Molecular simulation of physical properties and preparation of CH3NH3PbI3
【Abstract】Molecular dynamics simulation WAs used to investigate the structure characteristics and mechanical properties, and to discuss the vapor deposition of MAPbI3 on the TiO2 substrate under a temperature of 300 K and three precursor compositions of PbI2:CH3NH3I = 1:2, 1:1 and 2:1, respectively. During the preparation processes, three polyhedral groups including PbI42− tetrahedra, PbI53− pyramids and PbI64− octahedra are produced. After their arrangements were classified and the distribution of CH3NH3+ cations was analyzed, the early CH3NH3PbI3 nuclei consisting of well-connected PbIx (x = 4, 5 or 6) polyhedral clusters and sufficient amounts of surrounding CH3NH3+ cations were identified. The influence on early nuclei from the precursor compositions of PbI2:CH3NH3I was discussed. The results show that the calculated values of elastic modulus is in good agreement with the experimental results. The PbI53− pyramids dominate over other polyhedral groups during the vapor deposition simulations. Meanwhile, even though the total amounts of polyhedra have a small dependence on the precursor compositions, the populations of the well-connected clusters and the early nuclei decrease rapidly with increasing the PbI2:CH3NH3I ratio. This is in consistent with the experimental finding that adding more CH3NH3I will optimize the device performance to some extent.
【Keywords】 hybrid perovskite; molecular simulation; crystallization; precursor composition; solar energy; vapor deposition;
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