Highly improved photocurrent of a flexible MoS2 photodetector via a backside Al metal mirror and its in- and outward folding states

Abstract

High-performance foldable and flexible photodetectors have been extensively studied for next-generation hinged electronics and AR/VR technology. The need to maintain efficiency in the folded state restricts the development of strategies aimed at further improving the efficiency of photodetectors. For the first time, we introduce a simple and effective method for the photocurrent improvement of a molybdenum disulfide (MoS₂) flexible photodetector by attaching a backside Al metal mirror and folding it in- and outward. Under light illumination, the Al film underneath the MoS₂ photodetector acts as a flat reflective metal mirror and further functions as a concave mirror under the inward folded state. In this state, the proposed device with the backside Al metal mirror improved photocurrent from 4.04 μA to 8.53 μA under illumination (a λ_ex of 405 nm with a P_inc of 0.3 mW cm⁻²) compared to the device on a flat polyimide (PI) substrate without the Al metal mirror. Our work provides new insights into high-performance flexible photodetectors in the inward and outward folded states, which will be beneficial for future foldable/hinged electronics and AR/VR devices.