Synthesis of silver sulfide nanoparticles and their photodetector applications.

Silver sulfide nanoparticles (Ag 2 S 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 Ag 2 S NPs by using a sonochemistry method and the fabrication of photodetector devices through the integration of Ag 2 S NPs atop a graphene sheet. We have also synthesized Li-doped Ag 2 S 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 Ag 2 S NPs. Finally, high-performance photodetectors based on CVD graphene and Ag 2 S NPs were demonstrated and investigated; the hybrid photodetectors based on Ag 2 S NPs and Li-doped Ag 2 S 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.