Doping-Free High-Performance Photovoltaic Effect in a WSe Lateral Homojunction Formed by Contact Engineering.

Two-dimensional transition metal dichalcogenides (TMDs) are promising materials for semiconductor nanodevices owing to their flexibility, transparency, and appropriate band gaps. A variety of optoelectronic and electronic devices based on TMDs diodes have been extensively investigated due to their unique advantages. However, improving their performance is challenging for commercial applications. In this study, we propose a facile and doping-free approach based on the contact engineering of a few-layer tungsten di-selenide to form a lateral homojunction photovoltaic. By combining surface and edge contacts for diode fabrication, the photovoltaic effect is achieved with a high fill factor of ≈0.64, a power conversion efficiency of up to ≈4.5%, and the highest external quantum efficiency with a value of ≈67.6%. The photoresponsivity reaches 283 mA/W, indicating excellent photodiode performance. These results demonstrate that our technique has great potential for application in next-generation optoelectronic devices.