Surface texturing studies of bilayer transparent conductive oxide (TCO) structures as front electrode for thin-film silicon solar cells

摘要

Surface textured transparent conductive oxide (TCO) thin films are widely used as the front electrode for thin-film silicon solar cells, as they can simultaneously provide good electrical conductance and optical management which improves the photon absorption via light scattering. In this paper, we report on bilayer TCO structures with enhanced electrical performance and good scattering properties. The bilayer TCO, made up of a highly conductive tin-doped indium oxide (ITO) layer and an etchable aluminium-doped (AZO) or intrinsic zinc oxide layer, are deposited onto soda-lime glass sheets via magnetron sputtering. The surface morphology of the ZnO films is subsequently modified using hydrochloric acid (HCl) etching. As for the bilayer TCO structure, the ITO mainly functions as the electrical layer and the surface textured ZnO acts as the optical layer for light scattering. Compared to single-layer AZO films, bilayer TCO films show different structural properties, which leads to disparate etching processes and thus different texturing properties.