Investigation of materials and devices for organic photovoltaics by EPR and EDMR

通过 EPR 和 EDMR 研究有机光伏材料和器件

• 批准号: 2604988
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2604988
• 关键词: Investigation; materials; devices; organic; photovoltaics

This research project will study fundamental processes in materials and devices for organic photovoltaic systems through investigation by EPR (Electron Paramagnetic Resonance) and EDMR (Electrically Detected Magnetic Resonance) spectroscopy. It primarily falls within the EPSRC Analytical Science and Materials for Energy Applications research areas within the Physical Sciences theme and has practical applications to the Energy theme as well.Organic photovoltaic systems involve a blend of donor and acceptor molecules that, after excitation by light, form singlet excitons that can then dissociate into a spin-correlated radical pair by charge transfer at a donor-acceptor interface. This radical pair is characterised by coupled unpaired electron spins that can be detected by EPR spectroscopy. Efficient charge separation over recombination of the radical pair is critical for an effective organic photovoltaic system.In the past, EPR and EDMR spectroscopy have been used to investigate a range of different spin centres in silicon solar cells and in fullerene-based organic solar cells. Currently, research in organic photovoltaics is focused on non-fullerene acceptors that have led to increased energy conversion efficiencies. Photovoltaic cells based on non-fullerene acceptors have been showing tremendous growth in efficiency in the last decade at a much faster rate than similar fullerene-based acceptors. Since EPR and EDMR can follow the evolution from a charge-transfer state to separated charges, the aim of the project is to use these methods to gain a better insight into this process for donor- acceptor blends including state-of-the-art non-fullerene acceptors. Different continuous-wave and pulse EPR and EDMR experiments will be used to characterise the nature and dynamics of the spin centres in materials for organic photovoltaics. In particular, the interactions of the spin centres with their molecular environment, including hyperfine interactions to nearby magnetic nuclei and dipolar and exchange interactions between spin centres, will be investigated using advanced pulse EPR and EDMR techniques. The aim is to gain molecular-level insight into the charge separation, recombination, and transport processes relevant for solar cell operation and to identify molecular requirements for efficient energy conversion. Recent developments in digital electronics have enabled the integration of shaped pulses into pulse EPR sequences. Compared to traditional rectangular pulses, shaped pulses allow increased spin control and the design of new experiments with increased sensitivity and with increased accuracy in the characterisation of magnetic interactions. Shaped pulses have been demonstrated to achieve increased sensitivity for structural characterisation of biological systems by EPR but have so far not been used to aid the investigation of spin centres in materials for organic electronics. This project will involve development of EPR experiments tailored to exploit the advantages of shaped pulses in the characterisation of spins in these materials. Within EDMR, the use of shaped pulses is currently still largely unexplored, therefore, this project will also aim to develop the pulse EDMR method further through the inclusion of shaped pulses and the design of novel pulse sequences that leverage the increased spin control they provide. This project, at the interface of physics, chemistry, and materials science, is aligned with the EPSRC's focus on interdisciplinarity in research. The insights gained from EPR and EDMR spectroscopy on the fundamental processes involved in the conversion of solar energy to electricity in organic photovoltaics will have great significance for the field of solar energy technology. The developed methods and approaches are additionally relevant to many other research areas within the Physical Sciences theme, including optoelectronics, spintronics and quantum computing.

该研究项目将通过EPR（电子顺磁共振）和EDMR（电检测到的磁共振）光谱研究来研究有机光伏系统材料和设备的基本过程。 It primarily falls within the EPSRC Analytical Science and Materials for Energy Applications research areas within the Physical Sciences theme and has practical applications to the Energy theme as well.Organic photovoltaic systems involve a blend of donor and acceptor molecules that, after excitation by light, form singlet excitons that can then dissociate into a spin-correlated radical pair by charge transfer at a donor-acceptor interface.这种自由基对以EPR光谱法检测到的未配对电子旋转的特征是。对激进对重组的有效电荷分离对于有效的有机光伏系统至关重要。目前，有机光伏研究的研究集中在导致能量转化效率提高的非富勒烯受体上。在过去十年中，基于非富勒烯受体的光伏细胞在效率上一直显示出巨大的增长，速度比基于富勒烯的类似受体快得多。由于EPR和EDMR可以遵循从电荷转移状态到分开的指控的演变，因此该项目的目的是使用这些方法来更好地了解包括先进的非熟料受体在内的捐助者混合物。不同的连续波和脉冲EPR和EDMR实验将用于表征有机光伏材料中自旋中心的性质和动力学。特别是，将使用先进的脉冲EPR和EDMR技术研究自旋中心与它们的分子环境的相互作用，包括与附近磁性核和偶极相互作用以及自旋中心之间的交换相互作用的相互作用。目的是获得与太阳能电池运行相关的电荷分离，重组和运输过程的分子级别的见解，并确定有效能量转化的分子需求。数字电子产品的最新发展使形状脉冲将其整合到脉冲EPR序列中。与传统的矩形脉冲相比，形状脉冲可以增加自旋对照和新实验的设计，并具有提高灵敏度，并且在磁相互作用的表征上的准确性提高。已经证明了形状脉冲可以提高EPR对生物系统结构表征的敏感性，但迄今尚未用于帮助研究有机电子材料中的自旋中心。该项目将涉及为开发用于利用形状脉冲在这些材料中旋转表征的优势的EPR实验的开发。在EDMR中，目前仍未探索形状脉冲的使用，因此，该项目还将通过包含形状的脉冲和新型脉冲序列的设计来进一步开发脉冲EDMR方法，从而利用其提供的增加的自旋控制。该项目在物理，化学和材料科学的界面上与EPSRC对研究中的跨学科性的关注一致。从EPR和EDMR光谱中获得的见解对有机光伏中太阳能转化为电力的基本过程将对太阳能技术领域具有重要意义。开发的方法和方法还与物理科学主题中的许多其他研究领域有关，包括光电子，旋转型和量子计算。