Very narrow band gap donor-acceptor (DA) conjugated polymers demonstrate complex and unique electronic properties. Developing an understanding of the interplay between chemical and electronic structure in these systems will require control of the frontier orbital energetics (separation, position, and alignment), ground state configurations, interchain arrangements, solid-state properties, and many other molecular features with synthetic precision that has yet to be demonstrated. Cross-conjugated 4H-cyclopenta[2,1-b:3,4-b′]dithiophene (CPDT) structural units, in combination with strong acceptors with progressively delocalized π-systems, afford modular DA copolymers with broad and long wavelength light absorption that spans technologically relevant wavelength (λ) ranges from 0.7 &lt; λ &lt; 3.2 μm (Egap &lt; 0.5 eV). These solution-processable materials possess some of the narrowest band gaps reported to date and illustrate how incorporation of peripheral cross-conjugated substituents within a π-conjugated system provides a much more complex, versatile, and highly valuable tool for the tuning of material properties. Such control has also resulted in unanticipated physical properties, such as intrinsic electrical conductivity. Quantum chemical calculations indicate that further band gap narrowing is achievable, affording polymers that can interact with a substantially larger portion of the electromagnetic spectrum, and indicated that unique spin, thermoelectric, and magnetic phenomena are present and/or accessible. Of primary significance is that these properties are highly dependent on the functionality, molecular configuration, and building blocks employed, thereby affording new paradigms for the rational generation of materials with novel physical properties.

Donor-acceptor conjugated polymers with modular electronic properties and very narrow band gaps

249th National Meeting (2015)

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