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H‐Bonds‐Assisted Molecular Order Manipulation of Nonfullerene Acceptors for Efficient Nonannealed Organic Solar Cells
Author(s) -
Liu Xuan,
Wang Xuchao,
Xiao Yejun,
Yang Qing,
Guo Xin,
Li Can
Publication year - 2020
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201903650
Subject(s) - crystallinity , stacking , hydrogen bond , intermolecular force , materials science , conjugated system , organic solar cell , miscibility , acceptor , polymer , crystallography , molecule , chemistry , organic chemistry , composite material , physics , condensed matter physics
Abstract Various substituents have been incorporated into nonfullerene acceptors (NFAs) to modulate absorption scopes and energy levels for boosting efficiencies of organic solar cells (OSCs). The manipulation of the NFAs' molecular order and crystallinity via those substitutions is equally crucial to OSC performances, which yet remains interesting and challenging. The hydroxyl group, which can potentially form strong intermolecular hydrogen bonds (H‐bonds) for improving molecular arrangements, has, however, never been considered. Herein, two hydroxyl‐functionalized NFAs, IT‐OH with one hydroxyl and IT‐DOH with two hydroxyls, are synthesized to tune the molecular packing and crystallinity. The ordered molecular arrangement and higher crystallinity are observed for the IT‐OH and IT‐DOH than the parent ITIC. This is assigned to the formation of intermolecular H‐bonds induced by the hydroxyls, which elongates molecular conjugated planes leading to long‐range‐ordered structures via π–π stacking. By the appropriate crystallinity and miscibility with donor polymer, an IT‐DOH‐based nonannealed OSC affords an efficiency of 12.5% with good device stability. This work provides a promising strategy to tune the molecular packing and crystallinity to design NFAs by introducing hydroxyl groups.