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Molecular Acceptors Based on a Triarylborane Core Unit for Organic Solar Cells
Author(s) -
Yu Yingjian,
Meng Bin,
Jäkle Frieder,
Liu Jun,
Wang Lixiang
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904178
Subject(s) - planarity testing , organic solar cell , stacking , homo/lumo , substituent , materials science , acceptor , steric effects , molecule , electron acceptor , band gap , organic semiconductor , photochemistry , solar cell , crystallography , chemistry , polymer , stereochemistry , optoelectronics , organic chemistry , physics , composite material , condensed matter physics
Triarylboranes that exhibit p–π* conjugation serve as versatile building blocks to design n‐type organic/polymer semiconductors. A series of new molecular acceptors based on triarylborane is reported here. These molecules are designed with a boron atom that bears a bulky 2,4,6‐tri‐ tert ‐butylphenyl (Mes*) substituent at the core and strong electron‐withdrawing 2‐(3‐oxo‐2,3‐dihydroinden‐1‐ylidene)malononitrile (IC) units as the end‐capping groups that are linked to the core by bithiophene bridges. Butyl or butoxy groups are introduced to the bithiophene units to tune the optoelectronic properties. These molecules show nearly planar backbones with highly localized steric hindrance at the core, low LUMO/HOMO energy levels, and broad absorption bands spanning the visible region, which are all very desirable characteristics for use as electron acceptors in organic solar cell (OSC) applications. The attachment of butyl groups to the bithiophene bridges brings about a slightly twisted backbone, which in turn promotes good solubility and homogeneous donor/acceptor blend morphology, whereas the introduction of butoxy groups leads to improved planarity, favorable stacking in the film state, and a greatly reduced band gap. OSC devices based on these molecules exhibit encouraging photovoltaic performances with power conversion efficiencies reaching up to 4.07 %. These results further substantiate the strong potential of triarylboranes as the core unit of small molecule acceptors for OSC applications.