Quantitative relations between interaction parameter, miscibility and function in organic solar cells

Long Ye, Huawei Hu, Masoud Ghasemi, Tonghui Wang, Brian A. Collins, Joo Hyun Kim, Kui Jiang, Joshua H. Carpenter, Hong Li, Zhengke Li, Terry McAfee, Jingbo Zhao, Xiankai Chen, Joshua Lin Yuk Lai, Tingxuan Ma, Jean Luc Bredas, He Yan, Harald Ade

Research output: Contribution to journalArticlepeer-review

373 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)253-260
Number of pages8
JournalNature materials
Volume17
Issue number3
DOIs
StatePublished - Mar 1 2018
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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