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Insight into the reaction mechanism of water, oxygen and nitrogen molecule on the tin iodine perovskite surface


In this article, in order to study the Lead-free perovskite CH3NH3SnI3’s (MASnI3) reaction mechanism between perovskite surface molecules and gas molecules, we fabricated the models of three different gas molecules adsorbing on MASnI3 surface. Firstly, the surface energies of seven low-index surfaces((100), (010), (001), (110), (101), (011) and (111)) of orthorhombic MASnI3 were calculated by Density Functional Theory (DFT). The result showed the (011) surface was the most stable surface among the seven low index surfaces by the PW91 method. Secondly, three stable configurations was sorted out from these adsorption models of different molecules (H2O, O2, N2) at six positions on the (011) surface. For H2O, O2 and N2 adsorption, the smallest adsorption energies were -1.931(934) eV, -0.134(67) eV and -0.049(523) eV, respectively. Stability of configurations for H2O adsorption were affected by the strong interaction of H-I bond. However, for O2 adsorption, the Sn-O bond and the charge transfer between the Sn atom and O atom affected the stability of the configuration. We found that the MASnI3 surface in N2 atmosphere kept higher stability than in the other two cases. In addition, we further confirmed that the mechanism of H2O adsorption was not same with the O2 and N2 molecule adsorption by the Mulliken population, energy band and electrical density of state calculation. The results indicated that H-I bond and Sn-O bond mainly affect the Sn-I bond, leading to the MASnI3’s stability is not good in the H2O and O2 environments, respectively, and the performance in N2 environment is more stable than in O2 and H2O environments. This investigation enhanced the understanding of degradation of perovskite and provided some suggestions for developing more stable lead-free perovskite solar cells and devices.

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Publication details

The article was received on 05 Dec 2018, accepted on 04 Feb 2019 and first published on 06 Feb 2019

Article type: Paper
DOI: 10.1039/C8TA11705E
Citation: J. Mater. Chem. A, 2019, Accepted Manuscript

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    Insight into the reaction mechanism of water, oxygen and nitrogen molecule on the tin iodine perovskite surface

    G. Xie, L. Xu, L. Sun, Y. Xiong, P. Wu and B. Hu, J. Mater. Chem. A, 2019, Accepted Manuscript , DOI: 10.1039/C8TA11705E

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