A Non-fullerene Acceptor with Enhanced Intermolecular π‑Core Interaction for High-Performance Organic Solar Cells

Understanding the molecular structure and self-assembly of thia­diazole-derived non-fullerene acceptors (NFAs) is very critical for elucidating the origin of their extraordinary charge generation and transport properties that enable high power conversion efficiencies to be achieved in these systems. A comprehensive crystallographic study on a state-of-the-art NFA, Y6, and its selenium analog, CH1007, has been conducted which revealed that the face-to-face π-core interaction induced by benzo­[2,1,3]­thia­diazole S–N-containing moieties plays a significant role in governing the molecular geometries and unique packing of Y6 and CH1007 to ensure their superior charge-transport properties. Moreover, benefitting from the red-shifted optical absorption via selenium substitution, photo­voltaic devices based on a PM6:CH1007:PC71BM ternary blend delivered an exceptionally high short-circuit current of 27.48 mA/cm2 and a power conversion efficiency of 17.08%.解析噻二唑类非富勒烯受体（non-fullerene acceptors, NFAs）的分子结构与自组装行为，对于阐明这类材料优异电荷产生与传输特性的本源，进而实现其体系的高功率转换效率具有至关重要的意义。本研究针对一款当前顶尖的非富勒烯受体Y6及其硒取代类似物CH1007开展了全面的晶体学研究，结果显示：由苯并[2,1,3]噻二唑（benzo[2,1,3]thiadiazole）含S–N基团诱导产生的面对面π共轭核心相互作用，对调控Y6与CH1007的分子构型与独特堆积模式起到关键作用，从而赋予二者优异的电荷传输性能。此外，得益于硒取代带来的光学吸收红移效应，基于PM6:CH1007:PC71BM三元共混体系的光伏器件实现了27.48 mA/cm²的超高短路电流密度与17.08%的功率转换效率。