The role of Z_nO:Al films in the performance of amorphous-silicon based tandem solar cells

Abstract

Degradation of textured S_nO₂:F films in glow-discharge hydrogen plasmas has been minimized by deposition ZnO:Al films onto them. This coating also prevents the diffusion of Sn atoms from S_nO₂:F into the stacked silicon layers of solar cells, while the transmittance and sheet resistivity remain unaltered. Another important aspect is the rear reflection at the back contact. Use of a Z_nO₂:Al layer as a back reflector at the n⁺/metal interface in a-Si:H tandem solar cells has been found to absorb light of the long-wavelength (λ>600nm) region in the solar spectrum. This improves the short-circuit current density and thereby the efficiency of amorphous silicon solar cells to a great extent.