Probing the effect of selenization on RF sputtered WSe₂ thin films toward enhanced photoelectrochemical and photodetection performance

Tungsten diselenide (WSe₂) is one of the promising two-dimensional materials among transition metal dichalcogenide (TMDCs) for its application in solar hydrogen production and optoelectronics devices. In this paper, we report the synthesis of WSe₂ thin films using RF-magnetron sputtering followed by post-selenizationin in purview of their use for photoelectrochemical (PEC) water splitting and photodetection applications. Characterization of selenized WSe₂ film shows improved structural, optical, and electrical properties compared to as-deposited WSe₂ film. The PEC evaluation shows that the selenized WSe₂ photocathode has improved photocurrent density, stability, and charge transfer properties compared to the as-deposited film. Furthermore, the selenized WSe₂ thin film photodetector demonstrated excellent performance, including better responsivity of 1.2 μA/W and detectivity of 9.5 × 10⁵ Jones with enhanced response time under one sun illumination. These results highlight a simple fabrication approach for producing scalable and high-quality WSe₂ thin films for next-generation optoelectronics devices. The post-selenization step can effectively heal defects and optimize optoelectronic properties.