Superiority of random inverted nanopyramid as efficient light trapping structure in ultrathin flexible c-Si solar cell

In this work, random inverted nanopyramids (INPs) are fabricated as light trapping structures on ultrathin c-Si through a simple and cost-effective wet chemical method, followed by a systematic investigation of the photo-capturing properties of INPs combining experiments and simulations. In comprehensive consideration of thickness loss and light trapping performance, random INPs are applied onto 45 μm ultrathin c-Si solar cell and a high short-current density (Jsc) (36.6 mA/cm2) and energy-conversion efficiency (17.0%) are achieved, which are 0.3 mA/cm2 and 0.13% respectively higher than that in micro pyramid textured one, and our electrical simulation also demonstrates that the advantages of INPs are more obvious on thinner c-Si compared with conventional micro pyramids. Finally, through electrical simulation, INPs textured 45 μm c-Si solar cell is expected to have a large improvement room for efficiency by controlling the front and rear surface recombination velocity. All the findings not only offer additional insight into the light-trapping mechanism in the random INPs but also provide controllable and efficient broadband light harvesters for next-generation cost effective flexible photovoltaics.