Highly Sensitive Near‐Infrared Narrowband Photomultiplication Type Organic Photodetectors via Employing Charge Injection Narrowing and Exciton Dissociation Narrowing Strategy

Abstract A series of near‐infrared (NIR) narrowband photomultiplication type organic photodetectors (NB‐PM‐OPDs) are developed with the structure of ITO/PEDOT:PSS/P3HT:PTB7‐Th (1:1, w/w)/P3HT:PY‐DT (20:1, w/w)/Al. The P3HT:PTB7‐Th layer is deliberately selected as an organic filter layer (OFL) to suppress the photo‐response in the wavelength range below 750 nm. The P3HT:PY‐DT layer serves as photomultiplication layer to induce gain with external quantum efficiency (EQE) over 100%. The optimized OFL thickness is 1.3 µm to eliminate the photo‐response in the wavelength range below 750 nm and maintain high EQE values. The NB‐PM‐OPDs with 1.3 µm OFL exhibit NIR narrowband response with full width at half maximum of 76 nm and peak EQE of 1010% at 790 nm under −10 V bias. The signal‐to‐noise ratio (SNR) and specific detectivity ( D* ) of NB‐PM‐OPDs can be improved from 40 to 160 and from 5 × 10 11 to 2 × 10 12 Jones by replacing PEDOT:PSS with 2PACz as an interfacial layer. The narrowband response range of NB‐PM‐OPDs can be achieved by employing the strategies of exciton dissociation narrowing and charge injection narrowing, which may provide a feasible method in achieving NB‐PM‐OPDs working under low bias.