Since a couple of years ago, Y6 has emerged as one of the main non-fullerene acceptors for organic solar cells, as its use leads to superior power conversion efficiencies. It is thus of major interest to investigate the multiscale phenomena that are responsible for Y6's efficacy. Here, we modeled neat films of Y6 and earlier non-fullerene acceptors, IT-4F and ITIC, using a combination of density functional theory calculations and molecular dynamics simulations, to investigate the various factors that control their charge and exciton transport rates. We find that the molecular packing in Y6 is drastically different from that in IT-4F and ITIC. At the nanoscale, the local morphology of Y6 consists of a large number of directional face-on stackings and well-connected transport networks. Y6 also consistently shows higher electronic couplings for LUMOs, HOMOs, and local excitations than ITIC-type acceptors, which results in fast transport rates for electrons, holes, and excitons. Importantly, when considering dimers, their configurations in Y6 are more diverse than in ITIC-type acceptors, with many of those similar to the configurations observed in the Y6 crystal structure reported recently. Most Y6 dimer configurations exhibit strong binding interactions, large electronic couplings, and high transport rates, which when taken together rationalize the better performance of OSCs based on Y6.

几年前，Y6 已成为有机太阳能电池的主要非富勒烯受体之一，因为它的使用可带来卓越的功率转换效率。因此，研究导致 Y6 功效的多尺度现象具有重要意义。在这里，我们使用密度泛函理论计算和分子动力学模拟的组合对 Y6 和早期非富勒烯受体 IT-4F 和 ITIC 的纯薄膜进行建模，以研究控制其电荷和激子传输速率的各种因素。我们发现 Y6 中的分子堆积与 IT-4F 和 ITIC 中的分子堆积截然不同。在纳米尺度上，Y6 的局部形态由大量定向的面堆垛和连接良好的运输网络。Y6 还始终显示出比 ITIC 型受体更高的 LUMO、HOMO 和局部激发的电子耦合，这导致电子、空穴和激子的传输速率更快。重要的是，当考虑二聚体时，它们在 Y6 中的配置比 ITIC 型受体中的配置更加多样化，其中许多与最近报道的 Y6 晶体结构中观察到的配置相似。大多数 Y6 二聚体配置表现出强结合相互作用、大电子耦合和高传输速率，将这些结合起来使基于 Y6 的 OSC 具有更好的性能。