Photoelectrochemical Photodetectors Based on WSe2/rGO Hybrid Structure with Enhanced Performance

Abstract

Efficient photoelectrochemical photodetectors based on WSe₂/rGO have been fabricated using an annealing process. The initial performance enhancement of these devices was primarily attributed to the improved bandgap structure of WSe₂ and the high carrier mobility of rGO, which facilitated an efficient transition of valence band electrons to the conduction band. Upon this understanding, a comparison between bulk WSe₂ and WSe₂ nanosheets (WSe₂ NSs) was conducted. It was found that, at a bias voltage of 0.6 V, the photocurrent density of WSe₂ NSs devices was 76% higher than that of similar bulk WSe₂ devices, reaching 0.044 μA/cm². Owing to the significant advantages of rGO, extensive testing of various WSe₂ to rGO ratios was performed, identifying the precise composition that optimized photoelectric performance. Notably, under conditions of 0.5 M Na₂SO₄ electrolyte, 120 mW/cm² irradiance, and 0.6 V bias potential, the devices achieved a photocurrent density of 0.64 μA/cm², which is approximately 25.72 times higher than that of bulk WSe₂ and 14.61 times more than WSe₂ NSs. Moreover, the photoresponse trended upward with increasing irradiation intensity. Specifically, when the irradiation intensity was increased to 160 mW/cm² and the bias voltage was raised from 0 V to 0.6 V, the photoresponsivity increased by 5.8 times, from 1 μA/W to 5.8 μA/W. The photodetectors constructed using the optimal WSe₂/rGO ratio exhibited no significant performance degradation during a 4000-s cyclic on/off test, demonstrating their robustness under operational conditions. This study highlights the substantial potential of WSe₂/rGO hybrids in enhancing the performance of photoelectrochemical photodetectors.