Bismuth oxysulfide films with giant external quantum efficiency: Investigation of photoelectrochemical properties and stability in dimethyl sulfoxide solutions for application in photodetectors

Within the scope of the work, we investigate the photoelectrochemical properties of chemically deposited bismuth oxysulfide films (BOS) in a dimethyl sulfoxide (DMSO) solution of quinhydrone. The films demonstrate an appearance of a cathodic photocurrent under negative electrochemical polarization and high external quantum efficiency (EQE) values up to 340%. The electrochemical potential window of BOS films, they can operate, is very broad and comprises from -1.0 to 1.7 V vs. standard hydrogen electrode (SHE). The detailed investigation of BOS films with XRD, SEM, EDX and XPS shows the absence of any changes in the phase composition, morphology, bulk, and surface elemental composition of the BOS film after photoelectrochemical impact for half of the year. The photoelectrochemical results were used to design of UV-Vis-NIR photodetector, which has a responsivity up to 1.2 A/W at 465 nm. This value significantly exceeds the previously reported responsivity values for bismuth oxysulfide based photodetectors.