Band offsets engineering at CdxZn1-xS/Cu2ZnSnS4 heterointerface简

CdxZn1-xS/Cu2ZnSnS4 （CZTS）-based thin film solar cells usually use Cd S as a buffer layer, but due to its smaller band gap（2.4 e V）, Cd S film has been replaced with higher band gap materials. The cadmium zinc sulfide（Cd Zn S） ternary compound has a higher band gap than other compounds, which leads to a decrease in window absorption loss. In this paper, the band offsets at CdxZn1-xS/Cu2ZnSnS4 （CZTS） heterointerface are calculated by the first-principles, densityfunctional and pseudopotential method. The band offsets at Cd1-xZnx S/CZTS heterointerface are tuned by controlling the composition of Zn in Cd1-xZnx S alloy, the calculated valence band offsets are small, which is consistent with the commonanion rule. The favorable heterointerface of type-I with a moderate barrier height（< 0.3 e V） can be obtained by controlling the composition of Zn in Cd1-xZnx S alloy between 0.25 and 0.375.