Evolution of the Electronic Properties of Conjugated Materials from Isolated Molecules to Aggregates

在这个由化学系化学结构、动力学和机制项目资助的项目中，Linda Peteanu教授和她的学生将致力于更好地理解将聚合物转化为工作装置所需的化学和物理处理步骤如何影响其电荷传输和发光能力。这些知识是为下一代光伏器件和低功耗照明成功设计最高效、轻便、灵活、基于聚合物的材料所必需的。Peteanu团队专注于这些关键性能如何受到聚合或聚合物链之间的相互作用的影响，这些作用在形成固态薄膜的过程中不可避免地会发生。本研究通过对电致发光聚合物MEH-PPV、CN-PPV和聚芴的短链模型低聚物在溶剂中毒作用下形成的聚合体和单分子水平的光谱学研究来解决这些问题。这些低聚物聚集体是更复杂聚合物的光谱学和动力学的优秀模型系统。此外，幸运的是，它们没有结构缺陷，这使得解释聚合物数据变得更加困难。利用单聚集体的光子相关和体样品的超快光谱测量了其发光特性和能量传递动力学。超快光谱和斯塔克光谱也被用于探测这些材料中的电荷分离和输运。与David Yaron （CMU）合作进行电子结构计算，然后可以获得这些系统中结构，光谱和动力学的统一图像。这些努力不仅有助于节能设备的发展，而且有助于培训能够利用其商业潜力的劳动力。

In this project, funded by the Chemical Structure, Dynamics and Mechanisms Program of the Chemistry Division, Professor Linda Peteanu and her students will work towards a better understanding of how the chemical and physical processing steps required to turn a polymer into a working device affect its charge transport and light emitting capabilities. This knowledge is required for the successful design of the most efficient lightweight, flexible, polymer-based materials for next-generation photovoltaic devices and low power consumption lighting. The Peteanu group focuses on how these critical properties are impacted by aggregation or the interactions between polymer chains that inevitably occur during processing to form solid state films. This proposal addresses these issues by optical spectroscopy on the bulk and single molecule level of aggregates formed from short-chain model oligomers of the electroluminescent polymers MEH-PPV, CN-PPV and polyfluorene by solvent poisoning. These oligomer aggregates are excellent model systems for the spectroscopy and dynamics of the more complex polymers. Moreover, they fortunately lack the structural defects that make interpreting the polymer data more difficult. The light emitting properties and energy transfer dynamics are measured using photon correlation in single aggregates and ultrafast spectroscopy in bulk samples. Ultrafast spectroscopy and Stark spectroscopy are used to probe charge separation and transport in these materials as well. Electronic structure calculations in collaboration with David Yaron (CMU) then enable obtaining a unified picture of the structure, spectroscopy, and dynamics in these systems. These efforts contribute not only to the development of energy saving devices but to training of a work force that can capitalize on their commercial potential.