Facile preparation of micron- and nano-scale textured master for nano-imprinting front electrode in thin-film silicon tandem cells with improved light trapping
This paper reports a facile method to prepare a textured surface with combined micron- and nano-scale surface features, which is used as master for nano-imprinting process to obtain transparent front electrodes in thin-film silicon tandem cells. The micron- and nano-scale surface features of the master are formed by combination of SiO2 sphere pre-deposition and ZnO textured growth. The master exhibits an averaged total transmittance value of 89.7% and an averaged haze value of 54.1% for the wavelength from 380 to 1100 urn. Comparing to the flat reference cell, the thin-film Si tandem cell deposited on the superstrate prepared using this master shows substantial decrease in reflectance at long wavelengths and drastic gain in the photocurrent of the bottom cell, the maximum summed current is enhanced by 35.5%, and the convert efficiency is improved from 8% to 10.0 +/- 0.3%. (C) 2015 Elsevier Ltd. All rights reserved.