GW/BSE级别下的非绝热动力学模拟揭示桥连化学键对调控酞菁锌-富勒烯给体-受体复合物激发态弛豫过程的重要作用

本文采用基于多体格林函数方法和Bethe-Salpeter方程(GW/BSE)的电子结构计算方法和非绝热动力学模拟研究了两种不同桥连化学键构型(5-6构型和6-6构型)的酞菁锌-富勒烯(ZnPc-C₆₀)给受体复合物的激发态性质及其弛豫过程. 对于6-6构型，ZnPc-C₆₀的最低激发态S₁态为光谱明态，即ZnPc的局域激发(LE)态，因此，6-6构型的ZnPc-C₆₀在光激发之后几乎不会发生电荷分离过程. 相比之下，5-6构型的ZnPc-C₆₀的S₁态是C₆₀的LE态，为光谱暗态，而作为光谱明态的ZnPc的LE态的能量更高. 而且，在ZnPc和C₆₀的LE态之间还存在若干电荷转移(CT)态. 因此，电荷转移会在从高能的ZnPc的LE态到低能的C₆₀的LE态的弛豫过程中发生. GW/BSE级别的非绝热动力学模拟结果进一步验证了电子结构计算的结论，并给出了相关过程的时间尺度：从ZnPc到C₆₀的超快激发态能量转移过程在前200 fs完成；随后发生的是由C₆₀到ZnPc的超快空穴转移过程. 本工作表明不同的桥连化学键模式(即5-6和6-6构型)可用于调节ZnPc-C₆₀给体-受体复合物的激发态性质及其光电性质. 与此同时，本工作证明了GW/BSE级别的非绝热动力学方法是探索非周期性给体-受体复合物、有机金属配合物、量子点、纳米团簇等复杂体系的光诱导动力学的可靠工具.

GW/BSE Nonadiabatic Dynamics Simulations on Excited-State Relaxation Processes of Zinc Phthalocyanine-Fullerene Dyads: Roles of Bridging Chemical Bonds

In this work, we employ electronic structure calculations and nonadiabatic dynamics simulations based on many-body Green function and Bethe-Salpeter equation (GW/BSE) methods to study excited-state properties of a zinc phthalocyanine-fullerene (ZnPc-C₆₀) dyad with 6-6 and 5-6 configurations. In the former, the initially populated locally excited (LE) state of ZnPc is the lowest S₁ state and thus, its subsequent charge separation is relatively slow. In contrast, in the latter, the S₁ state is the LE state of C₆₀ while the LE state of ZnPc is much higher in energy. There also exist several charge-transfer (CT) states between the LE states of ZnPc and C₆₀. Thus, one can see apparent charge separation dynamics during excited-state relaxation dynamics from the LE state of ZnPc to that of C₆₀. These points are verified in dynamics simulations. In the first 200 fs, there is a rapid excitation energy transfer from ZnPc to C₆₀, followed by an ultrafast charge separation to form a CT intermediate state. This process is mainly driven by hole transfer from C₆₀ to ZnPc. The present work demonstrates that different bonding patterns (i.e. 5-6 and 6-6) of the C?N linker can be used to tune excited-state properties and thereto optoelectronic properties of covalently bonded ZnPc-C₆₀ dyads. Methodologically, it is proven that combined GW/BSE nonadiabatic dynamics method is a practical and reliable tool for exploring photoinduced dynamics of nonperiodic dyads, organometallic molecules, quantum dots, nanoclusters, etc.