Comparing the Cubic and Tetragonal Phases of MAPbI<sub>3</sub> at Room Temperature
Ariany Bonadio, Fernando P. Sabino, André L. M. Freitas, Marissol Rodrigues Felez, Gustavo M. Dalpian, J. A. Souza
Abstract
Stability and maintenance of the crystal structure are the main drawbacks of the application of organic–inorganic perovskites in photovoltaic devices. The Δ T = 62 K robust shift of the structural phase transition observed here allows us to conduct a comprehensive study at room temperature of the tetragonal versus cubic phase on MAPbI 3 . The absence of the shift in the cubic transition for all-inorganic CsPbI 3 samples confirms the importance of both orientation and dynamics of the organic cations. Our results provide a unique opportunity to evaluate the physical properties of both cubic and tetragonal phases of MAPbI 3 at the same temperature, eliminating different phonon effects as possible causes for different properties. Besides higher electrical resistivity, the perovskite cubic phase presents a faster charge carrier lifetime than the tetragonal phase and partial PL quenching, pointing toward increased trap-assisted nonradiative recombination. The light absorption coefficient in the cubic phase is larger than the absorption in the tetragonal phase in the green region.