Charge Photogeneration and Recombination in Organic Semiconductors

本项目的目标是获得对有机半导体中电荷光产生和重组的基本理解。方法是使用新的实验方法来回答基本问题，并提供机械洞察力。时间延迟场收集技术将用于量化共轭聚合物中的电荷产生，而不需要光电导率或光谱测量的模糊性。将测试波长、场和温度对电荷产率的依赖理论。包括瞬态泵和转储实验，研究电荷产生的机理。为了研究复合，将使用时间门控和热激发发光来询问失去自旋相关的光生电荷的复合。这种方法使结果与电致发光器件相关，但没有接触处淬火和低温运输冻结的困难。该项目的一个重要影响是通过研究和教育的整合在教育和人力资源开发方面。该项目涉及研究生和本科生，包括来自少数民族服务机构CCNY的暑期访问学生，以及正在做高级论文的本科生参与我们的研究。PI还积极开展外联活动，邀请高中生进行研究。各级参与者将以口头和书面形式介绍他们的工作，作为他们经验的一部分，并传播在研究中获得的知识。PI和学生们还与参与小组研究的几位退休和活跃的工业同事进行互动。他们的投入有助于与基础研究可以产生重要影响的技术相关问题建立联系。其中一个重点是提高对共轭聚合物中电荷光产生的理解，因为它与基于有机材料的太阳能电池和光伏发电的发展有关。一个类似的目标是确定由不相关自旋的电荷重组所产生的状态，因为它与聚合物led材料的选择有关

The goal of this project is to gain fundamental understanding of charge photogeneration and recombination in organic semiconductors. The approach is to use fresh experimental approaches designed to answer basic questions and to provide mechanistic insight. A time delayed field collection technique will be used to quantify charge generation in conjugated polymers without the ambiguities of photoconductivity or spectroscopic measurements. Theories for the wavelength, field and temperature dependence of charge generation yield will be tested. Transient pump and dump experiments that address the mechanism of charge generation are included. To study recombination, time-gated and thermally stimulated luminescence will be used to interrogate recombination of photogenerated charges that have lost spin correlation. This approach makes the results relevant to electroluminescent devices but is free from the difficulties of quenching at contacts and freezeout of transport at low temperature. %%% An important impact of the project is in education and human resource development through the integration of research and education. The project involves graduate and undergraduate students, including visiting summer students from a minority serving institution, CCNY, with undergraduates doing senior theses taking part in our research. The PI is also active in outreach activities hosting high school students to do research. Participants at all levels will present their work orally and in writing as a part of their experience and to disseminate knowledge obtained in the research. The PI and students also interact with several retired and active industrial colleagues who participate in group research. Their input assists connections to technologically relevant issues where basic research can have important impact. One such thrust is to improve understanding of charge photogeneration in conjugated polymers as it pertains to development of solar cells and photovoltaics based on organic materials. A similar goal is to identify the states resulting from recombination of charges with uncorrelated spins as it pertains to selection of materials for polymer LEDs.***