Enhanced self-powered ion-modulated photodetector based on an asymmetric composite structure of superionic conductor RbAg4I5 and graphene

Abstract

Traditional strategies for self-powered devices face limitations in performance improvement due to the trade-off relationship between different parameters. Here, a new kind of ion-modulation self-powered photodetector is first proposed and fabricated by depositing superionic conductor RbAg4I5 on one side of monolayer graphene. The graphene homojunction is successfully formed at the boundary of the asymmetric structure due to the formation of bound states of ions and electrons at the contact interface. This kind of homojunction avoids the trade off between response parameters of traditional self-powered devices because the dissociation of bound states under light irradiation dominates the generation of a photocurrent. The experimental results indicate that the prepared photodetector can achieve great photo response with responsivity of 20 mA/W and a response speed of 700 µs for ultraviolet and visible light when no bias is applied, which is better than most existing graphene-based self-powered devices in single or overall parameters. Further, a semi-quantitative model is systematically established according to the internal mechanism and realizes a good consistency with experimental results. The work provides a new idea and offers the foundation to develop excellent self-powered devices based on superionic materials with good properties in controllability and modulation.