Enhancement in photocurrent by dual-interface period-mismatched rotating rectangle grating-based c-Si solar cells.

A dual-interface period-mismatched rotating rectangular grating structure was designed for crystalline silicon thin film solar cells. The relevant parameters of the grating structures were optimized, and the absorption enhancement mechanisms were also explained by optoelectronic simulation analysis. The numerical results show that the rotating rectangular structure can improve the light-trapping performance by coupling light into the c-Si film to excite the waveguide mode and localized surface plasmon resonances. Moreover, it is found that the light-trapping effect of the rear grating rotating structure is better than that of the front grating rotating structure, because the rear interface can better excite localized surface plasmon resonances. The photocurrent density of the dual-interface period-mismatched rotating rectangular grating structure is increased to $18.01\; {\rm mA/cm}^2$, which is 76.05% higher than that of the planar 300 nm thick c-Si structure. The research results provide general guidance for the design of grating structures for thin-film solar cells.