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

Self-driven photodetectors (SDPDs) convert photon energy into electrical signals without an external bias, making them ideal for low-power optoelectronic systems. Two-dimensional materials (2DMs) offer promising platforms due to their unique properties. However, current SDPD designs face challenges: 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, while multiphysical field coupling approaches rely heavily on specific material properties, limiting generalizability, and the resultant self-driven performance remains at a low level. This work reveals how different asymmetries can be combined to boost self-driven properties based on typical 2D metal-semiconductor-metal PDs without complex fabrication methods. Using WSe₂ as the model channel material, the synergistic effect of asymmetrical contact electrodes and contact geometries is systematically demonstrated. The open-circuit voltage (V_oc) of the synergistic SDPD reaches 0.58 V, increasing by 65% and 241%, respectively, compared to the two single asymmetrical effects. Additionally, our device exhibits great sensitivity for attenuated underwater visible light signals, enabled by its high zero-bias responsivity (5.77 A/W). The proposed method offers a universal strategy to build 2DMs-SDPDs for ultralow-power consumption optoelectronics based on multiple asymmetrical effects.