title: Ionic and Optical Properties of Methylammonium Lead Iodide Perovskite across the Tetragonal-Cubic Structural Phase Transition.
abstract: Practical hybrid perovskite solar cells (PSCs) must endure temperatures above the tetragonal-cubic structural phase transition of methylammonium lead iodide (MAPbI3). However, the ionic and optical properties of MAPbI3in such a temperature range, and particularly, dramatic changes in these properties resulting from a structural phase transition, are not well studied. Herein, we report a striking contrast at approximately 45 °C in the ionic/electrical properties of MAPbI3owing to a change of the ion activation energy from 0.7 to 0.5 eV, whereas the optical properties exhibit no particular transition except for the steady increase of the bandgap with temperature. These observations can be explained by the "continuous" nature of perovskite phase transition. We speculate that the critical temperature at which the ionic/electrical properties change, although related to crystal symmetry variation, is not necessarily the same temperature as when tetragonal-cubic structural phase transition occurs.
authors: Department of Electrical and Computer Engineering and Nano Tech Center, Texas Tech University, Lubbock, Texas, 79409, USA.
authors: Md Nadim Ferdous
authors: MN
authors: Hoque
authors: Department of Electrical and Computer Engineering and Nano Tech Center, Texas Tech University, Lubbock, Texas, 79409, USA.
authors: Nazifah
authors: N
authors: Islam
authors: Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado, 80401, USA.
authors: Zhen
authors: Z
authors: Li
authors: Department of Electrical and Computer Engineering and Nano Tech Center, Texas Tech University, Lubbock, Texas, 79409, USA.
authors: Guofeng
authors: G
authors: Ren
authors: Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado, 80401, USA. kai.zhu@nrel.gov.
authors: Kai
authors: K
authors: Zhu
authors: Department of Electrical and Computer Engineering and Nano Tech Center, Texas Tech University, Lubbock, Texas, 79409, USA. zhaoyang.fan@ttu.edu.
authors: Zhaoyang
authors: Z
authors: Fan
mesh_terms: D004355:Drug Stability; D004553:Electric Conductivity; D007454:Iodides / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D008744:Methylamines / Q000737:chemistry*; D055620:Optical Phenomena; D044367:Phase Transition; D013696:Temperature
chemical_list: D007454:Iodides; D008744:Methylamines; D007854:Lead; C027451:methylamine
keywords: cubic; optoelectronic properties; perovskite; phase transition; tetragonal