Ultrafast Excited-State Transport and Decay Dynamics in Cesium Lead Mixed Halide Perovskites
Ultrafast Excited-State Transport and Decay Dynamics in Cesium Lead Mixed Halide Perovskites
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DOI：
10.1021/acsenergylett.7b00257
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发表时间：
2017-07-01
影响因子：
22
通讯作者：
Grumstrup, Erik M.
中科院分区：
文献类型：
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作者：
Kennedy, Casey L.;Hill, Andrew H.;Grumstrup, Erik M.
虽然针对表征卤化铅钙钛矿的激发态动力学的重大研究努力已经使光伏、发光二极管和激光技术取得了有希望的进展，但这类有希望的材料中的组成和功能之间的详细相关性仍未建立。我们使用泵浦-探测显微镜来表征CsPbl（2）Br的单个晶体中的传输和弛豫动力学，CsPbl（2）Br是一种混合卤化物，与研究良好的有机-无机混合钙钛矿的全无机类似物。与甲基铵三碘化铅钙钛矿相反，我们发现激发态动力学主要通过一阶和俄歇机制衰减。通过对从各个区域收集的功率依赖动力学的全局拟合，我们发现俄歇速率常数在3.3 × 10（-30）和1.5 × 10（-28）cm（6）/s之间，二级（双分子）过程的贡献可以忽略不计。激发态空间演化的直接成像显示平均扩散常数为0.27 cm（2）/s，这个值比单晶有机-无机类似物的扩散常数小近一个数量级。
While significant research efforts directed toward characterizing the excited-state dynamics of lead halide perovskites have enabled promising advances in photovoltaic, light-emitting diode, and laser technologies, a detailed correlation between composition and functionality in this promising class of materials remains unestablished. We use pump-probe microscopy to characterize both transport and relaxation dynamics in individual crystals of CsPbl(2)Br, a mixed halide, all-inorganic analogue to the well-studied organic-inorganic hybrid perovskites. In contrast to the methylammonium lead tri-iodide perovskite, we find excited-state dynamics that decay primarily via first-order and Auger mechanisms. By global fitting of power-dependent kinetics collected from individual domains, we find a range of Auger rate constants between 3.3 x 10(-30) and 1.5 X 10(-28) cm(6)/s, with negligible contributions from second order (bimolecular) processes. Direct imaging of the excited-state spatial evolution reveals an average diffusion constant of 0.27 cm(2)/s, a value that is nearly an order of magnitude smaller than that of single-crystal, organic-inorganic analogues.