Novel low-band-gap conjugated polymers using an alternating donor/acceptor repeat unit

• Published in: e-Polymers 2010-12, Vol.10 (1), p.774-788
• Main Authors: Piyakulawat, Phimwipha, Keawprajak, Anusit, Chindaduang, Anon, Helfer, Anke, Asawapirom, Udom
• Format: Article
• Language: English
• Subjects: donor-acceptor polymer; low band gap polymer; naphthalene-bisimide
• ISSN: 2197-4586; 1618-7229; 1618-7229
• DOI: 10.1515/epoly.2010.10.1.774

A series of new π-conjugated donor-acceptor copolymers, based on a naphthalene-bisimide moiety as the electron-acceptor and connected to either thiophene or dialkylfluorene as the electron-donor, were synthesized. The polymers are soluble in common organic solvents. The UV-Vis spectra of the copolymers in chloroform showed two absorption maxima at higher energies (ca. 301 - 364 nm), assigned to the π-π * transition, and at a lower energy (ca. 512 - 595 nm), ascribed to the intramolecular charge transfer between donor and acceptor units. Cyclic voltammetry revealed that the polymers were susceptible to both electrochemical oxidation and reduction, and they had a LUMO and HOMO levels ranging from -4.07 to -3.80 eV and -6.13 to -5.64 eV, respectively. The energy band gaps were estimated to be 1.48 - 2.06 eV. These results represent a positive step towards making novel compounds suitable for electronic applications.