The influence of the degree of Cu-Zn disorder on the radiative recombination transitions in Cu2ZnSn(S,Se)4 solar cells

Cu₂ZnSn(S,Se)₄ absorbers show disorder in the Cu-Zn lattice planes, which affects the band gap energy. The degree of disorder can be changed via post-annealing treatments. We report on the influence of this Cu-Zn disorder on the radiative recombination transitions in Cu₂ZnSn(S,Se)₄ solar cells. Temperature- and power-dependent photoluminescence measurements were performed to evaluate this influence. With increasing excitation power the samples show a large blue-shift of the photoluminescence peak energy while with increasing temperature at constant excitation power they show a red-shift. From an analysis of the shifting behavior as a function of the degree of Cu-Zn disorder we conclude that the degree of disorder does not alter the dominant recombination mechanism significantly.