Comparison of the electronic structure of different perylene‐based dye‐aggregates
Comparison of the electronic structure of different perylene‐based dye‐aggregates
复制标题
DOI：
10.1002/jcc.22986
复制
发表时间：
2012-07
影响因子：
3
通讯作者：
Volker Settels;Wenlan Liu;J. Pflaum;R. Fink;B. Engels
中科院分区：
文献类型：
--
作者：
Volker Settels;Wenlan Liu;J. Pflaum;R. Fink;B. Engels
功能化多环芳香族分子的聚集体，如苝衍生物，在吸收和发射光谱或激子扩散长度等重要光电性质上存在差异。虽然这些差异是众所周知的，但尚不完全清楚它们是由聚集物内分子几何方向的变化、染料聚集物电子结构的变化还是两者的相互作用引起的。由于这些知识对开发具有优化功能的材料很感兴趣，我们通过比较具有代表性的苝基发色团的二聚体系统的电子结构来研究这个问题。该研究包括苝二聚体，3,4,9,10‐苝四羧酸二亚胺（PBI）， 3,4,9,10‐苝四羧酸二酐（PTCDA）和二氨基苝（DIP）。研究了决定材料光电性能的势能曲线及其电子态的特征。计算使用自旋分量尺度近似耦合簇二阶方法（SCS - CC2），该方法可以很好地描述主要为中性激发（NE）和电荷转移（CT）特征的电子状态。我们的研究结果表明，激发态的特征随着分子间取向的变化而发生显著变化，并且经常表现为NE和CT特征的显著混合。然而，所研究的苝衍生物的PECs和电子结构几乎与苝核心的取代模式无关，这表明所观察到的光电性能差异主要是由染料聚集体的几何结构引起的。这也暗示了这样一个事实，即如果选择适当的聚集几何形状，则可以从取代较少的模型化合物中计算光学性质。©2012 Wiley期刊公司
Aggregates of functionalized polycyclic aromatic molecules like perylene derivatives differ in important optoelectronic properties such as absorption and emission spectra or exciton diffusion lengths. Although those differences are well known, it is not fully understood if they are caused by variations in the geometrical orientation of the molecules within the aggregates, variations in the electronic structures of the dye aggregates or interplay of both. As this knowledge is of interest for the development of materials with optimized functionalities, we investigate this question by comparing the electronic structures of dimer systems of representative perylene‐based chromophores. The study comprises dimers of perylene, 3,4,9,10‐perylene tetracarboxylic acid bisimide (PBI), 3,4,9,10‐perylene tetracarboxylic acid dianhydride (PTCDA), and diindeno perylene (DIP). Potential energy curves (PECs) and characters of those electronic states are investigated which determine the optoelectronic properties. The computations use the spin‐component‐scaled approximate coupled‐cluster second‐order method (SCS‐CC2), which describes electronic states of predominately neutral excited (NE) and charge transfer (CT) character equally well. Our results show that the characters of the excited states change significantly with the intermolecular orientation and often represent significant mixtures of NE and CT characters. However, PECs and electronic structures of the investigated perylene derivatives are almost independent of the substitution patterns of the perylene core indicating that the observed differences in the optoelectronic properties mainly result from the geometrical structure of the dye aggregate. It also hints at the fact that optical properties can be computed from less‐substituted model compounds if a proper aggregate geometry is chosen. © 2012 Wiley Periodicals, Inc.