Efficiencies of organic solar cells have practically doubled since the development of non-fullerene acceptors (NFAs). However, generic chemical design rules for donor-NFA combinations are still needed. Such rules are proposed by analyzing inhomogeneous electrostatic fields at the donor–acceptor interface. It is shown that an acceptor–donor–acceptor molecular architecture, and molecular alignment parallel to the interface, results in energy level bending that destabilizes the charge transfer state, thus promoting its dissociation into free charges. By analyzing a series of PCE10:NFA solar cells, with NFAs including Y6, IEICO, and ITIC, as well as their halogenated derivatives, it is suggested that the molecular quadrupole moment of ≈75 Debye Å balances the losses in the open circuit voltage and gains in charge generation efficiency.

中文翻译：

---

有机太阳能电池中非富勒烯受体的化学设计规则

自非富勒烯受体 (NFA) 的发展以来，有机太阳能电池的效率实际上已经翻了一番。然而，仍然需要供体-NFA 组合的通用化学设计规则。这些规则是通过分析供体-受体界面处的非均匀静电场而提出的。结果表明，受体-供体-受体分子结构以及平行于界面的分子排列会导致能级弯曲，使电荷转移状态不稳定，从而促进其解离为自由电荷。通过分析一系列 PCE10:NFA 太阳能电池，包括 Y6、IEICO 和 ITIC 在内的 NFA 及其卤代衍生物，表明 ≈75 Debye Å 的分子四极矩平衡了开路电压和电荷产生效率的提高。