An organic light emitting ink composition and an organic electroluminescent device comprising the same

Abstract

The application relates to the technical field of organic electroluminescent materials, and particularly discloses an organic luminescent ink composition and an organic electroluminescent device containing the same. The organic luminescent ink composition comprises two or more host materials with different carbon skeleton structures and at least one non-halogenated organic solvent; the two or more host materials with different carbon skeleton structures are all selected from compounds shown in formula I, and the weight average molecular weight of any one of the host materials is greater than 500 Da. The structure of the aromatic hydrocarbon host material is designed in the application, a mixed substance layer is formed in the ink film forming process, the strong pi-pi interaction between host material molecules with the same structure is broken due to the different structures of the host materials, the tendency of single-component host materials to aggregate in the luminescent ink is reduced, the ink stability and film forming quality are improved, and the efficiency and service life of the inkjet printing organic electroluminescent device are improved.

Description

Technical Field

[0001] This invention relates to the field of organic electroluminescent materials technology, and more particularly to an organic light-emitting ink composition and an organic electroluminescent device comprising the same. Background Technology

[0002] Organic electroluminescence refers to the phenomenon that thin-film devices made of organic electroluminescent materials emit light under the excitation of an electric field. Optoelectronic devices (organic light-emitting diodes, OLEDs) made using this principle have the characteristics of low power consumption, fast response, wide viewing angle, high resolution, wide temperature characteristics, light weight and rollability, and are widely used in high-end display and lighting fields.

[0003] Currently, organic light-emitting diodes (OLEDs) generally consist of multiple functional layers containing different organic materials. Their fabrication primarily employs vacuum evaporation, a method that produces high-quality films and allows for precise control over film thickness. However, vacuum evaporation suffers from low material utilization, demanding equipment requirements (such as high-precision masks), and stringent process conditions (<10). -7 Issues such as Torr are prevalent. These problems are particularly pronounced in the fabrication of large-size devices, leading to relatively high manufacturing costs. Therefore, solution-based organic functional layer fabrication processes, such as spin-coating, blade-coating, spray-coating, and inkjet printing, are gaining increasing attention in the field of large-size, high-precision OLED display manufacturing due to their advantages of high cost-effectiveness, wide applicability, and simple processes. Among these, inkjet printing technology, compared to traditional fabrication methods, features low energy consumption and high material utilization, and is considered a next-generation low-cost, non-contact, maskless fabrication method suitable for large-area patterning of various functional materials.

[0004] Inkjet printing requires printing inks containing functional materials; however, developing high-performance luminescent ink compositions for inkjet printing technology remains challenging. One major issue is that the host materials used in organic electroluminescence (OEC) are mostly organic molecules containing π-conjugated systems. Due to strong π-π interactions, they exhibit a significant tendency to aggregate. This aggregation of host materials affects device performance and leads to various problems. First, during ink storage, functional materials with a strong aggregation tendency risk gelling and precipitation during long-term storage. Second, during film preparation, as the solvent evaporates, the concentration of functional materials gradually increases, and functional materials with aggregation tendencies may agglomerate and clump, resulting in uneven film thickness. Furthermore, during operation, the aggregation of functional materials in the film can cause changes in film density, leading to defects, phase separation, and other problems, hindering carrier migration and exciton luminescence functions of the functional layer.

[0005] The aggregation of host materials is particularly detrimental to the emitting layer. In OLEDs, the blue emitting system is often a doped system, where the host material is responsible for carrier transport and recombination to form excitons, transferring exciton energy to the guest material. The guest material then emits light within the target wavelength range after receiving energy from the host material. Poor energy transfer between the host and guest materials leads to decreased device performance. Therefore, for ink compositions used in the emitting layer, host material aggregation causes host-guest phase separation, preventing the host material from effectively transferring excited-state energy to the guest material. This significantly reduces the energy transfer efficiency between the host and guest materials, drastically decreasing the lifetime and efficiency of inkjet-printed OLED devices. Furthermore, host materials can be classified into aromatic hydrocarbons and heteroatom hydrocarbons based on whether they contain heteroatoms. Using heteroatom-free aromatic compounds as OLED host materials generally results in a longer operating life. However, heteroatom-free host materials have lower polarity, making the aforementioned aggregation and precipitation problems particularly pronounced.

[0006] Therefore, providing an organic light-emitting ink composition that is not prone to aggregation is essential for improving the lifespan, efficiency, and other performance characteristics of organic electroluminescent devices. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides an organic light-emitting ink composition and an organic electroluminescent device containing the composition. By using two or more host materials with different structures, combined with a non-halogenated organic solvent, the self-aggregation of aromatic host materials in the solution method is effectively improved, thereby enhancing the overall performance of the organic electroluminescent device, such as its lifespan and efficiency.

[0008] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides an organic light-emitting ink composition comprising two or more host materials with different carbon skeleton structures and at least one non-halogenated organic solvent; wherein the two or more host materials with different carbon skeleton structures are all selected from compounds represented by Formula I, and the weight-average molecular weight of any one of the host materials is greater than 500 Da. I In formula I, Ar1 represents a non-fused aryl group with 6 to 30 hydrogen atoms, substituted or unsubstituted carbon atoms; Ar2 represents phenyl, biphenyl, terphenyl, naphthyl, naphthyl-substituted phenyl, phenanthryl, pyrene, benzo[a]phenanthryl, diphenylfluorenyl, or spirodifluorenyl; Each time L1 and L2 appear, they independently represent a single bond, phenylene, naphthylene, or biphenylene. m and n each independently represent 1 or 2; In Formula I, any hydrogen atom can be independently replaced by deuterium.

[0009] It should be noted that in this invention, "two or more main materials" refers to the different carbon skeleton structures of each main material. That is, two compounds with different deuteration rates but the same carbon skeleton are considered the same compound in this invention. When L1 is a single bond, regardless of whether m is 1 or 2, it represents a single bond; when L2 is a single bond, regardless of whether n is 1 or 2, it represents a single bond.

[0010] Preferably, the difference in glass transition temperature between any two of the main materials is less than 12°C.

[0011] Preferably, the glass transition temperature of any one of the main materials is greater than 120°C, and the glass transition temperature of at least one of the main materials is greater than 125°C.

[0012] By limiting the glass transition temperature of each main material, this invention can further ensure the excellent thermal stability of subsequent organic electroluminescent devices.

[0013] Preferably, the difference in weight-average molecular weight between any two of the main materials is less than 100 Da.

[0014] By limiting the weight-average molecular weight of different host materials, this invention can ensure that the thermal stability of different host materials is similar, thereby ensuring good compatibility between two or more host materials.

[0015] Preferably, in Formula I, the non-fused aryl group is selected from phenyl, biphenyl, or terphenyl.

[0016] Preferably, in Formula I, the fused aryl group is selected from naphthyl or phenanthrene.

[0017] More preferably, in Formula I, Ar1 is selected from substituted or unsubstituted phenyl groups or substituted or unsubstituted naphthyl groups.

[0018] More preferably, in Formula I, when Ar1 has a substituent, the substituent can be one or more, and the substituent is selected from deuterium or phenyl.

[0019] In a further preferred embodiment, in Formula I, Ar1 represents hydrogen, naphthyl, phenanthryl, phenyl, biphenyl, or terphenyl, and any one of the hydrogen atoms in Ar1 can be independently substituted with deuterium.

[0020] More preferably, in Formula I, Ar1 is selected from deuterated or non-deuterated phenyl groups or deuterated or non-deuterated naphthyl groups.

[0021] In the most preferred embodiment, Ar1 in Formula I is selected from deuterated or non-deuterated naphthyl groups.

[0022] Preferably, in Formula I, Ar2 is selected from... , , , , , , , , , or In Ar2, any hydrogen atom can be independently replaced by deuterium.

[0023] In a further preferred embodiment, Ar2 in Formula I is selected from... , , , , , , , , , , , or In Ar2, any hydrogen atom can be independently replaced by deuterium.

[0024] Preferably, in Formula I, L1 independently represents a single bond, a deuterated or non-deuterated phenylene, or a deuterated or non-deuterated naphthylene each time it appears.

[0025] In a further preferred embodiment, in Equation I, L1 independently represents a single bond each time it appears. or In L1, any hydrogen atom can be independently replaced by deuterium.

[0026] Preferably, in Equation I, L2 independently represents a single bond each time it appears. , , or In L2, any hydrogen atom can be independently replaced by deuterium.

[0027] More preferably, in Formula I, L1 and L2 are each independently selected from single bonds, , , or Either hydrogen atom in L1 or L2 can be independently replaced by deuterium.

[0028] More preferably, the compound represented by Formula I is selected from any of the following structural formulas. In Formula I, any hydrogen atom can be independently replaced by deuterium.

[0029] Preferably, the mass ratio of any two of the main materials is 7:3 to 3:7.

[0030] Preferably, the total concentration of the main material is 5 mg / mL to 20 mg / mL.

[0031] Preferably, the non-halogenated organic solvent includes alkylbenzene solvents, naphthalene solvents, ketone solvents, lactone solvents, benzoate solvents, phthalate solvents, ether solvents, nitrogen-containing heterocyclic solvents, sulfone solvents, or alicyclic alkane solvents.

[0032] More preferably, the alkylbenzene solvent includes at least one of toluene, tetramethylbenzene, o-diethylbenzene, butadiene, pentabenzene, cyclohexylbenzene, 1-hexylbenzene, 1-heptylbenzene, 1-octylbenzene, 1-decylbenzene, dodecylbenzene, or p-methylisopropylbenzene.

[0033] More preferably, the naphthalene solvent includes at least one of 1-methylnaphthalene, 1,4-dimethylnaphthalene, 1-methyltetrahydronaphthalene, 2-methyltetrahydronaphthalene, 5-methyltetrahydronaphthalene, 6-methyltetrahydronaphthalene, 1,4-dimethyltetrahydronaphthalene, decahydronaphthalene, 1-methoxynaphthalene, or 1-tetrahydronaphthone.

[0034] More preferably, the ketone solvent includes at least one of acetophenone, 3,3,5-trimethylcyclohexanone, cycloheptanone, frankincense, or isophorone.

[0035] More preferably, the lactone solvent includes at least one of butyrolactone, γ-valerolactone, or 6-caprolactone.

[0036] More preferably, the benzoic acid ester solvent includes at least one of methyl benzoate, methyl p-tert-butylbenzoate, ethyl benzoate, ethyl p-methylbenzoate, ethyl p-ethoxybenzoate, isobutyl benzoate, benzyl benzoate, or ethylhexyl benzoate.

[0037] More preferably, the phthalate solvent includes diallyl phthalate.

[0038] More preferably, the ether solvent includes at least one of diphenyl ether, dibenzyl ether, or 2-ethoxyanisole.

[0039] More preferably, the nitrogen-containing heterocyclic solvent includes at least one of quinoline or isoquinoline.

[0040] More preferably, the sulfone solvent includes sulfolane.

[0041] More preferably, the alicyclic alkane solvent includes at least one of 1,1'-bicyclohexane or butylcyclohexane.

[0042] More preferably, the non-halogenated organic solvent is a non-halogenated aromatic solvent.

[0043] Preferably, the organic light-emitting ink composition comprises two or more of the aforementioned non-halogenated organic solvents.

[0044] It should be noted that the two or more non-halogenated organic solvents contained in the organic light-emitting ink composition can be two from the same subtype (e.g., the organic light-emitting ink composition can contain two or more alkylbenzene solvents), or two from different subtypes (e.g., the organic light-emitting ink composition can contain one alkylbenzene solvent and one naphthalene solvent). In other words, the non-halogenated organic solvents in the organic light-emitting ink composition only need to be a mixture of solvents.

[0045] More preferably, the non-halogenated organic solvent is selected from at least two of cyclohexylbenzene, dodecylbenzene, 1,4-dimethyltetrahydronaphthalene, 2-ethoxyanisole, 6-caprolactone, methyl p-tert-butylbenzoate, ethyl benzoate, ethyl p-methylbenzoate, ethyl p-ethoxybenzoate, or 1-tetrahydronaphthone.

[0046] More preferably, the mass ratio of any two of the non-halogenated organic solvents is 9:1 to 1:1.

[0047] In the organic light-emitting ink composition provided by the present invention, the best dissolution effect can be achieved by using a preferred non-halogenated organic solvent to ensure the stability of the composition; by selecting a suitable mixed solvent (two or more non-halogenated organic solvents), the interaction between the mixed solvent and the host material can be utilized during the thermal annealing process to further avoid the aggregation of the host material, thereby further improving the film quality and device performance.

[0048] Preferably, the organic light-emitting ink composition further includes at least one guest material.

[0049] The present invention does not impose any special limitations on the specific structure of the guest material, and the above technical solution is basically applicable to all boron-nitrogen-containing organic light-emitting compounds in this field.

[0050] More preferably, the ratio of the total mass of the main material to the mass of the object material is 90:10 to 99.5:0.5.

[0051] In a second aspect, the present invention provides an organic electroluminescent device, wherein the raw material of the light-emitting layer comprises the aforementioned organic light-emitting ink composition.

[0052] The organic light-emitting ink composition provided by this invention can improve the overall performance of organic electroluminescent devices prepared using it, such as efficiency and lifespan, while meeting the requirements of inkjet printing processes for boiling point, viscosity, solubility and surface tension.

[0053] Preferably, the structure of the organic electroluminescent device includes an anode, a hole transport region, a light-emitting layer, an electron transport region, and a cathode sequentially disposed on a substrate; wherein the light-emitting layer is formed by inkjet printing of the organic light-emitting ink composition.

[0054] More preferably, the hole transport region includes a hole injection layer and a hole transport layer.

[0055] More preferably, the electron transport region includes an electron transport layer and an electron injection layer.

[0056] The present invention has the following beneficial effects: The organic light-emitting ink composition provided by this invention includes two or more host materials with different carbon skeleton structures and a non-halogenated organic solvent. By designing the structure of the aromatic host material, a layer of mixed substances is formed during the ink film formation process. The host materials with different structures break the strong π-π interaction between host material molecules with the same structure, thereby reducing the tendency of single-component host materials to aggregate in the light-emitting ink, improving ink stability and film quality, and thus improving the efficiency and lifespan of inkjet-printed organic electroluminescent devices. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0058] Terms and Definitions In this invention, the terms "preferred," "further preferred," "more preferred," "even more preferred," and "most preferred" refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0059] "Deuterium" refers to the hydrogen isotope deuterium.

[0060] "Deuteration" refers to the substitution of one or more hydrogen atoms in a group by deuterium.

[0061] The asterisk (*) indicates a connection point with other atoms.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0063] The following are specific examples. Unless otherwise specified, the solvents and reagents used in the examples can be purchased from conventional reagent suppliers, and the relevant compounds can be prepared by existing processes or conventional processes in the art.

[0064] The synthesis methods of the host material, guest material and their corresponding intermediate compounds in the embodiments of the present invention can be obtained by conventional technical means in the art.

[0065] The present invention does not impose any special limitation on the preparation method of the organic light-emitting ink composition. Conventional preparation methods in the art can be used to mix the host material, guest material and mixed solvent evenly.

[0066] The fabrication methods of the organic electroluminescent devices and the deposition methods of each functional layer in the embodiments of the present invention are conventional methods in the art, and will not be described in detail here.

[0067] Synthesis example 1 This synthetic example provides a method for synthesizing a host material (denoted as BH01), the chemical equation of which is shown below.

[0068] Under nitrogen protection, 40 mL of toluene and 15 mL of water were added to a Schlenk flask, followed by intermediates 01-a (3.52 g), 01-b (2.80 g), potassium phosphate (6.37 g), and tetraphenylphosphine palladium (0.35 g). The mixture was heated to 90 °C and reacted for 10 h. After cooling to room temperature, the mixture was filtered. The filter cake was dissolved in toluene and filtered to remove the solid insolubles. Recrystallization was then performed to give compound BH01 (3.29 g, yield: 65%). ESI + -MS: m / z 506.20 [M + ].

[0069] Synthesis example 2 This synthetic example provides a method for synthesizing a host material (denoted as BH02), the chemical equation of which is shown below.

[0070] Following the synthetic method of the main material BH01 in Synthesis Example 1, intermediate 01-b was replaced with intermediate 02-b (3.60 g) to obtain compound BH02 (3.51 g, yield: 60%), ESI + -MS: m / z 582.23 [M + ].

[0071] Synthesis example 3 This synthetic example provides a method for synthesizing a host material (denoted as BH03), the chemical equation of which is shown below.

[0072] Following the synthesis method of the main material BH01 in Synthesis Example 1, intermediate 01-a was replaced with 03-a (3.74 g) and intermediate 01-b was replaced with intermediate 03-b (4.65 g), yielding compound BH03 (4.39 g, yield: 68%). (ESI) + -MS: m / z644.25 [M + ].

[0073] 1 H-NMR (500mHz, DMSO-d6) δ 8.12 (s, 2H), 8.07 (t, 1H), 8.06 (s, 2H), 8.00 (s, 1H), 7.95 (s, 2H), 7.82 (s, 1H), 7.74 (s, 1H), 7.68 (s, 1H), 7.61(d, 2H), 7.60 – 7.57 (m, 2H), 7.54 (t, 1H), 7.52 (s, 4H), 7.50 (s, 2H), 7.42(d, 5H), 7.39 – 7.35 (m, 5H).

[0074] Synthesis example 4 This synthetic example provides a method for synthesizing a host material (denoted as BH04), the chemical equation of which is shown below.

[0075] Following the synthesis method of the main material BH01 in Synthesis Example 1, intermediate 01-a was replaced with 04-a (3.25 g) and intermediate 01-b was replaced with intermediate 04-b (4.00 g), yielding compound BH04 (3.45 g, yield: 61%). (ESI) + -MS: m / z564.27 [M + ].

[0076] Synthesis example 5 This synthetic example provides a method for synthesizing a host material (denoted as BH05), the chemical equation of which is shown below.

[0077] Following the synthetic method of the main material BH01 in Synthesis Example 1, intermediate 01-b was replaced with intermediate 05-b (5.00 g) to obtain compound BH05 (3.89 g, yield: 59%), ESI + -MS: m / z 658.27 [M + ].

[0078] Synthesis example 6 This synthetic example provides a method for synthesizing a host material (denoted as BH06), the chemical equation of which is shown below.

[0079] Following the synthesis method of the main material BH01 in Synthesis Example 1, intermediate 01-a was replaced with 06-a (4.24 g) and intermediate 01-b was replaced with intermediate 06-b (4.26 g), yielding compound BH06 (4.40 g, yield: 67%). (ESI) + -MS: m / z656.25 [M + ].

[0080] 1 H-NMR (500mHz, DMSO-d6) δ 8.40 (s, 1H), 8.20 (s, 1H), 8.11 (d, 4H), 8.06 – 8.05 (m, 4H), 8.03 (d, 3H), 7.99 (s, 1H), 7.96 (s, 1H), 7.91 (t, 1H),7.87 (s, 1H), 7.70 – 7.67 (m, 3H), 7.57 (d, 1H), 7.55 – 7.53 (m, 1H), 7.52(s, 7H), 7.51 – 7.46 (m, 2H), 7.39-7.35 (m, 1H).

[0081] Synthesis Example 7 This synthetic example provides a method for synthesizing a host material (denoted as BH07), the chemical equation of which is shown below.

[0082] Following the synthesis method of the main material BH01 in Synthesis Example 1, intermediate 01-a was replaced with 07-a (3.55 g) and intermediate 01-b was replaced with intermediate 07-b (3.76 g), yielding compound BH07 (3.39 g, yield: 63%). (ESI) + -MS: m / z537.25 [M + ].

[0083] Synthesis example 8 This synthetic example provides a method for synthesizing a host material (denoted as BH08), the chemical equation of which is shown below.

[0084] Following the synthesis method of the main material BH01 in Synthesis Example 1, intermediate 01-a was replaced with 08-a (4.24 g) and intermediate 01-b was replaced with intermediate 08-b (4.06 g), yielding compound BH08 (4.20 g, yield: 66%). (ESI) + -MS: m / z636.28 [M + ].

[0085] Synthesis example 9 This synthetic example provides a method for synthesizing a host material (denoted as BH09), the chemical equation of which is shown below.

[0086] Following the synthesis method of the main material BH01 in Synthesis Example 1, intermediate 01-a was replaced with 09-a (3.63 g) and intermediate 01-b was replaced with intermediate 09-b (4.30 g), yielding compound BH09 (3.72 g, yield: 62%). (ESI) + -MS: m / z599.34 [M + ].

[0087] 1 H-NMR (500mHz, DMSO-d6) δ 8.44 (s, 1H), 8.11 (s, 2H), 8.03 (s, 2H), 8.02 (s, 2H), 7.71 (s, 1H), 7.69 (s, 1H).

[0088] Synthesis example 10 This synthetic example provides a method for synthesizing a host material (denoted as BH10), the chemical equation of which is shown below.

[0089] Following the synthesis method of the main material BH01 in Synthesis Example 1, intermediate 01-a was replaced with 10-a (3.63 g) and intermediate 01-b was replaced with intermediate 10-b (4.43 g), yielding compound BH10 (3.98 g, yield: 65%). (ESI) + -MS: m / z612.42 [M + ].

[0090] Synthesis example 11 This synthetic example provides a method for synthesizing a host material (denoted as BH11), the chemical equation of which is shown below.

[0091] Following the synthesis method of the main material BH01 in Synthesis Example 1, intermediate 01-a was replaced with 10-a (3.63 g) and intermediate 01-b was replaced with intermediate 11-b (4.43 g), yielding compound BH11 (3.67 g, yield: 60%). (ESI) + -MS: m / z612.42 [M + ].

[0092] Synthesis example 12 This synthetic example provides a method for synthesizing a host material (denoted as BH12), the chemical equation of which is shown below.

[0093] Following the synthesis method of the main material BH01 in Synthesis Example 1, intermediate 01-a was replaced with 12-a (4.43 g) and intermediate 01-b was replaced with intermediate 12-b (3.63 g), yielding compound BH12 (3.56 g, yield: 58%). (ESI) + -MS: m / z612.42 [M + ].

[0094] Synthesis example 13 This synthetic example provides a method for synthesizing a host material (denoted as BH13), the chemical equation of which is shown below.

[0095] Following the synthesis method of the main material BH01 in Synthesis Example 1, intermediate 01-a was replaced with 10-a (3.63 g) and intermediate 01-b was replaced with intermediate 13-b (4.43 g), yielding compound BH13 (3.75 g, yield: 61%). (ESI) + -MS: m / z612.42 [M + ].

[0096] The molecular structural formula of the comparative host material used in this invention is as follows: DBH01、 DBH02, DBH03.

[0097] The molecular structural formula of the guest material used in this invention is as follows: BD01 BD02.

[0098] Verification Experiment 1 To verify that the organic light-emitting ink composition (hereinafter referred to as ink) provided by this invention can effectively prevent the aggregation tendency of the host material, a coating of the organic light-emitting ink composition (excluding the guest material) provided by this invention was applied and subjected to a quarter-wavelength fluorescence emission spectrum (PL) test (FWQH) after UV irradiation. Specifically, the following steps were included: The quartz substrate was cleaned and UV-treated for 10 minutes to remove contaminants. Each organic light-emitting ink composition shown in Tables 1 and 2 was spin-coated (where the mass ratio of compound 1 to compound 2 was 1:1, or the mass ratio of compound 1, compound 2, and compound 3 was 1:1:1, mixed with a non-halogenated organic solvent to form an organic light-emitting ink composition with a concentration of 10 mg / mL). The coating was applied using a spin coater at 1500 rpm for 30 seconds, pre-baked at 80°C for 20 minutes, and then baked at 140°C for 45 minutes to form a film of approximately 30 nm. Then, in an anhydrous and oxygen-free environment, the film was exposed to 365 nm ultraviolet light (3 mW / m²). 2 The samples were irradiated for 18 hours while being kept at room temperature. Samples from the same batch prepared on the same substrate were shielded from ultraviolet light with black light-blocking tape and used as unirradiated control films. After irradiation, the fluorescence emission spectra of the films were collected under 330 nm excitation. The intensities of the two maximum peaks were normalized, and the quarter-peak widths were measured and recorded. The results are shown in Tables 1 and 2.

[0099] It should be noted that ΔTg is defined as the difference between the highest and lowest values ​​of Tg, and ΔMw is defined as the difference between the highest and lowest values ​​of Mw.

[0100] Table 1 Performance test data of Examples 1-13 Table 2 Performance test data for comparison examples 1-9 The data above show that the films without guest materials, prepared by wet processing using the organic light-emitting ink composition provided by this invention, exhibited a change of less than 3 nm in the quarter-wave width (FWQH) after 18 hours of UV irradiation. In contrast, the films obtained by using only the host material of this invention, using a non-preferred solvent, or mixing a non-preferred host material all showed FWQH changes greater than 12 nm. Specifically, the host material and solvent used in Comparative Example 8 were not within the preferred range of this invention, resulting in a ΔFWQH > 25 nm. Comparative Example 9 used both host materials and solvents outside the preferred range of this invention and employed only a host material, resulting in a ΔFWQH > 30 nm. The comparative compound DBH02 used in Comparative Examples 3, 7, and 8 did not meet the requirement of Tg > 120 °C, and ΔTg > 12 °C. Comparative Example 7 showed a ΔMw > 100, indicating a significant increase in the corresponding ΔFWQH, suggesting significant aggregation.

[0101] The test results above show that the organic light-emitting ink composition provided by the present invention can significantly avoid the aggregation of the main material, while in the film layer of the above comparative effect example, the main material exhibits significant aggregation.

[0102] Example 1 This embodiment provides an organic light-emitting ink composition, denoted as INK01, comprising host material BH01, host material BH07, guest material BD01, ethyl benzoate (solvent 1), and cyclohexylbenzene (solvent 2).

[0103] The preparation method of the above-mentioned organic light-emitting ink composition includes the following steps: Anhydrous and oxygen-free ethyl benzoate (11.20 g) and cyclohexylbenzene (4.80 g) were weighed separately, with a mass ratio of 7:3. The cleaned and dried stir bar and vial were transferred to a glove box, and the two solvents were mixed until homogeneous. In the glove box, 0.12 g of host material BH01 (compound 1), 0.12 g of host material BH07 (compound 2), and 0.01 g of guest material BD01 were weighed and transferred to a vial containing the mixed solvent, and stirred. The resulting mixture was stirred at 80°C until the host materials were completely dissolved. The heating was then removed, and the mixture was slowly cooled to room temperature and filtered through a 0.2 μm PTFE membrane to obtain the organic light-emitting ink composition. 3 mL of the above organic light-emitting ink composition was used for performance testing, and the remainder was packaged and stored.

[0104] Examples 2-9 Examples 2-9 provide organic light-emitting ink compositions, respectively designated as INK02-INK09, and their raw material compositions are shown in Table 3. The proportions and preparation methods of the host compound 1, host compound 2, guest material, and solvent (including solvent 1 and solvent 2) are the same as in Example 1, and will not be repeated here.

[0105] Example 10 This embodiment provides an organic light-emitting ink composition, denoted as INK10, comprising host material BH06, host material BH10, host material BH13, guest material BDO2, ethyl benzoate (solvent 1), and cyclohexylbenzene (solvent 2).

[0106] The preparation method of the above-mentioned organic light-emitting ink composition includes the following steps: Anhydrous and oxygen-free ethyl benzoate (11.20 g) and cyclohexylbenzene (4.80 g) were weighed separately, with a mass ratio of 7:3. The cleaned and dried stir bar and vial were transferred to a glove box, and the two solvents were mixed until homogeneous. In the glove box, 0.08 g of host material BH06 (compound 1), 0.08 g of host material BH10 (compound 2), 0.08 g of host material BH13 (compound 3), and 0.01 g of guest material BD02 were weighed and transferred to a vial containing the mixed solvent, and stirred. The resulting mixture was stirred at 80°C until the host materials were completely dissolved. The heating was then removed, and the mixture was slowly cooled to room temperature and filtered through a 0.2 μm PTFE membrane to obtain the organic luminescent ink composition.

[0107] Example 11 This embodiment provides an organic light-emitting ink composition, denoted as INK11, whose raw material composition is shown in Table 3. The proportions and preparation methods of the host compound 1, host compound 2, guest material, and solvent (including solvent 1 and solvent 2) are the same as in Example 1, and will not be repeated here.

[0108] Example 12 This embodiment provides an organic light-emitting ink composition, denoted as INK12, whose raw material composition is shown in Table 3. The proportions and preparation methods of the host compound 1, host compound 2, host compound 3, guest material, and solvent (including solvent 1 and solvent 2) are the same as in Example 10, and will not be repeated here.

[0109] Example 13 This embodiment provides an organic light-emitting ink composition, denoted as INK13, whose raw material composition is shown in Table 3. The proportions and preparation methods of the host material compound 1, host material compound 2, guest material, and solvent (including solvent 1 and solvent 2) are the same as in Example 1, and will not be repeated here.

[0110] Comparative Examples 1-6 Comparative Examples 1-6 provide organic light-emitting ink compositions, respectively designated DINK01-DINK06. Their raw material composition and formulation are shown in Table 3. The proportions and preparation methods of the main material compound 1, main material compound 2, guest material, and solvents (including solvent 1 and solvent 2) are the same as in Example 1 and will not be repeated here.

[0111] Comparative Example 7 This comparative example provides an organic light-emitting ink composition, denoted as DINK07, whose raw material composition is shown in Table 3. The proportions and preparation methods of the host compound 1, host compound 2, host compound 3, guest material, and solvent (including solvent 1 and solvent 2) are the same as in Example 10, and will not be repeated here.

[0112] Comparative Examples 8-9 Comparative Examples 8 and 9 provide organic light-emitting ink compositions, respectively designated DINK08 to DINK09. Their raw material composition and formulation are shown in Table 3. The proportions and preparation methods of the main material compound 1, main material compound 2, guest material, and solvents (including solvent 1 and solvent 2) are the same as in Example 1 and will not be repeated here.

[0113] Table 3 Raw material composition of various organic light-emitting ink compositions Application Example 1 This application example provides an organic electroluminescent device, the structure of which includes an anode ITO, a hole injection layer PEDOT:PSS, a hole transport layer PVK, an emissive layer EML, an electron transport layer TPBi, an electron injection layer Liq, and a cathode Al, sequentially disposed on a substrate. PEDOT:PSS is an aqueous conductive polymer composite material composed of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonate (PSS).

[0114] The fabrication method of the above-mentioned organic electroluminescent device specifically includes the following steps: Step 1: Load the organic light-emitting ink composition INK01 from Example 1 into an ink container and assemble it into an inkjet printer, such as a Dimatix Materials Printer DMP-3000 (Fujifilm). Adjust the waveform, pulse time, and voltage of the ejected ink to optimize ink ejection and achieve a stable ink ejection range.

[0115] Step 2: Pattern the cleaned 50mm×50mm indium tin oxide (ITO) substrate to form a pixel defining layer, which contains holes for depositing inkjet printing material.

[0116] Step 3: The hole injection layer (HIL) and hole transport layer (HTL) materials are sequentially inkjet printed into the holes, and the solvent is removed by vacuum drying to obtain HIL / HTL films. The HIL film (30nm thick) is composed of PEDOT:PSS, and the HTL film (45nm thick) is composed of PVK.

[0117] Step 4: The organic light-emitting ink composition INK01 is printed onto the HIL / HTL film by inkjet printing, and the solvent is removed by high-temperature drying in a vacuum environment to obtain an organic light-emitting film (EML) (45nm thick).

[0118] Step 5: Electron transport layer (ETL) (30nm thick), electron injection layer (EIL) (1nm thick), and cathode (120nm thick) are sequentially formed on EML by vacuum thermal evaporation of TPBi, Liq, and aluminum (Al). Finally, the device is encapsulated to obtain an organic electroluminescent device.

[0119] The molecular structural formulas of each layer material (all of which are commercially available) in organic electroluminescent devices are as follows: Application Examples 2-13 Application Examples 2-13 each provide an organic electroluminescent device, the structure and preparation method of which are similar to those of Application Example 1, except that the organic light-emitting ink composition INK01 is replaced with organic light-emitting ink compositions INK02-INK13. All other parameters and conditions are the same as in Application Example 1 and will not be repeated here.

[0120] Compare and contrast examples 1-9 Comparative Application Examples 1-9 each provide an organic electroluminescent device, whose structure and preparation method are similar to those of Application Example 1, except that the organic light-emitting ink composition INK01 is replaced with organic light-emitting ink compositions DINK01-DINK09. All other parameters and conditions are the same as in Application Example 1 and will not be repeated here.

[0121] Verification Experiment 2 The performance parameters of the organic electroluminescent devices (blue OLED devices) in Application Examples 1-13 and Comparative Application Examples 1-9 were tested using the reference standard method, and the results are shown in Table 4.

[0122] At J = 10 mA / cm 2The driving voltage (Vop), luminance, and external quantum efficiency (EQE, measured as a percentage) of an organic electroluminescent device are determined at a given current density and are calculated as a function of luminous density from the current / voltage / luminous density characteristic line (IVL characteristic line) exhibiting Lambertian emission characteristics.

[0123] The lifetime LT is defined as the time after which the brightness decreases from the initial luminous intensity L0 to L1 when operating at a constant current density J. For example, LT95 refers to the lifetime of the fabricated blue OLED device at J = 20 mA / cm². 2 When operating, the luminous intensity drops to 95% of its initial value L0 after time LT95.

[0124] The testing instruments used for performance testing are as follows: Brightness: Tested using a PhotoResearch PR-655 spectral scanner; Current density and turn-on voltage: tested using a Keithley 2400 digital source meter; Lifetime testing: Using a silicon photonics-based OLED device lifetime testing system.

[0125] Table 4 Performance test results of organic electroluminescent devices As can be seen from the table above, compared with the comparative application examples, the organic electroluminescent device provided by this invention has higher efficiency and longer lifespan. This is because the organic light-emitting ink composition provided by this invention, through the rational selection of host materials and solvent combinations, fully utilizes the interactions between host materials and between host materials and solvents, thereby improving the anti-aggregation ability of host materials in ink and after film formation, thus improving the luminous efficiency of the device. It can also improve the stability and film quality of the organic light-emitting ink composition, so that the final prepared organic electroluminescent device exhibits significant advantages such as high efficiency and long lifespan.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An organic light-emitting ink composition, characterized in that, It includes two or more host materials with different carbon skeleton structures and at least one non-halogenated organic solvent; the two or more host materials with different carbon skeleton structures are all selected from the compounds shown in Formula I, and the weight-average molecular weight of any one of the host materials is greater than 500 Da; I In formula I, Ar1 represents hydrogen, a non-fused aryl group with 6 to 30 substituted or unsubstituted carbon atoms, or a fused aryl group with 10 to 16 substituted or unsubstituted carbon atoms; Ar2 represents phenyl, biphenyl, terphenyl, naphthyl, naphthyl-substituted phenyl, phenanthryl, pyrene, benzo[a]phenanthryl, diphenylfluorenyl, or spirodifluorenyl; Each time L1 and L2 appear, they independently represent a single bond, phenylene, naphthylene, or biphenylene. m and n each independently represent 1 or 2; In Formula I, any hydrogen atom can be independently replaced by deuterium.

2. The organic light-emitting ink composition as described in claim 1, characterized in that, The difference in glass transition temperature between any two of the main materials is less than 12°C; The glass transition temperature of any one of the main materials is greater than 120°C, and the glass transition temperature of at least one of the main materials is greater than 125°C; The difference in weight-average molecular weight between any two of the main materials is less than 100 Da.

3. The organic light-emitting ink composition as described in claim 1, characterized in that, In Formula I, the non-fused aryl group is selected from phenyl, biphenyl, or terphenyl; In Formula I, the fused aryl group is selected from naphthyl or phenanthrene.

4. The organic light-emitting ink composition as described in claim 3, characterized in that, In Formula I, Ar1 is selected from substituted or unsubstituted phenyl or substituted or unsubstituted naphthyl groups; when Ar1 has substituents, the substituents may be one or more, and the substituents may be selected from deuterium or phenyl. In Formula I, L1 independently represents either a deuterated or non-deuterated phenylene or a deuterated or non-deuterated naphthylene each time it appears.

5. The organic light-emitting ink composition as described in claim 3, characterized in that, In Formula I, Ar1 represents hydrogen, naphthyl, phenanthryl, phenyl, biphenyl or terphenyl, and any one of the hydrogen atoms in Ar1 can be independently substituted by deuterium; In Formula I, Ar2 is selected from , , , , , , , , , or In Ar2, any hydrogen atom can be independently replaced by deuterium; In Equation I, each occurrence of L1 independently represents a single bond. or In L1, any hydrogen atom can be independently replaced by deuterium; In Equation I, each occurrence of L2 independently represents a single bond. , , or In L2, any hydrogen atom can be independently replaced by deuterium.

6. The organic light-emitting ink composition as described in claim 5, characterized in that, In Formula I, Ar2 is selected from , , , , , , , , , , , or In Ar2, any hydrogen atom can be independently replaced by deuterium; In Equation I, L1 and L2 are each independently selected from single bonds, , , or Either hydrogen atom in L1 or L2 can be independently replaced by deuterium.

7. The organic light-emitting ink composition according to any one of claims 1 to 4, characterized in that, The compound represented by Formula I is selected from any of the following structural formulas. In Formula I, any hydrogen atom can be independently replaced by deuterium.

8. The organic light-emitting ink composition as claimed in claim 1, characterized in that, The non-halogenated organic solvents include alkylbenzene solvents, naphthalene solvents, ketone solvents, lactone solvents, benzoate solvents, phthalate solvents, ether solvents, nitrogen-containing heterocyclic solvents, sulfone solvents, or alicyclic alkane solvents; The organic light-emitting ink composition also includes at least one guest material.

9. The organic light-emitting ink composition as claimed in claim 8, characterized in that, The alkylbenzene solvents include at least one of toluene, tetramethylbenzene, o-diethylbenzene, butylbenzene, pentaphenyl, cyclohexylbenzene, 1-hexylbenzene, 1-heptylbenzene, 1-octylbenzene, 1-decylbenzene, dodecylbenzene, or p-methylisopropylbenzene; The naphthalene solvent includes at least one of 1-methylnaphthalene, 1,4-dimethylnaphthalene, 1-methyltetrahydronaphthalene, 2-methyltetrahydronaphthalene, 5-methyltetrahydronaphthalene, 6-methyltetrahydronaphthalene, 1,4-dimethyltetrahydronaphthalene, decahydronaphthalene, 1-methoxynaphthalene, or 1-tetrahydronaphthone. The ketone solvents include at least one of acetophenone, 3,3,5-trimethylcyclohexanone, cycloheptanone, frankincense, or isophorone; The lactone solvents include at least one of butyrolactone, γ-valerolactone, or 6-caprolactone. The benzoic acid ester solvents include at least one of methyl benzoate, methyl p-tert-butylbenzoate, ethyl benzoate, ethyl p-methylbenzoate, ethyl p-ethoxybenzoate, isobutyl benzoate, benzyl benzoate, or ethylhexyl benzoate. The phthalate solvents include diallyl phthalate; The ether solvent includes at least one of diphenyl ether, dibenzyl ether, or 2-ethoxyanisole; The nitrogen-containing heterocyclic solvent includes at least one of quinoline or isoquinoline; The sulfone solvent includes sulfolane; The alicyclic alkane solvent includes at least one of 1,1'-bicyclohexane or butylcyclohexane.

10. The organic light-emitting ink composition as claimed in claim 8, characterized in that, The mass ratio of any two of the main materials is 7:3 to 3:7; the total concentration of the main materials is 5 mg / mL to 20 mg / mL. The organic light-emitting ink composition comprises two or more of the aforementioned non-halogenated organic solvents; the mass ratio of any two of the aforementioned non-halogenated organic solvents is 9:1 to 1:1; The ratio of the total mass of the main material to the mass of the object material is 90:10 to 99.5:0.

5.

11. An organic electroluminescent device, characterized in that, The raw material of its light-emitting layer includes the organic light-emitting ink composition according to any one of claims 1 to 10.

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