Institute for Molecular Science, Okazaki, Aichi 444-0865, Japan.
Department of Applied Chemistry and Biochemical Engineering, Graduate School of Engineering, Shizuoka University, Hamamatsu, Shizuoka 432-8561, Japan.
J Chem Phys. 2019 Sep 21;151(11):114109. doi: 10.1063/1.5113944.
Predicting the charge-transfer (CT) excited states across the donor/acceptor (D/A) interface is essential for understanding the charge photogeneration process in an organic solar cell. Here, we present a fragment-based GW implementation that can be applied to a D/A interface structure and thus enables accurate determination of the CT states. The implementation is based on the fragmentation approximation of the polarization function and the combined GW and Coulomb-hole plus screened exchange approximations for self-energies. The fragment-based GW is demonstrated by application to the pentacene/C interface structure containing more than 2000 atoms. The CT excitation energies were estimated from the quasiparticle energies and electron-hole screened Coulomb interactions; the computed energies are in reasonable agreement with experimental estimates from the external quantum efficiency measurements. We highlight the impact of the induced polarization effects on the electron-hole energetics. The proposed fragment-based GW method offers a first-principles tool to compute the quasiparticle energies and electronic excitation energies of organic materials.
预测给体/受体 (D/A) 界面处的电荷转移 (CT) 激发态对于理解有机太阳能电池中的电荷光生过程至关重要。在这里，我们提出了一种基于片段的 GW 实现方法，可应用于 D/A 界面结构，从而能够准确确定 CT 态。该实现方法基于极化函数的分段近似和用于自能的组合 GW 和库仑孔加屏蔽交换近似。通过将基于片段的 GW 应用于包含超过 2000 个原子的并五苯/C 界面结构，验证了该方法的有效性。CT 激发能是从准粒子能量和电子-空穴屏蔽库仑相互作用中估计的；计算出的能量与外量子效率测量的实验估计值吻合良好。我们强调了诱导极化效应对电子-空穴能态的影响。所提出的基于片段的 GW 方法为计算有机材料的准粒子能量和电子激发能提供了一种第一性原理工具。
