Position Effect Based on Anthracene Core for OLED Emitters.

Green-orange emitters based on anthracene core have been successfully synthesized by substitution with triphenylamine side group in the 9, 10 or 2, 6 positions. There are larger blue shifts in the UV-visible absorption and PL spectra of the synthesized 2,6-substituted derivative compared to the 9,10-substituted derivative. When the synthesized compounds were used as emitting layers in non-doped OLED devices, a related trend was observed in their optical properties. In particular, the OLED device containing the 2,6-substituted derivative was found to exhibit excellent characteristics, with maximum EL emission at 518 nm, pure green emission with CIE coordinates of (0.334, 0.604), and external quantum efficiency of 2.83%.

Synthesis and Luminescent Properties of Poly(9-(3-vinyl-phenyl)-phenanthrene).

Recently, interest of polymer light-emitting diode (PLED) fabricated from conjugated polymer has augmented because PLED has advantage property that is well-suited to flexible lighting and solution processed device. In this presentation, we suggest a new polymer host based on phenanthrene, poly(9-(3-Vinyl-phenyl)-phenanthrene) (PVPP). It can be easily synthesized through simple synthetic methods which are Suzuki and Wittig reactions. PVPP film can be obtained from spin coating with solution used by common solvent. It exhibited PL maximum value of 381 nm and broad PL spectrum. Energy transfer smoothly occurred when the three dopants for green, red and yellow were used in PVPP.

Solution Processable White Organic Light-Emitting Diodes Using New Blue Host Material Including Substituent Group.

New host material of T-TATa isomer substituted t-butyl group was investigated in solution process WOLED device compared with 4-(10-(3',5'-diphenylbiphenyl-4-yl)anthracen-9-yl)-N,N-diphenylaniline [TATa]. A two-color WOLED of a co-host system using solution process method was demonstrated. The device configuration was ITO/PEDOT:PSS (40 nm)/emitting layer (50 nm)/TPBi (20 nm)/LiF (1 nm)/AI. The emitting layer consisted of TATa or T-TATa isomer, NPB, DPAVBi (blue dopant), and rubrene (yellow dopant). NPB was used as not only blue host but also helping hole carrier transport. The device using T-TATa compound as a co-host exhibited a luminance efficiency of 3.39 cd/A, which is about twice higher than TATa device of 1.58 cd/A at 10 mA/cm2.

Synthesis and Luminescent Property of Poly(9-(3-vinyl-phenyl)-anthracene).

Polymer light-emitting diodes (PLEDs) have attracted much attention from academia and industry field because of their various applications such as large area flat-panel displays and lightings. In this paper, we suggest new blue emitting polymer based on anthracene, Poly(9-(3-Vinyl-phenyl)-anthracene) (PVPA). From NMR data, vinyl group protons were disappeared and aromatic protons showed broad proton peaks because of polymer characteristics. PVPA had film property well and it exhibited vivid PL maximum values of 431, 455, 482 nm and broad PL spectrum. Three dopants for green, red, yellow were used to PVPA, all energy transfer was happened well. By using rubrene dopant of yellow emission, doped film provided white PL.

Synthesis and Electroluminescence Property of New Hexaphenyl Benzene Derivatives Including Emitting Core for OLED.

Three new emitting compounds of 5P-2TPA, 5P-2An and 5P-2Py for OLED based on hexaphenyl benzene moiety were synthesized. Physical properties were systematically examined by the change of the substitution groups of the synthesized materials. Photoluminescence (PL) spectrum of the synthesized materials showed maximum emitting wavelengths of about 437~488 nm in solution state and 457~516 nm in film state, indicating blue emission color. OLED devices were fabricated by the synthesized compounds using vacuum deposition process as an emitting layer. Device structure was ITO/2-TNATA 60 nm/NPB 15 nm/EML 35 nm/TPBi 20 nm/LiF 1 nm/Al 200 nm. External quantum efficiencies and CIE values of 5P-2TPA, 5P-2An and 5P-2Py were 3.34, 1.06 and 2.06% and (0.14, 0.12), (0.23, 0.45) and (0.24, 0.45), respectively. The three compounds exhibited thermal stablility with high Td of 426 °C, 449 °C and 467 °C.

A new approach way for white organic light-emitting diodes based on single emitting layer and large stokes shift.

New red dopant, DPPZ based on porphyrin moiety was synthesized. DPPZ showed UV-Vis and PL maximum values of 412 and 638 nm, indicating the large stokes shift. New blue host compound, TATa was also synthesized and used for co-mixed white emission. TATa exhibited UV-Vis. and PL maximum values of 403 nm and 463 nm in film state. Thus, when two compounds are used as co-mixed emitter in OLED device, there is no energy transfer from blue emission of TATa to DPPZ due to large stokes shift of DPPZ. Based on the PL result, it is available to realize two-colored white in PL and EL spectra. As a result of this, two-mixed compounds showed vivid their own PL emission peaks of 466 and 638 nm in film state. Also, white OLED device using two-mixed compounds system was fabricated. EL spectrum shows 481 and 646 nm peaks and two separate EL peaks. As the operation voltage is increased from 8 to 11 V, EL spectrum does not change the peak shape and maximum wavelength values. EL performance of white device showed 0.041 cd/A, 0.018 Im/W, and CIE (0.457, 0.331) at 8 V.

New hole transporting materials based on hexaarylbenzene and aromatic amine moiety for organic light-emitting diodes.

Three different new hole transport compounds, namely DPAP-TB, 1-PNAP-TB and 2-PNAP-TB, were synthesized by Sonogashira coupling and Diels-Alder reaction. Synthesized materials exhibited high Tg in the range of 118 to 133 °C. These values are higher than that of NPB, which is commonly used as a hole transporting material. OLED devices were fabricated by the synthesized compounds using the solution process as a hole transporting layer. Device structure was ITO/PEDOT:PSS (40 nm)/synthesized compounds or NPB (20 nm)/Alq3 (70 nm)/LiF/Al. Luminance efficiencies and external quantum efficiencies of DPAP-TB, 1-PNAP-TB and 2-PNAP-TB devices were 3.98, 4.62, 4.22 cd/A, and 1.35, 1.56, 1.43% at 20 mA/cm2, respectively. In luminance efficiency and external quantum efficiency, 1-PNAP-TB especially had superior property to NPB.

Synthesis and electroluminescence property of new hexaphenylbenzene derivatives including amine group for blue emitters.

Three new blue-emitting compounds of 5P-VA, 5P-VTPA, and 5P-DVTPA for organic light-emitting diode (OLED) based on hexaphenylbenzene moiety were demonstrated. 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 400 to 447 nm in solution state and 451 to 461 nm in film state, indicating deep blue emission color. OLED devices were fabricated by the synthesized compounds using vacuum deposit process as an emitting layer. The device structure was ITO/2-TNATA 60 nm/ NPB 15 nm/ EML 35 nm/ TPBi 20 nm/ LiF 1 nm/ Al 200 nm. External quantum efficiencies and CIE values of 5P-VA, 5P-VTPA, and 5P-DVTPA were 1.89%, 3.59%, 3.34%, and (0.154, 0.196), (0.150, 0.076), (0.148, 0.120), respectively. 5P-VTPA and 5P-DVTPA exhibited superior highly blue quality and thermal property such as high Td of 448°C and 449°C.

Synthesis and characterization of titanium complex with a dithiolate ligand for green LCD color filter dyes.

Three green compounds for color filter dyes based on bis(cyclopentadienyl) titanium complexes including dithiolate ligand were synthesized. Physical properties by the change of the substitution groups of the synthesized materials were systematically examined. UV-visible absorption spectrum of the synthesized materials showed maximum absorbing wavelengths of 427 to 430 nm and 632 to 635 nm in solution state, and 434 to 438 nm and 637 to 651 nm in film state, indicating green and black colors. It was observed that the extinction coefficient values (log ε) of all the synthesized materials are very high at 4.0 or above. In addition, it was shown that since the Td values of three synthesized materials show thermal stability higher than 240°C, they possess high potential to be applied as dyes for LCD color filter and black matrix addictive.

A study on single-layered white organic light-emitting diodes based on Co-host system using solution process.

Two color white organic light-emitting diode (WOLED) that used a co-host system in a solution process method was prepared. A device configuration is ITO/PEDOT:PSS (40 nm)/emitting layer (50 nm)/TPBi (20 nm)/LiF (1 nm)/Al. The emitting layer consists of TATa+ alpha-NPB or beta-NPB + DPAVBi (blue dopant) + Rubrene (yellow dopant). The device using alpha-NPB or beta-NPB showed white color of CIE (0.30, 0.40) and (0.29, 0.39), respectively. Device efficiency of alpha-NPB was 3.85 cd/A at 100 mA/cm2, which is about 15% higher than beta-NPB's.