Frost Jarvist M, Kirkpatrick James, Kirchartz Thomas, Nelson Jenny
Department of Physics and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, UK.
Faraday Discuss. 2014;174:255-66. doi: 10.1039/c4fd00153b. Epub 2014 Sep 24.
We investigate the influence of intra-chain and inter-chain interactions on the sub-gap density of states in a conjugated polymer using a combination of atomistic molecular dynamics simulation of polymer film structure and tight-binding calculation of electronic energy levels. For disordered assemblies of poly-3-hexylthiophene we find that the tail of the density of hole states is approximately exponential with a characteristic energy of 37 meV, which is similar to experimental values. This tail of states arises mainly from variations in the electronic coupling between neighbouring monomers, and is only slightly influenced by interchain coupling. Thus, knowledge of the disorder in torsion between neighbouring monomers is sufficient to estimate the density of states for the polymer. However, the intrachain torsional disorder is determined largely by the packing of the chains rather than the torsional potential alone. We propose the combination of methods as a tool to design higher mobility conjugated polymers.
我们使用聚合物薄膜结构的原子分子动力学模拟和电子能级的紧束缚计算相结合的方法，研究了共轭聚合物中链内和链间相互作用对亚能隙态密度的影响。对于聚3-己基噻吩的无序组装体，我们发现空穴态密度的尾部近似呈指数形式，特征能量为37毫电子伏特，这与实验值相似。这种态的尾部主要源于相邻单体之间电子耦合的变化，并且仅受链间耦合的轻微影响。因此，了解相邻单体之间扭转的无序性就足以估计聚合物的态密度。然而，链内扭转无序在很大程度上由链的堆积决定，而不仅仅由扭转势决定。我们提出将这些方法结合起来作为设计更高迁移率共轭聚合物的工具。
