TECHNICAL FIELD

The present invention relates to a device containing an organometal-complex luminescent material, wherein the organometal-complex luminescent material serves as a dopant to play a photon emission role in a luminescent layer of the device.

BACKGROUND

The OLED (Organic Light-Emitting Diode) technology has been booming for 30 years since it was first published (organic electroluminescent diodes. Applied Physics Letters. 1987, Vol. 51, Iss. 12, Page 913) by Dr. Deng Qingyun of Kodak in 1987. In the past 5 years, the OLED technology has attracted a lot of attentions and investments from the industry due to its uniqueness. In the display field, compared with the current mainstream LCD (Liquid Crystal Display) technology, OLED display has great advantages of high brightness, high contrast, high resolution, ultra-thin display, and flexible display; in the lighting field, OLED lighting has great advantages such as high color rendering index (CRI), planar light source, and flexible light source. The OLED light-emitting technology currently faces the greatest disadvantages: high cost and short life.

An OLED device is composed of many functional layers. In a luminescent layer, a dopant that emits green light and red light has the best effect, and the most widely used is a phosphorescent material. There are currently two commonly used phosphorescent materials: an organometal-complex containing metal iridium (Ir), and an organometal-complex containing metal (Pt). Both red and green metal Ir complexes are of materials having very good properties.

Since the metal iridium has six coordination sites, the organometal-complexes containing Ir each have a stereoscopic structure of a regular octahedron. Most of organic compound ligands used to synthesize the Ir complexes have only two coordination sites, so one molecule needs to have three identical or different organic ligands. Most ligands have asymmetric structures, so when organometal-complexes of metal iridium (Ir) are synthesized, two configurations with the same molecular weight and completely different luminous properties are obtained, which are called a mer configuration and a fac configuration. Compared with the mer configuration, the fac configuration has higher luminous efficiency, but has higher cost for separating, especially in the industrial production process. In order to solve this problem, an auxiliary ligand (U.S. Pat. No. 6,830,828) can be introduced, and the conversion rate of molecules from the mer configuration to the fac configuration can also be improved by ultraviolet irradiation.

Metal platinum has four coordination sites, which can be formed into a unique configuration by designing tetradentate ligands, such that the formation of isomers can be completely avoided. Mark et al. used porphyrin as a ligand to form a Pt organometal-complex with a unique configuration (U.S. Pat. No. 6,303,238), but this complex had a poor luminous effect, and the quantum efficiency of a device was less than 1%. Chi et al. designed a series of tetradentate ligands with a Schiff base structure (US20050233167), of which the luminescence covers wavelength bands from green to red. However, the fluorescent quantum efficiency of red light molecules is still low (about 40%).

SUMMARY

In view of the defects in the above fields, the present invention provides a device containing an organometal-complex luminescent material. The novel organometal-complex luminescent material is a four-coordinated organometal-complex luminescent material, has a more rigid configuration and can thus be used to manufacture high-efficiency red OLEDs.

A light-emitting diode device containing the organometal-complex luminescent material comprises a luminescent layer which contains the organometal-complex having a structure as shown in formula I


wherein A, B and C refer to substituted or unsubstituted C, N, O and S atoms independently; a dashed ring for linkage between A and B atoms refers to a substituted or unsubstituted conjugated ring structure;

L1, L2, L3 and L4 are single bonds or double bonds independently, wherein L3 and L4 are part of the conjugated ring structure;

X, X1, Y and Y1 are C, N, O and S atoms independently;

Ar1 and Ar2 are a substituted or unsubstituted conjugated ring structure independently;

M refers to Pt, W and Au atoms;

the term “substituted” means being selected from, but not limited to: hydrogen, deuterium, sulfur, halogen, hydroxyl, acyl, alkoxyl, acyloxyl, amino, nitro, acylamino, cyano, carboxyl, styryl, aminocarbonyl, carbamoyl, benzylcarbonyl, aryloxyl, a saturated alkyl chain containing 1-30 C atoms, an unsaturated alkyl chain containing 1-30 C atoms, an aromatic ring containing 6-30 C atoms, and a heteroaromatic ring containing 6-30 C atoms.

The X and X1 are N atoms, the Y and Y1 are O atoms, and the M is a Pt atom.

The structure of the compound as shown in formula (I) may preferably be a structure of formula (II),



in which, m, n, and p are integers from 0 to 30; R1, R2, and R3are substituents other than hydrogen on the rings D, E, and F,

R1, R2, and R3are independently selected from deuterium, sulfur, halogen, hydroxyl, acyl, alkoxyl, acyloxyl, amino, nitro, acylamino, cyano, carboxyl, styryl, aminocarbonyl, carbamoyl, benzylcarbonyl, aryloxyl, saturated alkyl containing 1-30 C atoms, unsaturated alkyl containing 1-30 C atoms, an aromatic ring group containing 6-30 C atoms, and a heteroaromatic ring group containing 6-30 C atoms; adjacent R1, R2, and R3can be independently connected to one another through a covalent bond to form a ring; and

D and E are aromatic or heteroaryl rings each containing 6-30 C atoms; F is an aromatic or heteroaryl ring each containing 9-30 C atoms.

The D is a five- or six-membered aromatic ring or heterocyclic ring, a benzoaromatic ring or a benzohetercyclic ring; the E is a five- or six-membered heterocyclic ring or a benzohetercyclic ring; the F is a bi- or tri-cyclic aromatic ring, wherein R1, R2, R3are independently selected from halogen, a saturated alkyl chain containing 1-20 C atoms, an aromatic ring containing 6-20 C atoms, and a heteroaromatic ring containing 6-20 C atoms; adjacent R1, R2, and R3can be independently connected to one another through a covalent bond to form a ring; and m, n, and p are integers from 0 to 10.

The D is a benzene ring or a naphthalene ring, the E is a pyridine ring or a quinoline ring, and the F is a naphthalene ring or an anthracene ring, wherein R1, R2, R3are independently selected from halogen, a saturated alkyl chain containing 1-10 C atoms, an aromatic ring containing 6-10 C atoms, and a heteroaromatic ring containing 6-10 C atoms; adjacent R1, R2, and R3can be independently connected to one another through a covalent bond to form a ring; and m, n, and p are integers from 0 to 6.

The D is a benzene ring, the E is a pyridine ring, and the F is a naphthalene ring, wherein R1is hydrogen or halogen, wherein R2, R3are independently selected from halogen, a saturated alkyl chain containing 1-10 C atoms, and an aromatic ring containing 6-10 C atoms; and m, n, and p are integers from 0 to 3.

For the purposes of this application, unless otherwise specified, the terms halogen, alkyl, cycloalkyl, aryl, acyl, alkoxyl, and heterocyclic aromatic systems or heterocyclic aromatic groups may have the following meanings:

the aforementioned halogen or halide includes fluorine, chlorine, bromine and iodine, preferably F, Cl, Br, particularly preferably F or Cl, and most preferably F.

The above-mentioned conjugated ring structure, aryl, aryl moiety or aromatic system includes aryl that has 6-30 carbon atoms, preferably 6-20 carbon atoms, and more preferably 6-10 carbon atoms and is composed of one aromatic ring and a plurality of fused aromatic rings. Suitable aryl is, for example, phenyl, naphthyl, acenaphthenyl, acenaphthenyl, anthryl, fluorenyl, or phenalenyl. This aryl may be unsubstituted (i.e., all carbon atoms capable of being substituted carry a hydrogen atom) or substituted at one, more than one, or all substitutable positions of the aryl. Suitable substituents are, for example, halogen, preferably F, Br or Cl; alkyl, preferably alkyl having 1-20, 1-10 or 1-8 carbon atoms, particularly preferably methyl, ethyl, isopropyl or tert-butyl; aryl, preferably re-substituted or unsubstituted C6aryl or fluorenyl; heteroaryl, preferably heteroaryl containing at least one nitrogen atom, and particularly preferably pyridyl; and alkenyl, preferably alkenyl having a double bond, and particularly preferably alkenyl having a double bond and 1-8 carbon atoms. Aryl particularly preferably has substituents selected from F and tert-butyl, preferably given aryl or aryl which is C6aryl optionally substituted with at least one of the above-mentioned substituents, wherein the C6aryl particularly preferably has 0, 1 or 2 of the above substituents; the C6aryl is particularly preferably unsubstituted phenyl or substituted phenyl, such as biphenyl, or phenyl substituted with two t-butyl groups, preferably in a meta position.

The above-mentioned alkyl or alkyl moiety includes alkyl having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, and preferably 1 to 6 carbon atoms. The alkyl may be branched or linear, or may be cyclic, and may be interrupted by one or more heteroatoms, preferably N, O or S. Moreover, the alkyl may be substituted with one or more halogens or the above-mentioned substituents for the aryl. Similarly, in terms of alkyl, it is possible to carry one or more aryl groups. All the aforementioned aryl groups are suitable for this purpose. Alkyl is particularly preferably methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl, tert-butyl, sec-butyl, isopentyl, cyclopropyl, cyclopentyl, cyclohexyl.

The above-mentioned acyl is connected to a CO group with a single bond, such as the alkyl as used herein.

The alkoxyl is directly connected to oxygen with a single bond, such as the alkyl as used herein.

The above heteroaromatic system or heteroaromatic group is interpreted to be related to an aromatic, C3-C8cyclic group, and also contains one oxygen or sulfur atom or 1 to 4 nitrogen atoms or one oxygen or sulfur atom or a combination of at most two nitrogen atoms, and their substituted and benzopyrido-fused derivatives. For example, connected via one of ring-forming carbon atoms, the heteroaromatic system or heterocyclic aromatic group may be substituted with one or more of the mentioned substituents mentioned for the aryl.

In certain embodiments, the heteroaryl may be a five- or six-membered aromatic heterocyclic ring system carrying 0, 1 or 2 substituents. Typical examples of heteroaryl include, but are not limited to, unsubstituted furan, benzofuran, thiophene, benzothiophene, pyrrole, pyridine, indole, azole, benzoxazole, isoxazole, benzoisoazole, thiazole, benzothiazole, isothiazole, imidazole, benzimidazole, pyrazole, indazole, tetrazole, quinoline, isoquinoline, pyridazine, pyrimidine, purine and pyrazine, furan, 1,2,3-diazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, triazole, benzotriazole, pteridine, benzoxazole, diazole, benzopyrazole, quinazine, cinnoline, phthalazine, quinazole and quinoxaline and their mono- or di-substituted derivatives. In certain embodiments, the substituents are halo, hydroxyl, cyano, O—C1-6alkyl, C1-6alkyl, hydroxy C1-6alkyl, and amino-C1-6alkyl.

In order to achieve red light emission, an organometal-complex having a chemical structure of formula (II) needs a basic structure containing a Schiff base (that is, a structure formed by an N atom and an adjacent atom in the formula). It is mentioned in the background that the red light emission of Pt organometal-complexes having a Schiff base structure has the problem of low fluorescence quantum efficiency. In order to improve the fluorescence quantum efficiency of molecules, there are two main methods: 1. introducing strong σ-donor ligands; 2. enhancing the molecular stiffness and reducing the distortion in the configuration of the molecules in an excited state (Chi, Chem. sci., 2016, 7, 1653). Without changing the electronic structure of the molecules, the increase in a conjugate area of D, E, and F rings in formula II can effectively improve the stiffness of the molecules. The vibration of the molecules designed in this way in the excited state will be limited, and the modes of electronic transition will be reduced, which can directly improve the fluorescence quantum efficiency of the molecules.

On the premise of enhancing the fluorescence quantum efficiency of the core, the quenching of triplet excitons at high exciton concentrations can be suppressed by introducing anti-aggregation groups into the D, E, and F rings. In this way, it is possible to increase the doping concentration while ensuring that the current efficiency under high operating current does not change significantly, thereby further improving the working efficiency of a device.

Specific examples shown in formula (II) include, but are not limited to, the following structures:



An organic light-emitting device containing one or more luminescent materials is provided.

The luminescent material is applied to the light-emitting diode in a layer form in the device by means of thermal deposition, spin coating, or ink-jet printing.

The luminescent layer comprises a host material and a dopant, wherein the luminescent material is the dopant.

The host material is TCTA, and the dopant accounts for 1.5% of the total weight of the luminescent layer.

In the above organic light-emitting device, the device emits a monochromatic-red color when a current is applied to the layer.

An organometal complex in the luminescent material is high in fluorescence quantum efficiency and heat stability and low in quenching constant and can be used for manufacturing high-efficiency and low-efficiency roll-off red-light OLEDs.

