Hot carriers in mixed Pb-Sn halide perovskite semiconductors cool slowly while retaining their electrical mobility
Hot carriers in mixed Pb-Sn halide perovskite semiconductors cool slowly while retaining their electrical mobility
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DOI：
10.1103/physrevb.102.245204
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发表时间：
2020-12-24
影响因子：
3.7
通讯作者：
Lloyd-Hughes, James
中科院分区：
文献类型：
--
作者：
Monti, Maurizio;Jayawardena, K. D. G. Imalka;Lloyd-Hughes, James
电子-声子相互作用控制金属卤化物钙钛矿中电荷的固有迁移率，并决定载流子失去能量的速率。在这里，使用超快瞬态吸收光谱和光泵、太赫兹探针光谱的组合，在不同铅和锡含量的钙钛矿中以及一系列载流子密度下直接检查载流子迁移率和冷却动力学。值得注意的是，“热声子瓶颈”状态下的载流子迁移率（其中 LO 声子浴使载流子保持温暖）被发现与冷载流子的迁移率相似。开发了一个模型，可以定量描述实验载体冷却动力学，包括电子-声子耦合、声子-声子耦合和俄歇机制。在 Pb 和 Sn 合金中，由于光学声子的衰减较慢，热载流子状态的持续时间延长了。这些发现提供了宏观特性与潜在的微观能量转移过程之间的直观联系，并提出了控制金属卤化物钙钛矿载流子冷却过程以优化光电器件的新途径。
The electron-phonon interaction controls the intrinsic mobility of charges in metal halide perovskites, and determines the rate at which carriers lose energy. Here, the carrier mobility and cooling dynamics were directly examined using a combination of ultrafast transient absorption spectroscopy and optical pump, THz probe spectroscopy, in perovskites with different lead and tin content, and for a range of carrier densities. Significantly, the carrier mobility in the "hot phonon bottleneck" regime, where the LO phonon bath keeps carriers warm, was found to be similar to the mobility of cold carriers. A model was developed that provides a quantitative description of the experimental carrier cooling dynamics, including electron-phonon coupling, phonon-phonon coupling and the Auger mechanism. In the Pb and Sn alloy the duration of the hot carrier regime was extended as a result of the slower decay of optical phonons. The findings offer an intuitive link between macroscopic properties and the underlying microscopic energy transfer processes, and suggest new routes to control the carrier cooling process in metal halide perovskites to optimize optoelectronic devices.