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A novel dual core system was recently developed for producing highly efficient organic emitters. Triple-core chromophores were prepared by extending a dual core chromophore. 1,6-Di-anthracen-9-yl-pyrene (1,6 DAP core), 6,12-di-anthracen-9-yl-chrysene (DAC core), and 2,7-di-anthracen-9-yl-pyrene (2,7 DAP core) were designed and synthesized. Its physical and electroluminescent properties were also investigated. Triple-core chromophores were used for the blue fluorescent emitters. A structure of the device was fabricated as ITO/2-TNATA (60 nm)/ NPB (15 nm)/synthesized materials (35 nm)/Alq3(20 nm)/LiF (1 nm)/Al (200 nm). The device performance of 1,6 DAP core, DAC core, and 2,7 DAP core at 10 mA/cm2corresponded to luminance efficiencies of 4.97 cd/A, 3.95 cd/A, and 3.50 cd/A, respectively. [ABSTRACT FROM PUBLISHER]

Using 4,9-dibromopyrene as a key intermediate, two new fused-core compounds, TP-PFF and TP-PFC-TP, were synthesized. These compounds not only exhibited excellent thermal stability but also yielded superior electroluminescence (EL) devices with a lower turn-on voltage, over 50% greater efficiency, and over 3 times longer lifetime than did a similar compound lacking a fused core. This new core-forming method can be applied in various applications with many different core groups. [ABSTRACT FROM AUTHOR]

Three new emitting compounds of 5P-VCB, 5P-VAn and 5P-VPy for OLED based on hexaphenylbenzene moiety were synthesized. Physical properties by the change of the substitution groups of the synthesized materials were systematically examined. Photoluminescence spectrum of the synthesized materials showed maximum emitting wavelengths of about 420∼487 nm in solution state and 452∼488 nm in film state, indicating blue emission color. OLED devices were fabricated by the synthesized compounds using vacuum deposition process as an emitting layer. Current efficiencies and CIE values of 5P-VCB, 5P-VAn and 5P-VPy were 1.76, 0.38 and 7.91 cd/A and (0.15, 0.07), (0.20, 0.31) and (0.20, 0.36), respectively. [ABSTRACT FROM AUTHOR]

9,10-bis(3′′,5′′-diphenylbiphenyl-4′-yl)anthracene (TAT) and 4-(1′-(3′,5′-diphenylbiphenyl-4-yl)anthracen-9-yl)-N,N-diphenylaniline (TATa) which have electroluminescence (EL) maximum values of 441nm and 469 nm were used blue emitting materials in organic light emitting diodes (OLED). OLED devices were fabricated and characterized by co-deposited emitters of TAT and TATa with different ratios. C.I.E. values of the devices using TAT and TATa were changed from (0.148, 0.081) to (0.139, 0.194). [ABSTRACT FROM AUTHOR]

We report on phosphorescent homojunction organic light-emitting diodes (HJOLEDs) using p-i-n structures based on a single ambipolar organic semiconductor, 4,4′-Bis(carbazol-9-yl)-biphenyl, as matrix organic materials. In HJOLEDs, the phosphorescent dopant molecules play an important role in controlling the charge balance inside the emissive layer. We observe a four-fold enhancement in the luminous efficacy at 1000 cd/m2 from 3.7% to 12.9% by varying the emitter molecule. The influence of the energy level of the emitter molecule on charge balance is investigated by analyzing current density vs. voltage curves with the trap-limited current theory and by analyzing the electroluminescence spectra. [ABSTRACT FROM AUTHOR]

Using a 1-anthracen-9-yl-pyrene (AP) dual-core emitter, two new emitters of blue light, 1-spiro-9,9′-bifluoren-4-yl-6-(10-spiro-9,9′-bifluoren-4-yl-anthracen-9-yl)-pyrene (DSF-AP) and 1-[2-(9 H -carbazol-9-yl)phenyl]-6-[2-(9 H -carbazol-9-yl)phenyl-anthracen-9-yl]-pyrene (DCP-AP), were synthesized through boration and the Suzuki aryl-aryl coupling reaction. These two materials exhibited PL max values at 443 nm and 448 nm in a chloroform solution, and at 458 nm and 463 nm in a thin-film state. EL devices with the synthesized compounds were fabricated in the following configuration: ITO/4,4′,4″-tris( N -(2-naphthyl)- N -phenylamino)triphenylamine (2-TNATA) (60 nm)/ N , N ′-bis (naphthalene-1-yl)- N , N ′-bis(phenyl)benzidine (NPB) (15 nm)/synthesized blue light-emitting materials (35 nm)/Tris-(8-hydroxyquinoline)aluminum (Alq 3 ) (20 nm)/lithium fluoride (LiF) (1 nm)/Al (200 nm). Compared with the device made using an AP core lacking side groups, the device made with DCP-AP displayed 31% higher luminance efficiency (resulting in a value of 4.37 cd/A) and 32% higher power efficiency (to yield 1.93 lm/W), as well as a high external quantum efficiency (3.64%). [ABSTRACT FROM AUTHOR]