Lai Runchen, Yang Zhangqiang, Zhi Chongyang, Cao Xuhui, Li Zhen, Di Dawei, Yang Ye
State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou 310027, China.
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
J Phys Chem Lett. 2022 Jun 23;13(24):5488-5494. doi: 10.1021/acs.jpclett.2c01453. Epub 2022 Jun 10.
In lead halide perovskites, owing to the strong Fröhlich coupling, carrier dynamics that governs the optoelectronic performance is greatly affected by the lattice vibrations. In this emerging class of materials, injected hot carriers quickly relax by emitting optical phonons, and if this process is sufficiently fast, hot optical phonons can be generated, which may in turn hamper the carrier transport. However, the transient interaction between hot phonons and carriers has not yet been investigated. Herein, we identified the transient absorption feature of hot phonons in lead bromide perovskites and then extracted the hot-phonon dynamics. The hot-phonon decay mechanism was uncovered by temperature-dependent measurements. The hot-phonon decay in lead bromide perovskites was an order of magnitude faster than that in GaAs, attributed to the large anharmonicity arising from the lattice softness and structural fluctuation. The carrier mobility was also transiently suppressed by hot phonons, and the mobility recovery was accompanied by the decay of hot phonons.
在卤化铅钙钛矿中，由于存在强弗罗利希耦合，支配光电性能的载流子动力学受到晶格振动的极大影响。在这类新兴材料中，注入的热载流子通过发射光学声子迅速弛豫，如果这个过程足够快，就会产生热光学声子，这反过来可能会阻碍载流子传输。然而，热声子与载流子之间的瞬态相互作用尚未得到研究。在此，我们确定了溴化铅钙钛矿中热声子的瞬态吸收特征，然后提取了热声子动力学。通过温度相关测量揭示了热声子的衰减机制。溴化铅钙钛矿中的热声子衰减比砷化镓中的快一个数量级，这归因于晶格柔软性和结构波动引起的大非谐性。热声子也会瞬时抑制载流子迁移率，迁移率的恢复伴随着热声子的衰减。
