Self-Powered MXene/GaN van der Waals Heterojunction Ultraviolet Photodiodes with Superhigh Efficiency and Stable Current Outputs

A self-powered, high-performance Ti3C2Tx MXene/GaN van der Waals heterojunction (vdWH)-based ultraviolet (UV) photodiode is reported. Such integration creates a Schottky junction depth that is larger than the UV absorption depth to sufficiently separate the photoinduced electron/hole pairs, boosting the peak internal quantum efficiency over the unity and the external quantum efficiency over 99% under weak UV light without bias. The proposed Ti3C2Tx/GaN vdWH UV photodiode demonstrates pronounced photoelectric performances working in self-powered mode, including a large responsivity (284 mA W-1), a high specific detectivity (7.06 x 10(13) Jones), and fast response speed (rise/decay time of 7.55 mu s/1.67 ms). Furthermore, the remarkable photovoltaic behavior leads to an impressive power conversion efficiency of 7.33% under 355 nm UV light illumination. Additionally, this work presents an easy-processing spray-deposition route for the fabrication of large-area UV photodiode arrays that exhibit highly uniform cell-to-cell performance. The MXene/GaN photodiode arrays with high-efficiency and self-powered ability show high potential for many applications, such as energy-saving communication, imaging, and sensing networks.

Automated summary

A self-powered, high-performance Ti3C2Tx MXene/GaN van der Waals heterojunction-based ultraviolet photodiode with outstanding quantum efficiency and rapid response speed is reported, showing remarkable photovoltaic behavior and power conversion efficiency.