A Spray-Processable, Low Bandgap, and Ambipolar Donor-Acceptor Conjugated Polymer

Combining a strong donor, tris(dodecyloxy)phenyl)-dithieno[3,2-b:2',3'-d]pyrrole, with a strong acceptor, 4,8-dithien-2-yl-2 lambda(4)delta(2)-benzo[1,2-c;4,5-c']bis[1,2,5]thiadiazole, has yielded the lowest bandgap, soluble, spray-processable polymer to date. The polymer has access to four different redox states and shows ambipolar behavior in OFETs. Multiple techniques, including transmission/absorption spectroscopy on SWCNTs and reflectance spectroscopy on gold were used to accurately estimate the optical bandgap at 0.5-0.6 eV, which correlates well to theoretical calculations.