Exciton-Phonon and Trion-Phonon Couplings Revealed by Photoluminescence Spectroscopy of Single CsPbBr3 Perovskite Nanocrystals
Exciton-Phonon and Trion-Phonon Couplings Revealed by Photoluminescence Spectroscopy of Single CsPbBr3 Perovskite Nanocrystals
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DOI：
10.1021/acs.nanolett.2c02970
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发表时间：
2022-09-19
期刊：
影响因子：
10.8
通讯作者：
Kanemitsu, Yoshihiko
中科院分区：
文献类型：
--
作者：
Cho, Kenichi;Tahara, Hirokazu;Kanemitsu, Yoshihiko
卤化铅钙钛矿纳米晶具有优异的光致发光性能，在发光二极管和单光子源方面具有很好的应用前景。在这里，我们报告了单个CsPbBr 3 NCs低温PL光谱中源自激子、三重子和双激子的多峰结构。我们发现，精细结构分裂的PL峰的明亮的激子和双激子，也在激子的半导体光学（LO）-声子副本。在强光激发下，可以清楚地观察到三振子的LO声子复制品，但没有显示出精细结构分裂。从这些副本的尺寸依赖性分析，我们澄清，激子-声子和trion-声子耦合变得更大的较小的NC和trion的耦合强度大于激子在大NC。这些行为可以用纳米碳中电子和空穴波函数的空间分布来解释。我们的研究结果提供了必要的信息，在钙钛矿的电子-声子耦合和高纯度的单光子源的设计。
Lead halide perovskite nanocrystals (NCs) have outstanding photoluminescence (PL) properties and excellent potential for light-emitting diodes and single-photon sources. Here, we report the multiple-peak structures originating from excitons, trions, and biexcitons in low-temperature PL spectra of single CsPbBr3 NCs. We found fine-structure splitting in the PL peaks of bright excitons and biexcitons and also in the longitudinal-optical (LO)-phonon replicas of excitons. LO-phonon replicas of trions are clearly observed under strong photoexcitation, which do not show fine-structure splitting. From size-dependent analyses of these replicas, we clarified that both exciton-phonon and trion-phonon couplings become larger for smaller NCs and the coupling strengths of trions are larger than those of excitons in large NCs. These behaviors can be explained by the spatial distributions of the electron and hole wave functions in the NCs. Our findings provide essential information on electron-phonon couplings in perovskites and for the design of high-purity single-photon sources.