New multifunctional blue-emissive materials with superior thermal properties, viz., 4,4′-bis(1-(4-naphthyl)-1 H -phenanthro[9,10- d ]imidazol-2-yl)binaphthyl (NPIBN), 4,4′-bis(1-(4-cyanonaphthyl)-1 H -phenanthro[9,10- d ]imidazol-2-yl)biphenyl (CNPIBP), and 4,4′-bis(1-(4-cyanonaphthyl)-1 H -phenanthro[9,10- d ]imidazol-2-yl)binaphthyl (CNPIBN) have been synthesized. The said molecules show high photoluminescence quantum yield (Φ s/f : NPIBN-0.75/0.68, CNPIBP-0.85/0.76, and CNPIBN-0.90/0.88). The fabricated nondoped/doped device with CNPIBN/4,4′-bis(carbazol-9-yl)biphenyl: CNPIBN display maximum efficiencies (η ex 4.96/5.4%; η c 7.46/7.56 cd A –1 ; η p 6.85/6.91 lm W –1 ) at low turn-on voltage (3.5/3.8 V). Nondoped devices based on D−π–A architecture, 4-(2-(5-(9 H -carbazol-9-yl)thiophen-2-yl)-1 H -phenanthro[9,10- d ]imidazol-1-yl)naphthalene-1-carbonitrile exhibit maximum efficiencies (η ex 2.32%; η c 4.00 cd A –1 ; η p 3.42 lm W –1 ) compared to 4-(2-(5-(4-(diphenylamino)phenyl)thiophen-2-yl)-1 H -phenanthro[9,10- d ]imidazol-1-yl)naphthalene-1-carbonitrile (η ex 2.01%; η c 3.89 cd A –1 ; η p 3.15 lm W –1 ).

Efficient blue emitters, 1-(2,3-dihydrobenzodioxinyl)-2-naphthylphenanthroimidazole, 1-(2,3-dihydrobenzodioxinyl)-2-methoxynaphthylphenanthroimidazole and 1-(2,3-dihydrobenzodioxinyl)-2-pyrenylphenanthroimidazole have been reported.

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The new blue light emitting materials, (E)-4 0 -(1-(4-(2-(1-(naphthalen-1-yl)-1H-phenanthro [9,10- ; h p 5.10 lm W À1) at low turn-on voltage and the device performances show that the phenanthroimidazole unit is a tunable building block for carrier injection properties and that they also can be used as hosts for green phosphorescent OLEDs.

SMPI-Cz:Ir(ppy)3-based devices exhibit a luminance of 20 725 cd m−2, ηc of 61.4 cd A−1 and ηp of 63.8 lm W−1.

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