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.