Influence of the copper deficiency and anionic composition on band-energy diagram of bulk kesterite CZTSSe

The influence of the chemical composition on band edges and Fermi level Cu2ZnSn(SxSe1-x)4 stoichiometric compounds was investigated. Cu-poor compounds, Cu1.70Zn1.15SnSSe3 Cu1.70Zn1.15SnS2Se2, were also studied according to same approach. As already reported, absorption threshold increases linearly from 1.05 1.48 eV with increasing sulfur content. Simultaneously, conduction moves −4.4 −3.8 respectively, while position uppermost valence bands levels are almost not influenced by S/Se ratio. In contrast, for a significant change in surface is witnessed compared that bulk. Moreover, capability enhanced without modification optical gap. Cu off-stoichiometry influences notably positioning into These features could be at origin singular performances poor CZTSSe-based solar cell.