Synthesis, photophysical and electroluminescent properties of blue-emitting dual core imidazole–anthracene/pyrene derivatives

Abstract

Two blue emitting dual core materials consisting of phenanthroimidazole and anthracene or pyrene chromophores were designed and synthesized. 2-(9-Anthracenyl)-1-(4-tert-butylphenyl)-1H-phenanthro[9,10-d]imidazole (1) and 2-(1-pyrenyl)-1-(4-tert-butylphenyl)-1H-phenanthro[9,10-d]imidazole (2) were easily synthesized and used as emitters in nondoped OLEDs. Devices based on 1 and 2 show low turn-on voltages (as low as 2.6 and 2.5 V) and stable blue emissions with CIE of (0.16, 0.17) and (0.15, 0.12), respectively. The maximum current efficiencies of 1.15 and 0.90 cd A⁻¹ and maximum external quantum efficiencies of 0.83% and 0.85% with little efficiency roll-off at high current densities were achieved, respectively.