High-mobility induced high-performance self-powered ultraviolet photodetector based on single ZnO microwire/PEDOT:PSS heterojunction via slight ga-doping

Semiconductor micro/nanostructures with broad bandgap can provide powerful candidates for fabricating ultraviolet photodetectors (PDs) due to their proper bandgap, unique optoelectronic properties, large surface-to-volume ratio and good integration. However, semiconducting micro/nanostructures suffer from low electron conductivity and abundant surface defects, which greatly limits their practical application in developing PDs. In this work, an ultraviolet PD consisting of single Ga-doped ZnO microwire (ZnO:Ga MW) and p-type poly(3,4ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was designed. When exposed to ultraviolet illumination, the PD exhibits excellent performance (responsivity ∼ 185 mA/W, detectivity ∼ 2.4 ×1011 Jones, and fast response speed of ∼ 212 μs for rise time and ∼ 387 μs for decay time) under self-driven conditions. Compared with that of an undoped ZnO MW-based PD, the responsivity and detectivity of ZnO:Ga MW/PEDOT:PSS PD are significantly enhanced over 400% and 600%, respectively. Due to the incorporation of Ga element, the charge transport properties of a ZnO:Ga MW, specifically for the mobility, are effectively enhanced, which can substantially facilitate the generation, separation, transport and harvest efficiency of photo-generated carriers in the as-fabricated PD. Besides, the Ga-incorporation improves the crystalline quality of MWs and reduces surface state density, further suggesting a high-quality ZnO:Ga MW/PEDOT:PSS heterojunction. This work provides a potential approach for designing high-performance self-powered ultraviolet PDs from the aspect of enhancing carrier transport through fine doping.