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

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 mu A/cm(2). 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/cm(2) irradiance, and 0.6 V bias potential, the devices achieved a photocurrent density of 0.64 mu A/cm(2), 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/cm(2) and the bias voltage was raised from 0 V to 0.6 V, the photoresponsivity increased by 5.8 times, from 1 mu A/W to 5.8 mu A/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.