Novel Fluorene-Thiophene Copolymers: Synthesis,Photophysical and Electrochemical Properties

Summary: Novel alternating fluorene - thiophene copolymers, F3HT, FIPT , and FPyT , consisting of 9,9-dihexylfluorene and 3-substituted (with hexyl, 3-methylbutyl and 2-(pyren-1-yl)vinyl, respectively) thiophene units were synthesized. Photoluminescence (PL) and electrochemical behavior of these polymers were studied. PL behavior of FPyT polymer differed from that of the other copolymers. Thin films of F3HT and FIPT showed an intense green PL emission whereas the PL emission of FPyT thin films was orange. The PL emission spectra in thin films differ from those measured in THF solutions. Aggregate formation played an important role in the solid state. The aggregation was more pronounced with FPyT than with F3HT and FIPT thin films. In all polymers reversible oxidation and reduction were observed. Similar values of ionization potentials and electron affinities were estimated for F3HT and FIPT , but a higher value of electron affinity for FPyT .