High-efficiency photon capturing in ultrathin silicon solar cells with front nanobowl texture and truncated-nanopyramid reflector.

We present a crystalline siliconthin-film (5 μm) solar cell decorated by a front nanobowled texture and a rear truncated-nanopyramid silver reflector. This design substantially suppresses the overall light reflection and enhances the optical resonances inside the silicon film leading to the photon-capturing performance comparable to the Yablonovitch limit. We show that optical absorption can be greatly improved by adjusting the ratio of the periods between the rear and front nanostructures with an optimal ultimate photocurrent density around 35.3  mA/cm² and an enhancement of 42.6% relative to the planar counterpart. A thorough optoelectronic simulation predicts the light-conversion efficiency of around 15.5%, i.e., 67.3% higher than that of the planar system.