Method for realizing patterning of perovskite display device

Abstract

The invention discloses a method for realizing patterning of a perovskite display device. The structure of the perovskite display device is ITO / a transmission layer I / a perovskite layer / a transmission layer II / a metal electrode. According to the method, a transmission layer is processed through femtosecond laser, molecules of the transmission layer in a processing area are inactivated, the carrier transmission capacity is lost, then a perovskite thin film is deposited on the processed transmission layer, and a complete device structure is prepared. The method has the remarkable advantages that firstly, the method is high in universality and adapts to various transmission layer materials, and machining parameters do not need to be repeatedly debugged for different perovskite materials; secondly, a mask is not needed, the cost is low, the flexibility is high, and the pixel resolution is quickly adjusted through a preset processing path and laser parameters; and thirdly, large-area (10 * 10 < m-2 >), ultra-fast scanning speed (1000 m / s) and ultra-high resolution (10000 PI) processing can be realized. And an effective technical strategy is provided for patterning the perovskite display.

Description

Technical Field

[0001] This invention relates to the field of display technology, and more specifically to a method for fabricating patterned perovskite light-emitting devices. Background Technology

[0002] Display technology has become a core carrier for information acquisition and interaction in modern society, and its application scenarios are constantly expanding with the rapid development of emerging fields such as wearable devices and near-eye displays (such as AR / VR). Against this backdrop, the market has put forward clear and urgent demands for performance upgrades in display devices, specifically the pursuit of higher resolution, wider color gamut, and greater flexibility. A key prerequisite for achieving this type of high-performance pixelated display lies in the high-precision, highly controllable patterning of the device's luminescent or functional layers. However, current mainstream pixelation patterning technologies still have significant bottlenecks, making it difficult to meet these demands. These technologies mainly include inkjet printing, photolithography, nanoimprinting, and transfer printing. Inkjet printing has stringent requirements for ink dispersion and viscosity, and pixel resolution is limited by the minimum volume of the ejected ink droplets, making it difficult to break through micron-level precision. Photolithography and nanoimprinting are highly dependent on masks; not only is mask preparation cost high, but pixel size is also limited by mask precision, making it impossible to flexibly adapt to different resolution requirements. Transfer printing technology is prone to surface contamination during processing, causing scratches or contamination of the functional layer, leading to a significant reduction in yield. More critically, most existing research focuses on "directly processing the emissive layer" to achieve efficient patterning. However, this approach has inherent drawbacks: emissive materials (such as perovskite quantum dots and organic materials) have weak chemical and thermal stability, and direct processing (such as traditional lasers and mechanical contact) easily leads to material failure and luminous efficiency degradation. Furthermore, the area where the emissive layer is removed lacks a carrier-blocking structure, which significantly exacerbates leakage current problems in the device, ultimately severely restricting the efficiency and stability of display devices. Therefore, developing a novel patterning processing technology that uses the functional layer as the processing target and combines maskless, low-cost, highly universal, and low-damage characteristics, can avoid the defects of direct processing of the emissive layer and overcome the bottlenecks of traditional technologies. This has become a core direction for meeting the needs of display technology upgrades and has significant research significance and enormous application value.

[0003] Specifically, the processing advantages of femtosecond lasers are highly compatible with the requirements for functional layer patterning, and their pulse width can be compressed to the femtosecond level (10^6). -15 (seconds), can precisely focus high energy on a local area of ​​the transport layer within a timescale much faster than the thermal diffusion of the material. This only causes the material in that area to become deactivated and break the carrier transport path due to the instantaneous energy accumulation, without causing thermal damage to the adjacent light-emitting layer, substrate or other functional layers. This precisely solves the core pain point of "traditional processing damaging light-emitting materials".

[0004] More importantly, this technology is significantly more versatile than traditional processes. Unlike photolithography, it eliminates the need for repeated adjustments to masks and process parameters for perovskite layers of different materials. Only fine-tuning of laser energy, scanning speed, and scanning path is required for adaptation, drastically reducing the processing cost and debugging cycle of multi-material devices. Furthermore, the "local deactivation" structure of the processed transport layer forms a natural carrier blocking boundary, effectively suppressing leakage current. Compared to the "direct processing of the emitting layer" approach, the luminous efficiency and stability of the device can be improved by 20%-30%.

[0005] From an application perspective, this technology not only meets the high-resolution requirements of AR / VR near-eye displays but also adapts to the curved surface processing scenarios of flexible wearable devices. Furthermore, its maskless and low-cost characteristics make it suitable for mass production. This patterning scheme, centered on ultrafast laser processing of functional layers, provides key technological support for the industrialization of next-generation high-performance display devices and has significant application potential in display applications. Summary of the Invention

[0006] To address the shortcomings of existing technologies, a method for patterning perovskite display devices is provided, achieving pixelation processing that is "highly versatile, fast, high-resolution, low-cost, and covers a large area".

[0007] The technical solution adopted to achieve the purpose of this invention is:

[0008] This invention provides a method for patterning perovskite display devices, comprising the following key steps:

[0009] 1. Device structure and material composition

[0010] The perovskite patterned display device of this invention has a layered stacked structure, consisting of, from top to bottom: an ITO transparent conductive layer, a hole transport layer, a perovskite light-emitting layer, an electron transport layer, and a metal electrode. The materials and key parameters of each layer are as follows:

[0011] (1) ITO transparent conductive layer: sheet resistance 6Ω, thickness 185 nm, with 13.5×10 mm retained in the center, prepared by magnetron sputtering process;

[0012] (2) Transport layer: The materials are selected from poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] (TFB), poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), 4,4'-bis-(carbazole-9-yl)biphenyl (CBP), poly(9-vinylcarbazole) (PVK), zinc oxide (ZnO), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), and 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazine (PO-T2T), and are prepared by spin coating or thermal evaporation process;

[0013] (3) Perovskite luminescent layer: The perovskite material is selected from CsPbX3; FAPbX3, MAPbX3 (X=Cl, Br, I); the emission wavelength is adjusted by controlling the ratio of halogens (Cl / Br / I);

[0014] (4) Metal electrode: The metal electrode material is selected from Al, Ag and Au with a thickness of 80 nm and is prepared by high vacuum thermal evaporation process.

[0015] 2. Femtosecond processing and transmission

[0016] This invention achieves pixelated light emission by selectively processing the transport layer of a perovskite display device using femtosecond lasers. The specific steps are as follows:

[0017] (1) Pre-fabrication of device semi-finished products: According to the above layered device structure, ITO transparent electrode / transport layer I is prepared in sequence to obtain a semi-finished device without perovskite layer, transport layer II and metal electrode.

[0018] (2) Femtosecond laser parameter setting: The pattern to be processed, i.e. the path of laser movement, is drawn on the computer in advance. Then, the laser processing parameters are set: laser wavelength 532 nm, pulse width 150 fs, repetition frequency 5 kHz, energy density 30 μJ / cm² (optional 50-200 μJ / cm²), scanning speed 60 mm / s (optional 1-1000 mm / s continuously adjustable), and spot diameter 50-2000 nm;

[0019] (3) Selective processing of transport layer I: The semi-finished device is fixed on a precision displacement platform, and the laser is controlled to focus on the surface of the hole transport layer. The laser energy only causes the hole transport layer material in the focused area to be deactivated instantaneously, destroying the carrier transport path and losing the hole transport capability. The device is processed according to a preset pattern (pixel array or pattern), and the unirradiated area retains the transport function.

[0020] (4) Subsequent fabrication: After processing, transport layer II and metal electrodes are fabricated according to the layered structure to obtain the final perovskite patterned display device. In the unprocessed area, the carrier transport is normal in the “hole transport layer → light emission layer → electron transport layer”, and electrons and holes recombine in the perovskite layer to emit light (forming bright pixels); in the processed inactive area, the carriers cannot recombine due to the blockage of hole transport (forming dark pixels), and finally the pixelation display is realized.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. No mask required, low cost and high flexibility: Eliminates the mask design and fabrication costs of photolithography / nanoimprinting, and pixel resolution can be quickly adjusted through preset processing paths and laser parameters;

[0023] 2. High versatility: It is compatible with a variety of transport layer materials without the need for repeated adjustments to processing parameters for different perovskite materials. It can fabricate monochrome (red / green / blue) or multicolor display devices, while the resolution can be continuously adjusted below 10,000 PPI and is compatible with a variety of substrates.

[0024] 3. Large-area, high-speed processing: Femtosecond laser processing speed can reach 1000 mm / s, with a processing area of ​​10×10 cm. -2 It can achieve large-area rapid processing with a high yield rate. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the process for fabricating the patterned perovskite display device in Example 1;

[0026] Figure 2 The image shown is an electroluminescent photograph of the patterned display device of Example 1. The image shown is the letter BJUT, where the transport layer I is PTAA and the perovskite layer is CsPbBr3.

[0027] Figure 3 This is an electroluminescent photograph of the patterned display device of Example 2. The image shown is by Yan Xiaobei of Beijing University of Technology, where the transport layer I is PVK and the perovskite layer is FAPb(Br) 1.5 Cl 1.5 );

[0028] Figure 4 This is an electroluminescent photograph of the patterned display device of Example 3. The image shown is the emblem of Beijing University of Technology, where the transport layer I is TFB and the perovskite layer is MAPb(Br) 1.5 I 1.5 ); Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments and figures.

[0030] A method for fabricating patterned perovskite light-emitting devices includes the following steps:

[0031] Example 1

[0032] (1) ITO Cleaning: Cleaning impurities on the ITO surface makes it easier for the hole transport layer film to adhere. ITO was ultrasonically treated for 15 minutes sequentially with toluene, acetone, isopropanol, anhydrous ethanol, and deionized water. Finally, it was stored in anhydrous ethanol. Before use, the surface liquid of the ITO was first dried with an air gun, and after complete drying, it was placed in a UV cleaning machine for 15 minutes.

[0033] (2) Preparation of transport layer I: Prepare 8 mg / ml solution in chlorobenzene solvent. -1 The PTAA solution was spin-coated onto ITO at a rate of 2000 r / min for 60 s to form a film. It was then annealed on a 120℃ heating plate for 15 min.

[0034] (3) Patterning process of the transport layer: The transport layer substrate is placed on a displacement platform, and the sample position is adjusted up and down to ensure that the sample surface is on the focal plane of the laser processing system. The image of BJUT is pre-drawn on the computer, and the power of the femtosecond laser is set to 30 mW, the scanning rate to 6 mm / s, and the repetition rate to 5 kHz. During processing, the femtosecond laser will move along the pre-designed image path to achieve the purpose of processing transport layer I;

[0035] (4) Preparation of CsPbBr3 thin film: CsPbBr3 solution was pipetted onto the patterned transport layer and uniformly spin-coated at 1000 r / min to form the film. All of the above was completed in a glove box;

[0036] (5) Preparation of transport layer II: 40 nm of TPBi was deposited on the perovskite layer in vacuum at a rate of 0.8 Å / s;

[0037] (6) Preparation of Al electrode: 80 nm of Al was deposited on transport layer II in vacuum at a rate of 3 Å / s;

[0038] (7) The patterned device obtained in (6) can be lit by connecting an external power supply to obtain a patterned display device.

[0039] Example 2

[0040] (1) ITO Cleaning: Cleaning impurities on the ITO surface makes it easier for the hole transport layer film to adhere. ITO was ultrasonically treated for 15 minutes sequentially with toluene, acetone, isopropanol, anhydrous ethanol, and deionized water. Finally, it was stored in anhydrous ethanol. Before use, the surface liquid of the ITO was first dried with an air gun, and after complete drying, it was placed in a UV cleaning machine for 15 minutes.

[0041] (2) Preparation of transport layer I: Prepare 15 mg / ml solution in chlorobenzene solvent. -1 The PVK solution was spin-coated onto ITO at a rate of 1500 r / min for 60 s to form a film. It was then annealed on a 120℃ heating plate for 15 min.

[0042] (3) Patterning process of the transport layer: The transport layer substrate is placed on a displacement platform, and the sample position is adjusted vertically to ensure that the sample surface is on the focal plane of the laser processing system. An image of Yan Xiaobei from Beijing University of Technology is pre-drawn on the computer, and the power of the femtosecond laser is set to 40 mW, the scanning rate to 20 mm / s, and the repetition rate to 5 kHz. During processing, the femtosecond laser will move along the pre-designed image path to achieve the purpose of processing transport layer I;

[0043] (4) FAPb(Br 1.5 Cl 1.5 Thin film preparation: FAPb(Br) was pipetted into the film. 1.5 Cl 1.5 The solution was uniformly spin-coated onto the patterned transport layer at 1000 r / min to form a film. All of the above was performed in a glove box.

[0044] (5) Preparation of transport layer II: 40 nm of TPBi was deposited on the perovskite layer in vacuum at a rate of 0.8 Å / s;

[0045] (6) Preparation of Al electrode: 80 nm of Al was deposited on transport layer II in vacuum at a rate of 3 Å / s;

[0046] (7) The patterned device obtained in (6) can be lit by connecting an external power supply to obtain a patterned display device.

[0047] Example 3

[0048] (1) ITO Cleaning: Cleaning impurities on the ITO surface makes it easier for the hole transport layer film to adhere. ITO was ultrasonically treated for 15 minutes sequentially with toluene, acetone, isopropanol, anhydrous ethanol, and deionized water. Finally, it was stored in anhydrous ethanol. Before use, the surface liquid of the ITO was first dried with an air gun, and after complete drying, it was placed in a UV cleaning machine for 15 minutes.

[0049] (2) Preparation of transport layer I: Prepare 15 mg / ml solution in chlorobenzene solvent. -1 The TFB solution was spin-coated onto ITO at a rate of 4000 r / min for 60 s to form a film. It was then annealed on a 120℃ heating plate for 15 min.

[0050] (3) Patterning process of the transport layer: The transport layer substrate is placed on a displacement platform, and the sample position is adjusted vertically to ensure that the sample surface is on the focal plane of the laser processing system. An image of Yan Xiaobei from Beijing University of Technology is pre-drawn on the computer, and the power of the femtosecond laser is set to 40 mW, the scanning rate to 50 mm / s, and the repetition rate to 5 kHz. During processing, the femtosecond laser will move along the pre-designed image path to achieve the purpose of processing transport layer I;

[0051] (4)MAPb(Br 1.5 I 1.5 Thin film preparation: MAPb(Br) was pipetted into the film. 1.5 I 1.5 The solution was uniformly spin-coated onto the patterned transport layer at 1200 r / min to form a film. All of the above was completed in a glove box.

[0052] (5) Preparation of transport layer II: 40 nm of TPBi was deposited on the perovskite layer in vacuum at a rate of 0.8 Å / s;

[0053] (6) Preparation of Al electrode: 80 nm of Al was deposited on transport layer II in vacuum at a rate of 3 Å / s;

[0054] (7) The patterned device obtained in (6) can be lit by connecting an external power supply to obtain a patterned display device.

Claims

1. A method for patterning a perovskite display device, wherein the perovskite display device has the structure of ITO / transport layer I / perovskite layer / transport layer II / metal electrode, wherein the material of transport layer I / II is selected from poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] (TFB), and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). 4,4'-bis-(carbazole-9-yl)biphenyl (CBP), poly(9-vinylcarbazole) (PVK), zinc oxide (ZnO), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazine (PO-T2T); wherein the perovskite material is selected from CsPbX3; FAPbX3, MAPbX3 (X=Cl, Br, I); the metal electrode material is selected from Al, Ag, Au; characterized in that, This method uses femtosecond lasers to process the transport layer, deactivating the molecules in the processed region and causing them to lose their carrier transport capabilities. Next, a perovskite thin film is deposited on the processed transport layer to fabricate a complete device structure. Because the processed transport layer region is deactivated, electrons and holes cannot recombine in the corresponding perovskite layer region, ultimately achieving the patterning of perovskite light-emitting devices.

2. The method for fabricating perovskite patterned display devices based on femtosecond laser processing technology according to claim 1, comprising the following steps: Step 1, ITO cleaning: Clean impurities from the ITO surface; use toluene, acetone, isopropanol, anhydrous ethanol, and deionized water to ultrasonically treat the ITO in sequence, and store it in anhydrous ethanol; Step 2, Preparation of the transport layer: Prepare 5-20 mg / ml -1 Hole transport layer material; spin-coated onto ITO at a rate of 1000-3000 r / min for 60 s to form a film; then annealed on a heating stage at 120℃; Step 3, Transmission Layer Patterning Process: The transmission layer substrate is placed on a displacement platform, and the sample position is adjusted up and down to ensure that the sample surface is on the focal plane of the laser processing system. The image is pre-drawn on the computer; during processing, the femtosecond laser will move along the pre-designed image path to achieve the purpose of processing the transmission layer. Step 4, preparation of perovskite thin film: Use a pipette to pick up the perovskite solution and spin-coat it evenly on the patterned transport layer. Spin-coat the film at 1000-3000 r / min and place it on a heating stage at 60 ℃ for annealing. Step 5, fabrication of metal electrodes: Patterned devices are fabricated by vapor deposition on perovskite thin films in a vacuum at rates of 1-5 Å / s. Step 6: Turn on the external power supply of the patterning device from step 5 to obtain the patterned display device.

3. In the method for preparing perovskite patterned display devices based on femtosecond laser processing technology according to claim 2, in step 1, the surface liquid of ITO is first dried with an air gun. After it is completely dry, it is placed in a UV light cleaning machine for 15 minutes and then placed in a clean box for later use.

4. In the method for fabricating perovskite patterned display devices based on femtosecond laser processing technology according to claim 1, in step 3, the power of the femtosecond laser is set to 1-50 mW, the scanning rate to 1-100 mm / s, and the repetition rate to 5 kHz.

5. The method for fabricating perovskite patterned display devices based on femtosecond laser processing technology according to claim 1, wherein step 4 is performed in a glove box.

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