Organic Thin Film Transistor Material Based Photomultiplication Type Organic Photodetectors via Balancing Hole Tunneling Injection and Transport

Abstract

Photomultiplication type organic photodetectors (PM-OPDs) are prepared with organic thin film transistor (OTFT) material PC12TV12T as donor and PC₇₁BM as acceptor, the optimal weight ratio of PC12TV12T to PC₇₁BM is about 100:7. The external quantum efficiency (EQE) of optimal PM-OPDs is 9200% at 370 nm under -8 V bias, resulting from the hole tunneling injection induced by trapped electrons in PC₇₁BM surrounded by PC12TV12T near Al electrode. P3HT is deliberately selected as the third component due to its high absorption coefficient and the lowest unoccupied molecular orbital. The optimal ternary PM-OPDs exhibit the EQE and specific detectivity (D*) of 12600% and 7.63 × 10¹¹ Jones at 370 nm under -8 V bias. Meanwhile, the signal-to-noise (SNR) of PM-OPDs can be increases over twenty times by employing P3HT as a third component, benefiting from the markedly decreased dark current density. This work indicates that PC12TV12T used in OTFT should be an excellent host material for achieving PM-OPDs, benefiting from its high mobility and appropriate energy level.