Many-body interactions in two-dimensional halide perovskites: exciton-electron complexes & electron-phonon coupling

研究界对无机-有机钙钛矿的广泛兴趣是由可以在这类材料中形成的丰富多样的纳米结构所推动的。它们特殊的化学可调性和结构多样性为探索有趣的新现象和应用的额外功能提供了有前途的途径。这个家族的一个重要成员是二维（2D）Ruddlesden-Popper化合物。2D钙钛矿有望加速寻求改善光电器件的稳定性和性能，为高效光伏和发光应用提供潜力，并作为探索和最终调整凝聚态多体物理的理想平台。它激发了概念科学调查方面的光电性能，由于特别强的相互作用和汇合的各种影响，发生在多个时间尺度上，在这些系统中发挥了重要作用。因此，关键的材料特性基本上植根于我们计划在拟议的研究中探索并最终控制的多粒子物理学。我们的项目的主要目标是获得基本的洞察耦合的电子和振动激发在2D钙钛矿的性质。我们的目标是全面了解二维钙钛矿中激子和自由载流子系统之间的相互作用，研究激子-电子混合物对光激发的能量结构及其输运行为的影响。将建立可靠的实验和理论协议，以确定结构复杂的2D钙钛矿的电子，激子和声子-声子耦合的基本作用及其对技术相关性能的影响。最后，我们将通过结合自由载流子密度的外部控制，电门控和化学合成策略来实现先进的概念来调整这些耦合现象，以合理改善2D钙钛矿的光电性能。为了实现这些目标，我们将把最先进的材料制造与基于时间分辨显微镜的先进实验技术相结合，并将其与高水平的理论方法相结合，用于研究电子，光学和振动特性及其相互作用。工作方案中详细概述的拟议科学议程旨在解决一个迅速发展的研究领域前沿的专题问题。结合实验和理论的努力将使我们能够成功地追求这些目标，实现混合钙钛矿半导体广泛领域的关键科学和技术进步。

The broad interest of the research community in inorganic-organic perovskites is fueled by a rich variety of nanostructures that can be formed within this class of materials. Their exceptional chemical tunability and structural diversity offer promising pathways to explore intriguing new phenomena and additional functionalities for applications. A prominent member of this family are two-dimensional (2D) Ruddlesden-Popper compounds. 2D perovskites promise to accelerate the search for improved stability and performance of optoelectronic devices, offer potential for high-efficiency photovoltaic and light-emitting applications, and serve as ideal platform to explore and ultimately tune many-body physics in condensed matter. It motivates conceptual scientific investigations in regard to their optoelectronic properties due to particularly strong interactions and a confluence of various effects that occur on multiple time-scales, playing a major role in these systems. Consequently, key material properties are essentially rooted in many-particle physics that we plan to explore and ultimately control in the proposed research. The main goal of our project is to gain fundamental insight into the nature of coupled electronic and vibrational excitations in 2D perovskites. We aim to develop a comprehensive understanding of interactions between excitonic and free-carrier systems in 2D perovskites, studying the impact of exciton-electron mixtures on the energy structure of optical excitations and their transport behavior. Reliable experimental and theoretical protocols will be established in order to determine the fundamental role of the electron-, exciton- and phonon-phonon coupling for structurally complex 2D perovskites and their impact on technologically relevant properties. Finally, we will move towards realizing advanced concepts to tune these coupling phenomena by combining external control of free carrier densities, electrical gating, and chemical synthesis strategies towards rational improvement of optoelectronic properties of 2D perovskites. To address these goals, we will merge state-of-the art material fabrication with advanced experimental techniques based on time-resolved microscopy and with high-level theoretical methodology for investigations of electronic, optical, and vibrational properties as well as their interplay. The proposed scientific agenda, outlined in detail in the work programme, is aimed towards topical questions on the forefront of a rapidly growing research field. The combined experimental and theoretical efforts will allow us to successfully pursue these objectives towards key scientific and technological advances in the broad area of hybrid perovskite semiconductors.