Red organic electroluminescent devices and its preparation method

Abstract

The invention belongs to a red organic electroluminescence device and a preparing method thereof. A vacuum evaporation technology is adopted to prepare indium tin oxide / 4, 4'-twin [N-(p-methylphenyl)-N-phenyl-amino] diphenyl or N, N'-double(1- naphthyl)-N, N'-biphenyl-1, 1'-biphenyl-4 and 4'-diamine / 8-hydroxyquinoline aluminum, classical trivalence europium composition Eu (TTA)3phen taking trifluoroacetylacetone thiofuran and BPT as a first ligand and a second ligand, and a main material 4, 4'-N, N'-twin carbazole biphenyl / 2, 9- dimethyl-4, 7- dimethyl-1, 10- phenanthroline / 8- hydroxyquinoline aluminum / lithium fluoride / aluminum. The ultimate electroluminescence current efficiency of the device is 6.1cd / A, the ultimatepower efficiency is 3.5lm / W, and the ultimate brightness is 2451.69cd / m<2>.

Description

technical field [0001] The invention relates to a red organic electroluminescent device and a preparation method thereof. Background technique [0002] 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. At present, the performance of green and blue organic electroluminescent devices has been significantly improved, and a small number of products have come out. However, as one of the three essential colors for organic e...

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Problems solved by technology

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 second Classical trivalent europium complex Eu(TTA) of primary and secondary ligands 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-o-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 current efficiency reached 4.7cd / A, its maximum brightness was only 800cd / m 2

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 current efficiency is as high as 4.14cd / A, but its maximum brightness is only 957cd / m 2

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 and brightness

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