Synthesis and characterization of blue light emitting redox-active polyimides bearing a noncoplanar fused carbazole–triphenylamine unit

Abstract

A series of novel redox-active polyimides bearing unsymmetrical and noncoplanar carbazole units have been synthesized as future hole transporting materials. These polyimides were derived from a novel diamine monomer N¹-(4-aminophenyl)-N¹-(9-ethyl-9H-carbazol-3-yl)benzene-1,4-diamine, which was, in turn, synthesized by N-arylation of 9-ethyl-9H-carbazole-3-amine with 4-fluoro-1-nitrobenzene. The structures of the prepared monomer and polyimides were thoroughly characterized using CHNS, FTIR, and NMR spectroscopic techniques. Similarly, their thermal, optical, fluorescence, and electrochemical properties were measured using DSC, TGA, UV-Vis spectroscopy, photoluminescence spectroscopy, TCSPC and cyclic voltammetry, which revealed that the synthesized polyimides exhibit high lying HOMO levels, blue light emission, and stable electrochemical properties. Thus, these properties make our synthesized polyimides potential candidates for hole transporting materials in organic light emitting diodes (OLEDs).