Antioxidant composite hole transport material with core-shell-matrix three-level structure and preparation method and application thereof

Abstract

This invention discloses an antioxidant composite hole transport material with a core-shell-matrix three-level structure, its preparation method, and its applications. It consists of a core layer, a shell layer, and a matrix: the core layer is metal ion-doped nickel oxide nanoparticles; the shell layer is an aromatic amino acid molecular layer coated on the surface of the metal ion-doped nickel oxide nanoparticles through coordination bonds and / or hydrogen bonds; the matrix is ​​an organic hole transport material; the aromatic amino acid-modified metal ion-doped nickel oxide nanoparticles are uniformly dispersed in the organic hole transport material, forming a core-shell-matrix three-level structure. This invention utilizes Ni… 2+ The "aromatic amino acid" inorganic-organic dual-site synergistic antioxidant network achieves in-situ active protection of the organic hole transport layer. 2+ Preferential oxidation sacrifices and consumes reactive oxygen species, while the amino acid shell quenches free radicals and terminates the chain reaction. The spatial proximity of the two produces a synergistic effect.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic display materials technology, and in particular to an antioxidant composite hole transport material with a core-shell-matrix three-level structure, its preparation method, and its application. Background Technology

[0002] Quantum dot light-emitting diodes (QLEDs) have shown great potential in high-definition displays and solid-state lighting due to their advantages such as high color purity, tunable color, and solution-processability, becoming a core technology for next-generation displays. However, the commercial application of QLEDs is still limited by the operational stability of the devices, with the electrochemical oxidative degradation of the hole transport layer (HTL) being a key factor leading to performance degradation. Commonly used organic hole transport materials (such as PVK, TFB, PEDOT:PSS, etc.) are prone to generating reactive oxygen species under the influence of an electric field and oxygen, inducing molecular chain breakage or carbonylation, forming deep-level traps, ultimately causing device efficiency roll-off and brightness decay.

[0003] Current technologies for improving QLED stability mainly focus on three aspects: encapsulation to isolate oxygen, development of novel stable HTL materials, and optimization of device structure. However, encapsulation technology is a passive defense and cannot suppress electrochemical oxidation within the material. The development of novel materials often faces contradictions such as complex synthesis, high cost, or low mobility. Structural optimization does not address the intrinsic stability of the material. Therefore, how to endow existing mature organic hole transport materials with active oxidation resistance while retaining their advantages has become a pressing technical challenge in this field. Summary of the Invention

[0004] To overcome the shortcomings of existing hole transport materials, such as easy oxidation and degradation and poor stability, this invention provides an antioxidant composite hole transport material with a core-shell-matrix three-level structure, its preparation method, and its applications. This antioxidant composite hole transport material significantly improves the lifetime and efficiency of devices.

[0005] The further technical problem to be solved by the present invention is to provide a composite hole transport layer, a method for preparing the same, and a quantum dot light-emitting diode.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An antioxidant composite hole transport material with a core-shell-matrix three-level structure is disclosed, comprising a core layer, a shell layer, and a matrix: the core layer consists of metal ion-doped nickel oxide nanoparticles, wherein divalent nickel accounts for no less than 80% of the total nickel content in the metal ion-doped nickel oxide nanoparticles; the shell layer consists of an aromatic amino acid molecular layer coated on the surface of the metal ion-doped nickel oxide nanoparticles via coordination bonds and / or hydrogen bonds; and the matrix is ​​an organic hole transport material.

[0008] Among them, aromatic amino acid-modified metal ion-doped nickel oxide nanoparticles are uniformly dispersed in organic hole transport materials to form a three-level structure of "core-shell-matrix";

[0009] The mass ratio of the aromatic amino acid to the metal ion-doped nickel oxide nanoparticles is 1:5 to 1:20; the mass ratio of the aromatic amino acid-modified metal ion-doped nickel oxide nanoparticles to the organic hole transport material is 1:99 to 40:60.

[0010] The doped metal ions in the metal ion-doped nickel oxide nanoparticles are selected from at least one of magnesium, copper, lithium, and aluminum, and the atomic percentage of the doped metal ions in the total metal cations is 0.5% to 10%.

[0011] The aromatic amino acid is selected from at least one of tryptophan, tyrosine, and histidine. The aromatic amino acid forms a coordinate bond or hydrogen bond with the surface of the metal ion-doped nickel oxide nanoparticles through a carboxyl group and / or an amino group.

[0012] The organic hole transport material is selected from at least one of polyvinylcarbazole, poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine), poly3,4-ethylenedioxythiophene / polystyrene sulfonate, or N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine.

[0013] The particle size of the metal ion-doped nickel oxide nanoparticles is 3-15 nm.

[0014] A method for preparing the above-mentioned antioxidant composite hole transport material with a core-shell-matrix three-level structure includes the following steps:

[0015] (1) Metal ion-doped nickel oxide nanoparticles are reacted with aromatic amino acids in a solvent for surface modification at a temperature of 40-80℃ for 2-24 hours to obtain aromatic amino acid-modified nanoparticles; the mass ratio of the aromatic amino acids to the metal ion-doped nickel oxide nanoparticles is 5% to 20%.

[0016] (2) Disperse the aromatic amino acid-modified nanoparticles in an organic solvent to obtain a nanoparticle dispersion;

[0017] (3) The nanoparticle dispersion is mixed with the organic hole transport material solution and homogenized to obtain an antioxidant composite hole transport material with a core-shell-matrix three-level structure;

[0018] The homogenization process involves alternating between ultrasound and stirring, with a total processing time of 1-12 hours.

[0019] A composite hole transport layer comprising the aforementioned antioxidant composite hole transport material having a core-shell-matrix three-level structure.

[0020] A method for preparing a composite hole transport layer includes the following steps:

[0021] (1) Metal ion-doped nickel oxide nanoparticles were reacted with aromatic amino acids in a solvent to carry out surface modification reaction. The reaction temperature was 40-80℃ and the time was 2-24 hours to obtain aromatic amino acid-modified nanoparticles.

[0022] (2) Disperse the aromatic amino acid-modified nanoparticles in an organic solvent to obtain a nanoparticle dispersion;

[0023] (3) The nanoparticle dispersion is mixed with the organic hole transport material solution and homogenized to obtain an antioxidant composite hole transport material with a core-shell-matrix three-level structure;

[0024] (4) The antioxidant composite hole transport material with a core-shell-matrix three-level structure is deposited on a substrate by solution processing and then annealed to form a composite hole transport layer; wherein the annealing temperature is 100-150℃ and the time is 10-60 minutes.

[0025] A quantum dot light-emitting diode includes an anode, a cathode, and a functional layer disposed between the anode and the cathode, wherein the functional layer includes the aforementioned composite hole transport layer.

[0026] The quantum dot light-emitting diode is a red, green, or blue QLED device.

[0027] The above-mentioned antioxidant composite hole transport material with a core-shell-matrix three-level structure is used in the fabrication of optoelectronic display devices.

[0028] The beneficial effects of this invention are as follows:

[0029] (1) Enhanced stability: This invention utilizes "Ni" 2+ -Aromatic amino acids" inorganic-organic dual-site synergistic antioxidant network, achieving in-situ active protection of the organic hole transport layer. 2+ Preferential oxidation sacrifices and consumes reactive oxygen species, while the amino acid shell quenches free radicals and terminates the chain reaction. The spatial proximity of the two results in synergistic effects, and the antioxidant capacity and durability are significantly better than those of a single component.

[0030] (2) Comprehensive synergistic optimization of optoelectronic performance: doping ions enhance the intrinsic conductivity of nanoparticles and provide additional hole transport channels for the composite layer; the conjugated structure of amino acids forms a smooth energy level transition at the inorganic / organic interface, reducing the injection barrier; the energy level bridging effect of uniformly dispersed nanoparticles and amino acids jointly optimizes hole injection and transport, and the device efficiency roll-off is significantly suppressed.

[0031] (3) Enhanced interfacial compatibility and film quality: Aromatic amino acids are firmly anchored to the surface of nanoparticles through coordination / hydrogen bonds. Their aromatic ring side chains and the aromatic backbone of organic HTL generate π-π conjugation, realizing molecular-level bridging between the inorganic core and the organic matrix, ensuring long-term stability of the composite ink and uniform, dense and defect-free film.

[0032] (4) Wide range of technical applicability: The composite hole transport layer of the present invention can be adapted to a variety of commonly used organic HTL materials and quantum dot light-emitting layers of different colors. By selecting different doping ions and amino acid types, the electrical properties can be directionally controlled to meet the needs of differentiated applications. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the core-shell-matrix three-level structure of the antioxidant composite hole transport material of the present invention. The arrows in the diagram indicate the hole transport direction.

[0034] Figure 2 The "Ni" of the present invention 2+ - Schematic diagram of the mechanism of action of the "aromatic amino acid" synergistic antioxidant network.

[0035] The figures are labeled as follows: ①-core layer; ②-shell layer; ③-matrix. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0037] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0038] Unless otherwise specified, the reagents used in the embodiments of the present invention are all conventional raw materials or reagents, and the experimental methods used are all conventional methods in the art unless otherwise specified.

[0039] This invention proposes to construct a core-shell-matrix three-level structure, introducing aromatic amino acid-modified metal ion-doped nickel oxide nanoparticles into an organic hole transport matrix, and utilizing Ni 2+ The preferential oxidation sacrifice and free radical scavenging ability of amino acids form an inorganic-organic dual-site synergistic antioxidant network, which actively inhibits oxidation reactions from the inside of the material, while achieving synergistic optimization of interfacial compatibility and electrical properties.

[0040] For details, see Figure 1 This invention provides an antioxidant composite hole transport material with a core-shell-matrix three-level structure, comprising a core layer ①, a shell layer ②, and a matrix ③: the core layer ① is metal ion-doped nickel oxide nanoparticles, wherein divalent nickel accounts for no less than 80% of the total nickel content in the metal ion-doped nickel oxide nanoparticles; the shell layer ② is an aromatic amino acid molecular layer coated on the surface of the metal ion-doped nickel oxide nanoparticles through coordination bonds and / or hydrogen bonds; the matrix ③ is an organic hole transport material;

[0041] Among them, aromatic amino acid-modified metal ion-doped nickel oxide nanoparticles are uniformly dispersed in organic hole transport materials, forming a three-level structure of "core-shell-matrix".

[0042] The hole transport direction of this antioxidant composite hole transport material with a core-shell-matrix three-level structure is matrix → shell → core.

[0043] See Figure 2 The present invention relates to an antioxidant composite hole transport material with a core-shell-matrix three-level structure, specifically the Ni 2+ The specific mechanism of action of the "aromatic amino acid" synergistic antioxidant network is as follows: Amino acid molecules have a unique "amphiphilic" structure, with their carboxyl groups (-COOH) and amino groups (-NH2) acting as "anchors," firmly binding to the surface of nanoparticles through coordination bonds or hydrogen bonds; their hydrophobic aromatic ring side chains extend outward, generating strong π-π conjugated interactions with the aromatic backbone of the organic hole transport layer matrix, solving the problem of inorganic nanoparticle aggregation in organic systems; their side chains can also effectively quench singlet oxygen (… 1 O2) and capture peroxide radicals, and can react with Ni in the core. 2+ Tightly coupled in space, Ni 2+ Preferential oxidation and sacrifice occur, with amino acid side chains quenching various reactive oxygen species and terminating free radical chain reactions, forming a unique "inorganic-organic dual-site synergistic antioxidant network." Even if the surface Ni... 2+ Partially oxidized to Ni 3+The amino acid shell on it can still provide continuous protection; in addition, its conjugated structure can form a smoother energy level transition between the valence band top of the inorganic particles and the HOMO (highest occupied molecular orbital) energy level of the organic hole transport layer, reducing the hole injection barrier and improving the injection efficiency.

[0044] Example 1: Tryptophan-modified Cu:NiO x / TFB composite hole transport layer and its red QLED device.

[0045] I. Preparation Steps

[0046] (1) Preparation of Cu-doped nickel oxide nanoparticles (Cu:NiO) x Cu:NiO was prepared using an emulsion method with a Cu doping content of 3% (atomic percentage). Nickel nitrate hexahydrate and copper nitrate hexahydrate were dissolved together in deionized water, and tetramethylammonium hydroxide pentahydrate was added to prepare a precipitate solution. The precipitate solution was centrifuged to obtain the precipitate, which was then dried. The dried precipitate was calcined in a muffle furnace at 300°C for 3 hours to obtain Cu:NiO. x Nanoparticles, XPS analysis shows Ni 2+ It accounts for 85% of the total nickel content.

[0047] (2) Tryptophan surface modification:

[0048] S01: Weigh 100 mg of Cu:NiO x Nanoparticles were dispersed in 50 mL of deionized water and ultrasonically treated for 30 min to obtain a dispersion.

[0049] S02: Weigh 15 mg of tryptophan and add it to the above dispersion to obtain a mixture.

[0050] S03: The mixture was placed in a 60℃ water bath and stirred at 300 rpm for 12 hours. After the reaction was complete, the solid was collected by centrifugation at 10000 rpm for 15 minutes. The solid was washed twice with deionized water and twice with ethanol, centrifuged after each wash. The washed solid was placed in a vacuum drying oven and dried at 40℃ for 12 hours to obtain Cu:NiO with approximately 12 wt% tryptophan grafting. x Nanoparticles (denoted as Trp@Cu:NiO) x ).

[0051] II. Formulation of antioxidant composite hole transport material with a core-shell-matrix three-level structure.

[0052] S1: Add 20 mg Trp@Cu:NiO x Nanoparticles were dispersed in 2 mL of chlorobenzene and sonicated for 1 hour to obtain a nanoparticle dispersion with a concentration of 10 mg / mL.

[0053] S2: Weigh 40 mg of poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB Mw≈50,000), dissolve it in 5 mL of chlorobenzene, and prepare a TFB solution with a concentration of 8 mg / mL.

[0054] S3: Add 0.5 mL of Trp@Cu:NiO x The nanoparticle dispersion was mixed with 2.5 mL of TFB solution (volume ratio 1:5, mass ratio approximately 1:4). The mixture was ultrasonically treated for 30 minutes, then magnetically stirred for 2 hours, and repeated 3 times, for a total treatment time of approximately 6 hours, to obtain a uniform and stable antioxidant composite hole transport material with a core-shell-matrix three-level structure (hereinafter referred to as composite ink). The composite ink showed no significant sedimentation after standing at room temperature for 30 days.

[0055] III. Fabrication of Red QLED Devices

[0056] S-1: ITO glass is used as the anode substrate. The ITO glass is ultrasonically cleaned for 15 minutes each with cleaning agent, deionized water, acetone and isopropanol in sequence, dried with nitrogen, and then treated with ultraviolet-ozone for 15 minutes.

[0057] S-2: The above composite ink was spin-coated onto the ITO substrate at 3000 rpm for 40 seconds. After spin-coating, it was annealed on a hot plate at 120°C for 30 minutes to form a composite hole transport layer with a thickness of approximately 35 nm.

[0058] S-3: Transfer the annealed substrate to a nitrogen glove box. Spin-coat CdSe / ZnS core-shell structured red quantum dots (emission wavelength 625 nm, concentration 15 mg / mL in n-octane) at 2000 rpm for 45 seconds, and anneal on an 80°C hot plate for 10 minutes to form a quantum dot luminescent layer of about 25 nm thickness.

[0059] S-4: Spin-coat an electron transport layer of ZnO nanoparticles (concentration 20 mg / mL in ethanol) at 3000 rpm for 30 seconds, and anneal on an 80℃ hot plate for 10 minutes to form an electron transport layer of about 40 nm thickness.

[0060] S-5: Transfer the sample to the vacuum evaporation chamber, where the vacuum level is better than 5×10⁻⁶. -4 Under Pa conditions, an Al electrode with a thickness of 100 nm was deposited at a rate of 0.1 nm / s, and the effective area of ​​the device was 4 mm. 2 .

[0061] IV. Performance Testing

[0062] The device has a power-on voltage of 2.0 V and a maximum EQE of 21.2% at 1000 cd / m². 2 The EQE at brightness is 19.8%, and the T80 (time to 80% brightness decay) lifespan is 620 hours.

[0063] Example 2: Tryptophan-modified Mg:NiO x / TFB composite hole transport layer and its red QLED device.

[0064] I. Preparation Steps

[0065] (1) Preparation of Mg-doped nickel oxide nanoparticles (Mg:NiO) x The same method as in Example 1 was used, except that the dopant was changed to magnesium nitrate hexahydrate. XPS analysis showed that Ni 2+ It accounts for 86% of the total nickel content.

[0066] (2) Tryptophan surface modification: Same as step (2) in Example 1, to obtain Mg:NiO with a tryptophan grafting amount of about 11 wt%. x Nanoparticles (Trp@Mg:NiO) x ).

[0067] II. Preparation of composite inks and device fabrication.

[0068] The steps are the same as those in steps two and three of Example 1.

[0069] III. Performance Testing

[0070] The device has a power-on voltage of 2.1 V and a maximum external quantum efficiency (EQE) of 19.8% at 1000 cd / m². 2 The EQE at luminance is 18.5%, with no significant efficiency roll-off. At 1000 cd / m²... 2 At initial brightness, the T80 has a lifespan of 850 hours.

[0071] Example 3: Tryptophan-modified Li:NiO x / TFB composite hole transport layer and its red QLED device.

[0072] I. Preparation Steps

[0073] (1) Preparation of Li-doped nickel oxide nanoparticles (Li:NiO) x The same method as in Example 1 was used, except that the dopant was changed to lithium nitrate. XPS analysis showed that Ni 2+ It accounts for 84% of the total nickel content.

[0074] (2) Tryptophan surface modification: Same as step (2) in Example 1, to obtain Li:NiO with a tryptophan grafting amount of about 12 wt%.x Nanoparticles (Trp@Li:NiO) x ).

[0075] II. Formulation of Composite Ink and Device Preparation

[0076] The steps are the same as those in steps two and three of Example 1.

[0077] III. Performance Testing

[0078] The device has a power-on voltage of 1.9 V and a maximum EQE of 19.5% at 1000 cd / m². 2 The EQE at brightness is 18.0%. The T80 has a lifespan of 580 hours.

[0079] Example 4: Tryptophan-modified Al:NiO x / TFB composite hole transport layer and its red QLED device.

[0080] I. Preparation Steps

[0081] (1) Preparation of Al-doped nickel oxide nanoparticles (Al:NiO) x The same method as in Example 1 was used, except that the dopant was changed to aluminum nitrate nonahydrate. XPS analysis showed that Ni 2+ It accounts for 83% of the total nickel content.

[0082] (2) Tryptophan surface modification: Same as step (2) in Example 1, to obtain Al:NiO with an tryptophan grafting amount of about 11 wt%. x Nanoparticles (Trp@Al:NiO) x ).

[0083] II. Preparation of composite inks and device fabrication.

[0084] The steps are the same as those in steps two and three of Example 1.

[0085] III. Performance Testing

[0086] The device has a power-on voltage of 2.0 V and a maximum EQE of 20.1% at 1000 cd / m². 2 The EQE at brightness is 18.9%, and the T80 lifespan is 680 hours.

[0087] Example 5: Tyrosine-modified Li:NiO x / PVK composite hole transport layer and its application in green QLED.

[0088] I. Preparation Steps

[0089] (1) Preparation of Li-doped nickel oxide nanoparticles (Li:NiO) x): The same steps as in Example 3 (1) are used.

[0090] (2) Tyrosine surface modification:

[0091] S01: Weigh out 100 mg of Li:NiO x Nanoparticles were dispersed in 50 mL of deionized water and ultrasonically treated for 30 min.

[0092] S02: Weigh 18 mg of tyrosine and add it to the above dispersion.

[0093] S03: The mixture was placed in a 70°C water bath and stirred at 300 rpm for 12 hours. Subsequent washing and drying steps were the same as in step (2) of Example 1, yielding Li:NiO with a tyrosine grafting content of approximately 13 wt%. x Nanoparticles (Tyr@Li:NiO) x ).

[0094] II. Preparation of Composite Ink

[0095] S1: Add 20 mg Tyr@Li:NiO x Dispersed in 2 mL of chlorobenzene, a dispersion of 10 mg / mL was obtained. After sonication for 1 hour, a nanoparticle dispersion with a concentration of 10 mg / mL was obtained.

[0096] S2: Weigh 50 mg of polyvinylcarbazole (PVK, Mw≈1,100,000), dissolve it in 5 mL of chlorobenzene, and prepare a PVK solution with a concentration of 10 mg / mL.

[0097] S3: Add 0.5 mL of Tyr@Li:NiO x The nanoparticle dispersion was mixed with 2.5 mL of PVK solution and subjected to alternating ultrasonic and stirring treatment for a total treatment time of 6 hours to obtain a uniform and stable composite ink.

[0098] III. Fabrication of Green QLED Devices

[0099] The same device structure as in Example 1 was used, except that the quantum dot emitting layer used CdSe / ZnS core-shell structure green quantum dots (emitting wavelength 525 nm, concentration 15 mg / mL in n-octane).

[0100] IV. Performance Testing

[0101] The device has a power-on voltage of 2.3 V and a maximum EQE of 17.5% at 1000 cd / m². 2 The EQE at brightness is 16.2%. The T80 has a lifespan of 720 hours.

[0102] Example 6: Histidine-modified Cu:NiO x / TFB composite hole transport layer and its application in red QLED.

[0103] I. Preparation Steps

[0104] (1) Preparation of Cu-doped nickel oxide nanoparticles (Cu:NiO) x ): Same as step (1) in Example 1.

[0105] (2) Histidine surface modification:

[0106] S01: Weigh 100 mg of Cu:NiO x Nanoparticles were dispersed in 50 mL of deionized water and ultrasonically treated for 30 min.

[0107] S02: Weigh 16 mg of histidine and add it to the above dispersion.

[0108] S03: The mixture was placed in a 60°C water bath and stirred at 300 rpm for 12 hours. The subsequent washing and drying steps were the same as in step (2) of Example 1, resulting in Cu:NiO with a histidine grafting amount of approximately 10 wt%. x Nanoparticles (His@Cu:NiO) x ).

[0109] II. Formulation of Composite Ink and Device Preparation

[0110] The steps are the same as those in steps two and three of Example 1.

[0111] III. Performance Testing

[0112] The device has a power-on voltage of 2.1 V and a maximum EQE of 18.9% at 1000 cd / m². 2 The EQE at brightness is 17.6%. The T80 has a lifespan of 780 hours.

[0113] Example 7: The effect of different composite ratios on device performance.

[0114] Using Trp@Cu:NiO from Example 1 x / TFB system, changing Trp@Cu:NiO x A series of red QLED devices were fabricated using TFB mass ratios (1:99, 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 40:60).

[0115] Performance test results: When Trp@Cu:NiO xThe device exhibits optimal overall performance when the TFB mass ratio is between 5:95 and 25:75. The optimal balance is achieved within the range of 10:90 to 15:85, with EQE > 19% and T80 > 800 hours. When the mass ratio is too low (< 5:95), T80 < 400 hours; when the mass ratio is too high (> 30:70), film uniformity decreases, and EQE drops below 17%.

[0116] Example 8: Effect of different amino acid dosages on modification effect.

[0117] Cu:NiO from Example 1 x Nanoparticles were prepared by varying the mass ratio of tryptophan to nanoparticles to 1:5, 1:8, 1:10, 1:12, 1:15, and 1:20, respectively, to prepare a series of Trp@Cu:NiO nanoparticles. x Nanoparticles.

[0118] Performance testing: The modification effect was optimal when the mass ratio of amino acids to nanoparticles was 1:8 to 1:15, with a grafting amount of 10-15 wt%, the best dispersion stability, and a film roughness Rq < 2 nm. When the ratio was too high (1:5), multilayer physical adsorption occurred, and the film resistance increased slightly; when the ratio was too low (1:20), the coverage was incomplete, and Rq > 3 nm.

[0119] Example 9: Preparation of a composite hole transport layer by inkjet printing.

[0120] Using Trp@Cu:NiO from Example 1 x / TFB composite ink was used to deposit a hole transport layer via inkjet printing. The printing substrate temperature was set to 40°C, the droplet spacing was 30 μm, and three layers were printed. After printing, the layers were annealed on a hot plate at 120°C for 30 minutes to form a composite hole transport layer approximately 40 nm thick. The subsequent QLED device fabrication steps were the same as in Example 1.

[0121] Performance testing: The device prepared by inkjet printing has a maximum EQE of 18.5% and a T80 life of 800 hours, which is comparable to the performance of the device prepared by spin coating, proving that the technical solution of this invention is compatible with the inkjet printing process.

[0122] Example 10: Application of composite hole transport layer in different HTL (hole transport layer) matrices.

[0123] (1) PEDOT:PSS system: Trp@Cu:NiO xNanoparticles were dispersed in water (5 mg / mL) and mixed with PEDOT:PSS aqueous solution (Clevios PVP AI 4083) at a volume ratio of 1:4 (mass ratio of approximately 1:10), and sonicated for 2 hours; the device was prepared in the same manner as in Example 1; the maximum EQE was 17.2%, and the T80 lifetime was 520 hours.

[0124] (2) NPB system: Trp@Cu:NiO x Nanoparticles were dispersed in chlorobenzene (5 mg / mL) and mixed with NPB chlorobenzene solution (8 mg / mL) at a volume ratio of 1:4 (mass ratio of approximately 1:8). Because NPB is a small molecule, the composite ink needs to be used within 4 hours. A 5 nm NPB layer was deposited as a supplementary layer after spin coating of the composite layer. The maximum EQE was 16.8%, and the T80 lifetime was 480 hours.

[0125] Comparative Example 1: Unmodified Cu:NiO x / TFB composite hole transport layer.

[0126] I. Preparation of Cu:NiO x Nanoparticles: Same as step (1) in Example 1, but without amino acid surface modification.

[0127] II. Preparation of Composite Ink: Unmodified Cu:NiO x Nanoparticles were dispersed in chlorobenzene at the same concentration and mixed with TFB solution. The dispersion showed obvious precipitation after standing for 12 hours.

[0128] III. Device fabrication and testing: The device fabrication and testing methods are the same as in Example 1.

[0129] Performance testing: Device turn-on voltage 2.3 V, maximum EQE 17.5%, T80 lifetime 320 hours. Thin film Rq 4.8 nm.

[0130] Comparative Example 2: Pure TFB hole transport layer.

[0131] 1. Hole transport layer was prepared by spin-coating with pure TFB solution without adding any nanoparticles.

[0132] II. The device fabrication and testing methods are the same as in Example 1.

[0133] III. Test Results: The device's turn-on voltage is 2.4 V, the maximum EQE is 15.2%, and the T80 lifespan is 80 hours.

[0134] Comparative Example 3: High Ni 3+ Content Cu:NiO x / TFB composite hole transport layer.

[0135] Cu:NiO was prepared by high-temperature calcination. x Nanoparticles enable Ni 2+ / Ni 3+ The ratio decreased, and XPS analysis showed that Ni 2+ The percentage is less than 60%. The subsequent results are the same as those of Comparative Example 1.

[0136] Performance testing: Device turn-on voltage 2.2 V, maximum EQE 16.8%, T80 lifetime 150 hours. This indicates that Ni... 2+ When the content is reduced, the antioxidant capacity decreases significantly.

[0137] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention. The above embodiments are provided only for the purpose of describing the present invention and are not intended to limit the present invention. Parts not described in detail in this specification are well-known in the art and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be covered within the scope of the present invention.

Claims

1. An antioxidant composite hole transport material with a core-shell-matrix three-level structure, characterized in that, The antioxidant composite hole transport material with a core-shell-matrix three-level structure consists of a core layer, a shell layer, and a matrix: the core layer is metal ion-doped nickel oxide nanoparticles, wherein divalent nickel accounts for no less than 80% of the total nickel content in the metal ion-doped nickel oxide nanoparticles; the shell layer is an aromatic amino acid molecular layer coated on the surface of the metal ion-doped nickel oxide nanoparticles through coordination bonds and / or hydrogen bonds; the matrix is ​​an organic hole transport material. Among them, aromatic amino acid-modified metal ion-doped nickel oxide nanoparticles are uniformly dispersed in organic hole transport materials to form a "core-shell-matrix" three-level structure; The mass ratio of the aromatic amino acid to the metal ion-doped nickel oxide nanoparticles is 1:5 to 1:20; the mass ratio of the aromatic amino acid-modified metal ion-doped nickel oxide nanoparticles to the organic hole transport material is 1:99 to 40:

60.

2. The antioxidant composite hole transport material with a core-shell-matrix three-level structure according to claim 1, characterized in that, The doped metal ions in the metal ion-doped nickel oxide nanoparticles are selected from at least one of magnesium, copper, lithium, and aluminum, and the atomic percentage of the doped metal ions in the total metal cations is 0.5% to 10%.

3. The antioxidant composite hole transport material with a core-shell-matrix three-level structure according to claim 1, characterized in that, The aromatic amino acid is selected from at least one of tryptophan, tyrosine, and histidine. The aromatic amino acid forms a coordination bond or hydrogen bond with the surface of the metal ion-doped nickel oxide nanoparticles through a carboxyl group and / or an amino group. The organic hole transport material is selected from at least one of polyvinylcarbazole, poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine), poly3,4-ethylenedioxythiophene / polystyrene sulfonate, or N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine.

4. The antioxidant composite hole transport material with a core-shell-matrix three-level structure according to claim 1, characterized in that, The particle size of the metal ion-doped nickel oxide nanoparticles is 3-15 nm.

5. A method for preparing an antioxidant composite hole transport material having a core-shell-matrix three-level structure as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Metal ion-doped nickel oxide nanoparticles are reacted with aromatic amino acids in a solvent for surface modification at a temperature of 40-80℃ for 2-24 hours to obtain aromatic amino acid-modified nanoparticles; the mass ratio of the aromatic amino acids to the metal ion-doped nickel oxide nanoparticles is 5% to 20%. (2) Disperse the aromatic amino acid-modified nanoparticles in an organic solvent to obtain a nanoparticle dispersion; (3) The nanoparticle dispersion is mixed with the organic hole transport material solution and homogenized to obtain an antioxidant composite hole transport material with a core-shell-matrix three-level structure; The homogenization process involves alternating between ultrasound and stirring, with a total processing time of 1-12 hours.

6. A composite hole transport layer, characterized in that, The antioxidant composite hole transport material having a core-shell-matrix three-level structure as described in any one of claims 1 to 4.

7. A method for preparing the composite hole transport layer according to claim 6, characterized in that, Includes the following steps: (1) Metal ion-doped nickel oxide nanoparticles were reacted with aromatic amino acids in a solvent to carry out surface modification reaction. The reaction temperature was 40-80℃ and the time was 2-24 hours to obtain aromatic amino acid-modified nanoparticles. (2) Disperse the aromatic amino acid-modified nanoparticles in an organic solvent to obtain a nanoparticle dispersion; (3) The nanoparticle dispersion is mixed with the organic hole transport material solution and homogenized to obtain an antioxidant composite hole transport material with a core-shell-matrix three-level structure; (4) The antioxidant composite hole transport material with a core-shell-matrix three-level structure is deposited on a substrate by solution processing and then annealed to form a composite hole transport layer; The annealing temperature is 100-150℃ and the time is 10-60 minutes.

8. A quantum dot light-emitting diode, comprising an anode, a cathode, and a functional layer disposed between the anode and the cathode, characterized in that, The functional layer includes the composite hole transport layer as described in claim 7.

9. The quantum dot light-emitting diode according to claim 8, characterized in that, The quantum dot light-emitting diode is a red, green, or blue QLED device.

10. The application of the antioxidant composite hole transport material with a core-shell-matrix three-level structure as described in any one of claims 1 to 4 in the preparation of optoelectronic display devices.

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