Excitonic states in spatially confined molecular structures

空间受限分子结构中的激子态

• 批准号: 220480386
• 负责人: Professor Dr. Jens Pflaum
• 金额: --
• 依托单位: Lehrstuhl für Experimentelle Physik VI
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/220480386?language=en
• 关键词: Excitonic; states; spatially; confined; molecular

This project aims for investigation of the primary optical excitations and their dynamic behavior in crystalline structures made of molecular semiconductors. As a key issue we will analyze the influence of spatially confined excitation volumes and their interfaces on the excitonic states and their temporal evolution. For this purpose, long-range ordered monolayers as well as bulk single crystals with self-organized, epitaxial surface structures will be prepared of polyaromatic molecules, such as rubrene or perylene-derivatives, via sublimation. Thereafter, these samples will be structurally and optically characterized, the latter by photoluminescence measurements at micrometer lateral resolution. The essential information on the energetics of the excitonic states will be obtained by their spectral characterization and the relaxation dynamics as well as activation energies will be deduced as a function of lateral position and temperature in a range between 4 and 400 K. In case of crystalline layers we will address questions on the impact of the surface-tovolume-ratio as well as of the translational invariance at the interfaces on the localization and delocalization of optical excitations. Applying capping layers with different properties provides an additional degree of freedom to vary the structural and electronic interface characteristics in a controlled and reliable fashion and thus to study their influence. We will draw our attention on the energy position of optical excitations and the variation or even suppression of relaxation channels by the size of the excitation volume as well as by interfacial states. Extending those studies to microscopic surface structures on-top of molecular single crystals will reveal profound insights in the spatial anisotropy of the related phenomena. By means of the entire sets of data we intend to develop a detailed understanding of the optically excited states in crystalline molecular stacks and of their influence by geometrical boundary conditions. In the course of these studies not only the microscopic excitonic processes, such as singlet exciton fission, and their utilization in optoelectronic device concepts will be evaluated but also innovative structures with defined functionalities will be prepared. As a key topic, the combination of spatially confined excitation volumes and tailored boundaries will be utilized to couple single molecules to the local field distribution. By their modified emission characteristics we will establish an approach towards new functionalities, which are essential e.g. for the implementation of non-classical, single photon sources. To achieve the described objectives, a concerted approach by various partners comprising expertise on the subject of synthesis, ultrafast spectroscopy and theoretical modelling is inevitable. All these requirements are fulfilled and guaranteed by the applied research unit FOR1809.

本计画旨在研究分子半导体晶体结构中的初级光激发及其动力学行为。作为一个关键问题，我们将分析空间限制的激发体积和它们的界面上的激子态和它们的时间演化的影响。为此，长程有序的单层以及自组织的，外延表面结构的大块单晶将制备聚芳族分子，如红荧烯或苝衍生物，通过升华。此后，这些样品将结构和光学特性，后者通过光致发光测量在微米横向分辨率。激子态的能量学的基本信息将通过它们的光谱表征获得，并且弛豫动力学以及活化能将被推导为在4和400 K之间的范围内的横向位置和温度的函数。在晶体层的情况下，我们将解决的问题的影响，表面体积比以及在本地化和离域的光学激发的界面上的平移不变性。应用具有不同性质的覆盖层提供了额外的自由度，以受控和可靠的方式改变结构和电子界面特性，从而研究它们的影响。我们将提请我们注意的能量位置的光激发和变化，甚至抑制的激发体积的大小以及界面状态的弛豫通道。将这些研究扩展到分子单晶顶部的微观表面结构，将揭示相关现象的空间各向异性的深刻见解。通过整个数据集，我们打算开发一个详细的了解晶体分子堆栈中的光激发态和几何边界条件的影响。在这些研究过程中，不仅将评估微观激子过程，如单重态激子裂变及其在光电器件概念中的应用，而且还将制备具有定义功能的创新结构。作为一个关键的主题，空间限制的激发体积和定制的边界的组合将被用来耦合单分子的局部场分布。通过它们修改后的发射特性，我们将建立一种实现新功能的方法，这些功能对于实现非经典单光子源至关重要。为了实现所述目标，不可避免地需要各合作伙伴采取协调一致的方法，包括合成、超快光谱和理论建模方面的专业知识。所有这些要求都得到了应用研究单位FOR1809的满足和保证。

项目成果

Nonthermally activated exciton transport in crystalline organic semiconductor thin films

晶体有机半导体薄膜中的非热激活激子传输

• DOI: 10.1103/physrevb.89.201203
• 发表时间: 2014
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: A. K. Topczak;T. Roller;B. Engels;W. Brütting;J. Pflaum;S. Ruetzel;M. Diekmann;P. Nuernberger;C. Walter;B. Engels;T. Brixner
• 通讯作者: T. Brixner

Ultrafast Pathways of the Photoinduced Insulator–Metal Transition in a Low‐Dimensional Organic Conductor

• DOI: 10.1002/adma.201900652
• 发表时间: 2019-03
• 期刊: Advanced Materials
• 影响因子: 29.4
• 作者: B. Smit;Florian Hüwe;N. Payne;O. Olaoye;I. Bauer;J. Pflaum;M. Schwoerer;H. Schwoerer

Hybrid metal-organic nanocavity arrays for efficient light out-coupling.

用于高效光输出耦合的混合金属有机纳米腔阵列

• DOI: 10.1364/oe.25.006678
• 发表时间: 2017
• 期刊: Optics express
• 影响因子: 3.8
• 作者: V. Kolb;J. Pflaum
• 通讯作者: J. Pflaum