Investigation of intrinsic charge and spin transport mechanisms in organic molecules

有机分子中本征电荷和自旋输运机制的研究

• 批准号: EP/G054568/1
• 负责人: Alan Drew
• 金额: $ 33.16万
• 依托单位: Queen Mary University of London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FG054568%2F1
• 关键词: Investigation; intrinsic; charge; spin; transport

The importance and performance of organic electronic devices have increased significantly in the last two decades, and are increasingly showing great promise for new applications. Electronic devices based on organic semiconductors are revolutionising electroluminescent displays and large-area electronics, as they are economically favourable, can be easily processed into large areas and have tuneable electronic. Even though the mechanisms of charge transport in such organic conductors are fundamental to their operation, many aspects of organic charge transport are still only poorly understood and progress in this area may be pivotal to utilising these materials to their fullest extent. Furthermore, understanding the underlying physics of charge transport in bulk small-molecule organic semiconductors is critical to the emerging field of organic spintronics, but is extremely challenging, partly because it is not completely accessible using conventional experimental techniques.One particularly powerful class of techniques that can be used to measure charge carrier transport in organic materials makes use of a spin probe to measure spin fluctuations at a probe position. The spin probe techniques of electron spin resonance (ESR) and nuclear magnetic resonance (NMR) have been used to study carrier diffusion in anisotropic conductors, including doped conducting polymers. In contrast to ESR and NMR, muon spin relaxation (muSR) has the unique feature that in organic materials it can both generate an excitation by chemical reaction with the system and also act as a sensitive probe of the dynamics of this excitation. Thus, muSR spin dynamics is a particularly powerful probe for conductors with very low concentrations of carriers. Furthermore, as a result of the single-point nature of the spin probe, it is not affected by interface related effects and it is highly sensitive to intrinsic charge carrier transport at a molecular lengthscale, over a broad range of different morphologies, with different chemical structures and packing motifs. Since muSR is a spin probe it is also sensitive to the charge carrier's spin relaxation. It is thus unique in its ability to measure, at the same time in the same sample, the charge and spin dynamics on a molecular lengthscale. This allows one to perform the types of studies required to push back the fundamental understanding of charge carrier transport and spin processes in organic materials, which could be of extreme importance when developing the next generation of organic devices, whether using spin or charge based phenomena. This proposal's aim is threefold. Firstly, perform muSR measurements on a number of different technologically relevant metal-quinolates to provide a quantitative measurement of the upper limit of charge carrier mobility, and where possible, measure the electron spin relaxation rate. Secondly, perform muSR measurements on a series of different pentacene derivatives, where the motif, displacement and vibrational modes are all a dependent on the chemical structure of the functionalisation, the number of functional branches and the relative position of them on the backbone. Thirdly, develop the theoretical models to be able to interpret the muon results and extract quantitative physical parameters relevant for the device community.

有机电子器件的重要性和性能在过去二十年中显著增加，并且越来越显示出新应用的巨大前景。基于有机半导体的电子器件正在革新电致发光显示器和大面积电子器件，因为它们在经济上是有利的，可以容易地加工成大面积并且具有可调谐的电子器件。即使在这样的有机导体的电荷传输的机制是其操作的基础，有机电荷传输的许多方面仍然是知之甚少，在这一领域的进展可能是关键的，以充分利用这些材料。此外，理解体小分子有机半导体中电荷传输的基本物理对于有机自旋电子学的新兴领域至关重要，但极具挑战性，可以用于测量有机材料中的电荷载流子输运的一类特别强大的技术利用自旋探针来测量自旋涨落，探针位置。电子自旋共振（ESR）和核磁共振（NMR）自旋探针技术已被用于研究载流子在各向异性导体（包括掺杂导电聚合物）中的扩散。与ESR和NMR相比，μ子自旋弛豫（muSR）具有独特的功能，即在有机材料中，它既可以通过与系统的化学反应产生激发，也可以作为这种激发动力学的灵敏探针。因此，muSR自旋动力学是一个特别强大的探针导体具有非常低的载流子浓度。此外，作为自旋探针的单点性质的结果，它不受界面相关效应的影响，并且它对分子长度尺度上的本征电荷载流子输运高度敏感，在宽范围的不同形态上，具有不同的化学结构和填充图案。由于muSR是一种自旋探针，因此它对电荷载流子的自旋弛豫也很敏感。因此，它是独特的，在同一时间在同一样品中，在分子长度尺度上的电荷和自旋动力学测量的能力。这使得人们可以进行所需的研究类型，以推动对有机材料中电荷载流子传输和自旋过程的基本理解，这在开发下一代有机器件时可能非常重要，无论是使用基于自旋还是电荷的现象。这项建议有三个目的。首先，对许多不同的技术相关的金属喹啉化合物进行muSR测量，以提供电荷载流子迁移率上限的定量测量，并在可能的情况下测量电子自旋弛豫速率。其次，对一系列不同的并五苯衍生物进行muSR测量，其中基序、位移和振动模式都取决于官能化的化学结构、官能化分支的数量以及它们在主链上的相对位置。第三，发展理论模型，以便能够解释μ子结果并提取与器件社区相关的定量物理参数。

项目成果

Electronic and magnetic properties of the interface between metal-quinoline molecules and cobalt

• DOI: 10.1103/physrevb.89.094412
• 发表时间: 2014-03-12
• 期刊: PHYSICAL REVIEW B
• 影响因子: 3.7
• 作者: Droghetti, Andrea;Steil, Sabine;Cinchetti, Mirko
• 通讯作者: Cinchetti, Mirko

Electron spin relaxation in organic semiconductors probed through muSR

通过 muSR 探测有机半导体中的电子自旋弛豫

• DOI: 10.48550/arxiv.1006.4580
• 发表时间: 2010
• 作者: Nuccio L

Muon spin spectroscopy: magnetism, soft matter and the bridge between the two

μ子自旋光谱：磁性、软物质以及两者之间的桥梁

• DOI: 10.1088/0022-3727/47/47/473001
• 发表时间: 2014-11
• 期刊: Journal of Physics D: Applied Physics
• 作者: L Nuccio;L Schulz;A J Drew
• 通讯作者: A J Drew

The role of interfaces in organic spin valves revealed through spectroscopic and transport measurements

• DOI: 10.1002/pssb.201147157
• 发表时间: 2012-01
• 期刊: physica status solidi (b)
• 作者: A. Drew;G. Szulczewski;L. Nuccio;W. Gillin

Muon spin spectroscopy

• DOI: 10.1002/9783527809080.cataz11224
• 发表时间: 2020-04
• 期刊: Catalysis from A to Z
• 作者: P. Albers