Lin Cheng-Chieh, Huang Shao-Ku, Hsu Chung-En, Huang Yu-Chen, Wei Chuan-Yu, Wen Cheng-Yen, Li Shao-Sian, Chen Chun-Wei, Chen Chia-Chun
International Graduate Program of Molecular Science and Technology, National Taiwan University and Taiwan International Graduate Program, Academia Sinica, Taipei 10617, Taiwan.
Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan.
J Phys Chem Lett. 2020 May 7;11(9):3287-3293. doi: 10.1021/acs.jpclett.0c00443. Epub 2020 Apr 14.
Perovskite α-CsPbI nanocrystals (NCs) with a high fluorescence quantum yield (QY) typically undergo a rapid phase transformation to a low-QY δ-CsPbI phase, thus limiting their optoelectronic applications. In this study, organic molecule hexamethyldisilathiane (HMS) is used as a unique surfactant to greatly enhance the stability of the cubic phase of CsPbI NCs (HMS-CsPbI) under ambient conditions. The reaction kinetics of the phase transformation of CsPbI NCs are systemically investigated through in situ photoluminescence (PL), X-ray diffraction, and transmission electron microscope (TEM) measurements under moisture. The activation energy of HMS-CsPbI NCs is found to be 14 times larger than that of CsPbI NCs capped by olyelamine (OLA-CsPbI NCs). According to density functional theory calculations, the bonding between HMS and CsPbI NCs is stronger than that between OLA and CsPbI NCs, preventing the subsequent phase transformation. Our study presents a clear pathway for achieving highly stable CsPbI NCs for future applications.
具有高荧光量子产率（QY）的钙钛矿α-CsPbI纳米晶体（NCs）通常会迅速相转变为低QY的δ-CsPbI相，从而限制了它们的光电应用。在本研究中，有机分子六甲基二硅硫烷（HMS）被用作一种独特的表面活性剂，以在环境条件下极大地增强CsPbI NCs（HMS-CsPbI）立方相的稳定性。通过在湿度条件下的原位光致发光（PL）、X射线衍射和透射电子显微镜（TEM）测量，系统地研究了CsPbI NCs相转变的反应动力学。发现HMS-CsPbI NCs的活化能比由聚乙撑亚胺包覆的CsPbI NCs（OLA-CsPbI NCs）大14倍。根据密度泛函理论计算，HMS与CsPbI NCs之间的键合比OLA与CsPbI NCs之间的键合更强，从而防止了随后的相转变。我们的研究为实现未来应用中高度稳定的CsPbI NCs提供了一条清晰的途径。
