Polymer solar cells (PSCs) based on polymer donors and nonfullerene small molecule acceptors are a very attractive technology for solar energy conversion, and their performance is heavily determined by film morphology. It is of considerable interest to reveal instructive morphology–performance relationships of these blends. This feature article discusses the recent advances in analysing the morphology formation of nonfullerene PSCs with an effective polymer thermodynamic quantity, i.e., Flory–Huggins interaction parameter χ. In particular, guidelines of high and low χ systems are summarized. The fundamental understanding of χ and its correlations to film morphology and photovoltaic device parameters is of utmost relevance for providing essential material design criteria, establishing suitable morphology processing guidelines, and thus advancing the practical applications of PSCs based on nonfullerene acceptors.

中文翻译：

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热力学相互作用参数对指导聚合物：非富勒烯太阳能电池优化的意义。

基于聚合物供体和非富勒烯小分子受体的聚合物太阳能电池（PSC）是一种非常有吸引力的太阳能转化技术，其性能在很大程度上取决于薄膜的形态。揭示这些混合物具有指导意义的形态与性能之间的关系非常重要。这篇专题文章讨论了在分析具有有效聚合物热力学量即弗洛里-哈金斯相互作用参数χ的非富勒烯PSC的形态形成方面的最新进展。特别是，总结了高和低χ系统的准则。对χ的基本理解 其与薄膜形态和光伏器件参数的相关性对于提供基本的材料设计标准，建立合适的形态处理准则，从而促进基于非富勒烯受体的PSC的实际应用至关重要。