. These interactions are dually regulated by side-chain isomerization and end-cap engineering of the acceptors. The phenylalkyl featured acceptors (LA-series) exhibit stronger crystallinity with preferential face-on interactions relative to the alkylphenyl attached isomers (ITIC-series). In addition, the PM6 and LA-series acceptors exhibit moderate donor/acceptor interactions compared to those of the strongly interacting PM6/ITIC-series pairs, which helps to enhance phase separation and charge transport. Consequently, the output efficiencies of all LA series acceptors are over 14%. Moreover, LA-series acceptors show appropriate compatibility, host/guest interactions, and crystallinity relationships with BTP-eC9, thereby leading to uniform and well-organized "alloy-like" mixed phases. In particular, the highly crystalline LA23 further optimizes multiple interactions and ternary microstructures, which results in a high efficiency of 19.12%. Thus, these results highlight the importance of multidimensional intermolecular interactions in the photovoltaic performance of OSCs.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202208986.

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.