Enhanced electrical conductivity of transparent electrode using metal microfiber networks for gridless thin-film solar cells

Improving the optical transmittance and electrical conductivity in transparent conductors (TC) has been a critical issue for decades due to their numerous applications. In this paper, we suggest an approach to produce extremely conductive TC material from electroplated Ni microfiber networks (NiMFs) in order to achieve highly efficient and aesthetically superior thin-film solar cells and modules. The high cross-sectional aspect ratio of NiMFs significantly enhanced their electrical conductivity and optical transmittance simultaneously. The TC structure employing NiMFs was a successful substitute for conventional patterned grids in Cu(In,Ga)Se-2 thin-film solar cells because it reduced the series resistance, which is especially advantageous for large-area cells. The NiMF-induced transmittance loss was compensated for by the formation of a light diffusion layer on the NiMF. We propose that the excellent performance of NiMF TC materials enables the elimination or significant reduction of the grids in thin-film solar cells and modules.