Reflectivity reduction of nanopatterned c-Si solar cells with antireflective coatings exposed to a wide range of incidence angles

Abstract

The scope of the present study is to assess through numerical calculations the effect of nanopatterning the photovoltaics (PV) and that of imposing additional superstrate layers to the efficiency of the PV’s, under normal and wide incidence angles. The numerical calculations were performed with the Rigorous Coupled-Wave Analysis (RCWA) method where we examined several types of Si wafers including additional Si3N4 and SiO2 superstrate layers, and periodic patterns of grooves affecting either the superstrates or both the superstrates and Si substrate. A very broad parameter space was investigated (thickness of the superstrates, and the depth, diameter and periodicity constant of hole and pillar-like patterns) from which we derived the optimal set of parameters for each wafer type. The performance of the optimized wafers was then evaluated over a broad range of incident angles. Both the deposition of the superstrates as well as the imposition of periodic patterns improve drastically the absorption efficiency of the wafers and they allow for maintaining the maximum efficiency across the high incidence angle regime.