Understanding the role of polymer structures on electronic processes in polymer optoelectronic devices

发光聚合物为低成本、大面积的设备提供了一种新技术，对电子工业产生了重大影响。如果有关效率、寿命和耐用性的问题得到解决，下一代聚合物器件将有潜力成为照明应用、光伏器件和场效应晶体管的超高效率器件。本文提出的研究重点是了解聚合物结构在决定聚合物器件性能和效率的三个重要且相关的电子过程中的作用，最终目的是制定提高这些器件性能的策略。要研究的电子过程是(i)决定单线态激子产率的过程，从而决定发光器件的电致发光量子效率；（ii）聚合物薄膜中的激子输运，这决定了光伏器件的效率；（iii）长寿命界面态对电子-空穴复合和解离的作用，这决定了发光或光伏器件的效率。这些过程受到各种长度尺度上的聚合物结构的影响，包括聚合物的化学结构、局部聚合物构象、聚合物的相对堆积和整体中尺度形态。利用各种计算技术（包括电子结构的量子化学计算，电荷和能量输运的量子主方程模拟，聚合物构象和堆积的分子动力学模拟），本建议的重点是理解化学结构，构象和堆积对这些过程效率的作用。这将为提高聚合物器件的性能提供策略。它还将提供有关如何将现有设备的效率与其理论最优值进行比较的指导。

Light emitting polymers are making a major impact in the electronics industry by providing a new technology for low-cost, large-area devices. Provided that issues regarding efficiency, lifetime and durability are resolved, the next generation of polymer devices have the potential for an even greater impact as ultra-high efficiency devices for lighting applications, photovoltaic devices, and field effect transistors.The research proposed here is focussed on understanding the role of polymer structures on three important and related electronic processes that determine the performance and efficiency of polymer devices, with the ultimate aim of developing strategies to enhance the performance of these devices. The electronic processes to be investigated are (i) processes that determine the singlet exciton yield, and hence the electroluminescence quantum efficiency of light emitting devices; (ii) exciton transport in polymer films, which determines the efficiency of photovoltaic devices; and (iii) the role of long-lived interface states on electron-hole recombination and dissociation, which determines the efficiency of either light emitting or photovoltaic devices.These processes are affected by polymer structures on a variety of length scales, including the chemical structure of the polymers, local polymer conformations, the relative packing of polymers, and the global mesoscale morphology. Using a variety of computational techniques (including quantum chemistry calculations of electronic structure, quantum master equation simulations of charge and energy transport, and molecular dynamics simulations of polymer conformation and packing) the present proposal is focussed on understanding the roles of chemical structure, conformation and packing on the efficiency of these processes. This will provide strategies for enhancing the performance of polymer devices. It will also provide guidance as to how the efficiency of present devices compares to their theoretical optimal values.