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Red organic electroluminescent device and method for fabricating the same

A technology of luminescence and devices, which is applied in the field of red organic electroluminescence devices and its preparation, can solve the problems of incomplete energy transfer of trivalent europium complexes, the maximum current efficiency is only 4.7, and only 1.4%. Luminescent efficiency, increase the probability of carrier recombination, and improve the effect of hole injection ability

Inactive Publication Date: 2008-04-09
CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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Problems solved by technology

However, as one of the three primary colors essential for organic electroluminescent displays, red organic electroluminescent devices still face severe challenges, mainly including low luminous efficiency and poor spectral color purity.
For example, in 2000, S.R.Forrest of Princeton University in the United States used 4,4'-N,N'-dicarbazole diphenyl (CBP) as the main material, and TTA and o-phenanthroline (phen) as the first The classic trivalent europium complex Eu(TTA) with the second ligand 3 When phen is doped in CBP as a guest material, a red electroluminescent device showing characteristic emission of pure trivalent europium ions is obtained, but the maximum external quantum efficiency of the device is only 1.4% (0.4mA / cm 2 ), far below the theoretical limit of 6% for the external quantum efficiency of the device
In 2003, Ma Dongge et al reported on Applied Physics Letters the rare earth europium complex Eu(TTA) with 3,4,7,8-tetramethyl-phenanthroline (Tmphen) as the second ligand 3 Tmphen, as a guest material, was mixed into the host material CBP to make a red organic electroluminescent device, although the maximum brightness reached 800cd / m 2 , but its maximum current efficiency is only 4.7cd / A
In 2005, Zhang Hongjie and others published in Inorganic Chemistry that 4,4,5,5,6,6,6-heptafluoro-1-(2-naphthyl)-n-ethane-β-diketone (HFNH) was the first Ligands of rare earth europium complexes Eu(HFNH) 3 phen, doped into CBP as a guest material to prepare a pure red electroluminescent device, the maximum brightness is as high as 957cd / m 2 , but its maximum current efficiency is only 4.14cd / A
On the other hand, most trivalent europium complexes only absorb light in the ultraviolet region, so it is easy to cause incomplete energy transfer from the host material to the trivalent europium complex, which is obviously not conducive to the improvement of device luminous efficiency

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  • Red organic electroluminescent device and method for fabricating the same
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  • Red organic electroluminescent device and method for fabricating the same

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Embodiment 1

[0038] Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer the ITO anode to the organic evaporation chamber after 10 minutes of low-pressure oxygen plasma treatment with a voltage of 250 volts under an atmosphere with a vacuum degree of 10 Pa. In a vacuum of 1-5 x 10 -5 In Pa's organic evaporation chamber, a 50-nanometer-thick TPD hole-transport layer, a 45-nanometer-thick Eu(TTA) 3 A phen-doped CBP emitting layer, a 20-nm thick BCP hole-blocking layer, and a 30-nm thick AlQ electron-transporting layer. Next, the unfinished devices are transferred to a metal evaporation chamber at 5-8 x 10 -5 A 1.2nm-thick LiF buffer layer was sequentially evaporated in a Pascal vacuum atmosphere, and finally a 80nm-t...

Embodiment 2

[0040] Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer it to the organic evaporation chamber after the ITO anode is treated with low-pressure oxygen plasma for 10 minutes with a voltage of 250 volts under the atmosphere of 10 Pa. In a vacuum of 1-5 x 10 -5 In Pa's organic evaporation chamber, a 50-nanometer-thick TPD hole-transport layer, a 45-nanometer-thick Eu(TTA) 3 A phen-doped CBP emitting layer, a 20-nm thick BCP hole-blocking layer, and a 30-nm thick AlQ electron-transporting layer. Next, the unfinished devices are transferred to a metal evaporation chamber at 5-8 x 10 -5 A 1.4nm-thick LiF buffer layer was sequentially evaporated in a Pascal vacuum atmosphere, and finally a 80nm-thick metal...

Embodiment 3

[0042] Firstly, the ITO anode layer on the ITO glass is chemically etched into strip electrodes with a width of 10 mm and a length of 30 mm, and then ultrasonically cleaned with cleaning solution and deionized water for 15 minutes and dried in an oven. Then put the dried substrate into the pretreatment vacuum chamber, and then transfer it to the organic evaporation chamber after the ITO anode is treated with low-pressure oxygen plasma for 5 minutes with a voltage of 250 volts under an atmosphere of 10 Pa. In a vacuum of 1-5 x 10 -5 In Pa's organic evaporation chamber, a 50-nanometer-thick TPD hole-transport layer, a 45-nanometer-thick Eu(TTA) 3 A phen-doped CBP emitting layer, a 20-nm thick BCP hole-blocking layer, and a 30-nm thick AlQ electron-transporting layer. Next, the unfinished devices are transferred to a metal evaporation chamber at 5-8 x 10 -5 A 1.2nm-thick LiF buffer layer was sequentially evaporated in a Pascal vacuum atmosphere, and finally a 80nm-thick metal A...

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Abstract

The invention relates to a red organic electroluminescence device and a fabrication method thereof. By using vacuum evaporation technique, a red organic electroluminescence device is fabricated, and the host materials are 4, 4'-N, N'-dicarbazole-diphenyl / 2, 9-dimethyl-4, 7-diphenyl-1, 10- phenanthroline / 8-hydroxyl quinoline / lithium fluoride (LiF) / aluminum (Al) with a configuration of indium tin oxide (ITO) / 4, 4'-di[N-(p-methylphenyl)-N-phenyl-amino]dimethyl / Eu(TTA)3phen, wherein Eu(TTA)3phen is the classical europium complex with trifluoroacetyl thiophene acetone (TTA) and o-phenanthroline (phen) as the first and the second ligands. The low-pressure oxygen plasma treatment on ITO anode is used to enhance hole injection, and the thickness of LiF and Al is precisely adjusted to suitably limit electron injection. The maximum electroluminescence current efficiency of the device is 9.53cd / A, the maximum power efficiency is 5.35lm / W, the maximum external quantum efficiency is 5.15 percent, and the corresponding maximum recombination rate of the device is 85.8 percent.

Description

technical field [0001] The invention relates to a red organic electroluminescent device and a preparation method thereof. Background technique [0002] Organic electroluminescent display is a new type of display technology that is gradually becoming mature in the field of optoelectronic devices and has great practical prospects. Compared with other flat display technologies such as liquid crystal displays, plasma display devices, and field emission displays, organic electroluminescent displays have a series of excellent characteristics, such as: adjustable luminous color, active luminescence, high brightness, high efficiency, wide viewing angle, Low energy consumption, simple preparation process, and the ability to prepare curved and flexible display screens have broad application prospects in the field of large flat-panel full-color displays, and are generally considered to be the most competitive next-generation display technology. Therefore, the research on organic elect...

Claims

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Application Information

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IPC IPC(8): H01L51/50H01L51/54H01L51/56
Inventor 张洪杰周亮邓瑞平
Owner CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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