CN111286975A

CN111286975A - Electroluminescent fiber

Info

Publication number: CN111286975A
Application number: CN201811502091.3A
Authority: CN
Inventors: 薛羽利; 吴政樑; 曾胜茂
Original assignee: Taiwan Textile Research Institute
Current assignee: Taiwan Textile Research Institute
Priority date: 2018-12-10
Filing date: 2018-12-10
Publication date: 2020-06-16
Anticipated expiration: 2038-12-10
Also published as: CN111286975B

Abstract

An electroluminescent fiber comprises a linear central electrode, a dielectric layer, an electroluminescent layer and a transparent conductive layer. The dielectric layer covers the linear central electrode. The electroluminescent layer covers the dielectric layer, and the electroluminescent layer comprises 3 to 7 parts by weight of copper-containing zinc sulfide luminescent powder, 0.05 to 0.8 part by weight of metal oxide, 0.1 to 0.7 part by weight of amine alcohol compound, 0.095 to 0.24 part by weight of alkali metal carbonate, and 2.0 to 2.5 parts by weight of PU resin. The metal oxide comprises zinc oxide, titanium dioxide, barium titanate, manganese dioxide, or combinations thereof. The transparent conductive layer covers the electroluminescent layer. The electroluminescent fiber has excellent brightness without additional functional layer, and thus has reduced wire diameter and simplified production process.

Description

Electroluminescent fiber

Technical Field

The present invention relates to an electroluminescent fiber, and more particularly, to an electroluminescent fiber including an electroluminescent layer.

Background

Electroluminescent (EL) light sources have been widely used in various display illumination devices. In the conventional electroluminescent device, high luminance is usually achieved by applying a high voltage. However, there are concerns and dangers associated with using high voltage electroluminescent devices.

In addition, in order to improve the brightness or light extraction rate, the conventional line type electroluminescent device may be further coated with one or more functional layers, such as a strong light-reflecting layer, an inner electron-emitting layer, or an outer electron-emitting layer, outside the central electrode. However, this method complicates the manufacturing process, leads to an increase in cost and wire diameter, and thus reduces the range of use of the line type electroluminescent element. Therefore, a novel electroluminescent element is required to solve the above problems.

Disclosure of Invention

The present disclosure provides an electroluminescent fiber comprising a linear central electrode, a dielectric layer, an electroluminescent layer and a transparent conductive layer. The dielectric layer covers the linear central electrode. The electroluminescent layer covers the dielectric layer, and the electroluminescent layer comprises 3 to 7 parts by weight of copper-containing zinc sulfide luminescent powder, 0.05 to 0.8 part by weight of metal oxide, 0.1 to 0.7 part by weight of amine alcohol compound, 0.095 to 0.24 part by weight of alkali metal carbonate, and 2.0 to 2.5 parts by weight of PU resin. The metal oxide includes zinc oxide (ZnO), titanium dioxide (TiO)₂) Barium titanate (BaTiO)₃) Manganese dioxide (MnO)₂) Or a combination thereof. The transparent conductive layer covers the electroluminescent layer.

In some embodiments, the thickness of the electroluminescent layer is in the range of 25 to 40 microns.

In some embodiments, the electroluminescent fiber has a wire diameter in the range of 300 to 700 microns.

In some embodiments, the dielectric layer has a thickness in a range from 20 microns to 50 microns.

In some embodiments, the electroluminescent fiber further comprises a protective layer covering the transparent conductive layer, wherein the protective layer comprises polyethylene vinyl acetate (EVA) or polyvinyl acetate (PVAC).

In some embodiments, the transparent conductive layer comprises a plurality of silver nanowires, and each silver nanowire has a wire diameter width of 50 nm to 100 nm and a wire length of 5 μm to 50 μm.

In some embodiments, the metal oxide is 0.1 to 0.8 parts by weight zinc oxide (ZnO).

In some embodiments, the metal oxide is 0.05 to 0.3 parts by weight titanium dioxide (TiO)₂)。

In some embodiments, the metal oxide is 0.24 to 0.75 parts by weight barium titanate (BaTiO)₃)。

In some embodiments, the metal oxide is 0.05 to 0.10 parts by weight manganese dioxide (MnO)₂)。

Drawings

Aspects of the present disclosure will become more fully apparent from the following detailed description when read in conjunction with the accompanying drawings. It is noted that, in accordance with standard practice in the industry, the various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a schematic exploded view of an electroluminescent fiber according to an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of an electroluminescent fiber according to an embodiment of the present invention;

FIG. 3 is a schematic exploded view of a thin film electroluminescent device according to an embodiment of the present invention;

fig. 4 to 6 show energy scattering spectra (EDS) of the electroluminescent layer according to the embodiment of the present invention.

Detailed Description

In the following description, for purposes of explanation, numerous implementation details are set forth in order to provide a thorough understanding of the various embodiments of the present invention. It should be understood, however, that these implementation details are not to be interpreted as limiting the invention. That is, in some embodiments of the invention, such implementation details are not necessary. And the size or thickness of elements may be exaggerated and not drawn on scale for clarity. In addition, for simplicity, some conventional structures and elements are shown in the drawings in a simple schematic manner.

Spatially relative terms, such as "below," "beneath," "above," "over," and the like, may be used herein for ease of describing the relative relationship of one element or feature to another element or feature as illustrated in the figures. The true meaning of these spatially relative terms encompasses other orientations. For example, when turned over 180 degrees, the relationship of one element to another may change from "below" to "above" or "above" the relationship. Spatially relative descriptors used herein should be interpreted as such.

Fig. 1 is an exploded perspective view of an electroluminescent fiber 100 according to various embodiments of the present invention. Referring to fig. 1, an electroluminescent fiber 100 includes a linear central electrode 110, a dielectric layer 120, an electroluminescent layer 130, and a transparent conductive layer 140. In various embodiments, wire-like center electrode 110 includes an electrically conductive material, such as, but not limited to, one or more copper wires.

As shown in fig. 1, dielectric layer 120 encapsulates linear center electrode 110. In some embodiments, the dielectric layer 120 comprises a dielectric material. In some embodiments, dielectric layer 120 is formed by drying a dielectric layer formulation including PU resin, water, and barium titanate, wherein the weight ratio of PU resin/water/barium titanate is about 12/4/15, but is not limited thereto. In some embodiments, the density of the dielectric layer is about 4.68 to 5.47 g/mL.

The electroluminescent layer 130 encapsulates the dielectric layer 120. The electroluminescent layer 130 includes 3 to 7 parts by weight of copper-containing zinc sulfide luminescent powder, 0.05 to 0.8 parts by weight of metal oxide, 0.1 to 0.7 parts by weight of an amine alcohol compound, 0.095 to 0.24 parts by weight of an alkali metal carbonate, and 2.0 to 2.5 parts by weight of PU resin. In some embodiments, the copper-containing zinc sulfide phosphor: metal oxide(s): amine alcohol compounds: alkali metal carbonates: the solid content weight ratio of the PU resin is 5: (0.05-0.08): (0.1-0.7): (0.095-0.24): (2.0-2.5). In one embodiment, the weight percentages of the copper-containing zinc sulfide phosphor, the metal oxide, the amine alcohol compound, the alkali metal carbonate, and the PU resin in the electroluminescent layer 130 are 59.6%, 5.9%, 1.2%, and 27.4%, respectively. In some embodiments, the density of electroluminescent layer 130 is, for example, about 2.97-3.38 g/mL.

In some embodiments, electroluminescent layer 130 is formed by drying an electroluminescent paint. In some embodiments, the copper-containing zinc sulfide luminescent powder, the metal oxide and the amine alcohol compound are mixed by shaking, and then the mixture is mixed with the alkali metal carbonate aqueous solution and the PU resin to form the electroluminescent coating.

In some embodiments, the copper-containing zinc sulfide phosphor may be a copper-doped zinc sulfide phosphor, such as ZnS: Cu, and the particle size of the copper-containing zinc sulfide phosphor is, for example, 20 μm to 30 μm.

In some embodiments, the metal oxide comprises zinc oxide (ZnO), titanium dioxide (TiO)₂) Barium titanate (BaTiO)₃) Manganese dioxide (MnO)₂) Or a combination thereof. The conduction band energy of the metal oxide is slightly lower than that of the zinc sulfide luminescent powder, for example, the conduction band of the zinc sulfide luminescent powder is-3.2 eV, the conduction band of the zinc oxide is-4.5 eV, the conduction band of the titanium dioxide is-4.2 eV, the conduction band of the barium titanate is-4.2 eV, and the conduction band of the manganese dioxide is-6.5 eV. Therefore, the metal oxide doped copper-containing zinc sulfide luminescent powder can provide a stepped charge injection mode, reduce the energy gap and simultaneously improve the capacitance value of the electroluminescent layer 130, thereby improving the luminous intensity of the electroluminescent layer 130. The metal oxide can be directly mixed with the copper-containing zinc sulfide luminescent powder without annealing, sintering and other processes, thereby simplifying the manufacturing process and saving the cost,and simultaneously, the brightness is improved. Fig. 4 to 6 show energy scattering spectra (EDS) of an electroluminescent layer according to an embodiment of the present invention, wherein fig. 4 is an electroluminescent layer doped with barium titanate, fig. 5 is an electroluminescent layer doped with manganese dioxide, and fig. 6 is an electroluminescent layer doped with titanium dioxide. As can be seen from fig. 4 to 6, the metal oxide is directly doped in the electroluminescent layer without high temperature processes such as annealing or sintering, so that the metal oxide in the electroluminescent layer can maintain its original oxidation state.

In some embodiments, the metal oxide is 0.1 to 0.8 parts by weight zinc oxide (ZnO), for example 0.1, 0.5, or 0.8 parts by weight. In some embodiments, the metal oxide is 0.05 to 0.3 parts by weight titanium dioxide (TiO)₂) For example 0.05, 0.1, 0.15, 0.2 or 0.3 parts by weight. In some embodiments, the metal oxide is 0.24 to 0.75 parts by weight barium titanate (BaTiO)₃) For example 0.24, 0.57 or 0.75 parts by weight. In some embodiments, the metal oxide is 0.05 to 0.10 parts by weight manganese dioxide (MnO)₂) E.g., 0.05, 0.08 or 0.1 parts by weight, wherein the manganese dioxide may be α -MnO₂Or β -MnO₂。

In some embodiments, the amine alcohol compound may include ethylene glycol or diethanolamine. The amine alcohol compound can be used as a surface modifier to help the copper-containing zinc sulfide luminescent powder to be dispersed in the PU resin. The amine alcohol compound can also form dipole (interfacial dipole) on the surface of the copper-containing zinc sulfide luminescent powder, thereby reducing the barrier of injecting charges from PU resin into the copper-containing zinc sulfide luminescent powder.

In some embodiments, the alkali metal carbonate may comprise potassium carbonate or cesium carbonate. The alkali carbonate can polarize the PU resin, so as to promote the generation of ionic space electric field (ionic space charge field), and increase the capacitance of the electroluminescent layer 130, thereby increasing the luminous intensity.

Please continue to refer to fig. 1. The transparent conductive layer 140 encapsulates the electroluminescent layer 130. In some embodiments, the transparent conductive layer 140 includes a plurality of silver nanowires, each silver nanowire has a wire diameter width of 50 nm to 100 nm, such as 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 nm, and a wire length of 5 microns to 50 microns, such as 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 microns.

In some embodiments, electroluminescent fiber 100 further comprises a protective layer 150 that encapsulates transparent conductive layer 140. In some embodiments, the protective layer 150 includes polyethylene vinyl acetate (EVA) or polyvinyl acetate (PVAC), but is not limited thereto. The protection layer 150 may be a transparent protection layer to protect the transparent conductive layer 140 and prevent the transparent conductive layer 140 from being damaged during the use process. However, the present invention is not limited thereto, and the protective layer 150 may be omitted in other embodiments. In some embodiments, the electroluminescent fiber 100 is flexible. The flexible properties of the electroluminescent fiber 100 can be adjusted by adding a cross-linking agent to the resin material. The flexible electroluminescent fiber 100 can be applied to various types of electroluminescent objects, such as wires, cloth, backlight panels of advertisement boxes, etc.

In some embodiments, the method for manufacturing the electroluminescent fiber 100 may include sequentially forming the dielectric layer 120, the electroluminescent layer 130 and the transparent conductive layer 140 by wet or dry coating, and disposing the above-mentioned layers on the linear central electrode 110 by wire winding.

Fig. 2 is a schematic cross-sectional view of an electroluminescent fiber 100 according to various embodiments of the present invention. Please refer to fig. 2. In various embodiments, electroluminescent fiber 100 has a wire diameter D1 in a range from 300 microns to 700 microns, such as 300, 350, 400, 450, 500, 550, 600, 650, or 700 microns. In some embodiments, the thickness T1 of the dielectric layer 120 is in a range from 20 microns to 50 microns, such as 20, 25, 30, 35, 40, 45, or 50 microns. In some embodiments, the thickness T2 of electroluminescent layer 130 is in the range of 25 microns to 40 microns, such as 25, 30, 35, or 40 microns.

Fig. 3 is an exploded perspective view of a thin film electroluminescent device 200 according to another embodiment of the present invention. Referring to fig. 3, the thin film electroluminescent device 200 includes a conductive layer 210, a dielectric layer 220, an electroluminescent layer 230 and a transparent conductive layer 240.

In some embodiments, the conductive layer 210 may be a silver glue conductive layer, and the thickness of the conductive layer 210 may be in a range of 20 microns to 30 microns, such as 20, 25, or 30 microns.

A dielectric layer 220 is located between and separates the conductive layer 210 and the electroluminescent layer 230. In some embodiments, the materials of the dielectric layer 220 and the electroluminescent layer 230 may be the same as or similar to the dielectric layer 120 and the electroluminescent layer 130 of the electroluminescent fiber 100, respectively, and thus are not described again. In some embodiments, the thickness of the dielectric layer 220 is in a range from 35 microns to 45 microns, such as 35, 40, or 45 microns. In some embodiments, the thickness of the electroluminescent layer 230 is in the range of 25 microns to 50 microns, such as 25, 30, 35, 40, 45, or 50 microns.

In some embodiments, the material of the transparent conductive layer 240 can be the same as or similar to the transparent conductive layer 140 of the electroluminescent fiber 100, including, but not limited to, Indium Tin Oxide (ITO) conductive glass, for example. In some embodiments, the transparent conductive layer 240 is, for example, Indium Tin Oxide (ITO) conductive glass having a transmittance of about 89%.

As shown in fig. 3, the conductive layer 210 and the transparent conductive layer 240 can be used as electrodes in the thin film electroluminescent device 200 and are connected to an external power source (not shown) through

wires

250 and 260, respectively.

In some embodiments, the electroluminescent layer 230, the dielectric layer 220 and the conductive layer 210 are sequentially disposed on the transparent conductive layer 240 by wet bar coating to form the thin film electroluminescent device 200.

The following examples are presented to illustrate specific aspects of the present invention and to enable those of ordinary skill in the art to practice the invention. However, the following examples should not be construed as limiting the invention.

Experimental example 1: brightness testing of electroluminescent fibers

In this experimental example, please refer to the manufacturing method of the electroluminescent fiber 100 in the first embodiment and the first comparative example, which will not be described again. The difference between the first embodiment and the first comparative embodiment is that the two different electroluminescent layers have different solid contents of the components in the electroluminescent layer, as shown in the first table below. In the experimental example, the linear center electrode is a copper metal wire with a wire diameter of 160 micrometers and a length of 10 centimeters; the dielectric layer is formed by drying a formula consisting of PU resin, water and barium titanate with the weight ratio of 12/4/15, and the thickness and the density of the dielectric layer are 40 micrometers and 4.68g/mL respectively; and the transparent conductive layer is formed by drying a formula consisting of PU resin/silver colloid with the weight ratio of 2/3, and the thickness and the density of the transparent conductive layer are 23 microns and 6.69 g/mL.

The results of the brightness tests on the electroluminescent fibers of the first example and the first comparative example were carried out with an AC current of 11kHz at 160 volts, using an absolute brightness meter (model BM-7A, from Topcon Co.). The difference between the first embodiment and the first comparative embodiment is: the electroluminescent layer of example one comprises zinc oxide. As can be seen from table one, the brightness of the electroluminescent fiber can be increased by about 34.9% in the embodiment by using the electroluminescent layer of zinc oxide blended with the copper-containing zinc sulfide luminescent powder, compared to the comparative example one.

Watch 1

Experimental example 2: comparison of the zinc oxide doping concentration with the luminance of a thin film electroluminescent device

In this experimental example, please refer to the manufacturing method of the thin film electroluminescent device 200 in the second and third comparative examples and the second to fourth examples, which will not be described again.

In this experimental example, the electroluminescent layers of the second and third comparative examples and the second to fourth examples were doped with zinc oxide in different weight parts, and the solid contents of the respective components in the electroluminescent layers are shown in the following table two. In addition, in this experimental example, an ITO glass substrate having a surface resistance of 7 Ω/sq was used as the transparent conductive layer, and the size of the thin film electroluminescent devices of comparative example two and example two was 1.5cm × 2.5cm, and the size of the thin film electroluminescent devices of comparative example three, and example four was 0.7cm × 2.0 cm. A formulation of PU resin/water/barium titanate in a weight ratio of 4/4/15 was used to dry to form a dielectric layer having a thickness of 40 microns, and a silver paste layer having a thickness of 23 microns was used.

The thin film electroluminescent devices of comparative examples two and three and examples two to four were tested for brightness using a luminance meter (model: TES-137, available from Shi electronics, Inc.) with an AC current of 160V and 11kHz, and brightness changes were compared, and the results are shown in Table two below.

Watch two

As can be seen from the table two, compared to the comparative example two, the example two can increase the brightness by about 8.4% by using the zinc oxide blended with the copper-containing zinc sulfide luminescent powder. Compared with the third comparative example, the third and fourth examples can increase the brightness by about 47.5% and 8.3% respectively by using the zinc oxide mixed with the copper-containing zinc sulfide luminescent powder.

Experimental example 3: comparison of the concentration of the doped titanium dioxide with the luminance of the thin-film electroluminescent device

In this experimental example, the manufacturing method, material and luminance testing method of the thin film electroluminescent device of the fourth comparative example and the fifth to tenth examples are similar to those of experimental example 2, and only differences from experimental example 2 will be described below.

In this experimental example, the electroluminescent layers of the fourth comparative example and the fifth to tenth examples were doped with different weight parts of titanium dioxide, and the solid contents of the respective components in the electroluminescent layers are shown in the following table three. In this experimental example, the size of the thin film electroluminescent device was 0.7cm × 2.0 cm. The dielectric layer was formed to a thickness of 40 microns using a PU resin/water/barium titanate formulation with a weight ratio of 12/4/15 for drying.

Watch III

As can be seen from table three, the brightness of the luminescent powders of examples five to nine, which are obtained by blending copper-containing zinc sulfide with titanium dioxide, can be increased by about 24.4%, 30.8%, 22.3%, 19.1%, and 13.8%, respectively, compared to the fourth comparative example. Whereas the use of titanium dioxide in too high a concentration in example ten resulted in a 23.4% reduction in brightness.

Experimental example 4: comparison of the concentration of the doped barium titanate with the luminance of the thin-film electroluminescent device

In this experimental example, the manufacturing method, material and luminance testing method of the thin film electroluminescent devices of the eleventh to fourteenth embodiments are similar to those of the experimental example 3, except that the electroluminescent layers of the eleventh to fourteenth embodiments are respectively doped with different parts by weight of barium titanate, and the solid contents of the respective components in the electroluminescent layers are shown in the following table four.

Watch four

As can be seen from table four, the luminance of the light-emitting powders of examples eleven to thirteen, which are doped with copper-containing zinc sulfide by using barium titanate, can be increased by about 22.3%, 29.8%, and 19.9%, respectively, as compared with the fourth comparative example. While example fourteen uses barium titanate of too high a concentration resulted in a 4.3% decrease in brightness.

Experimental example 5: comparison of the concentration of the doped manganese dioxide with the luminance of the thin film electroluminescent device

In this experimental example, the manufacturing method, material and luminance testing method of the thin film electroluminescent devices of the fifteenth to seventeenth embodiments are similar to those of the experimental example 3, except that the electroluminescent layers of the fifteenth to seventeenth embodiments are respectively doped with different weight parts of manganese dioxide, and the solid contents of the respective components in the electroluminescent layers are shown in the following table five.

Watch five

As can be seen from table five, the brightness of the luminescent materials of the working examples fifteen to sixteen can be increased by about 17.0% and 13.8% respectively by using manganese dioxide doped with copper-containing zinc sulfide. Whereas example seventeen using barium titanate at too high a concentration resulted in a 27.7% decrease in brightness.

Experimental example 6: effect of aminoalcohol-based Compound and alkali carbonate-based Compound on Brightness

In this experimental example, please refer to the third comparative example for the methods for manufacturing the thin film electroluminescent devices, materials and methods for testing brightness in the eighteenth and nineteenth examples. Eighteen, nineteen examples are different from the third comparative example in that the electroluminescent layer of eighteen examples is doped with 0.5 parts by weight of zinc oxide and diethanolamine is used instead of ethylene glycol; the electroluminescent layer of the nineteenth example was doped with 0.5 parts by weight of zinc oxide and cesium carbonate was used instead of potassium carbonate, and the solid contents of the respective components in the electroluminescent layer are shown in table six below.

Watch six

From table six, in the eighteen examples, the brightness is improved by 38.3% under the condition of doping zinc oxide and replacing ethylene glycol with diethanolamine. Example nineteen the brightness was increased by 16.3% under the conditions of doping zinc oxide and substituting cesium carbonate for potassium carbonate.

In summary, the present disclosure provides an electroluminescent fiber. By doping metal oxide, such as zinc oxide, titanium dioxide, barium titanate or manganese dioxide, in the electroluminescent layer of the electroluminescent fiber, the brightness of the electroluminescent fiber can be improved without configuring an additional functional layer, so that the wire diameter of the electroluminescent fiber can be reduced, and the manufacturing process can be simplified. In addition, the electroluminescent fiber of the present disclosure has high brightness without applying a high voltage, and thus can be applied to various types of electroluminescent articles.

Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. An electroluminescent fiber, comprising:

a linear center electrode;

a dielectric layer covering the linear central electrode;

an electroluminescent layer that wraps the dielectric layer, and the electroluminescent layer includes:

3 to 7 parts by weight of a copper-containing zinc sulfide luminescent powder;

0.05 to 0.8 parts by weight of a metal oxide comprising zinc oxide (ZnO), titanium dioxide (TiO)₂) Barium titanate (BaTiO)₃) Manganese dioxide (MnO)₂) Or a combination thereof;

0.1 to 0.7 parts by weight of an aminoalcohol-based compound;

0.095 to 0.24 parts by weight of an alkali metal carbonate; and

2.0 to 2.5 parts by weight of a PU resin; and

and the transparent conducting layer coats the electroluminescent layer.

2. The electroluminescent fiber of claim 1, wherein the electroluminescent layer has a thickness in the range of 25 to 40 microns.

3. The electroluminescent fiber of claim 1, wherein the electroluminescent fiber has a wire diameter in the range of 300 to 700 microns.

4. The electroluminescent fiber of claim 1, wherein the dielectric layer has a thickness in the range of 20 to 50 microns.

5. The electroluminescent fiber of claim 1, further comprising a protective layer covering the transparent conductive layer, wherein the protective layer comprises polyethylene vinyl acetate (EVA) or polyvinyl acetate (PVAC).

6. The electroluminescent fiber according to claim 1, wherein the transparent conductive layer comprises a plurality of nano silver wires, and each of the nano silver wires has a wire diameter width of 50 nm to 100 nm and a wire length of 5 μm to 50 μm.

7. The electroluminescent fiber of claim 1, wherein the metal oxide is zinc oxide (ZnO) in an amount of 0.1 to 0.8 parts by weight.

8. The electroluminescent fiber of claim 1, wherein the metal oxide is 0.05 to 0.3 parts by weight of titanium dioxide (TiO)₂)。

9. The electroluminescent fiber of claim 1, wherein the metal oxide is 0.24 to 0.75 parts by weight of barium titanate (BaTiO)₃)。

10. The electroluminescent fiber of claim 1, wherein the metal oxide is 0.05 to 0.10 parts by weight manganese dioxide (MnO)₂)。