Theory and simulations of electronic processes in organic semiconductors

本项目涉及有机半导体系统中电荷和能量转移过程的理论和数值模拟。项目的两个主要部分集中在特定核运动的作用和一种“模式投影”技术，该技术允许将高维量子动力学计算减少到只涉及几个特定的“集体”模式。我们的目标是了解这种集体模式如何在光收集系统和电荷转移系统中发挥作用。实际上，这些模式为“反应坐标”提供了严格的、分子水平的描述。第三个组成部分涉及预测有机分子晶体和自组装有机半导体聚合物体系中激子极化电子态的性质。特别令人感兴趣的是，在这些系统中存在极化玻色凝聚态的可能性。这种凝聚体已经在砷化镓微腔中观察到，但到目前为止还没有在有机微腔中观察到。“模式投影”技术可以应用于电子-声子系统以外的广泛情况，从而为电子结构理论或电子输运理论中的有效算法提供了一条途径。该项目中涉及的系统对分子电子器件很有意义。关于极化激子BEC的工作，虽然肯定有风险，但有相当大的希望产生广泛的影响，因为到目前为止，这种状态还没有在有机半导微腔中观察到。这些系统中的理论和模拟为这一方向的实验工作提供了亟需的指导。当然，最广泛的影响是对参与该项目的博士生和博士后研究人员的培训。该奖项由化学部的理论模型和计算方法项目资助。

This project concerns theoretical and numerical simulations of charge and energy transfer processes in organic semiconducting systems. Two major project components are focused upon the role of specific nuclear motions and a "mode projection" technique that allows to reduce a high-dimensional quantum dynamics calculation to one involving only a few specific "collective" modes. The goal is to understand how such collective modes come into play in light-harvesting systems and charge-transfer systems. In effect, these modes provide a rigorous and molecular level description of the "reaction coordinate." A third component concerns predicting the properties of exciton polariton states in organic molecular crystals and self-assembled organic semiconducting polymer systems. Of particular interest is the possibility of polariton Bose condensate states in these systems. Such condensates have been observed in GaAs microcavities but, thus far, not in organic microcavities.The "mode projection" technique can be applied in a wide range of cases beyond electron-phonon systems and, thus, offer an avenue for efficient algorithms in electronic structure theory or electronic transport theory. The systems addressed in the project are of interest for molecular electronic devices. The work on polariton BEC, while certainly risky, holds considerable promise for broad impact since such states have not been observed to date in organic semicondicting microcavities. The theory and simulations in these systems provide much needed guidance for experimental efforts in this direction. Certainly, the broadest impact is in the training of PhD students and postdoctoral researchers involved in this project. This award is funded by the Theory Models and Computational Methods program of the Chemistry Division.