Fluorene–Dithienothiophene-S,S-dioxide Copolymers. Fine-Tuning for OLED Applications

Abstract

Three groups of fluorene–dithieno[3,2-b;2′,3′-d]thiophene-S,S-dioxides (DTT-S,S-dioxide) copolymers, each having four different ratios of DTT-S,S-dioxide (5, 15, 25, and 50%) were successfully synthesized through Suzuki coupling method. While the first group copolymers P1 had direct connection of fluorene to the peripheral thiophenes of DTT-S,S-dioxide, second group copolymers P2 had a thiophene extension between fluorene and DTT-S,S-dioxide, and in the third group, copolymers P3, fluorene had a connection with DTT-S,S-dioxide through the phenyl moiety of DTT. Absorbance and emission measurements of first two groups P1 and P2 displayed a regular bathochromic shift with increasing content of DTT-S,S-dioxide, which was more clearly observed in their solid state fluorescence measurements. Introduction of thiophene to the peripherals of the DTT-S,S-dioxide in copolymers P2 caused even further bathochromic shift in absorbances and emissions. As the absorbance and emission of P1 went up to 447 and 558 nm in sol...