Exciton-phonon interaction in quasi-two dimensional layered (PEA)2(CsPbBr3)n-1PbBr4 perovskite
Exciton-phonon interaction in quasi-two dimensional layered (PEA)2(CsPbBr3)n-1PbBr4 perovskite
复制标题
准二维层状(PEA)(2)(CsPbBr3)(n-1)PbBr4钙钛矿中激子-声子相互作用
DOI：
10.1039/c9nr06834a
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发表时间：
2019-12-07
期刊：
影响因子：
6.7
通讯作者：
Wei, Zhanhua
中科院分区：
文献类型：
--
作者：
Long, Hao;Peng, Xiang;Wei, Zhanhua
具有大体积有机阳离子的二维Ruddlesden-Popper钙钛矿结构由于其环境稳定性好、发光颜色可调、激子结合能力强、发光效率高等优点，在发光器件和光化学领域受到了广泛的关注。通过将PbBr 4层嵌入大体积有机阳离子中自发形成量子阱（QW）结构。然而，这些材料中的一些内在激子机制仍需要阐明。采用变温光致发光（PL）、扫描电子显微镜（SEM）和粉末X射线衍射（PXRD）研究了不同PbBr 4层数（n）的准二维（PEA）（2）（CsPbBr 3）（n-1）PbBr 4的激子-声子相互作用。在大n二维和体相钙钛矿中，禁带宽度随温度变化的机制主要是热膨胀效应，而在n = 1（PEA）（2）PbBr 4相中，禁带宽度随温度变化的机制逐渐转变为激子-声子相互作用，表明在较薄的量子阱结构中激子-声子相互作用增强.进一步的分析表明，激子-声子相互作用的增强源于纵向光学声子-激子Frohlich相互作用，而不是声学声子-激子耦合。我们相信，我们的研究结果将有利于进一步优化基于二维钙钛矿的发光器件。
Two-dimensional (2D) Ruddlesden-Popper perovskites with bulky organic cations have attracted extensive attention in light-emitting devices and photovoltaics due to their robust environment stability, tunable luminescent color, strong exciton binding and promising efficiency. A quantum well (QW) structure is spontaneously formed by sandwiching PbBr4 layers into bulky organic cations. However, some intrinsic excitonic mechanisms in these materials still need to be elucidated. In this study, the exciton-phonon interaction of quasi-2D (PEA)(2)(CsPbBr3)(n-1)PbBr4 with different PbBr4 layer numbers (n) was analyzed by temperature-varied photoluminescence (PL), scanning electron microscopy (SEM) and powder X-ray diffraction (PXRD). The mechanism of bandgap shifting with temperature was found to be dominated by the thermal expansion effect in the large-n 2D and bulk perovskite, and gradually switched to exciton-phonon interaction in the n = 1 (PEA)(2)PbBr4 phase, indicating enhanced exciton-phonon interaction in the thinner quantum well structure. Further analysis showed that the enhanced exciton-phonon interaction originated from the longitudinal optical phonon-exciton Frohlich interaction rather than acoustic phonon-exciton coupling. We believe that our results will benefit the further optimization of light-emitting devices based on 2D perovskites.