Understanding liquefaction in halide perovskites upon methylamine gas exposure

Wencai Zhou, Zilong Zheng, Yue Lu, Manling Sui, Jun Yin, Hui Yan

Research output: Journal article publicationJournal articleAcademic researchpeer-review


Methylamine (CH3NH2, MA) gas-induced fabrication of organometal CH3NH3PbI3based perovskite thin films are promising photovoltaic materials that transform the energy from absorbed sunlight into electrical power. Unfortunately, the low stability of the perovskites poses a serious hindrance for further development, compared to conventional inorganic materials. The solid-state perovskites are liquefied and recrystallized from CH3NH2. However, the mechanism of this phase transformation is far from clear. Employing first principles calculations andab initiomolecular dynamics simulations, we investigated the formation energy of primary defects in perovskites and the liquefaction process in CH3NH2vapor. The results indicated that defect-assisted surface dissolution leads to the liquefaction of perovskite thin films in CH3NH2vapor. Two primary defects were studied: one is the Frenkel pair defect (including both negatively charged interstitial iodide ion (Ii) and iodide vacancy (VI+) at the PbI2-termination surface, and the other is the Schottky defects (methylammonium vacancy, VMA) at the MAI-termination surface. Moreover, the defect-induced disorder in the microstructure reduces the degeneration of energy levels, which leads to a blue shift and broader absorption band gap, as compared to the clean perovskite surface. The mechanism of how defects impact the surface dissolution could be applied for the further design of high-stability perovskite solar cells.

Original languageEnglish
Pages (from-to)20423-20428
Number of pages6
JournalRSC Advances
Issue number33
Publication statusPublished - 8 Jun 2021

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)


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