Abstract: In this paper, the performance of the n-ZnO/i-AlSb/p-AlSb solar cell is simulated by AMPS(Analysis of microelectronic and photonic structures). The effect of n/i interface state on the performance of the solar cell, such as fill factor FF and conversion efficiency η, was studied. It was shown that with the increase in interface state density, fill factor and conversion efficiency decreased rapidly, the mechanism of this change was investigated as well.