Subdiffusive Exciton Transport in Quantum Dot Solids
Subdiffusive Exciton Transport in Quantum Dot Solids
复制标题
DOI：
10.1021/nl501190s
复制
发表时间：
2014-06-01
期刊：
影响因子：
10.8
通讯作者：
Tisdale, William A.
中科院分区：
文献类型：
--
作者：
Akselrod, Gieb M.;Prins, Ferry;Tisdale, William A.
胶体量子点（QD）是用于太阳能电池、发光二极管、激光器和光电探测器的有前途的材料，但 QD 材料中激子传输的机制和长度尚不清楚。我们使用时间分辨光学显微镜对 CdSe/ZnCdS 核/壳 QD 组件中的激子传输进行空间可视化。我们发现，在某些情况下，激子扩散长度超过30 nm，可以通过调整无机壳厚度和有机配体长度来调节，为控制激子运动提供了强有力的策略。此外，我们通过实验和动力学蒙特卡罗模拟表明，QD 固体中的激子扩散并不是通过随机游走过程发生的；相反，不均匀加宽系综内的能量紊乱会导致激子扩散率随着时间的推移而降低。这些发现揭示了对无序系统中激子动力学的新见解，并证明了量子点材料在光子和光电应用中的灵活性。
Colloidal quantum dots (QDs) are promising materials for use in solar cells, light-emitting diodes, lasers, and photodetectors, but the mechanism and length of exciton transport in QD materials is not well understood. We use time-resolved optical microscopy to spatially visualize exciton transport in CdSe/ZnCdS core/shell QD assemblies. We find that the exciton diffusion length, which exceeds 30 nm in some cases, can be tuned by adjusting the inorganic shell thickness and organic ligand length, offering a powerful strategy for controlling exciton movement. Moreover, we show experimentally and through kinetic Monte Carlo simulations that exciton diffusion in QD solids does not occur by a random-walk process; instead, energetic disorder within the inhomogeneously broadened ensemble causes the exciton diffusivity to decrease over time. These findings reveal new insights into exciton dynamics in disordered systems and demonstrate the flexibility of QD materials for photonic and optoelectronic applications.