Advancing SWIR Organic Photodetectors through Molecular Design

Short-wave infrared (SWIR) organic photodetectors (OPDs) have emerged as promising candidates for low-cost, solution-processable photodetection; however, simultaneously extending the spectral response and maintaining efficient device operation remains a significant challenge. Herein, a series of core-engineered thiadiazoloquinoxaline (TQZ)-based non-fullerene acceptors was developed to systematically elucidate the influence of central-core structure on the optoelectronic properties and photodetection characteristics of SWIR OPDs. Progressive enhancement of the quinoidal character and π-electron delocalization effectively reduced the optical bandgap, resulting in extended SWIR absorption beyond 1300 nm. Although the most planar acceptor exhibited the broadest spectral response, the optimally twisted analogue delivered superior photodetector performance, achieving a responsivity of 144 mA W⁻¹ and a detectivity of 1.12 × 10¹² Jones. These findings reveal that spectral extension and device optimization are governed by distinct molecular characteristics, providing valuable design principles for high-performance SWIR organic photodetectors.