A white light electroluminescent fiber and a method for making the same

Abstract

The application belongs to the technical field of intelligent electronic textiles, and particularly relates to a white light electroluminescent fiber and a preparation method thereof.The preparation method comprises the following steps: compounding doped electroluminescent particles and light conversion luminescent material particles, mixing the compounded particles with a polymer solution to obtain white light electroluminescent active slurry; dipping the white light electroluminescent active slurry on the surface of a conductive fiber, and drying to obtain white light electroluminescent active fiber; designing an external electrode on the surface of the white light electroluminescent active fiber to obtain the white light electroluminescent fiber.The electroluminescent fiber obtained by the application introduces light conversion particles, and by adjusting and controlling the types, particle sizes and coating processes of the light excitation material and the light conversion material, a white light with a high color rendering index, adjustable color temperature and complete and continuous spectrum is finally prepared, and other colors of light can be further obtained from the white light; the prepared white light electroluminescent fiber has good flexibility and light emission stability, and can be widely applied to various wearable electronic devices.

Description

Technical Field

[0001] This invention belongs to the field of intelligent electronic textile technology, specifically relating to a white photoluminescent fiber and its preparation method. Background Technology

[0002] As the demand for flexibility and wearability in electronic devices continues to grow, people are increasingly recognizing that flexible electronic devices with light-emitting and display functions, as terminals for human-computer interaction, directly impact the user experience of electronic devices. To meet this demand, electroluminescent fiber devices have attracted widespread attention, demonstrating enormous commercialization potential due to their high flexibility and ability to be woven into breathable fabrics.

[0003] LEDs and OLEDs are commonly used light-emitting materials in the display and lighting fields. LEDs use inorganic semiconductor materials and are characterized by high lifespan and good stability. OLEDs have a narrow emission spectrum and high brightness, and are widely used in various displays with high color rendering requirements. However, LEDs are inherently rigid, which is incompatible with the modulus of flexible fiber substrates; OLEDs have stringent requirements for film quality and production environment, and are usually produced using vapor deposition processes, making large-scale integration on fiber substrates difficult. Doped zinc sulfide emits light in an alternating electric field and can achieve good light-emitting performance even with low film flatness, making it suitable for the large-scale production of light-emitting fibers. The emission color can be adjusted by doping with different elements. For example, mixing Cu-doped zinc sulfide that emits blue-green light and Mn-doped zinc sulfide that emits orange light can produce white light. However, currently, Mn-doped orange-light-emitting zinc sulfide powder suffers from low brightness and short lifespan, resulting in unsatisfactory stability in the use of Mn-doped white-light-emitting zinc sulfide materials, and an incomplete emission spectrum, leading to a poor color rendering index for white light sources. Therefore, the most common emission colors of commercially available doped zinc sulfide are currently blue and green. Its relatively limited color and lack of white light sources greatly restrict its applications.

[0004] By combining high-efficiency downconversion luminescent materials with zinc sulfide-doped luminescent materials, the former absorbs and converts the luminescence of the latter, thereby broadening the luminescence spectrum of the zinc sulfide-doped luminescent materials. This is expected to yield full-spectrum, high-brightness white electroluminescent fibers, greatly enriching the application scenarios of electroluminescent fibers and enabling their widespread use in various wearable electronic devices. Summary of the Invention

[0005] Given the limitations of the emission spectrum of current zinc sulfide-doped electroluminescent materials, the present invention aims to provide a full-spectrum, high-brightness, and high-stability white electroluminescent fiber and its preparation method, so as to widely meet the requirements of smart electronic textiles and wearable devices.

[0006] This invention involves mixing light-conversion particles and electroluminescent particles to prepare a white electroluminescent active material, which is then added to a polymer matrix with added surfactants. After thorough mechanical stirring, a white electroluminescent active slurry is obtained. This slurry is then coated onto the surface of a bottom electrode fiber to form a coaxial luminescent active fiber. Finally, an external electrode is constructed on the surface of the white electroluminescent layer by winding and / or coating with a conductive coating, resulting in a white electroluminescent fiber. The light-conversion particles are a type of downconversion luminescent material.

[0007] This invention provides a method for preparing white photoluminescent fibers, the specific steps of which are as follows:

[0008] (1) Preparation of white electroluminescent active slurry: Particles of doped electroluminescent material and light-converting luminescent material are added to a polymer matrix solution system containing surfactant and dispersant, and after thorough mechanical stirring, white electroluminescent active slurry is obtained;

[0009] (2) Loading white light luminescent active layer: The white light photoluminescent active slurry prepared in step (1) is loaded onto the surface of the bottom electrode fiber by dip coating to obtain white light photoluminescent active fiber;

[0010] (3) Load the conductive layer onto the surface of the white photoluminescent active fiber prepared in step (2) to obtain the white photoluminescent fiber.

[0011] In step (1), the electroluminescent material particles are zinc sulfide materials (luminescent powder), and the doping elements include, but are not limited to, the following: Mn, Cu, Cl, Al; the particle size of the electroluminescent material particles is 5-30 μm; preferably, the particle size is 10-25 μm.

[0012] In step (1), the light-conversion luminescent material is a downconversion luminescent material, with the excitation wavelength located in the ultraviolet band and the visible light band of 380-520nm, preferably 440-500nm; the emission wavelength is located in the 500-700nm band, preferably 550-650nm. Its emission half-width is 50-130nm, preferably 80-110nm.

[0013] The particle size of the light-converting luminescent material particles is 2-40 μm; the light-converting luminescent particles account for 1-100 wt% of the electroluminescent material (zinc sulfide), preferably 10%-70 wt%.

[0014] The light-converting luminescent material is a rare-earth-doped inorganic material. The electronic energy levels of the doped rare-earth element atoms include 4f and 5d orbitals, enabling it to produce tunable radiation absorption across a wide range from ultraviolet to infrared. When electrons transition from higher energy levels back to lower energy levels via radiation, they release light with longer wavelengths, broadening the spectrum of a single light source. The rare-earth elements include, but are not limited to, one or more of Eu, Er, Y, Ce, La, Yb, Pm, Tb, Tm, and Lu.

[0015] The types of inorganic substances include, but are not limited to, nitrides, fluorides, tungsticomolybdates, silicates, borates, phosphates, aluminates, etc.

[0016] In step (1), the polymer matrix includes, but is not limited to: polyvinyl alcohol, polyurethane, polyacrylate, polyamide, fluororubber, and nitrile rubber.

[0017] The polymer matrix solution system includes, but is not limited to, water, acetone, tetrahydrofuran, N,N-dimethylformamide (DMF), and N-methylpyrrolidone (NMP); the solution system accounts for 30-90 wt% of the white photoluminescent active paste.

[0018] In step (1), a dispersant needs to be added to the polymer matrix in advance. The dispersant includes, but is not limited to, one or more of the following: phosphate dispersants, lignin sulfonate dispersants, polycarboxylic acid dispersants, organosilicon dispersants, silane coupling agents, etc. The amount added is 0.1-5 wt% of the polymer solution, preferably 0.3%-3 wt%.

[0019] In step (1), a surfactant needs to be added to the polymer matrix in advance. The surfactant includes, but is not limited to, one or more of the following: sulfonates, polysiloxanes, carboxymethyl cellulose, polysorbates, and polyoxyethylene fatty alcohol ethers. The amount added is 0.1-3 wt% of the polymer solution, preferably 0.2%-2 wt%.

[0020] Furthermore, when the white photoluminescent active material is added to the polymer matrix, it is added at a uniform rate by mass, and the addition is completed within 2-20 minutes, preferably within 5-15 minutes. The mixture is stirred for 2 hours to obtain a white photoluminescent active slurry; the proportion of the white photoluminescent active material in the white photoluminescent active slurry is 30%-90 wt%, preferably 40-80 wt%.

[0021] In step (1), the light conversion particles need to be pre-mixed with the zinc sulfide luminescent powder in a mixer for a time of 5-60 min, preferably 10-45 min, and a stirring speed of 100-500 rpm, preferably 200-400 rpm.

[0022] In step (2), the loading of the white photoluminescent active paste includes two steps: dip coating and drying.

[0023] The dipping speed is 1-10 m / s, preferably 2-8 m / s;

[0024] The drying temperature is 100-200℃, preferably 120-180℃.

[0025] The thickness of the active layer for white photoluminescence is 10-100 μm, preferably 30-80 μm.

[0026] In step (3), the conductive layer is loaded onto the surface of the white photoluminescent active fiber, including the form of conductive fiber winding and / or conductive coating.

[0027] When the conductive layer is in the form of conductive fiber winding, the types of conductive fibers include, but are not limited to, carbon-based material fibers, conductive polymer chemical fibers, metal-plated chemical fibers, and metal wires. The diameter of the fibers is 20-80 μm, and the winding pitch is 100-1000 μm.

[0028] When the conductive layer is in the form of a conductive coating, the conductive coating includes a transparent silver nanowire conductive film or a transparent conductive polymer film; the thickness of the film is 1-100 μm.

[0029] The electroluminescent fiber obtained by this invention incorporates light conversion particles, combining a highly efficient downconversion luminescent material with a zinc sulfide-doped luminescent material. This allows the former to absorb and convert the luminescence of the latter, broadening the luminescence spectrum of the zinc sulfide-doped luminescent material and obtaining a full-spectrum, high-brightness white electroluminescent fiber. By controlling the type, particle size, and coating process of the photoexcitation and light conversion materials, a white light with a high color rendering index, adjustable color temperature, and a complete and continuous spectrum is finally prepared, from which other colors of light can be further obtained. The prepared white electroluminescent fiber has good flexibility and luminescence stability, and can be widely used in various wearable electronic devices.

[0030] (1) The light conversion material used in this invention has the characteristics of downconversion luminescence, which can absorb ultraviolet-visible light with shorter wavelengths and release visible light with longer wavelengths, and has high quantum efficiency and transmittance.

[0031] (2) By optimizing the spectral matching of light conversion particles and electroluminescent powder, and adjusting the formulation of white electroluminescent active paste, a white electroluminescent fiber with a full spectrum, adjustable color temperature of 4500-12000K, and a color rendering index as high as 93 can be obtained. This fiber has good bending resistance and retains 90% of its original luminous brightness after 5000 bending tests.

[0032] (3) The process of this invention is simple and efficient, with mild conditions. It is a universal method for extending the emission spectrum of doped zinc sulfide. It has good repeatability, low cost, and is suitable for industrial-scale production. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the white photoluminescent fiber structure of the present invention.

[0034] Figure 2 This is the emission spectrum and corresponding CIE color coordinates of the white photoluminescent fiber of the present invention.

[0035] Figure 3 This is a bending resistance test diagram of the white photoluminescent fiber of the present invention.

[0036] In the diagram, the numbers represent: 1 is the bottom electrode fiber, 2 is the doped electroluminescent particle, 3 is the light conversion particle, and 4 is the conductive layer. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0038] In this invention, room temperature refers to an ambient temperature of 10℃ to 30℃.

[0039] All reagents used in the following examples are commercially available, and all equipment is commercially available.

[0040] Schematic diagrams of the white photoluminescent fiber structure in the following embodiments are shown below. Figure 1 As shown.

[0041] Example 1

[0042] Step 1: Prepare white photoluminescent active materials. At room temperature (25°C), 50g of commercially available copper-doped zinc sulfide luminescent powder (particle size 30μm), 30g of sulfide light conversion particles (particle size 20μm), and 5g of aluminate light conversion particles (particle size 15μm) were added to a mixer and pre-mixed for 60min at a stirring speed of 300rpm.

[0043] Step 2: Prepare the white light electroluminescent active slurry. Add 0.1g of polycarboxylic acid dispersant and 0.12g of organosilicon surfactant to 18g of aqueous polyamide emulsion (30% solid content) and stir for 20 minutes at a stirring speed of 400 rpm. Then, slowly add the white light electroluminescent active material obtained in Step 1 at a rate of 6g / min. After all the material has been added, stir for 2 hours at a stirring speed of 600 rpm to obtain a well-dispersed white light electroluminescent active slurry.

[0044] Step 3: Preparation of white photoluminescent active fibers. Turn on the dip-coating device and uniformly coat the white photoluminescent active slurry onto the surface of carbon nanotube conductive fibers (diameter 120μm) at a speed of 10m / s. Dry at 250℃ to a coating thickness of 200μm.

[0045] Step 4: Constructing the external electrode. Turn on the twisting device and evenly wind the copper conductive fiber (20μm in diameter) onto the white photoluminescent active fiber. The winding pitch is 1000μm, and the winding speed is 10m / min. Tension control is used during the winding process to achieve the desired winding effect and avoid twisted structures.

[0046] An alternating electric field with an effective voltage of 110V and a frequency of 2000Hz was applied between the bottom electrode fiber and the outer electrode fiber, resulting in a brightness of 50 cd / m² for the white photoluminescent fiber. 2 The color coordinates are (0.281, 0.310), the color temperature is 8800K, the color rendering index is 93, and the spectrum is comprehensive, providing good comfort and color rendering illumination for the human eye. Test results are as follows... Figure 2 As shown.

[0047] Example 2

[0048] Step 1: Prepare white photoluminescent active materials. At room temperature (25°C), 50g of commercially available manganese-doped zinc sulfide luminescent powder (particle size 30μm), 0.5g of silicate light conversion particles (particle size 15μm), and 0.5g of fluoride light conversion particles (particle size 20μm) were added to a mixer and premixed for 10min at a stirring speed of 300rpm.

[0049] Step 2: Prepare the white light electroluminescent active slurry. Add 0.4g of sodium hexametaphosphate dispersant and 0.5g of sodium alkylbenzene sulfonate surfactant to 30g of polyvinyl alcohol aqueous solution (solid content 15%) and stir for 20min at a stirring speed of 400rpm. Then slowly add the white light electroluminescent active material obtained in Step 1 at a adding rate of 25.5g / min. After all the material has been added, stir for 2h at a stirring speed of 600rpm to obtain a well-dispersed white light electroluminescent active slurry.

[0050] Step 3: Preparation of white photoluminescent active fibers. Turn on the dip-coating device and uniformly coat the white photoluminescent active slurry onto the surface of copper conductive fibers (diameter 140μm) at a speed of 2m / s. Dry at 170℃ to a coating thickness of 40μm.

[0051] Step 4: Constructing the external electrode. Turn on the twisting device and evenly wind the aluminum conductive fiber (80μm in diameter) onto the white photoluminescent active fiber. The winding pitch is 300μm, and the winding speed is 6m / min. Tension control is used during the winding process to achieve the desired winding effect and avoid twisted structures.

[0052] The prepared white photoluminescent fiber exhibits good flexibility and stability; its luminescence brightness remains almost unchanged after 5000 bends, as demonstrated in the test results. Figure 3 As shown.

[0053] Example 3

[0054] Step 1: Prepare white photoluminescent active materials. At room temperature (25°C), 50g of commercially available zinc sulfide luminescent powder (30μm particle size) co-doped with manganese and copper, 15g of silicate light conversion particles (10μm particle size), and 6g of sulfide light conversion particles (8μm particle size) were added to a mixer and pre-mixed for 10min at a stirring speed of 300rpm.

[0055] Step 2: Prepare the white light electroluminescent active slurry. Add 0.14g of silane coupling agent KH570 and 0.2g of polyoxyethylene fatty alcohol ether surfactant to 35g of acetone solution of nitrile rubber (solid content 25%) and stir for 20min at a stirring speed of 400rpm. Then slowly add the white light electroluminescent active material obtained in Step 1 at a rate of 8g / min. After all the material has been added, stir for 2h at a stirring speed of 600rpm to obtain a well-dispersed white light electroluminescent active slurry.

[0056] Step 3: Preparation of white photoluminescent active fibers. Turn on the dip-coating device and uniformly coat the white photoluminescent active slurry onto the surface of the silver-plated conductive fibers (90μm in diameter) at a speed of 5m / s. Dry at 200℃ to a coating thickness of 100μm.

[0057] Step 4: Constructing the external electrode. Turn on the dip-coating device and uniformly coat the white electroluminescent active fiber with the PEDOT:PSS solution at a linear coating speed of 3 m / s. The drying temperature is 160℃. Multiple coatings are required to ensure excellent conductivity of the external electrode.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing white photoluminescent fibers, characterized in that, The specific steps are as follows: (1) Preparation of white electroluminescent active slurry: Add the doped electroluminescent material particles and the light conversion luminescent material particles to the polymer matrix solution system containing surfactant and dispersant, and after thorough mechanical stirring, obtain white electroluminescent active slurry; (2) Loading white light luminescent active layer: The white light photoluminescent active slurry prepared in step (1) is loaded onto the surface of the bottom electrode fiber by dip coating to obtain white light photoluminescent active fiber; (3) Load the conductive layer onto the surface of the white photoluminescent active fiber prepared in step (2) to obtain the white photoluminescent fiber; The electroluminescent material particles are zinc sulfide, and the doping elements are selected from Mn, Cu, Cl, and Al; the particle size of the electroluminescent material particles is 5-30 μm. The light-conversion luminescent material is a downconversion luminescent material, with the excitation main wavelength located in the ultraviolet band and the 380-520 nm visible light band; the emission main wavelength is located in the 500-700 nm band; and its emission half-width is 50-130 nm. The particle size of the light-converting luminescent material particles is 2-40 μm; the light-converting luminescent particles account for 1-100 wt% of the electroluminescent material.

2. The preparation method according to claim 1, characterized in that, In step (1): The light-converting and luminescent material is a rare-earth-doped inorganic material, and the electronic energy levels of the doped rare-earth element atoms include 4f and 5d orbitals; the rare-earth elements are selected from: Eu, Er, Y, Ce, La, Yb, Pm, Tb, Tm, and Lu. The inorganic material is selected from nitrides, fluorides, tungsticolaminates, silicates, borates, phosphates, and aluminates; The polymer matrix is ​​selected from polyvinyl alcohol, polyurethane, polyacrylate, polyamide, fluororubber, and nitrile rubber; The polymer matrix solution system is selected from water, acetone, tetrahydrofuran, N,N-dimethylformamide, and N-methylpyrrolidone; the solution system accounts for 30-90 wt% of the white photoluminescent active slurry.

3. The preparation method according to claim 2, characterized in that, In step (1): A dispersant is added to the polymer matrix in advance. The dispersant is selected from: phosphate dispersants, lignin sulfonate dispersants, polycarboxylic acid dispersants, organosilicon dispersants, and silane coupling agents. The amount of dispersant added is 0.1-5 wt% of the polymer solution. Surfactants are added to the polymer matrix in advance. The surfactants are selected from: sulfonates, polysiloxanes, carboxymethyl cellulose, polysorbates, and polyoxyethylene fatty alcohol ethers. The amount of surfactant added is 0.1-3 wt% of the polymer solution.

4. The preparation method according to claim 3, characterized in that, In step (1), when the white photoluminescent active material is added to the polymer matrix, it is added at a uniform rate by mass and the addition is completed within 2-20 min. After stirring for 2 h, the white photoluminescent active slurry is obtained. The proportion of white photoluminescent active materials in white photoluminescent active slurry is 30%-90 wt%.

5. The preparation method according to claim 4, characterized in that, In step (1), the light conversion particles and the doped zinc sulfide luminescent powder are pre-mixed in a mixer for 5-60 min; the stirring speed is 100-500 rpm.

6. The preparation method according to claim 5, characterized in that, In step (2), the loading of the white photoluminescent active slurry includes dip coating and drying; the dip coating speed is 1-10 m / s, the drying temperature is 100-200℃, and the thickness of the white photoluminescent active layer is 10-100 μm.

7. The preparation method according to claim 6, characterized in that, In step (3), the conductive layer is loaded onto the surface of the white photoluminescent active fiber, which includes the form of conductive fiber winding and conductive coating coating: When the conductive fiber is wound in the form of a conductive fiber, the conductive fiber is selected from carbon-based material fiber, conductive polymer chemical fiber, metal-plated chemical fiber, and metal wire; the diameter of the fiber is 20-80 μm, and the winding pitch is 100-1000 μm; When the conductive coating is applied, the conductive coating is selected from transparent silver nanowire conductive film or transparent conductive polymer film; the thickness of the film is 1-100 μm.

8. A white photoluminescent fiber obtained by the preparation method according to any one of claims 1-7.

9. The application of the white photoluminescent fiber as described in claim 8 in wearable electronic devices.

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