Laminated quantum dot light-emitting diode based on photo-crosslinking and full-solution preparation method thereof
The cross-linked electron transport layer is prepared in the stacked quantum dot light-emitting diode through photo-cross-linking technology, which solves the problem of mutual dissolution between layers and improves the electroluminescence efficiency of the device and the quality of the film layer.
Patent Information
- Application Number
- CN202411437191.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-15
- Publication Date
- 2025-01-21
AI Technical Summary
In the prior art, stacked quantum dot light emitting diodes have interlayer intersoluble phenomena during the whole solution preparation process, resulting in deterioration of the functional layer interface and affecting device performance.
The optical cross -linking technology is adopted to form an ink by mixing the methadosterial agent polymers and the electronic transmission layer material, which is prepared after the rotary coating and ultraviolet light processing.
It improves the solubility resistance of the electron transport layer, reduces the corrosion of the film layer, and improves the density and flatness of the film layer, thus significantly improving the electroluminescence efficiency of the device.
Smart Images
Figure CN119342982A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of display technology, and in particular relates to a laminated quantum dot light emitting diode based on photo-crosslinking and a full solution preparation method thereof. Background Art
[0002] In recent years, colloidal quantum dot light-emitting diodes (QLEDs) have attracted widespread attention as the next generation of display technology. Compared with traditional organic light-emitting diodes (OLEDs) and liquid crystal displays (LCDs), QLEDs have shown significant advantages in the field of display technology. These advantages include high color purity, wide color gamut, tunable emission wavelength, and great potential based on low-cost solution preparation methods.
[0003] Although QLEDs have performed well in many aspects, their low efficiency and insufficient stability remain important factors that restrict their widespread application. In order to further improve the performance of QLEDs, people have begun to explore improvement methods, among which the use of stacked structures is considered to be an effective solution. However, although stacked quantum dot light-emitting diodes have shown great potential in performance, there are still relatively few related studies and reports, especially stacked quantum dot light-emitting diodes prepared by the all-solution method. The preparation of stacked quantum dot light-emitting diodes faces many challenges, the most critical of which is the solvent orthogonality problem between functional layers. Since stacked quantum dot light-emitting diodes are composed of multiple functional layers, the solution treatment of each layer will affect the morphology and function of other layers, especially the problem of solvent orthogonality between adjacent layers. When solvent erosion occurs, it will cause the interface of the functional layer to deteriorate, thereby affecting the overall performance of the device. In addition, due to the relatively complex structure of the stacked device and the penetration of solvent when depositing the top functional layer or the light-emitting layer due to the fact that the film layer is not dense enough, the quality and uniformity of each layer may gradually decrease during the preparation process, especially after multiple solvent treatments, interlayer dissolution is prone to occur. This phenomenon not only damages the morphology of the film, but can also lead to mismatched electrical properties between functional layers, further affecting the overall performance of the device. The film layers made by thermal evaporation are also susceptible to damage during subsequent solution processing, resulting in poor device performance. Summary of the invention
[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a photo-crosslinked laminated quantum dot light-emitting diode and a full solution preparation method thereof, wherein a crosslinkable polymer and an electron transport layer are blended to prepare ink, and the ink is subjected to spin coating and exposure processes to achieve the preparation of a crosslinked electron transport layer. The device film layer prepared using this method has higher density, more uniform thickness and lower surface roughness, and has good solubility resistance. The present invention can effectively avoid the phenomenon of interlayer dissolution in the process of preparing laminated quantum dot light-emitting diodes by the full solution method, thereby significantly improving the electroluminescent efficiency of the device and broadening the selection range of solvents for the light-emitting layer and the functional layer.
[0005] To achieve the above-mentioned purpose, the technical solution of the present invention is: a stacked quantum dot light-emitting diode based on photo-crosslinking, comprising an anode, a first hole injection layer, a first hole transport layer, a first quantum dot light-emitting layer, a cross-linked electron transport layer, a second hole injection layer, a second hole transport layer, a second quantum dot light-emitting layer, an electron transport layer, and a metal cathode arranged in sequence from bottom to top; wherein the cross-linked electron transport layer and the second hole injection layer together constitute a connecting layer; the cross-linked electron transport layer is obtained by blending a cross-linkable polymer containing a photosensitizer with an electron transport layer material to form an ink, and then subjecting the ink to spin coating and ultraviolet light treatment.
[0006] The present invention also provides a full solution preparation method of a stacked quantum dot light-emitting diode based on photo-crosslinking, comprising: S1, depositing an anode, a first hole injection layer, a first hole transport layer, and a first quantum dot light-emitting layer on a substrate in sequence; S2, uniformly blending a cross-linkable polymer containing a photosensitizer and an electron transport layer material in a predetermined ratio to obtain ink; S3, using a coating machine to spin-coat the ink on the first quantum dot light-emitting layer to form a film; S4, cross-linking the cross-linkable polymer by ultraviolet light to obtain a cross-linked electron transport layer; S5. Depositing a second hole injection layer, a second hole transport layer, a second quantum dot light-emitting layer, an electron transport layer, and a metal cathode in sequence on the cross-linked electron transport layer to obtain a stacked quantum dot light-emitting diode based on photo-cross-linking.
[0007] In one embodiment of the present invention, the cross-linkable polymer is one of a series of polymers including polyvinyl butyral (PVB).
[0008] In one embodiment of the present invention, the photosensitizer is one of benzoin dimethyl ether, bis(dibenzophenone) and benzophenone.
[0009] In one embodiment of the present invention, the electron transport layer material constituting the cross-linked electron transport layer is an n-type metal oxide nanoparticle film; the n-type metal oxide nanoparticles are ZnMgO, ZnO nanoparticles, ZnO nanoparticles doped with metal cations, and a mixture of ZnO nanoparticles and polymers.
[0010] In one embodiment of the present invention, the material of the hole injection layer is one of a polymer poly 3,4-ethylenedioxythiophene (PEDOT:PSS), molybdenum oxide, nickel oxide, and cuprous thiocyanate.
[0011] In one embodiment of the present invention, the material of the hole transport layer is one or a mixture of polymer 1,2,4,5-tetrakis(trifluoromethyl)benzene (TFB), polytriphenylamine (Poly:TPD), and polyvinylcarbazole (PVK).
[0012] In one embodiment of the present invention, the electron transport layer is an n-type metal oxide nanoparticle film; the n-type metal oxide nanoparticles are ZnMgO, ZnO nanoparticles, ZnO nanoparticles doped with metal cations, or a mixture of ZnO nanoparticles and polymers.
[0013] In one embodiment of the present invention, the material of the quantum dots in the first and second quantum dot light-emitting layers is one of CdSe / ZnS, InP, and halogen perovskite.
[0014] In one embodiment of the present invention, the material of the metal cathode is silver or aluminum.
[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) After the ink is subjected to spin coating and cross-linking processes, the solubility resistance of the electron transport layer is improved, and the erosion of the film layer due to non-orthogonal solvents between adjacent functional layers is reduced; (2) The cross-linked electron transport layer film has a higher density and lower surface roughness, which helps to improve the smoothness of subsequent film formation; (3) This method achieves a higher charge generation efficiency by cross-linking the connecting layer of the stacked quantum dot light-emitting device, thereby improving the electroluminescence efficiency of the device. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 is a schematic diagram of the device structure of the present invention; Figure 2 It is a schematic diagram of the preparation process of a cross-linked electron transport layer according to Example 1 of the present invention. DETAILED DESCRIPTION
[0017] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.
[0018] The present invention provides a stacked quantum dot light-emitting diode based on photo-crosslinking, comprising an anode, a first hole injection layer, a first hole transport layer, a first quantum dot light-emitting layer, a crosslinked electron transport layer, a second hole injection layer, a second hole transport layer, a second quantum dot light-emitting layer, an electron transport layer, and a metal cathode, which are arranged in sequence from bottom to top; wherein the crosslinked electron transport layer and the second hole injection layer together constitute a connecting layer; the crosslinked electron transport layer is obtained by blending a crosslinkable polymer containing a photosensitizer with an electron transport layer material to form ink, and then subjecting the ink to spin coating and ultraviolet light treatment.
[0019] The present invention also provides a full solution preparation method of a stacked quantum dot light-emitting diode based on photo-crosslinking, comprising: S1, depositing an anode, a first hole injection layer, a first hole transport layer, and a first quantum dot light-emitting layer on a substrate in sequence; S2, uniformly blending a cross-linkable polymer containing a photosensitizer and an electron transport layer material in a predetermined ratio to obtain ink; S3, using a coating machine to spin-coat the ink on the first quantum dot light-emitting layer to form a film; S4, cross-linking the cross-linkable polymer by ultraviolet light to obtain a cross-linked electron transport layer; S5. Depositing a second hole injection layer, a second hole transport layer, a second quantum dot light-emitting layer, an electron transport layer, and a metal cathode in sequence on the cross-linked electron transport layer to obtain a stacked quantum dot light-emitting diode based on photo-cross-linking.
[0020] The following are specific implementation examples of the present invention.
[0021] Example: In this embodiment, reference Figure 1 , specifically comprising the following steps: 1) The ITO conductive film prepared by magnetron sputtering is used as the anode substrate.
[0022] 2) The anode substrate is sequentially placed in glass cleaning agent, deionized water, acetone, and ethanol for ultrasonic treatment, and the duration of each ultrasonic treatment is 10 minutes.
[0023] 3) PEDOT:PSS was prepared as the first hole injection layer by spin coating with an annealing temperature of 120 °C and a thickness of about 30 nm.
[0024] 4) TFB was prepared as the first hole transport layer by spin coating with an annealing temperature of 120 °C and a thickness of about 40 nm.
[0025] 5) Prepare quantum dots as the first quantum dot light-emitting layer by spin coating, with an annealing temperature of 80°C and a thickness of about 30 nm.
[0026] 6) Spin-coat the first quantum dot light-emitting layer with ink as a cross-linked electron transport layer with a thickness of about 40nm. Figure 2 As shown, the process specifically includes the following steps: pre-mixing a cross-linkable polymer PVB containing a photosensitizer and zinc oxide nanocrystal particles in a certain proportion, spin coating them into a film using a coating machine at a speed of 3000r for 40s, and cross-linking the cross-linkable polymer by exposure to light to construct a cross-linked electron transport layer.
[0027] 7) PEDOT:PSS was prepared as the second hole injection layer by spin coating with an annealing temperature of 80°C and a thickness of about 30 nm.
[0028] 8) TFB was prepared as the second hole transport layer by spin coating with an annealing temperature of 80 °C and a thickness of about 40 nm.
[0029] 5) Prepare quantum dots as the second quantum dot light-emitting layer by spin coating, with an annealing temperature of 80°C and a thickness of about 30 nm.
[0030] 6) ZnO was prepared as the electron transport layer by spin coating with an annealing temperature of 80 °C and a thickness of about 50 nm.
[0031] 7) Ag electrode was deposited by vacuum evaporation method with a thickness of 100 nm.
[0032] The above are preferred embodiments of the present invention. Any changes made according to the technical solution of the present invention, as long as the resulting functions do not exceed the scope of the technical solution of the present invention, belong to the protection scope of the present invention.
Claims
1. A stacked quantum dot light-emitting diode based on photo-crosslinking, characterized in that: It includes an anode, a first hole injection layer, a first hole transport layer, a first quantum dot light-emitting layer, a cross-linked electron transport layer, a second hole injection layer, a second hole transport layer, a second quantum dot light-emitting layer, an electron transport layer, and a metal cathode, which are arranged in sequence from bottom to top; wherein the cross-linked electron transport layer and the second hole injection layer together constitute a connecting layer; the cross-linked electron transport layer is obtained by blending a cross-linkable polymer containing a photosensitizer with an electron transport layer material to form ink, and then subjecting the ink to spin coating and ultraviolet light treatment.
2. A full solution preparation method for a stacked quantum dot light-emitting diode based on photo-crosslinking as claimed in claim 1, characterized in that: include: S1, depositing an anode, a first hole injection layer, a first hole transport layer, and a first quantum dot light-emitting layer on a substrate in sequence; S2, uniformly blending a cross-linkable polymer containing a photosensitizer and an electron transport layer material in a predetermined ratio to obtain ink; S3, using a coating machine to spin-coat the ink on the first quantum dot light-emitting layer to form a film; S4, cross-linking the cross-linkable polymer by ultraviolet light to obtain a cross-linked electron transport layer; S5. Depositing a second hole injection layer, a second hole transport layer, a second quantum dot light-emitting layer, an electron transport layer, and a metal cathode in sequence on the cross-linked electron transport layer to obtain a stacked quantum dot light-emitting diode based on photo-cross-linking.
3. The full solution preparation method of a stacked quantum dot light-emitting diode based on photo-crosslinking according to claim 2, characterized in that: The cross-linkable polymer is one of a series of polymers including polyvinyl butyral (PVB).
4. The method for preparing a full solution of a stacked quantum dot light-emitting diode based on photo-crosslinking according to claim 2, characterized in that: The photosensitizer is one of benzoin dimethyl ether, bis(dibenzophenone) and benzophenone.
5. The method for preparing a full solution of a stacked quantum dot light-emitting diode based on photo-crosslinking according to claim 2, characterized in that: The electron transport layer material constituting the cross-linked electron transport layer is an n-type metal oxide nanoparticle film; the n-type metal oxide nanoparticles are ZnMgO, ZnO nanoparticles, ZnO nanoparticles doped with metal cations, and a mixture of ZnO nanoparticles and polymers.
6. The method for preparing a full solution of a stacked quantum dot light-emitting diode based on photo-crosslinking according to claim 2, characterized in that: The material of the hole injection layer is one of a polymer poly 3,4-ethylenedioxythiophene (PEDOT:PSS), molybdenum oxide, nickel oxide, and cuprous thiocyanate.
7. The method for preparing a full solution of a stacked quantum dot light-emitting diode based on photo-crosslinking according to claim 2, characterized in that: The material of the hole transport layer is one or a mixture of polymer 1,2,4,5-tetrakis(trifluoromethyl)benzene (TFB), polytriphenylamine (Poly:TPD), and polyvinylcarbazole (PVK).
8. The method for preparing a full solution of a stacked quantum dot light-emitting diode based on photo-crosslinking according to claim 2, characterized in that: The electron transport layer is an n-type metal oxide nanoparticle film; the n-type metal oxide nanoparticles are ZnMgO, ZnO nanoparticles, ZnO nanoparticles doped with metal cations, and a mixture of ZnO nanoparticles and polymers.
9. The method for preparing a full solution of a stacked quantum dot light-emitting diode based on photo-crosslinking according to claim 2, characterized in that: The material of the quantum dots in the first and second quantum dot light-emitting layers is one of CdSe / ZnS, InP, and halogen perovskite.
10. The full solution preparation method of a stacked quantum dot light-emitting diode based on photo-crosslinking according to claim 2, characterized in that: The material of the metal cathode is silver or aluminum.