Isoindigo has been extensively used to synthesize donor-acceptor materials for organic photovoltaics; however, there have been only a few purely n-type materials made from the isoindigo core. Poly(isoindigo) was the first isoindigo-based n-type material. It exhibited an extremely low electron mobility due to a lack of planarity in the polymer backbone. We have recently synthesized poly(isoindigo-alt-ethynylene) and poly(bisisoindigo), two new polymers in the isoindigo family. These polymers were chosen with the goal of improving the electron mobility. In the isoindigo-alt-ethynylene copolymer, the sterically unencumbered ethynyl spacer helps reduce the torsional angle between adjacent isoindigo units and conserve planarity in the polymer backbone. Two lactam rings in bisisoindigo lower the energy of the lowest unoccupied molecular orbital to produce a better energy offset between frontier molecular orbitals of donor and acceptor. This poster will discuss the effect of modified cores on the optoelectronic properties and photovoltaic performance of the polymers.

Effect of torsional angle on the optoelectronic properties of isoindigo-based polymers

256th National Meeting (2018)

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