White polymer light emitting diode materials introducing dendritic quinoxaline derivative: Synthesis, optical and electroluminescent properties

• We synthesized the dendritic quinoxaline as an orange dopant.
• The synthesized PFDTQ polymer series showed good solubility and thermal stability.
• PL intensities of the dendritic TQ increased with the generation number of the dendrons.
• Polymers of PFDTQ1G05 and PFDTQ2G10 showed white color emission.

Copolymers including dendritic-quinoxaline (DTQ1G, DTQ2G) (<0.1 mol%) as dopant derivative have been synthesized on a polyfluorene (PF) backbone based on the Suzuki coupling reaction. The UV–vis spectra of polymers showed similar behaviors in the solution and on the film. However, PL spectra were similar to that of PF in solution, but the peak around 590 nm increased as the amounts of DTQ1G and DTQ2G were increased in the casting film. In thin film, the intensities of the dendritic TQ monomers increased with the generation number of the dendrons. In case of PFDTQ2G03, the luminous efficiency and power efficiency were 0.66 cd/A and 0.29 lm/W, respectively with a maximum brightness of 3792 cd/m2. The CIE coordinates of PFDTQ1G05 and PFDTQ2G10 were (0.33, 0.30) and (0.35, 0.34) close to the pure white coordinates of (0.33, 0.33).

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