Preparation method of high-performance electroluminescent film for flexible display based on ink jet printing

Abstract

The invention provides a preparation method of a high-performance electroluminescent film for flexible display based on ink-jet printing, and relates to the technical field of electroluminescent film ink-jet printing. The preparation method of the high-performance electroluminescent thin film for flexible display based on ink jet printing comprises the following steps of S1, ink material selection and preparation, S2, ink jet equipment preparation, S3, ink jet printing testing, S4, algorithm optimization, S5, printing preparation, S6, ink jet printing, S7, packaging and S8, luminescence performance testing. The polystyrene, the octaethyl porphyrin platinum, the perovskite material and the chloroform are fully mixed to ensure that the ink has good uniformity and stability, and the prepared high-quality ink has efficient charge injection and energy transfer, so that the luminous efficiency is improved, and the service life of the ink is prolonged. An ink droplet overlapping model algorithm can accurately calculate the distribution of ink droplets on a substrate, and a dynamic planning algorithm can ensure that a printing head prints at a correct position.

Description

Technical Field

[0001] The invention relates to the technical field of electroluminescent film inkjet printing, in particular to a method for preparing a high-performance electroluminescent film for flexible display based on inkjet printing. Background Art

[0002] Electroluminescent devices are display devices that use electroluminescent materials to emit light when stimulated. They can be divided into AC and DC types according to the excitation voltage. High-performance electroluminescent films for flexible displays are a key component of flexible display technology, which allows display devices to maintain good display performance when bent or folded. These films are usually made of organic or inorganic luminescent materials and emit light by applying an electric field. High-performance electroluminescent films for flexible displays have the characteristics of high luminous efficiency, wide color gamut, high resolution, fast response time, flexibility, high stability, low power consumption and long life.

[0003] Inkjet printing is a highly efficient special printing method that forms patterns or text by spraying ink directly onto various substrates. It is widely used in many fields due to its flexibility, high resolution, fast printing speed and cost-effectiveness. The preparation of flexible display electroluminescent films also uses inkjet printing technology to directly print luminescent materials on flexible substrates. It can realize patterned, low-cost, large-area luminescent film preparation and is suitable for flexible displays and lighting equipment.

[0004] In the existing inkjet printing process for preparing high-performance electroluminescent films for flexible displays, the configuration of the ink seriously affects the uniformity of the luminescent film. Uneven ink configuration will affect the ink output and the thickness of the luminescent film, and improper overlap of ink droplets will also lead to uneven thickness of the luminescent film and excessive use of ink, which increases costs and may have an impact on the environment. Therefore, those skilled in the art provide a method for preparing high-performance electroluminescent films for flexible displays based on inkjet printing to solve the problems raised in the above background technology. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the shortcomings of the prior art, the present invention provides a method for preparing a high-performance electroluminescent film for a flexible display based on inkjet printing, which solves the problem that the configuration of the ink seriously affects the uniformity of the luminescent film, the uneven ink configuration affects the ink output and the thickness of the luminescent film, and the improper overlap of ink droplets also leads to uneven thickness of the luminescent film and excessive use of ink, which increases costs and may have an impact on the environment.

[0007] (II) Technical solution

[0008] To achieve the above objectives, the present invention is implemented by the following technical scheme: A method for preparing a high-performance electroluminescent film for flexible display based on inkjet printing, comprising the following steps:

[0009] S1. Select and prepare ink materials, and select the energy levels of polystyrene, octaethylporphyrin platinum and perovskite materials by quantum chemical calculation method;

[0010] S1.1. Mixed preparation: 100 g of polystyrene, 100 g of octaethylporphyrin platinum, 100 g of perovskite material and 300 g of chloroform were selected and mixed thoroughly. When the chloroform was heated to 35 degrees, polystyrene was added. After the polystyrene was completely dissolved, when the temperature dropped to 25 degrees, octaethylporphyrin platinum and perovskite material were added to the solvent and stirred thoroughly. While stirring, ultrasonic treatment was used to treat the mixed solution to further disperse the material and reduce the generation of agglomeration. The stirring rate was 500 RPM, and the ultrasonic treatment time was 360 seconds.

[0011] S1.2. Add active agent, add 30g of amino acid derivative to the mixed solution, stir and ultrasonicate the mixed solution again;

[0012] S1.3. Filtration: Filter the mixed solution using a 0.22 micron filter membrane to remove undissolved particles and impurities, conduct a stability test on the prepared ink, and observe whether there is precipitation or stratification after leaving it for a period of time;

[0013] S2. Prepare the inkjet equipment, calibrate the accuracy, inkjet size and inkjet rate of the inkjet printing equipment, the positioning of the flexible substrate, the distance and positioning between the nozzle and the flexible substrate, and ensure the accuracy of inkjet printing;

[0014] S3. Inkjet printing test, by printing calibration patterns on ordinary paper and substrate to evaluate the print quality and obtain the parameters of ink drop size, jetting speed and jetting frequency;

[0015] S3.1. Define the shape and size of ink droplets, circular, elliptical and large. For circular ink droplets, the calculation formula is:

[0016] A drop =πr 2

[0017] Where r is the radius of the ink droplet;

[0018] S3.2. Determine the printing path and ink drop position, and determine the printing path and the position of each ink drop on the substrate according to the requirements of the printing task;

[0019] S3.3. For two adjacent ink droplets, calculate their overlapping area. If the ink droplets are circular, the overlapping area of ​​two circles can be calculated using the following formula:

[0020]

[0021] Where θ is the angle between the line connecting the two circle centers and the horizontal line, which can be calculated using trigonometric numbers;

[0022] S3.4. Add the coverage area and overlap area of ​​all ink droplets to obtain the total coverage area. According to the calculation result, adjust the printing ink drop size, jetting frequency and printing speed to optimize the distribution and overlap of ink droplets, thereby improving the printing quality;

[0023] S4. Optimization algorithm, using particle swarm optimization algorithm to further optimize the ink droplet overlap model. PSO can be used to find the best printing parameters, such as ink droplet size, jetting frequency, printing speed, etc., to achieve the best ink droplet distribution and overlap effect;

[0024] S4.1. In PSO, each particle represents a potential solution in the problem space. The position and velocity of the particle are updated in the search space to find the optimal solution. The position and velocity of the particle are randomly initialized.

[0025] S4.2. Use the ink drop overlap model to evaluate the performance of the printing parameter combination represented by each particle and update the individual best position. If the performance of the current particle is better than its historical best position pbest i , then update pbest i ;

[0026] S4.3. Update the global best position, find the particle with the best performance among all particles, and use its position as the global best position gbest;

[0027] S4.4. Update the particle speed and position, and update the speed and position of each particle according to the above speed update formula;

[0028] S4.5. Termination condition: if the maximum number of iterations is reached or the performance meets the predetermined standard, the iteration is stopped; otherwise, return to step S4.2. Continue iteration;

[0029] S4.6. Output the best solution and the global best position gbest as the optimized printing parameters;

[0030] The particle position update formula is:

[0031]

[0032] in, is the position of ion i at iteration t, is the iteration speed of ion i at t+1;

[0033] The particle velocity update formula is:

[0034]

[0035] Where ω is the inertia weight, c 1 and c 2 is the learning factor, r 1 and r 2 is a random number uniformly distributed in the range [0, 1], pbest i is the individual best position of particle i, and gbest is the global best position.

[0036] S5. Printing preparation, according to the calculated optimal ink drop overlap position, the inkjet head is driven by a high-precision stepper motor or servo motor to ensure its precise movement on the X-axis and Y-axis, and a high-quality linear guide and slider system is used to reduce mechanical vibration and improve positioning accuracy. An encoder is installed on the motor shaft to provide position feedback and realize closed-loop control;

[0037] S6. Inkjet printing, the computer controls the print head to precisely spray ink on the flexible substrate to form the desired pattern. After printing, the substrate is sent to a drying oven or dried naturally at room temperature to remove the solvent in the ink;

[0038] S7. Encapsulation: according to the material properties, ultraviolet light curing is used to ensure that the ink is completely cured and forms a stable light-emitting film, electrode materials are deposited on the light-emitting film to form electrodes of the electroluminescent device, and the device is encapsulated to protect the light-emitting layer from the external environment and extend the service life of the device;

[0039] S8. Luminescence performance test: conduct performance test on the prepared electroluminescent film, including luminescence efficiency, brightness, color coordinates, life span, etc.

[0040] 3. Preferably, step S5 further includes dynamic programming, which avoids repeated calculations by decomposing the problem into smaller sub-problems and storing the solutions of these sub-problems, thereby improving efficiency. The operation steps are as follows:

[0041] A. Generate the movement path of the inkjet head based on the image processing results. This usually involves decomposing the image into a series of straight and curved paths, and using dynamic programming to decompose complex problems into smaller sub-problems to solve them. In path optimization, dynamic programming can be used to find the shortest path;

[0042] B. Clarify the definition and goal of the problem, determine the input and output of the problem, define state variables, represent the sub-problems of the problem, and find the relationship between states, that is, the state transition equation, which describes how to calculate the solution of the current state from one or more smaller states;

[0043] C. Initialize the boundary conditions, determine the solution of the initial state, which is the boundary condition of the problem, and the calculation order, determine the order of calculating the state, usually starting from the smallest sub-problem and gradually calculating to the final state;

[0044] D. Store intermediate results. Use a data structure to store the solution for each state to avoid repeated calculations. Based on the stored intermediate results, build the solution to the final problem. The core of dynamic programming is the state transfer equation, which is:

[0045] f(i)=min j {f(j)+cost(i,j)}

[0046] Where f(i) is the optimal solution for state i, j is all possible previous states to which state i can transfer, and cost(i, j) is the cost of transferring from state j to state i.

[0047] (III) Beneficial effects

[0048] The invention provides a method for preparing a high-performance electroluminescent film for flexible display based on inkjet printing.

[0049] It has the following beneficial effects:

[0050] 1. In the present invention, polystyrene, octaethylporphyrin platinum, perovskite material and chloroform are fully mixed to ensure that the ink has good uniformity and stability, and a high-quality ink is prepared. The prepared ink has efficient charge injection and energy transfer, thereby improving the luminous efficiency, expanding the color range of the luminescent film, and improving the stability.

[0051] 2. In the present invention, the ink droplet overlap model algorithm can accurately calculate the distribution of ink droplets on the substrate, ensure the uniform overlap of ink droplets, thereby improving the uniformity and color consistency of the printed image. The dynamic programming algorithm can ensure that the print head prints at the correct position, improve the accuracy and repeatability of printing, and achieve high-quality and efficient inkjet printing. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Embodiment 1:

[0054] The embodiment of the present invention provides a method for preparing a high-performance electroluminescent film for flexible display based on inkjet printing, comprising the following steps:

[0055] S1. Select and prepare ink materials, and select the energy levels of polystyrene, octaethylporphyrin platinum and perovskite materials through quantum chemical calculation methods to ensure the optimal threshold for charge passage;

[0056] S1.1. Mixed preparation: 100 g of polystyrene, 100 g of octaethylporphyrin platinum, 100 g of perovskite material and 300 g of chloroform were selected and mixed thoroughly. When the chloroform was heated to 35 degrees, polystyrene was added. After the polystyrene was completely dissolved, when the temperature dropped to 25 degrees, octaethylporphyrin platinum and perovskite material were added to the solvent and stirred thoroughly. While stirring, ultrasonic treatment was used to treat the mixed solution to further disperse the material and reduce the generation of agglomeration. The stirring rate was 500 RPM, and the ultrasonic treatment time was 360 seconds.

[0057] S1.2. Add active agent, add 30g of amino acid derivative to the mixed solution, stir and ultrasonicate the mixed solution again;

[0058] S1.3. Filtration: Filter the mixed solution using a 0.22 micron filter membrane to remove undissolved particles and impurities, conduct a stability test on the prepared ink, and observe whether there is precipitation or stratification after leaving it for a period of time;

[0059] S2. Prepare the inkjet equipment, calibrate the accuracy, inkjet size and inkjet rate of the inkjet printing equipment, the positioning of the flexible substrate, the distance and positioning between the nozzle and the flexible substrate, and ensure the accuracy of inkjet printing;

[0060] S3. Inkjet printing test, by printing calibration patterns on ordinary paper and substrate to evaluate the print quality and obtain the parameters of ink drop size, jetting speed and jetting frequency;

[0061] S3.1. Define the shape and size of ink droplets, circular, elliptical and large. For circular ink droplets, the calculation formula is:

[0062] A drop =πr 2

[0063] Where r is the radius of the ink droplet;

[0064] S3.2. Determine the printing path and ink drop position, and determine the printing path and the position of each ink drop on the substrate according to the requirements of the printing task;

[0065] S3.3. For two adjacent ink droplets, calculate their overlapping area. If the ink droplets are circular, the overlapping area of ​​two circles can be calculated using the following formula:

[0066]

[0067] Where θ is the angle between the line connecting the two circle centers and the horizontal line, which can be calculated using trigonometric numbers;

[0068] S3.4. Add the coverage area and overlap area of ​​all ink droplets to obtain the total coverage area. According to the calculation results, adjust the printing ink drop size, jetting frequency and printing speed to optimize the distribution and overlap of ink droplets, thereby improving the printing quality. By fully mixing polystyrene, octaethylporphyrin platinum, perovskite material and chloroform, ensure that the ink has good uniformity and stability, and prepare high-quality ink. The prepared ink has efficient charge injection and energy transfer, thereby improving the luminous efficiency, expanding the color range of the luminescent film, and improving the stability;

[0069] S4. Optimization: The ink droplet overlap model is further optimized using the particle swarm optimization algorithm. PSO can be used to find the best printing parameters, such as ink droplet size, jetting frequency, printing speed, etc., to achieve the best ink droplet distribution and overlap effect;

[0070] S4.1. In PSO, each particle represents a potential solution in the problem space. The position and velocity of the particle are updated in the search space to find the optimal solution. The position and velocity of the particle are randomly initialized.

[0071] S4.2. Use the ink drop overlap model to evaluate the performance of the printing parameter combination represented by each particle and update the individual best position. If the performance of the current particle is better than its historical best position pbest i , then update pbest i ;

[0072] S4.3. Update the global best position, find the particle with the best performance among all particles, and use its position as the global best position gbest;

[0073] S4.4. Update the particle speed and position, and update the speed and position of each particle according to the above speed update formula;

[0074] S4.5. Termination condition: if the maximum number of iterations is reached or the performance meets the predetermined standard, the iteration is stopped; otherwise, return to step S4.2. Continue iteration;

[0075] S4.6. Output the best solution and the global best position gbest as the optimized printing parameters;

[0076] The particle position update formula is:

[0077]

[0078] in, is the position of ion i at iteration t, is the iteration speed of ion i at t+1;

[0079] The particle velocity update formula is:

[0080]

[0081] Where ω is the inertia weight, c 1 and c 2 is the learning factor, r 1 and r 2 is a random number uniformly distributed in the range [0, 1], pbest i is the individual best position of particle i, gbest is the global best position, and the ink droplet overlap model algorithm can accurately calculate the distribution of ink droplets on the substrate to ensure uniform overlap of ink droplets, thereby improving the uniformity and color consistency of the printed image.

[0082] S5. Printing preparation, according to the calculated optimal ink drop overlap position, the inkjet head is driven by a high-precision stepper motor or servo motor to ensure its precise movement on the X-axis and Y-axis, and a high-quality linear guide and slider system is used to reduce mechanical vibration and improve positioning accuracy. An encoder is installed on the motor shaft to provide position feedback and realize closed-loop control;

[0083] S6. Inkjet printing, the computer controls the print head to precisely spray ink on the flexible substrate to form the desired pattern. After printing, the substrate is sent to a drying oven or dried naturally at room temperature to remove the solvent in the ink;

[0084] S7. Encapsulation: according to the material properties, ultraviolet light curing is used to ensure that the ink is completely cured and forms a stable light-emitting film, electrode materials are deposited on the light-emitting film to form electrodes of the electroluminescent device, and the device is encapsulated to protect the light-emitting layer from the external environment and extend the service life of the device;

[0085] S8. Luminescence performance test: conduct performance test on the prepared electroluminescent film, including luminescence efficiency, brightness, color coordinates, life span, etc.

[0086] Step S5 also includes dynamic programming, which improves efficiency by decomposing the problem into smaller sub-problems and storing the solutions of these sub-problems to avoid repeated calculations. The operation steps are as follows:

[0087] A. Generate the movement path of the inkjet head based on the image processing results. This usually involves decomposing the image into a series of straight and curved paths, and using dynamic programming to decompose complex problems into smaller sub-problems to solve them. In path optimization, dynamic programming can be used to find the shortest path;

[0088] B. Clarify the definition and goal of the problem, determine the input and output of the problem, define state variables, represent the sub-problems of the problem, and find the relationship between states, that is, the state transition equation, which describes how to calculate the solution of the current state from one or more smaller states;

[0089] C. Initialize the boundary conditions, determine the solution of the initial state, which is the boundary condition of the problem, and the calculation order, determine the order of calculating the state, usually starting from the smallest sub-problem and gradually calculating to the final state;

[0090] D. Store intermediate results. Use a data structure to store the solution for each state to avoid repeated calculations. Based on the stored intermediate results, build the solution to the final problem. The core of dynamic programming is the state transfer equation, which is:

[0091] f(i)=min j {f(j)+cost(i,j)}

[0092] Where f(i) is the optimal solution for state i, j is all possible previous states to which state i can transfer, and cost(i, j) is the cost of transferring from state j to state i. The dynamic programming algorithm can ensure that the print head prints in the correct position, improve the accuracy and repeatability of printing, and achieve high-quality and efficient inkjet printing.

[0093] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Preparation method of high-performance electroluminescent film for flexible display based on inkjet printing, Features: The following steps are involved: S1. Select and prepare ink materials, and select the energy levels of polystyrene, octaethylporphyrin platinum and perovskite materials by quantum chemical calculation method; S1.

1. Mixed preparation: 100 g of polystyrene, 100 g of octaethylporphyrin platinum, 100 g of perovskite material and 300 g of chloroform were selected and mixed thoroughly. When the chloroform was heated to 35 degrees, polystyrene was added. After the polystyrene was completely dissolved, when the temperature dropped to 25 degrees, octaethylporphyrin platinum and perovskite material were added to the solvent and stirred thoroughly. While stirring, ultrasonic treatment was used to treat the mixed solution to further disperse the material and reduce the generation of agglomeration. The stirring rate was 500 RPM, and the ultrasonic treatment time was 360 seconds. S1.

2. Add active agent, add 30g of amino acid derivative to the mixed solution, stir and ultrasonicate the mixed solution again; S1.

3. Filtration: Filter the mixed solution using a 0.22 micron filter membrane to remove undissolved particles and impurities, conduct a stability test on the prepared ink, and observe whether there is precipitation or stratification after leaving it for a period of time; S2. Prepare the inkjet equipment, calibrate the accuracy, inkjet size and inkjet rate of the inkjet printing equipment, the positioning of the flexible substrate, the distance and positioning between the nozzle and the flexible substrate, and ensure the accuracy of inkjet printing; S3. Inkjet printing test, by printing calibration patterns on ordinary paper and substrate to evaluate the print quality and obtain the parameters of ink drop size, jetting speed and jetting frequency; S3.

1. Define the shape and size of ink droplets, circular, elliptical and large. For circular ink droplets, the calculation formula is: A drop ＝πr 2 Where r is the radius of the ink droplet; S3.

2. Determine the printing path and ink drop position, and determine the printing path and the position of each ink drop on the substrate according to the requirements of the printing task; S3.

3. For two adjacent ink droplets, calculate their overlapping area. If the ink droplets are circular, the overlapping area of ​​two circles can be calculated using the following formula: Where θ is the angle between the line connecting the two circle centers and the horizontal line, which can be calculated using trigonometric numbers; S3.

4. Add the coverage area and overlap area of ​​all ink droplets to obtain the total coverage area. According to the calculation result, adjust the printing ink drop size, jetting frequency and printing speed to optimize the distribution and overlap of ink droplets, thereby improving the printing quality; S4. Optimization: The ink droplet overlap model is further optimized using the particle swarm optimization algorithm. PSO can be used to find the best printing parameters, such as ink droplet size, jetting frequency, printing speed, etc., to achieve the best ink droplet distribution and overlap effect; S4.

1. In PSO, each particle represents a potential solution in the problem space. The position and velocity of the particle are updated in the search space to find the optimal solution. The position and velocity of the particle are randomly initialized. S4.

2. Use the ink drop overlap model to evaluate the performance of the printing parameter combination represented by each particle and update the individual best position. If the performance of the current particle is better than its historical best position pbest i , then update pbest i ; S4.

3. Update the global best position, find the particle with the best performance among all particles, and use its position as the global best position gbest; S4.

4. Update the particle speed and position, and update the speed and position of each particle according to the above speed update formula; S4.

5. Termination condition: if the maximum number of iterations is reached or the performance meets the predetermined standard, the iteration is stopped; otherwise, return to step S4.

2. Continue iteration; S4.

6. Output the best solution and the global best position gbest as the optimized printing parameters; The particle position update formula is: in, is the position of ion i at iteration t, is the iteration speed of ion i at t+1; The particle velocity update formula is: Where ω is the inertia weight, c 1 and c 2 is the learning factor, r 1 and r 2 is a random number uniformly distributed in the range [0, 1], pbest i is the individual best position of particle i, and gbest is the global best position. S5. Printing preparation, according to the calculated optimal ink drop overlap position, the inkjet head is driven by a high-precision stepper motor or servo motor to ensure its precise movement on the X-axis and Y-axis, and a high-quality linear guide and slider system is used to reduce mechanical vibration and improve positioning accuracy. An encoder is installed on the motor shaft to provide position feedback and realize closed-loop control; S6. Inkjet printing, the computer controls the print head to precisely spray ink on the flexible substrate to form the desired pattern. After printing, the substrate is sent to a drying oven or dried naturally at room temperature to remove the solvent in the ink; S7. Encapsulation: according to the material properties, ultraviolet light curing is used to ensure that the ink is completely cured and forms a stable light-emitting film, electrode materials are deposited on the light-emitting film to form electrodes of the electroluminescent device, and the device is encapsulated to protect the light-emitting layer from the external environment and extend the service life of the device; S8. Luminescence performance test: conduct performance test on the prepared electroluminescent film, including luminescence efficiency, brightness, color coordinates, life span, etc.

2. The method for preparing a high-performance electroluminescent film for flexible display based on inkjet printing according to claim 1, Features: The step S5 also includes dynamic programming, which avoids repeated calculations by decomposing the problem into smaller sub-problems and storing the solutions of these sub-problems, thereby improving efficiency. The operation steps are as follows: A. Generate the movement path of the inkjet head based on the image processing results. This usually involves decomposing the image into a series of straight and curved paths, and using dynamic programming to decompose complex problems into smaller sub-problems to solve them. In path optimization, dynamic programming can be used to find the shortest path; B. Clarify the definition and goal of the problem, determine the input and output of the problem, define state variables, represent the sub-problems of the problem, and find the relationship between states, that is, the state transition equation, which describes how to calculate the solution of the current state from one or more smaller states; C. Initialize the boundary conditions, determine the solution of the initial state, which is the boundary condition of the problem, and the calculation order, determine the order of calculating the state, usually starting from the smallest sub-problem and gradually calculating to the final state; D. Store intermediate results. Use a data structure to store the solution for each state to avoid repeated calculations. Based on the stored intermediate results, build the solution to the final problem. The core of dynamic programming is the state transfer equation, which is: f(i)=minj{f(j)+cost(i,j)} Where f(i) is the optimal solution for state i, j is all possible previous states to which state i can transfer, and cost(i, j) is the cost of transferring from state j to state i.

Images