Broadband spectral response of diamond wire sawn mc-Si solar cell with omnidirectional performance and improved appearance

Abstract

Highly efficient diamond wire sawn (DWS) multi-crystalline Si (mc-Si) solar cells with a satisfactory visual appearance are expecting to dominate the photovoltaic industry soon. Here, we report the realization of broadband spectral response of DWS mc-Si solar cells with omnidirectional performance and improved appearance. The success lies in the effective surface texturization based on MACE technique followed by post acid modification and the introduction of SiO2/SiNx stack layers on the rear side. Bowl-like pits with an open size of about 1µm are uniformly formed on the Si surface regardless of the crystallographic directions, which significantly enhances the antireflection ability in the short wavelength and makes the grain boundaries less noticeable. We have also shown that the bowl-like textured cells possess exceptional optical absorption over wide angles of incidence from 0° to 70°. Moreover, the SiO2/SiNx stack layers enhance the rear internal reflection and passivation, effectively increasing the long wavelength absorption and suppressing the electrical losses. We have successfully mass-produced DWS mc-Si solar cells with an average efficiency of 19.1%, which is 1.2% absolutely higher than that of the conventional micro-textured counterparts.