Terminal Fluorination Modulates Crystallinity and Aggregation of Fully Non‐Fused Ring Electron Acceptors for High‐Performance and Durable Near‐Infrared Organic Photodetectors

Abstract

High dark current density (Jd) severely hinders further advancement of near‐infrared organic photodetectors (NIR OPDs). Herein, we tackle this grand challenge by regulating molecular crystallinity and aggregation of fully non‐fused ring electron acceptors (FNREAs). In contrast to the general trend in terminal halogenation of electron acceptors, TBT‐V‐F, featuring fluorinated terminals, notably demonstrates crystalline intensification and a higher prevalence predominance of J‐aggregate compared to its chlorinated counterpart (TBT‐V‐Cl). The amalgamation of advantages confers TBT‐V‐F‐based OPDs with more organized active layer morphology and denser molecular packing, resulting in improved charge transport, decreased energetic disorder, and reduced trap density. Consequently, the corresponding self‐powered OPDs exhibit a 40‐fold decrease in Jd, a remarkable increase in detectivity (D*sh), faster response time, and superior thermal stability compared to TBT‐V‐Cl‐based OPDs. Further interfacial optimization results in an ultra‐low Jd of 7.30´10‐12 A cm‐2 with D*sh over 1013 Jones in 320‐920 nm wavelength and a climax of 2.2´1014 Jones at 800 nm for the TBT‐V‐F‐based OPDs, representing one of the best results reported to date. This work paves a compelling material‐based strategy to suppress Jd for highly sensitive NIR OPDs, while also illustrates the viability of FNREAs in construction of stable and affordable NIR OPDs for real‐world applications.