Perylene bisimides (PBIs) have received great attention in their applicability to optoelectronics. Especially, symmetry-breaking charge separation (SB-CS) in PBIs has been investigated to mimic the efficient light capturing and charge generation in natural light-harvesting systems. However, unlike ultrafast CS dynamics in donor–acceptor heterojunction materials, ultrafast SB-CS in a stacked homodimer has still been challenging due to excimer formation in the absence of rigidifying surroundings such as a special pair in the natural systems. Herein, we present the detailed mechanism of ultrafast photoinduced SB-CS occurring in a 1,7-bis(N-pyrrolidinyl) PBI dimer within a cyclophane. Through narrow-band and broad-band transient absorption spectroscopy, we demonstrate that ultrafast SB-CS in the dimer is enabled by the combination of (1) vibrationally coherent charge-transfer resonance-enhanced excimer formation and (2) breakdown of adiabaticity (formation of SB-CS diabats) in the excimer state via structural and solvent fluctuation. Quantum chemical calculations also underpin that the participation of strong electron-donating substituents in overall vibrational modes plays a crucial role in triggering the ultrafast SB-CS. Therefore, our work provides an alternative route to facilitate ultrafast SB-CS in PBIs and thereby establishes a novel strategy for the design of optoelectronic materials.

中文翻译：

---

通过振动耦合和绝热性破坏实现苝双酰亚胺二聚体中的超快对称破坏电荷分离

苝双酰亚胺（PBI）因其在光电子学中的适用性而备受关注。特别是，已经研究了 PBI 中的对称破缺电荷分离 (SB-CS)，以模拟自然光捕获系统中的有效光捕获和电荷产生。然而，与供体-受体异质结材料中的超快 CS 动力学不同，堆叠同源二聚体中的超快 SB-CS 仍然具有挑战性，因为在没有刚性环境（例如自然系统中的特殊对）的情况下形成了准分子。在此，我们提出了在 1,7-bis( N-吡咯烷基) PBI 二聚体在环烷中。通过窄带和宽带瞬态吸收光谱，我们证明二聚体中的超快 SB-CS 是由（1）振动相干电荷转移共振增强准分子形成和（2）绝热性破坏（形成SB-CS diabats）通过结构和溶剂波动处于准分子状态。量子化学计算也证实了强给电子取代基在整体振动模式中的参与在触发超快 SB-CS 中起着至关重要的作用。因此，我们的工作提供了一种替代途径来促进 PBI 中的超快 SB-CS，从而为光电材料的设计建立了一种新的策略。