Tailoring the photoresponse in surface-modified graphene oxide with environmentally-friendly synthesized ZnS and CuS nanoparticles

Notable progress has been achieved in the development of high-performance optoelectronics devices based on graphene oxide (GO) due to its distinctive electrical and optical attributes. This study furnishes an intriguing, eco-friendly approach for preparing nanocomposites comprising ZnS nanoparticles (NPs) embellished GO (ZnS-GO) and CuS NPs embellished GO (CuS-GO). Adhatoda vasica leaf extract acts as both a reducing agent and a linker, facilitating the attachment of ZnS and CuS NPs onto GO sheets. Thorough scrutiny was done on the materials deploying EDX, XPS, XRD, HRTEM, FESEM, PL, and FTIR techniques to endorse their elemental composition, phase purity, crystalline structure, surface morphology, and functional groups. Photodetectors prepared with Ag/ZnS-GO/Ag and Ag/CuS-GO/Ag configurations exhibited non-ohmic charge transport and photoconductive behavior in the visible spectrum. The tuning of these photodetectors was performed under illumination at wavelengths of 480 nm, 520 nm, and 670 nm across different bias voltages. Extensive on-off cycles were employed to evaluate the switching stability of the devices, demonstrating a clear photoresponse and photoswitching behavior. At a bias voltage of 30 V and an illumination wavelength of 480 nm, the ZnS-GO and CuS-GO photodetectors exhibited responsivities of 16.91 mA/W, 24.65 mA/W, and detectivities of 4.23 x 10⁹ Jones, 10.08 x 10⁹ Jones, respectively.