Transient localization of charge carriers in organic semiconductors

在这个合作研究项目中，我们希望阐明有机半导体中的电荷传输机制及其固有的局限性。重点将是最近的建议，动态分子无序管理的光学性质和电荷载流子的运输，非常具体的预测直流迁移率和低频光吸收的电荷载流子注入或激发跨越能隙。分子无序的动力学性质阻止了载流子长时间的定位;即无序势的波动破坏了负责安德森局域化的量子干涉。我们的三个高知名度团队完全涵盖了从材料纯化和晶体生长，样品表征，器件制造，光谱学，电荷载流子动力学研究，建模和理论描述。计划中的实验将在显示优先空穴的高质量分子单晶（红荧烯、并五苯等）上进行。或电子传导（二氯萘二酰亚胺等）并且可以通过场效应或光激发来掺杂电荷载流子。我们计划测量的光学电导率，场效应晶体管的迁移率以及噪声谱密度的晶体方向，温度，频率，载流子密度和掺杂引起的，静态的障碍的函数。这些实验将提供定量的证据，发生在分子半导体的电子传输的瞬态本地化，从而使我们能够改善和推进理论概念和建模的动态电荷载流子运动在这类材料。

In this collaborative research project we want to elucidate the charge-transport mechanisms in organic semiconductors and their intrinsic limitations. The focus will be on the recent suggestion that dynamical molecular disorder governs the optical properties and charge-carrier transport, with very specific predictions on the dc mobility and low-frequency optical absorption of the charge carriers injected or excited across the energy gap. The dynamical nature of molecular disorder prevents localization of the carriers at long times; i.e. fluctuations of the disorder potential destroy the quantum interferences responsible for Anderson localization.Our team of three high-profile groups completely covers the full range from material purification and crystal growth, sample characterization, device fabrication, optical spectroscopy, investigations of the charge-carrier dynamics, modelling and theoretical description. The projected experiments will be performed on high-quality molecular single crystals showing preferred hole (rubrene, pentacene, etc.) or electron conduction (dichloro-naphthalene-diimde, etc.) and which can be charge carrier-doped by either field-effect or photo-excitations. We plan to measure the optical conductivity, the FET mobility as well as the noise spectral density as a function of crystallographic direction, temperature, frequency, carrier density and doping-induced, static disorder. The experiments will provide quantitative evidence for the occurrence of transient localization in the electronic transport of molecular semiconductors and thus will allow us to improve and advance theoretical concepts and modelling of the dynamical charge carrier motion in this material class.