Resolving Atomic-Scale Interactions in Nonfullerene Acceptor Organic Solar Cells with Solid-State NMR Spectroscopy, Crystallographic Modelling, and Molecular Dynamics Simulations

Benjamin R. Luginbuhl, Parth Raval, Tomasz Pawlak, Zhifang Du, Tonghui Wang, Grit Kupgan, Nora Schopp, Sangmin Chae, Sangcheol Yoon, Ahra Yi, Hyo Jung Kim, Veaceslav Coropceanu, Jean Luc Brédas, Thuc Quyen Nguyen, G. N.Manjunatha Reddy

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Fused-ring core nonfullerene acceptors (NFAs), designated “Y-series,” have enabled high-performance organic solar cells (OSCs) achieving over 18% power conversion efficiency (PCE). Since the introduction of these NFAs, much effort has been expended to understand the reasons for their exceptional performance. While several studies have identified key optoelectronic properties that govern high PCEs, little is known about the molecular level origins of large variations in performance, spanning from 5% to 18% PCE, for example, in the case of PM6:Y6 OSCs. Here, a combined solid-state NMR, crystallography, and molecular modeling approach to elucidate the atomic-scale interactions in Y6 crystals, thin films, and PM6:Y6 bulk heterojunction (BHJ) blends is introduced. It is shown that the Y6 morphologies in BHJ blends are not governed by the morphology in neat films or single crystals. Notably, PM6:Y6 blends processed from different solvents self-assemble into different structures and morphologies, whereby the relative orientations of the sidechains and end groups of the Y6 molecules to their fused-ring cores play a crucial role in determining the resulting morphology and overall performance of the solar cells. The molecular-level understanding of BHJs enabled by this approach will guide the engineering of next-generation NFAs for stable and efficient OSCs.

Original languageEnglish (US)
Article number2105943
JournalAdvanced Materials
Volume34
Issue number6
DOIs
StatePublished - Feb 10 2022

Keywords

  • bulk heterojunction
  • morphology
  • nonfullerene acceptor solar cells
  • organic semiconductors
  • packing interactions
  • polymers
  • self-assembly

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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