Although it is known that molecular interactions govern morphology formation and purity of mixed domains of conjugated polymer donors and small-molecule acceptors, and thus largely control the achievable performance of organic solar cells, quantifying interaction–function relations has remained elusive. Here, we first determine the temperature-dependent effective amorphous–amorphous interaction parameter, χ_aa(T), by mapping out the phase diagram of a model amorphous polymer:fullerene material system. We then establish a quantitative ‘constant-kink-saturation’ relation between χ_aa and the fill factor in organic solar cells that is verified in detail in a model system and delineated across numerous high- and low-performing materials systems, including fullerene and non-fullerene acceptors. Our experimental and computational data reveal that a high fill factor is obtained only when χ_aa is large enough to lead to strong phase separation. Our work outlines a basis for using various miscibility tests and future simulation methods that will significantly reduce or eliminate trial-and-error approaches to material synthesis and device fabrication of functional semiconducting blends and organic blends in general.

尽管已知分子相互作用决定了共轭聚合物供体和小分子受体混合域的形态形成和纯度，从而在很大程度上控制了有机太阳能电池的可实现性能，但量化相互作用-功能关系仍然难以捉摸。在这里，我们首先通过绘制模型无定形聚合物：富勒烯材料系统的相图来确定与温度相关的有效无定形-无定形相互作用参数χ _aa ( T )。然后，我们在χ _aa之间建立一个定量的“恒定扭结饱和度”关系以及有机太阳能电池中的填充因子，在模型系统中进行了详细验证，并在包括富勒烯和非富勒烯受体在内的众多高性能和低性能材料系统中进行了描述。我们的实验和计算数据表明，只有当χ _aa大到足以导致强相分离时，才能获得高填充因子。我们的工作概述了使用各种混溶性测试和未来模拟方法的基础，这些方法将显着减少或消除功能性半导体共混物和有机共混物的材料合成和器件制造的试错方法。