Improving the device performance of CuO-based self-powered photodetectors by cobalt doping

CuO is a promising semiconductor for visible region optoelectronic applications with its suitable bandgap. In this study, 1 % and 2 % cobalt-doped CuO films were prepared by a chemical solution method. XRD results reveal that the films crystallize in a monoclinic crystal structure. The surfaces of the samples changed from having granular structures to spherical structures, according to SEM observations. Optical measurements show that the absorption coefficients of the samples are on the order of 10(5) cm(-1). According to the Tauc relation, the sample band gaps vary between 1.79 and 1.83 eV. The visible light photosensitivity of photodetectors prepared with FTO/TiO2/n-In2S3/p-CuO/P3HT/Ag hetero-structure increased by 520 %, from 68 to 424 with 1 % cobalt doping. In cobalt-doped photodetectors, a high-speed response was achieved with a very low rise and decay time of similar to 20 m s under zero bias conditions. Furthermore, time-current measurements repeated 100 times show that the photodetectors exhibit excellent stability and repeatability. The results obtained indicate that cobalt doping significantly increases both the diode characteristic of the heterojunction structure and the device performance.