Anodic aluminum oxide nanograting for back light trapping in thin c-Si solar cells

Enhanced absorption of near infrared light in silicon solar cells is important for achieving high conversion efficiencies while reducing the solar cell׳s thickness. In our work, a light trapping structure combined with anodic aluminum oxide (AAO) nanograting and Ag thin layer was proposed. The finite difference time domain (FDTD) method was used to study the relationship between AAO׳s geometrical parameters and light absorption character of thin Si solar cells. Simulation results show that the optimum AAO parameter is 0.75 for the duty circle, 380 nm for period and 90 nm for thickness. Absorption spectrum shows that, AAO in optimum structure can highly increase light absorption for Si solar cell in wavelength from 500 to 1100 nm. Parameter tolerance analyzing of AAO shows that, choosing AAO as a back light trapping structure allows a tolerance more than ±10% for period and about −5% to 20% for thickness.