Conical intersections (CoIns) of multidimensional potential energy surfaces are ubiquitous in nature and control pathways and yields of many photo-initiated intramolecular processes. Such topologies can be potentially involved in the energy transport in aggregated molecules or polymers but are yet to be uncovered. Here, using ultrafast two-dimensional electronic spectroscopy (2DES), we reveal the existence of intermolecular CoIns in molecular aggregates relevant for photovoltaics. Ultrafast, sub-10-fs 2DES tracks the coherent motion of a vibrational wave packet on an optically bright state and its abrupt transition into a dark state via a CoIn after only 40 fs. Non-adiabatic dynamics simulations identify an intermolecular CoIn as the source of these unusual dynamics. Our results indicate that intermolecular CoIns may effectively steer energy pathways in functional nanostructures for optoelectronics.

多维势能面的锥形交叉点 (CoIns) 在自然界中普遍存在，并控制许多光引发分子内过程的途径和产量。这种拓扑可能潜在地参与聚集分子或聚合物的能量传输，但尚未被发现。在这里，我们使用超快二维电子光谱 (2DES)，揭示了与光伏相关的分子聚集体中存在分子间 CoIns。超快、亚 10-fs 2DES 跟踪振动波包在光学明亮状态下的相干运动，并在仅 40 fs 后通过 CoIn 突然转变为暗状态。非绝热动力学模拟将分子间 CoIn 识别为这些异常动力学的来源。