Photo- and Electroluminescent Properties of Polymethacrylates with Carbazolyl and Fluorescent Pendant Groups

Because polymeric materials have recently found widespread use in light-emitting devices, we decided to exploit a novel group of copolymers as active materials in such devices and managed to obtain polymeric electroluminescent diodes emitting blue light. The electroluminescent devices were fabricated using the copolymers composed of 2-(carbazol-9-yl)ethyl methacrylate (CEM) and 3-phenyl-7-methacryloyloxyethoxy-1-methyl-1H-pyrazolo[3,4-b]-quinoline (MEPQ). The concentration of MEPQ in the copolymers was kept at a low level and changed from 0.5, 1, 2, 5 to 8 mol %. The turn-on voltage for light emission was 8 V. It was found that the emission peaks of the electroluminescent devices were blue-shifted by ≈9 nm in comparison to photoluminescence spectra of the copolymers in thin film. Moreover, as the concentration of MEPQ in the copolymers was increased from 0.5 to 8 mol %, the photoluminescence emission peaks shifted slightly to the red from 447 to 455 nm, while the electroluminescence emission peaks moved f...