Efficient fluorescent OLEDS based on assistant acceptor modulated HLCT emissive state for enhancing singlet exciton utilization.

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.

Efficient donor-acceptor emitter based nonsymmetrical connection for organic emitting diodes with improving exciton utilization.

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.