Defect control for high efficiency antimony selenosulfide solar cells by interface Engineering of buried monoatomic aluminum oxide layer

Antimony selenosulfide (Sb2(S,Se)3) reveals excellent optoelectronic characteristics, positioning it as a propitious light-absorbing substance with potential applications in photovoltaic technology. However, a multitude of deep-level defects significantly limit the efficiency of Sb2(S,Se)3 solar cells. In this study, the density of the surface and deep-level defects was reduced by adding a monoatomic Al2O3 layer on the surface of CdS film. Compared to the as-deposited film, highly [hk1]-oriented Sb2(S,Se)3 film having significantly enhanced charge separation was obtained. The addition of a monoatomic Al2O3 layer effectively modified the energy band structure by increasing the valence band maximum and more intrinsic Sb2(S,Se)3 film between n-type CdS layers and p-type spiro. This contributed to increased carrier collection and reduced carrier recombination. Ultimately, 9.39 % efficiency of the device were obtained as a result of the optimized orientation and reduced defects. Consequently, this research demonstrates an effective method for optimizing crystallographic orientation and minimizing defect density, thereby maximizing the efficiency of Sb2(S,Se)3 solar cells.