A deep red organic light-emitting metal-iridium complex and its application in organic electroluminescent devices

Abstract

Quinoline or isoquinoline is used with fused aromatic heterocycles to form an organic luminescent ligand, and alkyl-fluoroalkyl mixed substituted phenylpyridine is used as an auxiliary ligand to obtain a deep red organic luminescent metal iridium complex, which has the advantages of lowering the sublimation temperature, increasing the solubility and improving the performance of thermally stable materials. The solution-forming organic luminescent layer is obtained by combining a cross-linkable group and can be further cross-linked into an insoluble and infusible network structure. The applied OLED light-emitting diode has improved efficiency and long life.

Description

Technical Field

[0001] The present invention relates to a deep red organic light-emitting metal iridium complex and an organic electroluminescent device prepared therefrom, which can be applied to organic light-emitting OLED devices, improve the solubility and sublimation evaporation processability of the light-emitting material, and facilitate the large-scale production of OLED light-emitting devices and display devices with improved performance. Background Art

[0002] Organic semiconductor materials are new optoelectronic materials. Their large-scale research originated in 1977 when Hideki Shirakawa, A. Heeger and A. McDiamid jointly discovered doped polyacetylene with conductivity up to the copper level. Subsequently, in 1987, C. Tang et al. of Kodak invented organic small molecule light-emitting diodes (OLEDs), and in 1990, R. Friend and A. Holmes of Cambridge University invented polymer light-emitting diodes P-OLEDs, and in 1998, S. Forrest and M. Thomson invented more efficient organic phosphorescent light-emitting diodes PHOLEDs. Due to the advantages of easy structural adjustment, diverse varieties, adjustable energy bands, and even low cost like plastic film processing, and the numerous applications of organic semiconductors in conductive films, electrostatic copying, photovoltaic solar cell applications, organic thin film transistor logic circuits, and organic light-emitting OLED flat panel displays and lighting, the three scientists Shirakawa-Heeger-McDiamid won the Nobel Prize in Chemistry in 2000.

[0003] As the next generation of organic electroluminescent diodes for flat panel display applications, organic optoelectronic semiconductor materials require: 1. High luminous efficiency; 2. Excellent electron and hole stability; 3. Appropriate luminescent color and rich color scale; 4. Excellent film processing. In principle, most conjugated organic molecules (including star emitters), conjugated polymers, and organic heavy metal complexes containing conjugated chromophore ligands have electroluminescent properties and are used in various types of light-emitting diodes, such as organic small molecule light-emitting diodes (OLEDs), polymer organic light-emitting diodes (POLEDs), and organic phosphorescent light-emitting diodes (PHOLEDs). Phosphorescent PHOLEDs use both singlet excited state (fluorescence) and triplet excited state (phosphorescence) luminescence mechanisms, and obviously have much higher luminous efficiency than small molecule OLEDs and polymer POLEDs. PHOLED manufacturing technology and excellent PHOLED materials are essential for achieving low-power OLED display and lighting. The quantum efficiency and luminous efficiency of PHOLEDs are 3 to 4 times that of fluorescent OLED materials, which also reduces the heat generated and increases the competitiveness of OLED display panels. This provides the possibility that OLED display or lighting can surpass LCD display and traditional light sources in general. Therefore, existing high-end OLED devices are more or less doped with phosphorescent OLED materials.

[0004] Phosphorescent OLED materials are composed of organic luminophores with certain conjugation as bidentate chelating ligands, which form cyclometal-ligand complexes with metal elements such as iridium and platinum. Under high-energy light (such as ultraviolet light excitation) or charge injection (electrical excitation), they become excitons due to cyclometal-ligand charge transfer (MLCT), and then return to the ground state to cause luminescence. In OLED devices, charge injection is through the injection of holes from the anode after applying a positive voltage to the anode, and the injection of electrons after applying a negative voltage to the cathode. They pass through the electron transport layer and the hole transfer layer respectively, and enter the body or main material of the emission layer at the same time. The electrons eventually enter the lowest unoccupied molecular orbital (LUMO) of the luminescent dopant, and the holes enter the highest occupied molecular orbital (HOMO) of the luminescent dopant to form excited state luminescent dopant molecules (exciton state). After the exciton state returns to the ground state, it is accompanied by the emission of light energy, and the wavelength of the emitted light energy corresponds to the energy gap (HOMO-LUMO energy level difference) of the luminescent molecule dopant.

[0005] There have been many reports of precious metal organic ligand complexes. Under the influence of precious metals, the spin-orbit effect is enhanced, making the originally weak phosphorescence become very strong and showing excellent phosphorescence emission, and obtaining electroluminescent devices with an internal quantum efficiency close to 100%. For example, the green-emitting tris(phenylpyridine)iridium(III) complex, referred to as Ir(PPY)3, has the structural formula:

[0006]

[0007] FirPic, which emits blue light, has the following structural formula:

[0008]

[0009] The main ligand 4,6-difluorophenylpyridine dominates the emission color.

[0010] The tri(octylquinoline)iridium(III) complex emitting red light has excellent high-efficiency emission performance (Adv.Mater.19,739(2007)). Its structural formula is:

[0011]

[0012] There are many types of triplet phosphorescent materials used in organic light-emitting devices (OLEDs). Table 1 lists the corresponding literature.

[0013] Table 1: Various organic OLED semiconductor light-emitting materials that have been reported:

[0014]

[0015]

[0016]

[0017]

[0018]

[0019] However, due to the large molecular weight of the metal iridium tri-ligand complex itself and the strong intermolecular force of the conjugated luminescent ligand used, most organic metal iridium complexes have problems that affect the large-scale production of OLEDs, such as sublimation and evaporation temperatures close to the decomposition temperature of the complex, and difficulty in solubility and purification. In order to meet the ever-increasing requirements of industrial production and obtain efficient and long-life organic OLED display and lighting products, it is imperative to develop better, more efficient and easy-to-manufacture luminescent materials. In addition, one of the future development trends is to use organic metal luminescent materials with good solubility to obtain solution methods to manufacture OLED organic light-emitting device display screens or lighting OLED devices through inkjet printing or other solution processing processes. The solution is required to form a film and become an infusible and insoluble luminescent layer through chemical cross-linking, which is conducive to the lamination of multi-layer structure OLED light-emitting devices using a full solution processing method.

[0020] One way to design the molecule of organic metal iridium complex phosphorescent material is to form a homoleptic complex with Ir by a chelating ligand containing N atoms. Another way is to use one or two chelating auxiliary ligands containing nitrogen atoms or oxygen atoms with shorter emission wavelengths, and two or one chelating main ligands containing N atoms with longer emission wavelengths to form hybrid or heteroleptic dopants complex luminescent compounds with precious metal iridium. Due to the natural transfer effect of emission wavelength from high energy (or short wavelength) to low energy (or long wavelength), under the conditions of light excitation or electrical excitation, the hybrid or heteroleptic metal complex material eventually shows the main ligand emission wavelength. Therefore, in a heteroleptic iridium complex, the ligand with lower energy and longer emission wavelength is the main ligand that determines the final color, while the non-coloring ligand is the auxiliary ligand. Here, the auxiliary ligand is usually of small molecular weight, which is conducive to the final molecular dissolution or sublimation purification, or is conducive to solution film formation and thermal vacuum sublimation coating processing. Based on this principle, in recent years, there have been many reports on the use of hybrid complexes to reduce the sublimation temperature and expand the vapor deposition processability. For example, patent applications US20100244004 and CN102439019A reported the use of 6-methyl-2-phenylpyridine as a heteroligand. By reducing the molecular weight, the homoligand that is difficult to sublime is improved according to the complex luminescent compound (A). The obtained heteroligand has an unchanged luminescent wavelength according to the complex luminescent compound (B), but can sublime at a lower sublimation temperature.

[0021]

[0022] (A): Homoligand-based complex luminescent compound: difficult to sublime (B): Heteroligand-based complex luminescent compound: sublimable

[0023] Although the above-mentioned reduction in molecular weight or use of a chelating auxiliary ligand with a smaller conjugated chromophore can reduce the sublimation temperature, it often still cannot meet the increasing requirements for OLED preparation.

[0024] It has been reported that the electron-withdrawing property of trifluoromethyl bonded to the pyridine ring can bring about red shift of the luminescent compound to obtain deep red luminescence (US2015 / 0053937, JH. Kim, et al; CN103694277, Li Xiaochang, etc.). The electron-withdrawing fluoro or trifluoromethyl bonded to the phenyl bonded to the pyridine ring can bring about blue shift of the luminescent iridium complex to obtain a deeper blue light material (JP2013-197323, EP1191611A2. US2014 / 0367647A1, CN104004026). However, directly bonding halogen, fluorine or fluoroalkane to the luminescent ligand will not only passivate the ligand to reduce the further reaction activity and yield of the complex formation, but also lead to the deterioration of the luminescent performance of the luminescent complex. As a deep red light organic metal complex, it usually refers to a luminescent dopant with an electroluminescent wavelength greater than 618nm and CIEy>0.67. The U.S. patent application US.App.20170352821 uses partially fluorinated long-chain branched ligands and acetylacetone derivatives as auxiliary ligands to obtain a deep red organic light-emitting complex. Although the acetylacetone derivatives as auxiliary ligands can give the complex an additional red shift, they will lead to a decrease in the decomposition temperature of the complex and are not conducive to the industrial thermal evaporation preparation of OLED displays. Summary of the invention

[0025] The present invention is aimed at the above-mentioned deficiencies of the prior art. Considering that most of the current deep red organic metal luminescent complexes are complexes constructed using acetylacetone or its derivatives, and such complexes generally have the disadvantage of poor thermal stability, the present invention discloses a method of using phenylpyridine or its derivatives as an auxiliary ligand of a red light emitting material. The auxiliary ligand phenylpyridine has better heat resistance and more stable bonding strength than acetylacetone or its derivatives. In addition, in order to obtain the deep red luminescent characteristics required by OLED display, a fused aromatic heterocycle is used to impart a more developed hole injection ability (dominant HOMO), and is combined with quinoline or isoquinoline that dominates LUMO as a deep red luminescent ligand to obtain a new organic luminescent material. The characteristics of the present invention also involve the use of partially fluorinated alkyl-substituted phenylpyridine as an auxiliary ligand to develop a class of organic red metal iridium complexes with solubilization and self-lubricating effects, which can not only increase the solubility of the entire heteroleptic iridium metal complex, but also facilitate solution purification or solution coating processing, and at the same time can significantly reduce the sublimation temperature of heteroleptic iridium complexes of the same size or even increased molecular weight. By using phenylpyridine as an auxiliary ligand, using alkyl-fluoroalkyl mixed substitution for the phenylpyridine auxiliary ligand, and using a condensed aromatic heterocycle dominating the HOMO to bond with quinoline or isoquinoline to form the main ligand, the new red light-emitting organometallic iridium complex obtained combines the effects of easy solubility, easy sublimation, higher heat resistance and increased device aging life performance.

[0026] In order to solve the above technical problems and achieve the above material and device effects, the technical solution adopted by the present invention is to disclose a luminescent metal iridium complex, characterized in that the structure of the complex is shown in the following general formulas (1) and (2):

[0027]

[0028] Wherein phenylpyridine is an auxiliary ligand, and in the auxiliary ligand, h=1-4, k=0-2, and m=1-12 in the mixed alkyl-fluoroalkyl group;

[0029] In the auxiliary ligand, Y is H, D, an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a fluorinated alkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a pyridyl group, a substituted pyridyl group, a carbazolyl group, a benzofuranyl group, a benzothienyl group, a condensed aromatic heterocycle having less than 12 carbon atoms, F, Cl, NO2, one or more chemical crosslinking groups, or a secondary amine -N(RR)2 bonded to a nitrogen atom, a secondary amine wherein R is an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a benzofuranyl group, a benzothienyl group, or a carbazolyl group;

[0030] q, m, and n are the number of substituents on the aromatic heterocyclic ring, which can be 1-4;

[0031] Ar in the ligand is the following fused ring:

[0032]

[0033]

[0034] In the ligand, R1, R2, R3, and R4 are H, D, an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a fluorinated alkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a pyridyl group, a substituted pyridyl group, a carbazolyl group, a benzofuranyl group, a benzothienyl group, a condensed aromatic heterocycle having less than 12 carbon atoms, F, Cl, Br, or a secondary amine -N(RR)2 bonded to a nitrogen atom, wherein R in the secondary amine is an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a benzofuranyl group, a benzothienyl group, or a carbazolyl group.

[0035] In the general formula (1), h in the mixed alkyl-fluoroalkyl group is 1-4, so as to avoid the carbon atom connected to fluorine being directly connected to the pyridine ring to affect the photoelectric properties of the auxiliary ligand or its complex forming activity.

[0036] According to the scope of this patent, the luminescent ligand formed by the Ar fused ring and isoquinoline or quinoline described herein has a better conjugated system than the luminescent ligand formed by the general phenyl-isoquinoline or phenyl-quinoline derivatives, thereby leading to a smaller energy gap of its organic metal iridium complex, or a deeper red luminescent effect. Full-color OLED display screens are increasingly in need of organic luminescent materials with full red, green and deep blue light, where the red light emission wavelength exceeds 620nm to ensure that CIEx is equal to or greater than 0.68. The use of phenyl-pyridine as an auxiliary ligand has better heat resistance than the use of acetylacetone or its derivatives, which is manifested in the increase of the thermal decomposition weight loss temperature and the expansion of the industrial evaporation and sublimation operation window.

[0037] However, only using a more developed conjugated Ar fused ring to form a luminescent ligand with isoquinoline or quinoline, and using a more heat-resistant phenyl-pyridine or its derivatives often leads to an increase in the molecular weight of the luminescent complex and brings about the problem of sublimation difficulties. The present invention introduces an alkyl-fluorocarbon mixture into the phenylpyridine auxiliary ligand, and the fluorinated carbon alkyl metal complex thus formed has the excellent properties of the original luminescent iridium complex Ir(L)3, and the partially fluorinated alkyl group brings self-lubricating effect to the luminescent molecule, which greatly improves the purification difficulties caused by the poor solubility of the original luminescent iridium complex Ir(L)3, effectively reduces the sublimation or vacuum thermal evaporation temperature, saves heat energy consumption, and reduces the possibility of thermal decomposition of organic light-emitting materials during the evaporation process. Document US patent application US.Pat.Appl.20200017536 discloses the use of alkyl-substituted pyridine combined with fused ring naphthalene to obtain a yellow metal iridium organic complex luminescent material with improved OLED device life, but takes into account the problem of increased sublimation temperature and uses acetylacetone as an auxiliary ligand. However, due to the small O-Ir bonding energy in the auxiliary ligand of acetylacetone or its derivatives, the thermal decomposition temperature of the complex is insufficiently reduced. According to the scope of this patent, the use of phenyl-pyridine as an auxiliary ligand has better heat resistance than the use of acetylacetone or its derivatives, which is manifested in the increase of the thermal decomposition weight loss temperature, thereby expanding the operating range of industrial evaporation material films and industrial sublimation purification temperatures.

[0038] The organic luminescent iridium complex provided by the present invention is a mixture of polyfluorocarbons introduced into phenylpyridine as an auxiliary ligand. The fluorinated carbon alkyl metal complex formed thereby greatly improves the purification difficulty caused by the poor solubility of the original luminescent iridium complex Ir(L)3, effectively reduces the sublimation or vacuum thermal evaporation temperature, saves thermal energy consumption, and reduces the possibility of thermal decomposition of organic luminescent materials during the evaporation process. The general formula of polyfluorocarbons herein is: -(CH2) h CH k [C m F (2m+1) ] 3-k, where h = 1-4; k = 0-2, m = 1-12, that is to say, polyfluorocarbons are different from halogen substitutions and F substitutions, and are also different from -CF3 substitutions, but are alkyl-fluorocarbon mixtures, in which the bonding with the auxiliary ligand phenylpyridine or the main ligand is through a normal alkyl group, ensuring that the photoelectric properties and complex formation ability of the organometallic complex are not subject to fluorine passivation or halogen passivation.

[0039] The polyfluorocarbon herein may also be a partially deuterated or fully deuterated alkyl-fluorocarbon mixture; in the case of partially deuterated alkyl-fluoroalkyl, the general formula used is: -(CD2) h CH k [C m F (2m+1) ] 3-k , wherein h = 1 to 4; k = 0 to 2, m = 1 to 12; when all deuterated alkyl-fluoroalkyl groups are used, the general formula is: -(CD2) h CD k [C m F (2m+1) ] 3-k , where h = 1 to 4; k = 0 to 2, m = 1 to 12. Partial or full deuteration brings about easy identification and detection of isotopes and is widely used in probes or unique light-emitting devices. In addition, partial or full deuteration also slightly improves the stability of the light-emitting material and the application life of the OLED device. The excellent hydrophobicity brought by the fluorinated carbon chain and the organic light-emitting complex described in the present invention are used in OLED light-emitting devices, which also shows an extension of the device's working life. After using a partially deuterated alkyl-fluorocarbon mixture, the general formula is as follows:

[0040]

[0041] The life of OLED devices is often reduced due to the penetration of water and oxygen from the weak parts of the device packaging. The wonderful effect of the present invention is that due to the excellent hydrophobicity or water molecule adsorption repelling effect brought by the fluorine-containing carbon chain, the organic light-emitting complex of the present invention is used in OLED light-emitting devices, especially showing the effect of extending the working life of the device.

[0042] In the scope of the present invention, the fluorine-containing auxiliary heteroligand can, in principle, be hybridized with various combinations of luminescent main ligands and metal iridium to form a series of novel luminescent metal complexes, wherein the heteroleptic iridium metal complexes formed by isoquinoline and fused aromatic heterocycles include but are not limited to the following complexes (Table 2):

[0043]

[0044]

[0045] In the scope of the present invention, the fluorine-containing auxiliary heteroligand can be hybridized with various combinations of luminescent main ligands and metal iridium to form a series of novel luminescent metal complexes, wherein the heteroleptic iridium metal complexes formed by quinoline and fused aromatic heterocycles include but are not limited to the following complexes (Table 3):

[0046]

[0047]

[0048] The use of fluorocarbon chain substitution on the auxiliary ligand brings better solubility, making it easier for this type of organic light-emitting complex to implement solution film formation, such as inkjet printing, blade coating, spin coating, etc. to form a light-emitting layer. In order to facilitate the preparation of multi-layer OLEDs, after the soluble light-emitting complex is formed into a film using a solution, the present invention also provides a function that can be further chemically cross-linked to become insoluble and infusible. The method is that Y in the heteroleptic iridium metal complex contains at least one chemical cross-linking group. In principle, a variety of chemical cross-linking groups can be selected, and there are many chemically cross-linkable groups in the literature, among which the cross-linking groups suitable for the present invention are selected from vinyl, acrylate or trifluorovinyl. These cross-linking groups will undergo intermolecular cross-linking to form a network structure when heated to 160°C, becoming insoluble and infusible macromolecules. On the other hand, these cross-linking groups can also promote chemical cross-linking under sufficiently strong ultraviolet light.

[0049] In the scope of the present invention, the organic metal luminescent complex with acrylate crosslinkable includes the following general structure:

[0050] Under heating or strong ultraviolet light, the following cross-linking reaction occurs, (3) forming an insoluble and infusible macromolecular network:

[0051]

[0052] In the scope of the present invention, the crosslinkable organic metal luminescent complex with styrene includes the following general structural formula (4):

[0053]

[0054] The following cross-linking reaction occurs under heating or strong ultraviolet light to form an insoluble and infusible macromolecular network:

[0055]

[0056] In the scope of the present invention, the crosslinkable organic metal luminescent complex with trifluoroethylene includes the following general structure:

[0057]

[0058] Under heating or strong ultraviolet light, the following cross-linking reaction occurs, (5) forming an insoluble and infusible macromolecular network:

[0059]

[0060] According to the general formulas (3), (4) and (5) of the cross-linkable organic metal luminescent complex, in principle, there are many compounds that can achieve a red light emitting complex, wherein typical compounds include but are not limited to the following red light emitting cross-linkable compounds:

[0061]

[0062]

[0063] In order to obtain the fluorine-containing auxiliary heteroligand and its organic metal complex, a variety of chemical preparation methods, such as Suzuki reaction, Grignard reaction or ring-closing reaction, or other known synthesis routes can be used. Specifically, a synthesis route is as follows: Reaction formula I is to obtain the fluorine-containing auxiliary ligand 2 by reacting bromide with butyl lithium; the auxiliary ligand 2 and IrCl3 or its hydrate form the auxiliary ligand-Ir chlorobridge compound 3; the chlorobridge compound and silver salt, such as silver trifluorosulfonate, form a more active preparative 5; the preparatory complex 5 and the bidentate chelated luminescent ligand L containing N atoms form the final hetero-organic metal iridium luminescent complex 7 (final total yield 45-60%).

[0064]

[0065] Reaction Test I: Preparation of Organometallic Iridium Complex with Double Auxiliary Ligands

[0066] Similarly, a metal iridium complex containing one auxiliary ligand and two luminescent main ligands can be obtained using a similar reaction (yield 60-80%).

[0067]

[0068] Reaction II: Preparation of single auxiliary ligand organometallic iridium complex

[0069] Wherein R is a mixed alkyl-fluoroalkyl group in the phenylpyridine auxiliary ligand, which can be of the general formula -(CH2) h [C m F (2m+1) ] 3-k , where h = 1-4; k = 0-2, m = 1-12;

[0070] In the auxiliary ligand, Y is H, D, an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a fluorinated alkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a pyridyl group, a substituted pyridyl group, a carbazolyl group, a benzofuranyl group, a benzothienyl group, a condensed aromatic heterocycle having less than 12 carbon atoms, F, Cl, NO2, one or more chemical crosslinking groups, or a secondary amine -N(RR)2 bonded to a nitrogen atom, a secondary amine wherein R is an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a benzofuranyl group, a benzothienyl group, or a carbazolyl group;

[0071] q, m, and n are the number of substituents on the aromatic heterocyclic ring, which can be 1-4;

[0072] Ar in the ligand is the following fused ring:

[0073]

[0074] In the ligand, R1, R2, R3, and R4 are H, D, an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a fluorinated alkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a pyridyl group, a substituted pyridyl group, a carbazolyl group, a benzofuranyl group, a benzothienyl group, a condensed aromatic heterocycle having less than 12 carbon atoms, F, Cl, Br, or a secondary amine -N(RR)2 bonded to a nitrogen atom; in the secondary amine, R is an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a benzofuranyl group, a benzothienyl group, or a carbazolyl group.

[0075] In reaction formula II, complex 9 uses red-emitting phenylisoquinoline as L bidentate chelate luminescent ligand. According to the scope of the present invention, other main ligands such as quinoline bidentate chelate luminescent ligands are also applicable.

[0076] The present invention also discloses an organic electroluminescent device, which is composed of the following parts:

[0077] (a) a cathode;

[0078] (b) an electron injection layer;

[0079] (c) an anode;

[0080] (d) a hole injection layer;

[0081] (e) a light-emitting layer sandwiched between the electron injection layer and the hole injection layer, wherein the light-emitting layer contains the following metal complex (i.e., the light-emitting metal iridium complex (hybrid iridium complex) of the present invention) as shown in the general formula (1), (2), (1d), (2d):

[0082]

[0083] Wherein phenylpyridine is an auxiliary ligand, and in the auxiliary ligand, h=1-4, k=0-2, and m=1-12 in the mixed alkyl-fluoroalkyl group;

[0084] In the auxiliary ligand, Y is H, D, an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a fluorinated alkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a pyridyl group, a substituted pyridyl group, a carbazolyl group, a benzofuranyl group, a benzothienyl group, a condensed aromatic heterocycle having less than 12 carbon atoms, F, Cl, NO2, one or more chemical crosslinking groups, or a secondary amine -N(RR)2 bonded to a nitrogen atom, a secondary amine wherein R is an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a benzofuranyl group, a benzothienyl group, or a carbazolyl group;

[0085] q, m, and n are the number of substituents on the aromatic heterocyclic ring, which can be 1-4;

[0086] Ar in the ligand is the following fused ring:

[0087]

[0088] In the ligand, R1, R2, R3, and R4 are H, D, an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a fluorinated alkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a pyridyl group, a substituted pyridyl group, a carbazolyl group, a benzofuranyl group, a benzothienyl group, a condensed aromatic heterocycle having less than 12 carbon atoms, F, Cl, Br, or a secondary amine -N(RR)2 bonded to a nitrogen atom; in the secondary amine, R is an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a phenyl group, a substituted phenyl group, a fluorenyl group, a substituted fluorenyl group, a benzofuranyl group, a benzothienyl group, or a carbazolyl group.

[0089] The luminescent metal iridium complex (hybrid iridium complex) described in the present invention is applied to an organic light-emitting diode, usually by mixing a luminescent dopant compound with a host material (Host) to form a luminescent layer. The mixing of luminescent dopant compounds is beneficial to increase the efficiency of the luminescent molecules, reduce the change in luminescent color under different electric fields, and also reduce the amount of expensive luminescent dopants. The mixed film can be formed by vacuum co-evaporation, or by spin coating, spraying or solution printing by mixing and dissolving in a solution. The present invention also includes the application of the above-mentioned luminescent materials in organic light-emitting devices (OLED organic light-emitting diodes). As an organic semiconductor, in principle, the material can be used as a charge transport layer and a blocking layer. From an economic point of view, the application as a luminescent layer is more important. When used as a luminescent layer, in order to improve the luminescent efficiency, it is necessary to avoid the aggregation of luminescent molecules as much as possible and use the following general device structure, including:

[0090] a substrate material, such as glass, metal foil, or polymer film;

[0091] an anode, such as transparent conductive indium tin oxide;

[0092] a cathode, such as conductive aluminum or other metal;

[0093] One or more layers of organic semiconductor, such as an electron injection layer between the light-emitting layer and the cathode, and a hole injection layer between the light-emitting layer and the anode, wherein the emission layer contains a mixture of the phosphorescent light-emitting material and the host material. The light-emitting layer usually uses a light-emitting material with a concentration (weight) of less than 50%, preferably 0.2 to 20% dopant, and the more optimized doping concentration is 2-15%. Of course, the host material can also be a mixed host material of more than one material, in which case the smaller amount is an auxiliary host material. Yellow or green light organometallic iridium complexes can be mixed into the light-emitting layer of the organic electroluminescent device for sensitization to obtain an improved deep red organic light-emitting device. Red and blue light-doped light-emitting materials can also be doped simultaneously in the same light-emitting layer to obtain a mixed white light-emitting device.

[0094] The light-emitting layer of the light-emitting device of the present invention contains the light-emitting material, and a main material or a main material and an auxiliary main material are co-evaporated or solution coated to form a light-emitting layer; the thickness of the light-emitting layer is 5-50 nanometers, and the triplet energy level of the main material is 2.2-2.9eV, depending on the wavelength of the light. If it is blue electrophosphorescence, the triplet energy level of the main material should be greater than 2.75eV; if it is green electrophosphorescence, the triplet energy level of the main material should be greater than 2.40eV; if it is red electrophosphorescence, the triplet energy level of the main material should be greater than 2.2eV.

[0095] As a red light-emitting OLED device, many host materials reported in the literature can be used, and their energy gap Eg>2.2eV; for example, the host materials used include but are not limited to the following structural compounds:

[0096]

[0097] Advantages and beneficial effects of the present invention: The present invention uses partially fluorinated alkyl groups with solubilizing and self-lubricating effects to replace auxiliary ligands, specifically introducing fluorinated alkyl groups on the pyridine ring, such as CH2CF2CF3, CH2CF3, CF2CF2CF3, CH2CF2CF3, CF(CF3)2, CH(CF3)2, CF2CF(CF3)2, CH2CF(C

[0098] F3)2. From the perspective of obtaining better photoelectric performance, it is better to use a partially fluorinated alkyl mixture. From the perspective of obtaining better hydrophobicity, it is better to use a perfluorinated long alkane. From the perspective of comprehensive photoelectric performance and hydrophobicity, it is better to use a mixed alkyl-fluoroalkane, in which the alkyl is bonded to the phenylpyridine auxiliary ligand. The polycarbon fluoroalkane herein can also be a partially deuterated or fully deuterated alkyl-fluoroalkane mixture. Partial or fully deuterated brings about easy identification and detection of isotopes and is widely used in probes or unique light-emitting devices. In addition, partial or fully deuterated, it also slightly gives the advantages of improved stability of luminescent materials and improved application life of OLED devices. Of course, the present invention also includes the disclosure of bonding to the main light-emitting ligand. The self-lubricating function of the mixed alkyl-fluoroalkane not only increases the solubility of the conjugated iridium complex, but also reduces the sublimation temperature, making many original luminescent iridium complexes that are difficult to dissolve and sublimate and purify, such as deep red organic luminescent iridium complexes, easily soluble, easy to sublimate, and easy to scale up the evaporation to prepare OLED devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] Figure 1 Schematic diagram of the structure of an organic light emitting diode according to an embodiment. DETAILED DESCRIPTION

[0100] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with examples. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0101] Example 1: Synthesis of luminescent compound 1-13 containing 2-phenyl-6-trifluoromethylethyl-pyridine auxiliary ligand:

[0102]

[0103] 1.1 Synthesis of compound 1-13-2

[0104]

[0105] 3g 5-trifluoroethyl-2-phenylpyridine, 1.41g iridium trichloride trihydrate, 36mL 2-ethoxyethanol and 12mL distilled water were added to a 200mL three-necked flask, replaced with nitrogen three times, heated to 110 degrees, and the reaction solution refluxed vigorously. After reacting for 20 hours, the temperature was lowered to room temperature (about 30 degrees), stirred at room temperature for 0.5 hours, filtered, and the solid was washed twice with 50mL*2 methanol and 50mL*2 n-hexane, and dried to obtain 1.65g yellow solid with a yield of 84%.

[0106] 1.2 Synthesis of compound 1-13-3

[0107]

[0108] 1.2g of chlorobridge compound, 71mL of dichloromethane and 5mL of methanol were added to a 100mL reactor, replaced with nitrogen three times, stirred at room temperature for 16h, filtered through diatomaceous earth to remove silver chloride, and the solid was washed twice with 200mL of dichloromethane. The dichloromethane was concentrated to obtain 1.4g of silver salt, which was continued to the next step without treatment. The yield was 99%.

[0109] 1.3 Synthesis of Compound 1-13

[0110]

[0111] 1.2g silver salt, 1.32g ligand and 30mL ethanol were added to a 100mL three-necked flask, replaced with nitrogen 3 times, mechanically stirred, and then heated to reflux for 24 hours. After 24 hours of reaction, the temperature was lowered to room temperature (about 25°C), stirred for 0.5 hours, and then filtered. The solid was slurried with 400mL of methanol and finally passed through a silica gel column to obtain 99.5% 1-13 with a yield of 70%. Chemical formula molecule C 53 H 46 The calculated molecular weight of F6IrN3 is 1031.16, and the mass spectrometry analysis shows m / e=1031.32. The sublimation temperature of DI-Mass powder direct sampling detection is 318° C. The luminescent complex is dissolved in THF solvent of polystyrene to prepare a 5% doped film to detect the photoluminescence PL emission wavelength.

[0112] Relevant physical data

[0113]

[0114] Example 2: Synthesis of deuterated fluoroalkylphenyl-pyridine auxiliary ligand luminescent compound 1-19:

[0115]

[0116] Dissolve 3 g of 5-trifluoroethyl-2-phenylpyridine (11.94 mmol) in 15 ml of DMSO-d6 deuterated solvent, add potassium carbonate (3.3 g, 23.8 mmol), stir at 50°C for 18 hours, then evaporate the solvent under reduced pressure, add 15 ml of D2O heavy water and stir, and the oily substance after oil-water separation is subjected to reduced pressure Kugelrohr short-path distillation to obtain 2.1 g of colorless oily product 1-13-1d.

[0117]

[0118] According to the above reaction conditions, some deuterated luminescent compounds 1-19 were obtained in the same manner as in Example 1, and their properties are summarized in Table 4.

[0119] According to the above synthetic chemical principles and operating steps, without violating the scope of the present invention, the following red light-emitting organometallic iridium compounds composed of fluorine-containing substituted heteroligands and luminescent ligands were synthesized. The molecular weight and the fragments of the molecules of the specific listed complexes were verified by mass spectrometry, as shown in Table 4 below:

[0120] Table 4

[0121]

[0122]

[0123]

[0124]

[0125]

[0126] Example 3. Solubility and sublimation temperature comparison experiment:

[0127] The DI-Mass instrument was used to directly inject solid powder into the mass spectrometer to detect the sublimation temperature when the molecular mass spectrum peak appeared (at a fixed vacuum degree of 10 -5 torr), and the following sublimation temperature results were obtained:

[0128] Table 5: Sublimation temperature and solubility comparison test results:

[0129]

[0130]

[0131] The above results show that under the same luminescent structure and the same number of carbon atoms, the red-light iridium complex substituted with fluorine has the effect of reducing the sublimation temperature and increasing the solubility; in addition, the TGA thermal decomposition temperature is higher than that of the red-light iridium complex with acetylacetone auxiliary ligand. Under the same luminescent ligand condition, although the simplest acetylacetone auxiliary ligand can obtain a deeper red light, the sublimation temperature and thermal decomposition temperature of the formed complex are too close (less than 50°C), which easily leads to thermal decomposition during sublimation purification or evaporation film preparation of OLED devices. Although the thermal decomposition temperature of the luminescent complex Ref.1 using phenylpyridine auxiliary ligand is increased, the sublimation temperature is also increased due to the increase in molecular weight. The sublimation temperature and thermal decomposition temperature are also too close, which is not conducive to the evaporation film preparation process of OLED devices.

[0132] Example 4: Application example of device preparation by vacuum evaporation:

[0133] In a background vacuum up to 10 -5 The following device structure is used in the multi-source evaporation OLED preparation equipment of Pa: ITO / mTDATA / NPD / TcTa / Host: Luminescent dopant 6% / TPBi / LiF / Al, using different host materials and luminescent dopants OLED light emitting devices for comparison. The vacuum deposition speed of each organic layer and electrode is listed in Table 6.

[0134] Table 6: Preparation conditions of phosphorescent OLED devices (dopant weight concentration in the light-emitting layer 9%)

[0135]

[0136] Table 7: OLED device performance (1000Cd / cm 2 illumination); LT 80％ Lifespan h@40mA / cm 2

[0137]

[0138] From the device performance comparison in Table 7, it can be seen that compared with the luminescent material Ref.2 containing acetylacetone auxiliary ligand, the red light emitting dopant compounds 2-10, 1-13, 1-19, and 2-13 of the present invention all have higher luminous efficiency (LE, EQE), and the accelerated life LT of the obtained OLED device is 80％ (@40mA / cm 2 ) is longer. Comparing device C with device A,

[0139] The device life of the partially deuterated luminescent material 2-13 is slightly longer than that of the similar luminescent material 2-10. Comparing device D with device B, the device life of the partially deuterated luminescent material 1-19 is slightly longer than that of the similar luminescent material 1-13.

[0140] Example 5: Preparation of an organic light-emitting device OLED light-emitting layer by solution spin coating:

[0141] On a conductive glass ITO surface, after solvent and plasma cleaning, a PEDOT conductive polymer is solution-spin-coated as a hole injection layer, a poly (triphenylamine-9.9-diheptanefluorene) solution is used as a hole transport layer, and then a 2% main material X-Host / the present luminescent dopant green or red or yellow light material (doping concentration 4% by weight) mixed solution is spin-coated, and then heated to 160° C. for 30 minutes under nitrogen to make the film infusible and insoluble; then a layer of TPBi is solution-spin-coated Finally, a background vacuum of 10 -5 In the multi-source evaporation OLED preparation equipment of Pa, the electron injection layer LiF is evaporated / Al Prepare OLED devices. The main material is also a cross-linkable compound:

[0142]

[0143] Table 8: Performance of cross-linkable light-emitting layer OLED device prepared by solution spin coating:

[0144]

[0145] The performance of the above devices is similar to that of vacuum evaporation devices, but the advantage is that no vacuum operation is required to obtain the light-emitting layer, thus reducing the equipment cost.

[0146] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. An organic light-emitting device, characterized in that: The light emitting device is composed of the following parts: (a) a cathode; (b) an electron injection layer; (c) an anode; (d) a hole injection layer; (e) a light-emitting layer sandwiched between the electron injection layer and the hole injection layer, wherein the light-emitting layer contains a light-emitting organic metal iridium complex having a structure shown in the following general formula: Wherein the mixed alkyl-fluoroalkyl in the phenylpyridine auxiliary ligand has h=1-4; k=0-2, m=1-12; In the auxiliary ligand, Y is H, D, an alkyl group with less than 12 carbon atoms, a cycloalkyl group with less than 12 carbon atoms, a fluorinated alkyl group with less than 12 carbon atoms, F, Cl, NO2, or one or more chemical crosslinking groups; the chemical crosslinking groups contain styrene, acrylate or trifluorovinyl; q, m, and n are the number of substituents on the aromatic heterocyclic ring, which can be 1-4; Ar in the ligand is the following fused ring: In the ligand, R1, R2, R3, and R4 are H, D, an alkyl group having less than 12 carbon atoms, a cycloalkyl group having less than 12 carbon atoms, a fluorinated alkyl group having less than 12 carbon atoms, F, Cl, or Br; The organic electroluminescent device emits deep red light and is applied to light emitting devices with a wavelength greater than 620nm or organic full-color display screens.

2. The organic light-emitting device according to claim 1, characterized in that: In the organic light-emitting iridium metal complex of the light-emitting layer of the organic light-emitting device, Y contains at least one chemical cross-linking group, and the cross-linking group is selected from styrene, acrylate or trifluorovinyl.

3. The organic light-emitting iridium metal complex according to claim 2, characterized in that: The cross-linkable organic light-emitting complex is the following complex:

4. The organic light-emitting iridium metal complex according to claim 2 or 3, characterized in that: The cross-linkable organic light-emitting complex forms an insoluble and infusible cross-linked network structure when heated to 160° C.:

5. The organic light-emitting device according to claim 1, characterized in that: The organic light-emitting complex of the light-emitting layer in the organic light-emitting device is:

6. The organic light-emitting device according to claim 1, characterized in that: The organic light-emitting complex of the light-emitting layer in the organic light-emitting device is:

7. An organic light-emitting device, characterized in that: The light emitting device is composed of the following parts: (a) a cathode; (b) an electron injection layer; (c) an anode; (d) a hole injection layer; (e) a light-emitting layer sandwiched between the electron injection layer and the hole injection layer, wherein the light-emitting layer contains at least one light-emitting organic metal iridium complex, and the light-emitting organic metal iridium complex includes any one of the following complexes:

8. The organic light-emitting device according to claim 1 or 7, characterized in that: The organic electroluminescent device light-emitting layer can be mixed with yellow or green light-emitting organic metal iridium complex for sensitization to obtain an improved deep red organic light-emitting device.

9. The organic light-emitting device according to claim 1 or 7, characterized in that: The organic electroluminescent device can be mixed with a blue luminescent material to obtain a mixed white light luminescent device, which is applied in white light illumination or white light source.

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