CN111554819B - Light-emitting device, method for adjusting light-emitting color thereof, and display device - Google Patents

Abstract

The present application relates to a light-emitting device, a method for adjusting its light-emitting color, and a display device, including a substrate, a first electrode, a first light-emitting unit, a second electrode, a second light-emitting unit, and a third electrode. One of the first light-emitting unit and the second light-emitting unit is a color-changing unit, and the other is a color-fixed unit, and the light-emitting color of the color-changing unit changes with the change of the driving voltage parameter. By changing the connection mode between the second electrode, the first electrode and the third electrode and the power supply, the first light-emitting unit and the second light-emitting unit can work simultaneously, and the light-emitting device can realize high-efficiency, high-brightness white light emission with the change of the driving voltage parameters ; Or make the first light-emitting unit and the second light-emitting unit work in turn, with the change of the driving voltage parameters, so that the light-emitting device has a full-color adjustable light-emitting color. At the same time, the light-emitting layers of the first light-emitting unit and the second light-emitting unit do not need to be patterned, so it is easy to realize high-resolution and large-area display.

Description

Light-emitting device, method for adjusting light-emitting color thereof, and display device

technical field

The present application relates to the field of light-emitting diodes, in particular to a light-emitting device, a method for adjusting its light-emitting color, and a display device.

Background technique

With the development of quantum dot materials and the progress of device manufacturing technology, the performance of quantum dot light-emitting diodes (Quantum DotLight Emitting Diodes, QLED) has made great progress, such as efficiency, brightness and life, but the current practical application of QLED in full-color displays There are still obstacles in the application: to realize full-color QLED display, the light-emitting layer needs to be patterned, but the quantum dot pixel patterning technology is immature. For example, inkjet printing technology has poor film quality, low resolution, and poor uniformity. It is difficult to achieve high resolution and large-area display; in order to avoid the above-mentioned problems, the method of superimposing color filters can be used to achieve full-color display, but it is necessary to use color filter filters to filter white light and restore the three primary colors of red, green and blue. The loss of white light is large and the efficiency Low.

Therefore, the current practical application of QLED in full-color displays has the problems of large white light loss, low efficiency, and difficulty in achieving high-resolution and large-area display.

Contents of the invention

Embodiments of the present application provide a light-emitting device, a method for adjusting its light-emitting color, and a display device, which can realize high-resolution and large-area display, and can adjust the full-color light-emitting color to obtain high-efficiency white light emission.

A light emitting device comprising:

base;

The first electrode, the first light-emitting unit, the second electrode, the second light-emitting unit and the third electrode are sequentially stacked on the substrate; wherein:

The second electrode is a transparent conductive electrode;

One of the first light emitting unit and the second light emitting unit is a color changing unit, and one of the first light emitting unit and the second light emitting unit is a color fixing unit, and the color changing unit includes a second A quantum dot light-emitting layer, the light-emitting color of the first quantum dot light-emitting layer changes with the change of the driving voltage parameter.

In one of the embodiments, the first quantum dot light emitting layer includes a stacked red quantum dot light emitting layer and a green quantum dot light emitting layer; or

The material of the first quantum dot light-emitting layer includes a mixed light-emitting material of red quantum dots and green quantum dots.

In one of the embodiments, the first light emitting unit is the color changing unit, and the color changing unit further includes:

a first hole injection layer stacked on a side of the first electrode away from the substrate;

The first hole transport layer is stacked on the side of the first hole injection layer away from the substrate, and the first quantum dot light-emitting layer is stacked on the side of the first hole transport layer away from the substrate. side;

The first electron transport layer is stacked on the side of the first quantum dot light-emitting layer away from the substrate.

In one of the embodiments, the color fixing unit includes a second quantum dot light-emitting layer or an organic light-emitting layer.

In one embodiment, the material of the second quantum dot light-emitting layer includes blue quantum dot light-emitting material, and the material of the organic light-emitting layer includes blue organic light-emitting material.

In one of the embodiments, the color fixing unit further includes:

The second hole injection layer, the second hole transport layer, the second electron transport layer and the electron injection layer; wherein:

The second hole injection layer and the second hole transport layer are sequentially stacked on the side of the second electrode away from the substrate;

The second quantum dot light-emitting layer or the organic light-emitting layer is stacked on the side of the second hole transport layer away from the substrate;

The second electron transport layer and the electron injection layer are sequentially stacked on the side of the second quantum dot light-emitting layer or the organic light-emitting layer away from the substrate.

In one of the embodiments, the material of the second electrode includes transparent conductive oxide; and/or the thickness of the second electrode is 50nm-120nm.

In one of the embodiments, at least one of the first electrode and the third electrode is a transparent electrode.

In one embodiment, the material of the transparent electrode includes one of transparent conductive oxide and conductive metal.

In one of the embodiments, the light emitting device further includes:

A sputtering buffer layer is arranged between the first light emitting unit and the second electrode.

In one of the embodiments, the sputtering buffer layer includes one or a stack of the metal layer and the ZnO-based nanoparticle layer.

In one embodiment, the metal layer has a thickness of 1 nm-5 nm, and the ZnO-based nanoparticle layer has a thickness of 40 nm-100 nm.

A method for adjusting the emission color, for adjusting the emission color of the above-mentioned light emitting device, comprising:

short-circuiting the first electrode and the third electrode to the first end of the AC power supply, and connecting the second electrode to the second end of the AC power supply;

adjusting the driving voltage parameters of the AC power supply to adjust the light emitting color of the light emitting device; or

connecting the first electrode to the first terminal of the DC power supply, and connecting the third electrode to the second terminal of the DC power supply;

Adjusting the driving voltage parameters of the DC power supply to adjust the light emitting color of the light emitting device.

A display device includes the above-mentioned light emitting device.

The above-mentioned light-emitting device, its light-emitting color adjustment method, and display device include a substrate, a first electrode, a first light-emitting unit, a second electrode, a second light-emitting unit, and a third electrode. Wherein, one of the first light emitting unit and the second light emitting unit is a color changing unit, and one of the first light emitting unit and the second light emitting unit is a color fixing unit, and the light emitting of the color changing unit The color changes with the driving voltage parameter. By changing the connection mode between the second electrode, the first electrode, and the third electrode and the power supply, on the one hand, DC voltage driving can be realized, so that the first light-emitting unit and the second light-emitting unit can work at the same time. With the change of the driving voltage parameters, the light-emitting The device realizes high-efficiency, high-brightness white light emission, which can be applied to white light lighting; on the other hand, it can realize AC voltage drive, so that the first light-emitting unit and the second light-emitting unit work in turn, and the light-emitting device has Full-color adjustable luminous color, can be applied to full-color displays. At the same time, the light-emitting layers of the first light-emitting unit and the second light-emitting unit do not need to be patterned, so it is easy to realize high-resolution and large-area display.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present application. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic structural view of a light emitting device in an embodiment;

Fig. 2 is a schematic structural diagram of a light emitting device in an embodiment;

Fig. 3 is a schematic structural diagram of a light emitting device in an embodiment;

Fig. 4 is a schematic structural diagram of a first light-emitting unit in an embodiment;

Fig. 5 is a schematic structural diagram of a second light emitting unit in an embodiment;

Fig. 6 is a schematic structural diagram of a light emitting device in an embodiment;

Fig. 7 is a flow chart of a method for adjusting the emission color of a light emitting device in an embodiment;

Fig. 8 is a schematic structural diagram of a light emitting device in an embodiment;

Fig. 9 is a schematic circuit diagram of an AC-driven light emitting device in an embodiment;

Fig. 10 is a schematic circuit diagram of a DC-driven light emitting device in an embodiment;

Fig. 11 is a schematic diagram of the electroluminescence spectrum of the light-emitting device driven by alternating current and the corresponding CIE coordinates and driving signals in one embodiment;

Fig. 12 is a color gamut diagram achievable by a light emitting device in an embodiment;

Fig. 13 is an electroluminescence spectrum diagram of a light-emitting device driven by direct current in one embodiment;

Fig. 14 is a graph of the current density-voltage-brightness characteristic curve of the light-emitting device under DC driving in an embodiment;

Fig. 15 is a graph showing the external quantum efficiency-current density characteristic curve of the light-emitting device driven by direct current in one embodiment.

Detailed ways

In order to make the purpose, technical solution and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not intended to limit the present application.

It can be understood that the terms "first", "second" and the like used in this application may be used to describe various elements herein, but these elements are not limited by these terms. These terms are only used to distinguish one element from another element. For example, a first electrode could be termed a second electrode, and, similarly, a second electrode could be termed a first electrode, without departing from the scope of the present application. Both the first electrode and the second electrode are electrodes, but they are not the same electrode.

Please refer to FIG. 1 . FIG. 1 shows a schematic structural diagram of a light emitting device provided in this embodiment.

In this embodiment, the light-emitting device 10 includes: a substrate 101 ; a first electrode 102 , a first light-emitting unit 103 , a second electrode 104 , a second light-emitting unit 105 and a third electrode 106 are sequentially stacked on the substrate 101 .

In this embodiment, the substrate 101 can be a glass substrate, or a ceramic substrate or a plastic flexible substrate according to actual conditions.

In this embodiment, the first electrode 102, the second electrode 104 and the third electrode 106 are used in combination: in one embodiment, the second electrode 104 can be used as the first control electrode of the light emitting device and the first end of the AC power supply connection, the first electrode 102 and the third electrode 106 are short-circuited as the second control electrode of the light-emitting device and connected to the second end of the AC power supply, so that the first light-emitting unit 103 and the second light-emitting unit 105 are connected in antiparallel (refer to 2 ), to realize AC voltage driving, at this time the first light-emitting unit 103 and the second light-emitting unit 105 work in turn, so that the light-emitting device has a full-color adjustable light-emitting color. In another embodiment, the second electrode 104 is a transparent conductive electrode, which has an energy level matching that of the first light-emitting unit 103 and the second light-emitting unit 105. As an intermediate connecting layer of the stack, the first light-emitting unit 103 and the second light-emitting unit 103 can be connected to each other. The two light-emitting units 105 are connected, while the first electrode 102 and the third electrode 106 are respectively connected to two ends of the DC power supply, so that the first light-emitting unit 103 and the second light-emitting unit 105 are effectively connected in series (see FIG. 3 ), realizing Driven by DC voltage, the first light emitting unit 103 and the second light emitting unit 105 work at the same time, so that the light emitting device can emit white light with high efficiency and high brightness.

In one embodiment, the material of the second electrode 104 includes a transparent conductive oxide, such as one of indium-doped tin oxide (ITO), aluminum-doped zinc oxide (AZO) and indium-doped zinc oxide (IZO), or Various, so that the second electrode 104 has good light transmittance and conductivity; in one embodiment, the thickness of the second electrode 104 is 50nm-120nm, so that while having good electrical properties, it also has high the transmittance. More specifically, when driven by AC, the light-emitting device is used as a color-changing device to realize the full-color tunable function of the luminous color, and the thickness of the second electrode 104 can be set to 50nm-120nm; when driven by DC, the light-emitting device is used as a white light device to achieve high efficiency. For high-brightness white light emission, the thickness of the second electrode 104 can be set to 50nm-120nm.

In one embodiment, at least one of the first electrode 102 and the third electrode 106 is a transparent electrode, and the material of the transparent electrode includes one of transparent conductive oxide and conductive metal. Specifically, when only the first electrode 102 is a transparent electrode, the light-emitting device can be formed as a bottom-emitting device; when only the third electrode 106 is a transparent electrode, the light-emitting device can be formed as a top-emitting device. , higher luminous power can be obtained at the same current density; when the first electrode 102 and the third electrode 106 are both transparent electrodes, the light-emitting device is a transparent light-emitting device, which can be applied in transparent displays. Therefore, light emitting devices of different emission types can be formed by selecting the materials of the first electrode 102 and the third electrode 106, so as to expand the actual demand of the light emitting device and be applicable to more display occasions.

Among them, the transparent conductive oxide includes one or more of indium-doped tin oxide (ITO), aluminum-doped zinc oxide (AZO) and indium-doped zinc oxide (IZO); the conductive metal includes silver and silver-magnesium alloy One or more of, for example, one or more of Ag nanowires, thin-layer Ag, thin-layer Ag:Mg and other metal nanowires, and thin-layer metals.

In this embodiment, one of the first light emitting unit 103 and the second light emitting unit 105 is a color changing unit, and one of the first light emitting unit 103 and the second light emitting unit 105 is a color fixed unit, and the color changing unit includes The first quantum dot light-emitting layer, the light-emitting color of the first quantum dot light-emitting layer changes with the change of the driving voltage parameter.

Among them, the color changing unit can change the luminescent color according to the driving voltage parameters of the power supply, for example, emit red light, yellow light or green light with the change of the driving voltage parameters; the color fixing unit maintains the same color with the driving voltage, for example, Parameter changes keep glowing blue. Wherein, the driving voltage parameters include voltage amplitude, duty cycle and frequency, and the frequency is generally above 50HZ. Therefore, through the mutual combination of the color changing unit and the color fixing unit, lights of different colors can be mixed in different proportions, so that the light emitting device has full-color adjustable luminescent colors, and high-efficiency white light emission can also be realized. At the same time, the light-emitting layers of the first light-emitting unit and the second light-emitting unit do not need to be patterned, so it is easy to realize high-resolution and large-area display.

Exemplarily, the first light emitting unit 103 is a color changing unit, and the second light emitting unit 105 is a color fixing unit:

In one embodiment, the first light-emitting unit 103 is a single-functional layer structure, including a first quantum dot light-emitting layer, and the first quantum dot light-emitting layer is arranged between the first electrode 102 and the second electrode 104, thereby achieving thinner light-emitting The unit effectively simplifies the manufacturing process of the light-emitting device.

In one embodiment, the first light emitting unit 103 is a multifunctional layer structure, so as to further improve the photoelectric characteristics. Referring to FIG. 4 , the first light emitting unit 103 includes a first quantum dot light emitting layer 301 , and further includes: a first hole injection layer 302 , a first hole transport layer 303 and a first electron transport layer 304 . Wherein, the first hole injection layer 302 is stacked on the side of the first electrode away from the substrate; the first hole transport layer 303 is stacked on the side of the first hole injection layer 302 away from the substrate; the first quantum dots The light emitting layer 301 is stacked on the side of the first hole transport layer 303 away from the substrate 101 ; the first electron transport layer 304 is stacked on the side of the first quantum dot light emitting layer 301 away from the base.

Wherein, the material and thickness of each functional layer of the first hole injection layer 302 , the first hole transport layer 303 and the first electron transport layer 304 are not limited here, as long as the functions of each functional layer can be realized. At the same time, the first light-emitting unit can also add functional layers or reduce functional layers therein according to actual conditions.

In one embodiment, the second light-emitting unit 105 is a single-functional layer structure, including a second quantum dot light-emitting layer or an organic light-emitting layer, so as to realize a thinner light-emitting unit and effectively simplify the manufacturing process of the light-emitting device.

In one embodiment, the second light emitting unit 105 is a multifunctional layer structure, so as to further improve the photoelectric characteristics. Referring to Fig. 5, the second light-emitting unit 105 includes a second quantum dot light-emitting layer or an organic light-emitting layer 401, and also includes: a second hole injection layer 402, a second hole transport layer 403, a second electron transport layer 404, and electron Inject layer 405 . Wherein, the second hole injection layer 402 and the second hole transport layer 403 are sequentially stacked on the side of the second electrode 104 away from the substrate; the second quantum dot light-emitting layer or organic light-emitting layer 401 is stacked on the second hole transport layer The layer 403 is away from the substrate; the second electron transport layer 404 and the electron injection layer 405 are sequentially stacked on the side of the second quantum dot light-emitting layer or organic light-emitting layer 401 away from the substrate.

Wherein, the material and thickness of each functional layer of the second hole injection layer 402, the second hole transport layer 403, the second electron transport layer 404 and the electron injection layer 405 are not limited here, as long as the functions of each functional layer can be realized That's it. At the same time, the second light emitting unit 105 can also add functional layers (such as adding an electron blocking layer between the organic light emitting layer and the second hole transport layer) or reduce the functional layers therein according to actual conditions.

In one embodiment, the first quantum dot light emitting layer includes a stacked red quantum dot light emitting layer and a green quantum dot light emitting layer; or the material of the first quantum dot light emitting layer includes a mixed light emitting material of red quantum dots and green quantum dots. Therefore, through the red quantum dots and the green quantum dots, the luminescent color of the first quantum dot light-emitting layer changes with the change of the driving voltage parameter.

In one embodiment, the material of the second quantum dot light-emitting layer includes blue quantum dot light-emitting material, and the material of the organic light-emitting layer includes blue organic light-emitting material. Therefore, the blue quantum dot luminescent material of the second quantum dot luminescent layer realizes blue light emission under voltage driving, and the blue organic light emitting material of the organic light emitting layer realizes blue light emission under voltage driving. Among them, the blue quantum dot luminescent material has a better color gamut than the blue organic luminescent material.

In one embodiment, the quantum dot luminescent material includes at least one of CdSe-based nano-luminescent material and InP-based nano-luminescent material; the organic luminescent material includes at least one of organic phosphorescent luminescent material, organic fluorescent luminescent material and organic delayed fluorescent luminescent material. A sort of.

It should be noted that the formation process of the above layers is not limited, including laser etching, spin coating method, evaporation method, radio frequency magnetron sputtering, thermal evaporation and full solution method and other formation processes. For example, the substrate is patterned by laser etching, the first electrode and the second electrode are deposited by sputtering, the functional layers of the first light-emitting unit and the second light-emitting unit are deposited by spin coating, and the third electrode is deposited by thermal evaporation. . It can be understood that the forming process can be selected and adjusted according to actual application conditions and product performance, and no further limitation is made here.

The light emitting device provided in this embodiment includes a substrate, a first electrode, a first light emitting unit, a second electrode, a second light emitting unit and a third electrode. Wherein, one of the first light emitting unit and the second light emitting unit is a color changing unit, and one of the first light emitting unit and the second light emitting unit is a color fixing unit, and the light emitting color of the color changing unit varies with the change of the driving voltage parameter Variety. By changing the connection mode between the second electrode, the first electrode and the third electrode and the power supply, on the one hand, DC voltage driving can be realized, so that the first light-emitting unit and the second light-emitting unit can work at the same time, and the light-emitting device can be realized by changing the driving voltage parameters. High-efficiency, high-brightness white light emission, which can be applied to white light lighting; on the other hand, it can realize AC voltage drive, so that the first light-emitting unit and the second light-emitting unit work in turn, and the light-emitting device has a full color with the change of the driving voltage parameters. Adjustable luminous color, can be applied to full-color display. At the same time, the light-emitting layers of the first light-emitting unit and the second light-emitting unit do not need to be patterned, so it is easy to realize high-resolution and large-area display.

Please refer to FIG. 6 . On the basis of FIG. 1 , FIG. 6 shows a schematic structural diagram of another light emitting device provided by this embodiment.

In this embodiment, the light-emitting device 20 includes: a substrate 201; a first electrode 202, a first light-emitting unit 203, a second electrode 204, a second light-emitting unit 205, and a third electrode 206 that are sequentially stacked on the substrate 201; It also includes a sputtering buffer layer 207 disposed between the first light emitting unit 203 and the second electrode 204 to protect the first light emitting unit 203 from being damaged when the second electrode 204 is prepared by sputtering.

In one embodiment, the sputtering buffer layer 207 includes one or a stack of the metal layer and the ZnO-based nanoparticle layer. Since metal and ZnO-based nanoparticles have electrical conductivity, it is beneficial to the transport of charges, so that when the sputtering buffer layer 207 resists the bombardment of the sputtering second electrode 204 process and prevents the penetration of atoms, it will not affect the electrical properties of the first light-emitting unit 203. Performance and optical performance are negatively affected. Therefore, in this embodiment, by setting the sputtering buffer layer 207, the photoelectric performance of the first light emitting unit 203 can be improved while protecting the first light emitting unit 203, thereby further improving the stability and photoelectric performance of the light emitting device.

In one embodiment, the thickness of the metal layer is 1nm-5nm, and the metal layer can be an Al layer, such as an Al ultra-thin metal film, so as to further improve the photoelectric performance of the first light-emitting unit while protecting the first light-emitting unit; ZnO-based The nanoparticle layer has a thickness of 40nm-100nm, so as to further improve the photoelectric performance of the first light-emitting unit while protecting the first light-emitting unit.

It should be noted that, for the substrate 201, the first electrode 202, the first light emitting unit 203, the second electrode 204, the second light emitting unit 205 and the third electrode 206, please refer to the substrate 101, the first electrode 102, the second electrode 206 in the previous embodiment. A light-emitting unit 103 , the second electrode 104 , the second light-emitting unit 105 and the third electrode 106 are described, and will not be repeated here.

Please refer to FIG. 7 . FIG. 7 shows a flow chart of the method for adjusting the light emission color of the light emitting device provided in the above embodiment. The adjustment method includes step 701 to step 704 . specifically:

Step 701, short-circuit the first electrode and the third electrode and connect to the first terminal of the AC power supply, and connect the second electrode to the second terminal of the AC power supply.

Step 702, adjusting the driving voltage parameters of the AC power supply to adjust the light emitting color of the light emitting device.

Step 703, connect the first electrode with the first terminal of the DC power supply, and connect the third electrode with the second terminal of the DC power supply.

Step 704, adjusting the driving voltage parameters of the DC power supply to adjust the light emitting color of the light emitting device.

In this embodiment, through steps 701 to 702, the light-emitting device can have a full-color adjustable light-emitting color. For the specific connection method of each electrode of the light-emitting device, please refer to Figure 2 of the above-mentioned embodiment, and will not be repeated here; through the steps From step 703 to step 704, the light-emitting device can realize high-efficiency, high-brightness white light emission. For the specific connection method of each electrode of the light-emitting device, please refer to FIG. 3 of the above-mentioned embodiment, and will not be repeated here.

It should be understood that although the various steps in the flow chart of FIG. 7 are displayed sequentially as indicated by the arrows, these steps are not necessarily executed sequentially in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders.

The following are the specific implementation methods in the above-mentioned embodiments. It should be noted that the above-mentioned embodiments are not limited to the following specific embodiments, and can be appropriately modified and implemented within the scope of not changing the main right:

Example 1

Fig. 8 is a schematic structural diagram of the light emitting device provided by this embodiment.

The light-emitting device is sequentially stacked with a glass substrate 801 , a first electrode 802 , a first light-emitting unit 803 , a sputtering buffer layer 804 , a second electrode 805 , a second light-emitting unit 806 and a third electrode 807 .

Wherein, the first light emitting unit 803 is a color changing unit, and is a color adjustable QLED, including a hole injection layer 8031, a hole transport layer 8032, a first quantum dot light emitting layer 8033 and an electron transport layer 8034; the second light emitting unit 806 is a color fixing unit, which is a fluorescent blue OLED, including a hole injection layer 8061 , a hole transport layer 8062 , an organic light emitting layer 8063 , an electron transport layer 8064 and an electron injection layer 8065 .

Wherein, the glass substrate 801 and the first electrode 802 (transparent electrode) are ITO glass substrates patterned by laser ablation or photolithography.

Wherein, the hole injection layer 8031 is a poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) film, and its preparation method is as follows: The PEDORT:PSS solution was spin-coated at 3000r/min to form a film, and then baked at 150°C for 15min. The hole transport layer 8032 is poly[(N,N'-(4-n-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine)-ALT-(9,9-di n-octylfluorenyl-2,8-diyl)]Poly[(9,9-dioctylfluorenyl-2,8-diyl)-co(4,4-(N-(p-butylphenyl))diphenylamine)]

(TFB) film, its preparation method is: the chlorobenzene solution of 8mg/ml TFB is spin-coated at the speed of 3000r/min to form a film, then baked at 110°C for 10min.

Among them, the first quantum dot light-emitting layer 8033 is a mixed film of CdSe/ZnS core-shell structure red quantum dots and green quantum dots, and its preparation method is: 10mg/mL red quantum dot n-octane solution and 10mg/mL green The n-octane solution of quantum dots is configured into a mixed solution of red quantum dots and green quantum dots with a ratio of 1:20 (color-changing device) or 1:9 (white light device) according to different volume ratios, and at a speed of 3000r/min Spin-coat to form a film, and then bake at 100°C for 5min.

Wherein, the electron transport layer 8034 is a ZnMgO nanoparticle thin film, which is prepared by spin-coating a 20mg/ml ethanol solution of ZnMgO nanoparticles at a speed of 2500r/min, and then baking at 100°C for 10min.

Among them, the sputtering buffer layer 804 is a 2nm Al ultra-thin metal film prepared by evaporation; the second electrode 805 is a 60nm (color-changing light-emitting device) or 80nm (white light-emitting device) IZO transparent oxide film prepared by sputtering. object film.

Wherein, the material of the hole injection layer 8061 is molybdenum trioxide (MoO ₃ ) with a thickness of 8 nm; the material of the hole transport layer 8062 is N,N'-[bis(1-naphthyl)-N,N'-di Phenyl]-1,1'-bisphenyl)-4,4'-diamineN,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4, 4″-diamine (NPB), with a thickness of 45nm; the material of the organic light-emitting layer 8063 is 9,10-di(2-naphthyl)-2-methylanthracene 2-methyl-9,10-di(2-naphthyl) anthracene (MADN) and 4,4′-[1,4-phenylenebis-(1E)-2,1-ethylenediyl]bis[N,N-diphenylaniline]9,10-p-bis (pN, N-diphenyl-aminostyryl) benzene (DSA-Ph) mixed film (DSA-Ph/MADN=12%), its thickness is 25nm; the material of the electron transport layer 8064 is 2,2′,2″-( 1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole (TPBi), with a thickness of 40nm; the electron injection layer 8065 is made of lithium fluoride (LiF), with a thickness of 1nm.

Wherein, the third electrode 807 is a 100 nm Al electrode prepared by thermal evaporation.

Please refer to FIGS. 9-10 in combination. FIG. 9 is a schematic circuit diagram of an AC-driven light emitting device provided in this embodiment, and FIG. 10 is a circuit schematic diagram of a DC-driven light emitting device provided in this embodiment.

Please refer to FIG. 11-FIG. 12 in combination. FIG. 11 is a schematic diagram of the electroluminescent spectrum of the light-emitting device provided in this embodiment under the driving of an alternating current and the corresponding CIE coordinates and driving signals; FIG. 12 is a schematic diagram of the light-emitting device provided in this embodiment. Realized gamut map.

It can be seen from Figure 11-Figure 12 that by controlling the parameters such as the amplitude, duty cycle and frequency of the AC power supply, the luminous color of the device can be changed from red to green, green to blue, blue to red and blue to blue. Orange variations, achievable color gamut up to 63% NTSC.

Please refer to Figure 13-Figure 15 in combination, Figure 13 is the electroluminescence spectrum diagram of the light-emitting device provided in this embodiment under DC driving; Figure 14 is the current density-voltage-voltage of the light-emitting device provided in this embodiment under DC driving Luminance characteristic curve; FIG. 15 is the external quantum efficiency-current density characteristic curve of the light-emitting device provided in this embodiment under direct current driving.

It can be seen from the figure that the light-emitting device is driven by a DC power supply, and the parameters such as the emission spectrum, current-voltage characteristics and external quantum efficiency of the first light-emitting unit (red-green QLED) and the second light-emitting unit (blue OLED) are obtained. Very good stacking (stacked white light) indicates that the second electrode has excellent electrical properties and can well connect the first light-emitting unit and the second light-emitting unit in series. The light-emitting device successfully achieved a high-brightness white light emission of 107K cd/m ² and a high external quantum efficiency of 16.91%.

Example 2

The only difference between this embodiment and Embodiment 1 is that the second light-emitting unit is a phosphorescent blue OLED, which includes a hole injection layer, a hole transport layer, an electron blocking layer, an organic light-emitting layer, an electron transport layer, and an electron barrier layer stacked in sequence. The injection layer is prepared by thermal evaporation.

Wherein, the material of the hole injection layer is 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene dipyrazino[2,3-f :2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HATCN), with a thickness of 20nm. The material of the hole transport layer is 1,1-bis[4-[N,N-bis(p-toluene)amino]phenyl]cyclohexane 1,1-bis[4-[N,N-di(p- tolyl)aminophenyl]cyclohexane (TAPC) with a thickness of 40nm. The material of the electron blocking layer is 1,3-dicarbazol-9-ylbenzene 1,3-bis(9-carbazolyl)benzene (mCP), and the thickness is 5 nm. The material of the organic light-emitting layer is bis(4,6-difluorophenylpyridine-C2,N)pyridinium iridium Bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III )(Firpic) and 9-(3-(9H-carbazole-9-yl)phenyl)-3-(dibromophenylphosphoryl)-9H-carbazole(mCPPO1) mixed thin film (Firpic/mCPPO1=8%) with a thickness of 30 nm . The material of the electron transport layer is 1,3,5-tris[(3-pyridinyl)-3-phenyl]benzene 1,3,5-Tri(m-pyridin-3-ylphenyl)benzene)(TmPyPB), the thickness 30nm. The electron injection layer is made of lithium fluoride (LiF) with a thickness of 1 nm.

Compared with the fluorescent blue OLED in Example 1, the phosphorescent blue OLED used in the second light-emitting unit of Example 2 has higher luminous efficiency, so that the overall luminous efficiency of the light-emitting device is higher.

Example 3

The only difference between this embodiment and Embodiment 1 is that the first electrode is a reflective electrode based on Al/ITO, which is prepared by sputtering; the third electrode is a transparent electrode, which adopts Ag:Mg thin layer metal with a thickness of 15nm, using Made by vapor deposition.

Compared with the bottom-emitting device of Example 1, Example 3 is a top-emitting device, which has a larger aperture ratio and can obtain higher luminous power at the same current density.

Example 4

The only difference between this embodiment and embodiment 1 is that the second electrode is an ITO thin film of 60nm-80nm, prepared by sputtering.

Compared with the IZO transparent oxide film used in the second electrode of Example 1, the ITO film used in the second electrode of Example 4 also has excellent light transmittance and electrical conductivity, so that the overall device has higher luminous efficiency and photoelectric characteristics. .

Example 5

The difference between this embodiment and Embodiment 1 is that the second light-emitting unit is a blue QLED, which includes a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, and an electron transport layer stacked in sequence, and is prepared by a full solution method. .

Wherein, the material of the hole injection layer is poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS), and its preparation method is: The PEDORT:PSS solution was spin-coated at 3000r/min to form a film, and then baked at 150°C for 15min. The material of the hole transport layer is poly[(N,N'-(4-n-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine)-ALT-(9,9- Din-octylfluorenyl-2,7-diyl)]Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co(4,4-(N-(p-butylphenyl))diphenylamine)]( TFB), its preparation method is: 8 mg/ml TFB chlorobenzene solution is spin-coated at a speed of 3000 r/min to form a film, and then baked at 110° C. for 10 min. The material of the quantum dot luminescent layer is the blue color quantum dot of CdSe/ZnS core-shell structure, and its preparation method is: the n-octane solution of 10mg/mL blue quantum dot is spin-coated with the speed of 3000r/min to form a film, and then with Bake at 100°C for 5 minutes. The material of the electron transport layer is a ZnMgO nanoparticle thin film, and its preparation method is: spin coating a 20mg/ml ethanol solution of ZnMgO nanoparticles at a speed of 2500r/min to form a film, and then bake at 100°C for 10min.

Compared with the fluorescent blue OLED in Example 1, the blue QLED used in the second light emitting unit of Example 5 further improves the color gamut of the light emitting device.

Example 6

The only difference between this embodiment and Embodiment 5 is that the third electrode is Ag nanowires, which are made by spin coating.

Compared with the bottom-emitting device of Embodiment 5, Embodiment 6 is a transparent light-emitting device, which can be applied to transparent displays.

Example 7

The difference between this embodiment and Embodiment 5 is that the quantum dot light-emitting layer of the first light-emitting unit is a blue quantum dot film, and the quantum dot light-emitting layer of the second light-emitting unit is a red and green mixed quantum dot film.

Among them, the quantum dot preparation method of the first light-emitting unit is: spin-coat the n-octane solution of blue quantum dots with 10mg/mL CdSe/ZnS core-shell structure at a speed of 3000r/min to form a film, and then bake at 100°C 5min. The quantum dot preparation method of the second light-emitting unit is as follows: the n-octane solutions of the green quantum dots with 10 mg/mL CdSe/ZnS core-shell structure and the red quantum dots with 10 mg/mL CdSe/ZnS core-shell structure are configured in different volume ratios A mixed solution of red quantum dots and green quantum dots was formed, and spin-coated at a speed of 3000r/min to form a film, and then baked at 100°C for 5min.

Compared with Embodiment 5, where the first light-emitting unit is a color-changing unit and the second light-emitting unit is a color-fixed unit, in Embodiment 7, the first light-emitting unit is a color-fixed unit and the second light-emitting unit is a color-changing unit, and the light-emitting device can also be realized The luminous color is adjustable in all colors, and high-efficiency white light emission is obtained.

This embodiment also provides a display device, including the light-emitting device as described in the above-mentioned embodiments, the display device can realize high resolution and large-area display, and the luminous color can be adjusted in full color to perform full-color display; it can also obtain High-efficiency white light emission for white light illumination.

The above-mentioned embodiments only express several implementation modes of the present application, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the scope of protection of the patent application should be based on the appended claims.

Claims (11)

1. A light emitting device, comprising:

a substrate;

a first electrode, a first light-emitting unit, a second electrode, a second light-emitting unit and a third electrode which are sequentially stacked on the substrate; wherein:

the second electrode is a transparent conductive electrode;

one of the first light emitting unit and the second light emitting unit is a color change unit, one of the first light emitting unit and the second light emitting unit is a color fixing unit, the color change unit comprises a first quantum dot light emitting layer, the color fixing unit comprises a second quantum dot light emitting layer or an organic light emitting layer, the second electrode is used as a first control electrode of the light emitting device and is connected with a first end of an alternating current power supply, the first electrode and the third electrode are in short circuit, used as a second control electrode of the light emitting device, are connected with a second end of the alternating current power supply, and accordingly the first light emitting unit and the second light emitting unit are connected in anti-parallel to achieve alternating current voltage driving, and the light emitting color of the first quantum dot light emitting layer changes along with the change of driving voltage parameters, so that the light emitting device has full-color adjustable light emitting color;

the first quantum dot light-emitting layer comprises a red quantum dot light-emitting layer and a green quantum dot light-emitting layer which are arranged in a laminated manner; or the material of the first quantum dot luminescent layer comprises a mixed luminescent material of red quantum dots and green quantum dots; the material of the second quantum dot light-emitting layer comprises a blue quantum dot light-emitting material, and the material of the organic light-emitting layer comprises a blue organic light-emitting material.

2. The light-emitting device according to claim 1, wherein the first light-emitting unit is the color-changing unit, the color-changing unit further comprising:

a first hole injection layer stacked on a side of the first electrode away from the substrate;

the first quantum dot light-emitting layer is arranged on one side of the first hole transport layer away from the substrate in a stacked manner;

and the first electron transmission layer is laminated on one side of the first quantum dot light-emitting layer far away from the substrate.

3. The light-emitting device according to claim 1, wherein the color fixing unit further comprises:

a second hole injection layer, a second hole transport layer, a second electron transport layer, and an electron injection layer; wherein:

the second hole injection layer and the second hole transport layer are sequentially stacked on one side of the second electrode away from the substrate;

the second quantum dot light-emitting layer or the organic light-emitting layer is stacked on one side of the second hole transport layer far away from the substrate;

the second electron transport layer and the electron injection layer are sequentially stacked on one side, far away from the substrate, of the second quantum dot light-emitting layer or the organic light-emitting layer.

4. A light emitting device according to any one of claims 1-3 wherein the material of the second electrode comprises a transparent conductive oxide; and/or the thickness of the second electrode is 50nm-120nm.

5. A light-emitting device according to any one of claims 1 to 3, wherein at least one of the first electrode and the third electrode is a transparent electrode.

6. The light-emitting device according to claim 5, wherein the material of the transparent electrode comprises one of a transparent conductive oxide and a conductive metal.

7. A light emitting device according to any one of claims 1-3, further comprising:

and a sputtering buffer layer disposed between the first light emitting unit and the second electrode.

8. The light emitting device of claim 7, wherein the sputter buffer layer comprises a stack of one or both of a metal layer and a ZnO-based nanoparticle layer.

9. The light-emitting device according to claim 8, wherein the thickness of the metal layer is 1nm to 5nm, and the thickness of the ZnO-based nanoparticle layer is 40nm to 100nm.

10. A light-emitting color adjustment method for adjusting a light-emitting color of a light-emitting device according to any one of claims 1 to 9, comprising:

the first electrode and the third electrode are connected with a first end of an alternating current power supply after being short-circuited, and the second electrode is connected with a second end of the alternating current power supply;

adjusting a driving voltage parameter of the alternating current power supply to adjust the light emitting color of the light emitting device; or alternatively

Connecting the first electrode with a first end of a direct current power supply, and connecting the third electrode with a second end of the direct current power supply;

and adjusting the driving voltage parameter of the direct current power supply to adjust the light emitting color of the light emitting device.

11. A display device comprising a light emitting device according to any one of claims 1 to 9.

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