ma071126k_si_001.pdf (117.4 kB)
Substituent Effect on the Optoelectronic Properties of Alternating Fluorene-Thiophene Copolymers
journal contribution
posted on 2007-11-13, 00:00 authored by Bikash Pal, Wei-Che Yen, Jye-Shane Yang, Wei-Fang SuA novel series of soluble alternating conjugated copolymers, comprised of 9,9-dihexylfluorene
and thiophene or substituted thiophene moieties (P1−P5), were synthesized via the palladium-catalyzed Suzuki
coupling reaction. Substitutents on the thiophene include the electron-donating groups of hexyl and hexyloxymethyl
group and the electron-withdrawing groups of hexyl carboxylate and cyano. The steric effects of the bulkier
substituents outweigh the electronic effects of the substituents on the observed absorption and photoluminescence
properties of the copolymers. Therefore, only the cyano substituted copolymer (P4) exhibits a red shift of the
electronic spectra with 1.6 times enhancement in the fluorescence quantum yield as compared with the unsubstituted
copolymer (P5). The substituents slightly reduce the values of Tg and Td of P5, but all of the reported copolymers
have a Td larger than 300 °C.