Spectral current-voltage analysis of kesterite solar cells

Abstract

Current–voltage analysis using different optical band pass filters has been performed on Cu2ZnSnSe4 and Cu2ZnSn(S,Se)4 thin-film solar cells. When using red or orange light (i.e. wavelengths above 600 nm), a distortion appears in the I–V curve of the Cu2ZnSnSe4 solar cell, indicating an additional potential barrier to the current flow in the device for these conditions of illumination. This barrier is reduced when using a Cu2ZnSn(S,Se)4 absorber. Numerical simulations demonstrate that the barrier visible under red light could be explained by a positive conduction band offset at the front interface coupled with compensating defects in the buffer layer.