二维（2D）和准二维锡基钙钛矿的飞秒激子与载流子弛豫动力学
Femtosecond Exciton and Carrier Relaxation Dynamics of Two-Dimensional (2D) and Quasi-2D Tin Perovskites.
作者信息
Narra Sudhakar, Lin Chia-Yi, Seetharaman Ashank, Jokar Efat, Diau Eric Wei-Guang
机构信息
Department of Applied Chemistry and Institute of Molecular Science, National Yang Ming Chiao Tung University, 1001 Ta-Hseuh Road, Hsinchu 30010, Taiwan.
Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, 1001 Ta-Hseuh Road, Hsinchu 30010, Taiwan.
出版信息
J Phys Chem Lett. 2021 Dec 30;12(51):12292-12299. doi: 10.1021/acs.jpclett.1c03427. Epub 2021 Dec 21.
The dynamics of exciton and free-carrier relaxation of low-dimensional tin iodide perovskites, BAFASnI, where = 1 (N1), 2 (N2), 5 (N5), and 10 (N10), were investigated with femtosecond transient absorption spectra (TAS). The absorption and photoluminescence spectra of N1 and N2 show exciton characteristics due to quantum confinement, whereas N5 and N10 display a free-carrier nature, the same as for bulk three-dimensional (3D) films. The TAS profiles were fitted according to a global kinetic model with three time coefficients representing the interactions of biexcitons, trions, and excitons for N1 and N2 and hot carriers, cold carriers, and shallow trap carriers for N5 and N10. The carrier relaxation dynamics of N5 and N10 were similar to those of 3D FASnI except for the absence of surface recombination in the deep-trap states due to passivation of the grain surfaces by the long alkyl chain for these quasi-2D samples (N5/N10 vs 3D).
利用飞秒瞬态吸收光谱（TAS）研究了低维碘化锡钙钛矿BAFASnI（其中 = 1（N1）、2（N2）、5（N5）和10（N10））的激子和自由载流子弛豫动力学。N1和N2的吸收光谱和光致发光光谱由于量子限制而呈现激子特性，而N5和N10则表现出自由载流子性质，与体相三维（3D）薄膜相同。根据全局动力学模型对TAS谱进行拟合，对于N1和N2，三个时间系数分别代表双激子、三重子和激子的相互作用；对于N5和N10，三个时间系数分别代表热载流子、冷载流子和浅陷阱载流子。N5和N10的载流子弛豫动力学与3D FASnI相似，只是由于这些准二维样品（N5/N10与3D相比）的长烷基链对晶粒表面的钝化作用，深陷阱态中不存在表面复合。
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