Dual‐Percolative Planar‐Heterojunction Photoactive System for High‐Performance Stretchable Organic Photovoltaics Enhancing Power Output under Strain

Abstract Intrinsically stretchable organic solar cells (IS‐OSCs) are promising candidates for wearable power sources due to their ability to deform in multiple directions. However, their power conversion efficiency (PCE) and stretchability remain insufficient for practical applications. Here, a new dual percolative planar‐heterojunction ( DP‐PHJ ) photoactive architecture is presented, where the bottom and top layers comprise polymer donors (D18) and small‐molecule acceptors (L8‐BO), respectively, each at its percolation threshold relative to the other component. This architecture enables OSCs with a high PCE (> 19%) and exceptional mechanical robustness (toughness = 4.4 MJ m −3 ). The interconnected D18 and L8‐BO networks in both layers promote extensive donor–acceptor interfaces and efficient charge transport pathways. Simultaneously, robust D18 networks in the bottom layer dissipate mechanical stress, while percolated D18 in the top layer alleviates the brittleness of L8‐BO. Consequently, DP‐PHJ ‐based OSCs exhibit superior PCE (19%) and mechanical robustness (4.4 MJ m −3 ) compared to bulk‐heterojunction ( BHJ , PCE = 18% and toughness = 1.6 MJ m −3 ) and conventional PHJ (PCE = 17% and toughness = 3.1 MJ m −3 ) systems. Notably, IS‐OSCs based on DP‐PHJ architectures demonstrate strain‐induced power output enhancement across 0–30% strain, underscoring their potential for practical wearable applications.