Magnetic Resonance Tools for Solar Materials

用于太阳能材料的磁共振工具

• 批准号: 446281755
• 负责人: Professor Dr. Jan Behrends
• 金额: --
• 依托单位: Institut für Experimentalphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/446281755?language=en
• 关键词: Magnetic; Resonance; Tools; Solar; Materials

Spin processes are highly important for the efficiency of organic solar cells and light-emitting diodes, yet their role remains largely unexplored. Due to the weak spin-orbit coupling, organic materials possess strict spin-selection rules and the properties of photoexcited species can therefore vary drastically, depending on the particular spin configuration. In addition, over the last years there has been tremendous progress on the development of hybrid organic-inorganic perovskite based materials, which now enables the fabrication of optoelectronic devices with remarkable performance. It has been suggested that the spin degree of freedom is relevant for photo-physical processes in these materials as well. Thus, spin properties of excited states are actively investigated in very different contexts. In this project, which is a collaborative effort involving scientists from Paris (Université Paris-Sud), Versailles (Université Versailles Saint-Quentin), Grenoble (Institut Néel), Bayreuth (Universität Bayreuth [UBAT]) and Berlin (Freie Universität Berlin [FU Berlin]), we will focus on two aspects: singlet exciton fission where a singlet exciton splits into two triplet excitons of lower energy and spin-dependent processes in few layer hybrid-organic perovskites down to the monolayer limit. We will explore the use of broadband and time-resolved optically detected magnetic resonance (ODMR) spectroscopy as a powerful method to establish the microscopic nature of bi-exciton states with total spin S = 2 (quintets) formed through singlet fission. This will allow us to characterise the microscopic positions of bound triplets in bi-exciton states, the strength of their interaction, as well as their fluorescence spectrum and kinetic properties. The limits of the ODMR experiment will be pushed to single geminate triplet-pair detection in order to observe effects obscured in ensemble measurements. The detailed physical picture emerging from these experiments will serve as the basis for a quantitative molecular-level characterisation of the electronic structure parameters of bi-exciton states, which will be carried out within the framework of the project. The materials relevant for solar cells and up-conversion have a complex morphology which cannot be probed in macroscopic experiments on single crystals. We are thus planning to develop a microfluorescence-based ODMR experiment. This development will also allow probing spin-properties of Methylammonium lead halide, a promising solar cell material, in the almost unexplored limit of chemical vapour deposition grown monolayers and few layer single crystal flakes of micrometer sizes. All in all, the MARS project will develop original spin-sensitive methods to probe the properties of photo-excited states that appear in exciton fission systems and novel materials with broad impact on fundamental optoelectronics and its applications.

自旋过程对有机太阳能电池和发光二极管的效率非常重要，但它们的作用在很大程度上仍未被探索。由于弱自旋-轨道耦合，有机材料具有严格的自旋选择规则，因此根据特定的自旋构型，光激发物质的性质会发生巨大变化。此外，在过去几年中，有机-无机钙钛矿基杂化材料的发展取得了巨大进展，现在可以制造具有卓越性能的光电器件。有人提出，自旋自由度也与这些材料的光物理过程有关。因此，激发态的自旋性质在非常不同的背景下被积极地研究。在这个项目中，这是一个由来自巴黎大学（巴黎南方大学）、凡尔赛大学（凡尔赛圣昆丁大学）、格勒诺布尔（nsamei研究所）、拜罗伊特（Universität拜罗伊特[UBAT]）和柏林（自由Universität柏林[FU柏林]）的科学家共同努力的项目，我们将重点关注两个方面：单线态激子裂变，单线态激子分裂成两个低能量的三重态激子，以及在少数层混合有机钙钛矿中自旋依赖的过程，直到单层极限。我们将探索使用宽带和时间分辨光学探测磁共振（ODMR）光谱作为一种强大的方法来建立由单线态裂变形成的总自旋为S = 2的双激子态（五元态）的微观性质。这将使我们能够表征双激子状态下束缚三联体的微观位置，它们相互作用的强度，以及它们的荧光光谱和动力学性质。ODMR实验的极限将被推到单双态三对探测，以便观察在集合测量中被掩盖的效应。从这些实验中产生的详细物理图像将作为双激子状态电子结构参数定量分子水平表征的基础，这将在项目框架内进行。与太阳能电池和上转换相关的材料具有复杂的形态，无法在单晶上进行宏观实验。因此，我们正计划开发一种基于微荧光的ODMR实验。这一发展也将允许探测甲基卤化铅铵的自旋特性，这是一种很有前途的太阳能电池材料，在几乎未被探索的化学气相沉积的极限下生长单层和几层微米大小的单晶片。总而言之，MARS项目将开发原创的自旋敏感方法来探测出现在激子裂变系统和对基础光电子学及其应用具有广泛影响的新材料中的光激发态的特性。