Collaborative Research: Quasiparticle Transport in Organic Materials: Vibrational Dressing, Static Disorder, Nanoscale Confinement, and Quantum Effects

这是新墨西哥大学和密苏里大学罗拉分校的合作研究项目。所进行的研究是理论的，采用分析和计算机方法，一方面处理有机材料中准粒子输运的基本问题，另一方面应用于技术上重要的系统和设备。它解决的基本问题包括动态无序，静态无序，激烈的应用领域，载流子-载流子相互作用，以及由所研究系统的特征尺寸变化引起的量子效应。准粒子（如电子）与分子的振动和其他振荡运动的强相互作用打破了平移不变性，构成了动态失序。一些有待解决的问题是非常新的，而另一些则是长期存在但尚未解决的问题：有机固体中电荷和能量的基本载体的性质是什么？在多大程度上，它们在空间中是局部的或扩展的，是自由的或与它们周围的扭曲（极性）相关联的，它们的运动是连贯的还是不连贯的？从中尺度到纳米尺度的系统尺寸变化可能会对动力学产生哪些新的影响？要进行的理论研究将寻求确定在何种条件下输运是正常的或（以及在何种定量程度上）色散意义上的异常，以便应用普通平衡统计力学不会误导实验的定量评估。研究还将解决复合粒子形成的可能性，以及对实验的影响：电子-光子（例如，极化子），激子-声子（例如，准分子），声子-声子（例如，振动子）和激子-光子（例如，极化子）在组成元素的特征运动时间不同的限制下。在有机材料中，由于随机分子包装、化学杂质、电荷偶极相互作用以及取向和空间的不均匀性，产生了空间和能量上的静态无序。这种机制可以而且经常导致以大量空间相关性为特征的静态失序。研究将集中在这些关联的来源和可能的控制，以及它们对准粒子输运的影响。研究将在相关和不相关的无序源之间发生的相互作用和竞争，以及各种效应，如极化系统中的速率反转，这些效应可能由高场、电荷的极化性质和无序的组合引起。基于对准粒子量子输运基本方面的研究，该研究将集中于许多实际设备问题和现象，包括电荷偶极相互作用的筛选，注入过程中电荷的相互作用，有机发光二极管和场效应晶体管的界面效应，重组和光生。它还将解决特殊的器件特征，如几何约束、降维、减少相空间，特别是纳米尺度（更合适的是中微纳米尺度）的过渡。这是新墨西哥大学和密苏里大学罗拉分校之间的一个合作研究项目。所进行的研究是理论的，采用分析和计算机方法，一方面处理有机材料中准粒子输运的基本问题，另一方面应用于技术上重要的系统和设备。＊＊＊

0097204KenkreThis is a Collaborative Research Project between the University of New Mexico and the University of Missouri at Rolla. The research performed is theoretical, employ analytic and computer methods, and deals with fundamental issues of quasiparticle transport in organic materials on the one hand, and applications to technologically important systems and devices on the other hand. Among the fundamental issues it addresses are dynamic disorder, static disorder, intense applied fields, carrier-carrier interactions, and quantum effects arising from variation in the characteristic size of the systems under study.Breaking the translational invariance by strong interactions of quasiparticles, such as electrons, with vibrations and other oscillatory motions of molecules, constitutes dynamic disorder. Some of the issues to be addressed are very new, while others are longstanding but unresolved: What is the nature of the fundamental carriers of charge and enegy in organic solids? To what extent are they localized or extended in space, free or associated with distortions around them (polaronic), coherent or incoherent in their motion? What new effects on dynamics may be expected as a result of system size variation from the mesoscale to the nanoscale? Theoretical investigations to be performed will seek to determine conditions under which transport is normal or (and to what quantitative extent) anomalous in the sense of dispersive, so that application of ordinary equilibrium statistical mechanics may not mislead quantitative assessment of experiment. Investigations will also address the possibility of formation, as well as the effects on experiments, of composite particles: electron-photon (e.g., polaron), exciton-phonon (e.g., excimer), phonon-phonon (e.g., vibron), and exciton-photon (e.g., polariton) in limits in which the characteristic motion times of the constituent elements are disparate.Static disorder, both spatial and energetic, arises in organic materials from random molecular packings, chemical impurities, charge-dipole interactions, and orientational and spatial inhomogeneities. Such mechanisms can, and often do, lead to static disorder chacterized by substantial spatial correlations. Research will focus on the sources and possible control of such correlations and their effects on quasiparticle transport. Studies will be performed of the interplay and competition that occurs between correlated and uncorrelated sources of disorder, and a variety of effects, such as rate inversion in polaronic systems, that can arise from a combination of high fields, the polaronic nature of charge, and disorder.On the basis of insights gained through this work on fundamental aspects of quantum transport of quasiparticles, the research will focus on a number of practical device issues and phenomena including the screening of charge-dipole interactions, the mutual interaction of charges during injection, interfacial effects in organic light-emitting diodes and field effect transistors, recombination, and photogeneration. It will also address special device features such as geometrical constraints, reduced dimensionality, reduced phase space, and particularly the nanoscale (more appropriately the meso-micro-nano-scale) transition.%%% This is a Collaborative Research Project between the University of New Mexico and the University of Missouri at Rolla. The research performed is theoretical, employ analytic and computer methods, and deals with fundamental issues of quasiparticle transport in organic materials on the one hand, and applications to technologically important systems and devices on the other hand. ***