Display panel

Abstract

The present invention provides a display panel, which includes a driving circuit layer and a micro-LED chip and a quantum dot light-emitting device located above the driving circuit layer; the micro-LED chip includes a first anode and a first cathode located in the same layer; the quantum dot light-emitting device includes a second anode, a quantum dot light-emitting material layer located above the second anode, and a second cathode located above the quantum dot light-emitting material layer, the second cathode being electrically connected to the first cathode; and a spacer layer for supporting the micro-LED chip and the quantum dot light-emitting device; wherein the spacer layer is provided with an undercut structure at a position corresponding to the position between the first anode and the first cathode to spatially disconnect the first anode from the first cathode; this technical solution can completely solve the problem of the micro-LED chip and the quantum dot light-emitting device sharing a cathode wiring and the problem of the micro-LED chip short-circuiting, thereby improving the stability of the driving signal transmission of the display panel.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a display panel. Background Art

[0002] Micro-LED technology is a miniaturized and matrixed LED technology. It refers to the integration of a high-density, tiny LED array on a single chip, reducing the distance between pixels from millimeters to microns or even nanometers. Specifically, multiple Micro-LED chips are arranged on an array substrate. Due to the large number of Micro-LED chips arranged on the array substrate, the pins of each Micro-LED chip are connected to the pads on the array substrate using surface spot welding and can be individually controlled. Therefore, Micro-LED display panels have the advantages of higher brightness, dynamic adjustment, and lower power consumption.

[0003] However, in Micro LED displays, the efficiency and stability of red and blue Micro LED chips are far inferior to those of red and green quantum dot light-emitting devices. This has led to the proposal of a hybrid display of Micro-LED chips and quantum dot light-emitting devices. Conventional Micro-LED chips are flip-chip LED chips, while quantum dot light-emitting devices are vertical. On the same TFT backplane, a planar Micro-LED chip and a vertical quantum dot light-emitting device are transferred and then a common cathode is made. Directly vapor-depositing a metal cathode on the entire surface will cause a short circuit between the cathode and the anode of the Micro LED, resulting in device failure. A method must be found to isolate the chip's anode and common cathode. Using a fine vapor deposition mask to pattern the cathode is expensive and has limited precision.

[0004] Therefore, a new type of display panel is needed to solve the above-mentioned technical problems. When preparing Micro LED chips and quantum dot light-emitting devices on the same TFT backplane, directly evaporating the metal cathode on the entire surface will cause the cathode and Micro LED anode to short-circuit, resulting in device failure. It is necessary to find a way to isolate the anode and common cathode of the chip. If a fine evaporation mask is used to pattern the cathode, the cost is high and the precision is limited. Summary of the Invention

[0005] The present invention provides a display panel that can solve the technical problems in the prior art of preparing Micro LED chips and quantum dot light-emitting devices on the same TFT backplane. Directly vapor-depositing a metal cathode on the entire surface will cause the cathode to short-circuit the Micro LED anode, resulting in device failure. It is necessary to find a way to isolate the chip's anode and common cathode. If a fine vapor deposition mask is used to pattern the cathode, the cost is high and the precision is limited.

[0006] The technical solutions provided by the present invention are as follows:

[0007] An embodiment of the present invention provides a display panel, comprising a driving circuit layer, and a micro LED chip and a quantum dot light-emitting device located above the driving circuit layer, wherein the quantum dot light-emitting device is located on one side of the micro LED chip;

[0008] The micro LED chip includes a first anode and a first cathode located in the same layer, and the first anode and the first cathode are insulated;

[0009] The quantum dot light emitting device includes a second anode, a quantum dot light emitting material layer located on the second anode, and a second cathode located on the quantum dot light emitting material layer, wherein the second cathode is electrically connected to the first cathode; and

[0010] A cushioning layer, used for supporting the micro LED chip and the quantum dot light-emitting device;

[0011] The raised layer is provided with an undercut structure at a position corresponding to the position between the first anode and the first cathode, so as to spatially disconnect the first anode from the first cathode.

[0012] According to a preferred embodiment of the present invention, a planarization layer is provided on the surface of the driving circuit layer, and the padding layer is provided on the planarization layer. The padding layer includes a first sub-padding layer and a second sub-padding layer that are spaced apart. The first sub-padding layer is located directly below the first anode, and the second sub-padding layer is located directly below the first cathode and the second anode.

[0013] The undercut structure includes a first hollow structure and a second hollow structure, the first hollow structure is located between the first sub-elevation layer and the second sub-elevation layer, and the second hollow structure is located on a side of the first sub-elevation layer away from the second sub-elevation layer.

[0014] According to a preferred embodiment of the present invention, the quantum dot light-emitting device further includes a pixel definition layer located above the second sub-layer, the second cathode is adhered to the surface of the pixel definition layer, extends to the surface of the second sub-layer, and is electrically connected to the first cathode.

[0015] According to a preferred embodiment of the present invention, the second cathode is formed by full-surface evaporation, and an extended portion thereof fills the second hollow structure but does not contact the first anode.

[0016] According to a preferred embodiment of the present invention, the thickness of the first sub-layer is greater than the thickness of the second cathode layer.

[0017] According to a preferred embodiment of the present invention, the material of the padding layer is one of silicon nitride, silicon oxide, or silicon oxynitride, or a combination of more than one of these materials.

[0018] According to a preferred embodiment of the present invention, a pixel unit of the display panel includes a micro LED chip and two quantum dot light-emitting devices, one micro LED chip is a blue light Micro-LED chip, and the two quantum dot light-emitting devices are a red quantum dot light-emitting device and a green quantum dot light-emitting device.

[0019] According to a preferred embodiment of the present invention, the p-electrode of the micro LED chip is electrically connected to the first anode, and the n-electrode of the micro LED chip is electrically connected to the first cathode.

[0020] According to a preferred embodiment of the present invention, two quantum dot light-emitting devices share the second cathode, and the second cathode is a transparent ITO electrode.

[0021] According to a preferred embodiment of the present invention, the first anode, the first cathode and the second anode are arranged in the same layer, and the material of the first anode, the first cathode and the second anode is one of copper, molybdenum, titanium or aluminum.

[0022] Beneficial effects of the present invention: An embodiment of the present invention provides a display panel, which includes a driving circuit layer and a micro LED chip and a quantum dot light-emitting device located above the driving circuit layer, the quantum dot light-emitting device is located on one side of the micro LED chip; the micro LED chip includes a first anode and a first cathode located in the same layer, and the first anode is insulated from the first cathode; the quantum dot light-emitting device includes a second anode, a quantum dot light-emitting material layer located above the second anode, and a second cathode located above the quantum dot light-emitting material layer, the second cathode is electrically connected to the first cathode; and a padding layer for carrying the micro LED chip and the quantum dot light-emitting device; wherein the padding layer is provided with an undercut structure at a position corresponding to the position between the first anode and the first cathode, so as to spatially disconnect the first anode from the first cathode; this technical solution can completely solve the problem of the micro LED chip and the quantum dot light-emitting device sharing a cathode wiring and the short circuit problem of the micro LED chip, thereby improving the driving signal transmission stability of the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 and Figure 2 Schematic diagram of the film layer structure of a display panel in the prior art.

[0025] Figure 3 A schematic diagram of a film layer structure of a display panel is provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following descriptions of the various embodiments are made with reference to the accompanying drawings to illustrate specific embodiments in which the present invention may be implemented. Directional terms used in the present invention, such as [up], [down], [front], [back], [left], [right], [inside], [outside], and [side], are merely referenced to the directions in the accompanying drawings. Therefore, the directional terms used are intended to illustrate and facilitate understanding of the present invention, and are not intended to limit the present invention. In the drawings, units with similar structures are denoted by the same reference numerals. Dotted lines in the drawings indicate elements that do not exist in the structure and are merely used to illustrate the shape and position of the structure.

[0027] like Figure 1 As shown, the display panel 10 in the prior art includes a substrate 11, a planarization layer 12 is prepared on the surface of the substrate 11, a Micro LED chip 15, a first quantum dot light-emitting device and a second quantum dot light-emitting device are arranged on the planarization layer 12, a first anode 13 and a first cathode 14 are arranged between the planarization layer 12 and the Micro LED chip 15, and a P electrode 151 of the Micro LED chip 15 is electrically connected to the first anode 13. The n-electrode 152 of the LED chip 15 is electrically connected to the first cathode 14; the first quantum dot light-emitting device includes a second anode 161, a quantum dot light-emitting material layer 162 located on the second anode 161, and a second cathode 163 located on the quantum dot light-emitting material layer 162; the second quantum dot light-emitting device includes a second anode 171, a quantum dot light-emitting material layer 172 located on the second anode 171, and a second cathode 163 located on the quantum dot light-emitting material layer 172; the second cathode 163 is electrically connected to the first cathode 14, sharing a cathode trace; due to the direct vapor deposition of the metal cathode on the entire surface, the extended second cathode 163 is electrically connected to the first anode 13 (left side in Figure 1), causing the cathode Micro LED anode to short-circuit, resulting in failure of the Micro LED chip 15, the first quantum dot light-emitting device, and the second quantum dot light-emitting device.

[0028] like Figure 2 As shown, the inventors Figure 1 On the basis of this, further improvements were made. The first anode 13 and the first cathode 14 were arranged in the upper and lower layers, and then the second cathode 163 was evaporated, so that the first anode 13 was also shared with the second cathode 163. If a fine evaporation mask was used to pattern the second cathode 163 to disconnect the first anode 13 from the first anode 13, there would be technical problems of high cost and limited precision.

[0029] In the above two embodiments, Micro LED chips and quantum dot light-emitting devices are prepared on the same TFT backplane. Directly vapor-depositing a metal cathode on the entire surface will cause a short circuit between the cathode and the anode of the Micro LED chip, resulting in device failure. It is necessary to find a way to isolate the anode and common cathode of the chip. If a fine vapor deposition mask is used to pattern the cathode, the cost is high and the precision is limited. Therefore, the inventors further improved the structure of the display panel to solve the defects in the above embodiments.

[0030] An embodiment of the present invention provides a display panel, which includes a driving circuit layer and a micro LED chip and a quantum dot light-emitting device located above the driving circuit layer, wherein the quantum dot light-emitting device is located on one side of the micro LED chip; the micro LED chip includes a first anode and a first cathode located in the same layer, and the first anode is insulated from the first cathode; the quantum dot light-emitting device includes a second anode, a quantum dot light-emitting material layer located above the second anode, and a second cathode located above the quantum dot light-emitting material layer, and the second cathode is electrically connected to the first cathode; and a padding layer for supporting the micro LED chip and the quantum dot light-emitting device; wherein the padding layer is provided with an undercut structure at a position corresponding to the position between the first anode and the first cathode, so as to spatially disconnect the first anode from the first cathode; this technical solution can completely solve the problem of the micro LED chip and the quantum dot light-emitting device sharing a cathode wiring and the short circuit problem of the micro LED chip, thereby improving the stability of the driving signal transmission of the display panel.

[0031] A planarization layer is provided on the surface of the driving circuit layer, and a padding layer is provided on the planarization layer, the padding layer including a first sub-padding layer and a second sub-padding layer arranged at intervals, the first sub-padding layer being located directly below the first anode, and the second sub-padding layer being located directly below the first cathode and the second anode; wherein, the undercut structure includes a first hollow structure and a second hollow structure, the first hollow structure being located between the first sub-padding layer and the second sub-padding layer, so that the first anode and the first cathode are disconnected and not in contact; in addition, the second cathode is formed by full-surface vapor deposition, and its extended part fills the second hollow structure, but is not in contact with the first anode, that is, the extended part of the second cathode is not electrically connected to the first anode, thereby spatially disconnecting the first anode and the first cathode, and preventing the two from being electrically connected, thereby avoiding a short circuit and ensuring that the Micro LED chip and quantum dot light-emitting device prepared on the same TFT backplane can display normally.

[0032] Specifically, if Figure 3As shown, an embodiment of the present invention provides a schematic diagram of the film layer structure of a display panel 20. A pixel unit of the display panel includes a micro LED chip and two quantum dot light-emitting devices. The micro LED chip is preferably a blue Micro-LED chip, and can also be a Mini-LED chip; the two quantum dot light-emitting devices are respectively a red quantum dot light-emitting device and a green quantum dot light-emitting device. The display panel includes a driving circuit layer 21 and a micro LED chip 26, a green quantum dot light-emitting device 27, and a red quantum dot light-emitting device 28 located above the driving circuit layer 21. The micro LED chip 26 is preferably a blue Micro-LED chip. The green quantum dot light-emitting device 27 and the red quantum dot light-emitting device 28 share a second cathode 273. The green quantum dot light-emitting device 27 and the red quantum dot light-emitting device 28 are located on one side of the micro LED chip 26.

[0033] Among them, the micro LED chip 26 includes a first anode 24 and a first cathode 25 located in the same layer, and the first anode 24 is insulated from the first cathode 25; the green quantum dot light-emitting device 27 includes a second anode 271, a quantum dot light-emitting material layer 272 located on the second anode 271, and a second cathode 273 located on the quantum dot light-emitting material layer 272, and the second cathode 273 is electrically connected to the first cathode 25; the red quantum dot light-emitting device 28 includes a second anode 281, a quantum dot light-emitting material layer 282 located on the second anode 281, and a second cathode 273 located on the quantum dot light-emitting material layer 282.

[0034] The display panel 20 of this embodiment also includes a spacer layer 23 for supporting a micro-LED chip 26, a green quantum dot light-emitting device 27, and a red quantum dot light-emitting device 28. The spacer layer 23 has an undercut structure corresponding to the position between the first anode 24 and the first cathode 25 to spatially disconnect the first anode from the first cathode. A planarization layer 22 is provided on the surface of the driving circuit layer 21, and a spacer layer 23 is provided on the planarization layer 22. The spacer layer 23 includes a first sub-spacer layer 231 and a second sub-spacer layer 232, with the first sub-spacer layer 231 being located directly below the first anode 24, and the second sub-spacer layer 232 being located directly below the first cathode 25, the second anode 271, and the second anode 281. The material of the first sub-spacer layer 231 and the second sub-spacer layer 232 is one or a combination of silicon nitride, silicon oxide, or silicon oxynitride.

[0035] The undercut structure includes a first hollow structure 233 and a second hollow structure 234. The first hollow structure 233 is located between the first sub-shielding layer 231 and the second sub-shielding layer 232, thereby disconnecting the first anode 24 and the first cathode 25 from each other. Furthermore, the second cathode 273 is formed by full-surface vapor deposition, and its extended portion fills the second hollow structure 234 but does not contact the first anode 24. That is, the extended portion of the second cathode 273 is not electrically connected to the first anode 24. This spatially disconnects the first anode 24 and the first cathode 25, preventing electrical connection between the two and preventing a short circuit. This completely solves the problem of the micro-LED chip and quantum dot light-emitting device sharing a cathode trace and the problem of micro-LED chip short circuits, thereby improving the stability of the display panel's drive signal transmission and ensuring that the micro-LED chip 26 and the quantum dot light-emitting device prepared on the same TFT backplane can display normally. In this embodiment, the thickness of the first sub-shielding layer 231 is greater than the thickness of the second cathode layer 273.

[0036] The quantum dot light-emitting device also includes a pixel definition layer located above the second sub-raising layer 232. For example, a pixel definition layer 291 is arranged between the green quantum dot light-emitting device 27 and the micro LED chip 26, a pixel definition layer 292 is arranged between the green quantum dot light-emitting device 27 and the red quantum dot light-emitting device 28, and a pixel definition layer 293 is arranged on the side of the red quantum dot light-emitting device 28 away from the green quantum dot light-emitting device 27. The second cathode 273 is adhered to the surface of the pixel definition layer 291, extends to the surface of the second sub-raising layer 232, and is electrically connected to the first cathode 25.

[0037] The p-electrode 261 of the micro-LED chip 26 is electrically connected to the first anode 24, and the n-electrode 262 of the micro-LED chip 26 is electrically connected to the first cathode 25. The two quantum dot light-emitting devices share a first cathode 273, which is a transparent ITO electrode. The first anode 24, first cathode 25, second anode 271, and second anode 281 are arranged in the same layer and fabricated using the same photomask. They are made of the same metal material, which can be one or more of copper, molybdenum, titanium, or aluminum.

[0038] The second cathode 273 is prepared as a whole layer. Due to the existence of the first sub-layer 231, the first anode is disconnected from the second cathode 273 near the first anode 24 ( Figure 3The lower left corner of the display panel prevents short circuits between the first anode 24 and the second cathode 273. The quantum dot luminescent material layer comprises one or a combination of silicon quantum dots, germanium quantum dots, cadmium sulfide quantum dots, cadmium selenide quantum dots, cadmium telluride quantum dots, zinc selenide quantum dots, lead sulfide quantum dots, lead selenide quantum dots, indium phosphide quantum dots, and indium arsenide quantum dots. The light-emitting surface of the micro-LED chip is preferably flush with the light-emitting surface of the quantum dot light-emitting device, ensuring that the display screen in all display areas of the display panel is at the same height, avoiding the problem of floating display screens. The cross-sectional shape of the micro-LED chip is an inverted trapezoid, which helps to increase the light-emitting area and viewing angle of the micro-LED chip.

[0039] Specifically, the driver circuit layer 21 in this embodiment is a passive or active addressing driver circuit. The passive addressing driver circuit connects the anodes of pixels in each column of the array to the column scan lines, while simultaneously connecting the cathodes of pixels in each row to the row scan lines. When a particular Y-th column scan line and X-th row scan line are selected, the pixel at their intersection (X, Y) is illuminated. In this manner, the entire screen is scanned point by point at high speed to display the image. In the active addressing drive circuit, each pixel has its corresponding independent drive circuit, and the drive current is provided by the drive transistor. Generally, the active matrix drive circuit includes at least a dual-transistor and a single-capacitor circuit. At least two transistors are used in each pixel circuit to control the output current. T1 is a gate transistor used to control the on or off of the pixel circuit. T2 is a drive transistor that is connected to the voltage source and provides a stable current to the pixel within a frame. There is also a storage capacitor C1 in the circuit to store the data signal. When the scanning signal pulse of the pixel ends, the storage capacitor can still maintain the voltage of the gate of the drive transistor T2, thereby providing a continuous drive current to the pixel until the end of a frame.

[0040] The preparation method of the present invention is as follows: in the preparation process of the backplane of the hybrid display device of the Micro LED chip and the quantum dot light-emitting device, a planarization layer 22 is prepared on the driving circuit layer 21. After the planarization layer 21 is completed, a passivation layer is deposited, and then the first anode 21, the first cathode 25, and the second anode 271 and the second anode 281 of the quantum dot light-emitting device that are electrically connected to the micro LED chip 26 are made. By isotropically etching the passivation layer, the passivation layer is etched to form a first sub-pad layer 231 and a second sub-pad layer 232. The first sub-pad layer 231 and the second sub-pad layer 232 form the required pad layer 23. At the same time, an undercut structure is provided at the position between the first anode 24 and the first cathode 25 of the pad layer 23 to spatially disconnect the first anode 24 and the first cathode 25 to avoid short circuit. The undercut structure includes a first hollow structure 233 and a second hollow structure 234. After the transfer of the micro LED chip 26 and the printing of the quantum dot luminescent material layer 272 and the quantum dot luminescent material layer 282 of the quantum dot light-emitting device are completed, when the second cathode 273 is co-plated on the entire surface of the metal vapor deposition plate, the co-plated second cathode 273 is disconnected at the bottom cut structure position, and there is no overlap with the first anode 24 electrically connected to the micro LED chip 26. The co-plated second cathode 273 at other positions is connected to the first cathode 25 electrically connected to the micro LED chip 26 to form a hybrid display device.

[0041] In summary, although the present invention has been disclosed above with reference to preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A display panel, characterized in that: It includes a driving circuit layer and a micro LED chip and a quantum dot light-emitting device located on the driving circuit layer, wherein the quantum dot light-emitting device is located on one side of the micro LED chip; The micro LED chip includes a first anode and a first cathode located in the same layer, and the first anode and the first cathode are insulated; The quantum dot light emitting device includes a second anode, a quantum dot light emitting material layer located on the second anode, and a second cathode located on the quantum dot light emitting material layer, wherein the second cathode is electrically connected to the first cathode; and A cushioning layer, used for supporting the micro LED chip and the quantum dot light-emitting device; The raised layer is provided with an undercut structure at a position corresponding to the position between the first anode and the first cathode, and the extended portion of the second cathode is not electrically connected to the first anode, so as to spatially disconnect the first anode from the first cathode.

2. The display panel according to claim 1, wherein: A planarization layer is provided on the surface of the driving circuit layer, and the padding layer is provided on the planarization layer. The padding layer includes a first sub-padding layer and a second sub-padding layer that are spaced apart. The first sub-padding layer is located directly below the first anode, and the second sub-padding layer is located directly below the first cathode and the second anode. The undercut structure includes a first hollow structure and a second hollow structure, the first hollow structure is located between the first sub-elevation layer and the second sub-elevation layer, and the second hollow structure is located on a side of the first sub-elevation layer away from the second sub-elevation layer.

3. The display panel according to claim 2, wherein: The quantum dot light emitting device further includes a pixel definition layer located above the second sub-elevation layer. The second cathode is adhered to the surface of the pixel definition layer, extends to the surface of the second sub-elevation layer, and is electrically connected to the first cathode.

4. The display panel according to claim 2, wherein: The second cathode is formed by full-surface evaporation, and its extended portion fills the second hollow structure but does not contact the first anode.

5. The display panel according to claim 4, wherein: The thickness of the first sub-layer is greater than the thickness of the second cathode layer.

6. The display panel according to claim 1, wherein: The material of the padding layer is one of silicon nitride, silicon oxide or silicon oxynitride, or a combination of more than one of the materials.

7. The display panel according to claim 1, wherein: A pixel unit of the display panel includes a micro LED chip and two quantum dot light-emitting devices, one micro LED chip is a blue light Micro-LED chip, and the two quantum dot light-emitting devices are a red quantum dot light-emitting device and a green quantum dot light-emitting device.

8. The display panel according to claim 7, wherein: The p-electrode of the micro LED chip is electrically connected to the first anode, and the n-electrode of the micro LED chip is electrically connected to the first cathode.

9. The display panel according to claim 7, wherein: The two quantum dot light-emitting devices share the second cathode, and the second cathode is a transparent ITO electrode.

10. The display panel according to claim 1, wherein The first anode, the first cathode and the second anode are arranged in the same layer, and the material of the first anode, the first cathode and the second anode is one of copper, molybdenum, titanium or aluminum.

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