High-performance self-powered ultraviolet photodetector based on PEDOT:PSS/CuO/ZnO nanorod array sandwich structure

This study reports a sensitive self-powered ultraviolet photodetector (UV PD) fabricated with a facile cost-effective hydrothermal and RF magnetron sputtering combination method. The obtained PD is in sandwich configuration based on p-n junction, consisting of ZnO nanoarray bottom n-layer, poly (3, 4 ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) top p-layer, and CuO insertion layer. The developed PD shows superior self-powered performance with responsivity of 9.96 mA/W under weak UV illumination (365 nm, 0.4 mW/cm 2 ) and good wavelength selectivity ( R 365nm/ R 400nm = 4.87 × 10 2 ). It is found that the CuO insertion layer plays a vital role in the device performance, proving by the fact that the responsivity of the PD with the interlayer is almost 12 times that of the device without. This can be ascribed to the CuO thin layer which improves the junction quality by reducing the recombination centers for carriers, widening the depletion region and providing stepping energy levels between the band edges of ZnO and PEDOT:PSS, and thereby improves overall collection of the photo-generated carriers, leading to much improved photoresponse. The obtained PD also exhibits great multi-cycle stability. This efficient self-powered UV PD along with its cost-effective fabrication process is promising in UV sensor applications.