Achieving High Responsivity of Photoelectrochemical Solar-Blind Ultraviolet Photodetectors Via Oxygen Vacancy Engineering

Tin oxide (SnO 2 ) is an n-type wide-bandgap semiconductor with the merits of superior electron transport properties and good stability, making it an attractive candidate for solar-blind ultraviolet photodetectors (SBUV PDs). However, it is still challenging to design high-performance SnO 2 -based photoelectrochemical (PEC)-type SBUV PDs. In this study, oxygen vacancies (OVs) engineering is proposed to manipulate the photoresponse of SnO 2 nanosheets (NSs) and high-performance SnO 2 -based PEC SBUV PDs are developed. SnO 2 NSs with different OVs are prepared by hydrothermal method with annealing process. PEC PDs consisting of SnO 2 NSs annealed at 550 °C show record high responsivity and specific detectivity of 269.40 mA/W and 2.38×10 12 Jones at a bias voltage of 0.2 V, respectively, surpassing all aqueous-type PEC UV PDs. OVs simultaneously accelerate the carrier recombination in the SnO 2 NSs and charge transfer at the interface of the SnO 2 NSs and electrolyte, indicating that both excess OVs and too few OVs reduce the PEC photoresponse. Therefore, an appropriate OVs content is vital to designing high-performance SnO 2 NSs PEC PDs. Moreover, the SnO 2 NSs PEC PDs have good self-powered capability, excellent wavelength-selectivity, multicycle, and long-term stability. Our results demonstrate that OVs engineering is a powerful strategy for designing high-performance SnO 2 -based PEC PDs.