Self-powered 2D/3D heterojunction-based photodetectors with asymmetric MXene-layered electrodes

Self-powered photodetectors have attracted much attention due to their high detectivity and ultra-low power consumption for next-generation optoelectronic applications. Herein, we proposed what we believe to be a novel strategy to construct asymmetric Schottky contact between two-dimensional (2D) MXene and bulk Si by controlling the thickness of MXene films. Due to the different Schottky height-induced built-in fields, a net photocurrent was obtained under illumination with zero bias voltage (<i>V_bias</i>). The maximum photo responsivity obtained was 8.6 mA/W, and a high detectivity of 1.2 × 10¹¹ Jones was also demonstrated due to the ultra-low dark current at zero <i>V_bias</i>. Besides, the <i>V_bias</i>-dependent optoelectrical performance was comprehensively studied, demonstrating its great potential in high-performance photodetectors. This work provides a new strategy for integrating 2D electrodes with 3D photoactive layers to design self-powered optoelectronic devices.