A white light ac electroluminescent device and a method for making the same

Abstract

This invention discloses a white-light alternating current electroluminescent device, comprising a transparent substrate, a transparent bottom electrode, a light-emitting layer, a dielectric layer, and an opaque top electrode arranged in sequence. The light-emitting layer comprises an electroluminescent material, with one side of the transparent substrate serving as the light-emitting surface. It also includes a dual-color conversion layer located on one side of the light-emitting surface of the light-emitting layer, comprising a first photoluminescent material region and a second photoluminescent material region of different colors. The light-emitting layer emits a first color of light under the drive of an alternating current electric field, and the dual-color conversion layer is excited by the first color of light to generate a second and a third color of light, which are then emitted together to form white light. This invention also discloses its fabrication method. The ACEL device of this invention can also achieve low-kJ / ... B Its comprehensive performance, including high color rendering index, provides an effective technical solution for developing safe, healthy, and high-quality flexible lighting and display products.

Description

Technical Field

[0001] This invention belongs to the field of alternating current electroluminescence technology, specifically relating to a white light alternating current electroluminescent device and its preparation method. Background Technology

[0002] Alternating current electroluminescent (ACEL) devices have attracted much attention in the fields of flexible lighting, display and interactive interface due to their unique performance, and are a potential candidate for next-generation wearable lighting devices. ACEL devices mainly have two typical structures: (1) Symmetric structure: transparent electrode layer / dielectric layer / emitting layer / dielectric layer / electrode layer; (2) Asymmetric structure: transparent electrode layer / emitting layer / dielectric layer / electrode layer.

[0003] Existing research has largely focused on optimizing the driving methods, structural design, fabrication processes, and materials (including electrode and luminescent materials) of ACEL devices. However, it has generally overlooked the potential harm of blue light radiation to the human eye, especially to sensitive individuals with weakened immune systems. Therefore, effectively mitigating its potential non-visual biological effects while meeting visual function requirements has become a crucial issue that urgently needs to be addressed.

[0004] When assessing the potential harm of blue light to the human body, the "Blue Light Hazard Efficacy" (BLHER) or "Blue Light Hazard Factor" (K) is commonly used. B As an evaluation index of non-visual biological effects, lower BLHER and K values... B The value indicates that the blue light radiation from the device poses a relatively low potential risk to the human eye.

[0005] Among them, blue light radiation hazard factor K B The calculation formula is:

[0006]

[0007] in Spectral power distribution representing the light source ( ); = This represents the maximum spectral light efficiency value for photopic vision. Represents the photoluminescence efficiency function; This is a weighting function for the blue light hazard in the visible spectrum.

[0008] Currently, the main technical approaches to reducing the impact of blue light fall into two categories: one is optimization at the light source end, such as reducing harmful blue light components at the source by improving phosphor formulations; the other is processing at the application end, such as using external filters to absorb or block some blue light. However, traditional phosphor formulations have limited room for adjustment, making it difficult to simultaneously achieve a high color rendering index and high brightness. Adding external filters introduces additional optical interfaces, leading to a loss of luminous efficiency and making it difficult to meet the development trend of flexible and thin ACEL devices. These problems limit the further development of ACEL devices. Summary of the Invention

[0009] This invention addresses the shortcomings of existing technologies by providing a white light alternating current electroluminescent device and its fabrication method.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows:

[0011] A white light alternating current electroluminescent device includes a transparent substrate, a transparent bottom electrode, a light-emitting layer, a dielectric layer, and an opaque top electrode arranged in sequence. The light-emitting layer includes an electroluminescent material, and one side of the transparent substrate is the light-emitting surface. It also includes a dual-color conversion layer located on the light-emitting surface side of the light-emitting layer, comprising a first photoluminescent material region and a second photoluminescent material region of different colors. The light-emitting layer emits a first color of light under the drive of an alternating current electric field, and the dual-color conversion layer is excited by the first color of light to generate a second color of light and a third color of light, which are then emitted together to form white light.

[0012] Optionally, the dual-color conversion layer is disposed between the transparent bottom electrode and the light-emitting layer.

[0013] Furthermore, the white light alternating current electroluminescent device structure includes: a transparent substrate, a transparent bottom electrode covered on the transparent substrate, a dual-color conversion layer covered on the bottom electrode, a light-emitting layer covered on the dual-color conversion layer, a dielectric layer covered on the light-emitting layer, and an opaque top electrode covered on the dielectric layer.

[0014] Optionally, the dual-color conversion layer is disposed on the side of the transparent substrate opposite to the transparent bottom electrode.

[0015] Furthermore, the white light alternating current electroluminescent device structure includes: a transparent substrate, a transparent bottom electrode covered on the transparent substrate, a dual-color conversion layer covered on the other side of the transparent substrate (i.e., the side without the bottom electrode), a light-emitting layer covered on the transparent bottom electrode, a dielectric layer covered on the light-emitting layer, and an opaque top electrode covered on the dielectric layer.

[0016] Optionally, the photoluminescent materials used in the first and second photoluminescent material regions of the dual-color conversion layer are selected from excitation spectral materials with medium or higher excitation wavelengths. The excitation spectral materials are classified using the full width at half maximum (FWHM) as the core criterion. The luminescent material may exhibit multiple peaks or shoulder peaks due to the coexistence of multiple emission centers. Medium-width excitation spectral fluorescent materials have an FWHM between 50 and 100 nm and a relatively broad peak shape; wide excitation spectral fluorescent materials have an FWHM ≥ 100 nm, a broad peak shape, and no obvious shoulder peaks. A larger FWHM in the excitation spectrum of a luminescent material indicates that its emission spectrum is more easily affected by the excitation wavelength. The peak position of excitation spectral materials with medium or higher excitation wavelengths is more likely to shift with changes in excitation wavelength, allowing for variations in the emission wavelength of the electroluminescent material.

[0017] Optionally, the transparent substrate includes at least one of polyethylene terephthalate, colorless polyimide (PI), silicon wafer, glass, etc.

[0018] Optionally, the transparent bottom electrode includes at least one of indium tin oxide (ITO), metal nanowires, graphene, carbon nanotubes, etc.

[0019] Optionally, the dielectric layer is composed of a mixture of two or more materials, characterized by containing inorganic particles and an organic polymer; the inorganic particles are at least one of barium titanate or titanium dioxide; the organic polymer is at least one of polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF), polydimethylsiloxane (PDMS), Ecoflex, etc.

[0020] Optionally, the opaque top electrode includes at least one of a silver layer, a carbon layer, ITO, aluminum, etc.

[0021] Optionally, the first color light is blue light, the second color light is red light, and the third color light is green light. Driven by an alternating electric field, the emitted blue light is converted into red and green light by the first photoluminescent material region where the red photoluminescent fluorescent material is located and the second photoluminescent material region where the green photoluminescent fluorescent material is located. The red and green light are mixed and emitted together to form white light. There is no sharp blue light peak in the spectrum, especially in the wavelength range (435~440nm) which has the greatest potential harm to the retina.

[0022] Optionally, the area ratio of the first photoluminescent material region and the second photoluminescent material region is (3:6) to (9:6).

[0023] Optionally, the emission spectrum can be adjusted by regulating the area ratio of the first photoluminescent material region and the second photoluminescent material region covering the light-emitting layer, and K can be adjusted by regulating the driving voltage or frequency of the alternating electric field. B value.

[0024] Optionally, the electroluminescent material is ZnS:Cu; the driving voltage of the alternating electric field is 50V ~ 300V, and the frequency is 50Hz ~ 400Hz.

[0025] The emission spectrum of ZnS:Cu electroluminescent phosphors is affected by the driving voltage and frequency, causing changes in the emission spectrum of the green luminescent material region. However, this can be reconciled by adjusting the area ratio of the dual-color conversion layer. The emission spectrum of the red luminescent material region is almost unaffected by changes in the excitation spectrum. Since the total area of ​​the luminescent layer is constant, as the relative coverage area of ​​the red luminescent material region increases, the red component in the device's emission spectrum increases, and the device's display index also increases accordingly, but not indefinitely.

[0026] K of white ACEL devices B The value is mainly related to the blue light peak value. We need to be wary of short-wavelength blue light, which has high energy and strong penetrating power, and can reach the retina directly. The 435-440nm band is the most dangerous and poses the greatest potential harm to the retina. The harmfulness of longer wavelength, more bluish blue light has been significantly reduced. White ACEL devices obtained by emitting both red and green light have low K0. B Value. Since the sharp blue light peak accounts for a small proportion of the emission spectrum of white ACEL devices, the voltage affects K. B The value has a relatively small impact; however, increasing the frequency causes a blue shift in the emission wavelength of ZnS:Cu, affecting K. B The effect of K is more pronounced; the smaller the frequency, the more significant the effect. B The smaller the value, the better.

[0027] A method for fabricating the aforementioned white light alternating current electroluminescent device includes forming a transparent bottom electrode, a light-emitting layer, a dielectric layer, and an opaque top electrode sequentially on one side of a transparent substrate; it also includes forming a dual-color conversion layer, wherein the dual-color conversion layer is formed before the light-emitting layer or on the other side of the transparent substrate according to the stacking order.

[0028] Optionally, the dual-color conversion layer is formed on the surface of the transparent substrate or the surface of the transparent bottom electrode by a printing process.

[0029] In one embodiment, the fabrication method of the white light ACEL device includes the following steps:

[0030] A transparent bottom electrode is formed on a transparent substrate;

[0031] Electroluminescent fluorescent material is printed on the transparent bottom electrode, dried and cured to form a light-emitting layer;

[0032] A high-dielectric material is printed on the light-emitting layer to form a dielectric layer;

[0033] An opaque top electrode is formed on the dielectric layer;

[0034] Two photoluminescent fluorescent materials are printed on the other side of the transparent substrate (i.e. the side without the bottom electrode). The area ratio of the two photoluminescent fluorescent materials covering the light-emitting layer can be (3:6) to (9:6). After drying and curing, a dual-color conversion layer is formed, which is then encapsulated to complete the fabrication of the white light ACEL device.

[0035] In another embodiment, the method for fabricating the white light ACEL device includes the following steps:

[0036] A transparent bottom electrode is formed on a transparent substrate;

[0037] Two photoluminescent fluorescent materials are printed on a transparent bottom electrode. The area ratio of the two photoluminescent fluorescent materials can be (3:6) to (9:6). The material is then dried and cured to form a dual-color conversion layer.

[0038] Electroluminescent fluorescent material is printed on the dual-color conversion layer, dried and cured to form a light-emitting layer;

[0039] A high-dielectric material is printed on the light-emitting layer to form a dielectric layer;

[0040] An opaque top electrode is formed on the dielectric layer; the device is then packaged to complete the fabrication of the white light ACEL device.

[0041] The beneficial effects of this invention are as follows:

[0042] This invention forms a dual-color conversion layer by uniformly coating two different colored photoluminescent fluorescent materials in an area ratio onto the emitting layer of an ACEL. The electroluminescent fluorescent material in this emitting layer emits a first color light under the drive of an alternating electric field. This first color light is converted into a second and a third color light by the photoluminescent material in the dual-color conversion layer. The second and third color lights are emitted together to form white light. By adjusting the area ratio of the dual-color conversion layer to adjust the white light emission spectrum, a white ACEL device with a high color rendering index can be obtained.

[0043] When the first color light is blue light, the K of the white light ACEL device... BThe value is mainly related to the blue light peak. The white light spectrum, composed of two colors, does not contain a sharp blue light peak, especially in the band (435-440 nm) which poses the greatest potential harm to the retina. By adjusting the driving voltage and frequency, a low K value can be obtained. B The white light ACEL device meets the visual function requirements while effectively avoiding the damage caused by non-visual biological effects of blue light radiation.

[0044] The fabrication process is simple and easy to operate, and it can be fabricated on flexible substrates to realize flexible and stretchable light-emitting devices.

[0045] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the structure of the white light ACEL device in Example 1.

[0047] Figure 2 The fitted emission spectra of R0G1 and R1G0 in Example 1 are shown in the inset (the excitation spectrum of the photoluminescent material at 450 nm is shown in the inset).

[0048] Figure 3 The emission spectrum of RxGy in Example 1 is shown.

[0049] Figure 4 This is a schematic diagram of the spectral color coordinates of RxGy in Example 1 (the inset is a schematic diagram of the CIE coordinates of R6G6 changing with frequency).

[0050] Figure 5 This is a schematic diagram of the CRI of RxGy in Example 1.

[0051] Figure 6 K of RxGy in Example 1 B Value diagram.

[0052] Figure 7 This is a schematic diagram of the structure of the white light ACEL device in Example 2. Detailed Implementation

[0053] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments. The accompanying drawings are merely illustrative to facilitate a better understanding of the invention, and their specific proportions can be adjusted according to design requirements. The "upper" and "lower" relationships of relative elements and the definitions of "front" and "back" in the graphics described herein should be understood by those skilled in the art to refer to the relative positions of the components; therefore, they can all be flipped to present the same component, and all of this should fall within the scope disclosed in this specification.

[0054] In this invention, unless otherwise expressly specified and limited, the first feature "above" or "below" the second feature may include direct contact between the first and second features, or contact between the first and second features not in direct contact but through another feature between them.

[0055] Furthermore, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Additionally, the term "comprising" and any variations thereof mean "at least including."

[0056] Example 1

[0057] like Figure 1 As shown, the low K in this embodiment B The white-light ACEL device consists of a dual-color conversion layer 1, a transparent substrate 2, a transparent bottom electrode 3, a light-emitting layer 4, a dielectric layer 5, and an opaque top electrode 6, arranged sequentially from top to bottom. The dual-color conversion layer 1 comprises an R phosphor region 11 and a G phosphor region 12. The R phosphor is CASN:Eu phosphor, and the G phosphor is green LuAG:Ce phosphor. The transparent substrate 2 is colorless PI, the transparent bottom electrode 3 is ITO, the light-emitting layer 4 is blue electroluminescent phosphor ZnS:Cu, the dielectric layer 5 is barium titanate (BaTiO3), and the opaque top electrode 6 is Ag.

[0058] The dual-color conversion layer 1 is formed by uniformly mixing R phosphor and G phosphor with binder at a weight ratio of 1.4:1, and then adding 3% diluent by weight to adjust the ink consistency. This mixture is then printed sequentially on the back of the transparent substrate 2 according to the area ratio covering the light-emitting layer 4, with the sum of the two layers covering the entire area of ​​the light-emitting layer 4. Both the R phosphor area 11 and the G phosphor area 12 are printed in two layers and cured at 120℃ for 20 minutes. Similarly, ZnS:Cu and barium titanate (BaTiO3) are mixed uniformly with binder and then printed sequentially as the light-emitting layer and dielectric layer, respectively, and cured. Specifically, a transparent bottom electrode 3 is formed on the front side of the transparent substrate 2, followed by the sequential formation of the light-emitting layer 4 and dielectric layer 5 using the above printing and curing process. An opaque top electrode 6 is then formed on the dielectric layer 5, which is formed by printing conductive silver paste. Finally, the device is encapsulated to complete the fabrication of the white ACEL device.

[0059] The emission spectrum can be adjusted by changing the area ratio of the R phosphor region 11 and the G phosphor region 12 covering the emitting layer 4, thus obtaining a white-light ACEL device with a high color rendering index. The area ratio (x:y) of the R phosphor region 11 and the G phosphor region 12 is shown in the table below for fabricating ACEL devices:

[0060]

[0061] like Figure 2 As illustrated in the illustration, the effective excitation wavelength of the CASN:Eu excitation spectrum (emission 626 nm) covers the range of approximately 270 nm–580 nm, with the curve exhibiting a broadened, smoothly descending envelope shape without sharp narrow peaks. The effective excitation wavelength of the LuAG:Ce excitation spectrum (emission 527 nm) covers the range of approximately 250 nm–490 nm, with the curve exhibiting a broadened bimodal structure without sharp narrow peaks. Increasing the frequency leads to a blue shift in the emission wavelength of ZnS:Cu; that is, increasing the frequency causes a change in the excitation wavelength of the luminescent material in the dual-color conversion layer, resulting in a peak shift in the red and green photoluminescence (PL). The effect of excitation wavelengths in the 450 nm–470 nm range is more pronounced on LuAG:Ce. Figure 2 As shown, when the driving voltage is 300V and the frequency is 400Hz, the emission spectra of R0G1 and R1G are fitted using the Voigt function, and the goodness of fit is ≥0.99. The red light is 619 nm and the green light is 498 nm. There is no sharp blue light peak in the spectrum. Therefore, white light is produced by the joint emission of red and green light.

[0062] The ACEL device fabricated above was subjected to performance testing. When an alternating current was applied to the opaque top electrode 6 and the transparent bottom electrode 3, the charge carriers in the ZnS matrix gained extremely high kinetic energy. These high-energy thermionic collisions excited Cu... 2+ The luminescent center generates blue light through radiative transitions. The emitted blue light is converted into red and green light by the R and G phosphor regions, and the combined emission of red and green light forms white light. The total area of ​​the luminescent layer is uniform. When the driving voltage is 300V and the frequency is 400Hz, the spectra and spectral coordinates obtained from the above tests for devices with different area ratios are as follows: Figure 3-4 As shown, the PL spectra of the R-CCL and G-CCL of all devices exhibit CIE coordinates of (0.63, 0.36) and (0.23, 0.45), respectively. The mixed phosphor structure produces a uniform color temperature; R3G6 is approximately located on the 8000K isotherm, R5G6 on the 6000K isotherm, R6G6 and R9G6 on the 4500K isotherm, and R8G6 on the 4000K isotherm. Figure 5As shown, with the increase of the relative coverage area of ​​the R phosphor region, the red component of the device emission spectrum increases, and the voltage frequency has little effect on the CRI. When the area ratio of the R phosphor region to the G phosphor region covering the emitting layer is 6:6, the color rendering index of the white light ACEL device can reach 86 and remain basically stable.

[0063] Low K can be obtained by adjusting the driving voltage and frequency of the applied alternating current electric field. B The device is rated for a specific value. The driving voltage is fixed at 300V, and the frequency gradient is set to (50Hz ~ 400Hz); the driving frequency is fixed at 400Hz, and the voltage gradient is set to (50V ~ 300V), such as... Figure 4 As shown in the illustration, taking the R6G6 device as an example, increasing the frequency results in the CIE coordinates of R6G6 getting closer to the Planck locus, and the correlated color temperature of the spectrum getting closer to the "true color temperature." The Ki values ​​for the devices with different area ratios mentioned above... B Values ​​such as Figure 6 As shown, the K of the white ACEL device B The value is mainly related to the blue light peak value. We need to be wary of short-wavelength blue light with high energy and strong penetrating power; the 435-440nm band is the most dangerous and poses the greatest potential threat to the retina. Since the sharp blue light peak value accounts for a small proportion of the emission spectrum of white ACEL devices, the voltage-to-K value... B The value has a relatively small impact; however, increasing the frequency causes a blue shift in the emission wavelength of ZnS:Cu, affecting K. B The influence of the value is more pronounced; therefore, the smaller the frequency, the more significant the effect of K. B The smaller the value, the better. When the driving voltage is 300V and the frequency is 100Hz, the white ACEL device can still maintain a high color rendering index of 85, while K... B The value is as low as 0.3762mW / lm (compared to a standard light source of the same color temperature, this value is only 51.7% of its value).

[0064] R-phosphor and G-phosphor are uniformly coated on one side of the emitting surface of the ACEL's emitting layer in a specific area ratio to form a dual-color conversion layer. The blue light emitted by ZnS:Cu in this emitting layer under an alternating electric field is converted into red and green light by the R-phosphor and G-phosphor regions. Thanks to the broad excitation characteristics of the R-phosphor material, although the emission spectrum of the electroluminescent phosphor ZnS:Cu is affected by the driving voltage and frequency, the emission spectrum of the R-phosphor region is almost unaffected by changes in the excitation spectrum. Similarly, the spectral change of the G-phosphor region is relatively small. The white light emission spectrum can be adjusted by changing the area ratio of the R-phosphor and G-phosphor regions covering the emitting layer, thereby obtaining a white ACEL device with a high color rendering index.

[0065] In addition, the device's K B The value is mainly related to the blue light peak, while the white light spectrum formed by the co-emission of red and green light does not contain a sharp blue light peak. Since the sharp blue light peak accounts for a small proportion of the emission spectrum of white ACEL devices, the voltage affects K. B The effect of the value is small; however, increasing the frequency causes a blue shift in the wavelength of ZnS:Cu, therefore, the lower the frequency, the greater the effect of K. B The smaller the value, the better. Therefore, by adjusting the driving voltage and frequency, a low K value can be obtained. B Value-added white light ACEL devices.

[0066] Example 2

[0067] refer to Figure 7 The low-K in this embodiment B The white ACEL device consists of a transparent substrate 2, a transparent bottom electrode 3, a dual-color conversion layer 1, a light-emitting layer 4, a dielectric layer 5, and an opaque top electrode 6, arranged sequentially. The dual-color conversion layer 1 is composed of an R phosphor region 11 and a G phosphor region 12. The difference between this embodiment and Embodiment 1 is that the dual-color conversion layer 1 is located between the transparent bottom electrode 3 and the light-emitting layer 4. The rest is the same as in Embodiment 1. This embodiment achieves the same technical effect: the blue light emitted by ZnS:Cu in the light-emitting layer under an alternating electric field is converted into red and green light by phosphors R and G, which are then emitted together to form white light. Similarly, a low Kk concentration can be obtained by adjusting the area ratio of different colored phosphors in the dual-color conversion layer and controlling the alternating current. B High color rendering index, white ACEL device.

[0068] The device fabrication method in this embodiment includes the following steps:

[0069] A transparent bottom electrode is formed on a transparent substrate;

[0070] On a transparent substrate, R phosphor areas and G phosphor areas are printed separately according to the area ratio to form a two-color conversion layer; R phosphor is added to the binder at a weight ratio of 1.4:1, and 3% of the total weight of diluent is added and mixed evenly to adjust the ink consistency. The printed layer is fixed as two layers, and then dried and cured at a temperature of 120℃ for 20 minutes to obtain the R phosphor area; then the G phosphor area is formed using the same method.

[0071] ZnS:Cu electroluminescent fluorescent material is printed on the formed two-color conversion layer, dried and cured to form a light-emitting layer; ZnS:Cu is added to the binder at a weight ratio of 1.4:1, and a diluent is added at 3% of the total weight to mix evenly and adjust the ink viscosity for printing;

[0072] A high-dielectric material is printed on the light-emitting layer to form a dielectric layer;

[0073] An opaque top electrode is formed on the dielectric layer;

[0074] Packaging completes the fabrication of the white-light ACEL device.

[0075] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of this application can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0076] The above embodiments are only used to further illustrate a white light alternating current electroluminescent device and its preparation method according to the present invention. However, the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A white light alternating current electroluminescent device, characterized in that: The device includes a transparent substrate, a transparent bottom electrode, a light-emitting layer, a dielectric layer, and an opaque top electrode arranged in sequence. The light-emitting layer includes an electroluminescent material, and one side of the transparent substrate is the light-emitting surface. It also includes a dual-color conversion layer, which is located on the light-emitting side of the light-emitting layer and includes a first photoluminescent material region and a second photoluminescent material region of different colors. The light-emitting layer emits a first color of light under the drive of an alternating electric field, and the dual-color conversion layer is excited by the first color of light to generate a second color of light and a third color of light, which are emitted together to form white light.

2. The white light alternating current electroluminescent device according to claim 1, characterized in that: The dual-color conversion layer is disposed between the transparent bottom electrode and the light-emitting layer.

3. The white light alternating current electroluminescent device according to claim 1, characterized in that: The dual-color conversion layer is disposed on the side of the transparent substrate opposite to the transparent bottom electrode.

4. The white light alternating current electroluminescent device according to claim 1, characterized in that: The first photoluminescent material region and the second photoluminescent material region respectively adopt a medium-width excitation spectrum material or a wide excitation spectrum material.

5. The white light alternating current electroluminescent device according to claim 1, characterized in that: The first color of light is blue light, the second color of light is red light, and the third color of light is green light.

6. The white light alternating current electroluminescent device according to claim 5, characterized in that: The area ratio of the first photoluminescent material region to the second photoluminescent material region ranges from 3:6 to 9:

6.

7. The white light alternating current electroluminescent device according to claim 5, characterized in that: The emission spectrum is adjusted by regulating the area ratio of the first and second photoluminescent material regions covering the light-emitting layer, and K is adjusted by regulating the driving voltage or frequency of the alternating current electric field. B value.

8. The white light alternating current electroluminescent device according to claim 7, characterized in that: The electroluminescent material is ZnS:Cu; the driving voltage of the alternating electric field is 50V ~ 300V, and the frequency is 50Hz ~ 400Hz.

9. A method for preparing a white light-emitting alternating current electroluminescent device according to any one of claims 1 to 8, characterized in that: A transparent bottom electrode, a light-emitting layer, a dielectric layer, and an opaque top electrode are sequentially formed on one side of a transparent substrate; the process also includes forming a dual-color conversion layer, which is formed before the light-emitting layer or on the other side of the transparent substrate in a stacking order.

10. The method for fabricating a white light-emitting alternating current electroluminescent device according to claim 9, characterized in that: The dual-color conversion layer is formed on the surface of the transparent substrate or the surface of the transparent bottom electrode through a printing process.

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