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Organic light-emitting devices

a light-emitting device and organic technology, applied in the direction of discharge tube luminescnet screen, other domestic articles, natural mineral layered products, etc., can solve the problems of low external efficiency of devices, optimization of stability and efficiency of oleds, etc., to achieve low turn-on voltage, high luminance, and high efficiency

Inactive Publication Date: 2005-11-03
THE UNIVERSITY OF HONG KONG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008] The main objective of this invention is to provide organic light-emitting devices (OLEDs) comprising an emissive layer, which employs at least one dopant complex as an electrophosphorescent emitter. The devices should exhibit low turn-on voltages, high luminance, high efficiencies, and desirable colors.

Problems solved by technology

Most of the organic small molecules exhibit fluorescence; hence, only 25% of the generated excitons are utilized resulting in the device with low external efficiency.
Even though remarkable progress has been made, challenges such as optimization of stability and efficiency of OLEDs need to be met before commercialization.

Method used

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Examples

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example 1

[0116] Example 1 shows the synthesis of dopant complex 1. The tetradentate NNNN-type ligand was prepared according to modification of literature procedures (see Bacchi et al., InorganicaChimica Acta. 342:229, (2003); Male et al., J. Chem. Soc., Dalton Trans. 2487, (1997)).

Synthesis of Dopant Complex 1

[0117] Sodium acetate (0.077 g, 0.94 mmol) was suspended in a DMF (10 mL) solution of bidentate ligand, N,N-Bis-( 1H-pyrrol-2-ylmethylene)-ethane-1,2-diamine (0.1 g, 0.47 mmol). K2PtCl4 (0.19 g, 0.47 mmol) dissolved in DMSO (1 mL) was dropwise added to the suspension at 80° C. dropwise. The resulting yellow solution turned orange-red after being stirred at 80° C. for 4 hours. After cooling, distilled water (50 mL) was then added to the orange-red mixture to afford an orange-brown precipitate. The solid product was filtered and washed with H2O (2×10 mL) to give an orange-brown solid, which was then purified by silica gel column chromatography with CH2Cl2 as the eluent. Removal of solve...

example 2

[0119] Example 2 shows the photophysical properties of non-limiting illustrative emissive materials corresponding to dopant complexes 1, 2 and 4 of the present invention. The absorption and photoluminescence properties of dopant complexes are provided in Table 3. UV / vis absorption, excitation and emission spectra of dopant complexes 1, 2 and 4 are shown in FIGS. 1 to 3 respectively. The photoluminescence (PL) spectrum is substantially independent of excitation wavelength from 300 to 450 nm. At room temperature, strong PL emissions are obtained with quantum yields (φ) up to 0.110 in CH3CN. The emission lifetimes of the dopant complexes range from 0.57 to 4.25 μs.

TABLE 3Physical characterization of dopant complexes 1, 2 and 4.Dopantλabs, sol. (nm)λem, sol.aτ (μs)bComplex[ε (10−4 dm3 mol−1cm−1)]a(nm)[Φem, sol.]1278 [1.52], 307 [1.47],566 (max),4.25 [0.097]317 [1.56], 372 [sh, 1.34],613388 [1.85], 438 [0.45],459 [sh, 0.36]2279 [1.45], 316 [1.64],563 (max),3.60 [0.110]367 [1.36], 383 [...

example 3

[0123] Example 3 illustrates a non-limiting method for preparing an OLED of the present invention. The electroluminescent devices were prepared on patterned indium-tin-oxide (ITO) glass with a sheet resistance of 20 Ω / square. The glass was cleaned sequentially in detergent solution, deionized water, ethanol and acetone. After the wet-cleaning process, the ITO glass was dried at 130° C. for 1 h and treated in UV ozone cleaner for 10 mins. In the practice of the present invention of this example, the device configuration is ITO / NPB (40 nm) / CBP:X wt. % dopant complex as illustrated in formulae (I), (II), (III) or (IV) (30 nm) / BCP (20 nm) / Alq3 (30 nm) / LiF (0.5 nm) / Al (150 nm); all of the layers were grown sequentially by thermal deposition at a deposition rate of about 0.2 Å / sec or about 5 Å / sec under a vacuum of 1×10−6 Torr.

[0124] The configuration of OLED in the present invention is schematically shown in FIG. 4. The device has multiple layers as shown. In particular, anode layer 410...

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Abstract

Disclosed are electrophosphorescent organic metal complexes with formula (I), (H), (III) or (IV), of either geometrical isomers, comprising two bidentate NN-type ligands, or two NO-type ligands, or a tetradentate NNNN-type ligand or a tetradentate NOON-type ligand, and a transition metal. These electrophosphorescent materials are valuable to the application in organic light-emitting devices (OLEDs), including red-, orange-, or yellow-light OLEDs.

Description

FIELD OF THE INVENTION [0001] The present invention relates to efficient organic light-emitting devices (OLEDs) which comprise a transition metal complex, wherein the transition metal complex, of either geometrical isomers, comprises two bidentate NN-type ligands, or two bidentate NO-type ligands, or a tetradentate NNNN-type ligand, or a tetradentate NOON-type ligand, and a transition metal atom as the electrophosphorescent emitter. The invention also relates to methods for preparing thin film OLEDs and their applications such as in liquid crystal displays, plasma panel displays and light-emitting diodes. BACKGROUND OF THE INVENTION [0002] Organic light-emitting devices (OLEDs) are finding applications as next-generation flat-panel displays (FPDs), liquid crystal displays (LCDs), and plasma display panels (PDPs). This has been driven by their favorable properties including lightweight, fast video response and low power consumption. To this end, organometallic compounds exhibiting el...

Claims

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Application Information

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IPC IPC(8): C09K11/06H01L51/00H01L51/50H05B33/14
CPCC09K11/06C09K2211/1007C09K2211/1011C09K2211/1044H05B33/14C09K2211/185H01L51/002H01L51/0087H01L51/5016C09K2211/1059Y10S428/917H10K71/30H10K85/346H10K50/11H10K2101/10
Inventor CHE, CHI-MINGCHAN, SIU-CHUNG
Owner THE UNIVERSITY OF HONG KONG
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