Synthesis, characterization, photophysics and electroluminescence based on a series of pyran-containing emitters

Four unsymmetric as well as symmetric carbazole or oxadiazole modified pyran-containing compounds have been synthesized and characterized. These compounds are 4-(dicyanomethylene)-2-methyl-6-(4-(carbazolo-9-yl)phenyl)-4H-pyran (10), 4-(dicyanomethylene)-2,6-bis(4-(carbazolo-9-yl)phenyl)-4H-pyran (11), 4-(dicyanomethylene)-2-methyl-6-(4-tert-phenyl)-1,3,4-oxdiazole-4-phenyl)-4H-pyran (12), and 4-(dicyanomethylene)-2,6-bis(4-tert-phenyl)-1,3,4-oxdiazole-4-phenyl-4H-pyran (13). Photoluminescent measurements indicated that their maximal emissions can be tuned from 543 to 590 nm in acetone solution. Electroluminescent studies based on these compounds as dopants resulted in greenish yellow light emission. It was found that the device based on the bis-condensed symmetric compound (11) with the configuration of indium tin oxide / Copper (II) phthalocyanine (5 nm) / N,N′-bis-(1-naphthl)-diphenyl-1,1′-biphenyl-4,4′-diamine (40 nm) / compound (11) : tris-(8-quinolinolato)aluminium (Alq₃) (1%) (30 nm) / 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (5 nm) / Alq₃ (40 nm) / Mg : Ag (9 : 1) (200 nm) / Ag (80 nm) has achieved the highest luminance (6869 cd/m²) and efficiency (1.32 lm/W and 2.52 cd/A) among the four emitters.