Regulation of Oxygen Vacancies Enables Ultrastable Photoelectrochemical UV Photodetection

Abstract Wide‐bandgap semiconductive metal oxides used in photoelectrochemical (PEC) UV photodetectors suffer from poor cycling stability due to electron–hole recombination induced by hole accumulation on the surface and the sluggish reaction kinetics between the photogenerated holes and the surface adsorbents. Here it is reported that regulation of oxygen vacancies in SnO 2 nanoparticle clusters leads to dramatical enhancement of the cycling stability of PEC UV photodetection up to 24 h without photocurrent attenuation. Experimental analyses and theoretical calculation reveal that oxygen vacancies can not only induce shallow energy levels that act as “hole buffer center” to regulate the flow of holes to the electrode–electrolyte interface, but also accelerate surface oxidation reaction by lowering the energy barrier, which solves the issue of hole accumulation at the interface and results in greatly enhanced photocurrent stability. This work elucidates the roles of oxygen vacancies in manipulating the charge carrier behaviors in wide‐bandgap semiconductive metal oxides, which offers new perspectives for designing semiconductive metal oxides with enhanced optoelectronic performance.