Distinct photophysics of the spin-entangled triplet-triplet versus free triplets in organic semiconductors

有机半导体中自旋纠缠三重态与自由三重态的独特光物理学

基本信息

批准号：
1764152
负责人：
Sumitendra Mazumdar
金额：
$ 45万
依托单位：
University of Arizona
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2023-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1764152&HistoricalAwards=false
关键词：
Distinct photophysics spin entangled triplet

项目摘要

Solar cells absorb sunlight and generate electricity. Solar cells constructed out of organic molecules or polymers are of interest because they are cheap, easily processible, lighweight and flexible. The electric power generated by today's organic solar cells is limited because of thermodynamic constraints. There is currently intense scientific effort to overcome these constraints and to construct solar cells that yield higher power. One possible approach is to use singlet fission, a photophysical process within which the electrical current generated by light absorption is in principle doubled. In this project funded by the Chemical Structure Dynamics and Mechanism (CSDM-A) program of the Chemistry Division, Professor Sumitendra Mazumdar of the University of Arizona is performing quantum mechanical calculations to understand the detailed mechanism of singlet fission. Understanding of the process is needed to find new molecular materials that yield larger amounts of charge upon light absorption, which in turn may lead to organic solar cells with significantly higher efficiencies. The broader impacts of this work include cutting-edge interdisciplinary training of undergraduate and graduate students, and a postdoctoral fellow in computational chemistry and physics. Outreach efforts are fostering interest in chemistry and physics among members of underserved groups.Currently it is difficult to ascertain whether singlet fission in targeted materials is complete. The only way to distinguish between the initial optical spin-singlet and the free triplets that are end products, as well as the active intermediate triplet-triplet biexciton is from transient absorption spectroscopy, and transient absorptions in the visible from all three species are overlapping. Experiments in the near and mid infrared need to be performed to distinguish between the different excited species. The project focuses on computations of excited state absorptions from the optical spin-singlet exciton, the lowest spin-triplet exciton and the triplet-triplet biexciton, using high level configuration interaction approach and an exciton basis within a many-electron model Hamiltonian that yield physical, pictorial interpretations of many-body eigenstates and of excited state absorptions. The goal of the project is to develop structure-property correlations with predictive capability of three families of organic semiconductors that are candidates for intramolecular singlet fission. The three families are, (i) covalently linked dimers of acenes and related molecules, (ii) conjugated polymers, and (iii) low bandgap donor-acceptor copolymers. Computations are yielding diagnostic tools for experimentally distinguishing between transient absorptions from the triplet-triplet and free triplets, and determination of whether or not concerted two-electron transfers from the triplet-triplet occur in a bulk heterostructure environment, as has been proposed recently. This research project has implications for solar energy and other technologies that could be based on organic materials. The students and post-doctoral researchers involved in this project are gaining experience in state-of-the art computational methods, including many-body quantum chemistry and physics treatments.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

太阳能电池吸收阳光并发电。由有机分子或聚合物构建的太阳能电池受到人们的关注，因为它们便宜、易于加工、重量轻且灵活。由于热力学限制，当今的有机太阳能电池产生的电力受到限制。目前，科学界正在大力努力克服这些限制并建造产生更高功率的太阳能电池。一种可能的方法是使用单线态裂变，这是一种光物理过程，其中光吸收产生的电流原则上加倍。在这个由化学部化学结构动力学与机理（CSDM-A）项目资助的项目中，亚利桑那大学的Sumitendra Mazumdar教授正在进行量子力学计算，以了解单线态裂变的详细机制。需要了解这一过程才能找到新的分子材料，这些材料在吸收光时产生大量电荷，从而可能导致有机太阳能电池效率显着提高。这项工作的更广泛影响包括对本科生和研究生以及计算化学和物理学博士后的尖端跨学科培训。外展工作正在培养那些服务不足的群体成员对化学和物理的兴趣。目前很难确定目标材料中的单线态裂变是否完全。区分初始光学自旋单线态和最终产物的自由三线态以及活性中间体三线态-三线态双激子的唯一方法是通过瞬态吸收光谱，并且所有三个物种的可见光瞬态吸收是重叠的。需要进行近红外和中红外实验来区分不同的激发态物质。该项目重点计算光学自旋单重态激子、最低自旋三重态激子和三重态-三重态双激子的激发态吸收，使用高水平构型相互作用方法和多电子模型哈密顿量内的激子基础，产生物理量，多体本征态和激发态吸收的图形解释。该项目的目标是开发三个有机半导体家族的结构-性质相关性和预测能力，这三个有机半导体家族是分子内单线态裂变的候选者。这三个家族是：（i）并苯和相关分子的共价连接二聚体，（ii）共轭聚合物，以及（iii）低带隙供体-受体共聚物。正如最近提出的那样，计算正在产生诊断工具，用于通过实验区分来自三重态-三重态和自由三重态的瞬态吸收，并确定来自三重态-三重态的协同两电子转移是否发生在本体异质结构环境中。该研究项目对太阳能和其他基于有机材料的技术具有影响。参与该项目的学生和博士后研究人员正在获得最先进的计算方法的经验，包括多体量子化学和物理治疗。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准。

项目成果

期刊论文数量（11）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Wave Function Based Analysis of Dynamics versus Yield of Free Triplets in Intramolecular Singlet Fission

DOI：
10.1021/acs.jpca.0c07938
发表时间：
2020-12-10
期刊：
JOURNAL OF PHYSICAL CHEMISTRY A
影响因子：
2.9
作者：
Chesler, Rafi;Khan, Souratosh;Mazumdar, Sumit
通讯作者：
Mazumdar, Sumit

Quantum interference effects elucidate triplet-pair formation dynamics in intramolecular singlet-fission molecules

量子干涉效应阐明分子内单线裂变分子中三重线对形成动力学

DOI：
10.1038/s41557-022-01107-8
发表时间：
2023
期刊：
Nature Chemistry
影响因子：
21.8
作者：
Parenti, Kaia R.;Chesler, Rafi;He, Guiying;Bhattacharyya, Pritam;Xiao, Beibei;Huang, Huaxi;Malinowski, Daniel;Zhang, Jocelyn;Yin, Xiaodong;Shukla, Alok
通讯作者：
Shukla, Alok

Doping asymmetry in the three-band Hamiltonian for cuprate ladders: Failure of the standard model of superconductivity in cuprates