Qin Liang, Wen Zhilin, Zhang Xiaoxian, Zhang Ke, Lin Yunxiang, Song Li, Wu Xiaojun, Qiu Xiaohui
CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P.R. China.
University of Chinese Academy of Sciences, Beijing 100049, P.R. China.
J Phys Chem Lett. 2020 Oct 15;11(20):8483-8489. doi: 10.1021/acs.jpclett.0c02530. Epub 2020 Sep 23.
The interaction between photogenerated carriers with lattice vibrations plays a fundamental role in the nonradiative recombination and charge-transfer processes occurring in photocatalysis and photovoltaics. Here, we employ Raman spectroscopy to investigate the electron-phonon interaction in ternary layered CuMoS nanoflakes. Multiphonon Raman scattering with up to fourth-order longitudinal optical (LO) overtones is observed under above-band gap excitation, indicating a strong electron-phonon coupling (EPC) that could be described by the cascade model. The Huang-Rhys factor was derived to characterize the strength of EPC and was found to be increasing with decreasing temperature. First-principles calculations of lattice dynamics and electron-phonon matrix elements suggest that the strong EPC in CuMoS is dominated by Fröhlich coupling between electron and the electric fields, which is induced by the localized phonon mode originating from a flat phonon branch. Our findings facilitate the understanding of electron-phonon interaction in 2D ternary CuMoS and pave the way for developing and optimizing optoelectronic devices.
光生载流子与晶格振动之间的相互作用在光催化和光伏中发生的非辐射复合及电荷转移过程中起着根本性作用。在此，我们采用拉曼光谱来研究三元层状CuMoS纳米片的电子 - 声子相互作用。在带隙以上激发下观察到了高达四阶纵向光学（LO）泛音的多声子拉曼散射，这表明存在一种可由级联模型描述的强电子 - 声子耦合（EPC）。推导出了黄 - 里斯因子来表征EPC的强度，并且发现其随温度降低而增加。晶格动力学和电子 - 声子矩阵元的第一性原理计算表明，CuMoS中的强EPC由电子与电场之间的弗罗利希耦合主导，该耦合由源自平坦声子分支的局域声子模式诱导产生。我们的研究结果有助于理解二维三元CuMoS中的电子 - 声子相互作用，并为开发和优化光电器件铺平了道路。
