Molecular Acceptors Based on a Triarylborane Core Unit for Organic Solar Cells

Abstract

Triarylboranes that exhibit p-p*c onjugations erve as versatile building blocks to designn -type organic/polymer semiconductors. As eries of new molecular acceptors based on triarylborane is reported here. These molecules are designed with ab oron atom that bears ab ulky 2,4,6-tri-tertbutylphenyl (Mes*)s ubstituenta tt he core ands trong electron-withdrawing2 -(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 highlyl ocalized steric hindrance at the core, low LUMO/HOMO energy levels,a nd broad absorption bandss panning the visible region,w hich are all very desirable characteristics for use as electron acceptors in organic solar cell (OSC) applications.T he attachment of butyl groups to the bithiophene bridgesb rings aboutaslightly twisted backbone, which in turn promotes good solubility and homogeneous donor/acceptor blend morphology,w hereas the introduction of butoxy groupsl eads to improved planarity, favorable stacking in the film state,a nd ag reatlyr educed band gap. OSC devices basedonthesemolecules exhibit encouraging photovoltaic performances with powerc onversion efficiencies reaching up to 4.07 %. These resultsf urther substantiate the strong potential of triarylboranes as the core unit of small molecule acceptors for OSC applications.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

1,4-Azaborine based unfused non-fullerene acceptors for organic solar cells

“…2b, the HOMO energy level was mainly delocalized on the core dithieno-1,4-azaborine and alkoxyl thiophene moieties, whereas the LUMO energy level was distributed along the whole molecule, indicating efficient p–π* conjugation between boron atoms with adjacent thiophenes. 47 The calculated HOMO/LUMO was −5.99/−3.94 eV. The discrepancy between DFT calculation results and CV measurements may be derived from the intermolecular packing of ABBT-BO / ABBT-DT that was generally ignored in the calculations.…”

Strategical design and synthesis of D–A–D-based quinolines for improved WORM memory performance

“…These could give a profound understanding of the structure-property relationship of such terminal groups to create a balance between the optimum threshold voltage and better memory performance. (i) tert -Butylphenyl groups owing to the electron-donating nature can contribute to the larger steric effect controlling the intermolecular interactions in the molecules 19 (ii) CN and CHO along with their electron-withdrawing effect can lower the HOMO–LUMO levels of the molecules. 20 Altogether these terminal groups could alter the energy levels and thereby the electrical conductivity of the organic semiconductors.…”

Fully-unfused electron acceptors based on a steric boron dipyrromethene (BODIPY) core for organic solar cells

“…[34][35][36] Introducing steric hindrance is a widely employed approach to twist the molecular skeleton, further hindering excessive intermolecular stacking to a certain extent. 37,38 For FUEAs, herein, the steric units on the BODIPY core can rotate the molecular backbones by inducing steric hindrance. Hence, the twisted and spatial geometries of FUEAs might be favorable for constituting proper intermolecular stacking intensities in BHJ blends.…”