For conjugated polymers, bandgap reduction is perhaps the most common target of molecular tuning, with the utilization of donor-acceptor (D-A) frameworks most often applied for the production of low bandgap (Eg &lt; 1.5 eV) and reduced bandgap (Eg = 1.5-2.0 eV) polymers. Such D-A frameworks employ alternating electron-rich and electron-deficient moieties in order to produce a hybrid material with HOMO levels characteristic of the donor and LUMO levels characteristic of the acceptor, with the goal of reducing the HOMO-LUMO energy and achieving a lower bandgap. The widespread application of such frameworks has resulted in various assumptions and misconceptions in the literature, including the view that monomers act exclusively as donors, acceptors, or neutral spacers. At odds with this, however, is the discovery that thieno[3,4-b]pyrazines (TPs), a commonly applied class of acceptors, also exhibit properties of very strong donors, leading to their current description as ambipolar units. As TPs exhibit a high-lying HOMO, this should allow for a new design model in which TP units are paired with an acceptor, rather than the traditional pairing with a donor. Several such ambipolar-acceptor frameworks have now been successfully produced via direct arylation polymerization to give materials with bandgaps of 0.97-1.12 eV. The synthesis and characterization of such ambipolar-acceptor frameworks will be presented, along with discussions of other potential ambipolar units and the potential broader applications of this new design paradigm.

Deviate from the norm: A new design paradigm for low bandgap polymers via donor-acceptor frameworks

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.