In the present study, we report the synthesis of a series of anthracene based polyfluorenes containing alkyl substituted 9,10-diphenylanthracene and hydrazone substituted fluorene moieties. The polymers were synthesized via copper catalysed Ullmann coupling, which comparatively is inexpensive as compared to palladium and platinum used in Suzuki coupling. The synthesized polymers were characterized by various spectroscopic techniques. All the polymers exhibited blue emission having band gap in the range of 2.7-2.83 eV. The polymers showed good thermal stability with decomposition temperature over 330 °C and glass transition temperature in the range of 125-140 °C. All the polymers were soluble in common organic solvents with weight average molecular weight in the range of 21,000-25,000. The electrochemical study reveals that the HOMO energy levels of the polymers were in the range of − 5.16 to − 5.26 eV which had elevated compared with that of polyfluorene (5.7 eV). It matched the work function of ITO and ITO/PEDOT: PSS (4.7 and 5.0 eV respectively). These results indicated that the synthesized polymers could be promising materials for applications in light emitting diode.

A set of anthracene containing polyfluorenes (PFs) having 9,10-diphenylanthracene with alkyl substituents and aniline containing fluorenes were prepared. Commonly, light-emitting polymers were synthesized using expensive palladium-like catalysts. In the present work, palladium was replaced by copper as a cost-effective PF synthesis catalyst, which is also suitable for large-scale polymer synthesis. Synthesized PFs emit light in the blue region with a bandgap of 2.87–2.90 eV. Thermally stable PFs had a decomposition temperature of more than 305°C and a glass transition temperature of 125–138°C. PFs were soluble in organic solvents and had a molecular weight of around 21,700–25,500. The electrochemical study of these PFs showed low level of highest occupied molecular orbital (HOMO) energy of −5.16 to −5.26 eV, which was significantly higher than that of PF (5.7 eV). These findings suggested that the resulting PFs could be used as a component of the light-emitting diode.

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5,8-Dibromo-13,13-bis(alkyl)dibenzofluorene derivatives functionalized with different alkyl molecules [M2a-M2f ] and 2-tert butyl-9,10-di (p-hydroxyphenyl) anthracene [M1b], were designed to research the impact of molecular structure on the optical properties of polymer. Polymers were synthesized by aromatic nucleophilic substitution in moderate to strong yields (60-65%). After structural characterization through several techniques (e.g. FTIR, 1 H, and 13 C-NMR), special emphasis was put on the study of their optical properties through UV-Vis and photoluminescence spectroscopy. The polymers demonstrated strong thermal stability up to 350 °C and high glass transition temperature (108-133 °C). All of the polymers showed blue emission within a range of 416-433 nm and had a band gap of 2.87-2.99 eV. The electrochemical study reveals that, HOMO levels for polymers were estimated in the range of − 5.22 to − 5.26 eV and LUMO of − 2.23 to − 2.38 eV. The polymers demonstrated strong thermal stability and blue emission within a range of 416-433 nm. These polymeric materials have demonstrated high photoluminescence which may be useful for future display applications as a good source.

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