Preserving a robust CsPbI₃ perovskite phase via pressure-directed octahedral tilt.

ABSTRACT: Functional CsPbI₃ perovskite phases are not stable at ambient conditions and spontaneously convert to a non-perovskite ? phase, limiting their applications as solar cell materials. We demonstrate the preservation of a black CsPbI₃ perovskite structure to room temperature by subjecting the ? phase to pressures of 0.1 - 0.6?GPa followed by heating and rapid cooling. Synchrotron X-ray diffraction and Raman spectroscopy indicate that this perovskite phase is consistent with orthorhombic ?-CsPbI₃. Once formed, ?-CsPbI₃ could be then retained after releasing pressure to ambient conditions and shows substantial stability at 35% relative humidity. First-principles density functional theory calculations indicate that compression directs the out-of-phase and in-phase tilt between the [PbI₆]^4- octahedra which in turn tune the energy difference between ?- and ?-CsPbI₃, leading to the preservation of ?-CsPbI₃. Here, we present a high-pressure strategy for manipulating the (meta)stability of halide perovskites for the synthesis of desirable phases with enhanced materials functionality.

SUBMITTER: Ke F 

PROVIDER: S-EPMC7815753 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature