Photovoltaic solar cells based on organic−inorganic hybrid halide perovskites have achieved a substantial breakthrough via advanced interface engineering. Reports have emphasized that combining the hybrid perovskites with the Lewis base and/or graphene can definitely improve the performance through surface trap passivation and band alignment alteration; the underlying mechanisms are not yet fully understood. Here, using density functional theory calculations, we show that upon the formation of CH 3 NH 3 PbI 3 interfaces with three different Lewis base molecules and graphene, the binding strength with S-donors thiocarbamide and thioacetamide is higher than with O-donor dimethyl sulfoxide, while the interface dipole and work function reduction tend to increase from S-donors to O-donor. We provide evidences of deep trap state elimination in the S-donor perovskite interfaces through the analysis of defect formation on the CH 3 NH 3 PbI 3 (110) surface and of stability enhancement by estimation of activation barriers for vacancy-mediated iodine atom migrations. These theoretical predictions are in line with the experimental observation of performance enhancement in the perovskites prepared using thiocarbamide.
Perovskite solar cells have achieved a substantial breakthrough via advanced interface engineerings. Reports have emphasized that combining the hybrid perovskites with Lewis base and graphene improve the performance; the underlying mechanisms are not yet fully understood. Here, using density functional theory, we show that upon the formation of CH 3 NH 3 PbI 3 interfaces with three different Lewis base molecules and graphene, the binding strength with S -donors thiocarbamide and thioacetamide is higher than with O-donor dimethyl sulfoxide, while the interface dipole and work function reduction tend to increase from S -donors to O-donor. Furthermore, we provide evidences of deep trap states elimination in the S -donor perovskite interfaces through the analysis of defect formation on CH 3 NH 3 PbI 3 (110) surface, and of stability enhancement by estimating activation barriers for iodine atom migrations. These theoretical predictions are in line with the experimental observation of performance enhancement in the perovskites prepared using thiocarbamide.
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