Broadband Organic Photodetectors Exhibiting Photoresponse up to 1400 nm enabled by a Fused Thiophene-based Non-Fullerene Acceptor with Difluoro-Substituted End Groups
Broadband organic photodetectors (OPDs) are promising for multispectral imaging and environmental monitoring. However, extending the photoresponse into the short-wave infrared (SWIR) region while maintaining high sensitivity remains challenging. Here, we report novel non-fullerene acceptors (NFAs) based on a fused thiophene core, 6QC and 6QCF, exhibiting absorption edges of 1230 nm and 1295 nm, respectively. In particular, 6QCF incorporates difluoro-substituted end groups, which enhance intramolecular charge transfer and reduce the bandgap. Furthermore, by leveraging Fabry–Perot resonance via active-layer thickness optimization, the PTB7-Th:6QCF device achieved photoresponse up to 1400 nm beyond that of the PTB7-Th:6QC device, while delivering a maximum responsivity of 85.9 mA W−1 and a specific detectivity of 4.04 × 1010 Jones. These results demonstrate that difluoro-substituted end group engineering extends absorption into the SWIR region and enables high-performance broadband OPDs.