Publications by authors named "Sekar Sivaraj"

Aromatically substituted phenanthroimidazoles at the C6 and C9 positions enhanced the thermal, photochemical and electroluminescence properties due to extension of conjugation. These new materials exhibit good photophysical properties with high thermal stability, good film-forming property and high luminous efficiency. The electroluminescence performances of C6 and C9 modified phenanthroimidazoles as host emitters were evaluated as well as the dopant in the fabricated devices.

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Phenylamine phenanthroimidazole based bipolar compounds with donor-acceptor (D-A) architecture namely, 4-(1-(2,3-dihydrobenzo[][1,4]dioxin-5-yl)-6,9-di(pyren-4-yl)-1-phenanthro[9,10-]imidazol-2-yl)-,-diphenylaniline (DDPPPA) and 4'-(1-(2,3-dihydrobenzo[][1,4]dioxin-5-yl)-6,9-di(pyren-4-yl)-1-phenanthro[9,10-]imidazol-2-yl)-,-diphenyl-[1,1'-biphenyl]-4-amine (DDPBA) have been synthesized with highly fluorescent pyrene moieties at C6- and C9-positions. The C6 and C9 modification enhanced the thermal, photochemical and electroluminescent properties. Both molecules were employed as blue emitters in non doped organic light emitting devices (OLEDs) and show high performances due to hybridized local and charge-transfer properties.

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A new strategy developed to construct blue emissive materials having an unsymmetrical connection with identical conjugated phenanthrimidazole groups results in the separation of the frontier orbitals and leads to donor-acceptor (D-A) architecture. The blue device with 2-(naphthalen-1-yl)-1-(4-(1-(naphthalen-1-yl)-1-phenanthro[9,10-]imidazol-2-yl)phenyl)-1-phenanthro[9,10-]imidazole (-PPI)/2-(naphthalen-1-yl)-1-(3-(1-(naphthalen-1-yl)-1-phenanthro[9,10-]imidazol-2-yl)phenyl)-1-phenanthro[9,10-]imidazole (-PPI) emissive layer ( - 434/420 nm) shows high efficiencies: current efficiency ( ) - 5.83/3.

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