Trap-assisted large gain in Cu2O/C60 hybrid ultraviolet/visible photodetectors

Photomultiplication-type ultraviolet (UV)/visible photodetectors (PDs) are demonstrated in an electrodeposited Cu2O/C60 hybrid structure. These simple organic/inorganic hybrid PDs exhibit external quantum efficiencies (EQEs) of 1.1 × 104% 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. Cu2O and C60 are found to play different roles in realizing the photomultiplication. Copper vacancies are proposed as the defects in the electrodeposited Cu2O 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 C60 primarily acts as a light absorption media to provide free holes.