A series electroluminescent device and its application in the field of optoelectronics

Abstract

The present invention discloses a tandem electroluminescent device, comprising an anode, a cathode, at least two electroluminescent units arranged between the anode and the cathode, and a charge generation layer arranged between the electroluminescent units, wherein the charge generation layer at least comprises an n-type charge generation layer (n-CGL), wherein the n-type charge generation layer comprises an at least partially reduced n-type organic semiconductor material and a metal interlayer cation. The present invention further discloses a method for preparing a tandem electroluminescent device, wherein the n-type organic semiconductor material is reduced with a bimetallic sandwich compound to produce effective n-type doping and form two metal interlayer cations. The tandem electroluminescent device disclosed in the present invention can be used in fields such as display and lighting.

Description

Technical Field

[0001] The invention relates to a series electroluminescent device, a preparation method thereof, and application thereof in the field of optoelectronics. Background Art

[0002] Organic light-emitting diodes (OLEDs) have great potential for applications in optoelectronic devices such as flat-panel displays and lighting due to the synthetic versatility, relatively low manufacturing cost, and excellent optical and electrical properties of organic semiconductor materials.

[0003] Organic electroluminescence refers to the phenomenon of converting electrical energy into light energy using organic substances. Organic electroluminescent elements that use organic electroluminescence usually have a structure with a positive electrode and a negative electrode and an organic layer between them. In order to improve the efficiency and life of organic electroluminescent elements, the organic layer has a multilayer structure, and each layer contains different organic substances. Specifically, it can include a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, etc. In this organic electroluminescent element, when a voltage is applied between the two electrodes, holes are injected from the positive electrode into the organic layer, and electrons are injected from the negative electrode into the organic layer. When the injected holes and electrons meet in the light-emitting layer, excitons are formed, and light is emitted when the excitons transition back to the ground state. This organic electroluminescent element has the characteristics of self-luminescence, high brightness, high efficiency, low driving voltage, wide viewing angle, high contrast, and fast response speed. In order to prepare OLED devices with lower driving voltage, better luminous efficiency, and longer device life, continuous innovation of organic materials, device structures, and manufacturing processes is required.

[0004] At present, in order to achieve higher brightness and solve the patterning technology of large-size OLEDs, tandem OLEDs are usually used, that is, OLEDs with a stacked structure of multiple light-emitting units. A charge generation layer is usually used to connect different light-emitting units to ensure that the charge can be effectively distributed to each sub-light-emitting unit and at the same time improve the current efficiency of each sub-light-emitting unit. This type of charge generation layer generally includes an n-type charge generation layer and a p-type charge generation layer, wherein the n-type charge generation layer generally includes an n-type organic semiconductor material (or electron transport material) and an n-type doping material. Commonly used n-type doping materials include alkali metals or alkaline earth metals or rare earth materials, such as ytterbium. The metal cations formed by these doping elements after doping may diffuse to the adjacent p-type charge generation layer, resulting in a reduced lifespan.

[0005] In addition, the organic light-emitting diode (OLED), which is currently a new generation of display technology, is prepared by evaporation. Its preparation process involves a large number of vacuum processes, low material utilization, and requires a fine mask (FMM), which is costly and has a low yield. In order to solve the above problems, the technology of using printing technology to achieve high-resolution full-color display has attracted more and more attention. For example, inkjet printing can prepare functional material films on a large area and at low cost. Compared with traditional semiconductor production processes, inkjet printing has low energy consumption, low water consumption, and is green and environmentally friendly. It is a production technology with great advantages and potential. In order to improve brightness and life, tandem printing of OLED is an attractive technical path, but the commonly used metal n-type doped materials cannot be formed into films by solution method.

[0006] Therefore, new n-type doped materials need to be developed urgently. Summary of the invention

[0007] In view of the above-mentioned deficiencies of the prior art, the object of the present invention is to provide a tandem electroluminescent device, in particular a tandem OLED device, wherein the n-type charge generation layer comprises an n-type organic semiconductor material and a metal sandwich cation. The present invention further discloses a method for preparing a tandem electroluminescent device, wherein the n-type organic semiconductor material is reduced with a bimetallic sandwich compound to produce effective n-type doping.

[0008] The specific technical solutions are as follows:

[0009] The present invention provides a tandem electroluminescent device, comprising an anode, a cathode, at least two electroluminescent units arranged between the anode and the cathode, and a charge generation layer (CGL) arranged between the electroluminescent units, wherein the charge generation layer at least comprises an n-type charge generation layer (n-CGL), wherein the n-type charge generation layer comprises an n-type organic semiconductor material and a metal interlayer cation, wherein the n-type organic semiconductor material is at least partially reduced, and the metal interlayer cation is selected from the following structures shown in general formulas (I-1) to (I-3):

[0010]

[0011] Where: M 1 Selected from manganese or rhenium, M 2 is selected from iron, ruthenium or osmium, M 3 is selected from cobalt, rhodium or iridium; x1 is an integer between 1 and 5, x2 is an integer between 1 and 4, y1 is an integer between 1 and 6, and y2 is an integer between 1 and 5;

[0012] R 1 , R 2 , R dEach occurrence is independently selected from H, D, or a linear alkyl, alkoxy, thioalkoxy group having 1 to 20 C atoms, or a branched or cyclic alkyl, alkoxy, thioalkoxy, silyl group having 3 to 20 C atoms, or a keto group having 1 to 20 C atoms, or an alkoxycarbonyl group having 2 to 20 C atoms, or an aryloxycarbonyl group having 7 to 20 C atoms, or a cyano group, a carbamoyl group, a haloformyl group, a formyl group, an isocyano group, an isocyanate group, a thiocyanate group, an isothiocyanate group, a hydroxyl group, a nitro group, CF3, Cl, Br, F, a crosslinkable group, or a substituted or unsubstituted aromatic group or heteroaromatic group having 5 to 60 ring atoms, or an aryloxy group or heteroaryloxy group having 5 to 60 ring atoms, or a combination of these groups.

[0013] The present invention also provides a method for preparing a tandem electroluminescent device, wherein an anode, a first electroluminescent unit, an n-type charge generation layer, a second electroluminescent unit and a cathode are sequentially deposited on a substrate, wherein the n-type charge generation layer is prepared as follows:

[0014] 1) co-evaporating an n-type organic semiconductor material and a bimetallic sandwich compound onto a first electroluminescent unit by vacuum thermal evaporation to form a solid film, wherein the bimetallic sandwich compound comprises a structure represented by one of the following general formulae (II-1) to (II-3); or dispersing or dissolving the n-type organic semiconductor material and the bimetallic sandwich compound in an organic solvent to form a liquid solution or dispersion, then coating the liquid solution or dispersion onto the first electroluminescent unit, and removing the organic solvent to form a solid film;

[0015]

[0016] Where: M 1 、M 2 、M 3 , x1, x2, y1, y2, R 1 , R 2 , R d is defined as above;

[0017] 2) A redox reaction occurs in the solid film, causing at least a portion of the n-type organic semiconductor material to gain electrons, and the bimetallic sandwich compound to lose electrons to form two metal interlayer cations, and the two metal interlayer cations correspond to structures selected from one of the general formulas (I-1) to (I-3).

[0018] The present invention also provides a composition comprising at least one bimetallic sandwich compound as shown in general formula (II-1) to (II-3), and at least one organic solvent.

[0019] Beneficial effects: According to the tandem electroluminescent device of the present invention, the n-type charge generation layer contains a metal sandwich cation, which is relatively large and not easy to diffuse into adjacent functional layers, such as the p-type charge generation layer, thereby improving the performance and stability of the device. Furthermore, according to the preparation method of the present invention, a bimetallic sandwich compound is used as a precursor of the n-type dopant, and a film can be formed by either evaporation or solution processing, thereby greatly broadening the technical options and process windows. The present invention innovatively provides a solution-based tandem electroluminescent device and a preparation method thereof, especially providing a new technical path for high-performance printed OLEDs and QD-LEDs (quantum dot light-emitting diodes). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 :Schematic diagram of the structure of a tandem electroluminescent device;

[0021] In the figure: 1, first electroluminescent unit; 1-1, HIL1; 1-2, HTL1; 1-3, EML1; 1-4, ETL1; 2, second electroluminescent unit; 2-1, HTL2; 2-2, EML2; 2-3, ETL2; 3, anode; 4, n-CGL; 5, p-CGL; 6, cathode. DETAILED DESCRIPTION

[0022] The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0024] In the description of the embodiments of the present invention, a numerical range represented by “~” refers to a range that includes the numerical values ​​described before and after “~” as the lower limit and the upper limit.

[0025] In the description of the embodiments of the present invention, a substituent may be further substituted by a substituent, and "substituted group a" may refer to group a being substituted by a substituent, and the substituent may be substituted by at least one further substituent or may be unsubstituted.

[0026] In the present invention, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple, respectively.

[0027] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0028] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0029] The term "OLED" is an abbreviation for "Organic Light Emitting Diode", which means organic electroluminescent diode, also known as organic electric laser display, organic light-emitting semiconductor (Organic Electroluminescence Display, OLED). OLED is a current-type organic light-emitting device, which emits light through the injection and recombination of carriers, and the luminous intensity is proportional to the injected current. Under the action of the electric field, the holes generated by the anode and the electrons generated by the cathode of the OLED will move, inject into the hole transport layer and the electron transport layer respectively, and migrate to the light-emitting layer. When the two meet in the light-emitting layer, energy excitons are generated, thereby exciting the light-emitting molecules to ultimately produce visible light.

[0030] In the present invention, n-type organic semiconductor, electron transport material, and ETM have the same meaning and can be interchanged.

[0031] In the present invention, p-type organic semiconductor, hole transport material, and HTM have the same meaning and can be interchanged.

[0032] In the present invention, polymer, polymer and polymer material have the same meaning and can be used interchangeably.

[0033] In the present invention, composition, printing ink, ink, and ink have the same meaning and can be interchangeable.

[0034] In the present invention, "alkali metal" refers to an element of Group 1. For example, the alkali metal may be lithium (Li), sodium (Na), potassium (K), rubidium (Rb), or cesium (Cs).

[0035] In the present invention, "alkaline earth metal" refers to an element of Group 2. For example, the alkaline earth metal may be magnesium (Mg), calcium (Ca), strontium (Sr), or barium (Ba).

[0036] The term "small molecule" as defined herein refers to a molecule that is not a polymer, oligomer, dendrimer, or blend. In particular, there is no repeating structure in a small molecule. The molecular weight of a small molecule is ≤3000 g / mol, preferably ≤2000 g / mol, and most preferably ≤1500 g / mol.

[0037] An oligomer is a short polymer composed of a small number of repeating structural units connected by covalent bonds; the number of its repeating structural units is generally less than 20, usually 3 to 20.

[0038] Polymers include homopolymers, copolymers, and block copolymers. For the purpose of the present invention, the polymers in the present invention also include oligomers. In addition, in the present invention, polymers also include dendrimers. For the synthesis and application of dendrimers, please refer to [Dendrimers and Dendrons, Wiley-VCH Verlag GmbH & Co. KGaA, 2002, Ed. George R. Newkome, Charles N. Moorefield, Fritz Vogtle.].

[0039] A conjugated polymer is a polymer whose main chain is mainly composed of sp 2 Hybrid orbitals are formed. Famous examples include polyacetylene and poly(phenylene vinylene). The C atoms on the main chain can also be replaced by other non-C atoms. 2 When the hybridization is interrupted by some natural defects, it is still considered as a conjugated polymer. In addition, the main chain of the conjugated polymer in the present invention contains aryl amine, aryl phosphine and other heteroaromatics, organometallic complexes, etc.

[0040] The present invention discloses a tandem electroluminescent device, comprising an anode, a cathode, at least two electroluminescent units arranged between the anode and the cathode, and a charge generation layer (CGL) arranged between the electroluminescent units, wherein the charge generation layer at least comprises an n-type charge generation layer, wherein the n-type charge generation layer comprises an n-type organic semiconductor material and a metal interlayer cation, wherein the n-type organic semiconductor material is at least partially reduced, and the metal interlayer cation is selected from the following structures shown in general formulas (I-1) to (I-3):

[0041]

[0042] Where: M 1 Selected from manganese or rhenium, M 2 is selected from iron, ruthenium or osmium, M 3 is selected from cobalt, rhodium or iridium; x1 is an integer between 1 and 5, x2 is an integer between 1 and 4, y1 is an integer between 1 and 6, and y2 is an integer between 1 and 5;

[0043] R 1 , R 2 , R d Each occurrence is independently selected from H, D, or a linear alkyl, alkoxy, thioalkoxy group having 1 to 20 C atoms, or a branched or cyclic alkyl, alkoxy, thioalkoxy, silyl group having 3 to 20 C atoms, or a keto group having 1 to 20 C atoms, or an alkoxycarbonyl group having 2 to 20 C atoms, or an aryloxycarbonyl group having 7 to 20 C atoms, or a cyano group, a carbamoyl group, a haloformyl group, a formyl group, an isocyano group, an isocyanate group, a thiocyanate group, an isothiocyanate group, a hydroxyl group, a nitro group, CF3, Cl, Br, F, a crosslinkable group, or a substituted or unsubstituted aromatic group or heteroaromatic group having 5 to 60 ring atoms, or an aryloxy group or heteroaryloxy group having 5 to 60 ring atoms, or a combination of these groups.

[0044] In the embodiments of the present invention, the energy level structure of the organic material, such as HOMO, LUMO, triplet energy level (T1) and singlet energy level (S1), plays an important role. The determination of these parameters is introduced below.

[0045] HOMO and LUMO energy levels can be measured by photoelectric effects, such as XPS (X-ray photoelectron spectroscopy) and UPS (ultraviolet photoelectron spectroscopy) or by cyclic voltammetry (hereafter referred to as CV). Recently, quantum chemical methods, such as density functional theory (hereafter referred to as DFT), have also become effective methods for calculating molecular orbital energy levels.

[0046] The triplet energy level T1 of the organic material can be measured by low-temperature time-resolved luminescence spectroscopy, or calculated by quantum simulation (such as by Time-dependent DFT), such as by commercial software Gaussian 09W (Gaussian Inc.), and the specific simulation method is described below. The singlet energy level S1 of the organic material can be determined by absorption spectrum or emission spectrum, and can also be calculated by quantum simulation (such as Time-dependent DFT).

[0047] It should be noted that the absolute values ​​of HOMO, LUMO, T1, and S1 depend on the measurement method or calculation method used. Even for the same method, different evaluation methods, such as the starting point and the peak point on the CV curve, can give different HOMO / LUMO values. Therefore, a reasonable and meaningful comparison should be made using the same measurement method and the same evaluation method. In the description of the embodiments of the present invention, the values ​​of HOMO, LUMO, T1, and S1 are based on the simulation of Time-dependent DFT, but do not affect the application of other measurement or calculation methods.

[0048] In a preferred embodiment, the metal interlayer cations according to the general formulae (I-1) to (I-3) have an 18-electron system. According to quantum mechanics, the 18-electron system is the most stable, and thus is beneficial to the stability of the compound and the device.

[0049] In some preferred embodiments, R 1 , R 2 , R d There is no conjugated group or aromatic group or heteroaromatic group connected in a conjugated manner to the five-ring or six-ring in the general formulae (I-1) to (I-3).

[0050] In some preferred embodiments, R 1 , R 2 , R d Each occurrence is independently selected from linear alkyl, alkoxy, thioalkoxy having 1 to 10 C atoms, or branched or cyclic alkyl, alkoxy, thioalkoxy, silyl having 3 to 10 C atoms, or keto having 1 to 10 C atoms, or alkoxycarbonyl having 2 to 10 C atoms, or aryloxycarbonyl having 7 to 10 C atoms, or cyano, carbamoyl, haloformyl, formyl, isocyano, isocyanate, thiocyanate, isothiocyanate, hydroxyl, nitro.

[0051] In some preferred embodiments, R 1 , R 2 , R dEach occurrence is independently selected from linear alkyl, alkoxy, thioalkoxy having 1 to 8 C atoms, or branched or cyclic alkyl, alkoxy, thioalkoxy, silyl having 3 to 8 C atoms, or keto having 1 to 8 C atoms, or alkoxycarbonyl having 2 to 8 C atoms, or aryloxycarbonyl having 7 to 8 C atoms, or cyano, carbamoyl, haloformyl, formyl, isocyano, isocyanate, thiocyanate, isothiocyanate, hydroxyl, nitro.

[0052] In a particularly preferred embodiment, the metal interlayer cation is selected from the following structures:

[0053]

[0054] Where: x1, x2, y1, y2, R 1 , R 2 , R d The definition of is as above.

[0055] According to the tandem electroluminescent device of the present invention, the n-CGL contains an n-type organic semiconductor material (i.e., ETM). Any metal complex or organic compound with electron transport capability may be used as ETM. Preferred organic ETM materials may be selected from tris(8-hydroxyquinoline)aluminum (AlQ3), phenazine, phenanthroline, anthracene, phenanthrene, fluorene, difluorene, spirobifluorene, p-phenylenevinylene, pyridazine, pyrazine, triazine, triazole, imidazole, quinoline, isoquinoline, quinoxaline, oxazole, isoxazole, oxadiazole, thiadiazole, pyridine, pyrazole, pyrrole, pyrimidine, acridine, pyrene, perylene, trans-indenofluorene, cis-indeno, dibenzo-indenofluorene, indenonaphthalene, benzanthracene, nitrogen phosphocyclopentadiene, nitrogen borocyclopentadiene, aromatic ketones, lactams, and their derivatives.

[0056] In one aspect, compounds useful as ETMs contain at least one F, cyano, or electron withdrawing group as follows:

[0057]

[0058] Where n0 is 1, 2 or 3; X 1 -X 10 Independently selected from CR 3 or N, wherein two adjacent ones cannot be N at the same time, and at least one is N; M1, M2, M3 are independently selected from N(R 8 )、C(R 8 )2、Si(R 8 )2、O、C=N(R 8 )、C=C(R 8 2. P(R 8 )、P(=O)R 8, S, S=O, SO2 or none; R 3 , R 4 , R 5 , R 6 , R 7 , R 8 The meaning is the same as above R 1 .

[0059] In a particularly preferred embodiment, a suitable ETM comprises at least one of the following groups:

[0060]

[0061] On the other hand, examples of metal complexes that can be used as ETMs include, but are not limited to, the following general structure:

[0062]

[0063] (ON) or (NN) is a bidentate ligand in which the metal is coordinated to O,N or N,N; L is an ancillary ligand; m is an integer ranging from 1 to the maximum coordination number of the metal.

[0064] In a particularly preferred embodiment, the n-type organic semiconductor material (ie, ETM) is selected from the following structures, which may be further substituted arbitrarily:

[0065]

[0066] In another preferred embodiment, the n-CGL may further comprise an organic alkali metal compound. In the present invention, the organic alkali metal compound may be understood as a compound containing at least one alkali metal, namely lithium, sodium, potassium, rubidium, cesium, and further comprising at least one organic ligand.

[0067] Suitable organic alkali metal compounds include those described in US Pat. No. 7,767,317 B2, EP 1,941,562 B1 and EP 1,144,543 B1.

[0068] The organic alkali metal compounds shown below are preferred:

[0069]

[0070] Wherein R has the same meaning as above 1 The arcs represent two or three atoms and their bonding, so as to form a five-membered or six-membered ring with the metal M1, where the atoms can also be composed of one or more R 1 Substitution, M1 is an alkali metal selected from lithium, sodium, potassium, rubidium or cesium.

[0071] The organic alkali metal compound may be in the form of a monomer, as described above, or in the form of an aggregate, for example, two alkali metal ions and two ligands, four alkali metal ions and four ligands, six alkali metal ions and six ligands or in other forms.

[0072] The preferred organic alkali metal compound is a compound of the following formula:

[0073]

[0074] Wherein, M1 and R have the same meanings as described above; o1 and o2 can be the same or different at each occurrence, and can be selected from 0, 1, 2, 3 or 4; p1, p2, p3 can be the same or different at each occurrence, and can be selected from 0, 1, 2 or 3.

[0075] In a preferred embodiment, the alkali metal M1 is selected from lithium, sodium or potassium, more preferably lithium or sodium, most preferably lithium.

[0076] Examples of suitable organic alkali metal compounds are listed below:

[0077]

[0078] In certain preferred embodiments, the tandem electroluminescent device, wherein the charge generation layer (CGL) comprises a p-type charge generation layer (p-CGL).

[0079] In certain particularly preferred embodiments, wherein the p-CGL comprises a p-type dopant material (p-dopant), the LUMO of the p-type dopant material is ≤-4.9 eV, preferably ≤-5.0 eV, more preferably ≤-5.1 eV, and most preferably ≤-5.2 eV.

[0080] Any organic compound may be used as a p-type doping material as long as they are strong electron acceptors. Take the hole transport material NPB (N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine) and the p-type dopant F4TCNQ (2,3,5,6-tetrafluorotetracyano-1,4-quinodimethane) as an example. Since the HOMO energy level of NPB is close to the LUMO energy level of F4TCNQ, the electrons at the HOMO energy level of NPB can jump to the LUMO energy level of F4TCNQ, forming free holes in the hole transport layer, thereby improving the conductivity of the hole transport layer. In addition, doping will bend the energy band, giving holes the opportunity to be injected in a tunneling manner.

[0081] Strong electron acceptors such as tetracyano-p-benzoquinodimethane (TCNQ) or 2,3,5,6-tetrafluorotetracyano-1,4-benzoquinodimethane (F4TCNQ) are well known, see M. Pfeiffer, A. Beyer, T. Fritz, K. Leo, App. Phys. Lett., 73(22), 3202-3204 (1998) and J. Blochwitz, M. Pfeiffer, T. Fritz, K. Leo, App. Phys. Lett., 73(6), 729-731 (1998). Due to the defects of TCNQ and F4TCNQ in specific applications (molecular weight is too small, volatility is too strong), some more preferred p-type doping materials (disclosed in patents such as DE102013205093A1, WO2009003455A1, CN101330129B, etc.) can be selected from the following:

[0082]

[0083] Wherein: A, E, G are independently selected from O, S, SO2, C(R9R 10 ) or N(R9); M4-M 15 are independently N or CR9; in the general formula T-1, n1 is selected from an integer of 1 to 4; R9-R 22 Each occurrence is independently selected from H, D, F, Cl, CN, NO2, CF3, a perfluoroalkyl group, a sulfone group, a crosslinkable group, or a substituted or unsubstituted aromatic or heteroaromatic ring system having 5 to 40 ring atoms, or an aryloxy or heteroaryloxy group having 5 to 40 ring atoms, or a combination of these groups, wherein one or more of the groups can form a monocyclic or polycyclic aliphatic or aromatic ring system with each other and / or with the ring to which the groups are bonded.

[0084] Some examples of p-type doping materials are disclosed in patents such as TW200629362A, EP2690662A, CN101346830A, DE102013205093A, and CN109912619A. Specific examples of p-type doping materials include:

[0085]

[0086] In certain preferred embodiments, according to the tandem electroluminescent device of the present invention, the p-CGL comprises a compound selected from polymers containing fluorocarbons, polymers containing conductive doping, conductive polymers, such as PEDOT / PSS, PANi; self-assembling monomers, such as compounds containing phosphonic acid and sliane derivatives; metal oxides, such as MoOx, WOx, VOx, etc.

[0087] In a particularly preferred embodiment, the p-CGL comprises a p-type conductive polymer selected from PEDOT / PSS or PANi.

[0088] In a more preferred embodiment, in the tandem electroluminescent device according to the present invention, the p-CGL comprises a hole transport material (HTM).

[0089] Suitable HTM materials may be selected from compounds containing the following structural units: phthalocyanine, porphyrin, amine, aromatic amine, biphenyl triarylamine, thiophene, thiophene, pyrrole, aniline, carbazole, indolizine and their derivatives.

[0090] Preferably, the HTM is selected from cyclic aromatic amine derivative compounds, examples of which include (but are not limited to) the following general structure:

[0091]

[0092] Each Ar 1 -Ar 9 The aromatic hydrocarbon compounds may be independently selected from aromatic hydrocarbon compounds such as benzene, biphenyl, triphenylbenzene, triphenylene, naphthalene, anthracene, phenanthene, phenanthren, fluorene, pyrene, chrysene, perylene, and azulene; aromatic heterocyclic compounds such as dibenzothiophene, dibenzofuran, furan, thiophene, benzofuran, benzothiophene, carbazole, pyrazole, imidazole, triazole, isoxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indolizine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, o-naphthylidene, quinazoline , quinoxaline, naphthalene, phthalide, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, dibenzoselenophene, benzoselenophene, benzofuranpyridine, indolecarbazole, pyridineindole, pyrroledipyridine, furandipyridine, benzothiophenepyridine, thiophenepyridine, benzoselenophenepyridine and selenophenedipyridine; containing groups with 2 to 10 ring structures, which can be the same or different types of cyclic aromatic hydrocarbon groups or aromatic heterocyclic groups, and are directly or through at least one of the following groups linked together, such as oxygen atoms, nitrogen atoms, sulfur atoms, silicon atoms, phosphorus atoms, boron atoms, chain structure units and aliphatic ring groups. Among them, Ar 1 -Ar 9 It may be further substituted, and the substituents may be selected from hydrogen, deuterium, alkyl, alkoxy, amino, alkene, alkyne, aralkyl, heteroalkyl, aryl or heteroaryl.

[0093] In one aspect, Ar 1 -Ar 9 Can be independently selected from the group comprising the following structural units:

[0094]

[0095] Each occurrence of Y is independently selected from C(R0) 2 or NR0 or O or S; X, when it occurs each time, is independently selected from CR0 or N; R0, when it occurs each time, is independently selected from the following groups: hydrogen, deuterium, halogen atoms (F, Cl, Br, I), cyano, alkyl, alkoxy, amino, alkenyl, alkynyl, aralkyl, heteroalkyl, aryl and heteroaryl, and n2 is selected from an integer of 1 to 20.

[0096] Other examples of cyclic aromatic amine derivative compounds can be found in US Pat. Nos. 3,567,450, 4,720,432, 5,061,569, 3,615,404 and 5,061,569.

[0097] Examples of metal complexes that can be used as HTMs include, but are not limited to, the following general structure:

[0098]

[0099] M2 is a metal with an atomic weight greater than 40; (Y 1 -Y 2 ) is a didentate ligand, Y 1 and Y 2 is independently selected from C, N, O, P or S; L 0 is an auxiliary ligand; u is an integer ranging from 1 to the maximum coordination number of this metal.

[0100] In some embodiments, (Y 1 -Y 2 ) is a 2-phenylpyridine derivative.

[0101] In other embodiments, (Y 1 -Y 2 ) is a carbene ligand.

[0102] In other embodiments, M2 is selected from Ir, Pt, Os or Zn.

[0103] In other embodiments, the HOMO of the metal complex is greater than -5.5 eV (relative to vacuum level).

[0104] Examples of suitable HTM compounds are listed below:

[0105]

[0106]

[0107] In certain preferred embodiments, in the tandem electroluminescent device according to the present invention, at least one of the electroluminescent units comprises a functional layer, and the functional layer is selected from a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer, and an electron injection layer. Suitable materials for each functional layer are well known to those skilled in the art.

[0108] In certain preferred embodiments, the hole injection layer or hole transport layer or electron blocking layer comprises an HTM material as described above or below.

[0109] In some other preferred embodiments, the hole blocking layer or the electron transport layer or the electron injection layer comprises an ETM material as described above or below.

[0110] In some preferred embodiments, at least one of the electroluminescent units comprises an organic light-emitting layer; more preferably, each of the electroluminescent units comprises an organic light-emitting layer, ie, a tandem OLED.

[0111] In some preferred embodiments, in the tandem electroluminescent device according to the present invention, the organic light-emitting layer comprises a small molecule material.

[0112] In some embodiments, the organic light-emitting layer comprises a small molecule fluorescent host material and a small molecule fluorescent guest material.

[0113] In some embodiments, the organic light-emitting layer comprises a small molecule phosphorescent host material and a small molecule phosphorescent guest material.

[0114] In some preferred embodiments, the tandem electroluminescent device according to the present invention comprises two electroluminescent units, namely the first electroluminescent unit or the second electroluminescent unit. Figure 1 The structure shown comprises, in sequence, an anode 3, a first electroluminescent unit 1, an n-CGL (n-type charge generation layer) 4, a p-CGL (p-type charge generation layer) 5, a second electroluminescent unit 2 and a cathode 6, wherein the first electroluminescent unit 1 comprises HIL1 (first hole injection layer) 1-1, HTL1 (first hole transport layer) 1-2, EML1 (first light-emitting layer) 1-3 and ETL1 (first electron transport layer) 1-4, and the second electroluminescent unit 2 comprises HTL2 (second hole transport layer) 2-1, EML2 (second light-emitting layer) 2-2 and ETL2 (second electron transport layer) 2-3.

[0115] The phosphorescent host material (also called triplet host material), the fluorescent host material (also called singlet host material), the fluorescent guest material (also called singlet light emitter) and the phosphorescent guest material (also called triplet light emitter) are described in detail below.

[0116] 1. Triplet host material

[0117] Examples of triplet host materials are not particularly limited, and any metal complex or organic compound may be used as a host as long as its triplet energy level is higher than that of a light emitter, particularly a triplet light emitter or a phosphorescent light emitter.

[0118] Examples of metal complexes that can be used as triplet hosts include, but are not limited to, the following general structures:

[0119]

[0120] M3 is a metal; (Y 3 -Y 4 ) is a didentate ligand, Y 3 and Y 4 is independently selected from C, N, O, P or S; L' is an auxiliary ligand; v is an integer ranging from 1 to the maximum coordination number of the metal. In a preferred embodiment, the metal complex that can be used as a triplet host has the following form:

[0121]

[0122] (ON) is a bidentate ligand in which the metal is coordinated to the O and N atoms; L' is an ancillary ligand; v is an integer ranging from 1 to the maximum coordination number of the metal.

[0123] In some embodiments, M3 can be selected from Ir and Pt.

[0124] Examples of organic compounds that can serve as triplet hosts are selected from compounds containing cyclic aromatic hydrocarbon groups, such as benzene, biphenyl, triphenylbenzene, benzofluorene; compounds containing aromatic heterocyclic groups, such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, dibenzocarbazole, indolecarbazole, pyridineindole, pyrroledipyridine, pyrazole, imidazole, triazoles, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazines, oxazines, oxathiazines, oxadiazines, indoles, benzimidazoles, indazoles, oxazoles, diphenyl oxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, o-naphthyridine, quinazoline, quinoxaline, naphthalene, phthalein, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuran pyridine, furopyridine, benzothiophene pyridine, thiophene pyridine, benzoselenophene pyridine and selenophene benzodipyridine; groups containing 2 to 10 ring structures, which can be the same or different types of cyclic aromatic hydrocarbon groups or aromatic heterocyclic groups, and are directly or through at least one of the following groups linked together, such as oxygen atoms, nitrogen atoms, sulfur atoms, silicon atoms, phosphorus atoms, boron atoms, chain structure units and aliphatic ring groups. Wherein, each Ar can be further substituted, and the substituent can be selected from hydrogen, deuterium, cyano, halogen, alkyl, alkoxy, amino, alkene, alkyne, aralkyl, heteroalkyl, aryl or heteroaryl.

[0125] In some preferred embodiments, the triplet host material may be selected from compounds comprising at least one of the following groups:

[0126]

[0127] Wherein: when Y0 appears multiple times, Y0 is independently selected from C(R1)2 or NR1 or O or S; when X0 appears multiple times, X0 is independently selected from CR1 or N, Ar1-Ar3 are selected from aromatic groups or heteroaromatic groups, R1 can be selected from the following groups: hydrogen, deuterium, halogen atoms (F, Cl, Br, I), cyano, alkyl, alkoxy, amino, alkenyl, alkynyl, aralkyl, heteroalkyl, aryl and heteroaryl, and n3 is selected from an integer of 1 to 20.

[0128] Examples of suitable triplet host materials are listed below but are not limited to:

[0129]

[0130]

[0131] 2. Singlet host material

[0132] Examples of the singlet host material are not particularly limited, and any organic compound may be used as a host as long as its singlet energy is higher than that of a light emitter, particularly a singlet light emitter or a fluorescent light emitter.

[0133] Examples of organic compounds used as singlet host materials may be selected from aromatic hydrocarbon compounds containing rings, such as benzene, biphenyl, triphenylbenzene, triphenylene, naphthalene, anthracene, phenanthrene, phenanthrene, fluorene, pyrene, chrysene, perylene, and azulene; aromatic heterocyclic compounds, such as dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolecarbazole, pyridineindole, pyrroledipyridine, pyrazole, imidazole, triazole, isoxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole , indolizine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthalene, phthalide, pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine, benzofuran pyridine, furan dipyridine, benzothiophene pyridine, thiophene dipyridine, benzoselenophene pyridine and selenophene dipyridine; groups containing 2 to 10 ring structures, which may be cyclic aromatic hydrocarbon groups or aromatic heterocyclic groups of the same or different types, and are linked to each other directly or through at least one of the following groups, such as oxygen atoms, nitrogen atoms, sulfur atoms, silicon atoms, phosphorus atoms, boron atoms, chain structural units and aliphatic ring groups.

[0134] In a preferred embodiment, the singlet host material may be selected from compounds comprising at least one of the following groups:

[0135]

[0136] Each time Y4 appears, it is independently selected from C(R2)2 or NR2 or O or S; each time X4 appears, it is independently selected from CR2 or N, each time R2 appears, it is independently selected from the following groups: hydrogen, deuterium, halogen atoms (F, Cl, Br, I), cyano, alkyl, alkoxy, amino, alkenyl, alkynyl, aralkyl, heteroalkyl, aryl and heteroaryl, and n4 is selected from an integer from 1 to 20.

[0137] In some preferred embodiments, the singlet host is selected from derivatives of anthracene, as disclosed in patent documents such as CN102224614B, CN100471827C, CN1914293B, WO2015033559A1, US2014246657A1, WO2016117848A1, WO2016117861A1, WO2016171429A2, CN102369256B, and CN102428158B.

[0138] Some examples of anthracene-based singlet host materials are listed below:

[0139]

[0140] In some more preferred embodiments, the anthracene-based singlet host material is deuterated, that is, the host material molecule contains at least one deuterium atom. Such examples are disclosed in patent documents such as CN102369256B, CN102428158B, CN102639671B, and US2015021586A1. Specific examples are:

[0141]

[0142] 3. Singlet luminophore

[0143] Singlet emitters often have longer conjugated π electron systems. To date, there have been many examples, such as styrylamine and its derivatives disclosed in JP2913116B and WO2001021729A1, indenofluorene and its derivatives disclosed in WO2008 / 006449 and WO2007 / 140847, and triarylamine derivatives of pyrene disclosed in US7233019 and KR20060006760.

[0144] In a preferred embodiment, the singlet emitter can be selected from monostyrylamine, distyrylamine, tristyrylamine, tetrastyrylamine, styrylphosphine, styrylether or aromatic amine.

[0145] A monostyrylamine is a compound comprising an unsubstituted or substituted styryl group and at least one amine, preferably an aromatic amine. A distyrylamine is a compound comprising two unsubstituted or substituted styryl groups and at least one amine, preferably an aromatic amine. A tert-styrylamine is a compound comprising three unsubstituted or substituted styryl groups and at least one amine, preferably an aromatic amine. A tetrastyrylamine is a compound comprising four unsubstituted or substituted styryl groups and at least one amine, preferably an aromatic amine. A preferred styrene is diphenylethylene, which may be further substituted. The corresponding phosphines and ethers are defined similarly to the amines. An arylamine or aromatic amine is a compound comprising three unsubstituted or substituted aromatic or heterocyclic ring systems directly attached to the nitrogen. At least one of these aromatic or heterocyclic ring systems is preferably a fused ring system and preferably has at least 14 aromatic ring atoms. Preferred examples are aromatic anthraceneamines, aromatic anthracene diamines, aromatic pyrene amines, aromatic pyrene diamines, aromatic chrysene amines and aromatic chrysene diamines. An aromatic anthraceneamine is a compound wherein one diarylamine group is directly attached to anthracene, preferably at the 9 position. An aromatic anthracenediamine is a compound wherein two diarylamine groups are directly attached to anthracene, preferably at the 9,10 positions. Aromatic pyreneamines, aromatic pyrenediamines, aromatic chryseneamines and aromatic chrysenediamines are similarly defined, wherein the diarylamine groups are preferably attached to the 1 or 1,6 positions of pyrene.

[0146] Examples of singlet emitters based on vinylamine and aromatic amine, which are also preferred examples, can be found in the following patent documents: WO2006 / 000388, W2006 / 058737, WO2006 / 000389, WO2007 / 065549, WO2007 / 115610, US7250532B2, DE102005058557A1, CN1583691A, JP08053397A, US6251531B1, US2006 / 210830A, EP1957606A1 and US2008 / 0113101A1, and all the contents of the above-listed patent documents are hereby incorporated herein by reference.

[0147] Examples of singlet emitters based on stilbene and its derivatives are disclosed in US Pat. No. 5,121,029.

[0148] Further preferred singlet emitters can be selected from indenofluorene-amines and indenofluorene-diamines, as disclosed in WO2006 / 122630; benzoindenofluorene-amines and benzoindenofluorene-diamines, as disclosed in WO2008 / 006449; dibenzoindenofluorene-amines and dibenzoindenofluorene-diamines, as disclosed in WO2007 / 140847.

[0149] Further preferred singlet emitters can be selected from fluorene-based fused ring systems, such as those disclosed in US2015333277A1, US2016099411A1, and US2016204355A1.

[0150] More preferred singlet emitters can be selected from derivatives of pyrene, such as the structure disclosed in US2013175509A1; triarylamine derivatives of pyrene, such as the triarylamine derivatives of pyrene containing dibenzofuran units disclosed in CN102232068B; other triarylamine derivatives of pyrene with specific structures, such as those disclosed in CN105085334A and CN105037173A. Other materials that can be used as singlet emitters include polycyclic aromatic hydrocarbon compounds, especially derivatives of the following compounds: anthracenes such as 9,10-di(2-naphtho)anthracene, naphthalene, tetracene, xanthene, phenanthrene, pyrene (such as 2,5,8,11-tetra-t-butylperylene), indenopyrene, benzo-fused rings such as (4,4'-bis(9-ethyl-3-carbazole vinyl)-1,1'-biphenyl), diindenopyrene, decacyclic olefins, hexabenzophenone, fluorene, spirobifluorene, arylpyrene (such as US20060222886), arylenevinylene (such as US5121 029, US5130603), cyclopentadiene such as tetraphenylcyclopentadiene, rubrene, coumarin, rhodamine, quinacridone, pyran such as 4 (dicyanomethylene) -6- (4-dimethylaminophenylvinyl-2-methyl) -4H-pyran (DCM), thiopyran, bis (azinyl) imine boron compounds (US2007 / 0092753A1), bis (azinyl) methylene compounds, carbostyryl compounds, oxazinones, benzoxazoles, benzothiazoles, benzimidazoles and dione pyrrolopyrroles. Some materials of singlet emitters can be found in the following patent documents: US20070252517A1, US4769292, US6020078. The entire contents of the above-listed patent documents are hereby incorporated herein by reference.

[0151] Some examples of suitable singlet emitters are listed below:

[0152]

[0153] 4. Triplet emitters

[0154] A triplet emitter is also called a phosphorescent emitter. In a preferred embodiment, the triplet emitter is a phosphorescent emitter having the general formula M(L)n 1 A metal complex of the invention, wherein M is a metal atom, L may be the same or different each time it occurs, and is an organic ligand which is bonded or coordinated to the metal atom M through one or more positions, and n 1 is an integer between 1 and 6. Preferably, the triplet luminophore contains a chelating ligand, i.e., a ligand that coordinates to the metal through at least two binding points, and it is particularly preferred that the triplet luminophore contains two or three identical or different bidentate or multidentate ligands. Chelating ligands are beneficial to improve the stability of the metal complex. In a preferred embodiment, the metal complex that can be used as a triplet luminophore has the following form:

[0155]

[0156] The metal atom M4 is selected from transition metal elements, lanthanides or actinides, preferably Ir, Pt, Pd, Au, Rh, Ru, Os, Re, Cu, Ag, Ni, Co, W or Eu, especially preferably Ir, Au, Pt, W or Os.

[0157] Ar4 and Ar5 may be the same or different each time they appear, and are a cyclic group, wherein Ar4 contains at least one donor atom, that is, an atom with a lone pair of electrons, such as nitrogen, through which the cyclic group is coordinated and connected to the metal; wherein Ar5 contains at least one carbon atom, through which the cyclic group is connected to the metal; Ar4 and Ar5 are linked together by covalent bonds, and may each carry one or more substituent groups, and they may also be linked together by substituent groups; L" may be the same or different each time it appears, and is a bidentate chelating auxiliary ligand, preferably a monoanionic bidentate chelating ligand; q1 may be 0, 1, 2 or 3, preferably 2 or 3; q2 may be 0, 1, 2 or 3, preferably 1 or 0. Examples of organic ligands may be selected from phenylpyridine derivatives or 7,8-benzoquinoline derivatives. All of these organic ligands may be substituted, for example, by alkyl chains or fluorine or silicon. The auxiliary ligand may be preferably selected from acetic acid acetone or picric acid.

[0158] Examples of some triplet emitter materials and their applications can be found in the following patent documents and literature: WO200070655, WO200141512, WO200202714, WO200215645, WO2005033244, WO2005019373, US20050258742, US20070087219, US20070252517, US2008027220, WO2009146770, US2009 0061681, WO2009118087, WO2010015307, WO2010054731, WO2011157339, WO2012007087, WO201200708, WO201 3107487, WO2013094620, WO2013174471, WO2014031977, WO2014112450, WO2014007565, WO2014024131, Baldo et al. Nature (2000), 750, Adachi et al. Appl. Phys. Lett. (2001), 1622, Kido et al. Appl. Phys. Lett. (1994), 2124, Wrighton et al. J. Am. Chem. Soc. (1974), 998, Ma et al. Synth. Metals (1998), 245. The entire contents of the above-listed patent documents and literature are hereby incorporated by reference.

[0159] Some examples of suitable triplet emitters are listed below:

[0160]

[0161] In some other embodiments, in the tandem OLED according to the present invention, the organic light-emitting layer comprises a polymer.

[0162] In some embodiments, the organic functional materials described above, including HIM, HTM, ETM, EIM, host materials, fluorescent light emitters, and phosphorescent light emitters may be in the form of polymers.

[0163] In a preferred embodiment, the polymer suitable for the present invention is a conjugated polymer. Generally, the conjugated polymer has a structure shown in the following general formula (III):

[0164]

[0165] Among them, A1 to A n In case of multiple occurrences the structural unit may be independently selected to be identical or different.

[0166] A1: A π-conjugated structural unit with a large energy gap, also known as a backbone unit, selected from monocyclic or polycyclic aromatic or heteroaromatic groups, and the preferred unit form is benzene, biphenylene, naphthalene, anthracene, phenanthrene, dihydrophenanthrene, 9,10-dihydrophenanthrene, fluorene, difluorene, spirobifluorene, p-phenylenevinylene, trans-indenofluorene, cis-indeno, dibenzo-indenofluorene, indenonaphthalene and their derivatives.

[0167] A2 to A n : A conjugated structural unit with a small energy gap, also called a functional unit, can be selected from the structural units containing the hole injection or transport material (HIM / HTM), hole blocking material (HBM), electron injection or transport material (EIM / ETM), electron blocking material (EBM), organic host material (Host), singlet luminophore (fluorescent luminophore), triplet luminophore (phosphorescent luminophore) mentioned above according to different functional requirements. Or it can be a functional group that can make the molecule cross-linked or branched, which can be selected from a monomer containing three or more reactive functional groups, and at least have three sites of bonding with the main chain of the polymer. Or it can be other structural units with specific functions.

[0168] X1 to X n : The mol% of the repeating unit is greater than 0, and X1+X2+X3…X n =1.

[0169] In a preferred embodiment, the high polymer HTM material is a homopolymer, and the preferred homopolymer is selected from polythiophene, polypyrrole, polyaniline, polybiphenyl triarylamine, polyvinyl carbazole and their derivatives.

[0170] In another preferred embodiment, the polymer HTM material is a conjugated binary copolymer represented by the general formula (III), wherein:

[0171] A2: A functional group having hole transporting ability can be selected from the structural unit comprising the hole injection or transport material (HIM / HTM) described above; in a preferred embodiment, A2 is selected from amines, biphenyl triarylamines, thiophene, thiophene, pyrrole, aniline, carbazole, indolecarbazole, indolizine, pentacene, phthalocyanine, porphyrin and their derivatives.

[0172] X1, X2: mol% of repeating units, X1>0, X2>0, and X1+X2=1; usually X2≥0.10, preferably ≥0.15, more preferably ≥0.20, and most preferably X1=X2=0.5.

[0173] Another preferred class of organic ETM materials is polymers with electron transport capabilities, including conjugated polymers and non-conjugated polymers.

[0174] The preferred high polymer ETM material is a homopolymer, and the preferred homopolymer is selected from polyphenanthrene, polyphenanthroline, polyindenofluorene, polyspirobifluorene, polyfluorene and their derivatives.

[0175] Another preferred polymer ETM material is a conjugated binary copolymer represented by the general formula (III), wherein A2 can be independently selected to be the same or different when it appears multiple times.

[0176] A2: A functional group having electron transport capability is preferably selected from tri(8-hydroxyquinoline)aluminum (AlQ3), benzene, biphenylene, naphthalene, anthracene, phenanthrene, dihydrophenanthrene, fluorene, difluorene, spirobifluorene, p-phenylenevinylene, pyrene, perylene, 9,10-dihydrophenanthrene, phenazine, phenanthroline, trans-indenofluorene, cis-indeno, dibenzo-indenofluorene, indenonaphthalene, benzanthracene and their derivatives.

[0177] X1, X2: mol% of repeating units, X1>0, X2>0, and X1+X2=1; usually X2≥0.10, preferably ≥0.15, more preferably ≥0.20, and most preferably X1=X2=0.5.

[0178] In another preferred embodiment, the light-emitting polymer material is a conjugated terpolymer represented by the general formula (III), wherein:

[0179] A2: The functional group having hole or electron transporting ability can be selected from the structural units comprising the hole injection or transport material (HIM / HTM) or the electron injection or transport material (EIM / ETM) mentioned above.

[0180] A3: A group having a light-emitting function can be selected from structural units including the singlet light emitter (fluorescent light emitter) and triplet light emitter (phosphorescent light emitter) mentioned above.

[0181] X1, X2, X3: mol% of repeating units, X1>0, X2>0, X3>0, and X1+X2+X3=1; in certain preferred embodiments, X1=X2=X3.

[0182] Examples of luminescent polymers are disclosed in the following patent applications: WO2007043495, WO2006118345, WO2006114364, WO2006062226, WO2006052457, WO2005104264, WO2005056633, WO2005033174, WO2004113412, WO2004041901, WO200 3099901, WO2003051092, WO2003020790, US2020040076853, US2020040002576, US2007208567, US2005962631, EP201345477, EP2001344788, DE102004020298, all the contents of the above patent documents are hereby incorporated into this document for reference.

[0183] In another preferred embodiment, the cross-linkable or branched polymer material is a conjugated terpolymer represented by the general formula (III), wherein:

[0184] A2: A conjugated structural unit with a small energy gap, also called a functional unit (Functional Unit), can be selected from the structural units comprising the hole injection or transport material (HIM / HTM), hole blocking material (HBM), electron injection or transport material (EIM / ETM), electron blocking material (EBM), organic host material (Host), singlet light emitter (fluorescent light emitter), triplet light emitter (phosphorescent light emitter) mentioned above according to different functional requirements.

[0185] A3: It has a functional group that can crosslink or branch the molecule, which can be selected from monomers containing three or more reactive functional groups, and has at least three bonding sites with the polymer main chain.

[0186] X1, X2, X3: mol% of repeating units, X1>0, X2>0, X3>0, and X1+X2+X3=1; in certain preferred embodiments, X1=X2=X3.

[0187] In another embodiment, the polymer suitable for the present invention is a non-conjugated polymer. This can be a polymer in which all functional groups are on the side chain, and the main chain is a non-conjugated polymer. Some non-conjugated polymers used as phosphorescent main body or phosphorescent luminescent material are disclosed in patent applications such as US7250226B2, JP2007059939A, JP2007211243A2 and JP2007197574A2. Some non-conjugated polymers used as fluorescent luminescent material are disclosed in patent applications such as JP2005108556, JP2005285661 and JP2003338375. In addition, a non-conjugated polymer can also be a polymer, and the conjugated functional units on the main chain are linked by non-conjugated linking units, and the example of this polymer is disclosed in DE102009023154.4 and DE102009023156.0. The entire contents of the above patent documents are hereby incorporated by reference.

[0188] In another preferred embodiment, at least one of the electroluminescent units comprises a quantum dot light-emitting layer. The quantum dot light-emitting layer comprises a light-emitting quantum dot. More preferably, each of the electroluminescent units comprises a quantum dot light-emitting layer, i.e., a tandem QLED.

[0189] The semiconductor that forms the light-emitting quantum dots may include a Group IV element, a group of Group II-VI compounds, a group of Group II-V compounds, a group of Group III-VI compounds, a group of Group III-V compounds, a group of Group IV-VI compounds, a group of Group I-III-VI compounds, a group of Group II-IV-VI compounds, a group of Group II-IV-V compounds, an alloy comprising any of the above, and / or a mixture of the above compounds, including a ternary or quaternary mixture or alloy. A non-limiting list of examples includes zinc oxide, zinc sulfide, zinc selenide, zinc telluride, cadmium oxide, cadmium sulfide, cadmium selenide, cadmium telluride, magnesium sulfide, magnesium selenide, gallium arsenide, gallium nitride, gallium phosphide, gallium selenide, gallium antimonide, mercuric oxide, mercury sulfide, mercury selenide, mercury telluride, indium arsenide, indium nitride, indium phosphide, indium antimonide, aluminum arsenide, aluminum nitride, aluminum phosphide, aluminum antimonide, titanium nitride, titanium phosphide, titanium arsenide, titanium antimonide, lead oxide, lead sulfide, lead selenide, lead telluride, germanium, silicon, an alloy comprising any of the foregoing, and / or a mixture comprising any of the foregoing, including ternary, quaternary mixtures or alloys.

[0190] In a very preferred embodiment, the luminescent quantum dot comprises a II-VI semiconductor material, preferably selected from CdSe, CdS, CdTe, ZnO, ZnSe, ZnS, ZnTe, HgS, HgSe, HgTe, CdZnSe and any combination thereof. In a suitable embodiment, the CdSe material is used as a nano-luminescent material for visible light due to its relatively mature synthesis.

[0191] In another preferred embodiment, the light-emitting quantum dots comprise III-V semiconductor materials, preferably selected from InAs, InP, InN, GaN, InSb, InAsP, InGaAs, GaAs, GaP, GaSb, AlP, AlN, AlAs, AlSb, CdSeTe, ZnCdSe and any combination thereof.

[0192] In another preferred embodiment, the light-emitting quantum dots contain IV-VI semiconductor materials, preferably selected from PbSe, PbTe, PbS, PbSnTe, Tl2SnTe5 and any combination thereof.

[0193] The relevant luminescent quantum dots and electroluminescent devices containing luminescent quantum dots are disclosed in Chinese patent CN102916097A. The entire contents of the above patent documents are hereby incorporated herein by reference.

[0194] The present invention also relates to a method for preparing a tandem electroluminescent device, wherein an anode, a first electroluminescent unit, an n-type charge generation layer (n-CGL), a second electroluminescent unit and a cathode are sequentially deposited on a substrate, wherein the method for preparing the n-CGL is as follows:

[0195] 1) co-evaporating an n-type organic semiconductor material and a bimetallic sandwich compound onto a first electroluminescent unit by vacuum thermal evaporation to form a solid film, wherein the bimetallic sandwich compound comprises a structure represented by one of the following general formulae (II-1) to (II-3); or dispersing or dissolving the n-type organic semiconductor material and the bimetallic sandwich compound in an organic solvent to form a liquid solution or dispersion, then coating the liquid solution or dispersion onto the first electroluminescent unit, and removing the organic solvent to form a solid film;

[0196]

[0197] Where: M 1 、M 2 、M 3 , x1, x2, y1, y2, R 1 , R 2 , R d The definition of is as above.

[0198] 2) A redox reaction occurs in the solid film, causing at least a portion of the n-type organic semiconductor material to gain electrons, and the bimetallic sandwich compound to lose electrons to form two metal interlayer cations, and the two metal interlayer cations are respectively selected from the structures shown in one of the general formulas (I-1) to (I-3).

[0199] In a preferred embodiment, the bimetallic sandwich compound is selected from one of the following structural formulas:

[0200]

[0201]

[0202]

[0203] Among them, Me4 represents 4 methyl substitutions, Me5 represents 5 methyl substitutions, and Me6 represents 6 methyl substitutions.

[0204] The synthesis method of the bimetallic sandwich compounds according to the general formula (II-1) to (II-3) is as follows:

[0205] 1. Synthesis of n-dopant1:

[0206]

[0207] Step 1: Synthesis of Ruthenium PF6:[C5(CH3)5Ru(η 6 -C6H6)][PF6]

[0208] 1g of phenylruthenium dichloride ([(C6H6)RuCl2]2) was dissolved in 100mL of acetonitrile under nitrogen protection, and then 2mL (3.4mmol) (n-Bu)3Sn(C5(CH3)5) was added, and then heated to reflux for 18.5 hours, and the solvent was removed by rotary evaporation to leave a dark oily substance. After adding 500mL of distilled water, it was filtered to obtain a light yellow filtrate. Excessive NH4PF6 was added to precipitate the product. After filtration, the filter cake was passed through an alumina column and recrystallized (acetone / ether = 5:1) to obtain [C5(CH3)5Ru(η 6 -C6H6)][PF6].

[0209] Step 2: Synthesis of Ruthenium Dimer: [(C5(CH3)5Ru)(η 5 -C6H6:η 5 -C6H6)Ru(C5(CH3)5)]

[0210] Under nitrogen protection, 0.5 mg of Na and Hg alloy powder was dissolved in 50 mL of tetrahydrofuran, and 200 mg of [(C5(CH3)5Ru)(η 6 -C6H6)][PF6](0.51mmol) in anhydrous THF solution, stirred at room temperature for 2 hours, the solvent and volatile components were distilled off under reduced pressure to obtain a solid residue, which was extracted with anhydrous toluene, toluene was removed by distillation under reduced pressure, and washed with pentane, and dried under vacuum to obtain 60mg of n-dopant1 with a yield of 30% [(C5(CH3)5Ru)(η 5 -C6H6:η 5 -C6H6)Ru(η 5 -C5(CH3)5)](Ruthenium Dimer).

[0211] 2. Synthesis of n-dopant2:

[0212]

[0213] Step 1: Synthesis of Rhodium PF6:[η 5 -C5H5Rh(η 5 -C5H5)][PF6]

[0214] 1g phenyl rhodium dichloride ([(C5H5)RhCl2]2) was dissolved in 100mL acetonitrile under nitrogen protection, and then 2mL (3.4mmol) (n-Bu)3Sn (C5H5) was added and then heated to reflux for 18.5 hours. The solvent was removed by rotary evaporation to leave a dark oil. After adding 500mL of distilled water, it was filtered to obtain a light yellow filtrate. Excessive NH4PF6 was added to precipitate the product. After filtering, the filter cake was passed through an alumina column and recrystallized (acetone / ether = 5:1) to obtain [η 5 -C5H5Rh(η 5 -C5H5)][PF6].

[0215] Step 2: Synthesis of Rhodium Dimer: [(η 5 -C5H5Rh)(η 4 -C5H5:η 4 -C5H5)Rh(η 5 -C5H5)]

[0216] Under nitrogen protection, 0.5 mg Na and Hg alloy powders were dissolved in 50 mL tetrahydrofuran, and 200 mg [η 5 -C5H5Rh(η 5-C5H5)][PF6](0.51mmol) in anhydrous THF solution, stirred at room temperature for 2 hours, the solvent and volatile components were distilled off under reduced pressure to obtain a solid residue, which was extracted with anhydrous toluene, toluene was removed by distillation under reduced pressure, and washed with pentane, and dried under vacuum to obtain 20mg of n-dopant2, with a yield of 10% [(η 5 -C5H5Rh)(η 4 -C5H5:η 4 -C5H5)Rh(η 5 -C5H5)].

[0217] 3. Synthesis of n-dopant3:

[0218]

[0219] Step 1: Synthesis of Rhenium PF6:[C6(CH3)6Re(η 6 -C6H6)][PF6]

[0220] 1g of phenylrhenium dichloride ([(C6H6)ReCl2]2) was dissolved in 100mL of acetonitrile under nitrogen protection, and then 2mL (3.4mmol) (n-Bu)3Sn (C6H6) was added and then heated to reflux for 18.5 hours. The solvent was removed by rotary evaporation to leave a dark oil. After adding 500ml of distilled water, it was filtered to obtain a light yellow filtrate. Excessive NH4PF6 was added to precipitate the product. After filtration, the filter cake was passed through an alumina column and recrystallized (acetone / ether = 5:1) to obtain [(η 6 -C6H6Re(η 6 -C6H6)][PF6].

[0221] [(η 6 -C6H6Re(η 6 -C6H6)][PF6] (0.26 g) was dissolved in 150 ml of acetonitrile, and the solution was added to a quartz water-jacketed electrolytic cell. The electrolytic cell was plugged and nitrogen was bubbled for 1.5 hours. The solution was stirred and irradiated with a 400 W medium-pressure mercury lamp for 20 hours. After the reaction was completed, the solution was transferred to a conical flask and the solvent was evaporated and dried to obtain a golden yellow product [(η 6 -C6H6Re(CH3CN)3)][PF6] total 0.25g.

[0222] 60 mg [(η 6 -C6H6Re(CH3CN)3)][PF6] was added to 2mL 6-methylbenzene and 15mL dichloroethane, stirred for 18h and refluxed for 2h. The mixed solution was passed through an alumina column and then dried to obtain 40mg [C6(CH3)6Re(η 6 -C6H6)][PF6].

[0223] Step 2: Synthesis of Rhenium Dimer: [(C6(CH3)6Re)(η 5 -C6H6:η 5 -C6H6)Re(η 5 -C6(CH3)6)]

[0224] Under nitrogen protection, 0.5 mg Na and Hg alloy powders were dissolved in 50 mL tetrahydrofuran, and 200 mg [C6(CH3)6Re(η 6 -C6H6)][PF6](0.51mmol) in anhydrous THF solution, stirred at room temperature for 2 hours, the solvent and volatile components were distilled off under reduced pressure to obtain a solid residue, which was extracted with anhydrous toluene, toluene was removed by distillation under reduced pressure, and washed with pentane, and dried under vacuum to obtain n-dopant3 (10mg in total) with a yield of 5% [(C6(CH3)6Re)(η 5 -C6H6:η 5 -C6H6)Re(η 5 -C6(CH3)6)].

[0225] 4. Synthesis of n-dopant4:

[0226]

[0227] Step 1: Synthesis of Ferrum PF6:[C5(CH3)5Fe(η 6 -C6H6)][PF6]

[0228] For synthesis, see (Inorg. Chem. 1986, 25, 3501-3504).

[0229] Step 2: Synthesis of Ferrum Dimer: [(C5(CH3)5Fe)(η 5 -C6H6:η 5 -C6H6)Fe(C5(CH3)5)]

[0230] Under nitrogen protection, 0.5 mg of Na and Hg alloy powder was dissolved in 50 mL of tetrahydrofuran, and 200 mg of [(C5(CH3)5Fe)(η 6 -C6H6)][PF6](0.51mmol) in anhydrous THF solution, stirred at room temperature for 2 hours, the solvent and volatile components were distilled off under reduced pressure to obtain a solid residue, which was extracted with anhydrous toluene, toluene was removed by distillation under reduced pressure, and washed with pentane, and dried under vacuum to obtain 60mg of n-dopant4 with a yield of 30% [(C5(CH3)5Fe)(η 5 -C6H6:η5 -C6H6)Fe(C5(CH3)5)](Ferrum Dimer).

[0231] 5. Synthesis of n-dopant5:

[0232]

[0233] Step 1: Synthesis of Osmium PF6:[C5(CH3)5Os(η 6 -C6H6)][PF6]

[0234] The synthesis method is similar to that of n-dopant5, and can be synthesized according to the literature (Inorg. Chem. 1986, 25, 3501-3504).

[0235] Step 2: Synthesis of OsmiumDimer: [(C5(CH3)5Os)(η 5 -C6H6:η 5 -C6H6)Os(C5(CH3)5)]

[0236] Under nitrogen protection, 0.5 mg Na and Hg alloy powders were dissolved in 50 mL tetrahydrofuran, and 200 mg [C5(CH3)5Os(η 6 -C6H6)][PF6](0.51mmol) in anhydrous THF solution, stirred at room temperature for 2 hours, the solvent and volatile components were distilled off under reduced pressure to obtain a solid residue, which was extracted with anhydrous toluene, toluene was removed by distillation under reduced pressure, and washed with pentane, and dried under vacuum to obtain 4 mg of n-dopant5 with a yield of 2% [(C5(CH3)5Os)(η 5 -C6H6:η 5 -C6H6)Os(C5(CH3)5)](Osmium Dimer).

[0237] 6. Synthesis of n-dopant6:

[0238]

[0239] The synthesis of similar compounds has been reported in the literature, where n-dopant 6 can be obtained by simply replacing 5-methylcyclopentadiene. For the synthesis, see: (Gusev et al, J. Organomet Chem 1997, 531, 95-100).

[0240] 7. Synthesis of n-dopant7:

[0241]

[0242] The synthesis method of n-dopant 7 is similar to that of n-dopant 6, except that the Ir element is replaced by the Co element. For the synthesis, see: (Gusev et al, J. Organomet Chem 1997, 531, 95-100).

[0243] Another object of the present invention is to provide a material solution for printing n-CGL for printed electronics.

[0244] In other embodiments, the solubility of the bimetallic sandwich compounds according to general formula (II-1) to (II-3) in organic solvents (such as toluene) at 25°C is ≥5 mg / mL, preferably ≥8 mg / mL, and most preferably ≥10 mg / mL.

[0245] The present invention further relates to a composition or ink comprising at least one bimetallic sandwich compound as shown in general formula (II-1) to (II-3), and at least one organic solvent, wherein the at least one organic solvent has a boiling point ≥150°C, preferably ≥180°C, and most preferably ≥200°C.

[0246] In a more preferred embodiment, the composition or ink further comprises an ETM material; the ETM material can be selected from small molecules or polymer materials.

[0247] In some other preferred embodiments, the ETM material comprises at least 2 or more cross-linkable groups. In the present invention, "cross-linkable groups" refer to reactive groups that can chemically combine two or more molecules through covalent bonds.

[0248] In a preferred embodiment, according to the composition or ink of the present invention, the crosslinkable group is selected from: 1) linear or cyclic alkenyl or linear diene and alkynyl; 2) alkenyloxy, dieneoxy; 3) acrylic group; 4) propylene oxide and ethylene oxide; 5) silane group; 6) cyclobutane group.

[0249] Preferably, the cross-linkable group is selected from the following structure:

[0250]

[0251] Wherein, the dotted line represents a linking bond; s and t are independently selected from integers greater than or equal to 0; Ar 10 The same or different ones are selected from empty, or aromatic or heteroaromatic groups having 5 to 24 ring atoms; R 101 -R 103 The definition of R is the same as above. 1 .

[0252] In certain more preferred embodiments, the crosslinkable structural unit as described above is selected from the following structural formula:

[0253]

[0254] Among them, R 104 The definition is the same as above; n5 is an integer greater than 0; L 1 represents a single bond or a linking group, and when it represents a linking group, it is an aromatic group or a heteroaromatic group; the dotted bond shown represents a bond to the functional structural unit Ar.

[0255] In some preferred embodiments, L 1 When representing a linker, it is particularly preferred to be selected from the following structures:

[0256]

[0257] When used in printing processes, the viscosity and surface tension of the ink are important parameters. The appropriate surface tension parameters of the ink are suitable for a specific substrate and a specific printing method.

[0258] In a preferred embodiment, the surface tension of the ink according to the present invention at operating temperature or at 25°C is approximately in the range of 19 dyne / cm to 50 dyne / cm; more preferably in the range of 22 dyne / cm to 35 dyne / cm; and most preferably in the range of 25 dyne / cm to 33 dyne / cm.

[0259] In another preferred embodiment, the viscosity of the ink according to the present invention at the working temperature or 25° C. is about 1 cps to 100 cps; preferably 1 cps to 50 cps; more preferably 1.5 cps to 20 cps; and most preferably 4.0 cps to 20 cps. The composition thus formulated will facilitate inkjet printing.

[0260] The viscosity can be adjusted by different methods, such as by the selection of suitable solvents and the concentration of functional materials in the ink. The ink containing the polymer, or the mixture or the conductive polymer according to the present invention can facilitate people to adjust the printing ink in an appropriate range according to the printing method used. Generally, the weight ratio of the functional material contained in the composition according to the present invention is in the range of 0.3wt% to 30wt%, preferably in the range of 0.5wt% to 20wt%, more preferably in the range of 0.5wt% to 15wt%, more preferably in the range of 0.5wt% to 10wt%, and the best is in the range of 1wt% to 5wt%.

[0261] In some embodiments, according to the ink of the present invention, the at least one organic solvent is selected from aromatic or heteroaromatic based solvents, in particular aliphatic chain / ring substituted aromatic solvents, or aromatic ketone solvents, or aromatic ether solvents.

[0262] Examples of organic solvents suitable for the present invention include, but are not limited to: aromatic or heteroaromatic based solvents: p-diisopropylbenzene, pentylbenzene, tetralin, cyclohexylbenzene, chloronaphthalene, 1,4-dimethylnaphthalene, 3-isopropylbiphenyl, p-methylisopropylbenzene, dipentylbenzene, tripentylbenzene, pentyltoluene, o-xylene, m-xylene, p-xylene, o-diethylbenzene, m-diethylbenzene, p-diethylbenzene, 1,2,3,4-tetramethylbenzene, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, butylbenzene, dodecylbenzene, dihexylbenzene, dibutylbenzene, p-diisopropylbenzene, 1-methoxynaphthalene, cyclohexylbenzene, dimethylnaphthalene, 3-isopropylbiphenyl, p-methylisopropylbenzene, 1-methylnaphthalene, 1,2,4-trichlorobenzene , 1,3-dipropoxybenzene, 4,4-difluorodiphenylmethane, 1,2-dimethoxy-4-(1-propenyl)benzene, diphenylmethane, 2-phenylpyridine, 3-phenylpyridine, N-methyldiphenylamine, 4-isopropylbiphenyl, α,α-dichlorodiphenylmethane, 4-(3-phenylpropyl)pyridine, benzyl benzoate, 1,1-bis(3,4-dimethylphenyl)ethane, 2-isopropylnaphthalene, dibenzyl ether, etc.; ketone-based solvents: 1-tetralone, 2-tetralone, 2-(phenylepoxy)tetralone, 6-(methoxy)tetralone, acetophenone, propiophenone, benzophenone, and their derivatives, such as 4-methylacetophenone, 3-methylacetophenone, 2-methylacetophenone, 4 -Methylpropiophenone, 3-methylpropiophenone, 2-methylpropiophenone, isophorone, 2,6,8-trimethyl-4-nonanone, fenchone, 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone, 2,5-hexanedione, phorone, di-n-amyl ketone; aromatic ether solvents: 3-phenoxytoluene, butoxybenzene, benzylbutylbenzene, p-anisaldehyde dimethyl acetal, tetrahydro-2-phenoxy-2H-pyran, 1,2-dimethoxy-4-(1-propenyl)benzene, 1,4-benzodioxane, 1,3-dipropylbenzene, 2,5-dimethoxytoluene, 4-ethylphenyl ether, 1,2,4-trimethoxybenzene, 4-(1-propenyl)-1,2-dimethoxybenzene, 1,3-di Methoxybenzene, glycidyl phenyl ether, dibenzyl ether, 4-tert-butylanisole, trans-p-propenylanisole, 1,2-dimethoxybenzene, 1-methoxynaphthalene, diphenyl ether, 2-phenoxymethyl ether, 2-phenoxytetrahydrofuran, ethyl-2-naphthyl ether, amyl ether, hexyl ether, dioctyl ether, ethylene glycol dibutyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol ethyl methyl ether, triethylene glycol butyl methyl ether, tripropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether; ester solvents: alkyl octanoate, alkyl sebacate, alkyl stearate, alkyl benzoate, alkyl phenylacetate, alkyl cinnamate, alkyl oxalate, alkyl maleate, alkyl lactone, alkyl oleate, etc.

[0263] Further, according to the ink of the present invention, the at least one organic solvent can be selected from: aliphatic ketones, for example, 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone, 2,5-hexanedione, 2,6,8-trimethyl-4-nonanone, phorone, di-n-amyl ketone, etc.; or aliphatic ethers, for example, amyl ether, hexyl ether, dioctyl ether, ethylene glycol dibutyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol ethyl methyl ether, triethylene glycol butyl methyl ether, tripropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, etc.

[0264] In some other embodiments, the printing ink further comprises another organic solvent. Examples of another organic solvent include (but are not limited to): methanol, ethanol, 2-methoxyethanol, dichloromethane, chloroform, chlorobenzene, o-dichlorobenzene, tetrahydrofuran, anisole, morpholine, toluene, o-xylene, m-xylene, p-xylene, 1,4-dioxane, acetone, methyl ethyl ketone, 1,2-dichloroethane, 3-phenoxytoluene, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, ethyl acetate, butyl acetate, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, tetralin, decalin, indene and / or mixtures thereof.

[0265] In a preferred embodiment, the composition according to the present invention is a solution.

[0266] In another preferred embodiment, the composition according to the present invention is a suspension.

[0267] The composition in the embodiment of the present invention may include 0.01wt% to 10wt% of the bimetallic sandwich compound according to the general formula (II-1) to (II-3), preferably 0.1wt% to 9wt%, more preferably 0.2wt% to 8wt%, and most preferably 0.25wt% to 5wt%.

[0268] The present invention also relates to the use of the composition as a coating or printing ink in the preparation of organic electronic devices, and particularly preferably a preparation method by printing or coating.

[0269] Among them, suitable printing or coating techniques include (but are not limited to) inkjet printing, nozzle printing, gravure printing, letterpress printing, screen printing, dip coating, spin coating, doctor blade coating, roller printing, twist roller printing, lithography, flexographic printing, rotary printing, spraying, brushing or pad printing, slit extrusion coating, etc. The preferred ones are inkjet printing, nozzle printing and gravure printing. The solution or suspension may further include one or more components such as surfactant compounds, lubricants, wetting agents, dispersants, hydrophobic agents, adhesives, etc., for adjusting viscosity, film-forming properties, improving adhesion, etc. For detailed information on printing technology and its related requirements for related solutions, such as solvents and concentrations, viscosity, etc., please refer to the "Handbook of Print Media: Technologies and Production Methods" edited by Helmut Kipphan, ISBN 3-540-67326-1.

[0270] In some embodiments, the tandem electroluminescent device according to the present invention comprises, in sequence, an anode, a first electroluminescent unit, an n-CGL, a p-CGL, a second electroluminescent unit, and a cathode.

[0271] In some preferred embodiments, the first electroluminescent unit, n-CGL, p-CGL, and second electroluminescent unit are all obtained by vacuum evaporation.

[0272] In a more preferred embodiment, the first electroluminescent unit is obtained by the above-mentioned printing or coating technology; more preferably, the first electroluminescent unit comprises a cross-linkable main material or a cross-linkable luminescent polymer, which can be cross-linked and cured by heating and / or light after film formation.

[0273] In another preferred embodiment, the second electroluminescent unit is obtained by the above-mentioned printing or coating technology; more preferably, the second electroluminescent unit comprises a cross-linkable main material or a cross-linkable luminescent polymer, which can be cross-linked and cured by heating and / or light after film formation.

[0274] In another more preferred embodiment, the n-CGL is obtained by the above-mentioned printing or coating technology; more preferably, the n-CGL comprises a cross-linkable ETM and a bimetallic sandwich compound as mentioned above, which can be cross-linked, cured and n-type doped by heating and light after film formation.

[0275] In another preferred embodiment, the first electroluminescent unit or the second electroluminescent unit comprises a luminescent quantum dot.

[0276] In the above-mentioned tandem electroluminescent device, it includes a substrate, an anode, and a cathode.

[0277] The substrate can be opaque or transparent. A transparent substrate can be used to make a transparent light-emitting device. For example, see Bulovic et al. Nature 1996, 380, p29, and Gu et al., Appl. Phys. Lett. 1996, 68, p2606. The substrate can be rigid or elastic. The substrate can be plastic, metal, semiconductor wafer or glass. It is best that the substrate has a smooth surface. Substrates without surface defects are particularly ideal. In a preferred embodiment, the substrate is flexible and can be selected from polymer films or plastics, and its glass transition temperature (Tg) is above 150°C, preferably above 200°C, more preferably above 250°C, and preferably above 300°C. Examples of suitable flexible substrates are polyethylene terephthalate (PET) and polyethylene glycol (2,6-naphthalene) (PEN).

[0278] The anode may include a conductive metal or metal oxide, or a p-type conductive polymer. The anode can easily inject holes into the hole injection layer (HIL) or the hole transport layer (HTL) or the light-emitting layer. In one embodiment, the absolute value of the difference between the work function of the anode and the HOMO energy level or valence band energy level of the light-emitting body in the light-emitting layer or the p-type semiconductor material as the HIL or HTL or the electron blocking layer (EBL) is less than 0.5 eV, preferably less than 0.3 eV, and most preferably less than 0.2 eV. Examples of anode materials include, but are not limited to: Al, Cu, Au, Ag, Mg, Fe, Co, Ni, Mn, Pd, Pt, ITO, aluminum-doped zinc oxide (AZO), etc. Other suitable anode materials are known and can be easily selected for use by a person of ordinary skill in the art. The anode material can be deposited using any suitable technique, such as a suitable physical vapor deposition method, including radio frequency magnetron sputtering, vacuum thermal evaporation, electron beam (e-beam), etc. In some embodiments, the anode is patterned. Patterned ITO conductive substrates are commercially available and can be used to prepare devices according to the present invention.

[0279] The cathode may comprise a conductive metal or metal oxide, or an n-type conductive polymer, preferably a conductive polymer according to the present invention. The cathode can easily inject electrons into the EIL or ETL or directly into the light-emitting layer. In one embodiment, the absolute value of the difference between the work function of the cathode and the LUMO energy level or conduction band energy level of the luminophore in the light-emitting layer or the n-type semiconductor material as the electron injection layer (EIL) or the electron transport layer (ETL) or the hole blocking layer (HBL) is less than 0.5 eV, preferably less than 0.3 eV, and most preferably less than 0.2 eV. In principle, all materials that can be used as cathodes of OLEDs may be used as cathode materials for the device of the present invention. Examples of cathode materials include, but are not limited to, Al, Au, Ag, Ca, Ba, Mg, LiF / Al, MgAg alloy, BaF2 / Al, Cu, Fe, Co, Ni, Mn, Pd, Pt, ITO, etc. The cathode material can be deposited using any suitable technique, such as a suitable physical vapor deposition method, including radio frequency magnetron sputtering, vacuum thermal evaporation, electron beam (e-beam), etc.

[0280] The tandem electroluminescent device according to the present invention may further comprise other functional layers, such as a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer (EBL), an electron injection layer (EIL), an electron transport layer (ETL), and a hole blocking layer (HBL). Materials suitable for use in these functional layers are described in detail above and in WO2010135519A1, US20090134784A1, and WO2011110277A1, and the entire contents of these three patent documents are hereby incorporated herein by reference.

[0281] The tandem electroluminescent device according to the present invention has a light emission wavelength between 300nm and 1000nm, preferably between 350nm and 900nm, and more preferably between 400nm and 800nm.

[0282] In other embodiments, the tandem electroluminescent device according to the present invention emits white light.

[0283] The present invention also relates to the application of the tandem electroluminescent device according to the present invention in various electronic devices, including, but not limited to, display devices, lighting devices, light sources, sensors, etc.

[0284] The present invention also relates to electronic devices comprising the tandem electroluminescent device according to the present invention, including, but not limited to, display devices, lighting devices, light sources, sensors, photovoltaic devices, and the like.

[0285] Example

[0286] The present invention will be described below in conjunction with preferred embodiments, but the present invention is not limited to the following embodiments. It should be understood that the attached claims summarize the scope of the present invention. Under the guidance of the concept of the present invention, those skilled in the art should be aware that certain changes made to the various embodiments of the present invention will be covered by the spirit and scope of the claims of the present invention.

[0287] Example 1: Evaporation-type tandem OLED

[0288]

[0289]

[0290] n-dopant1-n-dopant7 can be synthesized by the method described above, and other materials can be purchased commercially, such as HAT-CN purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd., HT-1, HT-2, BH, ET purchased from Zhengzhou Haikuo Optoelectronic Materials Co., Ltd., BD, LiQ, n-CGM1 purchased from Zhengzhou Aikemu Chemical Co., Ltd. The preparation method of tandem OLED1 and tandem OLED2 is as follows:

[0291] a. Cleaning of ITO (indium tin oxide) conductive glass substrate: Use various solvents (such as one or more of chloroform, acetone or isopropyl alcohol) for cleaning, and then perform ultraviolet ozone treatment.

[0292] b. Evaporation: The cleaned ITO substrate is moved into the vacuum vapor deposition equipment and heated in a high vacuum (1×10 -6 mbar), a HI layer (HAT-CN) with a thickness of 30nm was formed by a resistive heating evaporation source, and a 50nm HT-1 layer was sequentially evaporated on the HI layer, followed by a 10nm HT-2 layer evaporated on the HT-1 layer. Subsequently, two evaporation sources were used for co-evaporation, and the materials were vaporized at different rates to ensure that the weight ratio of BH:BD was 100:3, forming a 25nm light-emitting layer. ET and LiQ were placed in different evaporation units and co-deposited at a ratio of 50 wt% to obtain an electron transport layer. After that, an n-type charge generation layer material (n-CGM1) was used for the electron transport layer, and n-dopantx (x=1, 2) was used as a dopant, respectively, and a 20nm n-type charge generation layer was formed at a evaporation rate of 10:1 between n-CGM1 and n-dopantx (x=1, 2), and 10nm HAT-CN was evaporated on the n-type charge generation layer as a p-type charge generation layer. Then, a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer were sequentially deposited under the same conditions as above, and then 1 nm LiQ was evaporated as an electron injection layer, and finally an Al cathode with a thickness of 80 nm was deposited on the electron injection layer.

[0293] c. Packaging: The device is packaged with UV curable resin in a nitrogen glove box to obtain a series OLEDx (x=1, 2).

[0294] The preparation method of a single-section OLED (Comparative OLED 1) for comparison is as follows: Steps a and c are the same as those of the tandem OLED 1, and step b "evaporation" is as follows: the cleaned ITO substrate is moved into a vacuum vapor deposition device and heated in a high vacuum (1×10 -6 mbar), a resistive heating evaporation source is used to form a HI layer (HAT-CN) with a thickness of 30nm, and a 50nm HT-1 layer is sequentially evaporated on the HI layer, followed by a 10nm HT-2 layer evaporated on the HT-1 layer. Subsequently, two evaporation sources are used for co-evaporation, and the materials are vaporized at different rates to ensure that the weight ratio of BH:BD is 100:3, forming a 25nm light-emitting layer. ET and LiQ are placed in different evaporation units and co-deposited at a ratio of 50 weight % to obtain an electron transport layer; then 1nm LiQ is evaporated as an electron injection layer, and finally an Al cathode with a thickness of 80nm is deposited on the electron injection layer.

[0295] The current voltage (JV) characteristics of the OLED were recorded by computer controlled (Keithley 2400 source measurement unit) and (Keithley 2000 multimeter), while the brightness was measured by using a calibrated silicon photodiode (Newport 2112). The electroluminescence spectrum was measured by a spectrometer (Ocean Optics USB 2000). The performance of the comparative OLED 1, the tandem OLED 1 and the tandem OLED 2 is summarized in the following Table 1, where EQE (External Quantum Efficiency) represents the external quantum efficiency.

[0296] Table 1

[0297]

[0298] As can be seen from Table 1, the voltage and EQE in the stacked OLED device "tandem OLED1" are roughly twice that of the single-cell device "comparison OLED1"; the efficiency and voltage of "tandem OLED2" are also greatly improved.

[0299] The same method can also be used to prepare stacked OLEDs using n-dopant3-n-dopant7.

[0300] Example 2: Solution-processed tandem OLED

[0301] 1. Preparation of blue light polymer P1:

[0302]

[0303] The preparation of blue light polymer P1 is achieved by Suzuki condensation of diboronate monomer 1 (50 mol%) and dibromide monomer (containing 25 mol% of monomer 2, 15 mol% of monomer 3, and 10 mol% of monomer 4) with 0.8 mol% of tetrakis-(triphenylphosphine)-palladium (0) as a catalyst in a mixture of toluene (with some ethanol) and water with tripotassium phosphate as a base at 87°C for 48 hours (see Mueller et al., Nature, Vol421, p829).

[0304] 2. Preparation of cross-linkable n-CGM2:

[0305]

[0306] Synthesis of compound 1-1: 1,3-dibromobenzene (28.32 g, 0.12 mol) was dissolved in anhydrous tetrahydrofuran (700 mL), cooled to -78 °C, tert-butyl lithium ether solution (0.48 mol, 1.6 M) was slowly added in a nitrogen atmosphere, and the temperature was naturally raised to 5 °C after 1 hour. The obtained light yellow solution was slowly added with a tetrahydrofuran solution of 1,10-phenanthroline (40 g, 0.222 mol / 1.4LTHF) in a nitrogen atmosphere, and the reaction solution quickly turned dark red and continued to react at room temperature for 48 hours. After the reaction was completed, it was quenched with deionized water in an ice bath. The solvent was dried by rotary evaporation, and the obtained solid was dissolved in dichloromethane and washed with deionized water. After separation, manganese dioxide (270 g) was added to the organic layer. After stirring for 24 hours, it was filtered and the solvent was dried by rotary evaporation. It was further purified by column chromatography (silica gel: DCM: PE = 4:1) to obtain 19.3 g of white solid with a yield of 40%.

[0307] Synthesis of compound 1-2: 4-fluorobromobenzene (17.5 g, 0.1 mol) was dissolved in anhydrous tetrahydrofuran (600 mL), cooled to -78 ° C, and tert-butyl lithium ether solution (0.4 mol, 1.6 M) was slowly added in a nitrogen atmosphere. After 1 hour, the temperature was naturally raised to 5 ° C. The obtained light yellow solution was slowly added to the tetrahydrofuran solution of compound 1-1 (19.3 g, 44.4 mmol / 1LTHF) in a nitrogen atmosphere, and the reaction solution quickly turned dark red and continued to react at room temperature for 48 hours. After the reaction was completed, it was quenched with deionized water in an ice bath. The solvent was spin-dried, and the obtained solid was dissolved in dichloromethane and washed with deionized water. After separation, manganese dioxide (120 g) was added to the organic layer, stirred for 24 hours, filtered and the solvent was spin-dried, and further purified by column chromatography (silica gel: DCM: PE = 3: 1) to obtain 12.4 g of white solid with a yield of 45%.

[0308] Synthesis of compound n-CGM2: Compound 1-2 (12.4 g, 20 mmol), 7-octen-1-ol (5.64 g, 44 mmol), potassium hydroxide (4.94 g, 88 mmol) were dissolved in dry N,N-dimethylformamide (100 mL), and the temperature was raised to 120 ° C in a nitrogen atmosphere for 24 hours. After the reaction, the solvent was first dried, and the obtained solid was dissolved in dichloromethane and washed with deionized water. The organic layer obtained after separation was dried, and the obtained crude product was further purified by column chromatography (silica gel: DCM: PE = 4: 1) to obtain 14.3 g of white solid with a yield of 85%.

[0309] 3. Preparation of the composition

[0310] n-CGM2 and n-dopant1 were added to toluene at a weight ratio of 10:1 and a concentration of 11 mg / mL, heated and stirred to completely dissolve, and filtered to obtain solution 1 for later use.

[0311] 4. Preparation of solution-processed tandem PLED1:

[0312]

[0313] The preparation steps of the tandem PLED1 are as follows:

[0314] 1) The ITO conductive glass substrate was first cleaned using various solvents (chloroform → acetone → isopropanol) and then subjected to UV ozone plasma treatment.

[0315] 2) HIL: PEDOT:PSS (Clevios PVPAI4083) was spin-coated on an ITO conductive glass substrate in air in a clean room to obtain a HIL with a thickness of 80 nm; and then baked at 120° C. in air for 10 minutes to remove moisture.

[0316] 3) EML1: Prepare a solution of polymer P1 and photoacid 5 in toluene at a concentration of 15 mg P1 + 1 mg photoacid 5 per ml; spin-coat the solution on the HIL in an inert atmosphere of a nitrogen glove box to form a 60 nm EML1; irradiate the EML1 with a 365 nm UV-LED to cross-link it, and then bake it on a hot plate at 180°C for 10 minutes; then rinse the film with pure tetrahydrofuran and bake it on a hot plate at 100°C for 5 minutes.

[0317] 4) n-CGL: Solution 1 was spin-coated on EML 1 in an inert atmosphere of a nitrogen glove box to form a 20 nm n-CGL; it was then baked on a hot plate at 180° C. for 10 minutes to cross-link and solidify.

[0318] 5) p-CGL: PEDOT:PSS (Clevios PVPAI4083) was spin-coated on n-CGL in air in a clean room to obtain a p-CGL with a thickness of 20 nm; it was then baked at 120° C. for 10 minutes in a nitrogen glove box to remove moisture.

[0319] 6) EML2: Prepare a solution of polymer P1 and photoacid 5 in toluene at a concentration of 15 mg P1 + 1 mg photoacid 5 per ml; spin-coat the solution on p-CGL in an inert atmosphere of a nitrogen glove box to form a 60 nm EML2; irradiate the EML2 with a 365 nm UV-LED to cross-link it, and then bake it on a hot plate at 180°C for 10 minutes; then rinse the film with pure tetrahydrofuran and bake it on a hot plate at 100°C for 5 minutes.

[0320] 7) Cathode: Ba / Ag (6 / 100nm) in high vacuum (1×10 -6 It is formed by thermal evaporation at 1000 mbar.

[0321] 8) Packaging: The device was encapsulated with a UV curable resin in a nitrogen glove box.

[0322] 5. Comparison of the preparation of PLED1:

[0323] The comparison PLED1 is a single-section device. Compared with the preparation of the series-connected PLED1, steps 1), 2), 3), 7), and 8) are the same, and steps 4), 5), and 6) are omitted.

[0324] Table 2

[0325] Maximum current efficiency (Cd / A) <![CDATA[V@100Cd / cm 2 ]]> Compare with PLED1 3.6 4.21 Series PLED1 7.0 8.71

[0326] As can be seen from Table 2, the voltage and EQE in the stacked OLED device "Series PLED2" are roughly twice that of the single-cell device "Comparison PLED2".

[0327] A similar method can also be used to prepare the corresponding composition and solution-processed stacked OLED using n-dopant2-n-dopant7.

[0328] A stacked light-emitting device including a quantum dot light-emitting layer can be prepared in a similar manner, such as replacing the polymer light-emitting layer with a quantum dot light-emitting layer (see CN102916097A) in steps 3) and / or 6) of preparing PLED1 in Example 2.

[0329] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0330] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A tandem electroluminescent device comprising an anode, a cathode, at least two electroluminescent units disposed between the anode and the cathode, and a charge generation layer disposed between the electroluminescent units, wherein the charge generation layer comprises at least an n-type charge generation layer, characterized in that: The n-type charge generation layer comprises an n-type organic semiconductor material and a metal interlayer cation, wherein the n-type organic semiconductor material is at least partially reduced, and the metal interlayer cation is selected from the structures shown in general formulas (I-1) to (I-3): in: M 1 Selected from manganese or rhenium, M 2 is selected from iron, ruthenium or osmium, M 3 Selected from cobalt, rhodium or iridium; x1 is an integer between 1 and 5, x2 is an integer between 1 and 4, y1 is an integer between 1 and 6, and y2 is an integer between 1 and 5; R 1 , R 2 , R d Each occurrence is independently selected from H, D, or a linear alkyl, alkoxy, thioalkoxy group having 1 to 20 C atoms, or a branched or cyclic alkyl, alkoxy, thioalkoxy, silyl group having 3 to 20 C atoms, or a keto group having 1 to 20 C atoms, or an alkoxycarbonyl group having 2 to 20 C atoms, or an aryloxycarbonyl group having 7 to 20 C atoms, or a cyano group, a carbamoyl group, a haloformyl group, a formyl group, an isocyano group, an isocyanate group, a thiocyanate group, an isothiocyanate group, a hydroxyl group, a nitro group, CF3, Cl, Br, F, a crosslinkable group, or a substituted or unsubstituted aromatic group or heteroaromatic group having 5 to 60 ring atoms, or an aryloxy group or heteroaryloxy group having 5 to 60 ring atoms, or a combination of these groups.

2. The tandem electroluminescent device according to claim 1, characterized in that: The metal interlayer cation is selected from the following structures:

3. The tandem electroluminescent device according to claim 1 or 2, characterized in that: The n-type organic semiconductor material at least comprises a F, a cyano group or the following electron-withdrawing groups: in: n0 is 1, 2 or 3; X 1 -X 10 Independently selected from CR 3 or N, where two adjacent numbers cannot be N at the same time, and at least one of them is N; M1, M2, M3 are independently selected from N(R 8 )、C(R 8 )2、Si(R 8 )2、O、C=N(R 8 )、C=C(R 8 2. P(R 8 )、P(=O)R 8 , S, S=O, SO2 or none; R 3 , R 4 , R 5 , R 6 , R 7 , R 8 has the same meaning as R in claim 1 1 .

4. The tandem electroluminescent device according to any one of claims 1 to 3, characterized in that: The n-type organic semiconductor material is selected from the following structures and may be further substituted arbitrarily:

5. The tandem electroluminescent device according to any one of claims 1 to 4, characterized in that: The charge generation layer further includes a p-type charge generation layer.

6. The tandem electroluminescent device according to claim 5, characterized in that: The p-type charge generation layer includes a p-type doping material, and the LUMO of the p-type doping material is less than or equal to -4.9 eV.

7. The tandem electroluminescent device according to claim 5 or 6, characterized in that: The p-type charge generation layer includes a hole transport material.

8. A method for preparing a tandem electroluminescent device, characterized in that: An anode, a first electroluminescent unit, an n-type charge generation layer, a second electroluminescent unit and a cathode are sequentially deposited on a substrate, wherein the n-type charge generation layer is prepared as follows: 1) co-evaporating an n-type organic semiconductor material and a bimetallic sandwich compound onto a first electroluminescent unit by vacuum thermal evaporation to form a solid film, wherein the bimetallic sandwich compound comprises a structure represented by one of the following general formulae (II-1) to (II-3); or dispersing or dissolving the n-type organic semiconductor material and the bimetallic sandwich compound in an organic solvent to form a liquid solution or dispersion, then coating the liquid solution or dispersion onto the first electroluminescent unit, and removing the organic solvent to form a solid film; Where: M 1 、M 2 、M 3 , x1, x2, y1, y2, R 1 , R 2 , R d The same as defined in claim 1; 2) A redox reaction occurs in the solid film, causing at least a portion of the n-type organic semiconductor material to gain electrons, and the bimetallic sandwich compound to lose electrons to form two metal interlayer cations, and the two metal interlayer cations correspond to structures selected from one of the general formulas (I-1) to (I-3).

9. The method for preparing a tandem electroluminescent device according to claim 8, characterized in that: The bimetallic sandwich compound is selected from the following: Among them, Me4 represents 4 methyl substitutions, Me5 represents 5 methyl substitutions, and Me6 represents 6 methyl substitutions.

10. A composition, characterized in that It comprises at least one bimetallic sandwich compound represented by general formula (II-1) to (II-3) and at least one organic solvent.

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