The Perylenediimide‐Based Cathode Interfacial Materials can “Kill” Nonfullerene Acceptors ITIC/Y6

High‐performance interfacial materials and nonfullerene electron acceptors (NFAs) play pivotal function in organic solar cells (OSCs). The representative cathode interfacial materials such as amine‐functionalized perylene‐diimide (PDINN), perylene diimide amino N‐oxide (PDINO), and poly fluorene electrolyte (PFN‐Br) are widely acceptable in the OSC community. Milestone NFAs materials like ITIC and Y6 or their similar derivatives have pushed forward the power conversion efficiency (PCE) gradually up to the photovoltaic efficiency top ceiling. However, the detrimental thermochemical reaction between perylenediimide‐based interfacial materials and NFAs is unknown which will be certainly correlated to device lifetime, even though it is well known that amine or alkali materials “attack” NFAs. Herein, the imide, which usually as interfacial materials functional groups, is accidentally observed to have caused fatal destruction to NFAs. A new carbanionic reaction mechanism is proposed based on experimental investigation. This study delves deep into present NFA OSCs devices’ decay problem, thereby facilitating the advancement of applicable OSCs.