Double AAO nanogratings for broad spectrum absorption enhancement in thin film Si solar cells

• In this paper, we propose a light trapping structure combined of double AAO.
• Light trapping structure with AAO was once proposed by X. Sheng (on the rear, together with DBR ) and T.S.Yang (on the surface, together with TiO2), but the combined light trapping effect by introducing AAO to the surface and rear at the same time was barely reported.
• The influence of incident angle and the relative position of the surface and rear AAO's pore on light trapping was barely studied either. So our highlight in this paper is that, we proposed a double light trapping structure with AAO on the surface and rear of Si, and discussed some details, such as the influence of incident angle and the relative position of the surface and rear AAO's pore on light trapping.
• Beside, we use FDTD device to calculate some electrical properties of our design. Which is an interesting attemption since it can provide that our light trapping effect in more real condition.
• For its easy fabrication process and lost cost, the combined light trapping structure will have a high application potential.

In this paper, we presented a double light trapping structure containing anodic aluminum oxide (AAO) nanogratings on both the surface and rear of thin film crystalline silicon (c-Si) solar cell. Finite difference time domain (FDTD) method was used to study the light absorption enhancement of this design. Simulation results show that, the double light trapping structure can highly increase the light absorption in the wavelengths from 280 to 1100 nm. The relative enhancement of short-circuit current density (Jsc) in this situation is 137%. Besides, the double light trapping structure can highly reduce the influence of incident angle on light absorption. The relative position of AAO pore on the surface and rear has very little influence on light trapping.