Unraveling the Microstructure of Inorganic Halide Perovskites during Thermally Driven Phase Transition and Degradation

The microstructure of halide perovskites during thermallydrivenphase transition and degradation is difficult to probe because oftheir radiation-sensitive nature. Taking advantage of low dose insitu high-resolution transmission electron microscopy imaging, wedirectly observed the nucleation and growth process of the phase transitionfrom orthorhombic gamma-CsPbBr3 to cubic alpha-CsPbBr3 in nanoplates during heating. The normalization of (PbBr6)(4-) octahedra was observed, and phase transitionpathways (edge-to-center growth and island growth) were summarized.Phase fluctuation/recovery occurs during the phase transition process.In addition, the thermal degradation caused by high temperature wasinvestigated. Degradation occurs from the outer edge to the centerregion. This work provides a microscopic basis for the understandingof phase transition and its application in devices.

Automated summary

By utilizing low dose in situ high-resolution transmission electron microscopy imaging, we directly observed the nucleation and growth process of the phase transition from orthorhombic gamma-CsPbBr3 to cubic alpha-CsPbBr3 in nanoplates during heating. The normalization of (PbBr6)(4-) octahedra was observed, and phase transition pathways (edge-to-center growth and island growth) were summarized. Phase fluctuation/recovery occurs during the phase transition process. Additionally, we investigated the thermal degradation caused by high temperature, which was found to occur from the outer edge to the center region. This work provides a microscopic basis for the understanding of phase transition and its application in devices.