Visualization of exciton transport in ordered and disordered molecular solids
Visualization of exciton transport in ordered and disordered molecular solids
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DOI：
10.1038/ncomms4646
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发表时间：
2014-04-01
影响因子：
16.6
通讯作者：
Bulovic, Vladimir
中科院分区：
文献类型：
--
作者：
Akselrod, Gleb M.;Deotare, Parag B.;Bulovic, Vladimir
以激子形式传输纳米级能量是光合作用和各种纳米结构光电子器件，如太阳能电池、发光二极管和激子晶体管运行的核心。尤其重要的是激子传输和纳米无序之间的关系，这是分子和纳米结构材料的定义特征。本文报道了分子晶体和无序薄膜中激子输运的空间、时间和光谱可视化。以四苯为原型分子晶体，成像显示激子的输运是通过随机漫步扩散进行的，当激子被捕获时，激子的输运转变为次扩散。通过控制薄膜的形貌，我们发现，随着无序度的增加，这种向亚扩散输运的转变发生得更早。结果表明，激子输运机制强烈依赖于纳米尺度的形貌，这对激子材料和器件的设计具有广泛的指导意义。
Transport of nanoscale energy in the form of excitons is at the core of photosynthesis and the operation of a wide range of nanostructured optoelectronic devices such as solar cells, light-emitting diodes and excitonic transistors. Of particular importance is the relationship between exciton transport and nanoscale disorder, the defining characteristic of molecular and nanostructured materials. Here we report a spatial, temporal and spectral visualization of exciton transport in molecular crystals and disordered thin films. Using tetracene as an archetype molecular crystal, the imaging reveals that exciton transport occurs by random walk diffusion, with a transition to subdiffusion as excitons become trapped. By controlling the morphology of the thin film, we show that this transition to subdiffusive transport occurs at earlier times as disorder is increased. Our findings demonstrate that the mechanism of exciton transport depends strongly on the nanoscale morphology, which has wide implications for the design of excitonic materials and devices.