Large-area perovskite light-emitting polycrystalline thin film backlight module, preparation method thereof and LCD backlight module

Abstract

This application relates to a large-area perovskite luminescent polycrystalline thin film backlight module and its fabrication method, as well as an LCD backlight module, comprising the following steps: preparing green and red perovskite precursor solutions; preparing spacer layer precursor solutions; preparing green perovskite polycrystalline thin films by a blade coating method and post-processing; preparing spacer layers by a blade coating method; preparing red perovskite polycrystalline thin films by a blade coating method and post-processing; encapsulating with a water-oxygen barrier film; and assembling the LCD backlight module. This application can fabricate dual-color stacked large-area perovskite luminescent polycrystalline thin films, which, when applied to LCD backlight structures, offer advantages such as low cost and high color gamut.

Description

Technical Field

[0001] This application relates to the field of luminescent materials and display technology, and in particular to a large-area perovskite luminescent polycrystalline thin film backlight module and its preparation method, as well as an LCD backlight module. Background Technology

[0002] With the continuous development of display technology, the demand for high-performance displays is constantly increasing. People are increasingly pursuing displays with higher color gamuts and brightness, while traditional liquid crystal displays (LCDs) have relatively low color gamuts and brightness, gradually failing to meet the needs of high-end displays. In contrast, emerging display technologies such as organic light-emitting diodes (OLEDs) and Mini LEDs offer many performance advantages, posing a challenge to LCD technology. However, due to their complex processes, low yield rates, and short lifespans, their costs are extremely high, and large-area displays are difficult to develop. In contrast, LCD displays offer advantages such as low cost, long lifespan, and ease of large-area production. If traditional LCD display technology can be improved to enhance its color gamut and brightness, LCD displays can meet the demand for low-cost, high-performance displays.

[0003] Traditional phosphor pink conversion layers suffer from low color purity and low light conversion efficiency. Currently, quantum dot film solutions are another method to improve LCD backlight performance. A common approach is to use blue LED chips with cadmium selenide or indium phosphide red and green quantum dot films. However, the preparation process of quantum dots in this approach is relatively complex, and the EU standard has strict requirements on cadmium content, making it difficult to promote.

[0004] Perovskite is a novel semiconductor optoelectronic material. As a light-emitting material, it possesses advantages such as tunable emission wavelength, wide color gamut, narrow half-maximum width at half-maximum (HWHM), high photoluminescence efficiency, low cost, and simple fabrication process, making it suitable for developing high-performance displays. However, the efficiency and stability of current perovskite LCD backlights are not yet ideal, thus necessitating optimization of the fabrication process for perovskite luminescent thin films. Summary of the Invention

[0005] This application provides a large-area perovskite light-emitting polycrystalline thin-film backlight module and its preparation method, as well as an LCD backlight module, to solve the problems of low light conversion efficiency, insufficient brightness, and low color gamut in perovskite LCD light-emitting devices in related technologies.

[0006] The specific technical solution provided in this application is as follows:

[0007] In a first aspect, this application provides a method for fabricating a large-area perovskite light-emitting polycrystalline thin-film backlight module, comprising the following steps:

[0008] PbBr2, CsBr and PEABr were dissolved in an organic solvent, and crown ether was added to obtain a green light perovskite precursor solution.

[0009] CsBr, CsI, PbI2 and PEAI were dissolved in an organic solvent, and crown ether was added to obtain a red light perovskite precursor solution.

[0010] Preparation of spacer layer precursor solution;

[0011] The green light perovskite precursor solution was coated onto a transparent substrate, annealed, and treated with water and oxygen to obtain a green light emitting polycrystalline perovskite film.

[0012] The spacer layer precursor solution was coated onto a perovskite green light emitting polycrystalline thin film and then annealed to obtain the spacer layer.

[0013] The red light perovskite precursor solution was coated onto the spacer layer, annealed, and treated with water and oxygen to obtain a perovskite red light emitting polycrystalline thin film.

[0014] A water and oxygen barrier film is encapsulated on the surface of a perovskite red-luminescent polycrystalline thin film.

[0015] In some embodiments, the molar ratio of PbBr2, CsBr and PEABr is 1:1:0.4;

[0016] And / or, the molar ratio of CsBr, CsI, PbI2 and PEAI is 0.9:0.1:1:0.6.

[0017] In some embodiments, the organic solvent is characterized in that it comprises one or more of dimethylformamide, dimethyl sulfoxide, dimercaptoethanol, and γ-butyrolactone.

[0018] In some embodiments, the annealing temperature of the green perovskite film is 60-100°C, and the annealing time is 5-20 min;

[0019] And / or, the annealing temperature of the red light perovskite film is 60-100℃, and the annealing time is 5-20min;

[0020] And / or, “water and oxygen treatment” includes the following steps:

[0021] After annealing, expose to air with a humidity of 30-60%RH for 3-5 minutes.

[0022] In some embodiments, air knife drying is used during the coating process, and the gas used for air knife drying is nitrogen gas with a temperature of 50-80°C and a flow rate of 5-40 L / min.

[0023] In some embodiments, the temperature during coating is 25-60°C, and the coating speed is 5-30 mm / s.

[0024] In some embodiments, the water and oxygen barrier film is one or more of polymethyl methacrylate, polycarbonate, polyethylene terephthalate, polypropylene, polyvinyl chloride, and polystyrene.

[0025] In some embodiments, "encapsulating a water-oxygen barrier film on the surface of a perovskite red-luminescent polycrystalline thin film" includes the following steps:

[0026] UV-curable adhesive is applied to the edge of the water-oxygen barrier film, and then it is attached to the surface of the perovskite red-luminescent polycrystalline film and cured under UV light.

[0027] Secondly, this application provides a large-area perovskite light-emitting polycrystalline thin film backlight module, which is prepared by the method described in the first aspect.

[0028] Thirdly, this application provides an LCD backlight module, including a reflective film, a light guide plate, a diffusion film, and a large-area perovskite light-emitting polycrystalline thin film backlight module as described in the second aspect, which are stacked sequentially.

[0029] The large-area perovskite luminescent polycrystalline thin film backlight module includes a transparent substrate, a perovskite green luminescent polycrystalline thin film, a spacer layer, a perovskite red luminescent polycrystalline thin film, and a water and oxygen barrier film stacked sequentially, with the transparent substrate disposed on the surface of the diffusion film.

[0030] The beneficial effects of the technical solution provided in this application include:

[0031] (1) This application can obtain green light conversion material with PLQY of more than 90% by preparing CsPbBr3 perovskite green light emitting polycrystalline thin film. By adding PEABr, a quasi-two-dimensional perovskite structure is obtained and its emission peak is tuned to 525nm. By adding crown ether, the brightness and stability of the perovskite thin film are improved.

[0032] By preparing CsPb(Br) 0.3 I 0.7 )3 Perovskite red-emitting polycrystalline thin film: A red light conversion material with a PLQY of over 60% was successfully prepared. Quasi-two-dimensional perovskite structure was obtained by adding PEAI, and its emission peak was tuned to 650nm. The brightness and stability of the perovskite thin film were improved by adding crown ether.

[0033] (2) This application uses a blade coating method to prepare perovskite luminescent thin films, and prepares 1m thick films. 2 The light-emitting thin film only requires 5-10 mL of organic solvent, compared to at least 35-200 mL of organic solvent required for quantum dot preparation. This can save a significant amount of organic solvent, thereby reducing production costs and minimizing environmental pollution.

[0034] (3) In this application, a spacer layer is provided between two perovskite light-emitting films, which can effectively isolate the influence between the two perovskite layers, avoid the dissolution of the first perovskite layer when the second perovskite layer is coated, and also avoid ion migration between the two perovskite layers. The spacer layer prepared by the coating method can be tightly bonded to the perovskite film. Compared with the directly attached spacer layer, the bonding is tighter and the thickness is lower.

[0035] (4) This application uses a water-oxygen barrier film to avoid the corrosive effect of water and oxygen on perovskite, so that the perovskite luminescent film structure has high stability.

[0036] (5) The LCD backlight module structure provided by the present invention uses the above method to prepare a large area perovskite light-emitting polycrystalline thin film module, which can improve the brightness of the LCD backlight module and greatly broaden the color gamut of the LCD backlight module so as to meet the Rec.2020 color gamut coverage requirements and have high color purity.

[0037] (6) In this application, after the perovskite film is annealed, the perovskite film is placed in the air for water and oxygen treatment. The water and oxygen cause the perovskite crystals to recrystallize, which improves the crystal quality and luminescence of the perovskite film. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of the LCD backlight module provided in the embodiments of this application;

[0040] Figure 2 This is a white light spectrum diagram of the LCD backlight module provided in Embodiment 1 of this application;

[0041] Figure 3 This is a color gamut diagram of the LCD backlight module provided in Embodiment 1 of this application;

[0042] Figure 4 Photographs of the perovskite green light thin films provided in Example 1 and Comparative Example 1 of this application.

[0043] Figure 1 In the middle: 1. Transparent substrate; 2. Perovskite green light emitting polycrystalline film; 3. Spacer layer; 4. Perovskite red light emitting polycrystalline film; 5. Water and oxygen barrier film; 6. UV curable adhesive; 7. Reflective film; 8. Light guide plate; 9. Blue LED beads; 10. Reflective structure; 11. Diffuse film; 12. Light shielding structure. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] In a first aspect, embodiments of this application provide a method for fabricating a large-area perovskite luminescent polycrystalline thin-film backlight module, comprising the following steps:

[0046] PbBr2, CsBr and PEABr were dissolved in an organic solvent, and crown ether was added to obtain a green light perovskite precursor solution.

[0047] CsBr, CsI, PbI2 and PEAI were dissolved in an organic solvent, and crown ether was added to obtain a red light perovskite precursor solution.

[0048] Preparation of spacer layer precursor solution;

[0049] The green light perovskite precursor solution was coated onto a transparent substrate, annealed, and treated with water and oxygen to obtain a green light emitting polycrystalline perovskite film.

[0050] The spacer layer precursor solution was coated onto a perovskite green light emitting polycrystalline thin film and then annealed to obtain the spacer layer.

[0051] The red light perovskite precursor solution was coated onto the spacer layer, annealed, and treated with water and oxygen to obtain a perovskite red light emitting polycrystalline thin film.

[0052] A water and oxygen barrier film is encapsulated on the surface of a perovskite red-luminescent polycrystalline thin film.

[0053] In a preferred embodiment, the transparent substrate further includes a pretreatment step before the green light perovskite precursor solution is coated, as follows:

[0054] The transparent substrate was cleaned in acetone, isopropanol and anhydrous ethanol in ultrasonic cleaning agents for 15 minutes each, and then dried with a nitrogen gun.

[0055] Specifically, the "preparation of spacer layer precursor solution" includes the following steps:

[0056] The spacer material was dissolved in chlorobenzene to obtain a spacer precursor solution.

[0057] Furthermore, the spacer material includes one of polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS), and polyvinylidene fluoride (PVDF).

[0058] In some embodiments, the molar ratio of PbBr2, CsBr and PEABr is 1:1:0.4;

[0059] And / or, the molar ratio of CsBr, CsI, PbI2 and PEAI is 0.9:0.1:1:0.6.

[0060] Specifically, PEABr is phenylethyl ammonium bromide, and PEAI is phenylethyl ammonium iodide.

[0061] In some embodiments, the organic solvent includes one or more of dimethylformamide, dimethyl sulfoxide, dimercaptoethanol, and γ-butyrolactone.

[0062] The solvents mentioned above have the characteristics of low coordination and high volatility, which can accelerate the evaporation rate of the solvent during the film formation process, enabling the perovskite to nucleate and crystallize rapidly.

[0063] In some embodiments, the annealing temperature of the green perovskite film is 60-100°C, and the annealing time is 5-20 min;

[0064] And / or, the annealing temperature of the red light perovskite film is 60-100℃, and the annealing time is 5-20min.

[0065] In the preparation method provided in this application, the annealing temperature of the perovskite thin film does not need to exceed 100°C. In contrast, the preparation of quantum dot light-emitting thin films requires a temperature of at least 100°C. The low-temperature preparation method of this application is beneficial to improving the safety of the preparation process, reducing the temperature resistance requirements of the substrate material for the prepared film, and saving energy and reducing energy consumption.

[0066] In some embodiments, air knife drying is used during the coating process. The gas used for air knife drying is nitrogen, and the nitrogen has a temperature of 50-80°C and a flow rate of 5-40 L / min.

[0067] This application combines air knife drying during the coating process, which can create a flowing micro-wind on the substrate surface, accelerate solvent evaporation, thereby accelerating perovskite nucleation, promoting perovskite crystallization, and thus obtaining a perovskite luminescent film with smaller and more uniform grains.

[0068] Furthermore, nitrogen drying at 50-80°C is used. The high temperature of nitrogen can increase the temperature of the substrate surface and promote the volatilization of high-boiling-point solvents (e.g., DMSO), which can yield perovskite light-emitting films with better crystallinity.

[0069] Furthermore, after the perovskite film is annealed, it is placed in an air environment with a humidity of 30-60%RH for water and oxygen treatment. The moisture and oxygen in the air can recrystallize the perovskite crystals and passivate surface defects, thereby improving the crystal quality and luminescence brightness of the perovskite film.

[0070] In a preferred embodiment, the distance between the air knife and the transparent substrate is 3-5 cm, the nitrogen flow rate is 15 L / min, the angle between the air knife and the transparent substrate is 60°, and the air direction is towards the front end of the transparent substrate.

[0071] In some embodiments, the temperature during coating is 25-60°C, and the coating speed is 5-30 mm / s.

[0072] Specifically, the coating method includes, but is not limited to, using a coating instrument. Furthermore, the coating instrument includes a worktable and a scraper set on the upper part of the worktable.

[0073] Specifically, the method for applying the coating in this application may include the following steps:

[0074] Vacuum adsorb the transparent substrate onto the table of the coating instrument, set the table temperature to 25-60℃, place the squeegee at the front end of the transparent substrate, and drop the precursor solution into the gap between the squeegee and the transparent substrate. Coat the precursor solution at 5-30mm / s.

[0075] In some embodiments, the water and oxygen barrier film is one or more of polymethyl methacrylate, polycarbonate, polyethylene terephthalate, polypropylene, polyvinyl chloride, and polystyrene.

[0076] Water-oxygen barrier films can effectively prevent water and oxygen from corroding perovskite, thus giving the perovskite luminescent film structure high stability.

[0077] In some embodiments, "encapsulating a water and oxygen barrier film on the surface of a perovskite red-luminescent polycrystalline thin film" includes the following steps:

[0078] UV-curable adhesive is applied to the edge of the water-oxygen barrier film, and then it is attached to the surface of the perovskite red-luminescent polycrystalline film and cured under UV light.

[0079] Specifically, the surface of the UV-curable adhesive is made to adhere to the edge of the transparent substrate so that the UV-curable adhesive, the water and oxygen barrier film, and the transparent substrate form a cavity to seal the perovskite green light-emitting polycrystalline film, the spacer layer, and the perovskite red light-emitting polycrystalline film within the cavity, preventing external water vapor and oxygen from intruding into the perovskite light-emitting polycrystalline film.

[0080] Secondly, this application also provides a large-area perovskite light-emitting polycrystalline thin film backlight module, which is prepared by the method described above.

[0081] See Figure 1 As shown, the large-area perovskite luminescent polycrystalline thin film backlight module prepared by the above method includes a transparent substrate 1, a perovskite green luminescent polycrystalline thin film 2, a spacer layer 3, a perovskite red luminescent polycrystalline thin film 4, and a water and oxygen barrier film 5 stacked together. Ultraviolet light curable adhesive 6 is bonded to the edge between the transparent substrate 1 and the water and oxygen barrier film 5.

[0082] Figure 1 As shown, in a third aspect, this application also provides an LCD backlight module, including a reflective film 7, a light guide plate 8, a diffusion film 11, and a large-area perovskite light-emitting polycrystalline thin film backlight module as described above, which are stacked in sequence.

[0083] The large-area perovskite luminescent polycrystalline thin film backlight module includes a transparent substrate 1, a perovskite green luminescent polycrystalline thin film 2, a spacer layer 3, a perovskite red luminescent polycrystalline thin film 4, and a water and oxygen barrier film 5 stacked sequentially, with the transparent substrate 1 disposed on the surface of the diffusion film 11.

[0084] Blue LED beads 9 and reflective structure 10 are arranged sequentially on both sides of the light guide plate 8.

[0085] In a preferred embodiment, a light-shielding structure 12 is further included. The light-shielding structure 12 is disposed around the reflective film 7 and covers the periphery of the light guide plate 8, the diffusion film 11, and the large-area perovskite light-emitting polycrystalline thin film backlight module.

[0086] The LCD backlight module provided in this application uses blue LED beads as the blue light source. The blue LED beads 9 and the reflective structure 10 are fixed on both sides of the light guide plate 8 so that the blue light is transmitted to the entire plane through the light guide plate 8.

[0087] Furthermore, the reflective structure 10 can be bonded to the periphery of the blue LED beads 9 with an adhesive so that light can only be emitted into the light guide plate 8, forming a composite structure of blue LED light source and light guide plate.

[0088] The reflective film 7 is fixed to the lower surface of the aforementioned blue LED light source-light guide plate composite structure. It prevents light from escaping from below, ensuring that light only exits from the upper surface of the light guide plate 8. The diffuser film 11 is fixedly placed on the upper surface of the light guide plate 8, allowing the light emitted from the light guide plate 8 to diffuse evenly. The large-area perovskite luminescent polycrystalline thin film backlight module is fixedly placed on the upper surface of the diffuser film 11, so that some of the blue light is converted into green and red light, which are then superimposed to form a wide color gamut, high color purity, and high brightness white light. The light-shielding structure 12 is placed around the large-area perovskite luminescent polycrystalline thin film backlight module, serving to block edge light leakage and fix the large-area perovskite luminescent polycrystalline thin film backlight module and the light guide structure.

[0089] The present application will be further described below through specific embodiments.

[0090] Example 1

[0091] See Figure 1 This application provides a large-area perovskite luminescent polycrystalline thin film backlight module, including a transparent substrate 1, a perovskite green luminescent polycrystalline thin film 2, a spacer layer 3, a perovskite red luminescent polycrystalline thin film 4, and a water and oxygen barrier film 5 stacked together. Ultraviolet light curable adhesive 6 is bonded to the edge between the transparent substrate 1 and the water and oxygen barrier film 5.

[0092] The preparation method is as follows:

[0093] (1) Cleaning of transparent substrate

[0094] The transparent substrate was cleaned in an ultrasonic cleaner for 15 minutes with acetone, isopropanol and anhydrous ethanol respectively, and then dried with a nitrogen gun to obtain a clean transparent substrate.

[0095] (2) Preparation of green light perovskite precursor solution

[0096] Weigh the corresponding reagents according to the molar ratio of PbBr2:CsBr:PEABr = 1:1:0.4 and dissolve them in 1 ml of DMSO to prepare a precursor solution with a concentration of 0.1 M. Then add 4 mg of crown ether and shake the solution on a shaker for 6 h to fully dissolve and mix it to obtain the green light perovskite precursor solution.

[0097] (3) Preparation of perovskite green light emitting polycrystalline thin films

[0098] The table temperature of the coating instrument is set to 45℃. The cleaned transparent substrate is vacuum-adsorbed onto the table of the coating instrument. The scalpel is placed at the front end of the transparent substrate. The green perovskite precursor solution is dropped into the gap between the scalpel and the transparent substrate. The green perovskite film is coated on the transparent substrate at a speed of 5 mm / s. The distance between the air knife and the substrate is adjusted to 3 cm, the nitrogen flow rate is 5 L / min, the angle between the air knife and the substrate is 60°, and the air direction is towards the front end of the substrate. The nitrogen is heated to 50℃, and then the air knife is turned on to accelerate the evaporation of the solvent. The transparent substrate is then placed on a 100℃ hot table for annealing for 5 min. The annealed substrate is then placed in a 30%RH air environment for water and oxygen treatment for 5 min to form a green perovskite luminescent polycrystalline film.

[0099] (4) Preparation of spacer layer precursor solution

[0100] Weigh 10 mg PMMA and dissolve it in 1 mL of chlorobenzene solution to prepare a 10 mg / mL spacer precursor solution.

[0101] (5) Preparation of spacer layer

[0102] The transparent substrate, after step (3), is vacuum adsorbed onto the table of the scraper. The table temperature of the scraper is set to 45°C. The scraper is placed at the front end of the transparent substrate. The spacer layer precursor solution is dropped into the gap between the scraper and the transparent substrate. The spacer layer is scraped onto the perovskite green light emitting polycrystalline film at a speed of 10 mm / s. The transparent substrate is then placed on a 60°C hot table for annealing for 10 minutes to form the spacer layer.

[0103] (6) Preparation of red light perovskite precursor solution

[0104] Weigh the corresponding reagents according to the molar ratio of CsBr:CsI:PbI2:PEAI = 0.9:0.1:1:0.6 and dissolve them in 1 ml of DMF to prepare a 0.1 M precursor solution. Then add 5 mg of crown ether and shake the solution on a shaker for 6 hours to fully dissolve and mix, thus obtaining the red light perovskite precursor solution.

[0105] (7) Preparation of perovskite red-luminescent polycrystalline thin films

[0106] The transparent substrate, after step (5), is vacuum adsorbed onto the table of the coating instrument. The table temperature of the coating instrument is set to 45°C. The scalpel is placed at the front end of the transparent substrate. The red light perovskite precursor solution is dropped into the gap between the scalpel and the transparent substrate. The red light perovskite film is coated on the spacer layer at a speed of 10 mm / s. The distance between the air knife and the substrate is adjusted to 5 cm, the nitrogen flow rate is 15 L / min, the angle between the air knife and the substrate is 60°, and the air direction is towards the front end of the substrate. The nitrogen is heated to 50°C, and the air knife is turned on to accelerate the evaporation of the solvent. The transparent substrate is then placed on a 100°C hot table for annealing for 20 min. The annealed substrate is placed in an air environment with 30%RH for water and oxygen treatment for 3 min to form a perovskite red light emitting polycrystalline film.

[0107] (8) Encapsulation of perovskite thin films

[0108] Apply a small amount of UV-curable adhesive in strips along the four edges of the PET water-oxygen barrier film, then attach it to the transparent substrate, ensuring the water-oxygen barrier film completely covers the perovskite green-emitting polycrystalline film, the spacer layer, and the perovskite red-emitting polycrystalline film. Position the UV-curable adhesive between the water-oxygen barrier film and the transparent substrate, ensuring it does not contact the perovskite green-emitting polycrystalline film, the spacer layer, or the perovskite red-emitting polycrystalline film. Irradiate the UV-curable adhesive with a UV lamp for 30 seconds, cool for 1 minute, and then repeat the irradiation process twice more to cure the UV-curable adhesive, thus completing the encapsulation of the perovskite film.

[0109] See Figure 1 This application provides an LCD backlight film, comprising a reflective film 7, a light guide plate 8, a diffusion film 11, and the perovskite light-emitting polycrystalline thin film module prepared above, which are stacked sequentially.

[0110] The perovskite luminescent polycrystalline thin film module includes a transparent substrate 1, a perovskite green luminescent polycrystalline thin film 2, a spacer layer 3, a perovskite red luminescent polycrystalline thin film 4, and a water and oxygen barrier film 5, which are stacked in sequence. The transparent substrate 1 is disposed on the surface of the diffusion film 11.

[0111] Blue LED beads 9 and reflective structure 10 are arranged sequentially on both sides of the light guide plate 8;

[0112] The light-shielding structure 12 is disposed around the reflective film 7 and covers the periphery of the light guide plate 8, the diffusion film 11 and the perovskite light-emitting polycrystalline thin film module.

[0113] Example 2

[0114] See Figure 1This application provides a perovskite luminescent polycrystalline thin film module, including a transparent substrate 1, a perovskite green luminescent polycrystalline thin film 2, a spacer layer 3, a perovskite red luminescent polycrystalline thin film 4, and a water and oxygen barrier film 5 stacked together. An ultraviolet light curable adhesive 6 is bonded to the edge between the transparent substrate 1 and the water and oxygen barrier film 5.

[0115] The preparation method is as follows:

[0116] (1) Cleaning of transparent substrate

[0117] The transparent substrate was cleaned in an ultrasonic cleaner for 15 minutes with acetone, isopropanol and anhydrous ethanol respectively, and then dried with a nitrogen gun to obtain a clean transparent substrate.

[0118] (2) Preparation of green light perovskite precursor solution

[0119] Weigh the corresponding reagents according to the molar ratio of PbBr2:CsBr:PEABr = 1:1:0.4 and dissolve them in 1 ml of a mixed solvent of DMSO:DMF:2ME = 5:4:1 to prepare a precursor solution with a concentration of 0.1 M. Then add 4 mg of crown ether and shake the solution on a shaker for 6 h to obtain the green light perovskite precursor solution.

[0120] (3) Preparation of perovskite green light emitting polycrystalline thin films

[0121] The table temperature of the coating instrument is set to 25℃. The cleaned transparent substrate is vacuum-adsorbed onto the table of the coating instrument. The scalpel is placed at the front end of the transparent substrate. The green perovskite precursor solution is dropped into the gap between the scalpel and the transparent substrate. The green perovskite film is coated on the transparent substrate at a speed of 15 mm / s. The distance between the air knife and the substrate is adjusted to 3 cm, the nitrogen flow rate is 10 L / min, the angle between the air knife and the substrate is 60°, and the air direction is towards the front end of the substrate. The nitrogen is heated to 60℃, and then the air knife is turned on to accelerate the evaporation of the solvent. The transparent substrate is then placed on a 60℃ hot table for annealing for 10 min. The annealed substrate is then placed in an air environment with 60%RH for water and oxygen treatment for 3 min to form a green perovskite luminescent polycrystalline film.

[0122] (4) Preparation of spacer layer precursor solution

[0123] Weigh 10 mg of PVDF and dissolve it in 1 mL of chlorobenzene solution to prepare a 10 mg / mL spacer precursor solution.

[0124] (5) Preparation of spacer layer

[0125] The transparent substrate, after step (3), is vacuum adsorbed onto the table of the scraper. The table temperature of the scraper is set to 45°C. The scraper is placed at the front end of the transparent substrate. The spacer layer precursor solution is dropped into the gap between the scraper and the transparent substrate. The spacer layer is scraped onto the perovskite green light emitting polycrystalline film at a speed of 10 mm / s. The transparent substrate is then placed on a 60°C hot table for annealing for 10 minutes to form the spacer layer.

[0126] (6) Preparation of red light perovskite precursor solution

[0127] Weigh the corresponding reagents according to the molar ratio of CsBr:CsI:PbI2:PEAI = 0.9:0.1:1:0.6 and dissolve them in a mixed solvent of DMF:γ-GBL = 4:1 to prepare a 0.1 M precursor solution. Then add 5 mg of crown ether. Shake the solution for 6 hours to ensure complete dissolution and mixing, to obtain the red light perovskite precursor solution.

[0128] (7) Preparation of perovskite red-luminescent polycrystalline thin films

[0129] The transparent substrate, after step (5), is vacuum adsorbed onto the table of the coating instrument. The table temperature of the coating instrument is set to 60°C. The scalpel is placed at the front end of the transparent substrate. The red light perovskite precursor solution is dropped into the gap between the scalpel and the transparent substrate. The red light perovskite film is coated on the spacer layer at a speed of 30 mm / s. The distance between the air knife and the substrate is adjusted to 5 cm, the nitrogen flow rate is 40 L / min, the angle between the air knife and the substrate is 60°, and the air direction is towards the front end of the substrate. The nitrogen is heated to 80°C, and the air knife is turned on to accelerate the evaporation of the solvent. The transparent substrate is then placed on a 100°C hot table for annealing for 15 min. The annealed substrate is then placed in an air environment with 60%RH for water and oxygen treatment for 3 min to form a perovskite red light emitting polycrystalline film.

[0130] (8) Encapsulation of perovskite thin films

[0131] Apply a small amount of UV-curable adhesive in strips along the four edges of the PVC water-oxygen barrier film, then attach it to the transparent substrate, ensuring the water-oxygen barrier film completely covers the perovskite green-emitting polycrystalline film, the spacer layer, and the perovskite red-emitting polycrystalline film. Position the UV-curable adhesive between the water-oxygen barrier film and the transparent substrate, ensuring it does not contact the perovskite green-emitting polycrystalline film, the spacer layer, or the perovskite red-emitting polycrystalline film. Irradiate the UV-curable adhesive with a UV lamp for 30 seconds, cool for 1 minute, and then repeat the irradiation process twice more to cure the UV-curable adhesive, thus completing the encapsulation of the perovskite film.

[0132] See Figure 1This application provides an LCD backlight film, comprising a reflective film 7, a light guide plate 8, a diffusion film 11, and the perovskite light-emitting polycrystalline thin film module prepared above, which are stacked sequentially.

[0133] The perovskite luminescent polycrystalline thin film module includes a transparent substrate 1, a perovskite green luminescent polycrystalline thin film 2, a spacer layer 3, a perovskite red luminescent polycrystalline thin film 4, and a water and oxygen barrier film 5, which are stacked in sequence. The transparent substrate 1 is disposed on the surface of the diffusion film 11.

[0134] Blue LED beads 9 and reflective structure 10 are arranged sequentially on both sides of the light guide plate 8;

[0135] The light-shielding structure 12 is disposed around the reflective film 7 and covers the periphery of the light guide plate 8, the diffusion film 11 and the perovskite light-emitting polycrystalline thin film module.

[0136] Comparative Example 1

[0137] The preparation method is as follows:

[0138] (1) Cleaning of transparent substrate

[0139] Same as Example 1.

[0140] (2) Preparation of green light perovskite precursor solution

[0141] Same as Example 1;

[0142] (3) Preparation of perovskite green light emitting polycrystalline thin films

[0143] The table temperature of the coating instrument is set to 45℃. The cleaned transparent substrate is vacuum-adsorbed onto the table of the coating instrument. The scalpel is placed at the front end of the transparent substrate. The green perovskite precursor solution is dropped into the gap between the scalpel and the transparent substrate. The green perovskite film is coated on the transparent substrate at a speed of 5 mm / s. The distance between the air knife and the substrate is adjusted to 3 cm, the nitrogen flow rate is 5 L / min, the angle between the air knife and the substrate is 60°, the air direction is towards the front end of the substrate, and room temperature nitrogen is used. The air knife is turned on to accelerate solvent evaporation. The transparent substrate is then placed on a 100℃ hot plate for annealing for 5 min to form a green perovskite polycrystalline film.

[0144] See Figure 2 As shown, Figure 2The white light spectrum of the LCD backlight module prepared in Example 1 is shown, and the accompanying figure illustrates the excellent optical characteristics of the LCD backlight module provided in this application. The spectrum shows three emission peaks: 470 nm represents the excitation light from the blue LED; 535 nm represents the emission peak from the green perovskite film, with a half-width at half-maximum (HWHM) of approximately 20 nm; and 635 nm represents the emission peak from the red perovskite film, with a HWHM of approximately 45 nm. Superimposing these three different colors of light yields white light at 5100K. White backlight sources made with ordinary YAG phosphors typically have a HWHM > 100 nm, while the perovskite backlight source obtained in Example 1 has a narrower HWHM, indicating higher color purity and better color display performance.

[0145] See Figure 3 As shown, Figure 3 The color gamut of the LCD backlight module prepared in Example 1 is shown. As can be seen from the accompanying drawings, the LCD backlight module provided in this application has the advantage of a high color gamut. The chromaticity coordinates (x, y) of the three primary colors (red, green, and blue) are plotted on the CIE 1931 color space chromaticity diagram. A triangle is drawn based on these coordinates; the colors inside the triangle represent the displayable "color gamut." The perovskite backlight obtained in Example 1 can essentially cover the color gamut range of the REC.2020 standard. Typically, a display supporting 95% of the DCI-P3 color gamut is considered a high-end display. The color gamut range of the perovskite backlight obtained in the above example exceeds the DCI-P3 color gamut standard by 40%, which is extremely high in current backlight display performance.

[0146] See Figure 4 As shown, Figure 4 Photographs of the perovskite green light thin films prepared in Example 1 and Comparative Example 1 are shown. The left side shows the perovskite green light thin film prepared in Comparative Example 1. Compared to Example 1, its air knife did not use heated nitrogen, but rather room-temperature nitrogen, and no water or oxygen treatment was performed after annealing. The right side shows the perovskite green light polycrystalline thin film prepared in Example 1. During the preparation process, heated nitrogen was used in the air knife, and after annealing, it was placed in a 30% RH air environment for water and oxygen treatment for 3 minutes. It is clearly visible that the uniformity and brightness of the film on the left are lower than those on the right, indicating that heated nitrogen and water / oxygen treatment help improve the uniformity of the perovskite film, improve the crystal quality of the perovskite, and increase the brightness of the film.

[0147] It should be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0148] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for fabricating a large-area perovskite luminescent polycrystalline thin-film backlight module, characterized in that, Includes the following steps: PbBr2, CsBr and PEABr were dissolved in an organic solvent, and crown ether was added to obtain a green light perovskite precursor solution. CsBr, CsI, PbI2 and PEAI were dissolved in an organic solvent, and crown ether was added to obtain a red light perovskite precursor solution. Preparation of spacer layer precursor solution; The green light perovskite precursor solution was coated onto a transparent substrate, annealed, and treated with water and oxygen to obtain a green light emitting polycrystalline perovskite film. The spacer layer precursor solution was coated onto a perovskite green light emitting polycrystalline thin film and then annealed to obtain the spacer layer. The red light perovskite precursor solution was coated onto the spacer layer, annealed, and treated with water and oxygen to obtain a perovskite red light emitting polycrystalline thin film. A water and oxygen barrier film is encapsulated on the surface of a perovskite red-luminescent polycrystalline thin film.

2. The method for fabricating a large-area perovskite light-emitting polycrystalline thin-film backlight module as described in claim 1, characterized in that, The molar ratio of PbBr2, CsBr and PEABr is 1:1:0.4; And / or, the molar ratio of CsBr, CsI, PbI2 and PEAI is 0.9:0.1:1:0.

6.

3. The method for fabricating a large-area perovskite light-emitting polycrystalline thin-film backlight module as described in claim 1, characterized in that, The organic solvent includes one or more of dimethylformamide, dimethyl sulfoxide, dimercaptoethanol, and γ-butyrolactone.

4. The method for fabricating a large-area perovskite light-emitting polycrystalline thin-film backlight module as described in claim 1, characterized in that, The annealing temperature for green perovskite films is 60-100℃, and the annealing time is 5-20 min. And / or, the annealing temperature of the red light perovskite film is 60-100℃, and the annealing time is 5-20min.

5. The method for fabricating a large-area perovskite light-emitting polycrystalline thin-film backlight module as described in claim 1, characterized in that, During the coating process, air knife drying is used, and the gas used for air knife drying is nitrogen gas. The temperature of the nitrogen gas is 50-80℃ and the flow rate is 5-40L / min.

6. The method for preparing a large-area perovskite light-emitting polycrystalline thin-film backlight module as described in claim 1, characterized in that, The temperature during scraping is 25-60℃, and the scraping speed is 5-30mm / s.

7. The method for fabricating a large-area perovskite light-emitting polycrystalline thin-film backlight module as described in claim 1, characterized in that, The water and oxygen barrier film is made of one or more of polymethyl methacrylate, polycarbonate, polyethylene terephthalate, polypropylene, polyvinyl chloride and polystyrene.

8. The method for preparing a large-area perovskite light-emitting polycrystalline thin-film backlight module as described in claim 1, characterized in that, Encapsulating a water-oxygen barrier film on the surface of a perovskite red-luminescent polycrystalline thin film includes the following steps: UV-curable adhesive is applied to the edge of the water-oxygen barrier film, and then it is attached to the surface of the perovskite red-luminescent polycrystalline film and cured under UV light.

9. A large-area perovskite light-emitting polycrystalline thin-film backlight module, characterized in that, It is prepared by the method described in any one of claims 1-8.

10. An LCD backlight module, characterized in that, It includes a reflective film (7), a light guide plate (8), a diffusion film (11) stacked in sequence, and a large-area perovskite light-emitting polycrystalline thin film backlight module as described in claim 9; The large-area perovskite luminescent polycrystalline thin film backlight module includes a transparent substrate (1), a perovskite green luminescent polycrystalline thin film (2), a spacer layer (3), a perovskite red luminescent polycrystalline thin film (4), and a water and oxygen barrier film (5) stacked sequentially. The transparent substrate (1) is disposed on the surface of the diffusion film (11).

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