Interfacial-Field-Induced Increase of the Structural Phase Transition Temperature in Organic-Inorganic Perovskite Crystals Coated with ZnO Nanoshell

The hybrid organic-inorganic perovskites are known to exhibit a complex crystalline structure, which allows for the structural phase transitions among the orthorhombic, tetragonal, and cubic phases that occur at different temperatures. This behavior of the organic-inorganic perovskites can significantly alter their optoelectronic properties. Here, using photoluminescence spectroscopy, it is shown that the structural orthorhombic-to-tetragonal phase transition temperature in MAPbI(3) perovskite crystal can be increased from 135 to 160 K upon coating with ZnO nanoshell. The phenomenon is attributed to the interfacial-field-induced atomic rearrangement in the near-surface area. The findings shed light on the great importance of the interfacial electric field effect on the structural and optical properties of the organic-inorganic perovskites, which hold great promise for their potential applications in the structural-phase-controlled optoelectronic and photovoltaic devices.