Iridium complexes, methods for their preparation and use

Abstract

The present invention discloses an iridium complex and its preparation method and application, belonging to the field of display technology. The chemical structure of the iridium complex is as follows: wherein R1 and R2 are independently selected from hydrogen, halogen, -CF3, substituted or unsubstituted alkyl or cycloalkyl; R3 is selected from halogen, -CF3, -OC n F 2n+1 ,‑OC m H 2m+1 , a substituted or unsubstituted alkyl group, n is an integer from 1 to 10, and m is an integer from 1 to 10; R4 is selected from hydrogen, halogen, -CF3, -OCF3, or a substituted or unsubstituted alkyl group. The luminous efficiency and service life of the light-emitting layer based on this iridium complex are significantly improved, and it exhibits excellent thermal stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of display, in particular to an iridium complex and a preparation method and application thereof. BACKGROUND

[0002] An organic light emitting diode (OLED) is a kind of semiconductor light emitting device based on organic light emitting material, and the OLED device includes a hole transport layer, a light emitting layer and an electron transport layer, the holes generated by an anode combine with the electrons generated by a cathode in the light emitting layer through the hole transport layer and the electron transport layer, and form an exciton, and then emit light.

[0003] The iridium complex is widely used in organic electroluminescent phosphor materials due to its good phosphorescence emission, high phosphorescence emission efficiency, wide emission spectrum and strong stability.

[0004] However, when the iridium complex is used in an orange light emitting material, it is difficult to match the energy levels between the light emitting layer corresponding to the orange light emitting material and the carrier transport layer, and concentration quenching is prone to occur, which reduces the color saturation of the device and is not conducive to the comprehensive performance of the orange light device. SUMMARY

[0005] In view of this, the embodiments of the present application provide an iridium complex and a preparation method and application thereof, which can solve the above technical problems. Specifically, the technical solutions include the following:

[0006] On the one hand, an iridium complex is provided, and the chemical structural formula of the iridium complex is as follows:

[0007]

[0008] wherein R1, R2 are each independently selected from hydrogen, halogen, -CF3, substituted or unsubstituted alkyl or cycloalkyl;

[0009] R3 is selected from halogen, -CF3, -OCF3, substituted or unsubstituted alkyl, n is an integer of 1-10, and m is an integer of 1-10; n F 2n+1 , -OCF3, substituted or unsubstituted alkyl, n is an integer of 1-10, and m is an integer of 1-10; m H 2m+1 , substituted or unsubstituted alkyl, n is an integer of 1-10, and m is an integer of 1-10;

[0010] R4 is selected from hydrogen, halogen, -CF3, -OCF3, substituted or unsubstituted alkyl.

[0011] In some possible implementation manners, the alkyl contains 1-8 carbon atoms; and / or, when the alkyl is substituted by a substituent, the substituent is selected from deuterium, halogen, -CF3 or -CN.

[0012] In some possible implementation manners, the number of R3 is 1-3.

[0013] When the number of R3 is 2-3, at least one of R3 is -OC n F 2n+1 .

[0014] In some possible implementation manners, the number of R4 is 1-4.

[0015] In another aspect, a preparation method of the iridium complex is provided, and the preparation method comprises: reacting a precursor compound of a main ligand with trivalent iridium to prepare a dimer; and reacting the dimer with a precursor compound of an auxiliary ligand in one step to prepare the iridium complex.

[0016] In some possible implementation manners, the trivalent iridium is trichloride trihydrate iridium; and / or, the dimer and the precursor compound of the auxiliary ligand are reacted in the presence of potassium carbonate.

[0017] In still another aspect, an organic electroluminescent device is provided, which comprises an anode, a hole transport unit, a light-emitting layer, an electron transport unit and a cathode arranged in a stack, and the preparation raw material of the light-emitting layer comprises a host material and a dopant, and the dopant comprises any one of the iridium complexes.

[0018] In some possible implementation manners, the mass of the dopant is 3%-10% of the total mass of the host material and the dopant.

[0019] In some possible implementation manners, the host material is a carbazole-based host material.

[0020] In some possible implementation manners, the hole transport unit comprises at least one of a hole transport layer, a hole injection layer and an electron blocking layer.

[0021] The electron transport unit comprises at least one of an electron transport layer, an electron injection layer and a hole blocking layer.

[0022] The technical scheme provided by the embodiment of the present application has at least the following beneficial effects:

[0023] The iridium complex provided by the embodiment of the present application can be used as a fluorescent dopant and applied to a light-emitting layer of an OLED device. By using a dicarbonyl group as an auxiliary ligand, the light-emitting wavelength of the light-emitting layer is fine-tuned, the sublimation property is improved, and the light-emitting efficiency and thermal stability are improved. Therefore, when the dicarbonyl group as the auxiliary ligand cooperates with a phenyl quinoline group based on the main ligand, the light-emitting efficiency and service life of the light-emitting layer based on the iridium complex are significantly improved, and excellent thermal stability is exhibited. DETAILED DESCRIPTION

[0024] In order to make the technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below.

[0025] Organic Light Emitting Diodes (OLED) is a kind of semiconductor light-emitting device based on organic light-emitting material, and the OLED device at least includes a hole transport layer, a light-emitting layer and an electron transport layer. The holes generated by the anode pass through the hole transport layer to the light-emitting layer, and the electrons generated by the cathode pass through the electron transport layer to the light-emitting layer, and the holes and the electrons emit light after forming excitons in the light-emitting layer. The type of emitted light can be adjusted by changing the light-emitting material.

[0026] Generally, 25% of the excitons are in singlet excited state, and the remaining 75% of the excitons are in triplet excited state. The radiation transition paths corresponding to the two kinds of excitons are singlet fluorescence and triplet phosphorescence, respectively. The phosphorescent material can effectively utilize the triplet excitons, and theoretically, the internal quantum efficiency of the phosphorescent material is more excellent than that of the fluorescent material.

[0027] Iridium complex is a kind of organic electroluminescent phosphorescent material which is widely used. The atomic number of iridium is large, which makes the iridium complex generate strong spin-orbital coupling, which is conducive to phosphorescent emission; the d orbital level of the iridium metal ion is split large, which can avoid the interaction with the metal-ligand charge transfer (MLCT) state of the ligand, which is conducive to improving the phosphorescent emission efficiency; the trivalent ion of iridium can form a very stable neutral molecule with the ligand, which makes it conducive to using vacuum evaporation or solution processing method to prepare light-emitting device. The emission color of the iridium complex can cover the entire visible spectrum, and the stability is good, which meets the requirements of electroluminescent material. Therefore, based on the iridium complex, the phosphorescent emission is good, the phosphorescent emission efficiency is high, the emission spectrum is wide, and the stability is strong, etc., so that it becomes the research focus of the organic electroluminescent phosphorescent material.

[0028] However, when the iridium complex is used for orange light-emitting material, it will cause difficulty in energy level matching between the light-emitting layer corresponding to the orange light-emitting material and the carrier transport layer, and it is easy to cause concentration quenching, which reduces the color saturation of the device, and is not conducive to the comprehensive performance of the orange light-emitting device.

[0029] In view of the technical problems existing in the prior art, the embodiments of the present application provide an iridium complex, and the chemical structural formula of the iridium complex is as follows:

[0030]

[0031] wherein R1, R2 are each independently selected from hydrogen, halogen, -CF3, substituted or unsubstituted alkyl or cycloalkyl.

[0032] R3 is selected from the group consisting of halogen, -CF3, -OCF3, substituted or unsubstituted alkyl, n is an integer from 1 to 10, m is an integer from 1 to 10, for example, when n is 1, -OCF3, -OCH3. n F 2n+1 , -OC m H 2m+1 , substituted or unsubstituted alkyl, n is an integer from 1 to 10, m is an integer from 1 to 10, for example, when n is 1, -OC n F 2n+1 F is -OCF3, m is 1, -OCH3.

[0033] R4 is selected from the group consisting of hydrogen, halogen, -CF3, -OCF3, substituted or unsubstituted alkyl.

[0034] Each of the halogens mentioned above includes fluorine (F), chlorine (Cl), bromine (Br) or iodine (I).

[0035] For the chemical structure of the iridium complex, the iridium complex includes a main ligand and an auxiliary ligand, wherein the main ligand is a phenylquinoline group, which mainly plays a role of an electronic transition energy level, and the chemical structure of the main ligand is as follows:

[0036]

[0037] In the chemical structure, * is the binding site of the main ligand to the central coordination metal iridium (Ir).

[0038] The auxiliary ligand is a dicarbonyl group, and the chemical structure of the auxiliary ligand is as follows:

[0039]

[0040] In the chemical structure, * is the binding site of the auxiliary ligand to the central coordination metal iridium (Ir).

[0041] The iridium complex provided by the embodiment of the present application can be used as a fluorescent dopant and applied to the light-emitting layer of an OLED device. By using a dicarbonyl group as an auxiliary ligand, the light-emitting wavelength of the light-emitting layer is fine-tuned, the sublimation property is improved, and the light-emitting efficiency and thermal stability are improved. Therefore, when the dicarbonyl group as an auxiliary ligand cooperates with the phenylquinoline group based on the main ligand, the light-emitting efficiency and service life of the light-emitting layer based on the iridium complex are significantly improved, and excellent thermal stability is exhibited.

[0042] For the auxiliary ligand of the iridium complex, R1 and R2 are each independently selected from the group consisting of hydrogen, halogen, -CF3, substituted or unsubstituted alkyl or cycloalkyl. For the substituted alkyl or cycloalkyl, the hydrogen in the alkyl chain can be substituted by a substituent selected from the group consisting of deuterium, halogen, -CF3 or -CN.

[0043] For the main ligand of the iridium complex, R3 is selected from the group consisting of halogen, -CF3, -OCn F 2n+1 、-OC m H 2m+1 , substituted or unsubstituted alkyl, R4 is selected from hydrogen, halogen, -CF3, -OCF3, substituted or unsubstituted alkyl. For substituted alkyl, the hydrogen in the alkyl chain can be further substituted by a substituent selected from deuterium, halogen, -CF3, or -CN.

[0044] For R1, R2, R3, R4, in some examples, the alkyl involved can contain 1-8 carbon atoms (further the number of carbon atoms can be 1-6); and / or, when the alkyl is substituted, the substituent is selected from deuterium, halogen, -CF3, or -CN, and, when there are multiple substituents, the substituents can be the same or different.

[0045] For example, some straight chain alkyl or branched alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 2,3-dimethylpropyl, 1-ethylpropyl, 2-methyl-3-pentyl, 3,3-dimethyl-2-butyl, and the like. Further, the alkyl group can be selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, and the like.

[0046] Some examples of cycloalkyl groups include, but are not limited to, cyclobutyl, cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, and the like.

[0047] For the primary ligand of the iridium complex, R3 can be mono-substituted, di-substituted (i.e., the number of R3 is 2), or tri-substituted (i.e., the number of R3 is 3), and when R3 is di-substituted or tri-substituted, the multiple R3 substituents can be the same or different. That is, in embodiments of the present application, the number of R3 is 1-3; and when the number of R3 is 2-3, at least one R3 is -OCF3. n F 2n+1 Further, at least one R3 is -OCF3.

[0048] For the primary ligand of the iridium complex, R4 can be mono-substituted, di-substituted (i.e., the number of R4 is 2), tri-substituted (i.e., the number of R4 is 3), or tetra-substituted (i.e., the number of R4 is 4).

[0049] For the secondary ligand of the iridium complex, R1 and R2 can be mono-substituted or di-substituted, for example, when R1 and R2 are alkyl, the hydrogen on the alkyl group can be further substituted, for example, by deuterium, halogen, -CF3, or -CN.

[0050] Some examples of the main ligand and the ancillary ligand of the iridium complex are listed below, any one of the main ligand of the iridium complex can be combined with any one of the ancillary ligand of the iridium complex to form the iridium complex of a specific structure.

[0051] (I) the main ligand of the iridium complex

[0052]

[0053]

[0054]

[0055] (II) the ancillary ligand of the iridium complex

[0056]

[0057] Based on the main ligand and the ancillary ligand of the iridium complex involved above, some examples of the iridium complex can be shown as follows:

[0058]

[0059]

[0060]

[0061] In another aspect, the embodiment of the present application further provides a preparation method of any one of the above-mentioned iridium complex, the preparation method of the iridium complex comprising: (1) reacting a precursor compound of the main ligand with trivalent iridium to prepare a dimer; and (2) reacting the dimer with a precursor compound of the ancillary ligand to obtain the iridium complex.

[0062] The chemical reaction equation involved in the preparation method of the iridium complex is shown as follows:

[0063]

[0064] The trivalent iridium is trichloride iridium trihydrate; and / or the dimer and the precursor compound of the ancillary ligand are reacted in the presence of potassium carbonate, so that the reaction can be carried out smoothly.

[0065] In still another aspect, the embodiment of the present application further provides an organic electroluminescent device, which comprises an anode, a hole transport unit, a light-emitting layer, an electron transport unit and a cathode arranged in a stack, the preparation raw material of the light-emitting layer comprises a host material and a dopant, and the dopant comprises any one of the above-mentioned iridium complex.

[0066] The organic electroluminescent device provided by the embodiment of the present application can emit white light or orange light based on the use of the iridium complex, and has excellent luminous efficiency, service life and thermal stability.

[0067] In some examples, the mass of the dopant in the light-emitting layer is 3-10% of the total mass of the host material and the dopant, including but not limited to 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0068] The iridium complex involved in the embodiment of the present application can cooperate with various types of OLED host materials to emit light. Some exemplary host materials can be carbazole-based host materials. Further examples of some carbazole-based host materials include, but are not limited to, the following compounds.

[0069]

[0070] The organic electroluminescent device involved in the embodiment of the present application has a hole transport unit including at least one of a hole transport layer, a hole injection layer and an electron blocking layer, and an electron transport unit including at least one of an electron transport layer, an electron injection layer and a hole blocking layer.

[0071] For example, the structure of the organic electroluminescent device includes, but is not limited to, the following: (1) an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode; (2) an anode, a hole transport layer, a light-emitting layer, an electron transport layer and a cathode; (3) an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer and a cathode; (4) an anode, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode; (5) an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and a cathode; (6) an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode; (7) an anode, a hole injection layer, a hole transport layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and a cathode. The structure of the organic electroluminescent device can be adjusted as needed.

[0072] The anode, the hole injection layer, the hole transport layer, the electron transport layer, the electron injection layer and the cathode are all functional layers known in the art and can be prepared using known related materials.

[0073] For other functional layers in the organic electroluminescent device except for the anode and the cathode, they can be prepared by the following methods: vacuum evaporation method, molecular beam evaporation method, solvent-dissolved dip-coating method, spin-coating method, bar coating method, inkjet printing, etc. For the anode and the cathode, since they are metal electrodes, both of them can be prepared by using evaporation method or sputtering method.

[0074] The organic electroluminescent device related to the embodiments of the present application can be used for preparing display devices or light-emitting illumination light sources, etc., and the prepared display devices or light sources have excellent light-emitting efficiency, service life and thermal stability.

[0075] Exemplarily, the organic electroluminescent device provided by the embodiments of the present application can be applied in the following scenarios: computers, tablet computers, televisions, telephones, virtual reality or augmented reality displays, etc.

[0076] The preferred embodiments of the present application will be described in more detail below. Although the preferred embodiments of the present application are described below, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. In the examples, no specific techniques or conditions are specified, and the techniques or conditions described in the literature in the art or according to the product instructions are used. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained commercially.

[0077] Example 1

[0078] Example 1 prepared an iridium complex (i.e. RDP-1 related above), and the preparation equation of the RDP-1 iridium complex is as follows:

[0079]

[0080] The preparation method of the RDP-1 iridium complex is as follows:

[0081] 5.46 g of precursor compound RD-14 of the main ligand and 3.54 g of iridium trichloride trihydrate (IrCl3(H2O)3) were added to a round-bottom flask, then 30 mL of water and 90 mL of ethylene glycol ethyl ether were added, and the reaction was stirred under reflux at 115°C for 12 h under nitrogen protection. Stop heating, filter the obtained mixture, collect the filter cake, and wash the filter cake with water, ethanol and methyl tert-butyl ether in sequence to obtain a deep orange dimer.

[0082] The deep orange dimer was directly added into a round bottom flask without any further treatment, 100 mL of dichloromethane was added as solvent, then 7.88 g of potassium carbonate and 2.36 g of the precursor compound of the auxiliary ligand RP-1 were added, the reaction was stirred at room temperature for 12 h, then the stirring was stopped, the obtained solution was evaporated to dryness, and column chromatography was used to separate the orange powdery solid 7.06 g, which was the orange powdery solid of the iridium complex, and the HPLC (iPrOH 10%, MeOH 90%, 1 mL / min, 365 nm) detection purity was 99.52%.

[0083] The hydrogen spectrum test results of the iridium complex are as follows:

[0084] 1 H NMR (400 MHz, Chloroform-d) δ 8.70 (d, J = 8.5 Hz, 2H), 8.26 (s, 2H), 8.08 (dd, J = 8.3, 1.4 Hz, 2H), 7.51 (dd, J = 8.6, 2.3 Hz, 2H), 7.40 - 7.31 (m, 2H), 7.18 (ddd, J = 8.3, 7.1, 1.2 Hz, 2H), 7.05 (dd, J = 7.6, 1.3 Hz, 2H), 6.72 (d, J = 2.1 Hz, 2H), 5.87 (d, J = 1.8 Hz, 1H), 3.87 (s, 6H), 2.84 (p, J = 4.6 Hz, 1H), 2.66 (pd, J = 4.0, 1.7 Hz, 1H), 1.09 (dd, J = 5.1, 4.3 Hz, 12H).

[0085] Example 2

[0086] Example 2 prepared an iridium complex (i.e. RDP-5 mentioned above), and the preparation equation of the RDP-5 iridium complex is as follows:

[0087]

[0088] The preparation method of the RDP-5 iridium complex can refer to the preparation method of the RDP-1 iridium complex in Example 1, which will not be described here.

[0089] The RDP-5 iridium complex was tested to be an orange powdery solid, 6.84 g, and the HPLC detection purity was 99.63%, and the hydrogen spectrum test results are as follows:

[0090] 1H NMR (400 MHz, Chloroform-d) δ 8.70 (d, J = 8.5 Hz, 2H), 8.26 (s, 2H), 8.08 (dd, J = 8.3, 1.4 Hz, 2H), 7.51 (dd, J = 8.6, 2.3 Hz, 2H), 7.40 - 7.31 (m, 2H), 7.18 (ddd, J = 8.3, 7.1, 1.2 Hz, 2H), 7.05 (dd, J = 7.6, 1.3 Hz, 2H), 6.72 (d, J = 2.1 Hz, 2H), 5.87 (d, J = 1.8 Hz, 1H), 3.87 (s, 6H), 2.84 (p, J = 4.6 Hz, 1H), 2.66 (pd, J = 4.0, 1.7 Hz, 1H), 1.09 (dd, J = 5.1, 4.3 Hz, 12H).

[0091] Example 3

[0092] Example 3 prepared an iridium complex (i.e. RDP-12 referred to above), the preparation equation of which is shown as follows:

[0093]

[0094] The preparation method of the RDP-12 iridium complex can refer to the preparation method of the RDP-1 iridium complex in Example 1, which is not described herein again.

[0095] It is tested that the RDP-12 iridium complex is an orange powdery solid, 5.96 g, the purity of which is 99.43% detected by HPLC, and the hydrogen spectrum test result of which is shown as follows:

[0096] 1 H NMR (400 MHz, Chloroform-d) δ 8.83 (d, J = 8.5 Hz, 2H), 8.45 (d, J = 7.9 Hz, 2H), 7.55 (dd, J = 8.6, 2.1 Hz, 2H), 7.18 (dd, J = 8.0, 2.4 Hz, 2H), 6.99 (t, J = 2.3 Hz, 2H), 6.75 (d, J = 2.1 Hz, 2H), 6.66 (d, J = 2.1 Hz, 2H), 5.93 (d, J = 1.8 Hz, 1H), 2.68 (p, J = 9.5 Hz, 1H), 2.54 - 2.40 (m, 1H), 1.68 - 1.47 (m, 8H), 0.93 - 0.85 (m, 12H).

[0097] Example 4

[0098] Example 4 prepared an iridium complex (i.e. RDP-21 referred to above), the preparation equation of which is shown as follows:

[0099]

[0100] The preparation method of the RDP-21 iridium complex can refer to the preparation method of the RDP-1 iridium complex in Example 1, which is not described here again.

[0101] Test results show that the RDP-21 iridium complex is an orange powdery solid, 6.76 g, and its HPLC detection purity is 99.58%, and its hydrogen spectrum test results are as follows:

[0102] 1 H NMR (400 MHz, Chloroform-d) δ 8.64 (d, J = 8.6 Hz, 2H), 8.34 (dd, J = 8.2, 1.2 Hz, 2H), 7.86 (d, J = 8.5 Hz, 2H), 7.32 (t, J = 7.9 Hz, 2H), 7.23 (dd, J = 7.7, 1.4 Hz, 2H), 7.07 - 7.02 (m, 2H), 6.87 (d, J = 2.2 Hz, 2H), 5.87 (d, J = 1.8 Hz, 1H), 3.22 - 3.11 (m, 2H), 2.58 - 2.45 (m, 1H), 1.59 (m, 4H), 1.24 (d, J = 4.6 Hz, 12H), 1.17 (s, 6H), 0.88 (t, J = 4.4 Hz, 6H).

[0103] Example 5

[0104] Example 5 prepared an iridium complex (i.e. the above-mentioned RDP-27), and the preparation equation of the RDP-27 iridium complex is as follows:

[0105]

[0106] The preparation method of the RDP-27 iridium complex can refer to the preparation method of the RDP-1 iridium complex in Example 1, which is not described here again.

[0107] Test results show that the RDP-27 iridium complex is an orange powdery solid, 6.91 g, and its HPLC detection purity is 99.79%, and its hydrogen spectrum test results are as follows:

[0108] 1H NMR (400 MHz, Chloroform-d) δ 8.85 (d, J = 8.5 Hz, 2H), 8.56 - 8.40 (m, 2H), 7.93 (t, J = 1.2 Hz, 2H), 7.56 (dd, J = 8.5, 2.2 Hz, 2H), 7.18 (dd, J = 8.0, 2.4 Hz, 2H), 7.13 (d, J = 1.1 Hz, 4H), 6.98 (t, J = 2.3 Hz, 2H), 5.84 (s, 1H), 3.10 - 2.88 (m, 1H), 1.91 - 1.58 (m, 12H), 1.06 (s, 3H), 0.83 (t, J = 4.7 Hz, 6H).

[0109] Example 6

[0110] Example 6 prepared an iridium complex (i.e. RDP-45 referred to above), the preparation equation of which is shown as follows:

[0111]

[0112] The preparation method of the RDP-45 iridium complex can refer to the preparation method of the RDP-1 iridium complex in Example 1, which is not described here again.

[0113] It was tested that the RDP-45 iridium complex was an orange powder solid, 7.15 g, the purity of which was 99.76% detected by HPLC, and the hydrogen spectrum test results thereof were as follows:

[0114] 1 H NMR (400 MHz, Chloroform-d) δ 8.85 (d, J = 8.5 Hz, 2H), 8.56 - 8.40 (m, 2H), 7.93 (t, J = 1.2 Hz, 2H), 7.56 (dd, J = 8.5, 2.2 Hz, 2H), 7.18 (dd, J = 8.0, 2.4 Hz, 2H), 7.13 (d, J = 1.1 Hz, 4H), 6.98 (t, J = 2.3 Hz, 2H), 5.84 (s, 1H), 3.10 - 2.88 (m, 1H), 1.91 - 1.58 (m, 12H), 1.06 (s, 3H), 0.83 (t, J = 4.7 Hz, 6H).

[0115] Application Example

[0116] Based on the iridium complexes prepared in Example 1 to Example 6, organic electroluminescent devices (corresponding to Application Examples 1 to 6, respectively) were prepared, which include the following layers: anode / hole injection layer / hole transport layer / electron blocking layer / light-emitting layer / electron transport layer / electron injection layer / cathode, which were sequentially stacked.

[0117] The preparation methods of the organic electroluminescent devices are shown as follows, respectively:

[0118] (1) A transparent conductive ITO glass substrate (with an anode thereon) (Nippon Sheet Glass Co., Ltd.) was subjected to ultrasonic treatment in a commercial cleaning agent, then washed in deionized water, and then sequentially washed in ethanol, acetone and deionized water, baked in a clean environment until completely free of moisture, washed with ultraviolet light and ozone, and then treated with oxygen plasma for 30 seconds, for standby use.

[0119] (2) The glass substrate with an anode after the above treatment was placed in a vacuum chamber, vacuumized, and HIL was evaporated on the ITO to form a hole injection layer with a thickness of 10 nm, at an evaporation rate of 0.1 nm / s.

[0120] (3) Compound HT was evaporated on the hole injection layer to form a hole transport layer with a thickness of 100 nm, at an evaporation rate of 0.1 nm / s, and EB was continuously evaporated to form an electron blocking layer with a thickness of 50 nm, at an evaporation rate of 0.1 nm / s.

[0121] (4) A light-emitting layer with a thickness of 35 nm was evaporated on the electron blocking layer, wherein the light-emitting layer includes a host material and a dopant, the mass percentage of the dopant is 5%, the host material is OH, and the dopant is the iridium complex provided in Example 1 to Example 6, respectively, at an evaporation rate of 0.1 nm / s.

[0122] (5) Compound ET:LiQ (weight ratio of 50:50) with a thickness of 35 nm was evaporated on the light-emitting layer as an electron transport layer, at an evaporation rate of 0.1 nm / s, LiQ with a thickness of 1 nm was continuously evaporated as an electron injection layer, and Al with a thickness of 100 nm was evaporated as a cathode.

[0123] The chemical structural formulas of each compound involved in the above functional layers are shown as follows.

[0124]

[0125]

[0126] Comparative Example 1

[0127] An organic electroluminescent device is provided, which differs from the application examples only in that the iridium complex Ir1 is used instead of the iridium complex involved in Embodiment 1-Embodiment 6. Among them, the chemical structural formula of the iridium complex Ir1 is as shown below.

[0128]

[0129] Test example

[0130] The organic electroluminescent devices provided for the application examples and comparative examples are measured by PR-655 Photo Research Spectral Scanning Chromatograph to measure the working voltage, current efficiency, CIE coordinates of these organic electroluminescent devices at 10 mA / cm 2 2 The working time when the luminance becomes 90% of the initial luminance at a current density of 50 mA / cm

[0131] Table 1

[0132]

[0133] As can be seen from Table 1, based on the use of the iridium complex provided in the embodiments of the present application, the prepared organic electroluminescent device has at least the following advantages: the relative larger emission wavelength makes the orange light saturation stronger. At the same current density, compared with Comparative Example 1, the working voltage is relatively lower, the current efficiency is higher and the service life is longer.

[0134] The above is only to facilitate those skilled in the art to understand the technical solutions of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.​

Claims

1. An iridium complex, characterized in that The chemical structural formula of the iridium complex is shown below: wherein R1 and R2 are each independently selected from hydrogen, halogen, -CF3, a substituted or unsubstituted alkyl or cycloalkyl group of 1 to 8 carbon atoms; R3 is selected from halogen, -CF3, -OC n F 2n+1 、-OC m H 2m+1 , a substituted or unsubstituted alkyl group of 1 to 8 carbon atoms, n is an integer of 1 to 10, m is an integer of 1 to 10, and at least one R3 is -OCF3; R4 is selected from hydrogen, halogen, -CF3, -OCF3, substituted or unsubstituted alkyl of 1 to 8 carbon atoms; When the alkyl or cycloalkyl group is substituted with a substituent, the substituent is selected from deuterium, halogen, -CF3 or -CN.

2. The iridium complex according to claim 1, characterized in that The number of R3 is 1-3; When the number of R3 is 2-3, at least one of the R3 is -OC n F 2n+1 .

3. The iridium complex according to claim 1, characterized in that The number of R4 is 1-4.

4. The method for preparing the iridium complex according to any one of claims 1 to 3, wherein The preparation method comprises: The precursor compound of the main ligand is reacted with trivalent iridium to prepare a dimer; and the dimer is reacted with the precursor compound of the auxiliary ligand in one step to prepare an iridium complex.

5. The method for preparing an iridium complex according to claim 4, wherein The trivalent iridium is iridium trichloride trihydrate; and / or, The dimer reacts with the precursor compound of the auxiliary ligand in the presence of potassium carbonate.

6. An organic electroluminescent device, characterized in that: The organic electroluminescent device comprises a stacked anode, a hole transport unit, a light-emitting layer, an electron transport unit and a cathode. The raw materials for preparing the light-emitting layer comprise a host material and a dopant, and the dopant comprises the iridium complex according to any one of claims 1 to 3.

7. The organic electroluminescent device according to claim 6, characterized in that: The mass of the dopant is 3%-10% of the total mass of the host material and the dopant.

8. The organic electroluminescent device according to claim 6, characterized in that: The main material is a carbazole main material.

9. The organic electroluminescent device according to claim 6, characterized in that: The hole transport unit includes at least one of a hole transport layer, a hole injection layer, and an electron blocking layer; The electron transport unit includes at least one of an electron transport layer, an electron injection layer, and a hole blocking layer.

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