School of Chemistry, University of Glasgow, Glasgow, UK.
Department Chemie and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, München, Germany.
Nat Commun. 2021 Feb 26;12(1):1327. doi: 10.1038/s41467-021-21474-z.
The particle-like nature of light becomes evident in the photon statistics of fluorescence from single quantum systems as photon antibunching. In multichromophoric systems, exciton diffusion and subsequent annihilation occurs. These processes also yield photon antibunching but cannot be interpreted reliably. Here we develop picosecond time-resolved antibunching to identify and decode such processes. We use this method to measure the true number of chromophores on well-defined multichromophoric DNA-origami structures, and precisely determine the distance-dependent rates of annihilation between excitons. Further, this allows us to measure exciton diffusion in mesoscopic H- and J-type conjugated-polymer aggregates. We distinguish between one-dimensional intra-chain and three-dimensional inter-chain exciton diffusion at different times after excitation and determine the disorder-dependent diffusion lengths. Our method provides a powerful lens through which excitons can be studied at the single-particle level, enabling the rational design of improved excitonic probes such as ultra-bright fluorescent nanoparticles and materials for optoelectronic devices.
光的粒子性质在单量子系统的荧光光子统计中表现明显，呈现出光子反聚束现象。在多发色团系统中，激子扩散和随后的湮灭会发生。这些过程也会产生光子反聚束，但无法可靠地解释。在这里，我们开发了皮秒时间分辨反聚束技术来识别和解码这些过程。我们使用这种方法来测量定义明确的多发色团 DNA 折纸结构上的真实发色团数量，并精确确定激子之间距离相关的湮灭速率。此外，这使我们能够测量介观 H 型和 J 型共轭聚合物聚集体中的激子扩散。我们在激发后不同时间区分一维链内和三维链间激子扩散，并确定与无序相关的扩散长度。我们的方法提供了一个强大的镜头，通过这个镜头可以在单粒子水平上研究激子，从而能够合理设计改进的激子探针，如超亮荧光纳米粒子和光电设备材料。
