Synthesis and optoelectronic properties of a red emitting branched polymer containing V-shaped oligothiophene-S,S-dioxides as repeating units

The synthesis, optical characterization and redox potentials of a branched polythiophene (V-PT), obtained by the Stille polycondensation of V-shaped 2,3-dibromo-benzo[b]thiophene-1,1-dioxide and 3,3-dimethyl-5,5′-tributylstannyl-2,2′-bithiophene, are reported. The branched shape favours the suppression of aggregation effects and the presence of the benzo[b]thiophene-1,1-dioxide moiety leads to a marked increase in electron affinity. A single layer light-emitting diode having V-PT as the active material showed a luminance of 948 cd m−2 .

The branched polymer V-PT containing a V-shaped oligothiophene-S,S-dioxide as the repeating unit shows good processability, high electron affinity and red emission in thin films. V-PT was effectively employed for the preparation of a LED that displayed the highest luminance (948 cd m−2) measured so far, for polymers containing the thienyl-S,S-dioxide unit.