High-Photoelectric-Conversion ZnO NWs/PbS QDs Broadband Photodetector with an Innovative Interdigitated Electrode Structure

Abstract

Since the broadband photodetector can realize multiband detection and has strong application ability, it has a wide range of applications in the fields of information storage and broadband optical communication. The formation of heterostructures by selecting semiconductors with high electron mobility and narrow-band-gap quantum dots (QDs) is a controllable and excellent method to realize broadband detection of detectors from ultraviolet (UV) to near-infrared (NIR). This experimental study broadens the detection range of optoelectronic devices by introducing easily synthesized and band-gap-controlled PbS QDs to form a heterostructure with a ZnO film. By introducing ZnO nanowires (NWs) to form a three-dimensional (3D) bulk heterojunction structure, the interpenetration of ZnO NWs in the PbS QDs layer reduces the distance that minority carriers must diffuse before being injected into the depletion region, thereby improving the carrier collection efficiency. Further, the problem of limited thickness of the light-absorbing layer caused by insufficient electron collection length is effectively solved. The ZnO NWs/PbS QDs photoelectric device in this study guarantees the detection ability of the ultraviolet band while realizing wide band detection. The responsivity of the ultraviolet wave band is greatly improved, 52 times higher than that of the ordinary ZnO photoelectric device, the photocurrent can be increased by 40 times, and the external quantum efficiency (EQE) of the device can reach 255%. This research innovatively uses the interdigitated electrode structure to fabricate ZnO NWs/PbS QDs optoelectronic devices, which have better light utilization and stability. This research will have great reference significance for the development of controllable broadband photodetector applications.