Abstract
Introducing solubilizing α-branched alkyl chains on a poly(diketopyrrolopyrrole-alt-terthiophene) results in a dramatic change of the structural, optical, and electronic properties compared to the isomeric polymer carrying β-branched alkyl side chains. When branched at the α-position the alkyl substituent creates a steric hindrance that reduces the tendency of the polymer to π–π stack and endows the material with a much higher solubility in common organic solvents. The wider π–π stacking and reduced tendency to crystallize, evidenced from grazing-incidence wide-angle X-ray scattering, result in a wider optical band gap in the solid state. In solar cells with a fullerene acceptor, the α-branched isomer affords a higher open-circuit voltage, but an overall lower power conversion efficiency as a result of a too well-mixed nanomorphology. Due its reduced π–π stacking, the α-branched isomer fluoresces and affords near-infrared light-emitting diodes emitting at 820 nm.
Original language | English |
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Pages (from-to) | 14221-14228 |
Number of pages | 8 |
Journal | Chemistry - A European Journal |
Volume | 26 |
Issue number | 62 |
DOIs | |
Publication status | Published - 6 Nov 2020 |
Keywords
- aggregation
- light-emitting diodes
- organic solar cells
- polymer semiconductors
- thin film