Improved opto-electronic properties of silicon heterojunction solar cells with SiOx/Tungsten-doped indium oxide double anti-reflective coatings

Amorphous SiOx was prepared by plasma enhanced chemical vapor deposition (PECVD) to form SiOx/tungsten-doped indium oxide (IWO) double anti-reflective coatings for silicon heterojunction (SHJ) solar cell. The sheet resistance of SiOx/IWO stacks decreases due to plasma treatment during deposition process, which means thinner IWO film would be deposited for better optical response. However, the comparisons of three antireflective coating (ARC) structures reveal that SiOx film limits carier transport and the path of IWO-SiOx-Ag structure is non-conductive. The decrease of sheet resistance is defined as pseudo conductivity. IWO film capping with SiOx allows observably reduced reflectance and better response in 300-400 and 600-1200nm wavelength ranges. Compared with IWO single ARC, the average reflection is reduced by 1.65% with 70nm SiOx/80nm IWO double anti-reflective coatings (DARCs) in 500-1200nm wavelength range, leading to growing external quantum efficiency response, short circuit current density (Jsc), and efficiency. After well optimization of SiOx/IWO stacks, an impressive efficiency of 23.08% is obtained with high Jsc and without compromising open circuit voltage (Voc) and fill factor. SiOx/IWO DARCs provide better anti-reflective properties over a broad range of wavelength, showing promising application for SHJ solar cells. (C) 2017 The Japan Society of Applied Physics