Boosting the Self-driven Properties of 2D Photodetectors through Synergistic Asymmetrical Effects

TL;DR

This paper demonstrates how combining asymmetrical contact effects in 2D material-based photodetectors significantly enhances their self-driven performance, enabling efficient low-power optoelectronic applications.

Contribution

It introduces a novel strategy of synergistically combining asymmetrical contacts and geometries to boost self-driven properties of 2D photodetectors, validated through experiments and theory.

Findings

Achieved open-circuit voltage of 0.58V in WSe2 MSM photodetectors.

Demonstrated high responsivity of 5.77 A/W at zero bias.

Showed potential for underwater visible light communication.

Abstract

Self-driven photodetectors (SDPDs) transform photon energy into electrical energy without external voltage, which makes them highly advantageous for applications such as low-power communication and imaging systems. Two-dimensional materials (2DMs) provide ideal platforms for SDPDs thanks to their band structures covering ultraviolet to infrared spectrum, strong light absorption efficiencies, and high carrier mobilities. However, the lack of stable doping methods and the complicated 2DMs multilayer stacking techniques pose tremendous difficulties for 2DMs to adopt the same device structures (i.e. PN junctions) as bulk materials, and the resultant self-driven performance remains at a low level. This work reveals how different asymmetrical effects can be combined to synergistically boost self-driven properties based on typical 2D metal-semiconductor-metal (MSM) photodetectors. Using WSe2 as an exemplary 2D material to build MSM photodetectors, the synergistic effect of asymmetrical contact electrodes and asymmetrical contact geometries is theoretically and experimentally demonstrated. The open-circuit voltage (Voc) of the SDPD reaches 0.58V, with a zero-bias responsivity of 5.77 A/W and an on/off ratio of 1.73*10^5. Additionally, our devices demonstrate potential for visible light communication (VLC) in underwater environments. Our results offer a promising and efficient strategy for building SDPDs based on various 2DMs and pave the way toward low-power optoelectronic applications.