Synthesis of silver sulfide nanoparticles and their photodetector applications

Silver sulfide nanoparticles (Ag₂S NPs) are currently being explored as infrared active nanomaterials that can provide environmentally stable alternatives to heavy metals such as lead. In this paper, we describe the novel synthesis of Ag₂S NPs by using a sonochemistry method and the fabrication of photodetector devices through the integration of Ag₂S NPs atop a graphene sheet. We have also synthesized Li-doped Ag₂S NPs that exhibited a significantly enhanced photodetector sensitivity via their enhanced absorption ability in the UV-NIR region. First-principles calculations based on a density functional theory formalism indicated that Li-doping produced a dramatic enhancement of NIR photoluminescence of the Ag₂S NPs. Finally, high-performance photodetectors based on CVD graphene and Ag₂S NPs were demonstrated and investigated; the hybrid photodetectors based on Ag₂S NPs and Li-doped Ag₂S NPs exhibited a photoresponse of 2723.2 and 4146.0 A W^-1 respectively under a light exposure of 0.89 mW cm^-2 at 550 nm. Our novel approach represents a promising and effective method for the synthesis of eco-friendly semiconducting NPs for photoelectric devices.