Wilcox Daniel E, Lee Myeong H, Sykes Matthew E, Niedringhaus Andrew, Geva Eitan, Dunietz Barry D, Shtein Max, Ogilvie Jennifer P
†Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109, United States.
∥Department of Chemistry, Kent State University, 214 Williams Hall, Kent, Ohio 44242, United States.
J Phys Chem Lett. 2015 Feb 5;6(3):569-75. doi: 10.1021/jz502278k. Epub 2015 Jan 27.
Photoinduced charge-transfer (CT) processes play a key role in many systems, particularly those relevant to organic photovoltaics and photosynthesis. Advancing the understanding of CT processes calls for comparing their rates measured via state-of-the-art time-resolved interface-specific spectroscopic techniques with theoretical predictions based on first-principles molecular models. We measure charge-transfer rates across a boron subphthalocyanine chloride (SubPc)/C60 heterojunction, commonly used in organic photovoltaics, via heterodyne-detected time-resolved second-harmonic generation. We compare these results to theoretical predictions based on a Fermi's golden rule approach, with input parameters obtained using first-principles calculations for two different equilibrium geometries of a molecular donor-acceptor in a dielectric continuum model. The calculated rates (∼2 ps(-1)) overestimate the measured rates (∼0.1 ps(-1)), which is consistent with the expectation that the calculated rates represent an upper bound over the experimental ones. The comparison provides valuable understanding of how the structure of the electron donor-acceptor interface affects the CT kinetics in organic photovoltaic systems.
光诱导电荷转移（CT）过程在许多系统中起着关键作用，特别是那些与有机光伏和光合作用相关的系统。要深入理解CT过程，需要将通过先进的时间分辨界面特异性光谱技术测量的速率与基于第一性原理分子模型的理论预测进行比较。我们通过外差检测时间分辨二次谐波产生来测量常用在有机光伏中的硼亚酞菁氯（SubPc）/C60异质结上的电荷转移速率。我们将这些结果与基于费米黄金规则方法的理论预测进行比较，其输入参数是使用介电连续体模型中分子供体 - 受体的两种不同平衡几何结构的第一性原理计算获得的。计算出的速率（约2 ps⁻¹）高估了测量速率（约0.1 ps⁻¹），这与计算出的速率代表实验速率上限的预期一致。这种比较为电子供体 - 受体界面的结构如何影响有机光伏系统中的CT动力学提供了有价值的理解。
