Thermally Driven Supramolecular Chirality Evolution in Low‐Bandgap Fused‐Ring Conjugated Molecules for High‐Performance NIR Circularly Polarized Light Detection

ABSTRACT Near‐infrared (NIR) circularly polarized light (CPL) photodetection is of great importance due to its broad application potential in bioimaging, wearable healthcare, optical communication, and advanced optoelectronic systems. In this study, a supramolecular chirality evolution strategy in chiral low‐bandgap fused‐ring conjugated molecules (LFCs) is presented for high‐performance NIR CPL photodetection using Schottky barrier vertical organic field‐effect transistors (SB‐VOFETs). Halogen substitution combined with thermal annealing drives inversion and amplification of supramolecular chirality in enantiopure LFC thin films. F‐substituted LFCs exhibit progressive domain growth and hierarchical ordering with increasing annealing temperature, whereas Cl‐substituted LFCs show limited structural evolution above 150°C. These distinct crystallization behaviors directly correlate with chiroptical responses, with F‐substituted LFCs achieving a maximum absorption dissymmetry factor (| g _abs |) of ∼0.1. When integrated into SB‐VOFETs, the optimized chiral films enable highly efficient NIR CPL photodetection, delivering a photocurrent dissymmetry factor (| g _ph |) of ∼0.1, a specific detectivity of 4.9 × 10 ^{1 1} Jones, an external quantum efficiency exceeding 900%, and a fast response time of ∼600 µs at 850 nm. These metrics represent the highest performance reported for NIR CPL. This study provides design guidelines for advancing high‐performance chiral optoelectronic devices through the synergistic integration of atomic substitution, thermal annealing, and device architecture engineering.