Hybrid silver nanoparticle and transparent conductive oxide structure for silicon solar cell applications

Abstract

Transparent conductive oxides (TCOs) have been widely used as electrodes for various solar cell structures. For heterojunction silicon wafer solar cells, the front TCO layer not only serves as a top electrode (by enhancing the lateral conductance of the underlying amorphous silicon film), but also as an antireflection coating. These requirements make it difficult to simultaneously achieve excellent conductance and transparency, and thus, only high-quality indium tin oxide (ITO) has as yet found its way into industrial heterojunction silicon wafer solar cells. In this Letter, we present a cost-effective hybrid structure consisting of a TCO layer and a silver nano-particle mesh. This structure enables the separate optimization of the electrical and optical requirements. The silver nanoparticle mesh provides high electrical conductance, while the TCO material is optimized as an antireflection coating. Therefore, this structure allows the use of cost-effective (and less conductive) TCO materials, such as aluminium-doped zinc oxide. The performance of the hybrid structure is demonstrated to achieve a similar visible transmission (~86% in the 380-780 nm range) as an 80 nm thick ITO layer, but with 10 times better lateral conductance. The presented hybrid structure thus seems well suited for a variety of photovoltaic devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.