Solution-processed polymer photodetectors with trap-assisted photomultiplication

Abstract

Here, we report a trap-assisted photomultiplication (PM) phenomenon in solution-processed organic photodetectors (OPDs) using poly(3-hexylthiophene) (P3HT): indene-C60 bisadduct (ICBA) as the active layer. The maximum external quantum efficiency (EQE) is 685% for the device with 2% ICBA doping ratio, which is much higher than that of OPDs with P3HT:ICBA (1:1) as the active layer. The PM phenomenon is attributed to the hole tunneling injection assisted by trapped electron in ICBA near Al cathode, which can be demonstrated from the EQE spectra and transient photocurrent curves of OPDs with different ICBA doping ratios.