Three-dimensional porous In2O3 arrays for self-powered transparent solar-blind photodetectors with high responsivity and excellent spectral selectivity

Transparent solar-blind ultraviolet photodetectors (SBUV PDs) have extensive applications in versatile scenarios, such as optical communication. However, it is still challenging to simultaneously achieve high responsivity, high transparency, and satisfying self-powered capability. Here, we demonstrated high-performance, transparent, and self-powered photoelectrochemical-type (PEC) SBUV PDs based on vertically grown ultrathin In2O3 nanosheet arrays (NAs) with a three-dimensional (3D) porous structure. The 3D porous structure simultaneously improves the transmittance in the visible light region, accelerates interfacial reaction kinetics, and promotes photogenerated carrier transport. The performance of In2O3 NAs photoanodes exceeds most reported self-powered PEC SBUV PDs, exhibiting a high transmittance of approximately 80% in the visible light region, a high responsivity of 86.15 mA/W for 254 nm light irradiation, a fast response speed of 15/18 ms, and good multicycle stability. The In2O3 NAs also show excellent spectral selectivity with an ultrahigh solar-blind rejection ratio of 1319.30, attributed to the quantum confinement effect induced by the ultrathin feature (2–3 nm). Furthermore, In2O3 NAs photoanodes show good capability in underwater optical communication. Our work demonstrated that a 3D porous structure is a powerful strategy to synchronously achieve high responsivity and transparency and provides a new perspective for designing high-performance, transparent, and self-powered PEC SBUV PDs.