Bridgehead Imine Substituted Cyclopentadithiophene Derivatives: An Effective Strategy for Band Gap Control in Donor–Acceptor Polymers

Bridgehead imine substituted cyclopentadithiophene structural units offer the opportunity to modify the electronic properties, in particular, the HOMO–LUMO energy levels of donor–acceptor polymers with unprecedented precision. Utilizing a common synthetic pathway, copolymers with high average molecular weights, a variety of functionality, and properties suitable for solar cell incorporation can be generated. The fabrication of organic photovoltaic devices with these new materials is demonstrated.