Zhou Wei, Sui Fan, Zhong Guohua, Cheng Guanming, Pan Mingyue, Yang Chunlei, Ruan Shuangchen
Shenzhen Key Laboratory of Laser Engineering , College of Optoelectronic Engineering , Shenzhen University , Shenzhen 518060 , China.
Center for Photovoltaics and Solar Energy, Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , China.
J Phys Chem Lett. 2018 Sep 6;9(17):4915-4920. doi: 10.1021/acs.jpclett.8b02036. Epub 2018 Aug 16.
Cubic-phase CsPbI quantum dots (QDs) have been recently synthesized with merits of excellent optoelectronic performance. However, vital properties of cubic CsPbI including lattice dynamics and stability at high temperature remain poorly explored. We fabricate cubic CsPbI QDs and study their lattice dynamic and thermal stability to 700 K. We obtain Raman modes of cubic CsPbI QDs from 300 to 500 K at ultra-low-frequency range down to 15 cm, consistent with first-principles calculations. Above 550 K, the modification of Raman features suggests sample degradation. Consistently, temperature-dependent photoluminescence measurements indicate the absence of other luminescence phases up to 700 K. With increasing temperature, the CsPbI QD photoluminescence peak has a blue shift with exponentially decreasing intensity, showing faster electronic degradation than structural degradation. Our work provides detailed investigation of CsPbI QD lattice dynamics, band gap, and their high-temperature behavior, potentially useful for their emerging optoelectronic applications.
立方相CsPbI量子点（QDs）最近已被合成出来，具有优异的光电性能。然而，立方相CsPbI的重要性质，包括晶格动力学和高温稳定性，仍未得到充分探索。我们制备了立方相CsPbI量子点，并研究了它们的晶格动力学和高达700 K的热稳定性。我们在低至15 cm的超低频范围内获得了300至500 K的立方相CsPbI量子点的拉曼模式，这与第一性原理计算结果一致。在550 K以上，拉曼特征的变化表明样品发生了降解。同样，温度依赖的光致发光测量表明，在高达700 K时不存在其他发光相。随着温度升高，CsPbI量子点的光致发光峰发生蓝移，强度呈指数下降，表明电子降解比结构降解更快。我们的工作对CsPbI量子点的晶格动力学、带隙及其高温行为进行了详细研究，这可能对其新兴的光电应用有用。
