Green Modular Convergent Synthesis of Non-Fullerene Acceptor for SWIR Organic Photodetectors

Short-wavelength infrared organic photodetectors (SWIR OPDs) hold significant application potential due to their strong penetration depth and high resolution. However, the SWIR OPDs suffer from low SWIR sensitivity or large dark current under bias. In this study, an A-D-A'-D-A-type non-fullerene acceptor (NFA) with thiadiazoloquinoxaline as core unit, namely BTQ-Ph, was obtained through C-H activated direct arylation coupling and modular synthesis. The BTQ-Ph possessed an ultra-narrow optical bandgap of 0.95 eV with a maximum absorption peak at 1097 nm, indicating noticeable SWIR responsiveness. The SWIR OPD based on BTQ-Ph exhibited a broad spectral response from 500 to 1300 nm. The D_sh ^* value of BTQ-Ph-based OPD obtains 1.4 × 10¹³ Jones at 1110 nm and remains a high detectivity of 5.06 × 10¹² Jones at 1200 nm under self-powered mode. Importantly, a low dark current of 2.2 × 10^-7 A cm^-2 can be achieved under a working bias of -1.0 V, leading to a significant detectivity level exceeding 10¹¹ Jones. This work demonstrates that deeply engaging in the optimization of A-D-A'-D-A-type molecular framework is a highly effective approach for high-performing SWIR OPDs.