Ultrathin In 2 O 3 Nanosheets toward High Responsivity and Rejection Ratio Visible-Blind UV Photodetection.

Photoelectrochemical-type visible-blind ultraviolet photodetectors (PEC VBUV PDs) have gained ever-growing attention due to their simple fabrication processes, uncomplicated packaging technology, and high sensitivity. However, it is still challenging to achieve high-performance PEC VBUV PDs based on a single material with good spectral selectivity. Here, it is demonstrated that individual ultrathin indium oxide (In 2 O 3 ) nanosheets (NSs) are suitable for designing high-performance PEC VBUV PDs with high responsivity and UV/visible rejection ratio for the first time. In 2 O 3 NSs PEC PDs show excellent UV photodetection capability with an ultrahigh photoresponsivity of 172.36 mA W -1 and a high specific detectivity of 4.43 × 10 11 Jones under 254 nm irradiation, which originates from the smaller charge transfer resistance (R ct ) at the In 2 O 3 NSs/electrolyte interface. The light absorption of In 2 O 3 NSs takes a blueshift due to the quantum confinement effect, granting good spectral selectivity for visible-blind detection. The UV/visible rejection ratio of In 2 O 3 NSs PEC PDs is 1567, which is 30 times higher than that of In 2 O 3 nanoparticles (NPs) and exceeds all recently reported PEC VBUV PDs. Moreover, In 2 O 3 NSs PEC PDs show good stability and good underwater imaging capability. The results verify that ultrathin In 2 O 3 NSs have potential in underwater optoelectronic devices.