Enhanced spectral response by silicon nitride index matching layer in amorphous silicon thin-film solar cells

Abstract

We employed the low temperature hydrogenated amorphous silicon nitride (a-SiNx:H) prepared by plasma-enhanced chemical vapor deposition as a refractive index (n) matching layers in a silicon-based thin-film solar cell between glass (n = 1.5) and the transparent conducting oxide (n = 2). By varying the stoichiometry, refractive index and thickness of the a-SiNx:H layers, we enhanced the spectral response and efficiency of the hydrogenated amorphous silicon thin-film solar cells. The refractive index of a-SiNx:H was reduced from 2.32 to 1.78. Optimizing the a-SiNx:H thickness to 80 nm increased the J(SC) from 8.3 to 9.8 mA/cm(2) and the corresponding cell efficiency increased from 4.5 to 53%, as compared to the cell without the a-SiNx:H index-matching layer on planar substrate. The a-SiNx:H layers with graded refractive indices were effective for enhancing the cell performance. (C) 2012 Elsevier B.V. All rights reserved.