N ‐Annulated Perylene‐Based Hole Transporters for Perovskite Solar Cells: The Significant Influence of Lateral Substituents

Perylene derivatives are a family of well‐known organic electron‐transporting materials with excellent photochemical and thermal stabilities, and have been widely used in various optoelectronic devices. In this work, two diphenylamine functionalized N ‐annulated perylenes are reported as hole‐transporting materials (HTMs) for perovskite solar cells. Through joint theoretical and experimental studies, the HTM employing a methoxyphenyl lateral substituent is found to feature a closer stacking distance and better aggregate connectivity in the solid film than its analogue with the bulky 2‐hexyldecyl lateral substituent, contributing to a higher hole mobility and a remarkably enhanced device performance of perovskite solar cells. This work demonstrates the significant influence of lateral substituents of HTMs on the intermolecular packing and solid microstructure, giving a clear insight on the molecular design of high‐performance organic semiconductors.