Simulation an effective light trapping structure for boosting photoelectrocatalytic water splitting

Solar energy converted by photoelectrochemical (PEC) cells showcases significant potential for addressing the energy crisis. However, limitations stemming from photoelectrode structure have hindered the efficiency improvements of PEC cells. In this work, we utilized the finite-time domain difference method to simulate the PEC performance of GaAs photoanode in a PEC cell. Through finite element analysis, we determined the thickness of GaAs photoanode to be 265 nm and subsequently designed the concave-structured photoanode. Comparison of cross-sectional photoelectric characteristic between flat and concave structured photoanodes revealed significant improvements in the latter. Specifically, the absorption of concave structure increased by 30.61 % compared to flat structure, accompanied by 2.7 times increase in P_max and 2.2 times increase in J_SC. Further analysis of the impact of depth-to-width ratio and inner surface area on light-trapping characteristics demonstrated their influence on absorption and photoelectrical performance. Interestingly, concave structures presented a 14.70 % higher absorption compared to flat structures, translating to 1.48 times increase in surface area absorption rate. Moreover, the P_max increase was 3.08 times greater than the increase in surface area. We anticipate that our structural simulation findings will offer valuable theoretical insights for the design of light-trapping structures, thereby enhancing the performance of PEC cells.