Preparation method and application of cuprous iodide cluster material based on diphenylphosphine quinoline ligand

Abstract

The invention provides a cuprous iodide cluster single crystal material as well as a preparation method and application thereof, and belongs to the technical field of luminescent materials. The cuprous iodide cluster single crystal material disclosed by the invention has a structural general formula shown in the specification. The preparation method comprises the following steps: mixing CuI, a diphenylphosphine quinoline ligand and an organic solvent to form a clear and transparent solution, and crystallizing through a room temperature volatilization method to obtain the cuprous iodide cluster single crystal material. Carrier transport is balanced and skeleton rigidity is enhanced by introducing carbazole, 3, 6-tert-butyl carbazole, phenoxazine and 9, 9-dimethyl acridine groups, exciton quenching is inhibited while an orange-red photoluminescence blank is filled, and a key material support is provided for constructing a high-performance solution processing type OLED (Organic Light Emitting Diode).

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, and particularly to cuprous iodide cluster single crystal materials, their preparation methods and applications. Specifically, it relates to a method for preparing cuprous iodide cluster single crystal materials based on donor-substituted diphenylphosphine quinoline ligands, and the application of this material in optoelectronic fields such as organic light-emitting devices (OLEDs). Background Technology

[0002] Organic-inorganic hybrid cluster materials are a class of functional materials formed by the coordination self-assembly of metal halides and organic ligands. With their rich structural diversity and excellent chemical stability, these materials have shown great application potential in fields such as electroluminescent displays, solid-state lighting, and optoelectronic sensing, and are an important material system for developing low-cost, high-performance organic light-emitting diodes (OLEDs).

[0003] In recent years, copper (I) cluster materials based on diphenylphosphine quinoline derivatives have broken through the efficiency limit of traditional fluorescent materials due to their significant thermally activated delayed fluorescence (TADF) properties, which effectively capture triplet excitons and convert them into light energy. However, these cluster materials still face key challenges when applied to solution-processed OLED devices.

[0004] On the one hand, due to the flexibility of the coordination environment at the copper (I) center, clusters are prone to structural distortion in the excited state, leading to severe nonradiative transition losses and making it difficult to achieve high-efficiency luminescence. On the other hand, existing cluster materials still have room for improvement in terms of film formation stability and carrier transport balance, resulting in significant efficiency degradation of devices at high current densities.

[0005] Therefore, the core challenge in developing practical copper-based luminescent cluster materials is to precisely design the structure of organophosphine ligands and introduce specific donor groups to synergistically regulate the energy level structure and framework rigidity of the clusters, thereby suppressing excited-state energy loss and improving device performance. Summary of the Invention

[0006] In view of this, in order to solve the technical problem of efficiency degradation of existing copper cluster materials in electroluminescence applications, this invention provides a single crystal material of cuprous iodide clusters, its preparation method and application. By introducing carbazole, 3,6-tert-butylcarbazole, phenoxazine and 9,9-dimethylacridine groups to balance carrier transport and enhance framework rigidity, it fills the gap in orange-red photoluminescence while suppressing exciton quenching, providing key material support for the construction of high-performance solution-processed OLEDs.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a cuprous iodide cluster single-crystal material having the following general structural formula: .

[0008] Secondly, the present invention provides a method for preparing a single-crystal material of cuprous iodide clusters based on diphenylphosphinequinoline ligands, comprising the following steps: Step (1): Mix CuI, diphenylphosphine quinoline ligand and organic solvent to form a clear and transparent solution; Step (2): Obtain cuprous iodide cluster single crystal material by room temperature volatilization crystallization.

[0009] Thirdly, the present invention provides the application of the above-mentioned cuprous iodide cluster single crystal material or the cuprous iodide cluster single crystal material prepared by the above preparation method as a light-emitting layer material in organic electroluminescent devices.

[0010] Fourthly, the present invention provides an electroluminescent device in which the light-emitting layer material is the cuprous iodide cluster single crystal material described above or the cuprous iodide cluster single crystal material prepared by the above preparation method.

[0011] Compared with the prior art, the present invention has the following beneficial effects: Precise spectral control: This invention achieves precise control over the electronic structure and steric hindrance of the ligand by introducing carbazole, 3,6-di-tert-butylcarbazole, phenoxazine, or 9,9-dimethylacridine donor groups into the diphenylphosphinequinoline ligand. This enables the cuprous iodide cluster single crystal material to achieve spectral tunability in the orange to red light range, filling the gap in pure copper cluster materials in the orange-red light region.

[0012] Low nonradiative transition loss: The cuprous iodide cluster single crystal material of the present invention can effectively suppress structural distortion in the excited state, significantly reduce energy loss caused by nonradiative transition, and improve luminescence efficiency.

[0013] High internal quantum efficiency: The cuprous iodide cluster single crystal material of the present invention is based on the thermally activated delayed fluorescence (TADF) mechanism, which can effectively capture and utilize triplet excitons, break through the efficiency limit of traditional fluorescent materials, and significantly improve the internal quantum efficiency of organic electroluminescent devices.

[0014] Excellent device stability: This invention optimizes the stability of the thin film morphology through the rigid design of the ligand framework, effectively alleviates the efficiency decay phenomenon of organic electroluminescent devices under high current density, and improves the stability of the device.

[0015] Adaptable to solution processing: The cuprous iodide cluster single crystal material of the present invention has both excellent thermal stability and solubility, and can be highly adapted to solution processing device fabrication processes, providing a feasible technical path for the industrial application of low-cost, high-efficiency copper (I)-based organic electroluminescent devices. Attached Figure Description

[0016] Figure 1 Photoluminescence spectra of single crystals of [CzDPPQ]2Cu4I4, [tBCzDPPQ]2Cu4I4, [PXZDPPQ]2Cu4I4, and [DMACDPPQ]2Cu4I4; Figure 2 Voltage-current density curves of electroluminescent devices fabricated from single crystals of [CzDPPQ]2Cu4I4, [tBCzDPPQ]2Cu4I4, [PXZDPPQ]2Cu4I4, and [DMACDPPQ]2Cu4I4; Figure 3 Voltage-brightness curves of electroluminescent devices fabricated from single crystals of [CzDPPQ]2Cu4I4, [tBCzDPPQ]2Cu4I4, [PXZDPPQ]2Cu4I4, and [DMACDPPQ]2Cu4I4; Figure 4 Brightness-current efficiency curves of electroluminescent devices prepared from single crystals of [CzDPPQ]2Cu4I4, [tBCzDPPQ]2Cu4I4, [PXZDPPQ]2Cu4I4, and [DMACDPPQ]2Cu4I4. Figure 5 Brightness-power efficiency curves of electroluminescent devices fabricated from single crystals of [CzDPPQ]2Cu4I4, [tBCzDPPQ]2Cu4I4, [PXZDPPQ]2Cu4I4, and [DMACDPPQ]2Cu4I4; Figure 6 Brightness-external quantum efficiency curves of electroluminescent devices prepared from single crystals of [CzDPPQ]2Cu4I4, [tBCzDPPQ]2Cu4I4, [PXZDPPQ]2Cu4I4, and [DMACDPPQ]2Cu4I4; Figure 7 Electroluminescence spectra of electroluminescent devices fabricated from single crystals of [CzDPPQ]2Cu4I4, [tBCzDPPQ]2Cu4I4, [PXZDPPQ]2Cu4I4, and [DMACDPPQ]2Cu4I4. Detailed Implementation

[0017] This invention provides a single-crystal material of cuprous iodide clusters based on diphenylphosphine quinoline ligands, having the following general structural formula: .

[0018] This invention provides a method for preparing the above-mentioned cuprous iodide cluster single crystal material based on diphenylphosphine quinoline ligands, comprising the following steps: Step (1): Mix CuI, diphenylphosphine quinoline ligand, and organic solvent to form a clear and transparent solution. In this step (1), the molar ratio of CuI to diphenylphosphine quinoline ligand is 2:1. The diphenylphosphine quinoline ligand is selected from CzDPPQ, tBCzDPPQ, PXZDPPQ, and DMACDPPQ, and its structural formula is as follows: .

[0019] The mixing process was carried out under light-protected conditions, with stirring time of 12 hours. The organic solvent was acetonitrile, ethanol, or a mixture thereof.

[0020] Step (2): Cuprous iodide cluster single crystal material is obtained by room temperature volatilization. In step (2), the ambient temperature of the room temperature volatilization method is 25 ℃ and the volatilization period is 3 days.

[0021] The application of the cuprous iodide cluster single crystal material provided by the present invention or the cuprous iodide cluster single crystal material prepared by the above preparation method as a light-emitting layer material in organic electroluminescent devices, for converting electrical energy into light energy.

[0022] This invention also provides an electroluminescent device, wherein the light-emitting layer material is the aforementioned cuprous iodide cluster single crystal material or the cuprous iodide cluster single crystal material prepared by the aforementioned preparation method. The organic electroluminescent device is constructed using a solution processing technology. The preparation method of this electroluminescent device includes: firstly, fabricating a conductive layer; then, spin-coating a hole injection layer material onto the conductive layer; spin-coating a doped light-emitting layer based on a diphenylphosphine quinoline ligand and a host material onto the hole injection layer; evaporating a hole blocking layer material onto the light-emitting layer; evaporating an electron transport layer material onto the hole blocking layer; evaporating an electron injection layer material onto the electron transport layer; and finally, evaporating a second conductive layer. Specifically: Includes the following steps: (1) Preparation of conductive anode layer: Place the glass or plastic substrate, which has been cleaned with deionized water, into a vacuum evaporation apparatus with a vacuum degree of 1×10⁻⁶. -6 mbar, the evaporation rate is set to 0.1-0.3 nm / s, and the material is indium tin oxide (ITO) evaporated on glass or plastic substrate to form an anolyte conductive layer with a thickness of 1-100 nm.

[0023] (2) Preparation of hole injection layer: The hole injection layer was spin-coated on the anodic conductive layer with a spin coating thickness of 20 nm. The hole injection layer material was poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS). Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) and deionized water were mixed in a 1:1 ratio and spin-coated on a pre-cleaned ITO glass substrate at 2000 rpm. Then it was dried at 120 °C for 15 minutes.

[0024] (3) Fabrication of the luminescent layer: The luminescent layer is spin-coated onto the hole transport layer, with a spin-coating thickness of 25 nm. The light-emitting layer material is a mixture of cuprous iodide cluster single crystal material based on diphenylphosphine quinoline ligand and the host material. The cuprous iodide cluster single crystal material is the above-mentioned cuprous iodide cluster single crystal material or the cuprous iodide cluster single crystal material prepared by the above preparation method.

[0025] The main material is selected from 9,9'-(1,3-phenyl)di-9H-carbazole (mCP), bis-4-(N-carbazolylphenyl)phenylphosphine oxide (BCPO), 4,4-di(9-carbazole)biphenyl (CBP), 4,4'-bis(9H-carbazol-9-yl)-2,2'-dimethylbiphenyl (CDBP), (4-(9H-carbazol-9-yl)-2-methylphenyl)diphenylphosphine oxide (CPPOM), 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9h-carbazole (CzSi), or di[2-((oxo)diphenylphosphine)phenyl] ether (DPEPO) or polyvinylcarbazole (PVK); preferably 9,9'-(1,3-phenyl)di-9H-carbazole (mCP). (4) Preparation of hole blocking layer: The hole blocking layer is deposited on the light-emitting layer by vapor deposition, and the deposition thickness is 10 nm. The hole-blocking layer material is di[2-((oxo)diphenylphosphino)phenyl] ether (DPEPO); (5) Preparation of electron transport layer: The electron transport layer is deposited on the hole blocking layer by vapor deposition with a thickness of 30 nm. The electron transport layer material is 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]dipyridine (TmPyPB).

[0026] (6) Preparation of electron injection layer: The electron injection layer is deposited on the electron transport layer by vapor deposition with a thickness of 1 nm. The electron injection layer material is selected from LiF.

[0027] (7) Prepare the cathode conductive layer and encapsulate it to obtain an organic-inorganic hybrid copper cluster electroluminescent device. The cathode conductive layer is deposited on the electron injection layer with a deposition thickness of 100 nm.

[0028] The present invention also provides an electroluminescent device for use in full-color displays, lighting panels or flexible optoelectronic devices.

[0029] The technical solution of the present invention will be clearly and thoroughly explained below with reference to specific experimental procedures.

[0030] 1. Take 2 mmol of CuI, 1 mmol of organophosphine ligand, and an appropriate amount of organic solvent, mix them, and obtain a cuprous iodide cluster single crystal material based on diphenylphosphine quinoline ligand by room temperature volatilization. The organophosphorus ligand structure is as follows:

[0031] The organic solvent is ethanol.

[0032] (1) Synthesis of CzDPPQ: 1 mmol of 6-bromo-2-chloroquinoline, 2 mmol of carbazole, 2 mmol of sodium tert-butoxide, and 1.5 mmol of tri-tert-butylphosphine were dissolved in 10 mL of toluene and stirred at 100 °C for 12 h under an argon atmosphere. The system was then allowed to cool naturally to room temperature, and the reaction was terminated by adding water. The mixture was extracted with ethyl acetate and purified by column chromatography. Subsequently, under an argon atmosphere, 1 mL of n-butyllithium was added dropwise at 0 °C to 5 mL of a 2.5 mmol diphenylphosphine tetrahydrofuran solution. After reacting at the same temperature for 0.5 h, the resulting solution was slowly added to 0.5 mmol of a 6-carbazole-2-chloroquinoline tetrahydrofuran solution, and stirred at 0 °C for 2 h. The system was then allowed to warm naturally to room temperature, the reaction was quenched with water, extracted with dichloromethane, and purified by column chromatography to obtain CzDPPQ.

[0033] (2) Synthesis of [CzDPPQ]2Cu4I4: Take 2 mmol of CuI, 1 mmol of CzDPPQ, and 6 mL of acetonitrile and place them in a small beaker. Mix them by ultrasonic stirring to form a clear and transparent solution. Cover with plastic wrap, poke 10-20 holes, and allow to evaporate at room temperature for 3 days to obtain [CzDPPQ]2Cu4I4 single crystals with the following structural formula:

[0034] (3) Synthesis of tBCzDPPQ: 1 mmol of 6-bromo-2-chloroquinoline, 2 mmol of 3,6-di-tert-butylcarbazole, 2 mmol of sodium tert-butoxide, and 1.5 mmol of tri-tert-butylphosphine were dissolved in 10 mL of toluene and stirred at 100 °C for 12 h under an argon atmosphere. The system was then allowed to cool naturally to room temperature, and the reaction was terminated by adding water. The mixture was extracted with ethyl acetate and purified by column chromatography. Subsequently, under an argon atmosphere, 1 mL of n-butyllithium was added dropwise at 0 °C to 5 mL of a 2.5 mmol diphenylphosphine tetrahydrofuran solution. After reacting at the same temperature for 0.5 h, the resulting solution was slowly added to 0.5 mmol of a 6-tert-butylcarbazole-2-chloroquinoline tetrahydrofuran solution, and stirred at 0 °C for 2 h. The system was then allowed to warm naturally to room temperature, the reaction was quenched with water, extracted with dichloromethane, and purified by column chromatography to obtain tBCzDPPQ.

[0035] (4) Synthesis of [tBCzDPPQ]2Cu4I4: Take 2 mmol of CuI, 1 mmol of tBCzDPPQ, and 6 mL of ethanol and place them in a small beaker. Mix them by ultrasonic stirring to form a clear and transparent solution. Cover with plastic wrap, poke 10-20 holes, and allow to evaporate at room temperature for 3 days to obtain [tBCzDPPQ]2Cu4I4 single crystals with the following structural formula:

[0036] (5) Synthesis of PXZDPPQ: 1 mmol of 6-bromo-2-chloroquinoline, 2 mmol of phenoxazine, 2 mmol of sodium tert-butoxide, and 1.5 mmol of tri-tert-butylphosphine were dissolved in 10 mL of toluene and stirred at 100 °C for 12 h under an argon atmosphere. The system was then allowed to cool naturally to room temperature, and the reaction was terminated by adding water. The mixture was extracted with ethyl acetate and purified by column chromatography. Subsequently, under an argon atmosphere, 1 mL of n-butyllithium was added dropwise at 0 °C to 5 mL of a 2.5 mmol diphenylphosphine tetrahydrofuran solution. After reacting at the same temperature for 0.5 h, the resulting solution was slowly added to 0.5 mmol of a 6-phenoxazine-2-chloroquinoline tetrahydrofuran solution, and stirred at 0 °C for 2 h. The system was then allowed to warm naturally to room temperature, the reaction was quenched with water, extracted with dichloromethane, and purified by column chromatography to obtain PXZDPPQ.

[0037] (6) Synthesis of [PXZDPPQ]2Cu4I4: A mixed solution of 2 mmol CuI, 1 mmol PXZDPPQ, 6 mL acetonitrile, and ethanol was placed in a small beaker and ultrasonically stirred to form a clear and transparent solution. The beaker was covered with plastic wrap, and 10-20 holes were punched in it. After evaporation at room temperature for 3 days, [PXZDPPQ]2Cu4I4 single crystals were obtained, with the following structural formula:

[0038] (7) Synthesis of DMACDPPQ: 1 mmol of 6-bromo-2-chloroquinoline, 2 mmol of 9,9-dimethylacridine, 2 mmol of sodium tert-butoxide, and 1.5 mmol of tri-tert-butylphosphine were dissolved in 10 mL of toluene and stirred at 100 °C for 12 h under an argon atmosphere. The system was then allowed to cool naturally to room temperature, and the reaction was terminated by adding water. The mixture was extracted with ethyl acetate and purified by column chromatography. Subsequently, under an argon atmosphere, 1 mL of n-butyllithium was added dropwise at 0 °C to 5 mL of a 2.5 mmol diphenylphosphine tetrahydrofuran solution. After reacting at the same temperature for 0.5 h, the resulting solution was slowly added to 0.5 mmol of a 5 mL tetrahydrofuran solution of 6-(9,9-dimethylacridine)-2-chloroquinoline, and stirred at 0 °C for 2 h. The system was then allowed to warm naturally to room temperature, the reaction was quenched with water, extracted with dichloromethane, and purified by column chromatography to obtain DMACDPPQ.

[0039] (8) Synthesis of [DMACDPPQ]2Cu4I4: Take 2 mmol of CuI, 1 mmol of DMACDPPQ, and 6 mL of ethanol and place them in a small beaker. Mix them by ultrasonic stirring to form a clear and transparent solution. Cover with plastic wrap, poke 10-20 holes, and allow to evaporate at room temperature for 3 days to obtain [DMACDPPQ]2Cu4I4 single crystals, with the following structural formula:

[0040] 2. Applications and methods of organic-inorganic hybrid iodide ketone cluster single crystal materials in electroluminescent devices: (1) Preparation of conductive anode layer: Place the glass or plastic substrate, which has been cleaned with deionized water, into a vacuum evaporation apparatus with a vacuum degree of 1×10⁻⁶. -6 The deposition rate was set to 0.3 nm / s, and an indium tin oxide (ITO) anolyte conductive layer with a thickness of 50 nm was deposited on a glass or plastic substrate. (2) Preparation of hole injection layer: The hole injection layer was spin-coated on the anolyte conductive layer with a thickness of 20 nm. The hole injection layer material was poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS). Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) and deionized water were mixed in a 1:1 ratio and spin-coated on a pre-cleaned ITO glass substrate at 2000 rpm. Then, it was dried at 120 °C for 15 minutes. (3) Preparation of the light-emitting layer: The light-emitting layer is spin-coated on the hole transport layer with a spin-coating thickness of 25 nm; the light-emitting layer material is a doped mixture of the cuprous iodide cluster single crystal material based on the above-mentioned diphenylphosphine quinoline ligand and the host material. The main material is selected from 9,9'-(1,3-phenyl)bis-9H-carbazole (mCP), bis-4-(N-carbazole-phenyl)phenylphosphine oxide (BCPO), 4,4-bis(9-carbazole)biphenyl (CBP), 4,4'-bis(9H-carbazole-9-yl)-2,2'-dimethylbiphenyl (CDBP), (4-(9H-carbazole-9-yl)-2-methylphenyl)diphenylphosphine oxide (CPPOM), 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9h-carbazole (CzSi), or di[2-((oxo)diphenylphosphine)phenyl] ether (DPEPO) or polyvinylcarbazole (PVK); preferably 4,4-bis(9-carbazole)biphenyl (CBP).

[0041] (4) Preparation of hole blocking layer: The hole blocking layer is deposited on the light-emitting layer by vapor deposition, and the deposition thickness is 10 nm; the hole blocking layer material is di[2-((oxo)diphenylphosphino)phenyl] ether (DPEPO).

[0042] (5) Preparation of electron transport layer: The electron transport layer is deposited on the hole blocking layer by vapor deposition with a thickness of 30 nm; the electron transport layer material is 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]dipyridine (TmPyPB).

[0043] (6) Preparation of electron injection layer: The electron injection layer is deposited on the electron transport layer by evaporation, and the evaporation thickness is 1 nm; the electron injection layer material is selected from LiF.

[0044] (7) Preparation of cathode conductive layer: Encapsulation to obtain organic-inorganic hybrid iodide ketone cluster electroluminescent device; the cathode conductive layer is deposited on the electron injection layer with a deposition thickness of 100 nm.

[0045] The invention, developed through molecular design, reveals that cuprous iodide clusters possess advantages such as rich diversity in excited-state composition and environmental friendliness. Strong electron-donating groups on ligands can significantly improve the electrical properties of materials, enhance solution processability, and regulate the proportion of excited states; the strong interaction between ligands and Cu4I4 can induce electronic transitions. This invention employs an octahedral Cu4I4 cluster core to enhance the overall rigidity of the molecule, and the significant steric hindrance generated by the diphenylphosphine group effectively limits the energy loss from nonradiative transitions. By strengthening the charge transfer interaction between the intramolecular donor and acceptor, deep modulation of the emission spectrum is achieved, resulting in high-efficiency electroluminescent devices (such as…). Figure 2-6 This invention provides a cuprous iodide cluster based on donor-modified diphenylphosphinequinoline, which utilizes an asymmetric single-donor modification strategy to regulate the excited-state composition and enhance ligand-associated charge transfer (LCT) and metal-to-ligand charge transfer (MLCT) interactions. This asymmetric structure effectively prevents intermolecular stacking and inhibits aggregation-induced quenching. The diphenylphosphinequinoline functional group serves as the core acceptor and "anchor," and its coordination sites can immobilize the Cu4I4 cluster nucleus. By introducing strong donor units at specific sites on the quinoline, energy level regulation and spectral redshift (e.g., ...) are achieved. Figure 1 and Figure 7 This fills the gap in the application of pure copper complexes in the field of orange-red photoluminescence.

[0046] Compared with existing technologies, this invention has the following technical advantages: (1) This invention utilizes the octahedral Cu4I4 cluster core and diphenylphosphine group to generate a large steric hindrance, effectively limiting nonradiative transition losses and increasing the maximum EQE of the device to 43.7%. This value is significantly higher than that of Au(I)-Cu(I) clusters using NHC ligands. [1] (EQE 20.8%), which also significantly surpasses the PtAu2 cluster based on NAI modification. [2] (EQE 16.7%) and alloyed Au-Cu nanoclusters [3] (EQE 15.43%). This demonstrates the remarkable ability of the diphenylphosphinequinoline system to capture triplet excitons and suppress energy loss.

[0047] (2) Existing research often enhances spin-orbit coupling (SOC) efficiency by introducing noble metals (such as Au, Pt). This differs from designs that rely on heterometallic doping or heavy metal effects in the literature. [1] [2][3] This invention utilizes an asymmetric single-donor modification strategy to control the excited state, achieving a precise redshift from yellow-green to orange-red light using only a pure copper system (e.g., Figure 1 and Figure 7 This not only fills the gap in the application of pure copper complexes in the field of orange-red photoluminescence, but also demonstrates stronger competitiveness in the balance between color purity and efficiency.

[0048] (3) This invention uses diphenylphosphinequinoline as the core acceptor and "anchor point," enhancing carrier injection balance. Compared with previously reported complex Au-Cu alloying processes or Pt-Au cluster assembly strategies, this method achieves better results. [1] [2][3] The donor-modified cuprous iodide clusters provided by this invention have a simpler preparation process. Their asymmetric structure can effectively suppress aggregation-induced quenching and significantly alleviate efficiency degradation under high current density, laying a solid foundation for realizing low-cost, high-performance solution-processed OLEDs.

[0049] (4) The polarization of specific units in the ligand enhances the carrier injection efficiency, which reduces the turn-on voltage of the spin-coated electroluminescent device prepared based on the material of the present invention to about 4V, effectively reducing the overall power consumption of the device.

[0050] (5) This invention utilizes abundant copper metal to replace scarce precious metals (such as gold and silver), has a simple synthesis route, low raw material cost and easy control, high yield, and has excellent prospects for industrial application and environmental benefits.

[0051] Example 1 In Ar atmosphere, 1 mmol of 6-bromo-2-chloroquinoline, 2 mmol of carbazole, 2 mmol of sodium tert-butoxide, and 1.5 mmol of tri-tert-butylphosphine were dissolved in 10 mL of toluene and stirred at 100 °C for 12 h under an argon atmosphere. The system was then allowed to cool naturally to room temperature, and the reaction was terminated by adding water. The mixture was extracted with ethyl acetate and purified by column chromatography. Subsequently, under an argon atmosphere, 1 mL of n-butyllithium was added dropwise at 0 °C to 5 mL of a 2.5 mmol diphenylphosphine tetrahydrofuran solution. After reacting at the same temperature for 0.5 h, the resulting solution was slowly added to 5 mL of a 0.5 mmol 6-carbazole-2-chloroquinoline tetrahydrofuran solution, and stirred at 0 °C for 2 h. The system was then allowed to warm naturally to room temperature, the reaction was quenched with water, extracted with dichloromethane, and purified by column chromatography to obtain CzDPPQ.

[0052] Take 2 mmol of CuI, 1 mmol of CzDPPQ and 6 mL of acetonitrile and place them in a small beaker. Mix them by ultrasonic stirring to form a clear and transparent solution. Cover with plastic wrap, poke 10-20 holes, and allow to evaporate at room temperature for 3 days to obtain [CzDPPQ]2Cu4I4 single crystal.

[0053] The obtained [CzDPPQ]2Cu4I4 was subjected to fluorescence spectroscopy, and the test spectrum is shown below. Figure 1 As shown.

[0054] Electroluminescent devices were prepared using a mixture of [CzDPPQ]2Cu4I4 and CBP as the light-emitting layer material, as follows: (1) Preparation of conductive anode layer: Place the glass or plastic substrate, which has been cleaned with deionized water, into a vacuum evaporation apparatus with a vacuum degree of 1×10⁻⁶. -6 The deposition rate was set to 0.3 nm / s, and an indium tin oxide (ITO) anolyte conductive layer with a thickness of 50 nm was deposited on a glass or plastic substrate. (2) Preparation of hole injection layer: The hole injection layer was spin-coated on the anolyte conductive layer with a thickness of 20 nm. The hole injection layer material was poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS). Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) and deionized water were mixed in a 1:1 ratio and spin-coated on a pre-cleaned ITO glass substrate at 2000 rpm. Then, it was dried at 120 °C for 15 minutes. (3) Preparation of the light-emitting layer: The light-emitting layer is spin-coated on the hole transport layer with a thickness of 25 nm; the material of the light-emitting layer is a doped mixture of [CzDPPQ]2Cu4I4 and CBP host material.

[0055] (4) Preparation of hole blocking layer: The hole blocking layer is deposited on the light-emitting layer by vapor deposition, and the deposition thickness is 10 nm; the hole blocking layer material is di[2-((oxo)diphenylphosphino)phenyl] ether (DPEPO).

[0056] (5) Preparation of electron transport layer: The electron transport layer is deposited on the hole blocking layer by vapor deposition with a thickness of 30 nm; the electron transport layer material is 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]dipyridine (TmPyPB).

[0057] (6) Preparation of electron injection layer: The electron injection layer is deposited on the electron transport layer by evaporation, and the evaporation thickness is 1 nm; the electron injection layer material is selected from LiF.

[0058] (7) Preparation of cathode conductive layer: Encapsulation to obtain organic-inorganic hybrid iodide ketone cluster electroluminescent device; the cathode conductive layer is deposited on the electron injection layer with a deposition thickness of 100 nm.

[0059] In this embodiment, the structure of the electroluminescent device is: ITO / PEDOT:PSS(40nm) / [CzDPPQ]2Cu4I4:CBP(20%)20nm / TmPyPB(30nm) / LiF(1nm) / Al.

[0060] Example 2 In Ar atmosphere, 1 mmol of 6-bromo-2-chloroquinoline, 2 mmol of 3,6-di-tert-butylcarbazole, 2 mmol of sodium tert-butoxide, and 1.5 mmol of tri-tert-butylphosphine were dissolved in 10 mL of toluene and stirred at 100 °C for 12 h. The system was then allowed to cool naturally to room temperature, and the reaction was terminated by adding water. The mixture was extracted with ethyl acetate and purified by column chromatography. Subsequently, under Ar atmosphere, 1 mL of n-butyllithium was added dropwise at 0 °C to 5 mL of a 2.5 mmol diphenylphosphine tetrahydrofuran solution. After reacting at the same temperature for 0.5 h, the resulting solution was slowly added to 0.5 mmol of a 5 mL tetrahydrofuran solution of 6-tert-butylcarbazole-2-chloroquinoline, and stirred at 0 °C for 2 h. The system was then allowed to warm naturally to room temperature, the reaction was quenched with water, extracted with dichloromethane, and purified by column chromatography to obtain tBCzDPPQ.

[0061] Take 2 mmol of CuI, 1 mmol of tBCzDPPQ and 6 mL of ethanol and place them in a small beaker. Mix them by ultrasonic stirring to form a clear and transparent solution. Cover with plastic wrap, poke 10-20 holes, and allow to evaporate at room temperature for 3 days to obtain [tBCzDPPQ]2Cu4I4 single crystal.

[0062] The obtained [tBCzDPPQ]2Cu4I4 was subjected to fluorescence spectroscopy, and the test spectrum is shown below. Figure 1 As shown.

[0063] Electroluminescent devices were prepared using the mixture of [tBCzDPPQ]2Cu4I4 and CBP as the light-emitting layer material, as follows: (1) Preparation of conductive anode layer: Place the glass or plastic substrate, which has been cleaned with deionized water, into a vacuum evaporation apparatus with a vacuum degree of 1×10⁻⁶. -6 The deposition rate was set to 0.3 nm / s, and an indium tin oxide (ITO) anolyte conductive layer with a thickness of 50 nm was deposited on a glass or plastic substrate. (2) Preparation of hole injection layer: The hole injection layer was spin-coated on the anolyte conductive layer with a thickness of 20 nm. The hole injection layer material was poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS). Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) and deionized water were mixed in a 1:1 ratio and spin-coated on a pre-cleaned ITO glass substrate at 2000 rpm. Then, it was dried at 120 °C for 15 minutes. (3) Preparation of the light-emitting layer: The light-emitting layer is spin-coated on the hole transport layer with a thickness of 25 nm; the light-emitting layer material is a doped mixture of [tBCzDPPQ]2Cu4I4 and CBP host material.

[0064] (4) Preparation of hole blocking layer: The hole blocking layer is deposited on the light-emitting layer by vapor deposition, and the deposition thickness is 10 nm; the hole blocking layer material is di[2-((oxo)diphenylphosphino)phenyl] ether (DPEPO).

[0065] (5) Preparation of electron transport layer: The electron transport layer is deposited on the hole blocking layer by vapor deposition with a thickness of 30 nm; the electron transport layer material is 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]dipyridine (TmPyPB).

[0066] (6) Preparation of electron injection layer: The electron injection layer is deposited on the electron transport layer by evaporation, and the evaporation thickness is 1 nm; the electron injection layer material is selected from LiF.

[0067] (7) Preparation of cathode conductive layer: Encapsulation to obtain organic-inorganic hybrid iodide ketone cluster electroluminescent device; the cathode conductive layer is deposited on the electron injection layer with a deposition thickness of 100 nm.

[0068] In this embodiment, the structure of the electroluminescent device is: ITO / PEDOT:PSS(40nm) / [tBCzDPPQ]2Cu4I4:CBP(20%)20nm / TmPyPB(30nm) / LiF(1nm) / Al.

[0069] Example 3 In Ar atmosphere, 1 mmol of 6-bromo-2-chloroquinoline, 2 mmol of phenoxazine, 2 mmol of sodium tert-butoxide, and 1.5 mmol of tri-tert-butylphosphine were dissolved in 10 mL of toluene and stirred at 100 °C for 12 h under an argon atmosphere. The system was then allowed to cool naturally to room temperature, and the reaction was terminated by adding water. The mixture was extracted with ethyl acetate and purified by column chromatography. Subsequently, under an argon atmosphere, 1 mL of n-butyllithium was added dropwise at 0 °C to 5 mL of a 2.5 mmol diphenylphosphine tetrahydrofuran solution. After reacting at the same temperature for 0.5 h, the resulting solution was slowly added to 0.5 mmol of a 6-phenoxazine-2-chloroquinoline tetrahydrofuran solution, and stirred at 0 °C for 2 h. The system was then allowed to warm naturally to room temperature, the reaction was quenched with water, extracted with dichloromethane, and purified by column chromatography to obtain PXZDPPQ.

[0070] Take 2 mmol of CuI, 1 mmol of PXZDPPQ, 6 mL of acetonitrile and ethanol mixed solution and place them in a small beaker. Stir the mixture with sonication to form a clear and transparent solution. Cover with plastic wrap, poke 10-20 holes and allow it to evaporate at room temperature for 3 days to obtain [PXZDPPQ]2Cu4I4 single crystal.

[0071] The obtained [PXZDPPQ]2Cu4I4 was subjected to fluorescence spectroscopy, and the test spectrum is shown below. Figure 1 As shown.

[0072] Electroluminescent devices were fabricated using a mixture of [PXZDPPQ]2Cu4I4 and CBP as the light-emitting layer material, as follows: (1) Preparation of conductive anode layer: Place the glass or plastic substrate, which has been cleaned with deionized water, into a vacuum evaporation apparatus with a vacuum degree of 1×10⁻⁶. -6 The deposition rate was set to 0.3 nm / s, and an indium tin oxide (ITO) anolyte conductive layer with a thickness of 50 nm was deposited on a glass or plastic substrate. (2) Preparation of hole injection layer: The hole injection layer was spin-coated on the anolyte conductive layer with a thickness of 20 nm. The hole injection layer material was poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS). Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) and deionized water were mixed in a 1:1 ratio and spin-coated on a pre-cleaned ITO glass substrate at 2000 rpm. Then, it was dried at 120 °C for 15 minutes. (3) Preparation of the light-emitting layer: The light-emitting layer is spin-coated on the hole transport layer with a thickness of 25 nm; the light-emitting layer material is a doped mixture of [PXZDPPQ]2Cu4I4 and CBP host material.

[0073] (4) Preparation of hole blocking layer: The hole blocking layer is deposited on the light-emitting layer by vapor deposition, and the deposition thickness is 10 nm; the hole blocking layer material is di[2-((oxo)diphenylphosphino)phenyl] ether (DPEPO).

[0074] (5) Preparation of electron transport layer: The electron transport layer is deposited on the hole blocking layer by vapor deposition with a thickness of 30 nm; the electron transport layer material is 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]dipyridine (TmPyPB).

[0075] (6) Preparation of electron injection layer: The electron injection layer is deposited on the electron transport layer by evaporation, and the evaporation thickness is 1 nm; the electron injection layer material is selected from LiF.

[0076] (7) Preparation of cathode conductive layer: Encapsulation to obtain organic-inorganic hybrid iodide ketone cluster electroluminescent device; the cathode conductive layer is deposited on the electron injection layer with a deposition thickness of 100 nm.

[0077] In this embodiment, the structure of the electroluminescent device is: ITO / PEDOT:PSS(40nm) / [PXZDPPQ]2Cu4I4:CBP(20%)20nm / TmPyPB(30nm) / LiF(1nm) / Al.

[0078] Example 4 In Ar atmosphere, 1 mmol of 6-bromo-2-chloroquinoline, 2 mmol of 9,9-dimethylacridine, 2 mmol of sodium tert-butoxide, and 1.5 mmol of tri-tert-butylphosphine were dissolved in 10 mL of toluene and stirred at 100 °C for 12 h. The system was then allowed to cool naturally to room temperature, and the reaction was terminated by adding water. The mixture was extracted with ethyl acetate and purified by column chromatography. Subsequently, under Ar atmosphere, 1 mL of n-butyllithium was added dropwise at 0 °C to 5 mL of a 2.5 mmol diphenylphosphine tetrahydrofuran solution. After reacting at the same temperature for 0.5 h, the resulting solution was slowly added to 0.5 mmol of a 5 mL tetrahydrofuran solution of 6-(9,9-dimethylacridine)-2-chloroquinoline, and stirred at 0 °C for 2 h. The system was then allowed to warm naturally to room temperature, the reaction was quenched with water, extracted with dichloromethane, and purified by column chromatography to obtain DMACDPPQ.

[0079] Take 2 mmol of CuI, 1 mmol of DMACDPPQ and 6 mL of ethanol and place them in a small beaker. Mix them by ultrasonic stirring to form a clear and transparent solution. Cover with plastic wrap, poke 10-20 holes, and allow to evaporate at room temperature for 3 days to obtain [DMACDPPQ]2Cu4I4 single crystal.

[0080] The fluorescence spectrum of the obtained [DMACDPPQ]2Cu4I4 was measured, and the test spectrum is shown below. Figure 1 As shown.

[0081] Electroluminescent devices were fabricated using a mixture of [DMACDPPQ]2Cu4I4 and CBP as the light-emitting layer material, as follows: (1) Preparation of conductive anode layer: Place the glass or plastic substrate, which has been cleaned with deionized water, into a vacuum evaporation apparatus with a vacuum degree of 1×10⁻⁶. -6 The deposition rate was set to 0.3 nm / s, and an indium tin oxide (ITO) anolyte conductive layer with a thickness of 50 nm was deposited on a glass or plastic substrate. (2) Preparation of hole injection layer: The hole injection layer was spin-coated on the anolyte conductive layer with a thickness of 20 nm. The hole injection layer material was poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS). Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) and deionized water were mixed in a 1:1 ratio and spin-coated on a pre-cleaned ITO glass substrate at 2000 rpm. Then, it was dried at 120 °C for 15 minutes. (3) Preparation of the light-emitting layer: The light-emitting layer is spin-coated on the hole transport layer with a thickness of 25 nm; the light-emitting layer material is a doped mixture of [DMACDPPQ]2Cu4I4 and CBP host material.

[0082] (4) Preparation of hole blocking layer: The hole blocking layer is deposited on the light-emitting layer by vapor deposition, and the deposition thickness is 10 nm; the hole blocking layer material is di[2-((oxo)diphenylphosphino)phenyl] ether (DPEPO).

[0083] (5) Preparation of electron transport layer: The electron transport layer is deposited on the hole blocking layer by vapor deposition with a thickness of 30 nm; the electron transport layer material is 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]dipyridine (TmPyPB).

[0084] (6) Preparation of electron injection layer: The electron injection layer is deposited on the electron transport layer by evaporation, and the evaporation thickness is 1 nm; the electron injection layer material is selected from LiF.

[0085] (7) Preparation of cathode conductive layer: Encapsulation to obtain organic-inorganic hybrid iodide ketone cluster electroluminescent device; the cathode conductive layer is deposited on the electron injection layer with a deposition thickness of 100 nm.

[0086] In this embodiment, the structure of the electroluminescent device is: ITO / PEDOT:PSS(40nm) / [DMACDPPQ]2Cu4I4:CBP(20%)20nm / TmPyPB(30nm) / LiF(1nm) / Al.

[0087] Comparative Example 1 Electroluminescent devices were fabricated using a mixture of [TMeOPP]4Cu4I4 and CBP as the light-emitting layer material, as follows: (1) Preparation of conductive anode layer: Place the glass or plastic substrate, which has been cleaned with deionized water, into a vacuum evaporation apparatus with a vacuum degree of 1×10⁻⁶. -6 The deposition rate was set to 0.3 nm / s, and an indium tin oxide (ITO) anolyte conductive layer with a thickness of 50 nm was deposited on a glass or plastic substrate. (2) Preparation of hole injection layer: The hole injection layer was spin-coated on the anolyte conductive layer with a thickness of 20 nm. The hole injection layer material was poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS). Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) and deionized water were mixed in a 1:1 ratio and spin-coated on a pre-cleaned ITO glass substrate at 2000 rpm. Then, it was dried at 120 °C for 15 minutes. (3) Preparation of the light-emitting layer: The light-emitting layer is spin-coated on the hole transport layer with a thickness of 25 nm; the material of the light-emitting layer is a doped mixture of [TMeOPP]4Cu4I4 and CBP host material.

[0088] (4) Preparation of hole blocking layer: The hole blocking layer is deposited on the light-emitting layer by vapor deposition, and the deposition thickness is 10 nm; the hole blocking layer material is di[2-((oxo)diphenylphosphino)phenyl] ether (DPEPO).

[0089] (5) Preparation of electron transport layer: The electron transport layer is deposited on the hole blocking layer by vapor deposition with a thickness of 30 nm; the electron transport layer material is 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]dipyridine (TmPyPB).

[0090] (6) Preparation of electron injection layer: The electron injection layer is deposited on the electron transport layer by evaporation, and the evaporation thickness is 1 nm; the electron injection layer material is selected from LiF.

[0091] (7) Preparation of cathode conductive layer: Encapsulation to obtain organic-inorganic hybrid iodide ketone cluster electroluminescent device; the cathode conductive layer is deposited on the electron injection layer with a deposition thickness of 100 nm.

[0092] The structural formula of [TMeOPP]4Cu4I4 is as follows: .

[0093] The above description is merely a preferred embodiment of the present invention. However, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention should be covered within the scope of protection of the present invention.

Claims

1. A single-crystal material of cuprous iodide clusters based on diphenylphosphine quinoline ligands, characterized in that, It has the following general structural formula: 。 2. A method for preparing cuprous iodide cluster single-crystal materials based on diphenylphosphine quinoline ligands, characterized in that, Includes the following steps: Step (1): Mix CuI, diphenylphosphine quinoline ligand and organic solvent to form a clear and transparent solution; Step (2): Obtain cuprous iodide cluster single crystal material by room temperature volatilization crystallization.

3. The method for preparing a single-crystal material of cuprous iodide clusters based on diphenylphosphine quinoline ligands according to claim 2, characterized in that, In step (1), the molar ratio of CuI to diphenylphosphine quinoline ligand is 2:

1.

4. The method for preparing a single-crystal material of cuprous iodide clusters based on diphenylphosphine quinoline ligands according to claim 2, characterized in that, The diphenylphosphine quinoline ligand is selected from one of CzDPPQ, tBCzDPPQ, PXZDPPQ, and DMACDPPQ, and has the following structural formula: 。 5. The method for preparing a single-crystal material of cuprous iodide clusters based on diphenylphosphine quinoline ligands according to claim 2, characterized in that, In step (1), the mixing process is carried out under light-protected conditions, and the stirring time is 12 hours.

6. The method for preparing a single-crystal material of cuprous iodide clusters based on diphenylphosphine quinoline ligands according to claim 2, characterized in that, In step (2), the ambient temperature of the room temperature evaporation method is 25 °C and the evaporation period is 3 days.

7. A method for preparing a single-crystal material of cuprous iodide clusters based on diphenylphosphine quinoline ligands according to any one of claims 2-6, characterized in that, The organic solvent is acetonitrile, ethanol, or a mixture thereof.

8. The application of the cuprous iodide cluster single crystal material according to claim 1 or the cuprous iodide cluster single crystal material prepared by any one of claims 2-7 as a light-emitting layer material in organic electroluminescent devices.

9. An electroluminescent device, characterized in that, The luminescent layer material is the cuprous iodide cluster single crystal material as described in claim 1 or the cuprous iodide cluster single crystal material prepared by any one of claims 2-7.

10. An electroluminescent device according to claim 9, characterized in that, Used in full-color displays, lighting panels, or flexible optoelectronic devices.

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