Centre for Surface Chemistry and Catalysis, KU Leuven, Celestijnenlaan 200F, Leuven 3001, Belgium.
Department of Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven 3001, Belgium.
Science. 2019 Aug 16;365(6454):679-684. doi: 10.1126/science.aax3878. Epub 2019 Jul 25.
The high-temperature, all-inorganic CsPbI perovskite black phase is metastable relative to its yellow, nonperovskite phase at room temperature. Because only the black phase is optically active, this represents an impediment for the use of CsPbI in optoelectronic devices. We report the use of substrate clamping and biaxial strain to render black-phase CsPbI thin films stable at room temperature. We used synchrotron-based, grazing incidence, wide-angle x-ray scattering to track the introduction of crystal distortions and strain-driven texture formation within black CsPbI thin films when they were cooled after annealing at 330°C. The thermal stability of black CsPbI thin films is vastly improved by the strained interface, a response verified by ab initio thermodynamic modeling.
高温、全无机 CsPbI 钙钛矿黑相在室温下相对于其黄相、非钙钛矿相是亚稳态的。由于只有黑相在光学上是活性的，这代表了 CsPbI 在光电设备中使用的障碍。我们报告了使用衬底夹和双轴应变来使室温下的黑相 CsPbI 薄膜稳定。我们使用基于同步加速器的掠入射广角 X 射线散射来跟踪在 330°C 退火后冷却时黑 CsPbI 薄膜中晶体变形和应变驱动织构形成的引入。应变界面极大地提高了黑 CsPbI 薄膜的热稳定性，这一响应通过第一性原理热力学模拟得到了验证。
