Thermal Stability of the Black Perovskite Phase in Cesium Lead Iodide Nanocrystals Under Humid Conditions
Thermal Stability of the Black Perovskite Phase in Cesium Lead Iodide Nanocrystals Under Humid Conditions
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DOI：
10.1021/acs.chemmater.9b03533
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发表时间：
2019-12-10
影响因子：
8.6
通讯作者：
Korgel, Brian A.
中科院分区：
文献类型：
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作者：
Thomas, Cherrelle J.;Zhang, Yangning;Korgel, Brian A.
由于其间接带隙，在室温下在室温下的平衡相（CSPBI3）在室温下是黄色的，光学不活跃。另一方面，CSPBI3的亚稳态黑色相具有适用于光伏和发光设备的光学性质。在这里，我们研究了在潮湿空气中加热的配体稳定的CSPBI3纳米晶体黑色相的稳定性。众所周知，水蒸气可以催化CSPBI3从黑相向黄相的过渡。将均匀的纳米晶体与立方体形状合成，并用含油胺和油酸的盖配体混合物或二辛基膦酸合成，并以优选的晶体取向组装成超级晶格，并使用放牧的小小的和广角X射线散射与现场热量进行研究。发现黑相纳米晶体居住在伽马 - 正骨相位，并且不会恢复到平衡的黄色三角形 - 正晶相，直到达到相对较高的温度，在170至200度C之间，与超级层次降解相吻合。
The equilibrium phase of cesium lead iodide (CsPbI3) at room temperature is yellow and optically inactive due to its indirect band gap. The metastable black phase of CsPbI3 on the other hand exhibits optical properties that are suitable for photovoltaic and light-emitting devices. Here, we examine the stability of the black phase of ligand-stabilized CsPbI3 nanocrystals heated in humid air. Water vapor is known to catalyze the transition of CsPbI3 from the black phase to the yellow phase. Uniform nanocrystals with cube shape were synthesized with capping ligand mixtures of oleylamine and oleic acid or diisooctylphosphinic acid, assembled into superlattices with preferred crystal orientation, and studied using grazing incidence small- and wide-angle X-ray scattering with in situ heating. The black-phase nanocrystals are found to inhabit the gamma-orthorhombic phase and do not revert to the equilibrium yellow delta-orthorhombic phase until reaching a relatively high temperature, between 170 and 200 degrees C, coinciding with superlattice degradation.