New tunable thieno[3,4-b]pyrazine-based materials

The effect of electron-donating and electron-withdrawing side chains on the electronic properties of thieno[3,4-b]pyrazines and their corresponding homopolymers have been investigated. Contrary to common trends in polythiophene materials, the addition of electron-donating groups results in higher HOMO–LUMO energies in the monomers and higher Eg values in the resulting polymers. The use of electron-withdrawing groups, however, provides reduced HOMO–LUMO energies and lower Eg values. The application of electron-withdrawing functionalized thieno[3,4-b]pyrazines appears to be a promising new approach for the production of low Eg materials.