Preparation method of high-performance ultrahigh-resolution circularly polarized light emitting diode

Abstract

The invention relates to a preparation method of a high-performance ultrahigh-resolution circularly polarized light-emitting diode, and relates to the technical field of quantum dot light-emitting diodes (QLEDs). Firstly, high-resolution quantum dot pixel points are prepared on a target substrate through a transfer printing process, and a uniform and high-density pixel point array is formed by accurately controlling arrangement and distribution of the quantum dots. And then, spin-coating a layer of two-dimensional chiral perovskite thin film on the pixel points of the quantum dots, and realizing high-efficiency circularly polarized light emission by utilizing a chiral induced spin selectivity (CISS) effect. According to the method, by optimizing the uniformity of the quantum dot film and the thickness of the chiral perovskite, the circular polarization luminous efficiency is remarkably improved, meanwhile, the high resolution and high brightness characteristics of the quantum dot light-emitting diode are kept, the method can stably work at the room temperature without an external magnetic field, and good electrical performance and optical stability are achieved.

Description

Technical Field

[0001] The present invention relates to the field of quantum dot light-emitting diode (QLED) technology, particularly to a method for preparing high-performance, ultra-high-resolution circularly polarized LEDs. More specifically, it relates to a method for preparing ultra-high-resolution circularly polarized LEDs using the Langmuir-Blodgett (LB) process and chiral perovskite thin films. This technology has applications in display technology, optical communications, quantum computing, and 3D displays. Background Art

[0002] With the continuous development of display technology, the demand for high-resolution, high-performance display devices is growing. QLEDs, with their excellent performance such as high color purity, high brightness, and narrow emission spectrum, have become a strong candidate for next-generation display technology. Although relevant research has been conducted on high-resolution QLED displays, achieving ultra-high-resolution circularly polarized light emission in QLEDs remains a challenge. Circularly polarized light emission technology has broad application prospects in optical communications, quantum computing, and 3D displays, but existing methods still have shortcomings in circularly polarized light emission efficiency and resolution.

[0003] Two-dimensional chiral perovskite materials, due to their unique chirality-induced spin selectivity (CISS) effect, enable efficient spin-polarized carrier injection. By combining chiral perovskites with quantum dots, they hold promise for realizing high-resolution circularly polarized light-emitting diodes. However, achieving uniform chiral perovskite films on ultra-high-resolution quantum dot pixels and optimizing their circularly polarized luminescence performance remain pressing technical challenges. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention combines the ultra-high-resolution quantum dot pixel preparation technology with the CISS effect of chiral perovskite, and proposes a high-performance ultra-high-resolution circularly polarized light-emitting diode preparation method. The specific operation is to first use the Langmuir-Blodgett film-forming process to prepare high-resolution quantum dot pixels. The LB process can accurately control the arrangement and distribution of quantum dots to form a high-quality pixelated quantum dot film, which provides a basis for achieving ultra-high-resolution display. Furthermore, a layer of chiral perovskite film is spin-coated on the pixel points. With the help of the special optical properties of chiral perovskite and the chirality-induced spin-selective CISS effect, the device can achieve circularly polarized light emission, which expands the application range of QLED in the display and optical fields, and has potential value in 3D display, polarization imaging and other aspects.

[0005] The specific technical solutions are as follows:

[0006] A method for preparing high-performance, ultra-high-resolution circularly polarized light-emitting diodes, comprising sequentially depositing a hole injection layer, a hole transport layer, a charge blocking layer and a quantum dot pixel thin film layer combination layer, an electron transport layer, and a metal cathode on an ITO layer of a transparent conductive substrate;

[0007] The charge blocking layer and the quantum dot pixel thin film layer combination layer is prepared by a transfer-combined spin coating method, specifically comprising the following steps:

[0008] Step 1: First, prepare a polydimethylsiloxane (PDMS) stamp with a concave structure on the surface;

[0009] Step 2: forming a single-layer charge blocking layer LB film on an LB film drawing machine;

[0010] Step 3: Use a PDMS stamp with a concave structure on the surface to remove the charge blocking layer LB film so that the charge blocking layer is picked up on the top of the concave structure;

[0011] Step 4: Laminating the above-mentioned stamp onto the hole transport layer, heating the PDMS stamp, and peeling off the stamp to form a honeycomb-shaped charge blocking layer on the hole transport layer;

[0012] Step 5: Spin-coating the quantum dot solution onto the honeycomb-shaped charge blocking layer so that the quantum dots are evenly filled in the honeycomb to achieve quantum dot pixelation;

[0013] Step 6: Annealing the pixelated quantum dots on the hole transport layer.

[0014] The hole injection layer material is one of thiocyanate ketone (CuSCN), polystyrene sulfonate (PEDOT:PSS), molybdenum oxide (MoO3), tungsten oxide (WO3), and vanadium pentoxide (V2O5);

[0015] The hole transport layer material is one or a mixture of poly[bis(4-phenyl)(4-butylphenyl)amine] (Poly-TPD), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] (TFB), and polyvinylcarbazole (PVK);

[0016] The quantum dot material is one of CdSe, InP, and perovskite;

[0017] The charge blocking layer material can be an organic material, such as polyethylene, polyvinyl chloride, etc., or an inorganic material, such as nano-silicon dioxide, sodium yttrium fluoride, etc.;

[0018] The spin-selective layer is a two-dimensional chiral perovskite, such as (R- / S-MBA)2PbI4, (R- / S-MBA)2CuCl4, (R / S-PEA)2PbBr4, (R / S-PEA)CsPbI3, (R / S-MBA)CsPbBr3, etc.

[0019] The electron transport layer material is one of ZnO and ZnO doped with metal cations (such as MgZnO);

[0020] The metal cathode material is aluminum or silver;

[0021] The combined layer of the charge blocking layer and the quantum dot pixel thin film layer is prepared by a transfer method. The specific preparation process is as follows: first, a PDMS stamp with a concave structure on the surface is prepared; the charge blocking layer material is adsorbed on the top of the PDMS concave structure by an LB film forming process; then, the PDMS stamp is attached to the hole transport layer; the PDMS stamp is heated and separated to form a honeycomb-shaped charge blocking layer on the hole transport layer; finally, a quantum dot solution is evenly coated on the charge blocking layer by a spin coating method, so that the quantum dots are fully filled into the pores of the honeycomb-shaped charge blocking layer thin film, thereby forming a combined layer of the charge blocking layer and the quantum dot pixel thin film layer;

[0022] Compared with the existing technology, the beneficial effects of the present invention are: combining the high-resolution quantum dot pixels of the LB process with the CISS effect of chiral perovskite to achieve high-resolution circularly polarized luminescence in the absence of an external magnetic field, filling the gap in the lack of polarization function in high-resolution devices. Its advantages are: (1) Functional integration: while maintaining ultra-high resolution, room-temperature spin-polarized luminescence is introduced for the first time; (2) Process compatibility: the spin-coated chiral perovskite layer does not require complex modification and is compatible with the existing LB-TP process; (3) Performance optimization: the honeycomb charge blocking layer suppresses leakage current; (4) Application expansion: providing a solution with both high density and polarization characteristics for near-eye display and optical encryption. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 : Schematic diagram of the structure of an ultra-high-resolution circularly polarized QLED device according to one embodiment of the present invention;

[0024] Figure 2 : A schematic diagram of a transfer process flow diagram of an embodiment of the present invention;

[0025] Figure 3 : Schematic diagram of the preparation of the combined layer of the charge blocking layer and the quantum dot pixel thin film layer according to one embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to specific examples. It should be understood that the following examples are merely illustrative and explain the present invention, but should not be construed as limiting the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0027] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0028] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] The present invention combines the high-resolution quantum dot pixel preparation technology of the LB process with the CISS effect of chiral perovskite to provide a high-performance ultra-high-resolution circularly polarized light-emitting diode preparation method. Figure 1 As shown, a hole injection layer, a hole transport layer, a charge blocking layer and a quantum dot pixel thin film layer combination layer, an electron transport layer, and a metal cathode are sequentially deposited on the ITO layer of the transparent conductive substrate;

[0030] The hole injection layer material is one of thiocyanate ketone (CuSCN), polystyrene sulfonate (PEDOT:PSS), molybdenum oxide (MoO3), tungsten oxide (WO3), and vanadium pentoxide (V2O5);

[0031] The hole transport layer material is one or a mixture of poly[bis(4-phenyl)(4-butylphenyl)amine] (Poly-TPD), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] (TFB), and polyvinylcarbazole (PVK);

[0032] The quantum dot material is one of CdSe, InP, and perovskite;

[0033] The charge blocking layer material can be an organic material, such as polyethylene, polyvinyl chloride, etc., or an inorganic material, such as nano-silicon dioxide, sodium yttrium fluoride, etc.;

[0034] The spin-selective layer is a two-dimensional chiral perovskite, such as (R- / S-MBA)2PbI4, (R- / S-MBA)2CuCl4, (R / S-PEA)2PbBr4, (R / S-PEA)CsPbI3, (R / S-MBA)CsPbBr3, etc.

[0035] The electron transport layer material is one of ZnO and ZnO doped with metal cations (such as MgZnO);

[0036] The metal cathode material is aluminum or silver;

[0037] The charge blocking layer and the quantum dot pixel film layer combination layer are prepared by transfer printing combined with spin coating method, such as Figure 2 As shown, the specific steps include:

[0038] Step 1: First, prepare a polydimethylsiloxane (PDMS) stamp with a concave structure on the surface;

[0039] Step 2: forming a single-layer charge blocking layer LB film on an LB film drawing machine;

[0040] Step 3: Use a PDMS stamp with a concave structure on the surface to remove the charge blocking layer LB film so that the charge blocking layer is picked up on the top of the concave structure;

[0041] Step 4: Laminating the above stamp onto the hole transport layer, heating the PDMS stamp for 10 minutes, and peeling the stamp to form a honeycomb charge blocking layer on the hole transport layer;

[0042] Step 5: Spin-coating the quantum dot solution onto the honeycomb-shaped charge blocking layer so that the quantum dots are evenly filled in the honeycomb to achieve quantum dot pixelation;

[0043] Step 6: Anneal the pixelated quantum dots on the hole transport layer at 80° C. for 5 min.

[0044] This method uses a transfer printing process to create high-resolution quantum dot pixels on a target substrate. By precisely controlling the arrangement and distribution of the quantum dots, a uniform and high-density pixel array is formed. Subsequently, a two-dimensional chiral perovskite film is spin-coated on the quantum dot pixels, leveraging the chirality-induced spin selectivity (CISS) effect to achieve efficient circularly polarized luminescence.

[0045] The following are specific embodiments of the present invention.

[0046] Example 1:

[0047] The process flow diagram of preparing ultra-high resolution circularly polarized QLED by transfer printing combined with spin coating is shown in the figure. Figure 1 The specific steps include:

[0048] (1) Preparation of a PDMS stamp with a concave surface structure: First, a template with a cylindrical protrusion structure of 400 nm in diameter and 150 nm in height was made on a silicon wafer using photolithography. Then, the PDMS precursor and curing agent were mixed in a certain ratio (usually a mass ratio of 10:1) and degassed under a vacuum environment. The degassed PDMS mixture was slowly poured onto the modified silicon template to ensure that the PDMS was fully filled into the grooves between the cylindrical protrusions. It was then annealed at 80°C for 1 h to solidify the PDMS mixture. Finally, the solidified PDMS was separated from the template. The PDMS stamp area was 0.9 cm 2 , thickness is 0.4 mm;

[0049] (2) Preparation of a honeycomb charge blocking layer: Sodium yttrium fluoride is dispersed in n-hexane to prepare a solution with a concentration of 3 mg / mL. A dense single-layer sodium yttrium fluoride LB film is then generated using an LB film drawing machine. A PDMS stamp with a concave structure on the surface is then adhered to the sodium yttrium fluoride LB film so that the sodium yttrium fluoride is picked up to the top of the concave structure. The above stamp is then attached to the hole transport layer, the stamp is heated at 80°C for 5 min, and the PDMS stamp is peeled off, so that sodium yttrium fluoride forms a honeycomb charge blocking layer on the hole transport layer;

[0050] (3) Preparation of pixelated quantum dot layer: Red CdSe quantum dots with a wavelength of 630 nm and a half-peak width of 20 nm were dispersed in n-octane to prepare a solution with a concentration of 30 mg / mL. The solution was then spin-coated using a spunbond at a speed of 3000 rpm for 30 s to uniformly fill the honeycomb-shaped charge blocking layer with the quantum dot solution, forming quantum dot pixels. Figure 2 Schematic diagram of the preparation process of the combined layer of the charge blocking layer and the quantum dot pixel thin film layer;

[0051] (4) Preparation of spin-selective layer: chiral perovskite (R- / S-MBA)2PbI4 was dispersed in DMF solvent to prepare a solution with a concentration of 30 mg / mL, and then spin-coated using a spin coater at a speed of 4000 rpm and a spin coating time of 45 s.

[0052] Figure 3The structure of an ultra-high-resolution circularly polarized QLED device is shown, consisting of an ITO layer, a hole injection layer, a hole transport layer, a charge blocking layer combined with a quantum dot pixel film layer, a spin selection layer, an electron transport layer, and a metal cathode. The hole injection layer is made of PEDOT:PSS, and the hole transport layer is made of TFB, both of which are spin-coated at 3000 rpm for 30 seconds. The electron transport layer is made of metal-ion-doped MgZnO, which is spin-coated at 2000 rpm for 40 seconds. The metal cathode is a 100 nm thick Ag electrode deposited using a vacuum coating machine.

[0053] Example 2:

[0054] The process flow diagram of preparing ultra-high resolution circularly polarized QLED by transfer printing combined with spin coating is shown in the figure. Figure 1 The specific steps include:

[0055] (1) Preparation of a PDMS stamp with a concave surface structure: First, a template with a cylindrical convex structure of 400 nm in diameter and 150 nm in height was made on a silicon wafer using photolithography. Then, the PDMS precursor and curing agent were mixed in a certain ratio (usually a mass ratio of 10:1) and degassed under a vacuum environment. The degassed PDMS mixture was slowly poured onto the modified silicon template to ensure that the PDMS was fully filled into the grooves between the cylindrical protrusions. It was then annealed at 80°C for 1 h to solidify the PDMS mixture. Finally, the solidified PDMS was separated from the template. The PDMS stamp area was 0.9 cm 2 , thickness is 0.4 mm;

[0056] (2) Preparation of a honeycomb charge blocking layer: Sodium yttrium fluoride is dispersed in n-hexane to prepare a solution with a concentration of 3 mg / mL. A dense single-layer sodium yttrium fluoride LB film is then generated using an LB film drawing machine. A PDMS stamp with a concave structure on the surface is then adhered to the sodium yttrium fluoride LB film so that the sodium yttrium fluoride is picked up to the top of the concave structure. The above stamp is then attached to the hole transport layer, the stamp is heated at 80°C for 5 min, and the PDMS stamp is peeled off, so that sodium yttrium fluoride forms a honeycomb charge blocking layer on the hole transport layer;

[0057] (3) Preparation of pixelated quantum dot layer: Green CdSe quantum dots with a wavelength of 625 nm and a half-peak width of 23 nm were dispersed in n-octane to prepare a solution with a concentration of 20 mg / mL. The solution was then spin-coated using a spunbond at a speed of 3000 rpm for 30 s to uniformly fill the honeycomb-shaped charge blocking layer with the quantum dot solution, forming quantum dot pixels. Figure 2 Schematic diagram of the preparation process of the combined layer of the charge blocking layer and the quantum dot pixel thin film layer;

[0058] (4) Preparation of spin-selective layer: The chiral perovskite (R / S-PEA)2PbBr4 was dispersed in DMF solvent to prepare a solution with a concentration of 30 mg / mL, and then spin-coated into a film using a spin coater at a speed of 4000 rpm and a spin coating time of 45 s.

[0059] Figure 3 The structure of an ultra-high-resolution circularly polarized QLED device is shown, consisting of an ITO layer, a hole injection layer, a hole transport layer, a charge blocking layer combined with a quantum dot pixel film layer, a spin selection layer, an electron transport layer, and a metal cathode. The hole injection layer is made of PEDOT:PSS, and the hole transport layer is made of TFB, both of which are spin-coated at 3000 rpm for 30 seconds. The electron transport layer is made of metal-ion-doped MgZnO, which is spin-coated at 2000 rpm for 40 seconds. The metal cathode is a 100 nm thick Ag electrode deposited using a vacuum coating machine.

[0060] The preparation process of the present invention is simple and the production cost is low. Not only is the preparation speed fast, but also there are no special requirements for the preparation environment. It can be achieved in an atmospheric environment at normal temperature and pressure, meeting the mass production needs of the industry.

Claims

1. A method for preparing a high-performance, ultra-high-resolution circularly polarized light-emitting diode, characterized in that: A hole injection layer, a hole transport layer, a charge blocking layer and a quantum dot pixel thin film layer combination layer, an electron transport layer, and a metal cathode are sequentially deposited on the ITO layer of the transparent conductive substrate; The charge blocking layer and the quantum dot pixel thin film layer combination layer is prepared by a transfer-combined spin coating method, specifically comprising the following steps: Step 1: First, prepare a polydimethylsiloxane (PDMS) stamp with a concave structure on the surface; Step 2: forming a single-layer charge blocking layer LB film on an LB film drawing machine; Step 3: Use a PDMS stamp with a concave structure on the surface to remove the charge blocking layer LB film so that the charge blocking layer is picked up on the top of the concave structure; Step 4: Laminating the above-mentioned stamp onto the hole transport layer, heating the PDMS stamp, and peeling off the stamp to form a honeycomb-shaped charge blocking layer on the hole transport layer; Step 5: Spin-coating the quantum dot solution onto the honeycomb-shaped charge blocking layer so that the quantum dots are evenly filled in the honeycomb to achieve quantum dot pixelation; Step 6: Annealing the pixelated quantum dots on the hole transport layer.

2. The method for preparing a high-performance, ultra-high-resolution circularly polarized light-emitting diode according to claim 1, wherein: The specific preparation method of the honeycomb charge blocking layer is as follows: sodium yttrium fluoride is dispersed in n-hexane to prepare a solution with a concentration of 3 mg / mL, and then a dense single-layer sodium yttrium fluoride LB film is generated by an LB film drawing machine. A PDMS stamp with a concave structure on the surface is then adhered to the sodium yttrium fluoride LB film so that the sodium yttrium fluoride is picked up to the top of the concave structure. The above stamp is then attached to the hole transport layer, the stamp is heated at 80°C for 5 minutes, and the PDMS stamp is peeled off to form a honeycomb charge blocking layer of sodium yttrium fluoride on the hole transport layer.

3. The method for preparing a high-performance, ultra-high-resolution circularly polarized light-emitting diode according to claim 1, characterized in that: The specific method for preparing the pixelated quantum dot layer is as follows: red CdSe quantum dots are dispersed in n-octane to form a solution with a concentration of 30 mg / mL, and then a film is formed using a spin coater at a speed of 3000 rpm and a spin coating time of 30 s, so that the quantum dot solution is evenly filled on the honeycomb-shaped charge blocking layer to form quantum dot pixels.

4. The method for preparing a high-performance, ultra-high-resolution circularly polarized light-emitting diode according to claim 1, wherein: The hole injection layer material is one of thiocyanate CuSCN, polystyrene sulfonate PEDOT:PSS, molybdenum oxide MoO3, tungsten oxide WO3, and vanadium pentoxide V2O5.

5. The method for preparing a high-performance, ultra-high-resolution circularly polarized light-emitting diode according to claim 1, wherein: The hole transport layer material is one or a mixture of poly[bis(4-phenyl)(4-butylphenyl)amine] Poly-TPD, poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)]TFB, and polyvinylcarbazole PVK.

6. The method for preparing a high-performance, ultra-high-resolution circularly polarized light-emitting diode according to claim 1, wherein: The quantum dot material is one of CdSe, InP and perovskite.

7. The method for preparing a high-performance, ultra-high-resolution circularly polarized light-emitting diode according to claim 1, wherein: The charge blocking layer material is an organic material, including polyethylene, polyvinyl chloride, or an inorganic material, including nano silicon dioxide, sodium yttrium fluoride.

8. The method for preparing a high-performance, ultra-high-resolution circularly polarized light-emitting diode according to claim 1, wherein: The spin selection layer is a two-dimensional chiral perovskite, including one of (R- / S-MBA)2PbI4, (R- / S-MBA)2CuCl4, (R / S-PEA)2PbBr4, (R / S-PEA)CsPbI3, and (R / S-MBA)CsPbBr3.

9. The method for preparing a high-performance, ultra-high-resolution circularly polarized light-emitting diode according to claim 1, wherein: The electron transport layer material is one of ZnO and ZnO doped with metal cations.

10. The method for preparing a high-performance, ultra-high-resolution circularly polarized light-emitting diode according to claim 1, wherein: The metal cathode material is aluminum or silver.

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