All-Solution-Processed Reduced Graphene Oxide Flexible Photodetectors for Use in Low-Light Environments

All-solution-processed reduced graphene oxide (rGO)-based flexible photodetectors (PDs) with asymmetric electrode structures of Ag nanowires (NWs) — Cu NWs are demonstrated for stable photodetection in weak-light environments. At first, we aimed to optimize the fabrication parameters of rGO layers for minimum roughness and high uniformity according to the field emission scanning electron microscope (FESEM) images; the average absorbance of optimal rGO layers is $\sim $ 17.4% from 400 to 1600 nm. Additionally, compared to Ag NWs — Ag NWs and Cu NWs — Cu NWs electrodes, rGO PDs with Ag NWs—Cu NWs asymmetric electrodes showed a higher photocurrent-to-dark-current ratio (PDCR) ( $\sim $ 6), which was due to the improved carrier transport with using Ag and Cu as cathodes and anodes. Furthermore, the highest photoresponsivity (5.5 mA/W) and detectivity ( $D^{\ast} $ ) ( $\sim {1}\times {10}^{{9}}$ cm Hz $^{{{1}/{2}}}$ /W) of rGO PDs with Ag NWs — Cu NWs electrodes have been measured and evaluated at 8 V bias. This work demonstrates the significant potential of all-solution processed rGO-based flexible PDs for high-performance and low-cost photosensing applications.

I. Introduction

With the development of novel materials and fabrication technologies, flexible photodetectors (PDs) are increasingly crucial for applications in health care, electronic skin, or consumer electronics (such as mobile phones and televisions) due to their mechanical deformations and elasticity [1].