Gajdos Fruzsina, Oberhofer Harald, Dupuis Michel, Blumberger Jochen
†University College London, Department of Physics and Astronomy, London WC1E 6BT, United Kingdom.
‡Technical University Munich, Theoretical Chemistry, Lichtenbergstr. 4, D-85747 Garching, Germany.
J Phys Chem Lett. 2013 Mar 21;4(6):1012-7. doi: 10.1021/jz400227c. Epub 2013 Mar 13.
Phenyl-C61-butyric acid methyl ester (PCBM) is one of the most popular semiconductors in organic photovoltaic cells, but the electron-transport mechanism in the microcrystalline domains of this material as well as its preferred packing structure remain unclear. Here we use density functional theory to calculate electronic-coupling matrix elements, reorganization energies, and activation energies for available experimental and model crystal structures. We find that the picture of an excess electron hopping from one fullerene to another does not apply for any of the crystalline phases, rendering traditional rate equations inappropriate. We also find that the cohesive energy increases in the order body-centered-cubic < hexagonal < simple cubic < monoclinic < triclinic, independently of the type of dispersion correction used. Our results indicate that the coupled electron-ion dynamics needs to be solved explicitly to obtain a realistic description of charge transfer in this material.
苯基 - C61 - 丁酸甲酯（PCBM）是有机光伏电池中最常用的半导体之一，但这种材料微晶域中的电子传输机制及其优选的堆积结构仍不清楚。在这里，我们使用密度泛函理论来计算现有实验和模型晶体结构的电子耦合矩阵元、重组能和活化能。我们发现，一个多余电子从一个富勒烯跳跃到另一个富勒烯的图景不适用于任何晶相，这使得传统速率方程不适用。我们还发现，内聚能按体心立方＜六方＜简单立方＜单斜＜三斜的顺序增加，与所使用的色散校正类型无关。我们的结果表明，需要明确求解耦合的电子 - 离子动力学，以获得该材料中电荷转移的现实描述。
