Quantum dot electrolyte light-emitting device and preparation method thereof

Abstract

The application discloses a quantum dot electrolyte light-emitting device and a preparation method thereof. The device comprises a substrate and a light-emitting laminated structure sequentially arranged on the substrate, wherein the light-emitting laminated structure comprises a cathode, an electron transport layer, a polymer barrier layer, a quantum dot electrolyte light-emitting layer, a hole transport layer, a hole injection layer and an anode. The quantum dot electrolyte light-emitting layer comprises quantum dot light-emitting materials and ionic liquid. During operation, the anion and cation in the ionic liquid form a double electric layer at the interface under the action of an electric field, thereby reducing the carrier injection barrier and improving the charge injection and transmission. The polymer barrier layer arranged between the electron transport layer and the light-emitting layer inhibits excessive electron injection and realizes the balanced recombination of electrons and holes. Under the double regulation of the ionic liquid and the polymer barrier layer, the device solves the problem of electron leakage caused by the unbalanced charge injection and transmission, and improves the light-emitting efficiency and working life.

Description

Technical Field

[0001] This invention relates to the field of semiconductor light-emitting technology, and in particular to a quantum dot electrolyte light-emitting device and its preparation method. Background Technology

[0002] In the exploration of next-generation display, lighting, and optical communication technologies, quantum dot (QD)-based electroluminescent (EL) devices have become a highly promising technological route due to their ultra-narrow full width at half maximum (FWHM), size-tunable emission wavelength, high photoluminescence quantum yield, and excellent color purity. Among these, quantum dot light-emitting diodes (QD-LEDs) and quantum dot luminescent electrochemical cells (QD-LECs) are the two mainstream technologies. However, QD-LECs, due to the lack of an electron / hole blocking layer and their simple device structure, are prone to carrier injection and transport imbalances, leading to a sharp increase in non-radiative recombination. Consequently, their external quantum efficiency (EQE) and lifetime are generally low, typically below 1000 cd / m². -2 At initial brightness, the highest EQE is often below 1.0%, and the T50 lifetime is less than 1.0 hour; with the continuous optimization of the intrinsic characteristics of quantum dots and device structure, the EQE of QD-LEDs has exceeded 20%, and red and green QD-LEDs have achieved EQE at 1000 cd / m². -2 The T95 lifetime (the time required for brightness to decay to 95% of the initial value) of blue QD-LEDs exceeds 5,000 hours and 10,000 hours respectively. However, due to the wide bandgap characteristics and carrier recombination imbalance, the stability of blue QD-LEDs remains a key bottleneck that needs to be overcome.

[0003] Quantum dot electrolyte light-emitting devices (QE-LEDs) are an emerging type of electroluminescent (EL) device. They utilize the introduction of ionic liquids into the light-emitting layer to form a quantum dot electrolyte (QE). Under the influence of an electric field, cations and anions migrate within the light-emitting layer, forming an electric double layer at the thin-film interface, thereby optimizing charge injection and transport. For example, Chinese invention patent application CN116940147A discloses a quantum dot electrochemical cell light-emitting device and its fabrication method, wherein the quantum dot electrochemical cell light-emitting layer includes a luminescent material, a hole transport material, and an ionic liquid. Currently, the best red quantum dot electrolyte light-emitting device only achieves a peak external quantum efficiency of 20.5% and a T95 lifetime of 6642 hours (1000 cd / m²). -2(See Adv. Mater. 2025, 37, 2417330) Its development is still lagging behind technologies such as QD-LED and organic light-emitting diode (OLED); and previous research has mostly focused on upright structures, making it difficult to avoid the problem of solvent erosion of hole transport layers; in addition, although green and blue light are the core elements for realizing full-color display, white light illumination and optical communication, the efficiency and stability of related quantum dot electrolyte light-emitting devices still need to be further improved.

[0004] However, existing quantum dot electrolyte light-emitting devices generally suffer from an imbalance between charge injection and transport, which limits the device's luminous efficiency and operating life. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and provide a quantum dot electrolyte light-emitting device and its preparation method, so as to solve the technical problem that the existing quantum dot electrolyte light-emitting devices generally have an imbalance between charge injection and transport, which leads to limited luminous efficiency and working life of the device.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A quantum dot electrolyte light-emitting device includes a substrate and a light-emitting stack structure disposed on the substrate; the light-emitting stack structure includes a cathode, an electron transport layer, a polymer blocking layer, a quantum dot electrolyte light-emitting layer, a hole transport layer, a hole injection layer and an anode stacked sequentially; the quantum dot electrolyte light-emitting layer includes a quantum dot light-emitting material and an ionic liquid.

[0008] In one possible implementation, the polymer barrier layer is made of polymethyl methacrylate (PMMA).

[0009] In one possible implementation, the thickness of the polymer barrier layer is 0.5-15 nm.

[0010] In one possible implementation, the ionic liquid is one or more of imidazole ionic liquids, pyridine ionic liquids, quaternary ammonium salt ionic liquids, and quaternary phosphonium salt ionic liquids.

[0011] In one possible implementation, the quantum dot electrolyte light-emitting layer is formed by forming a film from a quantum dot electrolyte solution.

[0012] In one possible implementation, the quantum dot luminescent material is a core-shell structured quantum dot, and the core-shell material composition of the core-shell structured quantum dot is one or more of CdSe / ZnS, CdZnS / ZnS, and CdZnSe / ZnSeS / ZnS.

[0013] In one possible implementation, the electron transport layer is made of one or more of TPBI, ZnO, ZnMgO, and SnO2; the hole transport layer is made of one or more of PEDOT:PSS, CBP, PVK, TFB, Poly-TPD, PF8CzCBP, mCP, BCBP, 26DCZPPy, TCTA, TAPC, NPB, TPD, m-MTDATA, and HAT-CN; the electrode near the substrate is a transparent electrode made of a transparent conductive oxide; the electrode away from the substrate is made of one or more of Ag, Al, Mo, ITO, and a stack of Cr and Au; the substrate is an alkali-free glass substrate or a flexible transparent substrate, so that the electroluminescent light is emitted through the substrate.

[0014] In one possible implementation, the cathode in the light-emitting stacked structure is disposed on the substrate, forming an inverted structure.

[0015] A method for fabricating a quantum dot electrolyte light-emitting device includes the following steps: depositing and patterning a cathode on a substrate; forming an electron transport layer on the cathode; forming a polymer barrier layer on the electron transport layer; forming a quantum dot electrolyte light-emitting layer on the polymer barrier layer; forming a hole transport layer on the quantum dot electrolyte light-emitting layer; forming a hole injection layer on the hole transport layer; and forming a patterned anode by evaporation deposition or sputtering on the hole injection layer in a vacuum environment.

[0016] In one possible implementation, the quantum dot electrolyte light-emitting layer is formed by any one of spin coating, blade coating, nanoimprinting, and printing; the electron transport layer, the polymer barrier layer, the hole transport layer, and the hole injection layer are each formed independently by any one of spin coating, blade coating, nanoimprinting, printing, and vapor deposition.

[0017] The present invention has the following advantages and effects compared with the prior art:

[0018] The quantum dot electrolyte luminescent layer of this invention comprises a quantum dot luminescent material and an ionic liquid. During device operation, the cations and anions dissociated from the ionic liquid migrate to the interfaces on both sides of the luminescent layer under the influence of an electric field, forming an electrical double layer. This lowers the carrier injection barrier and enhances and balances charge injection and transport. Simultaneously, a polymer barrier layer is disposed between the electron transport layer and the quantum dot electrolyte luminescent layer, blocking excess electrons injected from the electron transport layer side without affecting hole injection and transport. Thus, under the dual regulation of the ionic liquid and the polymer barrier layer, electrons and holes achieve balanced recombination, thereby solving the problem of charge injection and transport imbalance and significantly improving the device's luminous efficiency and lifespan. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of an inverted quantum dot electrolyte light-emitting device based on a PMMA barrier layer;

[0020] Figure 2 This is a schematic diagram illustrating the modulation of the device's operating energy band.

[0021] Figure 3 The frontier molecular orbital distribution diagram of the ionic liquid tetrabutylammonium bis(trifluoromethanesulfonyl)imide salt (TBA-TFSI);

[0022] Figure 4 This is a schematic diagram of the energy levels of each functional layer in the inverted quantum dot electrolyte light-emitting device of the present invention;

[0023] Figure 5 The external quantum efficiency-voltage curve of a quantum dot electrolyte light-emitting device;

[0024] Figure 6 This is a lifetime test curve of red, green, and blue quantum dot electrolyte light-emitting devices based on PMMA blocking layers at high initial brightness. Detailed Implementation

[0025] 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.

[0026] 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 is for the purpose of describing particular embodiments of the invention only and is not intended to limit the scope of the invention.

[0027] This application provides a quantum dot electrolyte light-emitting device, including a substrate and a light-emitting stacked structure disposed on the substrate; the light-emitting stacked structure includes a cathode, an electron transport layer, a polymer blocking layer, a quantum dot electrolyte light-emitting layer, a hole transport layer, a hole injection layer and an anode stacked sequentially; the quantum dot electrolyte light-emitting layer includes a quantum dot light-emitting material and an ionic liquid.

[0028] In some embodiments, the polymer barrier layer is made of polymethyl methacrylate (PMMA).

[0029] In some embodiments, the thickness of the polymer barrier layer is 0.5-15 nm.

[0030] In some embodiments, the ionic liquid is one or more of imidazole ionic liquids, pyridine ionic liquids, quaternary ammonium salt ionic liquids, and quaternary phosphonium salt ionic liquids.

[0031] In some embodiments, the quantum dot electrolyte light-emitting layer is formed by forming a film from a quantum dot electrolyte solution.

[0032] In some embodiments, the quantum dot luminescent material is a core-shell structured quantum dot, and the core-shell material composition of the core-shell structured quantum dot is one or more of CdSe / ZnS, CdZnS / ZnS, and CdZnSe / ZnSeS / ZnS.

[0033] In some embodiments, the electron transport layer is made of one or more of TPBI, ZnO, ZnMgO, and SnO2;

[0034] In some implementations, the hole transport layer material is one or more of PEDOT:PSS, CBP, PVK, TFB, Poly-TPD, PF8CzCBP, mCP, BCBP, 26DCZPPy, TCTA, TAPC, NPB, TPD, m-MTDATA, and HAT-CN.

[0035] In some embodiments, the electrode near the substrate is a transparent electrode made of a transparent conductive oxide, such as ITO.

[0036] In some embodiments, the material of the electrode away from the substrate is one or more of Ag, Al, Mo, ITO, and Cr-Au stacks;

[0037] In some embodiments, the substrate is an alkali-free glass substrate or a flexible transparent substrate, so that the electroluminescent light is emitted through the substrate.

[0038] In some embodiments, the cathode in the light-emitting stack structure is disposed on the substrate, forming an inverted structure.

[0039] This application also provides a method for fabricating the above-mentioned quantum dot electrolyte light-emitting device, comprising the following steps: depositing and patterning a cathode on a substrate; forming an electron transport layer on the cathode; forming a polymer barrier layer on the electron transport layer; forming a quantum dot electrolyte light-emitting layer on the polymer barrier layer; forming a hole transport layer on the quantum dot electrolyte light-emitting layer; forming a hole injection layer on the hole transport layer; and forming a patterned anode by evaporation deposition or sputtering on the hole injection layer in a vacuum environment.

[0040] In some embodiments, the quantum dot electrolyte light-emitting layer is formed by any one of spin coating, blade coating, nanoimprinting, and printing.

[0041] In some embodiments, the electron transport layer, polymer barrier layer, hole transport layer, and hole injection layer are each formed independently by any one of the following processes: spin coating, blade coating, nanoimprinting, printing, and vapor deposition.

[0042] Reference Figure 1 This embodiment provides a quantum dot electrolyte light-emitting device, including a substrate 1 and a light-emitting stacked structure disposed on the substrate 1; the light-emitting stacked structure includes a cathode 2, an electron transport layer 3, a polymer blocking layer 4, a quantum dot electrolyte light-emitting layer 5, a hole transport layer 6, a hole injection layer 7 and an anode 8 stacked sequentially; the quantum dot electrolyte light-emitting layer 5 includes a quantum dot light-emitting material and an ionic liquid.

[0043] Furthermore, the cathode 2 is disposed on the substrate 1, that is, the cathode 2 is closer to the substrate 1 than the anode 8, and the device constitutes an inverted structure.

[0044] Furthermore, substrate 1 is a transparent substrate and cathode 2 is a transparent electrode, so that the electroluminescent light is emitted sequentially through cathode 2 and substrate 1.

[0045] Furthermore, the polymer barrier layer 4 is a PMMA barrier layer, which is disposed between the electron transport layer 3 and the quantum dot electrolyte light-emitting layer 5; in some specific embodiments, the thickness of the polymer barrier layer 4 is 0.5-15 nm.

[0046] Specifically, the aforementioned quantum dot luminescent material can be quantum dots, meaning the quantum dot electrolyte luminescent layer comprises quantum dots and an ionic liquid. The ionic liquid dissociates into cations and anions within the quantum dot electrolyte luminescent layer. The blended system of the quantum dot luminescent material and the ionic liquid is the quantum dot electrolyte (QE), and the quantum dot electrolyte luminescent layer is formed by film formation from this blended system. (Refer to...) Figure 2 and Figure 1 When the device is operating, cations migrate towards the interface on the electron transport layer side under the influence of the electric field, while anions migrate towards the interface on the hole transport layer side, forming an electric double layer at the interface. This lowers the carrier injection barrier, enhances charge injection and transport, and thus improves the imbalance between charge injection and transport. (Refer to...) Figure 3 The lowest unoccupied molecular orbitals (LUMOs) and highest occupied molecular orbitals (HOMOs) of the ionic liquid TBA-TFSI are spatially separated and localized on different ionic components of the ionic liquid. Based on this, the ionic liquid can dissociate under the influence of an electric field, causing cations and anions to migrate to the interfaces on both sides of the light-emitting layer, thereby forming the aforementioned electric double layer. The cathode 2 is used to inject electrons into the light-emitting stacked structure, and the electron transport layer 3 is used to transport electrons from the cathode 2 to the quantum dot electrolyte light-emitting layer 5.

[0047] Specifically, the PMMA blocking layer 4 is disposed between the electron transport layer 3 and the quantum dot electrolyte luminescent layer 5, rather than being incorporated into the luminescent layer itself. For example... Figure 2 As shown, Figure 2The diagrams, from left to right, show the energy band structure before and after the introduction of the ionic liquid and polymer barrier layer, after ion doping with the ionic liquid, and after the addition of a PMMA barrier layer. As can be seen, in the device with only ion doping, excess electron leakage still exists, while the electron leakage is effectively suppressed after the addition of the PMMA barrier layer. (Refer to...) Figure 4 In this embodiment, the work function of the transparent cathode 2 (ITO) is approximately -4.9 eV, the conduction band bottom and valence band top of the electron transport layer 3 (ZnMgO) are approximately -3.4 eV and -7.1 eV, respectively, the LUMO and HOMO of the quantum dot electrolyte luminescent layer are approximately -4.2 eV and -6.2 eV, respectively, the LUMO and HOMO of the hole transport layer 6 (CBP) are approximately -2.9 eV and -6.0 eV, respectively, the work function of the hole injection layer 7 (MoO3) is approximately -5.5 eV, and the work function of the anode 8 (Ag) is approximately -4.3 eV. PMMA is a wide bandgap insulating polymer with a HOMO of approximately -8.6 eV, a LUMO of approximately -0.5 to -1.0 eV, and a bandgap of approximately 7.6 to 8.1 eV. Its LUMO is approximately 2.4 to 2.9 eV higher than the conduction band bottom of the electron transport layer 3, thus forming a significant electron injection barrier between the electron transport layer 3 and the quantum dot electrolyte luminescent layer 5. The thickness of the PMMA barrier layer 4 is controlled at 0.5-15 nm (approximately 4 nm in this embodiment). Electrons tunnel through this barrier in a restricted manner, reducing the electron injection rate from the electron transport layer 3 to a level matching that of holes, thereby suppressing the injection and leakage of excess electrons. Holes are injected from the HOMO (approximately -6.0 eV) of the hole transport layer 6 into the HOMO (approximately -6.2 eV) of the quantum dot electrolyte luminescent layer. The injection path does not pass through the PMMA barrier layer 4, so hole injection and transport are unaffected. Existing schemes that incorporate PMMA into the luminescent layer in an upright structure can suppress electron leakage to some extent, but the insulating properties of PMMA will simultaneously suppress hole injection and transport. In this embodiment, the PMMA barrier layer is independently placed between the electron transport layer and the luminescent layer, which only blocks excess electrons injected from the electron transport layer 3 side without affecting hole injection and transport. Thus, electron leakage is effectively suppressed without sacrificing hole injection and transport, and a balanced recombination of electrons and holes is achieved under the dual regulation of the ionic liquid and the PMMA barrier layer.

[0048] Furthermore, the inverted structure allows the upper functional layers, such as the hole transport layer 6 and the hole injection layer 7, to be formed after the light-emitting layer. This enables the use of dry processes such as thermal evaporation, avoiding the erosion of the hole transport layer by solvents in solution-based preparation. At the same time, the inverted structure is compatible with mature n-channel amorphous silicon thin-film transistor (TFT) driving circuits, which is beneficial for the low-cost manufacturing of large-size active matrix displays.

[0049] Specifically, in this embodiment, the transparent substrate 1 is an alkali-free glass substrate, the transparent cathode 2 is an ITO electrode, the electron transport layer 3 is made of ZnMgO, the quantum dots are cadmium-based core-shell quantum dots with oleic acid as the surface ligand, the ionic liquid is tetrabutylammonium bis(trifluoromethanesulfonyl)imide (TBA-TFSI), the hole transport layer 6 is made of CBP, and the anode 8 is an Ag electrode. The hole injection layer 7 is made of materials such as MoO3, WO3, and V2O5, and is deposited using a vacuum evaporation process with a thickness of 2-20 nm. It is positioned between the hole transport layer 6 and the anode 8 to reduce the hole injection barrier.

[0050] In some embodiments, the transparent substrate 1 may also be a flexible transparent substrate, such as a polyimide (PI) substrate, which can withstand temperatures up to 350°C, meeting the process requirements for annealing the electron transport layer 3 at 70-200°C, so that the electroluminescent light is emitted through the substrate; in some embodiments, the anode 8 may also be made of materials such as Al, Mo, ITO, or a stack of Cr and Au; in some embodiments, the electron transport layer 3 may also be made of materials such as TPBI, ZnO, SnO2; in some embodiments, the hole transport layer 6 may also be made of materials such as PEDOT:PSS, PVK, TFB, Poly-TPD, PF8CzCBP, mCP, BCBP, 26DCZPPy, TCTA, TAPC, NPB, TPD, m-MTDATA, HAT-CN, etc., wherein PEDOT:PSS and HAT... -CN can also be used as a material for the hole injection layer; in some embodiments, the quantum dots can be core-shell structured quantum dot luminescent materials such as CdSe / ZnS, CdZnS / ZnS, CdZnSe / ZnSeS / ZnS, etc. In the above composition formula, the parts separated by " / " represent the core layer and each shell layer material from left to right. For example, CdSe / ZnS represents a quantum dot with CdSe as the core and ZnS as the shell, and CdZnSe / ZnSeS / ZnS represents a quantum dot with CdZnSe as the core, ZnSeS as the inner shell and ZnS as the outer shell; the ionic liquid can also be imidazole (such as [BMIM][PF6]), pyridine (such as [BPy][BF4]), quaternary ammonium salt (such as [N444-4]Cl) or quaternary phosphonium salt (such as [P666-14][NTf2]) ionic liquid. Those skilled in the art may also select other substrate, electrode, electron transport layer, polymer barrier layer, quantum dot, ionic liquid, hole transport layer and hole injection layer materials other than those mentioned above according to actual needs, and the embodiments of this application do not limit this.

[0051] In one embodiment, the cathode in the above preparation method can be an ITO transparent cathode, the electron transport layer can be a ZnMgO layer, the polymer barrier layer can be a PMMA barrier layer, the hole transport layer can be a CBP layer, the hole injection layer can be a MoO3 layer, and the anode can be an Ag anode. The preparation method of the above quantum dot electrolyte light-emitting device includes the preparation of the quantum dot electrolyte solution and the layer-by-layer fabrication of the device, which will be described below through Examples 1 and 2.

[0052] Example 1: Preparation of quantum dot electrolyte solution

[0053] S1: Wash and dry the 2.0 mL sample vial; S2: Add 50 mg / mL quantum dot solution with chlorobenzene or toluene as solvent to the clean glass vial; S3: Add an appropriate amount of chlorobenzene or toluene solvent to the glass vial to dilute the quantum dot solution to 10 mg / mL; S4: Add the ionic liquid TBA-TFSI and heat and stir at 60℃ for 10 minutes to obtain the quantum dot electrolyte solution. The mass percentage of the ionic liquid in the red quantum dot electrolyte solution (the sum of the mass of quantum dots and ionic liquid) is 4.0 wt.%, the green quantum dot solution is 7.5 wt.%, and the blue quantum dot electrolyte solution is 3.0 wt.%.

[0054] Example 2: Fabrication of quantum dot electrolyte light-emitting devices

[0055] S1: Clean and dry the glass substrate; S2: Deposit and pattern an ITO transparent cathode on the glass substrate; S3: Spin-coat or inkjet print an electron transport layer (ZnMgO) on the cathode, with a thickness of 10-60 nm, annealing temperature of 70-200℃, and annealing time of 5-60 minutes; S4: Spin-coat or deposit a PMMA barrier layer on the electron transport layer, with a PMMA solution concentration of 1-15 mg / mL and a thickness range of 0.5-15 nm, the optimal thickness being 4 nm (too thick and the device becomes essentially insulated, too thin and the barrier effect is poor), spin-coating speed of 500-5000 rpm, and time of 1-60 s; S5: Spin-coat the quantum dot electrolyte solution prepared in Example 1 on the PMMA barrier layer to form a quantum dot electrolyte luminescent layer, spin-coating speed of 500-5000 rpm, and time of 1-60 s. S6: Depositing a hole transport layer (CBP) on the quantum dot electrolyte luminescent layer. During vacuum evaporation, the deposition rate is 0.001 nm / s-1 nm / s, and the vacuum level is less than 1×10⁻⁶. -4 Pa, then a hole injection layer is deposited on it. During vacuum evaporation, the evaporation rate is 0.001 nm / s-0.2 nm / s, and the vacuum degree is less than 1×10. -4Pa; S7: In a vacuum environment, patterned Ag anodes are deposited or sputtered on the hole injection layer by evaporation deposition or sputtering. During vacuum evaporation, the deposition rate is 0.01 nm / s-2 nm / s, and the vacuum degree is less than 1×10⁻⁶. -3 Pa, complete the device fabrication.

[0056] Furthermore, the quantum dot electrolyte light-emitting layer can also be formed by processes such as blade coating, nanoimprinting, or printing; the electron transport layer, PMMA blocking layer, hole transport layer, and hole injection layer can also be formed by processes such as blade coating, nanoimprinting, printing, or evaporation. Those skilled in the art can also select other film-forming processes besides those mentioned above according to actual needs, and the embodiments of this application do not limit this.

[0057] The devices prepared by the above method were subjected to performance testing: such as Figure 5 As shown, Figure 5 In the figure, w / o PMMA represents no PMMA and wPMMA represents with PMMA. The figures show the comparison curves of the red light device with and without the PMMA blocking layer, the curves of the green and blue light devices based on the PMMA blocking layer, the curve of the green control device without the PMMA blocking layer, and the curve of the blue control device without the PMMA blocking layer. As can be seen from the figures, the external quantum efficiencies of the red, green, and blue quantum dot electrolyte light-emitting devices reach 24.2%, 20.3%, and 13.5%, respectively, all higher than the corresponding control devices without the PMMA blocking layer. Specifically, the external quantum efficiencies of the red, green, and blue control devices are 20%, 13.7%, and 8.0%, respectively. Figure 6 The lifetime test curves of quantum dot electrolyte light-emitting devices at high initial brightness are shown. The insets of each graph represent the fitting relationship between the T95 lifetime and the initial brightness of the device. The red, green, and blue devices have initial brightness levels of 33000 cd / m², respectively. -2 26600 cd m -2 and 3300 cd m -2 The measured T95 lifetimes were 21.9 hours, 30.16 hours, and 25.3 hours, respectively. Based on the acceleration relationship where the product of the initial brightness (power of n) and the T95 lifetime is constant, the acceleration factors n for red, green, and blue devices were obtained by fitting the measured lifetimes at different initial brightness levels: 1.83, 1.88, and 1.90, respectively. These factors can be extrapolated to 1000 cd / m². -2 The initial brightness, T of red, green, and blue devices 95 The lifetimes are 13,100 hours, 14,400 hours and 244.5 hours respectively, with the blue light device representing the state-of-the-art performance of bottom-emitting electroluminescent devices based on quantum dots.

[0058] The embodiments of this application can achieve the following beneficial effects: First, the quantum dot electrolyte light-emitting layer includes quantum dot light-emitting material and ionic liquid. When the device is working, the anions and cations dissociated by the ionic liquid migrate to the interfaces on both sides of the light-emitting layer under the action of the electric field to form an electric double layer, which reduces the carrier injection barrier, improves charge injection and transport, and improves the imbalance between charge injection and transport. Second, the polymer barrier layer is disposed between the electron transport layer and the quantum dot electrolyte light-emitting layer, rather than being incorporated into the light-emitting layer. It only blocks excess electrons injected from the electron transport layer side and does not affect hole injection and transport, thereby effectively suppressing electron leakage without sacrificing hole injection and transport. Third, the inverted structure in which the cathode, electron transport layer, polymer barrier layer, light-emitting layer and anode are stacked sequentially from bottom to top allows the upper functional layers such as the hole transport layer to be formed after the light-emitting layer by processes such as thermal evaporation, avoiding the erosion of the hole transport layer by solvents and being compatible with the n-channel amorphous silicon TFT driving circuit. Thus, under the dual regulation of ionic liquid and polymer barrier layer, electrons and holes achieve balanced recombination. Experiments show that the external quantum efficiencies of the red, green, and blue quantum dot electrolyte light-emitting devices of this invention reach 24.2%, 20.3%, and 13.5%, respectively, all higher than the corresponding control devices without polymer barrier layer. Extrapolation of the lifetime-luminosity relationship to 1000 cd / m² further demonstrates this. -2 The initial brightness, T of red, green, and blue devices 95 The lifetimes are 13,100 hours, 14,400 hours and 244.5 hours respectively, with the blue light device representing the state-of-the-art performance of bottom-emitting electroluminescent devices based on quantum dots.

[0059] The embodiments described in this invention are for the purpose of more clearly illustrating the technical solutions of this invention, and do not constitute a limitation on the technical solutions of this invention. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions of this invention are also applicable to similar technical problems.

[0060] The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but this does not limit the scope of the invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and spirit of the present invention should be within the scope of the present invention.

Claims

1. A quantum dot electrolyte light-emitting device, characterized in that, The invention includes a substrate and a light-emitting stacked structure disposed on the substrate; the light-emitting stacked structure includes a cathode, an electron transport layer, a polymer blocking layer, a quantum dot electrolyte light-emitting layer, a hole transport layer, a hole injection layer, and an anode stacked sequentially; the quantum dot electrolyte light-emitting layer includes a quantum dot light-emitting material and an ionic liquid.

2. The quantum dot electrolyte light-emitting device according to claim 1, characterized in that, The polymer barrier layer is made of polymethyl methacrylate (PMMA).

3. The quantum dot electrolyte light-emitting device according to claim 2, characterized in that, The thickness of the polymer barrier layer is 0.5-15 nm.

4. The quantum dot electrolyte light-emitting device according to claim 1, characterized in that, The ionic liquid is one or more of the following: imidazole ionic liquid, pyridine ionic liquid, quaternary ammonium salt ionic liquid, and quaternary phosphonium salt ionic liquid.

5. The quantum dot electrolyte light-emitting device according to claim 1, characterized in that, The quantum dot electrolyte luminescent layer is formed by forming a film from a quantum dot electrolyte solution.

6. The quantum dot electrolyte light-emitting device according to claim 1, characterized in that, The quantum dot luminescent material is a core-shell structured quantum dot, and the core-shell material composition of the core-shell structured quantum dot is one or more of CdSe / ZnS, CdZnS / ZnS, and CdZnSe / ZnSeS / ZnS.

7. The quantum dot electrolyte light-emitting device according to claim 1, characterized in that, The electron transport layer is made of one or more of TPBI, ZnO, ZnMgO, and SnO2; the hole transport layer is made of one or more of PEDOT:PSS, CBP, PVK, TFB, Poly-TPD, PF8CzCBP, mCP, BCBP, 26DCZPPy, TCTA, TAPC, NPB, TPD, m-MTDATA, and HAT-CN; the electrode near the substrate is a transparent electrode made of a transparent conductive oxide; the electrode away from the substrate is made of one or more of Ag, Al, Mo, ITO, and a stack of Cr and Au; the substrate is an alkali-free glass substrate or a flexible transparent substrate, so that the electroluminescent light is emitted through the substrate.

8. The quantum dot electrolyte light-emitting device according to claim 1, characterized in that, The cathode in the light-emitting stacked structure is disposed on the substrate, forming an inverted structure.

9. A method for fabricating a quantum dot electrolyte light-emitting device, used to fabricate the quantum dot electrolyte light-emitting device according to any one of claims 1 to 8, characterized in that, The method includes the following steps: depositing and patterning a cathode on a substrate; forming an electron transport layer on the cathode; forming a polymer barrier layer on the electron transport layer; forming a quantum dot electrolyte light-emitting layer on the polymer barrier layer; forming a hole transport layer on the quantum dot electrolyte light-emitting layer; forming a hole injection layer on the hole transport layer; and forming a patterned anode by evaporation deposition or sputtering on the hole injection layer in a vacuum environment.

10. The preparation method according to claim 9, characterized in that, The quantum dot electrolyte light-emitting layer is formed by any one of spin coating, blade coating, nanoimprinting, and printing; the electron transport layer, the polymer barrier layer, the hole transport layer, and the hole injection layer are each formed independently by any one of spin coating, blade coating, nanoimprinting, printing, and vapor deposition.

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