Trap-assisted large gain in Cu_2O/C_(60) hybrid ultraviolet/visible photodetectors

摘要

Photomultiplication-type ultraviolet (UV)/visible photodetectors (PDs) are demonstrated in an electrodeposited Cu_2O/C_(60) hybrid structure. These simple organic/inorganic hybrid PDs exhibit external quantum efficiencies (EQEs) of 1.1 × 10~4% under illumination of 365 nm UV light at -3 V, indicating a large gain of photocurrent for these devices. Such an EQE is one of the highest values among the reported organic/inorganic hybrid PDs at the same voltage. Cu_2O and C_(60) are found to play different roles in realizing the photomultiplication. Copper vacancies are proposed as the defects in the electrodeposited Cu_2O layers, which can trap photogenerated holes. Such trapped holes will trigger the injection of multiple electrons and hence result in the photocurrent gain of the devices while C_(60) primarily acts as a light absorption media to provide free holes.