CN114695689A - Display device with a light-shielding layer - Google Patents
Display device with a light-shielding layer Download PDFInfo
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- CN114695689A CN114695689A CN202011616642.6A CN202011616642A CN114695689A CN 114695689 A CN114695689 A CN 114695689A CN 202011616642 A CN202011616642 A CN 202011616642A CN 114695689 A CN114695689 A CN 114695689A
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- H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
- H10K50/115—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising active inorganic nanostructures, e.g. luminescent quantum dots
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- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
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- H10K59/12—Active-matrix OLED [AMOLED] displays
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Abstract
The invention discloses a display device, which comprises a plurality of pixel point structures, wherein each pixel point structure comprises a red-green sub pixel point unit and a blue sub pixel point unit; the red and green sub-pixel point unit comprises a first electrode, a first quantum dot light-emitting layer, a second electrode, a second quantum dot light-emitting layer and a third electrode which are sequentially stacked and arranged, wherein the first electrode, the first quantum dot light-emitting layer, the second electrode, the second quantum dot light-emitting layer and the third electrode are sequentially stacked and arranged, the second electrode is connected with a TFT (thin film transistor), the first electrode, the first quantum dot light-emitting layer and the second electrode form one of an upright light-emitting device and an inverted light-emitting device, and the second electrode, the second quantum dot light-emitting layer and the third electrode form the same one of the upright light-emitting device and the inverted light-emitting device. The red sub-pixel unit and the green sub-pixel unit are integrated into one pixel unit, so that the number of the sub-pixel units in a single pixel point structure is reduced, the area of the single pixel point structure is reduced, and the resolution of the printing display device is improved.
Description
Technical Field
The present invention relates to the field of light emitting devices, and more particularly to display devices.
Background
Quantum Dots (QDs), also known as semiconductor nanocrystals, are a new class of semiconductor nanomaterials. Because the size of the quantum confinement quantum well of luminescence is one of quantum well of quantum well has luminescence is one of quantum well quantum. The quantum dot has excellent optical characteristics of high quantum yield, good stability, high color purity, easy adjustment of luminescent color and the like, and the quantum dot electroluminescent display technology becomes the best candidate of the next generation display technology due to the advantages of adjustable wavelength, high color saturation, high material stability, low preparation cost and the like.
A quantum dot light emitting diode (QLED) is an electroluminescent device using a quantum dot material as a light emitting layer, which inherits excellent optical characteristics of the quantum dot material, has important commercial application values in the fields of display and illumination, and has attracted wide attention. With the development of nearly twenty years, the external quantum efficiency of quantum dot light emitting diodes has been promoted to over 20% via 0.01%, and quantum dot light emitting diodes (QLEDs) have come quite close to Organic Light Emitting Diodes (OLEDs) in terms of device efficiency.
The structure of the device of the QLED is similar to that of an OLED at present, a sandwich structure similar to a p-i-n junction is formed by a hole injection layer, a hole transport layer, a quantum dot light emitting layer, an electron transport layer and the like, and the effect of high-efficiency light emitting is achieved by balancing the injection of electrons and holes. Furthermore, the red, green and blue quantum dot devices are combined into a display device capable of displaying various colors. At present, an ink-jet printing process is mainly adopted in the preparation process of the QLED device, but the size of a single pixel point prepared by the process cannot be as small as that of an evaporation process, so that the improvement of the resolution of a display device is limited. The size of a single pixel point prepared by the evaporation process is regulated and controlled by the metal mask plate, so that high resolution can be achieved; however, in the inkjet printing process, the size of the pixel cannot be reduced without limit due to the limitation of the size of the droplet, so that the resolution of the prepared display device is also limited.
Therefore, the prior art is still to be improved.
Disclosure of Invention
The invention discloses a display device, and aims to solve the problem that the resolution of the prepared display device is limited due to the size limitation of a single pixel point in the prior art.
The technical scheme of the invention is as follows:
a display device comprises a plurality of pixel point structures, wherein each pixel point structure comprises a red-green sub pixel point unit and a blue sub pixel point unit;
the red and green sub-pixel point unit comprises a first electrode, a first quantum dot light-emitting layer, a second electrode, a second quantum dot light-emitting layer and a third electrode which are sequentially stacked,
the first quantum dot light emitting layer and the second quantum dot light emitting layer can emit light individually or alternately,
one of the first quantum dot light emitting layer and the second quantum dot light emitting layer can emit red light, the other can emit green light,
the second electrode is connected with a TFT thin film transistor,
the first electrode, the first quantum dot light emitting layer and the second electrode form one of an upright type light emitting device and an inverted type light emitting device, and the second electrode, the second quantum dot light emitting layer and the third electrode form the same one of the upright type light emitting device and the inverted type light emitting device.
Has the beneficial effects that: the invention discloses a display device, which integrates red light sub-pixel units and green light sub-pixel units into one pixel unit, thereby reducing the number of sub-pixel units (from 3 to 2) in a single pixel structure, reducing the area of the single pixel structure and further improving the resolution of the printed display device. The display device provided by the invention not only has higher resolution, but also simplifies the number of driving electrodes and reduces the circuit loss.
Drawings
Fig. 1 is a schematic structural diagram of a display device according to a preferred embodiment of the present invention.
Detailed Description
The present invention provides a display device, and the present invention will be described in further detail below in order to make the objects, technical solutions, and effects of the present invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It will be understood that, as used herein, the terms "first," "second," etc. may be used herein to describe various elements, but these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first electrode can be referred to as a second electrode, and similarly, a second electrode can be referred to as a first electrode, without departing from the scope of the present invention. The first electrode and the second electrode are both electrodes, but they are not the same electrode.
In the process of preparing the QLED device by ink-jet printing, due to the limitation of the size of liquid drops, the size of a pixel point cannot be reduced without limit, so that the resolution of the prepared display device is also limited.
Based on this, the present invention provides a display device, as shown in fig. 1, which includes a plurality of pixel structures, each pixel structure including a red-green sub-pixel unit 10 and a blue sub-pixel unit 20; the red and green sub-pixel unit 10 comprises a first electrode (formed on a substrate), a first quantum dot light-emitting layer, a second electrode, a second quantum dot light-emitting layer and a third electrode;
when the light emitted by the red-green sub-pixel point unit is emitted from the third electrode, the first quantum dot light emitting layer emits red light, and the second quantum dot light emitting layer emits green light;
when the light emitted by the red-green sub-pixel point unit is emitted from the first electrode, the second quantum dot light emitting layer emits red light, and the first quantum dot light emitting layer emits green light.
That is to say, the red and green sub-pixel 10 provided in this embodiment is formed by combining two quantum dot light emitting diodes with light emitting wavelengths: the LED comprises a first quantum dot light-emitting diode (composed of a first electrode, a first quantum dot light-emitting layer and a second electrode) and a second quantum dot light-emitting diode (composed of a third electrode, a second quantum dot light-emitting layer and a second electrode), wherein the first quantum dot light-emitting diode and the second quantum dot light-emitting diode are combined together through a common second electrode, one of the light-emitting wavelength of the first quantum dot light-emitting layer and the light-emitting wavelength of the second quantum dot light-emitting layer can emit red light, and the other can emit green light. The color of light is determined by the wavelength of light, and the emission wavelength differs, and the corresponding emission color differs. Therefore, it can also be said that the red and green sub-pixel unit 10 provided in this embodiment is formed by combining two colors of quantum dot light emitting diodes.
The quantum dot light emitting diodes with two colors are combined into the red and green sub-pixel point unit structure, so that the number of the quantum dot light emitting diodes in a single pixel point structure is reduced, the area of the single pixel point structure is reduced, and the resolution of a printing display device is improved. The display device provided by the embodiment has higher resolution, simplifies the number of driving electrodes and reduces circuit loss.
In this embodiment, the red and green sub-pixel unit can have multiple forms because the quantum dot light emitting diode can have multiple forms, and the quantum dot light emitting diode has two kinds of structures: a positive configuration and an inverted configuration. The structure of the first quantum dot light emitting diode in this embodiment is the same as that of the second quantum dot light emitting diode, and when the structure of the first quantum dot light emitting diode is an upright structure, the structure of the second quantum dot light emitting diode is also an upright structure; when the structure of the first quantum dot light-emitting diode is an inverted structure, the structure of the second quantum dot light-emitting diode is also an inverted structure.
The working principle of the red and green sub-pixel point unit of this embodiment may be as follows: the second electrode is connected with a TFT thin film transistor as a driving electrode,
if the first quantum dot light-emitting diode and the second quantum dot light-emitting diode are both in a positive structure, when the second electrode is connected with the negative voltage, the first electrode and the third electrode are connected with the positive voltage and are both conducted with the second electrode, the first quantum dot light-emitting diode emits light, and the second quantum dot light-emitting diode does not emit light; when the second electrode is connected with a positive voltage, the first electrode and the third electrode are connected with a negative voltage and are both conducted with the second electrode, the first quantum dot light-emitting diode does not emit light, and the second quantum dot light-emitting diode emits light.
If the first quantum dot light-emitting diode and the second quantum dot light-emitting diode are both of inverted structures, when the second electrode is connected with the negative voltage, the first electrode and the third electrode are connected with the positive voltage and are both conducted with the second electrode, the first quantum dot light-emitting diode does not emit light, and the second quantum dot light-emitting diode emits light; when the second electrode is connected with a positive voltage, the first electrode and the third electrode are connected with a negative voltage and are both conducted with the second electrode, the first quantum dot light-emitting diode emits light, and the second quantum dot light-emitting diode does not emit light.
If the second electrode is connected with alternating current and the first electrode and the third electrode are both conducted with the second electrode, the first quantum dot light-emitting diode and the second quantum dot light-emitting diode alternately emit light without mutual influence.
In this embodiment, when the red and green sub-pixel units are of a top emission structure, that is, when light emitted by the red and green sub-pixel units is emitted from the third electrode, the first quantum dot light emitting layer emits red light, and the second quantum dot light emitting layer emits green light. Therefore, when red light emitted by the first quantum dot light emitting layer passes through the second quantum dot light emitting layer, the second quantum dot light emitting layer cannot be excited to emit green light, and the purity of light emitted by the quantum dot light emitting device can be ensured.
In this embodiment, when the red and green subpixel unit is of a bottom emission structure, that is, when light emitted by the red and green subpixel unit is emitted from the first electrode, the second quantum dot light emitting layer emits red light, and the first quantum dot light emitting layer emits green light. Therefore, when red light emitted by the second quantum dot light emitting layer passes through the first quantum dot light emitting layer, the first quantum dot light emitting layer cannot be excited to emit green light, and the purity of light emitted by the quantum dot light emitting device can be ensured.
When the red-green sub-pixel point unit is of a top emission structure, the first electrode is a total reflection electrode, the second electrode is a transparent electrode or a semitransparent electrode, and the third electrode is a transparent electrode. In one embodiment, the second electrode is a translucent electrode. When the semitransparent electrode is used, a strong microcavity structure is formed between the semitransparent electrode and the transparent electrode, so that the luminous efficiency of the second quantum dot luminous layer between the semitransparent electrode and the transparent electrode is improved; in addition, the semi-transparent electrode can isolate the two quantum dot light emitting layers to a certain degree, and the phenomenon that light with short wavelength excites quantum dots with longer light emitting wavelength in the other quantum dot light emitting layer is reduced. Therefore, the second electrode adopts the translucent electrode, so that the luminous efficiency of the quantum dot light-emitting device can be improved, the monochromaticity of emergent light is also improved, and the application range of the light-emitting device is wider.
When the red and green sub-pixel point unit is of a bottom emission structure, the first electrode is a transparent electrode, the second electrode is a transparent electrode or a semitransparent electrode, and the third electrode is a total reflection electrode. In one embodiment, the second electrode is a translucent electrode. When the semitransparent electrode is used, a strong microcavity structure is formed between the semitransparent electrode and the transparent electrode, so that the luminous efficiency of the second quantum dot luminous layer between the semitransparent electrode and the transparent electrode is improved; in addition, the semi-transparent electrode can isolate the two quantum dot light emitting layers to a certain degree, and the phenomenon that light with short wavelength excites quantum dots with longer light emitting wavelength in the other quantum dot light emitting layer is reduced. Therefore, the second electrode adopts the translucent electrode, so that the luminous efficiency of the quantum dot light-emitting device can be improved, the monochromaticity of emergent light is also improved, and the application range of the light-emitting device is wider.
The total reflection electrode means an electrode capable of reflecting all light, the semi-transparent electrode means an electrode capable of reflecting part of light and transmitting part of light, and the transparent electrode means an electrode capable of transmitting all light.
In one embodiment, the material of the total reflection electrode is selected from one of metals such as Al, Ag-based alloys (e.g., Mg and Ag alloys, etc.), and alloy materials thereof, but is not limited thereto. In the embodiment of the present invention, ITO electrodes (transparent electrodes), such as ITO/Ag/ITO, ITO/Ag-based alloy/ITO, may be further disposed on two sides of the total reflection electrode to reduce the work function of the electrode, which is beneficial to charge injection.
In one embodiment, the material of the translucent electrode is selected from one of metals such as Al, Ag-based alloys (e.g., Mg and Ag alloys, etc.), and alloy materials thereof, but is not limited thereto. In the embodiment of the present invention, IZO electrodes (transparent electrodes) such as IZO/Ag/IZO and Ag/IZO may be further disposed on two sides or one side of the translucent electrode to reduce the work function of the electrode, which is favorable for injecting charges.
In one embodiment, the material of the transparent electrode may be selected from one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), indium-doped zinc oxide (IZO), aluminum-doped zinc oxide (AZO), and the like, but is not limited thereto.
It should be noted that, the range of materials for the total reflection electrode and the translucent electrode is the same, and specifically, the same or different materials in the same range can be selected. By controlling the thickness of the electrode layer, the layer can be made to have a total reflection or semi-transparent function. When the thickness of an electrode layer made of metal or metal alloy material is more than 80nm, the electrode layer has a total reflection function; when the thickness of the electrode layer made of metal or metal alloy material is 10-30nm, the electrode layer has a semitransparent function. In one embodiment, the thickness of the total reflection electrode is 80-200nm, and the thickness of the semi-transparent electrode is 10-30 nm.
In an embodiment, when the first quantum dot light emitting diode and the second quantum dot light emitting diode are both in a forward structure, the red and green sub-pixel unit further includes:
a first hole injection layer disposed between the first electrode and the first quantum dot light emitting layer;
a first hole transport layer disposed between the first hole injection layer and the first quantum dot light emitting layer;
a first electron transport layer disposed between the second electrode and the first quantum dot light emitting layer;
a second hole injection layer disposed between the second electrode and the second quantum dot light emitting layer;
a second hole transport layer disposed between the second hole injection layer and the second quantum dot light emitting layer;
a second electron transport layer disposed between the second quantum dot light emitting layer and a third electrode.
In an embodiment, when the first quantum dot light emitting diode and the second quantum dot light emitting diode are both of an inverted structure, the red and green sub-pixel unit further includes:
a first electron transport layer disposed between the first electrode and the first quantum dot light emitting layer;
a first hole transport layer disposed between the first quantum dot light emitting layer and the second electrode;
a first hole injection layer disposed between the first hole transport layer and the second electrode;
a second electron transport layer disposed between the second electrode and the second quantum dot light emitting layer;
a second hole transport layer disposed between the second quantum dot light emitting layer and the third electrode;
a third hole injection layer disposed between the second hole transport layer and the third electrode.
In one embodiment, the substrate may be a rigid substrate, such as glass, or a flexible substrate, such as one of PET or PI.
In one embodiment, the materials of the first and second hole injection layers may be independently selected from the group consisting of PEODT: PSS, MoO3、WoO3、NiO、HATCN、CuO、V2O5And CuS, and the like.
In one embodiment, the materials of the first and second hole transport layers may be independently selected from TFB, PVK, Poly-TBP, Poly-TPD, NPB, TCTA, TAPC, CBP, PEODT: PSS, MoO3、WoO3、NiO、CuO、V2O5And CuS, and the like.
In one embodiment, the materials of the first and second electron transport layers may be independently selected from ZnO, ZrO, TiO2One or more of Alq3, TAZ, TPBI, PBD, BCP, Bphen, etc.
In one embodiment, the material of the first quantum dot light emitting layer and the second quantum dot light emitting layer may be selected from one or more of group II-VI compounds, group II-V compounds, group IV-VI compounds, group I-III-VI compounds, group I-II-IV-VI compounds, and the like.
In some embodiments, the blue subpixel unit 20 includes a fourth electrode, a third quantum dot light emitting layer, and a fifth electrode, which are sequentially stacked, and the fourth electrode 21 or the fifth electrode 22 is connected to a TFT thin film transistor. In this embodiment, the blue sub-pixel unit emits blue light under the driving of the TFT thin film transistor.
In this embodiment, the first quantum dot light emitting diode and the second quantum dot light emitting diode which emit different colors of light are integrated into one red-green sub-pixel unit, and the integrated red-green sub-pixel unit can control the first quantum dot light emitting diode and the second quantum dot light emitting diode to emit red light or green light independently according to needs, and can also control the first quantum dot light emitting diode and the second quantum dot light emitting diode to alternately emit red light and green light according to needs, and the red light and the green light can be combined with blue light emitted by the blue sub-pixel unit to form various colors of light. According to the embodiment, the single pixel point structure is reduced from the traditional RGB three-sub-pixel unit composition to the two-sub-pixel unit composition, the area of the single pixel point structure is reduced, and the resolution of the printing display device is further improved. The display device provided by the embodiment has higher resolution, simplifies the number of driving electrodes and reduces circuit loss.
Taking the red and green sub-pixel unit with the front-located structure provided in this embodiment as an example, taking the second electrode 12 as a driving electrode, if a negative voltage is applied to the driving electrode, and a positive voltage is applied to the first electrode and the third electrode and both are conducted with the driving electrode, then the hole and the electron at this time are combined in the first quantum dot light-emitting layer and excite the first quantum dot light-emitting layer to emit light, and at this time, the second quantum dot light-emitting layer is not excited to emit light; if a positive voltage is added on the driving electrode, a negative voltage is added on the first electrode and the third electrode, and the first electrode and the third electrode are both conducted with the driving electrode, the hole and the electron at the moment are compounded in the second quantum dot light-emitting layer and excite the second quantum dot light-emitting layer to emit light, and the first quantum dot light-emitting layer at the moment is not excited to emit light; if an alternating current voltage is applied to the driving electrode, the first quantum dot light-emitting layer and the second quantum dot light-emitting layer are alternately excited by excitons to realize alternate light emission, and the relative intensity of two different colors of light emitted by the first quantum dot light-emitting layer and the second quantum dot light-emitting layer can be adjusted by adjusting the relative proportion of the alternating current voltage, so that various colors of light formed by combining the two different colors can be emitted. In the embodiment, two sub-pixel units emitting different colors are combined into one sub-pixel unit, so that the structure and the preparation process of the display device are simplified, the area of the display device is reduced, the resolution of the display device is improved, and the application range of the display device is wider.
In some embodiments, there is also provided a method of manufacturing a display device, comprising the steps of:
preparing bottom electrodes distributed at intervals on a substrate;
preparing pixel point banks between adjacent bottom electrodes, and forming a plurality of adjacent pixel point cavities;
preparing red and green sub-pixel units and blue sub-pixel units in two adjacent pixel point cavities respectively, wherein the red and green sub-pixel units comprise a first electrode, a first quantum dot light-emitting layer, a second electrode, a second quantum dot light-emitting layer and a third electrode which are sequentially stacked; the blue sub-pixel unit comprises a fourth electrode, a third quantum dot light-emitting layer and a fifth electrode which are sequentially stacked.
The red and green sub-pixel unit 10 prepared in this embodiment is formed by combining quantum dot light emitting diodes with two emission wavelengths: the LED comprises a first quantum dot light-emitting diode (composed of a first electrode, a first quantum dot light-emitting layer and a second electrode) and a second quantum dot light-emitting diode (composed of a third electrode, a second quantum dot light-emitting layer and a second electrode), wherein the first quantum dot light-emitting diode and the second quantum dot light-emitting diode are combined together through a common second electrode, one of the light-emitting wavelength of the first quantum dot light-emitting layer and the light-emitting wavelength of the second quantum dot light-emitting layer can emit red light, and the other can emit green light.
In the embodiment, the quantum dot light-emitting diodes with two colors are combined into a red-green sub pixel point unit structure, so that the number of the quantum dot light-emitting diodes in a single pixel point structure is reduced, the area of the single pixel point structure is reduced, and the resolution of a printing display device is improved. The display device provided by the embodiment has higher resolution, simplifies the number of driving electrodes and reduces circuit loss.
In this embodiment, the preparation method of each layer may be a chemical method or a physical method, wherein the chemical method includes, but is not limited to, one or more of a chemical vapor deposition method, a continuous ion layer adsorption and reaction method, an anodic oxidation method, an electrolytic deposition method, and a coprecipitation method; the physical method includes, but is not limited to, one or more of solution method (such as spin coating, printing, knife coating, dip-coating, dipping, spraying, roll coating, casting, slit coating, or bar coating), evaporation method (such as thermal evaporation, electron beam evaporation, magnetron sputtering, or multi-arc ion plating), deposition method (such as physical vapor deposition, atomic layer deposition, pulsed laser deposition, etc.).
The following further explains a method for manufacturing a display device of the present invention by way of specific examples:
example 1
A preparation method of a display device comprises the following specific steps:
01. sputtering ITO/Ag/ITO distributed at intervals on a substrate to be used as a bottom electrode;
02. preparing pixel point banks between adjacent bottom electrodes, and forming a plurality of adjacent pixel point cavities;
03. printing a hole injection layer in one pixel point cavity, wherein the hole injection layer is made of MCC (MCC) and has the thickness of 30 nm;
04. printing a hole transport layer on the hole injection layer, wherein the material of the hole transport layer is Nissan and the thickness of the hole transport layer is 50 nm;
05. printing a red light quantum dot light-emitting layer on the hole transport layer, wherein the thickness of the red light quantum dot light-emitting layer is 15 nm;
06. printing an electron transport layer on the red light quantum dot light-emitting layer, wherein the electron transport layer is made of MZO (Mg-doped zinc oxide) and has the thickness of 80 nm;
07. sputtering Mg, namely Ag/ITO (indium tin oxide) as a second electrode on the electron transmission layer, wherein the thickness of the Mg, namely Ag, is 30nm, and the thickness of the ITO is 100 nm;
08. printing a hole injection layer on the second electrode, wherein the hole injection layer is made of MCC and has the thickness of 25 nm;
09. printing a hole transport layer on the hole injection layer, wherein the material of the hole transport layer is Nissan and the thickness of the hole transport layer is 60 nm;
10. printing a green light quantum dot light-emitting layer with the thickness of 10nm on the hole transport layer;
11. printing an electron transport layer on the green light quantum dot light-emitting layer, wherein the electron transport layer is made of MZO (Mg-doped zinc oxide) and has the thickness of 40 nm;
12. and sputtering IZO as a third electrode on the electron transport layer, wherein the thickness of the IZO is 100 nm.
13. Printing a hole injection layer on the other pixel point cavity (blue sub-pixel point unit), wherein the hole injection layer is made of MCC (MCC) and has the thickness of 30 nm;
14. printing a hole transport layer on the hole injection layer, wherein the material of the hole transport layer is Nissan and the thickness of the hole transport layer is 50 nm;
15. printing a blue quantum dot light-emitting layer with the thickness of 30nm on the hole transport layer;
16. printing an electron transport layer on the blue quantum dot light-emitting layer, wherein the electron transport layer is made of MZO (Mg-doped zinc oxide) and has the thickness of 50 nm;
17. and sputtering IZO as a fifth electrode on the electron transport layer, wherein the thickness of the IZO is 100 nm.
In the above embodiment, the green light quantum dot light-emitting layer is disposed at a position far away from the total reflection bottom electrode, so that the ratio of exciting the red light quantum dot light-emitting layer can be reduced. Because the second electrode is a semitransparent electrode, the proportion of green light which passes through the second electrode and reaches the red light quantum dot light-emitting layer is smaller, and the monochromaticity of the emitted green light is higher. In addition, the red light quantum dot light-emitting layer forms a microcavity structure, so that the light extraction efficiency of red light is higher. The color of light emitted by the red and green sub-pixel points is controlled by controlling the positive and negative of the applied voltage, and the mutual interference of the light emitted between two color quantum dots is greatly reduced by the design of the stacking sequence of the strong microcavity structure, the semi-reflective electrode and the quantum dots, so that the light emitting efficiency is improved, and the color purity and brightness are ensured.
Example 2
A preparation method of a display device comprises the following specific steps:
01. sputtering ITO distributed at intervals on a substrate to be used as a bottom electrode;
02. preparing pixel point banks between adjacent bottom electrodes, and forming a plurality of adjacent pixel point cavities;
03. printing a hole injection layer in one pixel point cavity, wherein the hole injection layer is made of MCC (MCC) and has the thickness of 30 nm;
04. printing a hole transport layer on the hole injection layer, wherein the hole transport layer is made of TFB and has the thickness of 50 nm;
05. printing a red light quantum dot light-emitting layer on the hole transport layer, wherein the thickness of the red light quantum dot light-emitting layer is 15 nm;
06. printing an electron transport layer on the red light quantum dot light-emitting layer, wherein the electron transport layer is made of TiO and has the thickness of 80 nm;
07. sputtering Ag/ITO on the electron transmission layer to form a second electrode, wherein the thickness of Ag is 30nm, and the thickness of ITO is 100 nm;
08. printing a hole injection layer on the second electrode, wherein the hole injection layer is made of MCC and has the thickness of 25 nm;
09. printing a hole transport layer on the hole injection layer, wherein the hole transport layer is made of TFB and has the thickness of 60 nm;
10. printing a green light quantum dot light-emitting layer with the thickness of 10nm on the hole transport layer;
11. printing an electron transport layer on the green light quantum dot light-emitting layer, wherein the electron transport layer is made of TiO and has the thickness of 40 nm;
12. and sputtering Ag on the electron transmission layer to form a third electrode, wherein the thickness of the Ag is 100 nm.
13. Printing a hole injection layer on the other pixel point cavity (blue sub-pixel point unit), wherein the hole injection layer is made of MCC (MCC) and has the thickness of 30 nm;
14. printing a hole transport layer on the hole injection layer, wherein the hole transport layer is made of TFB and has the thickness of 50 nm;
15. printing a blue quantum dot light-emitting layer with the thickness of 30nm on the hole transport layer;
16. printing an electron transport layer on the blue quantum dot light-emitting layer, wherein the electron transport layer is made of TiO and has the thickness of 50 nm;
17. and sputtering Ag on the electron transport layer to form a fifth electrode, wherein the thickness of the Ag is 100 nm.
In conclusion, the red sub-pixel units and the green sub-pixel units are integrated into one pixel unit, so that the number of the sub-pixel units in a single pixel structure is reduced (from 3 to 2), the area of the single pixel structure is reduced, and the resolution of the printing display device is improved. The display device provided by the invention not only has higher resolution, but also simplifies the number of driving electrodes and reduces the circuit loss.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.
Claims (9)
1. A display device is characterized by comprising a plurality of pixel point structures, wherein each pixel point structure comprises a red-green sub pixel point unit and a blue sub pixel point unit;
the red and green sub-pixel point unit comprises a first electrode, a first quantum dot light-emitting layer, a second electrode, a second quantum dot light-emitting layer and a third electrode which are sequentially stacked,
the first quantum dot light emitting layer and the second quantum dot light emitting layer can emit light individually or alternately,
one of the first quantum dot light emitting layer and the second quantum dot light emitting layer can emit red light, the other can emit green light,
the second electrode is connected with a TFT thin film transistor,
the first electrode, the first quantum dot light emitting layer and the second electrode form one of an upright type light emitting device and an inverted type light emitting device, and the second electrode, the second quantum dot light emitting layer and the third electrode form the same one of the upright type light emitting device and the inverted type light emitting device.
2. The display device according to claim 1, wherein in a light emission direction of the red-green sub-pixel unit, a wavelength of light which can be emitted by a quantum dot light-emitting layer located on a downstream side in the light emission direction, of the first quantum dot light-emitting layer and the second quantum dot light-emitting layer, is longer than a wavelength of light which can be emitted by a quantum dot light-emitting layer located on an upstream side.
3. The display device according to claim 1, wherein when the second electrode is connected to a negative voltage, and the first electrode and the third electrode are connected to a positive voltage and are both in conduction with the second electrode, one of the first quantum dot light emitting layer and the second quantum dot light emitting layer emits light;
the second electrode is connected with high voltage, and when the first electrode and the third electrode are connected with low voltage and are both conducted with the second electrode, one of the first quantum dot light-emitting layer and the second quantum dot light-emitting layer emits light;
when the second electrode is connected with alternating current and the first electrode and the third electrode are both communicated with the second electrode, the first quantum dot light-emitting layer and the second quantum dot light-emitting layer alternately emit light.
4. The display device according to claim 1, wherein in a light emitting direction of the red and green sub-pixel unit, an electrode on an upstream side in the light emitting direction of the first electrode and the third electrode is a total reflection electrode, an electrode on a downstream side is a transparent electrode, and the second electrode is a transparent electrode or a semitransparent electrode.
5. The display device according to claim 4, wherein the second electrode is a translucent electrode.
6. A display device as claimed in claim 4, characterized in that one or both sides of the total-reflective and/or semi-transparent electrode are provided with an additional transparent electrode for lowering the work function.
7. The QD light emitting device according to any of claims 4 to 6, wherein the material of the total reflection electrode is selected from one or more of Al, Ag and alloys containing Al, Ag or Ag,
the material of the translucent electrode is selected from one or more of Al, Ag and an alloy containing Al, Ag or Ag,
the material of the transparent electrode is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, indium-doped zinc oxide and aluminum-doped zinc oxide.
8. The display device according to claim 1, wherein the blue sub-pixel unit comprises a fourth electrode, a third quantum dot light-emitting layer and a fifth electrode which are sequentially stacked, and the fourth electrode or the fifth electrode is connected with a TFT thin film transistor.
9. The display device according to claim 1, wherein the display device is a mobile phone, a computer, or a television.
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| CN202011616642.6A CN114695689A (en) | 2020-12-30 | 2020-12-30 | Display device with a light-shielding layer |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116456776A (en) * | 2023-04-27 | 2023-07-18 | 惠科股份有限公司 | Array substrate, display panel and display device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116456776A (en) * | 2023-04-27 | 2023-07-18 | 惠科股份有限公司 | Array substrate, display panel and display device |
| CN116456776B (en) * | 2023-04-27 | 2024-05-17 | 惠科股份有限公司 | Array substrate, display panel and display device |
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