Display panel, method of manufacturing the same, and display device

Abstract

The present disclosure provides a display panel having a light-emitting layer, a transparent spacer layer on the light-emitting layer, and a wavelength conversion layer on the transparent spacer layer, wherein, according to the luminance change rate of the wavelength conversion unit of the adjacent pixel and the light path characteristic of the transparent spacer layer, by controlling the light intensity proportion reaching the wavelength conversion unit of the adjacent sub-pixel within a certain limit, at least part of the color mixing problem of the wavelength conversion type display panel is solved.

Description

Technical Field

[0001] This disclosure relates to the field of displays, and more specifically to a display panel, a method for manufacturing the same, and a display device. Background Technology

[0002] Organic light-emitting diode (OLED) displays have become the mainstream display technology, dominating the mobile display market and attracting significant interest from manufacturers in TV and other display applications. From the perspective of color display, OLED technology mainly falls into two categories. One type uses organic light-emitting materials that emit different colors of light (such as red, green, and blue light-emitting materials) to form sub-pixels of different colors, known as RGB. RGB has a high color gamut and has captured the small-to-medium-sized application market. However, it cannot be scaled up to a large area due to limitations in fine metal mask (FMM) technology. While inkjet-printed RGB OLEDs represent a potential technology for large-size OLEDs, the color gamut is not high enough due to limitations in the development of solution-based OLED materials. The other type uses monochrome OLEDs as backlight units combined with a color filter to achieve color display, known as backlight-color filter type. Since open-mask evaporation can be used for full-surface deposition, white backlight combined with a color filter is one of the mainstream technologies for large-size OLEDs. In white backlight-color filter technology, the color filter filters out wavelengths of light other than the desired colors from the white light. The color gamut of the color filter directly limits the color gamut range of large-size OLED products.

[0003] Technology has emerged that uses wavelength conversion elements to change the color of light emitted by a monochrome OLED to achieve color display. For example, a technology combining blue OLED with QD (quantum dot) has been proposed, using blue OLED as the light source and QD to convert blue light into red and green light to achieve color display, known as QD-OLED.

[0004] The development of display panels incorporating wavelength conversion elements still faces many practical technical challenges. There remains a need for improvement in display panels that include wavelength conversion elements, particularly QD conversion layers.

[0005] Overview

[0006] This disclosure provides a display panel, including:

[0007] The light-emitting layer on the substrate

[0008] The transparent spacer layer on the light-emitting layer, and

[0009] Wavelength conversion layer on the transparent spacer layer,

[0010] The display panel includes an array of sub-pixels, each sub-pixel comprising adjacent first and second sub-pixels. Each of the first and second sub-pixels includes a light-emitting unit in the light-emitting layer and a wavelength conversion unit in the wavelength conversion layer. The light-emitting unit and the wavelength conversion unit are stacked and separated by the transparent spacer layer.

[0011] The light-emitting units of the first sub-pixel and the second sub-pixel are separated by the first pixel defining layer in the light-emitting layer, and the top surface spacing is d2.

[0012] The wavelength conversion unit of the first sub-pixel is a first wavelength conversion unit and its brightness change rate for the light emitted by the light-emitting unit is ra; the wavelength conversion unit of the second sub-pixel is a second wavelength conversion unit and its brightness change rate for the light emitted by the light-emitting unit is rb; the wavelength conversion units of the first sub-pixel and the second sub-pixel are separated by a second pixel defining layer in the wavelength conversion layer.

[0013] In the direction from the first sub-pixel to the second sub-pixel, the displacement of the orthographic projection on the substrate relative to the top surface of the light-emitting unit of the second sub-pixel and the boundary of the first pixel defining layer between the light-emitting units of the first and second sub-pixels, and the displacement of the bottom surface of the second wavelength conversion unit and the boundary of the second pixel defining layer between the wavelength conversion units of the first and second sub-pixels, relative to the boundary of the first pixel defining layer between the light-emitting units of the second and second sub-pixels, is d42.

[0014] in,

[0015] Of the light incident from the top surface of the light-emitting unit onto the transparent spacer layer and reaching the top surface of the transparent spacer layer, the intensity percentage of light with an exit angle greater than α1 is less than x1%, where x1% = p1 × (ra / rb), and p1 ≤ 5%.

[0016] Wherein, when the emission angle of light originating from the bottom surface of the transparent spacer layer is α1, the length of the projection of the light path through the transparent spacer layer onto the substrate is less than or equal to d2+d42.

[0017] Optionally, p1 ≤ 2%.

[0018] Optionally, when the emission angle of light originating from the bottom surface of the transparent spacer is α1, the difference between the length of the projection of the light path through the transparent spacer onto the substrate and d2+d42 is less than or equal to 5μm.

[0019] Optionally, in the direction from the second sub-pixel to the first sub-pixel, the displacement of the orthographic projection on the substrate relative to the top surface of the first sub-pixel's light-emitting unit and the boundary of the first pixel defining layer between the first and second sub-pixels' light-emitting units, and the displacement of the bottom surface of the first wavelength conversion unit and the boundary of the second pixel defining layer between the first and second sub-pixels' wavelength conversion units, relative to the boundary of the first and second sub-pixels' light-emitting units', is d41.

[0020] in,

[0021] Of the light incident from the top surface of the light-emitting unit onto the transparent spacer layer and reaching the top surface of the transparent spacer layer, the intensity percentage of light with an exit angle greater than α2 is less than x2%, where x2% = p2 × (rb / ra), and p2 ≤ 5%.

[0022] Wherein, when the emission angle of light originating from the bottom surface of the transparent spacer layer is α2, the length of the projection of the light path through the transparent spacer layer onto the substrate is less than or equal to d2+d41.

[0023] Alternatively, p2 = p1.

[0024] Optionally, d41 = d42.

[0025] Optionally, |d41| ≤ 5μm, |d42| ≤ 5μm.

[0026] Optionally, the thickness of the transparent spacer layer is d1, and the transparent spacer layer comprises m sub-layers stacked from bottom to top, wherein the thickness and refractive index of the i-th sub-layer are L and L, respectively. i and n i i is from 1 to m.

[0027] All parameters satisfy:

[0028]

[0029] Where i is an integer from 1 to m, n i sinθ 1i is a constant and θ 11 =α1.

[0030] Optionally, the array of sub-pixels further includes a third sub-pixel, adjacent to the first sub-pixel. The third sub-pixel includes a light-emitting unit in the light-emitting layer and a transparent color-resisting unit in the wavelength conversion layer. The light-emitting unit and the transparent color-resisting unit are stacked and separated by the transparent spacer layer.

[0031] The light-emitting units of the first sub-pixel and the third sub-pixel are separated by the first pixel defining layer in the light-emitting layer, and the top surface spacing is d5.

[0032] The transparent color resist unit does not perform wavelength conversion on the light emitted by the light-emitting unit and has a brightness change rate of rc. The wavelength conversion unit of the first sub-pixel and the transparent color resist unit of the third sub-pixel are separated by the second pixel limiting layer in the wavelength conversion layer.

[0033] In the direction from the third sub-pixel to the first sub-pixel, the displacement of the orthographic projection on the substrate relative to the top surface of the light-emitting unit of the first sub-pixel and the boundary of the first pixel defining layer between the light-emitting units of the first and third sub-pixels, and the displacement of the bottom surface of the first wavelength conversion unit and the boundary of the second pixel defining layer between the wavelength conversion unit of the first sub-pixel and the transparent color resist unit of the third sub-pixel, is d43.

[0034] in,

[0035] Of the light incident from the top surface of the light-emitting unit onto the transparent spacer layer and reaching the top surface of the transparent spacer layer, the intensity of light with an exit angle greater than α3 accounts for less than x3%, where x3% = p3 × (rc / ra), and p3 ≤ 5%.

[0036] Wherein, when the emission angle of light originating from the bottom surface of the transparent spacer layer is α3, the length of the projection of the light path through the transparent spacer layer onto the substrate is less than or equal to d5+d43.

[0037] Optionally, the light-emitting unit emits blue light, the third sub-pixel is a blue sub-pixel, the first sub-pixel is a red sub-pixel, and the second sub-pixel is a green sub-pixel.

[0038] Alternatively, ra is in [110%, 180%], rb is in [25%, 70%], and rc is in [60%, 85%].

[0039] Optionally, the wavelength conversion unit comprises a quantum dot.

[0040] Optionally, the transparent spacer layer comprises a first inorganic layer, an organic layer, and a second inorganic layer stacked from bottom to top.

[0041] Optionally, the first inorganic layer is a SiNx layer, the second inorganic layer is a SiONx layer or an Al2O3 layer, and the organic layer is an epoxy resin layer or a polyacrylic resin layer.

[0042] Optionally, the thickness of the organic layer is in the range of 4 to 8 μm.

[0043] Optionally, the thickness of the organic layer is in the range of 0.3 to 0.6 μm.

[0044] Optionally, the top surface width of the second pixel defining layer is smaller than its bottom surface width.

[0045] Optionally, the second pixel defining layer includes a main body portion and a cover layer on the sidewall of the main body.

[0046] Optionally, the coating is an ink penetration protection layer.

[0047] Optionally, the coating may include a reflective material or a light-absorbing material.

[0048] Optionally, the coating material is metal.

[0049] Optionally, the overlay has a laterally extending portion at the bottom that covers the surface of the transparent spacer layer and extends away from the main body.

[0050] Optionally, the main body has an undercut, and the laterally extended portion of the covering layer covers the undercut.

[0051] Optionally, the depth of the undercut is in the range of 4 to 9 micrometers.

[0052] Optionally, a color filter layer on the wavelength conversion layer is also included.

[0053] In another aspect, this disclosure provides a method for preparing the above-described display panel, wherein the second pixel defining layer is prepared by the following steps:

[0054] Obtain the main body with an undercut;

[0055] A coating layer is sputtered and deposited on the surfaces of the transparent spacer layer and the main body.

[0056] The coating on the top surface of the main body and the portion of the coating on the transparent spacer layer not covered by the top surface of the main body are removed by dry etching, while the coating on the sidewalls of the main body and the undercut are retained.

[0057] Alternatively, the undercut body portion can be obtained by low-temperature curing of a black material.

[0058] Optionally, the transparent spacer layer includes an organic layer, which is prepared by molecular layer deposition.

[0059] In another aspect, this disclosure provides a display device comprising the above-described display panel or a display panel prepared according to the above-described method. Attached Figure Description

[0060] Figure 1(a) and (b) show schematic diagrams of the optical paths of light incident at large angles in the color filter layer and the wavelength conversion layer, respectively.

[0061] Figure 2 A partial schematic diagram of the relevant film layers of the display panel is shown.

[0062] Figure 3 It shows Figure 2 The cross-sectional view of the sub-pixel within the dashed box at position A-A' in the XZ plane.

[0063] Figure 4 It shows Figure 2 A cross-sectional view of a pixel containing three side-by-side sub-pixels at position A-A' in the XZ plane.

[0064] Figure 5 (a)-(f) schematically illustrate the division of the layer structure.

[0065] Figure 6 (a)-(b) schematically illustrate the principles of this disclosure and the structure between two adjacent sub-pixels in one embodiment.

[0066] Figure 7 An example of an emission angle-light intensity curve is shown.

[0067] Figure 8 It shows Figure 6 The schematic optical path in the transparent spacer layer is shown.

[0068] Figure 9 The schematic illustration shows the structure between two adjacent sub-pixels in one embodiment of this disclosure.

[0069] Figure 10 It shows in Figure 2 The cross section in the YZ plane.

[0070] Figure 11 A schematic shape of the second pixel-defined layer is shown.

[0071] Figure 12 A schematic diagram of a second pixel-defining layer with an ink penetration protection layer on the sidewall is shown.

[0072] Figure 13 A schematic diagram of a structure with an extended ink penetration protective layer at the bottom is shown.

[0073] Figure 14 SEM images of a metal ink penetration protective layer with undercut and sidewalls are shown.

[0074] Figure 15A schematic diagram of one embodiment of the QD-OLED display panel of this disclosure, which also includes a color filter layer, is shown.

[0075] Figure 16 An embodiment of the light-emitting layer-related structure is shown. Detailed Implementation

[0076] The inventors discovered that color crosstalk between adjacent subpixels is a prominent problem for display panels containing wavelength conversion elements, particularly QD conversion layers.

[0077] In related technologies, the backlight in an OLED-type color filter display panel is replaced with light, such as blue light, that can excite wavelength conversion units. Then, the color filter layer is replaced with a wavelength conversion layer of similar size, thereby achieving color emission through wavelength conversion instead of filtering. Furthermore, another color filter layer can be added to further purify the wavelength-converted color light. It should be noted that although wavelength conversion elements are sometimes referred to as color filters (e.g., QD color filters) in related technologies, in this disclosure, the color filter layer specifically refers to a layer that selectively transmits light of a specific wavelength.

[0078] However, wavelength-conversion display panels, such as QD-OLED, exhibit significantly greater color crosstalk issues than OLED-color filter display panels. Color crosstalk occurs when the light emitted by one sub-pixel causes adjacent sub-pixels to appear colored. As a result, adjacent sub-pixels emit light even when they shouldn't, which is particularly detrimental when adjacent sub-pixels are of different colors. Severe color crosstalk significantly impacts display quality. When the geometric parameters of a white OLED-color filter display panel are directly applied to, for example, a blue OLED-wavelength-conversion display panel, significant color crosstalk affecting display quality will occur. While the occurrence of color crosstalk has been noted in related technologies, its specific causes and solutions are still under investigation.

[0079] Without relying on any theory, the inventors of this disclosure unexpectedly discovered that in wavelength-conversion display panels, the wavelength conversion mechanism in the wavelength conversion layer enhances color crosstalk. In conventional color filter layers, even with backlight from adjacent sub-pixels incident from the bottom surface, due to the large incident angle, it travels almost in a straight line after entering the color filter layer. Part of it strikes the sidewalls of the color filter layer and cannot exit the light-emitting surface, while another part may undergo total internal reflection at the light-emitting surface and fail to escape. Even if a small portion manages to escape, the large exit angle has virtually no impact on the display effect viewed from the front of the display panel. Moreover, this is essentially the case even when scattering particles are present in the color filter to widen the viewing angle, because the scattering particles are unlikely to scatter most of the incident light at a large deflection angle to the front of the color filter layer. In contrast, in the wavelength conversion layer, the incident light undergoes photoluminescence at the light conversion point (e.g., quantum dot particles), i.e., re-emission. The emitted light angle is independent of the incident light angle, so a large amount of light will be emitted from the front, resulting in a much more severe color bleeding phenomenon than that of a color filter display panel with the same geometric design.

[0080] Figure 1 (a) and (b) show schematic diagrams of the optical paths of light incident at large angles in the color filter layer and the wavelength conversion layer, respectively. Figure 1 (a) shows the color filter layer. Two adjacent sub-pixels are schematically shown in the figure. Figure 1 In (a), each of the two adjacent sub-pixels includes a light-emitting unit 31 serving as a backlight layer and a color filter 51 for filtering. When there are no scattering particles in the color filter layer, the light emitted by the light-emitting unit of the backlight layer of the left sub-pixel enters the bottom surface of the color filter layer of its adjacent right sub-pixel, resulting in a large exit angle, and then travels in a straight line. Route P1 indicates that it reaches the sidewall of the color filter layer and cannot exit. Route P2 indicates that although it reaches the top surface of the color filter layer (i.e., its light-emitting surface), it cannot exit due to total internal reflection. Route P3 indicates that even if it exits, the exit angle is large and will not affect the frontal view. Furthermore, even if there are scattering particles in the color filter layer, their overall impact on the light path is relatively limited, and will not cause most of the incident light to exit from the light-emitting surface with a small exit angle. Therefore, in the design of color filter layer OLEDs, the crosstalk problem can be basically solved by appropriately designing the size so that the incident angle of the backlight from the adjacent sub-pixels in the color filter layer is large. In contrast, Figure 1 (b) illustrates the case of wavelength conversion layer 11 of the same size. This is due to the presence of a large number of wavelength conversion particles (e.g., quantum dot particles) in the wavelength conversion layer. Figure 1In (a), the same incident light beams P1, P2, and P3 will inevitably encounter wavelength-converting particles during their journey through the wavelength conversion unit. At the wavelength-converting particles, the incident light undergoes wavelength conversion, becoming a new emission. Its emission direction is no longer limited by the incident angle and can exit from the front of the wavelength conversion unit, thus causing color crosstalk. At least partly due to the above reasons, the design of color filter-type OLED display panels cannot avoid the color crosstalk problem inherent in wavelength-converting display panels.

[0081] One possible solution to this problem is to increase the spacing between sub-pixels to prevent light leakage. However, the relevant technologies have not identified an optimal level for increasing the sub-pixel spacing. The inventors discovered that since cross-color mixing originates from photoluminescence caused by incident light, simply increasing the distance between adjacent sub-pixels cannot completely prevent light leakage and may unnecessarily reduce resolution. While it is possible to add opaque vertical light-blocking layers between adjacent pixels to prevent light leakage, such methods would significantly increase manufacturing complexity and material costs, hindering production.

[0082] To at least partially address the above problems, this disclosure provides the following:

[0083] The light-emitting layer on the substrate

[0084] The transparent spacer layer on the light-emitting layer, and

[0085] Wavelength conversion layer on the transparent spacer layer,

[0086] The display panel includes an array of sub-pixels, each sub-pixel comprising adjacent first and second sub-pixels. Each of the first and second sub-pixels includes a light-emitting unit in the light-emitting layer and a wavelength conversion unit in the wavelength conversion layer. The light-emitting unit and the wavelength conversion unit are stacked and separated by the transparent spacer layer.

[0087] The light-emitting units of the first sub-pixel and the second sub-pixel are separated by the first pixel defining layer in the light-emitting layer, and the top surface spacing is d2.

[0088] The wavelength conversion unit of the first sub-pixel is a first wavelength conversion unit and its brightness change rate for the light emitted by the light-emitting unit is ra; the wavelength conversion unit of the second sub-pixel is a second wavelength conversion unit and its brightness change rate for the light emitted by the light-emitting unit is rb; the wavelength conversion units of the first sub-pixel and the second sub-pixel are separated by a second pixel defining layer in the wavelength conversion layer.

[0089] In the direction from the first sub-pixel to the second sub-pixel, the displacement of the orthographic projection on the substrate relative to the top surface of the light-emitting unit of the second sub-pixel and the boundary of the first pixel defining layer between the light-emitting units of the first and second sub-pixels, and the displacement of the bottom surface of the second wavelength conversion unit and the boundary of the second pixel defining layer between the wavelength conversion units of the first and second sub-pixels, relative to the boundary of the first pixel defining layer between the light-emitting units of the second and second sub-pixels, is d42.

[0090] in,

[0091] Of the light incident from the top surface of the light-emitting unit onto the transparent spacer layer and reaching the top surface of the transparent spacer layer, the intensity percentage of light with an exit angle greater than α1 is less than x1%, where x1% = p1 × (ra / rb), and p1 ≤ 5%.

[0092] Wherein, when the emission angle of light originating from the bottom surface of the transparent spacer layer is α1, the length of the projection of the light path through the transparent spacer layer onto the substrate is less than or equal to d2+d42.

[0093] The display panel disclosed herein comprises at least three layers on a substrate in the thickness direction: a light-emitting layer, a transparent spacer layer, and a wavelength conversion layer. The light-emitting layer is responsible for emitting light. The transparent spacer layer separates the light-emitting layer and the wavelength conversion layer, and can encapsulate or support both. The transparent spacer layer is a material layer that is transparent at least in the visible light range. Thus, light emitted from the light-emitting unit can pass through the transparent spacer layer and reach the wavelength conversion unit. The wavelength conversion layer converts the wavelength of the light emitted from the light-emitting layer and passing through the transparent spacer layer into the desired wavelength to achieve color display. The substrate supports the aforementioned three-layer structure. Furthermore, similar to conventional display panels, the display panel of this disclosure also includes an array of sub-pixels for display purposes. Figure 2 A partial schematic diagram of the relevant film layers of the display panel is shown.

[0094] like Figure 2 As shown, the display panel extends in the XY plane, with its thickness along the Z direction. The Z direction is the direction from the back side to the front side of the display panel. Along the Z direction, there are, in sequence, a substrate 4, a light-emitting layer 3, a transparent spacer layer 2, and a wavelength conversion layer 1. In this disclosure, unless otherwise specified, the light-emitting side of the display panel is referred to as the "top side" or "front side," and its opposite side as the "bottom side" or "back side," for ease of describing relative directions. Correspondingly, the direction perpendicular to the direction from the bottom side to the top side is called the "lateral direction." It should be understood that these directions are relative rather than absolute.

[0095] Viewed from the front of the display panel, it comprises subpixels arranged in an array. Subpixels are typically arranged in a rectangular array, but other suitable array arrangements are also permissible, provided they do not conflict with the principles of this disclosure. Figure 2 The diagram illustrates a 6×3 rectangular array of subpixels. If the X-direction is the row direction and the Y-direction is the column direction, the subpixels in the diagram are arranged in a 3x6 array. They form a 3x2 array of 6 pixels, with each pixel containing 3 subpixels arranged in the row direction. This disclosure does not require different colors of subpixels to be arranged in a specific pattern; for example, the arrangement could be such that 3 subpixels in the same pixel are different colors, while subpixels in the same column are the same color, or other patterns are also possible. The subpixels are rectangular, with the longer side in the Y-direction and the shorter side in the X-direction. All subpixels in the diagram are drawn to the same size. It should be understood that the color distribution, shape, and size of the subpixels can be appropriately chosen, as long as they do not conflict with the principles of this disclosure. Figure 2 The dashed box in the image indicates the approximate range of one of the sub-pixels.

[0096] The array of sub-pixels comprises adjacent first and second sub-pixels. Each of the first and second sub-pixels includes a light-emitting unit in the light-emitting layer and a wavelength conversion unit in the wavelength conversion layer. The light-emitting unit and the wavelength conversion unit are stacked and separated by the transparent spacer layer. "Stacked" means they overlap in the thickness direction (Z-direction) of the display panel. In other words, each of the first and second sub-pixels includes a light-emitting unit in the light-emitting layer and a wavelength conversion unit in the wavelength conversion layer. The wavelength conversion unit receives light emitted upwards from the top surface of the light-emitting unit below it at its bottom surface, converts the light wavelength, and emits it from the top of the wavelength conversion unit to complete the display.

[0097] Figure 3 It shows Figure 2 The diagram shows a schematic cross-sectional view of the sub-pixel within the dashed box at position A-A' in the XZ plane. This sub-pixel comprises a light-emitting unit 31 stacked in the light-emitting layer 3 and a wavelength-converting unit 11 stacked in the wavelength-converting layer 1, separated by a transparent spacer layer 2. The interface between the light-emitting unit 31 and the transparent spacer layer 2, i.e., its top surface, emits light into the transparent spacer layer. The interface between the wavelength-converting unit 11 and the transparent spacer layer 2, i.e., its bottom surface, receives light from the transparent spacer layer, and the light, after wavelength conversion, exits from its top surface. The wavelength-converting unit 11 and the light-emitting unit 31 are vertically opposite each other; in other words, the orthographic projections of the bottom surface of the wavelength-converting unit and the top surface of the light-emitting unit onto the substrate overlap. Therefore, most of the light emitted from the top surface of the light-emitting unit 31 passes through the transparent spacer layer and reaches the lower surface of the wavelength-converting unit 11, entering the wavelength-converting unit 11. The wavelength-converting particles in the wavelength-converting unit convert the wavelength of the incident light and exit from its top surface.

[0098] As described above, the light-emitting layer is the layer that emits light. The light emitted from it passes through the wavelength conversion layer above it and can be converted into other colors, or it can optionally not be converted into colors, thereby achieving color display.

[0099] The light emission of the display panel disclosed herein is achieved by light-emitting units in the light-emitting layer. Typically, the light-emitting units are arranged in an array. The light-emitting units can typically use OLED light emission, but other light emission modes are also possible, such as QLED, Mini-LED, or Micro-LED using inorganic quantum dot light-emitting materials. In the light-emitting layer, multiple such light-emitting units are arranged in an array parallel to the display surface of the display panel, thereby forming a light-emitting dot matrix. Each sub-pixel of the display panel disclosed herein has an independent light-emitting unit, which can be used in conjunction with, for example, an array substrate to achieve individual lighting and extinguishing of the backlight of each sub-pixel. In one embodiment of the present disclosure, the light-emitting units of sub-pixels of different colors are identical.

[0100] The light-emitting layer includes a first pixel defining layer that defines the array of light-emitting units. It should be understood that the "first pixel defining layer" referred to in this disclosure actually defines the range of individual sub-pixels, such as the range of red, green, and blue sub-pixels, rather than the total range of a single color RGB pixel.

[0101] The patterned first pixel limiting layer is set in the light-emitting layer, forming an array of spaces for setting the light-emitting units. Figure 3 In the middle, the light-emitting unit 31 is defined on both sides by the first pixel limiting layer 32.

[0102] although Figure 3 The first pixel defining layer and the light-emitting unit illustrated are both rectangular with vertical sidewalls, but they can also have inclined sidewalls. For example, the first pixel defining layer can be a regular trapezoid, and a corresponding inverted trapezoidal light-emitting unit is formed. The regular trapezoidal first pixel defining layer can provide a larger light-emitting surface, and a reflective layer can also be provided on the sidewalls of the first pixel defining layer, thereby increasing the light emission of the light-emitting unit. This disclosure focuses on the geometric features at the top of the first pixel defining layer and the top surface of the light-emitting unit; therefore, the shape of the first pixel defining layer and the light-emitting unit is not particularly limited.

[0103] The display panel disclosed herein includes a wavelength conversion element. The wavelength conversion element is used to convert the wavelength of light emitted by the light-emitting unit into other colors. It should be noted that in this disclosure, wavelength conversion differs from wavelength selective transmission. Wavelength conversion refers to converting the wavelength of incident light to another wavelength without requiring additional energy, while wavelength selective transmission refers to allowing only a portion of the incident light wavelengths to pass through while blocking other wavelengths. Wavelength conversion can be either down-conversion or up-conversion. Down-conversion, the opposite of up-conversion, refers to converting shorter wavelength light into longer wavelength light. By using different wavelength conversion units to change the color of light, color display can be achieved using only a single color of light-emitting unit.

[0104] The wavelength conversion layer includes wavelength conversion units that convert the wavelength emitted by the light-emitting units in the sub-pixels into the desired color. For example, a red wavelength conversion unit can convert blue backlight into red light, and a green wavelength conversion unit can convert blue backlight into green light. Examples of wavelength conversion units can be a quantum dot (QD) material section, an inorganic phosphor material section, or an organic fluorescent material section, comprising a transparent matrix material and quantum dots, inorganic phosphors, or organic fluorescent materials dispersed in the matrix material. Wavelength conversion units can also be made of other wavelength conversion materials. The matrix material can be a transparent organic material such as a resin, for example, cured photoresist resin, or cured ink. Any suitable downconversion material can be used, and this disclosure does not particularly limit its application. QD downconversion materials are particularly preferred because their downconversion performance can be controlled by particle size.

[0105] In one embodiment, the wavelength conversion unit may include a base resin and quantum dots mixed with (or dispersed in) the base resin. The base resin may be a medium in which the quantum dots are dispersed. The base resin may be formed from at least one of a variety of resin composite materials commonly referred to as binders. However, the inventive concept is not limited thereto. For example, a medium capable of dispersing quantum dots may be used as the base resin, regardless of its name, additional functions, and / or constituent materials. In some exemplary embodiments, the base resin may be a polymeric resin. For example, the base resin may be an acrylic resin, a urethane resin, a silicone resin, or an epoxy resin. The base resin may be a transparent resin.

[0106] Quantum dots can be particles configured to convert the wavelength of incident light. Each quantum dot can be a material with a crystal structure several nanometers in size and can consist of hundreds to thousands of atoms. Quantum dots can exhibit a quantum confinement effect, where the band gap is increased due to their small size. When light of a wavelength corresponding to an energy greater than the band gap is incident on a quantum dot, the quantum dot can be excited by absorbing the light and can then transition to its ground state while emitting light of a specific wavelength. The energy of the emitted light can correspond to the band gap. The luminescence properties of quantum dots caused by the quantum confinement effect can be tuned by adjusting the size and / or composition of the quantum dots.

[0107] Quantum dots can be formed from group II-VI compounds, group III-V compounds, group IV-VI compounds, group IV elements, group IV compounds, or any combination thereof.

[0108] Group II-VI compounds may be selected from the following groups: binary compounds selected from the group consisting of CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS and any mixture thereof; and compounds selected from the group consisting of AgInS, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnT. Ternary compounds consisting of the group consisting of e, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS and any mixture thereof; and quaternary compounds selected from the group consisting of HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe and any mixture thereof.

[0109] III-V group compounds may be selected from the following groups: binary compounds selected from the group consisting of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb and any mixture thereof; ternary compounds selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb and any mixture thereof; and quaternary compounds selected from the group consisting of GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb and any mixture thereof. Group IV-VI compounds may be selected from the following groups: binary compounds selected from the group consisting of SnS, SnSe, SnTe, PbS, PbSe, PbTe, and any mixture thereof; ternary compounds selected from the group consisting of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, and any mixture thereof; and quaternary compounds selected from the group consisting of SnPbSSe, SnPbSeTe, SnPbSTe, and any mixture thereof. Group IV elements may be selected from the group consisting of Si, Ge, and mixtures thereof. Group IV compounds may be binary compounds selected from the group consisting of SiC, SiGe, and mixtures thereof.

[0110] In these cases, binary, ternary, or quaternary compounds can exist in the quantum dot at substantially uniform concentrations. Alternatively, the concentration of binary, ternary, or quaternary compounds in one part of the quantum dot can differ from the concentration of binary, ternary, or quaternary compounds in another part of the quantum dot.

[0111] Each quantum dot can have a core-shell structure comprising a core and a shell surrounding the core. Alternatively, a quantum dot can have a core / shell structure in which one quantum dot surrounds another quantum dot. The interface between the core and the shell can have a concentration gradient, wherein the concentration of the element present in the shell gradually decreases toward the center.

[0112] Quantum dots can be nanoscale particles. Each quantum dot can have a full width at half maximum (FWHM) of an emission wavelength spectrum of about 45 nm or smaller, specifically about 40 nm or smaller, and more specifically about 30 nm or smaller, and color purity and / or color reproducibility can be improved within this range. Furthermore, light emitted through quantum dots can be emitted in all directions, and therefore, wide viewing angles can be improved or achieved.

[0113] Furthermore, the shape of each quantum dot can be a general shape known in the art, but the shape of each quantum dot is not limited to a specific shape. For example, each quantum dot can have a spherical shape, a pyramidal shape, a multi-armed shape, a cubic nanoparticle shape, a nanotube shape, a nanowire shape, a nanofiber shape, or a nanoplate particle shape. The color of the light emitted from the quantum dots can be controlled according to the particle size of the quantum dots, and therefore, quantum dots can emit one of a variety of emitted colors of light, such as red, green, or blue, especially red or green.

[0114] In this application, unless otherwise specified, QD is used as an example of wavelength conversion material for illustration.

[0115] The wavelength conversion unit in the wavelength conversion layer includes a first wavelength conversion unit, which converts incident light into light of a first color. For example, the first color can be red, meaning there is a red wavelength conversion unit within the wavelength conversion layer. It should be understood that terms like "first color," "second color," etc., are used only to distinguish colors and not to assign any order to them. To achieve color display, the wavelength conversion unit in the wavelength conversion layer may also include a second wavelength conversion unit or more other wavelength conversion units. For example, red can be selected as the first color and green as the second color. Or, for another example, red can be used as the first color, green as the second color, and blue as the third color.

[0116] Optionally, in addition to the wavelength conversion unit, the wavelength conversion layer may also include a transparent color resist unit. The transparent color resist unit is transparent to incident light and does not undergo wavelength conversion. Thus, for example, blue OLED light emitted from a blue subpixel can pass through the wavelength conversion layer without undergoing wavelength conversion, and can be directly used for blue display. Preferably, the transparent color resist unit can be a light diffusion unit, for example, containing scattering particles, so that the incident light is scattered without a substantial change in wavelength, which is beneficial for uniform display. The light diffusion unit can be made of a light-diffusing resin with light-diffusing capabilities, thereby making the blue light more uniform after passing through it.

[0117] In one embodiment, the display panel of this disclosure can be a down-conversion OLED display panel. A down-conversion OLED display panel uses a short-wavelength OLED of a single color as the light-emitting unit, typically a blue OLED. In sub-pixels of different colors, different down-conversion materials (such as QD) are used to down-convert the aforementioned short-wavelength light into light with relatively longer wavelengths, thereby achieving color display based on the same color light-emitting unit. As an example, for all color sub-pixels, a short-wavelength blue OLED is used for light emission. In the red sub-pixel, the down-conversion material converts the blue light emitted by the blue OLED into red light. In the green sub-pixel, the down-conversion material converts the blue light emitted by the blue OLED into green light. Furthermore, since blue itself is one of the sub-pixel colors for RGB display, in the blue sub-pixel, down-conversion of the blue light is not required, and it can be directly used for blue sub-pixel display. Of course, a blue conversion material can also be used to adjust the color of the blue pixel. Thus, red, green, and blue (RGB) color display is achieved. In the following discussion of this disclosure, the use of blue backlight as a short-wavelength backlight and down-conversion to green and red light as examples are sometimes used in the explanation. However, it should be understood that, depending on the need, other colors of light or other colors of converted light can also be selected.

[0118] The patterned second pixel limiting layer is set in the wavelength conversion layer, forming an array of spaces for setting wavelength conversion units. Figure 3 In the middle, the bottom surfaces of the wavelength conversion unit 11 are defined by the bottom of the second pixel defining layer 12 on both sides. Figure 3 The second pixel defining layer and wavelength conversion unit shown in the diagram are both rectangular and have vertical sidewalls. However, they can also have sloping sidewalls. The second pixel defining layer also serves to enclose the space where the transparent color resist unit is disposed. The specific shape of the second pixel defining layer will be further described below.

[0119] Figure 4 It shows Figure 2 A cross-sectional view of a pixel containing three side-by-side sub-pixels at position A-A' in the XZ plane. A first pixel defining layer 32 defines three light-emitting units 31a, 31b, and 31c, while a second pixel defining layer 12 defines three units 11a, 11b, and 11c. As an example, 11a and 11b are wavelength conversion units, and 11c is a transparent color resist unit.

[0120] The figure shows adjacent sub-pixels. As mentioned earlier, the sub-pixels of this disclosure can be either sub-pixels containing wavelength conversion units or sub-pixels containing transparent color resist units. However, in order to achieve the display of at least three colors, at least two adjacent sub-pixels in this disclosure must both contain wavelength conversion units and have different colors. The third color can be obtained by converting the light emitted by the light-emitting unit through the wavelength of another color, or by passing the light emitted by the light-emitting unit through the transparent color resist unit. Therefore, in this disclosure, any two adjacent sub-pixels that both have wavelength conversion units can be selected as the first and second sub-pixels, and their order can also be interchanged.

[0121] In this disclosure, the emissive layer includes a first pixel defining layer and emissive units, the wavelength conversion layer includes a second pixel defining layer and wavelength conversion units, and a transparent spacer layer is located between the emissive layer and the wavelength conversion layer. The bottom surface of the transparent spacer layer is the top surface of the emissive units in the emissive layer, and the top surface of the transparent spacer layer is the bottom surface of the wavelength conversion units (or transparent color resist units) in the wavelength conversion units. Figure 4 As shown, the top surface of the first pixel limiting layer 32 and the top surface of the light-emitting unit 31 in the light-emitting layer 3 are in the same plane, and this plane is the bottom surface of the transparent spacer layer 2. The bottom surface of the second pixel limiting layer 12 and the bottom surface of the wavelength conversion unit / transparent color resist unit 11 in the wavelength conversion layer 1 are in the same plane, and this plane is the top surface of the transparent spacer layer 2.

[0122] It should be noted that the interface relationships between the aforementioned layers are derived from their geometric divisions. In other words, considering the deviation between the actual structure and the ideal or standard geometry, the interfaces of the aforementioned layers are not necessarily the actual interfaces of the materials.

[0123] For example, the top and bottom surfaces of the transparent spacer layer are not necessarily the actual interface between different materials; they can also be dividing surfaces defined within the same material. As another example, a portion of the top of the first pixel-defining layer may actually be within the geometric range of the transparent spacer layer.

[0124] In this disclosure, for the actual film structure, the reference for the bottom surface of the transparent spacer layer, i.e. the top surface of the light-emitting layer, is determined based on the shape of the top surface of the first pixel defining layer, and the reference for the top surface of the transparent spacer layer, i.e. the bottom surface of the wavelength conversion layer, is determined based on the shape of the bottom surface of the second pixel defining layer.

[0125] Taking the first pixel defining layer as an example, ideally, the top surface of the first pixel defining layer is a plane. In this case, its top surface can be used as the reference plane for the top surface of the light-emitting layer. Directly above it is the transparent spacer layer. On both sides, the portion below the reference plane is assigned to the light-emitting unit, and the portion above the reference plane is assigned to the transparent spacer layer.

[0126] However, such an ideal partitioning may be difficult to achieve in actual devices. For example, the top of the first pixel defining layer may be non-planar and slightly convex in the center. In this case, the first pixel defining layer does not have a flat top surface. However, a planar interface still needs to be defined between the first pixel defining layer and the transparent spacer layer.

[0127] Since the pixel-defining layer blocks light leakage between adjacent sub-pixels, when considering cross-color leakage, a point is considered on the boundary of the first pixel-defining layer that can receive sufficient illumination from the luminescent material layer of the luminescent unit and also provide corresponding illumination to the adjacent wavelength conversion unit. In this disclosure, the inflection point where the slope change rate is the largest on the profile of the first pixel-defining layer is selected as the aforementioned point. After selecting such points on both sides of the first pixel-defining layer, their average height is used as the reference for dividing the transparent spacer layer and the luminescent layer. Since this reference depends on the profile of the first pixel-defining layer, it is independent of the actual boundary of the material. In the space above this reference, some material of the first pixel-defining layer (e.g., the slightly protruding portion mentioned above) may actually exist. In the space below the reference on both sides of the first pixel-defining layer, some material identical to the transparent spacer layer material may also actually exist. After dividing according to this reference, the actual film structure is fitted as a film with a standard flat interface, and further calculations and designs are performed. Specifically, the width occupied by the first pixel-defining layer on the reference line is taken as the width d2 between the top surfaces of adjacent luminescent units.

[0128] The following are some specific examples of the division to illustrate this.

[0129] A typical light-emitting unit includes an anode, a light-emitting material layer, and a cathode, and the cathode is usually a common cathode that covers the top of the light-emitting material layer and the first pixel defining layer. For example, Figure 5 (a) shows a typical structure. Here, 311 is the anode, 313 is the light-emitting material layer, and 315 is the common cathode. In this case, the top surface of the first pixel defining layer is used as the reference for dividing the light-emitting layer and the transparent spacer layer. This is because the light emission at the endpoints of the top surface best represents the principle of this disclosure. As shown, the light-emitting layer 3 and the transparent spacer layer 2 are divided based on the line connecting the upper left corner A1 and the upper right corner A2 of the trapezoid and its extension. At this time, the common cathode above the first pixel defining layer also falls within the scope of the transparent spacer layer.

[0130] For example, Figure 5 (b) shows another typical case where the common electrode 315 and its underlying surface are contoured, and the upper surface is uneven. However, this does not affect the division between the transparent spacer layer and the light-emitting layer. The two endpoints of the top surface of the first pixel defining layer are still used as the division reference.

[0131] As mentioned above, such as Figure 5 Figures (a) and (b) show a more ideal standard shape, where the first pixel defining layer and the light-emitting unit share a common planar top surface, which serves as the interface between the light-emitting layer and the transparent spacer layer. In this case, the straight boundaries of each part are clear. However, in actual devices, the interfaces may not be ideally planar. In this case, representative points are selected to determine the geometric parameters.

[0132] The interface in the actual structure of the display panel may have some distortions. However, they can be reduced to a standard shape.

[0133] For example, Figure 5 (c) shows a comparison Figure 5 (a) A more complex structure around the pixel-defining layer. The top surface of the first pixel-defining layer 32 is slightly convex, no longer an ideal plane. In this case, as shown in the figure, the position with the largest rate of change of the tangent slope on the first pixel electrode layer is selected as the top surface position of the light-emitting unit and the bottom surface position of the transparent spacer layer. The position with the largest rate of change of the tangent slope is the inflection point where the basically vertical sidewall of the first pixel electrode layer transitions to the basically horizontal top surface. At this position, sufficient light from the light-emitting material layer 313 can be obtained, and there is enough light to be emitted laterally without being blocked by the first pixel-defining layer 32. In fact, in the case of a standard trapezoidal first pixel-defining layer, the endpoint of the top surface is the position with the largest rate of change of the tangent slope.

[0134] For example, Figure 5 (d) illustrates a more complex structure. The first pixel defining layer 32 itself forms a "mushroom shape" that is wider at the top and narrower at the bottom. Here, the inflection point with the largest rate of change of the tangent slope above the widest point (dashed line position) of the first pixel defining layer is chosen as the position of the top surface of the light-emitting unit and the bottom surface of the transparent spacer layer. This is because, below the widest point, the light emitted from points on the sidewalls of the first pixel defining layer cannot reach adjacent sub-pixels, and therefore need not be considered. It should be understood that this disclosure considers light emission near the top surface of the first pixel defining layer and light incidence near the bottom surface of the second pixel defining layer; therefore, the geometry of other parts of the first or second pixel defining layer is not the focus of this disclosure. For example, the cross-section of the first pixel defining layer can be a regular trapezoid with a narrow top and a wide bottom, a rectangle with almost the same width at the top and bottom, or an inverted trapezoid with a wide top and a narrow bottom. This has little impact on determining the distance d2 between the light-emitting units.

[0135] Accordingly, in Figure 5 (d) determines the layering interface between the light-emitting layer 3 and the transparent spacer layer 2 based on the inflection point position.

[0136] It should be understood that Figure 5The tangents in (c) and (d) refer to the overall profile, ignoring the minute irregularities on the wall.

[0137] The above are merely some examples of standardized regional divisions of real structures. Real structures can be correctly divided based on the principles of this disclosure, and all real structures that conform to the limitations of this disclosure are within its protection scope.

[0138] As described above, when the thickness of the cathode at the top of the first pixel defining layer is different from its thickness at the top of the light-emitting material layer, the portion of the cathode above the top surface of the first pixel defining layer can be used as part of the transparent spacer layer, while the portion of the cathode between the first pixel defining layers and below the top surface of the first pixel defining layer can be used as part of the light-emitting unit.

[0139] For example, Figure 5 (e) illustrates the layer structure partitioning in one embodiment when the lower surface of the common cathode is not planar. A first pixel defining layer 32 defines the height of the light-emitting layer 3, and a portion of the common cathode 315 covering it is below the top surface of the first pixel defining layer 32. In this case, the portion of the common cathode 315 above the first pixel defining layer can be considered part of the transparent spacer layer 2, while the portion between the first pixel defining layers 32 can be considered part of the light-emitting unit 31. The boundary between the transparent spacer layer 2 and the light-emitting layer 3 is indicated by the dashed line below.

[0140] Apart from the common cathode, other film layers having portions above the top height of the first pixel-defined layer can also be divided in this way.

[0141] In the direction perpendicular to the paper, the boundary between the first pixel defining layer and the light-emitting unit may not be a straight line. In this case, the boundary is represented by a straight average line.

[0142] In summary, in principle, the position of the top surface of the first pixel-defining layer is used as the reference for determining the light-emitting layer and the transparent spacer layer. When there is a slight height difference between the boundary points of the top surfaces of the first pixel-defining layer and the light-emitting units on both sides, the height of the standard plane top surface can be obtained by averaging the heights of these boundary points. When the top surface of the first pixel-defining layer is slightly raised relative to the top surfaces of the light-emitting units on both sides, the inflection point of the tangent slope at the top of the pixel-defining layer can be used as the boundary point of the top surface of the light-emitting unit.

[0143] Similarly, the wavelength conversion layer can be geometrically standardized.

[0144] For example, such as Figure 5As shown in (e), particularly when assembling the wavelength conversion layer 1 and the light-emitting unit 3 using a cell-to-cell method, the wavelength conversion layer 1 may have a cover layer or encapsulation layer 113 covering the wavelength conversion material 111. A transparent encapsulation layer 21 may be present between the cover layer 113 and the common cathode 315. Similarly, the interface between the wavelength conversion layer and the transparent spacer layer is defined with the bottom surface of the second pixel defining layer as a reference. A portion of the cover layer 113 is incorporated into the wavelength conversion unit 11, and another portion is incorporated into the transparent spacer layer 2. The boundary between the transparent spacer layer 2 and the wavelength conversion layer 1 is indicated by the dashed line above.

[0145] For example, Figure 5 (f) illustrates how, when the bottom surface of the second pixel defining layer is not planar, inflection points are similarly determined to delineate the interface between the wavelength conversion layer and the transparent spacer layer. Here, 12 is the second pixel defining layer. It has sub-pixels a and b on both sides, each with wavelength conversion units 111a and 111b, and both the second pixel defining layer 12 and the wavelength conversion units 111a and 111b are covered by the encapsulation layer 113. Inflection points B1 and B2 are determined based on the profile shape of the bottom surface of the second pixel defining layer 12, and their average height is used as a reference to delineate the boundary between the wavelength conversion layer 1 and the transparent spacer layer 2. A portion of the encapsulation layer 113 belongs to the transparent spacer layer.

[0146] This disclosure provides a special size design for the regions between subpixels to at least partially solve the color mixing problem.

[0147] Figure 6 The principles of this disclosure are illustrated schematically. Figure 6 (a) is a schematic diagram showing a portion of sub-pixel a on the left and sub-pixel b on the right, defined by the first pixel defining layer 32 and the second pixel defining layer 12. The left sub-pixel a includes stacked light-emitting units 31a and wavelength conversion units 11a, and the right sub-pixel b includes stacked light-emitting units 31b and wavelength conversion units 11b. Ideally, the top surface of the first pixel defining layer 32 and the top surfaces of the light-emitting units 31a and 31b are in the same plane, and the bottom surface of the second pixel defining layer 12 and the bottom surfaces of the wavelength conversion units 11a and 11b are also in the same plane. The top surface of the light-emitting units is, for example, the top surface of the transparent pixel electrode of an OLED, such as a transparent cathode. The spacer layer is made of a single material. At this point, the light emitted from point A1, the boundary between 31a and 32, can reach the adjacent sub-pixel 11b in region I (the region to the right of line segment A1 to B2), and can reach the sub-pixel 11a in region II (the region to the left of line segment A1 to B1). However, the light emitted in region III (the region to the left of line segment A1 to B2 and the region to the right of line segment A1 to B1) will be blocked by 12. The light reaching 11b will cause 11b to emit light, which may cause color bleeding.

[0148] The concept of this disclosure is that, although some light inevitably shines towards region I and reaches 11b, as long as the resulting luminance of subpixel b is sufficiently small compared to the luminance of the luminous subpixel a, the viewer will not be able to detect the luminance of subpixel b, and no substantial color bleeding will occur. In other words, the purpose of this disclosure is to control the relative luminance of subpixel b rather than simply blocking light leakage between adjacent subpixels.

[0149] For the user, or viewer, of a display panel, the relative brightness of subpixels is the primary factor determining whether they can perceive color differences. Luminance is defined as the luminous intensity per unit projected area, measured in nits (cd / m²). 2 Luminous intensity is the luminous flux per unit solid angle. Luminous flux refers to the radiant power perceptible to the human eye, measured in lumens (lm). The luminous flux at a specific wavelength is proportional to the product of the radiant power and the relative vision rate at that wavelength. The relative vision rate is also known as the spectral luminous efficiency function or the human visual function. Standard spectral luminous efficiency functions can be obtained, for example, by the International Commission on Illumination (CIE).

[0150] The luminance observed from the front of the wavelength conversion unit is related to the initial power of the light source providing backlight to the wavelength conversion unit, the wavelength change caused by wavelength conversion, and the conversion capability of the wavelength conversion unit itself for incident light. In this disclosure, the ability of the wavelength conversion unit (or transparent color resist unit) to change luminance is summarized as the parameter "luminance change rate". In the wavelength conversion unit, the luminance change rate is used to represent the luminance change that occurs when incident light is converted into outgoing light due to the action of the wavelength conversion unit. Specifically, the luminance change rate is the ratio of the luminance of the wavelength-converted light emitted from the wavelength conversion unit to the luminance of the light incident on the wavelength conversion unit. It should be noted that some incident light may pass directly through the wavelength conversion unit without encountering wavelength conversion particles and without undergoing wavelength conversion. However, because a color filter is also provided in the display device to filter out excess backlight, the remaining luminance of the incident light after passing through the wavelength conversion unit will not significantly affect the final display luminance and will not affect color crosstalk. Therefore, in this disclosure, when considering the luminance change rate, only the luminance of the wavelength-converted light is calculated. The rate of change in brightness is influenced by both the change in light wavelength and the wavelength conversion capability. Changes in light wavelength affect the relative visibility component of brightness, while the wavelength conversion capability affects the change in photon number. In quantum dot wavelength conversion units, the wavelength conversion capability is affected by its quantum efficiency. In transparent color resist units, the rate of change in brightness represents the ratio of the brightness of light emitted from the transparent color resist unit to the brightness of light incident on the transparent color resist unit. Because the wavelength remains unchanged, the change in brightness is primarily affected only by the change in photon number. The rate of change in brightness for a specific wavelength conversion unit or transparent color resist unit for a specific incident light wavelength can be measured experimentally or calculated based on material properties.

[0151] For example, the brightness change rate can be obtained by illuminating the bottom surface of the wavelength conversion unit structure with a collimated backlight of known brightness and measuring the brightness of the wavelength-converted light on the top surface of the wavelength conversion unit. The wavelength conversion unit being tested can be a pre-fabricated simulated sample, allowing for dimensional design based on the test results.

[0152] The smaller the ratio (or relative brightness) of the luminance of the wavelength conversion unit 11b of sub-pixel b caused by the light-emitting unit 31a to the luminance of 11a of sub-pixel a, the weaker the color crosstalk performance. In this disclosure, the ratio of the luminance of the wavelength conversion unit of an adjacent sub-pixel (e.g., pixel b) to the luminance of the wavelength conversion unit of the sub-pixel providing light (e.g., pixel a) is represented by the parameter p.

[0153] The inventors discovered through simulation that different critical p-values ​​exist for different color combinations, and below this critical p-value, it can be completely ensured that color bleeding is imperceptible to the human eye. In some embodiments, the critical p-value is specified to be less than 5%. More preferably, the critical p-value is specified to be less than 3.1%. Most preferably, the critical p-value is less than 2%. At less than 2%, for any color combination, it can be ensured that there is no observable color bleeding.

[0154] This disclosure ensures that the aforementioned p-value is below a desired critical value by designing the geometry between sub-pixels. Figure 6 In (a), the emission of 11b caused by the emission of A1 (wavelength conversion emission) is caused by the light emitted into region I, while the emission of 11a caused by A1 is caused by the light emitted into region II.

[0155] Note that wavelength-converted emission affects the brightness of the light because it changes the wavelength. When the wavelengths converted in 11a and 11b are different, the displayed brightness will be different even when illuminated by the same intensity of light.

[0156] In this disclosure, the parameter r is used to characterize the proportion by which the wavelength conversion material changes the brightness of the incident light. That is, when the brightness of the incident light is B, the brightness of the emitted light is B×r. The brightness change rate of the first sub-pixel a is called ra, and the brightness change rate of the second sub-pixel is called rb. ra and rb are parameters related to the material properties. It should be noted that, due to the change in wavelength, the brightness change rate can be a value greater than 100%.

[0157] Therefore, if the total brightness of the light incident on 11b is B I The resulting total brightness of the emitted light is B. I ×rb, the total luminance of the incident light 11a is D II The resulting total brightness of the emitted light is D. II ×ra. Therefore, the relative brightness of the emission of 11b and the emission of 11a is (D I ×rb) / (D II ×ra)=D I / D II ×(rb / ra).

[0158] For the same light emitted from 31a, its brightness is proportional to its intensity. Therefore, the relative brightness of 11b and 11a caused by the emission of A1 will be (total intensity of light emitted to 11b / total intensity of light emitted to 11a) × (rb / ra).

[0159] As mentioned above, ra and rb are material-related parameters, while the total intensity of light incident on 11b and the total intensity of light incident on 11a are geometry-related parameters.

[0160] exist Figure 6 In the plane shown in (a), the total intensity of the light incident from point A1 to 11b is approximately the total intensity of the light rays with an exit angle of γ. Strictly speaking, the intensity of the light emitted from the light-emitting unit is attenuated to some extent because it passes through the transparent spacer layer before reaching the wavelength conversion layer. However, on the one hand, the transparent spacer layer has good transmittance to the light emitted by the light-emitting unit, so the total attenuation is not significant; on the other hand, the attenuation occurs at various angles and has little impact on the relative brightness changes of adjacent pixels. Therefore, the attenuation caused by the material transmittance in the transparent spacer layer is ignored. The light emitted from the left boundary of angle γ will reach the left boundary point B2 of 11b, and the light emitted from the right boundary will reach the right boundary point C2 of 11b. Although Figure 6 In (a), the angle γ appears small, but in reality, the width of 11b is much wider than shown in the figure. Therefore, the angle γ occupies a significant proportion of the angle in region I. Furthermore, the intensity of the light emitted from A1 is not uniformly distributed across the entire emission angle range, and its intensity is relatively much smaller when the emission angle is large (as will be detailed below). Therefore, the intensity of light exceeding the angle γ can be ignored here. Thus, it can be approximated that of the light emitted by A1 to the right, the total intensity of light with emission angles greater than α reaches 11b, while light with emission angles less than α enters region III and is blocked by the second pixel limiting layer 12.

[0161] Of the light emitted from A1 to the left, the light within the θ range can reach 11a. As mentioned above, although the light beyond the left side of C1 does not contribute to the emission of 11a, its angle is large and its total intensity is small, so it can be ignored. Furthermore, although the light emitted at the small angle corresponding to the right side of B1 does not contribute to the emission of 11a, a large amount of light emitted from the left side of A1 can reach 11a and provide some compensation for the emission. Therefore, it can be approximately considered that the total intensity of light incident from A1 to 11a is roughly the total intensity of all light emitted from A1 to the θ range and to its left, the total intensity of light incident on 11b is the total intensity of light with an exit angle greater than α within the 0-90° range on the right, and the total intensity of light incident on 11a is the total intensity of light with an exit angle of all exit angles within the -90-0° range on the left.

[0162] At this point, the relative brightness of the light incident from A1 to 11b and 11a is (total intensity of light rays with an exit angle greater than α / total intensity of all light rays) × (rb / ra). As mentioned above, the relative brightness should not exceed the critical value of p1, for example, 5%, preferably 3.1%, more preferably 2%, to minimize color bleeding. When p1 is less than 2%, color bleeding can be essentially completely avoided. At this point, (total intensity of light rays with an exit angle greater than α / total intensity of all light rays) × (rb / ra) = p1. Here, when calculating the ratio, all light emitted from both sides can be included, that is, all light emitted from the range of -90° to +90°. This is the same result as the result obtained by calculating only the light emitted from one side from 0-90°.

[0163] In the above formula, the total intensity of light within a certain angular range can be calculated from the relationship curve between the luminous intensity at point A1 and the angle. The total intensity can be obtained by integrating the luminous intensity-angle curve by angle.

[0164] Therefore, after determining p, ra, and rb, the critical value of α can be calculated from the above equation. Furthermore, based on this critical value, the geometry between layers 12, 32, and the transparent spacer can be designed. When B2 is sufficiently to the right (beyond the critical position), not all light rays with an emission angle of α from A1 will reach 11b. Therefore, the ratio of the total intensity of the light rays reaching 11b after wavelength conversion to the brightness of the light rays reaching 11a after wavelength conversion (i.e., relative brightness) will be less than the critical value p1, thus solving the cross-color problem.

[0165] For example, in one implementation scheme Figure 6 In the implementation shown in (a), the critical value p1 of p is set to 5%. Then (total intensity of light rays with an emission angle greater than α / total intensity of all light rays) × (rb / ra) = 5%. The critical position of B2 is obtained according to this value of α. Therefore, when the right end of the sub-pixel is designed to be further to the right than B2, the color mixing problem can be solved.

[0166] More specifically, for example, when the transparent spacer layer is a single-layer material with a uniform refractive index, and rb / ra = 2, the intensity of light rays with an emission angle greater than α accounts for 2.5%. In this case, the corresponding α angle is, for example, 80°. Since the transparent spacer layer is a single-layer material and light propagates in a straight line within it, if the thickness of the transparent spacer layer is d1 = 2 micrometers, then the critical lateral distance from B2 to A1 is 2 micrometers × tan 80° = 11.34 micrometers. This lateral distance is the sum of the width d2 of the top surface of 32 and the portion d42 of the bottom surface of 12 extending beyond the boundary of 32. By designing d2 + d42 to be greater than this critical value, the color bleeding problem can be solved. For example, when the width d2 of 32 is 10 micrometers, the portion d42 of B2 extending beyond A2 needs to be greater than 1.34 micrometers.

[0167] It should be understood that although only the light rays in the paper plane are shown in the figure, since the light rays from A1 outwards from the paper plane are symmetrical from left to right, and the light-emitting unit and wavelength conversion unit also extend in the direction perpendicular to the paper plane, that is, they are also symmetrical in the direction perpendicular to the paper plane, the influence of these light rays that are not in the paper plane on the critical estimation of the relative brightness can be offset or ignored.

[0168] Figure 6 (a) only shows the analysis of color crossing from the left sub-pixel a to the right sub-pixel b. Color crossing from the right sub-pixel to the left sub-pixel can also be analyzed symmetrically. For color crossing from the right to the left sub-pixel, a threshold value p2 can be set according to its color. p2 ≤ 5%, more preferably ≤ 2%. p2 can be equal to p1, as long as there is no obvious color crossing. It should be noted that the relationships of various parameters in this disclosure can be appropriately extended to the case of other sub-pixels, as long as they conform to the principles of this disclosure.

[0169] Specifically, in the direction from the second sub-pixel to the first sub-pixel, the displacement of the orthographic projection on the substrate relative to the top surface of the first sub-pixel's light-emitting unit and the boundary of the first pixel defining layer between the first and second sub-pixels' light-emitting units, and the displacement of the bottom surface of the first wavelength conversion unit and the boundary of the second pixel defining layer between the first and second sub-pixels' wavelength conversion units', relative to the boundary of the first sub-pixel's light-emitting unit and the boundary of the second pixel defining layer's boundary, relative to the boundary of the first and second sub-pixels' light-emitting units', relative to the boundary of the first pixel defining layer's light-emitting unit's boundary, relative to the boundary of the first and second sub-pixels' light-emitting units' boundary, relative to the boundary of the first pixel defining layer's boundary, relative to the boundary of the first pixel defining layer's boundary, relative to the boundary of the first sub-pixel ...

[0170] in,

[0171] Of the light incident from the top surface of the light-emitting unit onto the transparent spacer layer and reaching the top surface of the transparent spacer layer, the intensity percentage of light with an exit angle greater than α2 is less than x2%, where x2% = p2 × (rb / ra), and p2 ≤ 5%.

[0172] Wherein, when the emission angle of light originating from the bottom surface of the transparent spacer layer is α2, the length of the projection of the light path through the transparent spacer layer onto the substrate is less than or equal to d2+d41.

[0173] Color bleeding can be effectively avoided as long as the lateral distances between A1 and B2 or A2 and B1 satisfy the above relationship. In other words, color bleeding can be avoided as long as the lateral distances d2+d41 or d2+d42 satisfy a critical value greater than the projection length of the light path corresponding to the corresponding critical angle α. Optionally, the above lateral distances do not need to be set too large, only slightly larger than the critical value. In other words, the difference between the lateral distance and the critical value can be as small as possible. The difference between the lateral distance and the critical value can be less than or equal to 10μm. Optionally, when the exit angle of light emanating from the bottom surface of the transparent spacer layer is α1, the difference between the projection length of the light path through the transparent spacer layer onto the substrate and d2+d42 is less than or equal to 5μm, less than or equal to 4μm, less than or equal to 3μm, less than or equal to 2μm, less than or equal to 1μm, less than or equal to 0.5μm, or d2+d42 is designed to correspond exactly to the critical exit angle α1. Optionally, when the exit angle is α2, the difference between the length of the projection of the light path passing through the transparent spacer layer onto the substrate and d2+d41 is less than or equal to 5μm, less than or equal to 4μm, less than or equal to 3μm, less than or equal to 2μm, less than or equal to 1μm, less than or equal to 0.5μm, or d2+d41 is designed to correspond exactly to the critical exit angle α2.

[0174] Compared with related technologies, the geometric design of this disclosure does not add light-blocking components between adjacent sub-pixels and provides a lower limit for the spacing between adjacent sub-pixels, thereby maximizing resolution without color mixing.

[0175] Figure 6 (b) schematically illustrates a ratio Figure 6 In a more refined implementation of the schematic diagram of (a), the structure between two adjacent sub-pixels a and b includes a transparent spacer layer with multiple stacked sub-layers. The first sub-pixel a includes a light-emitting unit 31a and a wavelength conversion unit 11a, and the second sub-pixel b includes a light-emitting unit 31b and a wavelength conversion unit 11b. The boundary between the top surface of the light-emitting unit of the first sub-pixel and the first pixel defining layer is A1, and the boundary between the bottom surface of the wavelength conversion unit and the second pixel defining layer is B1. The boundary between the top surface of the light-emitting unit of the second sub-pixel and the first pixel defining layer is A2, and the boundary between the bottom surface of the wavelength conversion unit and the second pixel defining layer is B2. Each of the light-emitting units 31a and 31b includes an anode 311 and a light-emitting material layer 313. They are separated by a first pixel defining layer 32, and the distance between the top surfaces of the light-emitting units 31a and 31b is the width d2 at the top surface of the first pixel defining layer between them, i.e., the width between points A1 and A2. Each light-emitting unit includes an anode and a light-emitting material layer. Above the light-emitting units 31a, 31b and the first pixel defining layer is a transparent spacer layer 2. Figure 6(b) shows a schematic transparent spacer layer with four film layers, including a common cathode 315, a first inorganic layer 211, an organic layer 212, and a second inorganic layer 213. A second pixel defining layer is located between wavelength conversion units 11a and 11b. The distance between the bottom surfaces of wavelength conversion units 11a and 11b is the width d3 at the bottom surface of the second pixel defining layer between them, i.e., the width between points B1 and B2. In the direction from the second sub-pixel to the first sub-pixel (i.e., to the left), the displacement of the orthogonal projection on the substrate relative to the top surface of the first sub-pixel's light-emitting unit and the boundary A1 of the first pixel defining layer between the first and second sub-pixels' light-emitting units, and the orthogonal projection on the substrate relative to the bottom surface of the first wavelength conversion unit and the boundary B2 of the second pixel defining layer between the first and second sub-pixels' wavelength conversion units, is d41. Here, d41 can be negative, meaning B1 can also be to the left of A1. In the direction from the first sub-pixel to the second sub-pixel (i.e., to the right), the displacement on the substrate relative to the orthographic projection of the boundary A2 of the first pixel defining layer between the top surface of the second sub-pixel's light-emitting unit and the light-emitting units of the first and second sub-pixels, and the displacement on the substrate relative to the orthographic projection of the boundary B2 of the second pixel defining layer between the bottom surface of the second wavelength conversion unit and the wavelength conversion units of the first and second sub-pixels, is d42. d41 and d42 are essentially the lateral distance by which the bottom edge of the second pixel defining layer protrudes or recedes relative to the edge of the first pixel defining layer below it. d3 = d2 + d41 + d42.

[0176] This disclosure determines the size of the first pixel definition layer and the second pixel definition layer between adjacent sub-pixels based on the proportion of different emission angles of the light-emitting unit and the brightness change rate of the light-emitting unit by the wavelength conversion unit, thereby controlling the crosstalk between adjacent sub-pixels.

[0177] exist Figure 6 In (b), among the light emitted by the light-emitting unit 11a of sub-pixel a, those rays that can travel from the light-emitting surface of the light-emitting unit 11a through the transparent spacer layer to the wavelength conversion unit 11b may cause crosstalk problems to sub-pixel b. This disclosure controls the amount of such light to a level that does not significantly affect the display of sub-pixel b through structural design.

[0178] The point closest to point A1 on the bottom surface of the wavelength conversion layer 11b and the top surface of the light-emitting unit 31a is its left endpoint B2, which is the right end of the bottom surface of the second pixel defining layer, or the boundary between the bottom surface of the wavelength conversion unit and the second pixel defining layer. For light incident from point A1, light with a smaller exit angle will travel closer in the X direction and will not be able to reach point B2; only light with a larger exit angle can reach point B2. In this disclosure, both the incident angle and the exit angle refer to the angle with the normal, which is in the range of 0-90°, and the incident and exit angles are relative to the interface. In other words, there is a critical exit angle α1. When the exit angle is below the critical angle, the emitted light g1 will not reach the wavelength conversion unit 11b and cause crosstalk, while light g2 and g3 with exit angles equal to or greater than the critical angle may reach the wavelength conversion unit 11b. The dashed lines in the figure represent the correspondence of light rays, but do not indicate that the light rays actually travel in a straight line. Figure 6 (a) The difference is that the light does not travel in a straight line between A1 and B2, but undergoes multiple refractions. These refractions are indicated by dashed lines in the figure, and the specific refraction path is not shown. However, the principles of this disclosure still apply despite the refraction occurring in the transparent spacer layer.

[0179] As mentioned above, unlike the color filter layer, light incident on the wavelength conversion layer can still cause crosstalk even with a large exit angle. The aforementioned critical angle is determined based on the intensity distribution of the light exit angle of the light-emitting unit. By ensuring that the critical angle satisfies the condition that "the proportion of incident light greater than the critical angle is less than a threshold," the crosstalk brightness can be controlled sufficiently to effectively solve the crosstalk problem.

[0180] In this disclosure, the aforementioned threshold is determined through the relationship between the brightness change rates of the wavelength conversion units of the first and second sub-pixels. The display effect of a sub-pixel of a display device is related to its luminous intensity and the human eye's ability to perceive its luminous wavelength, and is comprehensively reflected in its brightness. (Reference) Figure 6(b) When x1% of the light emitted from A1 to the right and reaching the top surface of the transparent spacer layer may reach the adjacent second sub-pixel on the right, the ratio of the brightness of the second sub-pixel due to cross-color emission to the brightness of the light-emitting unit is x1%×rb. The ratio of the brightness of the first sub-pixel caused by the light emitted from A1 to the left to the brightness of the light-emitting unit is ra, where ra and rb are the brightness conversion rates of the first and second sub-pixels to the light-emitting unit, respectively. The brightness ratio of the cross-color emission in the second sub-pixel to the normal emission in the first sub-pixel is x1%×rb / ra, which can be expressed as x1%×(rb / ra). Simulation results show that when this brightness ratio is below 5%, cross-color emission that is perceptible to the human eye is essentially absent. Therefore, when p is the critical value p1, x1%×(rb / ra)=p1, i.e., x1%=p1×(ra / rb). The critical value p1 can be more preferably below 3.1%, and even more preferably below 2%.

[0181] It should be noted that, with Figure 6 The case of a single-material transparent spacer layer in (a) is different. Figure 6 (b) Due to the overlapping of film layers with different refractive indices in the transparent spacer layer, total internal reflection occurs, causing some light to fail to reach the wavelength conversion unit. In this case, when calculating the light intensity reaching the wavelength conversion unit of the two sub-pixels, light that cannot reach the top surface of the transparent spacer layer is excluded because it does not cause cross-contamination. The scheme disclosed herein only considers the proportion of light intensity in the light incident from the top surface of the light-emitting unit onto the transparent spacer layer and capable of reaching the top surface of the transparent spacer layer. When total internal reflection is possible in the transparent spacer layer, the totally reflected portion must be removed. For example, when the transparent spacer layer contains a sublayer with a refractive index of 1.8 and an adjacent sublayer with a refractive index of 1.5 in the light-emitting direction, light incident from the sublayer with a refractive index of 1.8 to the sublayer with a refractive index of 1.5 at an angle greater than approximately 52° will be totally internally reflected. In this case, the corresponding critical angle can be calculated based on the total light intensity of the initial incident light in the range of 0 to 52° in that layer. Light intensity with an incident angle greater than 52° will not affect the wavelength conversion layer because it does not reach the top surface of the transparent spacer layer, and therefore is not considered in the calculation of critical geometric parameters.

[0182] Therefore, if the intensity percentage of light traveling from point A1 to point B2 is limited to below the aforementioned critical value x1%, the color mixing problem can be effectively eliminated. In this case, when light with an exit angle of α1 incident from the interface between the transparent spacer layer and the light-emitting unit exits at its top surface, the lateral distance traversed from the incident point to the exit point needs to be less than or equal to d2 + d42, i.e., the sum of the distances from A1 to A2 and from A2 to B2. It can be understood that if the edge of the second pixel defining layer is recessed relative to the edge of the first pixel defining layer, d42 can also be a negative value. Specifically, the intensity percentage of light with an exit angle greater than α1 among the light emitted by the light-emitting unit incident on the interface is below x1%.

[0183] In summary, the design concept of this disclosure is as follows: First, determine the change coefficient of the wavelength conversion unit (or transparent color resist unit) of two adjacent sub-pixels on the brightness of the light-emitting unit. Second, consider the ratio of light reaching adjacent sub-pixels to light reaching the current sub-pixel from the light-emitting unit of a sub-pixel, which would result in sufficient brightness for the adjacent sub-pixels to display crosstalk. In this process, the aforementioned brightness change coefficient is taken into account, and the brightness ratio sufficient to display crosstalk is set as the simulated critical ratio p. Finally, calculate the upper limit x% of the proportion of light reaching adjacent sub-pixels that should not be exceeded. Third, consider the critical emission angle α at the bottom surface of the transparent spacer layer corresponding to these proportions of light, and stipulate that the amount of light with an emission angle greater than α is the aforementioned upper limit x%. That is, calculate a lower limit for the emission angle, and it is necessary to avoid light with an emission angle less than this lower limit from reaching adjacent sub-pixels. Fourth, based on this critical emission angle, calculate the lower limit of the lateral distance d2+d4 between the starting and ending points of the light path. In this way, as long as the distance between d2 and d4 is large enough (greater than the lateral distance between the start and end points of the light path corresponding to the critical angle α), it can be guaranteed that light with an emission angle less than α will not enter the adjacent sub-pixels. This ensures that only less than x% of the light enters the adjacent sub-pixels. Furthermore, it ensures that after the brightness conversion by the wavelength conversion unit, the brightness generated in the adjacent sub-pixels is less than the critical ratio of the brightness generated in the light-emitting sub-pixels, thus preventing color crosstalk that affects actual viewing.

[0184] For the non-standard shaped first pixel defining layer, second pixel defining layer, light-emitting unit, wavelength conversion unit, and transparent spacer layer actually prepared, they can be fitted to a standard pattern according to the above principles, and their geometric characteristics can be checked to see if they conform to this disclosure, that is, whether they can achieve the goal of enabling a limited proportion of light to reach adjacent sub-pixels, and whether the relative brightness limit is met after conversion. It should be understood that although the following figures are all drawn based on standard patterns, they also include technical solutions that conform to the above principles.

[0185] The critical exit angle α corresponding to the proportion of light intensity exceeding a certain value in the light emitted by the light-emitting unit incident on the interface can be measured experimentally or calculated through modeling. The inventors discovered that the light intensity entering the transparent spacer layer from the light-emitting unit at its interface with the transparent spacer layer can vary with the angle. For example, the light intensity is highest at an exit angle of 0° (i.e., in the normal direction), while the intensity approaches zero when the exit angle is close to 90°. Moreover, the relationship between intensity and angle is not necessarily monotonically increasing or decreasing. Figure 7 An exemplary emission angle-light intensity curve is shown. The intensity drops to a minimum around 40 degrees, then rises again, reaches a maximum around 60 degrees, and then decreases again. The aforementioned threshold can be calculated based on the area under the curve in the emission angle-light intensity curve. Therefore, the critical angle can be determined from the threshold. The emission angle-light intensity curve can be measured experimentally or calculated using modeling. Figure 7 The light intensity distribution at angles above 60° shown in the table below represents the proportion of light intensity in the light field distribution.

[0186] Angle (°) 60 65 70 75 80 85 Light intensity percentage (%) 21.8 15.6 11.0 6.45 2.4 0.6

[0187] Figure 7 The light field distribution shown in the table above is only one example. Specific light field distributions can be compared with... Figure 7 The differences are shown.

[0188] Through the above structural design, the color crosstalk effect of the first sub-pixel on the second sub-pixel is accurately controlled.

[0189] same, Figure 6 (b) The dimensions of the encapsulation structure layer, the first pixel limiting layer, and the second pixel limiting layer should also ensure that the cross-color influence of the second sub-pixel on the first sub-pixel is controlled. Therefore, when light with an emission angle of α2 exits from its top surface, the lateral distance between the emission point and the incident point is no greater than d2 + d41. In the light emitted by the light-emitting unit incident on the interface, the intensity proportion of light with an emission angle greater than α2 is less than x2%, where x2% = p2 × (rb / ra). The critical value p2 is selected as ≤5%.

[0190] Note that the aforementioned conditions only specify the sum of d2 and d42 or the sum of d2 and d41, without specifying the proportion of d2 in d2+d42. Typically, the size of the first pixel limiting layer is designed first, followed by the size of the second pixel limiting layer. In other words, d2 is determined first, and then d41 and d42 are determined based on d2. Figure 6In the embodiment shown in (b), the bottom of the second pixel defining layer is wider than the top of the first pixel defining layer, and therefore d41 and d42 are positive values. However, in some embodiments, d41 and d42 may also be negative values, corresponding to the case where the bottom of the second pixel defining layer is narrower than the top of the first pixel defining layer. In other embodiments, d41 and d42 may be substantially 0.

[0191] In some embodiments, for ease of fabrication, the second pixel defining layer is centered and aligned with the first pixel defining layer, thus d41 and d42 are equal. It is understood that when ra is not equal to rb, the critical values ​​for d41 and d42 should satisfy the condition that the intensity proportion of light with an emission angle above α1 is less than x1%, and the intensity proportion of light with an emission angle above α2 is less than x2%. In this case, the larger of the critical values ​​for d41 and d42 can be used simultaneously in the sub-pixels on both sides to achieve a symmetrical design. For example, when ra > rb, the brightness change rate of the wavelength conversion material in the first sub-pixel is higher. In this case, x1 > x2, meaning the upper limit of the proportion of light with an emission angle above α1 can be greater than the upper limit of the proportion of light with an emission angle above α2, i.e., α1 < α2. Accordingly, the critical value of d41 is larger than the critical value of d42. At this point, d42 can also be set according to the critical value of d41, so that the lateral propagation distance of the optical path meets the requirement of preventing the second sub-pixel from crossing colors to the first sub-pixel, and at the same time, the lateral propagation distance of the optical path also naturally meets the requirement of preventing the first sub-pixel from crossing colors to the second sub-pixel.

[0192] Of course, this disclosure can also design different sub-pixel geometric dimensions based on the specific parameters of two adjacent sub-pixels. If the axisymmetric shape of the second pixel limiting layer and the first pixel limiting layer in the cross section is not considered, then d41 and d42 may not be equal.

[0193] In one implementation, the second pixel defining layer is centered and aligned with the first pixel defining layer, and its bottom width is equal to the top width of the first pixel defining layer, i.e., d41=d42=0. This facilitates the fabrication of the film layer using the same mask or other devices.

[0194] In one implementation, considering that there may be a misalignment of 1-5 micrometers in actual production, the size range can optionally be widened to |d41| ≤ 5μm, ≤ 4μm, ≤ 3μm, ≤ 2μm, ≤ 1μm. Similarly, |d42| ≤ 5μm, ≤ 4μm, ≤ 3μm, ≤ 2μm, ≤ 1μm.

[0195] Once the critical angle is determined, the interrelationships between the various dimensions can be determined by calculating the optical paths within the transparent spacer layer. In other words, when the display panel is fabricated according to the obtained dimensional relationships, the display panel will not exhibit significant color bleeding issues. At this point, the structural design simplifies to calculating the independent optical paths within the transparent spacer layer. Figure 8 A schematic optical path in an exemplary transparent spacer layer is shown. The four layers, from bottom to top, are L1 to L4. For example, L1 can be an ITO cathode layer, upon which a first inorganic layer, an organic layer, a second inorganic layer, etc., are sequentially covered. Their refractive indices are n1 to n4, respectively. A ray incident from the bottom of the transparent cathode at an exit angle θ1 travels towards the top of the transparent spacer layer, changing its angle according to the refractive index formula at each interface it passes: n1sinθ1 = n2sinθ2 = n3sinθ3 = n4sinθ4. Based on these angles, the relationship between the lateral and longitudinal optical paths can be further calculated. The lateral optical path d = L1tanθ1 + L2tanθ2 + L3tanθ3 + L4tanθ4. Therefore, by defining θ1 as α1 determined by x1 or α2 determined by x2, the geometric relationship between the first and second sub-pixels can be calculated, thus completing the structural design.

[0196] Therefore, when using a specific transparent spacer layer, the required lateral spacing between subpixels can be obtained according to the relationships disclosed herein. Conversely, when a certain resolution is required, the transparent spacer layer and its specific sublayers can be selected according to the relationships disclosed herein.

[0197] In one embodiment, the thickness of the transparent spacer layer is d1, and the transparent spacer layer comprises m sublayers stacked from bottom to top, wherein the thickness and refractive index of the i-th sublayer are L and L, respectively. i and n i i is from 1 to m.

[0198] All parameters satisfy:

[0199]

[0200] Where i is an integer from 1 to m, n i sinθ 1i is a constant and θ 11 =α1.

[0201] In other words, the lateral travel distance of the light path is the sum of the travel distances in each sublayer. The travel distance in each sublayer is related to the exit angle and sublayer thickness at each incident interface. The exit angle at each incident interface is related to the refractive index of that sublayer and the previous sublayer. When the exit angle α when the light enters the bottom interface of the first sublayer is determined, d1, d2, and d4 can be calculated in the manner described above. For example, for the exit angle α1, d2 + d42 can be calculated as above; for the exit angle α2, d2 + d41 can be calculated similarly; for the exit angle α3 below, d5 + d43 can be calculated similarly; and so on.

[0202] It should also be noted that when a transparent metallic cathode is present at the bottom of the transparent spacer layer, although the extremely thin transparent metallic cathode is transparent to light, the refraction behavior of light within it may not be suitable for characterization using conventional refractive indices. However, the thickness of the transparent metallic cathode is much smaller than that of the inorganic / organic encapsulation layer above it. Typically, the thickness of the transparent metallic cathode is usually at most tens of nanometers, while the scale of the encapsulation layer above it is on the micrometer scale. Therefore, in the calculations of the above formulas in this disclosure, the presence of the transparent metallic cathode can be ignored. That is, the thickness of the transparent metallic cathode and the lateral propagation of light within it are not taken into account. In this case, the light emission angle θ 11 θ 12 The measurement begins from the top surface of the transparent metallic cathode, which serves as the interface. However, for cathodes with greater thickness, such as ITO electrodes, the propagation of light within them should not be ignored.

[0203] In one embodiment, the array of sub-pixels further includes a third sub-pixel, adjacent to the first sub-pixel. The third sub-pixel includes a light-emitting unit in the light-emitting layer and a transparent color-resisting unit in the wavelength conversion layer. The light-emitting unit and the transparent color-resisting unit are stacked and separated by the transparent spacer layer.

[0204] The light-emitting units of the first sub-pixel and the third sub-pixel are separated by the first pixel defining layer in the light-emitting layer, and the top surface spacing is d5.

[0205] The transparent color resist unit does not perform wavelength conversion on the light emitted by the light-emitting unit and has a brightness change rate of rc. The wavelength conversion unit of the first sub-pixel and the transparent color resist unit of the third sub-pixel are separated by the second pixel limiting layer in the wavelength conversion layer.

[0206] In the direction from the third sub-pixel to the first sub-pixel, the displacement of the orthographic projection on the substrate relative to the top surface of the light-emitting unit of the first sub-pixel and the boundary of the first pixel defining layer between the light-emitting units of the first and third sub-pixels, and the displacement of the bottom surface of the first wavelength conversion unit and the boundary of the second pixel defining layer between the wavelength conversion unit of the first sub-pixel and the transparent color resist unit of the third sub-pixel, is d43.

[0207] in,

[0208] Of the light incident from the top surface of the light-emitting unit onto the transparent spacer layer and reaching the top surface of the transparent spacer layer, the intensity of light with an exit angle greater than α3 accounts for less than x3%, where x3% = p3 × (rc / ra), and p3 ≤ 5%.

[0209] Wherein, when the emission angle of light originating from the bottom surface of the transparent spacer layer is α3, the length of the projection of the light path through the transparent spacer layer onto the substrate is less than or equal to d5+d43.

[0210] As described above, the wavelength conversion layer of this disclosure may also include transparent color resist units. Subpixels with transparent color resist units are used to ensure that the light emitted by the light-emitting unit is emitted directly without wavelength conversion. For a subpixel with a wavelength conversion unit and an adjacent subpixel with a transparent color resist unit, the cross-coloring between them is as follows.

[0211] Figure 9 The schematic illustration shows the structure between two adjacent sub-pixels c and a in one embodiment of the present disclosure. The first sub-pixel a includes a light-emitting unit 31a and a wavelength conversion unit 11a, and the third sub-pixel c includes a light-emitting unit 31c and a wavelength conversion unit 11c. Figure 9 The transparent spacer layer, light-emitting unit, first pixel defining layer, and second pixel defining layer are similar to the components in the text. Figure 6 .

[0212] and Figure 6 (f) The difference is that the light from point A3 to point B4 of the first sub-pixel enters the transparent color resist unit 11c. Since the transparent color resist unit 11c does not have wavelength-converting particles, even if it contains scattering particles, the light from point A3 to point B4 of the first sub-pixel will not significantly produce light emission on the front of the display panel. In other words, the crosstalk level from the first sub-pixel to the third sub-pixel without wavelength conversion can be ignored and does not need to be limited by special geometric parameters. In this case, the distance d44 can also be left undefined. Of course, d44 can also be defined based on the relative brightness concept of this invention.

[0213] However, the light rays from point A4 to point B3 in the third sub-pixel still pose a risk of color crosstalk, which needs to be controlled using the principles of this disclosure. At this time, the transparent color resist unit does not perform wavelength conversion on the light emitted by the light-emitting unit, but its brightness still changes due to the material's brightness change rate, where the brightness change rate is rc. rc is always a value less than 100%. Accordingly, when the aforementioned relative brightness threshold value p is selected, the critical emission angle α3 corresponding to the critical leakage intensity ratio from the light-emitting unit 31c of the third sub-pixel to the wavelength conversion unit 11a of the first sub-pixel can be calculated from p, ra, and rc. The preferred range of the relative brightness threshold value for preventing color crosstalk is the same as described above.

[0214] Typically, the width of the top surface of the pixel-bound layer is equal between each sub-pixel because the light-emitting units are usually of the same size and uniformly distributed. In other words, the geometric parameters can be designed as d5=d2.

[0215] Based on the aforementioned method, the specific geometric structure of each layer in a display panel with three color sub-pixels can be designed.

[0216] In one implementation, the light-emitting unit emits blue light, the third sub-pixel contains a transparent color resist unit and is a blue sub-pixel, the first sub-pixel is a red sub-pixel, and the second sub-pixel is a green sub-pixel, which are respectively red and green sub-pixels, thereby enabling RGB color display.

[0217] In one implementation, the brightness change rate of the transparent color resist unit is [60%, 85%].

[0218] In one implementation, ra is in the range of [110%, 180%], and rb is in the range of [25%, 70%]. The rate of change in brightness is related to parameters such as the emission wavelength, the wavelength after conversion, and the external quantum efficiency of the photoluminescent material, and varies considerably. Typically, the rate of change in brightness from blue to green light is in the range of 25% to 70%, and the rate of change in brightness from blue to red light is in the range of 110% to 180%. Based on these ranges, x1 and x2 can be calculated, then α1 and α2 can be calculated, and then the required d2+d41 and d2+d42 can be calculated.

[0219] As examples, in cadmium selenide-based quantum dots, the brightness change rate of red quantum dots can be about 40%, and that of green quantum dots can be about 170%. In indium phosphide-based quantum dots, the brightness change rate of red quantum dots can be about 23%, and that of green quantum dots can be about 110%.

[0220] In one implementation, for example, the brightness change rate of the red subpixel can be approximately 120%, the brightness change rate of the green subpixel can be approximately 60%, and the brightness change rate of the transparent color resist unit or light scattering unit can be approximately 80%. All critical p values ​​are taken as 3%. Since there is no wavelength conversion unit in the blue subpixel, no photoluminescence occurs, and color mixing from the red and green subpixels to the blue subpixel is unlikely to occur. However, among adjacent red, green, and blue subpixels, the color mixing from the green subpixel to the red subpixel is most pronounced because the red subpixel has a high brightness change rate and the green subpixel has the lowest brightness change rate. In this case, assuming the red subpixel is the first subpixel and the green subpixel is the second subpixel, then x1% is approximately 3% × (120% / 60%) = 6%, and x2% is approximately 3% × (60% / 120%) = 1.5%. Correspondingly, for example, according to the previous table, the angle corresponding to α1 is approximately 76°, and the angle corresponding to α2 is approximately 82°. In this case, the minimum value of d41 will be greater than the minimum value of d42. In this scenario, the lateral distance between the top surface of the light-emitting unit of all sub-pixels and the bottom surface of the wavelength conversion unit or transparent color resist unit of the adjacent sub-pixel can be set to d2+d41, corresponding to 82°. In other words, as long as the emission of green sub-pixels does not cause significant color crosstalk to red sub-pixels, other color crosstalk can be avoided.

[0221] It should be understood that the above example parameters are for illustrative purposes only and not for limiting this disclosure.

[0222] In implementations, the design of this disclosure can also be used for adjacent sub-pixels of the same color. For example, in Figure 1 In the Y direction, adjacent sub-pixels of the same color are arranged. Although crosstalk between sub-pixels of the same color does not cause color changes, it still affects the display. Figure 10 It shows in Figure 2 The cross-section in the YZ plane. Since adjacent sub-pixels a1 and a2 are the same color, d45 and d46 can be equal. Furthermore, this is equivalent to equal conversion rates. Moreover, for the case of the second sub-pixel with a wavelength conversion unit in the Y direction, the conversion rates of adjacent sub-pixels are also equal. Therefore, the critical light intensity percentage is equal for both the first and second sub-pixels. When adjacent sub-pixels are the same color, this percentage can be chosen to be slightly larger, for example, 5%, but it can also be chosen from the aforementioned range up to p and the preferred range. The parameters between the first and second sub-pixels are the same. As for the third sub-pixel, for example, with a transparent color resist unit, since crosstalk is not significant, its geometry is not limited, but it is preferable that it has the same size as the first and second sub-pixels.

[0223] In one embodiment, the wavelength conversion unit comprises quantum dots. In other words, the wavelength conversion unit can be a quantum dot wavelength conversion unit. More preferably, the light-emitting unit is an OLED. Thus, a QD-OLED display panel is formed.

[0224] In one embodiment, the transparent spacer layer comprises, from bottom to top, a first inorganic layer, an organic layer, and a second inorganic layer. The inorganic-organic-inorganic transparent spacer layer can be an encapsulation layer for encapsulating the light-emitting layer, providing good overall mechanical properties and protection against external elements, and serving as a substrate for the subsequent fabrication of a second pixel defining layer, wavelength conversion layer, or transparent layer, or for preparing a cell to be paired with a separately fabricated wavelength conversion layer.

[0225] In one implementation, the first inorganic layer can be a SiNx layer, and the second inorganic layer can be a SiONx layer or an Al2O3 layer. Sandwiching an organic layer between such a first and second inorganic layer can achieve good encapsulation. The material and thickness of the inorganic layer can be appropriately adjusted, taking into account protection, thickness, and its own strength.

[0226] Organic layers typically have a lower refractive index than the inorganic layers above and below them, causing light to travel at large angles and resulting in a long optical path length. Reducing the thickness of the organic layer helps to decrease the distance between adjacent sub-pixels, thereby improving resolution.

[0227] As described above, typically, a transparent cathode serves as a common electrode covering the first pixel defining layer. It should be understood that electron injection layers, electron transport layers, hole blocking layers, and other films may also exist between the transparent cathode and the light-emitting material layer of the light-emitting unit. If these films are formed entirely on the first pixel defining layer, they can also serve as part of a transparent spacer layer. If these films are formed between the first pixel defining layers, they belong to a single light-emitting unit.

[0228] Transparent cathodes can use materials commonly found in related technologies. As mentioned above, the thickness of a metallic transparent cathode is much smaller than that of the transparent spacer layer, therefore its presence can be ignored in the aforementioned formula for calculating the lateral optical path distance based on the refractive index and film thickness.

[0229] In one embodiment, the thickness of the organic layer is in the range of 4 to 8 μm. Such a thickness is lower than the conventional thickness in related technologies, which is beneficial for reducing optical path. An organic layer of this thickness can be formed, for example, by inkjet printing. At this thickness, according to the principles of this disclosure, a display panel with no color bleeding and a higher resolution can be obtained.

[0230] In one embodiment, the thickness of the organic layer is in the range of 0.3 to 0.6 μm. This thickness is significantly reduced compared to related technologies, which is beneficial for substantially reducing optical path length and significantly improving resolution. Such a thin organic layer can be prepared, for example, by molecular layer deposition.

[0231] For example, in one exemplary embodiment, the first inorganic layer is SiN with a thickness ranging from 0.6 to 1.2 μm, the organic layer is an organic filler layer with a thickness ranging from 4 to 8 μm, and the second inorganic layer is SiON with a thickness ranging from 0.6 to 1.2 μm.

[0232] For example, in one exemplary embodiment, the first inorganic layer is SiN with a thickness ranging from 0.4 to 0.7 μm, the organic layer is an organic layer with a thickness ranging from 0.3 to 0.6 μm, and the second inorganic layer is Al2O3 with a thickness ranging from 0.7 to 1.3 μm.

[0233] This disclosure utilizes the bottom of the second pixel defining layer to define the bottom surface of the wavelength conversion unit or the transparent color resist unit. Figure 11 Several common schematic shapes for second pixel defining layers are shown, including substantially regular trapezoidal, substantially rectangular, and substantially inverted trapezoidal. A regular trapezoid indicates that the side closer to the substrate is longer, while an inverted trapezoid indicates that the side closer to the light-emitting side is longer. Of course, the second pixel defining layer can also be asymmetrical, but from a fabrication convenience perspective, a symmetrical second pixel defining layer is preferred.

[0234] For the second pixel defining layer with these shapes, the boundary of its interface with the transparent spacer layer is the boundary of its interface with the wavelength conversion units or transparent color resist units on both sides, and defines their bottom surfaces.

[0235] In one implementation, the top surface width of the second pixel defining layer is smaller than its bottom surface width. The light-emitting surface of the wavelength conversion layer between the second pixel defining layers is larger than the light-incident surface, which is beneficial for display.

[0236] In one embodiment, the second pixel defining layer of this disclosure may include a main body portion and a cladding layer on the sidewall of the main body. The additional cladding layer on the main body portion can provide various advantages to the wavelength conversion unit.

[0237] Figure 12 A schematic diagram of a second pixel-defining layer with a sidewall cladding is shown.

[0238] Wavelength conversion layers, such as QD wavelength conversion layers, are often fabricated using inkjet printing. In the On-EL approach, a low-temperature curing second pixel defining layer pattern needs to be fabricated on the encapsulation layer. This is because the light-emitting units are not resistant to high temperatures; when the temperature exceeds 100°C, problems such as reduced luminous efficiency and lifespan occur. However, the low-temperature curing second pixel defining layer material still has a large number of gaps and pores inside due to its low curing temperature, making it easy for ink to penetrate from one pixel to another, causing color mixing. Furthermore, due to ink penetration, the second pixel defining layer undergoes a swelling effect, widening overall and reducing the pixel aperture ratio. To prevent the swelling effect of the second pixel defining layer and the penetration of ink into adjacent pixels, an ink penetration protection layer can be set on the sidewall of the original second pixel defining layer. In this case, the second pixel defining layer includes a main body and an ink penetration protection layer disposed on its side.

[0239] The coating can also be a reflective layer, including reflective materials. The coating can also be a light-absorbing layer, including light-absorbing materials (e.g., metallic molybdenum; or a resin doped with a black pigment, wherein the black pigment can be one or more of aniline black, perylene black, titanium black, carbon black, and metal oxides). The presence of a reflective layer allows unconverted and converted light incident on the sidewalls of the second pixel defining layer to re-enter the wavelength conversion unit, enhancing light extraction efficiency. When reflective or light-absorbing materials form a lateral extension as described below on the top surface of the transparent spacer layer, they can block light.

[0240] Preferably, the coating material is a metal layer. The metal layer has a relatively dense structure, which can block solvents and also has a reflective effect. More preferably, the metal used can be, but is not limited to, Al, Ti / Al / Ti, Mo, etc., which have excellent density in blocking ink solvents and reflective or light-absorbing properties.

[0241] In one embodiment, the overlay has a laterally extending portion at the bottom that covers the surface of the transparent spacer layer and extends away from the main body.

[0242] Figure 13A schematic diagram of a structure with an extended coating at the bottom is shown. It can be seen that the ink-permeable protective layer, which can also be a reflective layer, widens the second pixel-defining layer at the bottom. This design has two advantages. First, without this "L"-shaped coating, if the bottom width of the second pixel-defining layer is increased to avoid color bleeding, the upper part of the second pixel-defining layer will also widen, resulting in a relatively smaller light-emitting area or volume of the wavelength conversion layer. This L-shaped coating allows for a larger volume of the wavelength conversion layer with the same incident light surface, enabling more efficient wavelength conversion and a relatively larger light-emitting area without affecting resolution. Second, if this L-shaped coating is an ink-permeable protective layer, it will enhance the protection of the bottom of the main body, making it more difficult for ink to penetrate the relatively weak bottom.

[0243] In a more preferred embodiment, the main body has an undercut, and the covering layer not only covers the sidewalls but also the top surface of the transparent spacer layer at the undercut, such as... Figure 13 As shown in the figure on the right.

[0244] Undercutting refers to the bottom of the second pixel defining layer being recessed relative to its top, where the bottom is closer to the substrate and the top is further away from the substrate. Typically, an inverted trapezoidal shape exhibits undercutting. While a trapezoidal cross-section is ideal, limitations in the material and manufacturing process of the second pixel defining layer often result in deviations from a standard trapezoidal cross-section in actual products. The apex of an inverted trapezoid is often not sharp but rounded, sometimes even forming the aforementioned "mushroom-shaped" cross-section, with rounded upper apex corners and a potentially reduced undercut depth at the root. It should be noted that, where process allows, deviations from a trapezoidal shape should be avoided as much as possible; a standard trapezoidal shape is more ideal.

[0245] The advantage of the L-shaped ink penetration protective layer set in the undercut is that it can be easily prepared on the low-temperature curing second pixel defining layer by sputtering followed by dry etching. Specifically, the second pixel defining layer is prepared by the following method: photocuring to obtain a body with an undercut, sputtering to deposit a protective layer, and then removing the protective layer on the top surface of the body and the protective layer outside the undercut area by dry etching.

[0246] Figure 14SEM images of the metallic ink penetration protective layers on the undercut and sidewalls are shown. In these images, the metallic ink penetration protective layers are all aluminum layers, with thicknesses of 2000 Å, 3000 Å, 4000 Å, and 6000 Å, respectively, in Figures (a)-(d). It can be seen that the Al thickness, ranging from 2000 to 6000 Å, results in different reflective metallic morphologies and masking ranges on the sidewalls of the second pixel-defining layer after dry etching. Following the principle of maximizing coverage to prevent ink penetration, an Al thickness of 2000-4000 Å is suitable, with other metals adhering to the same range.

[0247] A variety of metals can be used. The reflectivity of visible light, from highest to lowest, is: Ti / Al / Ti > Al > Mo. However, since Al is easily oxidized to Al2O3, which reduces the reflectivity, Ti / Al / Ti or Ti metal is preferred.

[0248] Preferably, the undercut depth ranges from [4 micrometers to 9 micrometers]. The undercut depth is the difference between the projected distances of the top and bottom edges on the substrate, such as... Figure 13 The distance u between the arrows in the right figure. This undercut depth can be formed by photopolymerization. When the main body is substantially inverted trapezoidal, the angle between its side surface and bottom surface is preferably between 95° and 140°. This angle maintains the strength of the main body and leaves adequate space for the ink penetration protective layer at the undercut.

[0249] The display panel fabrication process can include a cell-mount method and an on-EL method. The cell-mount method involves separately forming the light-emitting layer and the wavelength conversion layer, and then assembling them into a cell. The on-EL method involves fabricating the wavelength conversion layer layer by layer on top of the light-emitting layer. The display panel disclosed herein can utilize both of these fabrication processes simultaneously. Furthermore, from the fabrication process of the wavelength conversion unit / transparent color resist unit, it can include inkjet printing and photolithography.

[0250] The above descriptions in this disclosure are all based on an ideal flat shape. For example, the shapes in the cross-sectional views are all rectangular or trapezoidal. Ideally, the top surface of the first pixel defining layer is a plane, and the top surface of the light-emitting unit between them is a plane flush with it; the bottom surface of the second pixel defining layer is a plane, and the bottom surface of the wavelength conversion unit between them is a plane flush with it; the bottom and top surfaces of the transparent spacer layer are also correspondingly planes. Furthermore, the sidewalls of these structures are also flat. In actual production, each of the above surfaces may not be an ideal plane, and the sidewalls of these structures may not be flat. However, these surfaces should not have excessive undulations. When these surfaces have only minor undulations relative to the ideal shape, the aforementioned parameters are determined by fitting their surfaces to a plane.

[0251] This disclosure also provides a display panel including a color filter layer. The display panel of this disclosure may further include a color filter layer to provide better color display performance. The color filter layer is disposed on a wavelength conversion layer. For example, red, green, and blue filter units are disposed at corresponding positions of red, green, and blue sub-pixels.

[0252] Figure 15 A schematic diagram of one embodiment of the QD-OLED display panel of this disclosure, which also includes a color filter layer, is shown. A color filter layer 6 and an outer protective encapsulation layer 5 are also covered on the wavelength conversion layer 3. The color filter layer 6 may include a black matrix BM and various color filters defined by BM. 31 is an OLED light-emitting unit, 11R and 11G are red and green wavelength conversion units, 11B is a transparent color resist unit, and 61R, 61G, and 61B are red, green, and blue color filters, respectively.

[0253] Figure 15 Only a schematic basic structure is shown. Specifically, the transparent spacer layer 2 may include an encapsulation layer for the light-emitting layer and an encapsulation layer for the wavelength conversion layer, and may also include a filler layer and a support pillar structure between the light-emitting layer and the wavelength conversion layer. For the wavelength conversion layer, the encapsulation layer facilitates its assembly into a cell. Figure 15 This is intended only to illustrate the relative positions of the components and does not impose any restrictions on the specific shape and details of each part.

[0254] Figure 16 An embodiment of the light-emitting layer structure is shown. The figure shows a partial schematic diagram containing three complete OLED light-emitting units and four PDL-1s. A buffer layer BUF is provided on the substrate BS. On the buffer layer, a TFT unit is configured for each sub-pixel. The TFT unit includes a source S, a drain D, a gate G, and an active layer ACT. A first gate insulating layer GI1 is located below the gate and between it and the active layer, and a second gate insulating layer GI2 covers the gate around and above it. An interlayer dielectric layer ILD and a planarization layer PLN are sequentially disposed above the second gate insulating layer. Enable signal lines Ce1 and Ce2 are also disposed between the second insulating layer and the interlayer dielectric layer. On the planarization layer, light-emitting units are formed between the first pixel defining layers PDL-1. The light-emitting unit includes an anode AD, an organic light-emitting portion EL, and a cathode CD from bottom to top. The anode is connected to the drain of the TFT, and the cathode is a common electrode. Above the cathode, there is a first encapsulation layer Encap-1. The first encapsulation layer is located on the side of the light-emitting layer closer to the wavelength conversion layer. Figure 2As exemplarily shown, PDL-1 is a wall with a trapezoidal cross-section. It should be understood that it forms a grid on the array substrate and defines a number of spaces for accommodating the light-emitting units. The structure of the OLED light-emitting unit as described above is known in the art, and it includes an anode, an organic light-emitting layer, a cathode, etc. In Figure 17, the anode AD of the light-emitting unit can be a reflective anode, reflecting the light emitted by the OLED towards the top surface to increase the light extraction efficiency. Furthermore, unlike multi-color OLED arrays, the light-emitting layer of this disclosure contains only a single-color light-emitting material layer, so it can be formed using an open mask over the entire surface, without the need for forming each sub-pixel individually using, for example, a fine metal mask. The projection of the TFT on the substrate can overlap with both PDL-1 and the light-emitting units. That is, the TFT can also be partially located under PDL-1 and partially located under the reflective anode.

[0255] This disclosure provides a method for preparing the above-mentioned display panel, wherein the second pixel defining layer is obtained through the following steps:

[0256] Obtain the main body with an undercut;

[0257] A coating layer is sputtered and deposited on the surfaces of the transparent spacer layer and the main body.

[0258] The coating on the top surface of the main body and the portion of the coating on the transparent spacer layer not covered by the top surface of the main body are removed by dry etching, while the coating on the sidewalls of the main body and the undercut are retained.

[0259] For display panels with undercuts, the above sputtering-dry etching method can easily achieve results such as... Figure 13 The right figure schematically illustrates the "L"-shaped coating. In one embodiment, metals such as Al, Ti / Al / Ti, and Mo are deposited at room temperature on the second pixel defining layer by sputtering, followed by vertical etching using dry etching. The inverted trapezoidal sidewalls provide effective shielding, leaving the metal on the sidewalls intact, while the metal at the top of the inverted trapezoid and within the pixel is etched away. The absence of metal at the top of the inverted trapezoid prevents reflection of ambient light. The top of the second pixel defining layer is then bombarded with hydrogen fluoride plasma to surface-modify it, giving it hydrophobic and oleophobic surface properties for subsequent printing processes.

[0260] In one embodiment, the undercut body is obtained by low-temperature curing of a black material. In the On-EL fabrication process, the wavelength conversion layer is formed directly on the substrate of the light-emitting layer and the transparent spacer layer. Therefore, it is advantageous to use a low-temperature curing second pixel defining layer to prevent damage to the underlying light-emitting unit due to high temperatures. However, due to the low curing temperature, the low-temperature curing material still has a large number of gaps and pores inside, which can cause ink to easily penetrate during inkjet printing, causing color mixing as ink seeps from one pixel into another. Furthermore, the second pixel defining layer material undergoes a swelling effect, widening overall and resulting in a decrease in pixel aperture ratio.

[0261] To address this issue, using a low-temperature curing black material is particularly advantageous because, during the curing process, the bottom layer cures less effectively due to the black material blocking light, thus naturally forming an undercut. This undercut facilitates the formation of an L-shaped coating, and once formed, the L-shaped coating effectively prevents ink penetration.

[0262] Therefore, using a low-temperature curing black material to obtain a body with an undercut notch not only protects the light-emitting unit but also allows for the convenient fabrication of an L-shaped overlay to overcome porosity issues. Furthermore, the edge of the L-shaped overlay in the undercut, i.e., the boundary of the wavelength conversion unit, can be easily defined in a dry etching process by the top width of the second pixel defining layer itself, without the need for high-precision masking or other patterning methods. This avoids the need for... Figure 13 The problem of difficulty in controlling the lateral extension distance of the L-shaped coating.

[0263] In one embodiment, the transparent spacer layer comprises an organic layer, which is prepared by molecular layer deposition. Compared to coating or inkjet printing, molecular layer deposition allows for a much thinner organic layer. Since organic materials typically have a low refractive index, the ultrathin organic layer significantly reduces the lateral optical path of light emanating from the critical angle as described in this disclosure, thereby allowing for a narrower bottom surface of the second sub-pixel and consequently higher resolution.

[0264] In another embodiment, this disclosure also provides a display device incorporating the display panel of this disclosure, which can have good anti-color bleeding performance.

[0265] The following examples further illustrate this disclosure, but the disclosure is not limited to these examples.

[0266] Example 1:

[0267] The device fabricated in this series of embodiments is a blue OLED superimposed QD wavelength conversion unit structure, an On EL route, in which the TFT, light-emitting unit and QD wavelength conversion unit are fabricated on a single substrate. In this embodiment, the encapsulation layer of the light-emitting unit is a three-layer encapsulation structure, approximately 10 μm.

[0268] The backplane has the following stacked structure in sequence: TFT layer, PNL layer, anode ITO / Ag / ITO layer, first pixel limiting layer, blue light emitting layer, cathode layer, thin film encapsulation layer, low temperature second pixel limiting layer, sidewall reflective metal layer of second pixel limiting layer, QD wavelength conversion unit layer, low temperature color filter layer, low temperature OC layer, and white glass cover plate.

[0269] The substrate is cleaned using standard methods and then prepared using the TFT process.

[0270] An ITO / Ag / ITO layer with a thickness of 80 / 1000 / 120 Å was deposited by sputtering, and a photoresist was coated by spin coating. The ITO / Ag / ITO layer was patterned by pre-baking, exposure, development and wet etching.

[0271] A first pixel defining layer material is coated by spin coating; the first pixel defining layer is prepared by adjusting the process conditions such as pre-baking, exposure, development, post-baking, and ashing, with a thickness of 0.5 to 2.0 μm and a top width of 50 μm;

[0272] Blue OLED emitting layer prepared by vapor deposition;

[0273] MgAg cathode layers of 80 to 120 Å were prepared using sputtering equipment;

[0274] Thin-film encapsulation layers of 1 μm SiN, 8 μm organic layer, and 1 μm SiON were fabricated using PECVD and inkjet printing (IJP), with refractive indices of 1.9, 1.5, and 1.8, respectively.

[0275] The low-temperature black second pixel defining layer body material is coated by spin coating; the pre-baking, exposure, development, and post-baking process conditions are adjusted, and the BM thickness is 10 to 13 μm; when the second pixel defining layer body is patterned, it has the same width as the top of the first pixel defining layer, and after curing, it forms an undercut with a depth of 4 to 9 μm;

[0276] A reflective metal layer is fabricated by sputtering a Ti / Al / Ti 3000Å ​​metal layer followed by ICP dry etching. The encapsulation layer at the bottom cut is covered by the reflective metal layer, so the bottom surface of the second pixel limiting layer is the same width as the top surface of the first pixel limiting layer.

[0277] IJP method was used to print R / G QD Ink material and B pixel scattering particle Ink material; the pre-baking, exposure, development and post-baking process conditions were adjusted, and the thickness was 10 to 12 μm; the ratio of the brightness conversion rate of red and green QD layers to blue light was 2:1;

[0278] Low-temperature RGB CF material was coated using spin coating; process conditions such as pre-baking, exposure, development, and post-baking were adjusted to achieve a thickness of 2μm.

[0279] A low-temperature, low-refractive-index outer protective layer OC material (refractive index 1.4) was coated by spin coating; the pre-baking, exposure, development, and post-baking process conditions were adjusted to achieve a thickness of 2.0 μm.

[0280] It is sealed with a white glass cover.

[0281] The optical path is calculated based on x1% = p × (1 / 2) = 1.55%, excluding total internal reflection. Light with an exit angle of approximately 52° or higher, originating from the bottom of the encapsulation layer, will undergo total internal reflection at the SiON-organic layer interface and cannot enter the organic layer from the SiON. Therefore, when considering x1%, only the portion between the initial exit angle of 0-52° is taken. Testing shows that in this embodiment, the light intensity with an exit angle between 51° and 52° accounts for approximately 1.55% of the total light intensity between 0° and 52°. Based on an exit angle of 51°, it moves laterally 1.2 μm within the 1 μm thick SiON layer. Upon entering the organic layer, the exit angle is approximately 80°, and it moves laterally 45.4 μm within the 8 μm thick organic layer. After entering the SiNx layer, the exit angle becomes 55°, and it moves laterally 1.4 μm within the 1 μm thick SiNx layer. The total lateral movement distance is calculated to be 48μm, which is less than the bottom width of the second pixel limiting layer (50μm), and therefore cannot reach the wavelength conversion unit of the adjacent sub-pixel.

[0282] According to the scheme disclosed herein, color mixing prevention can be achieved in a structure without setting an additional vertical light-blocking layer.

[0283] Example 2:

[0284] The device fabricated in this series of embodiments is a blue OLED superimposed QD wavelength conversion unit structure, using an On EL approach. The TFT, light-emitting unit, and QD wavelength conversion unit are fabricated on a single substrate. In this embodiment, the encapsulation layer of the light-emitting unit is a three-layer encapsulation structure, approximately 2 μm thick. This structure uses molecular layer deposition and atomic layer deposition equipment to make the film layer more compact. While ensuring reliability, the EL encapsulation layer is thinned and optimized. Based on the previous size design calculations, compared with Embodiment 1, this embodiment can increase the design aperture ratio by more than 60%.

[0285] The backplane has the following stacked structure in sequence: TFT layer, PNL layer, anode ITO / Ag / ITO layer, first pixel limiting layer, blue light emitting layer, cathode layer, thin film encapsulation layer, low temperature second pixel limiting layer, sidewall reflective metal layer of second pixel limiting layer, QD wavelength conversion unit layer, low temperature color filter layer, low temperature OC layer, and white glass cover plate.

[0286] The substrate is cleaned using standard methods and then prepared using the TFT process.

[0287] An ITO / Ag / ITO layer with a thickness of 80 / 1000 / 120 Å was deposited by sputtering, and a photoresist was coated by spin coating. The ITO / Ag / ITO layer was patterned by pre-baking, exposure, development and wet etching.

[0288] A first pixel defining layer material is coated by spin coating; the first pixel defining layer is prepared by adjusting the process conditions such as pre-baking, exposure, development, post-baking, and ashing, with a thickness of 0.5 to 2.0 μm and a top width of 8 μm;

[0289] Blue OLED emitting layer prepared by vapor deposition;

[0290] MgAg cathode layers of 80 to 120 Å were prepared using sputtering equipment;

[0291] Thin film encapsulation layers of 0.4 to 0.7 μm SiN, 0.3 to 0.6 μm organic layer, and 1 μm Al2O3 were fabricated using PECVD, molecular layer deposition (MLD), and atomic layer deposition (ALD).

[0292] The low-temperature black second pixel defining layer body material is coated by spin coating; the pre-baking, exposure, development, and post-baking process conditions are adjusted, and the BM thickness is 10 to 13 μm; when the second pixel defining layer body is patterned, it has the same width as the top of the first pixel defining layer, and after curing, it forms an undercut with a depth of 4 to 9 μm;

[0293] A reflective metal layer is fabricated by sputtering a Ti / Al / Ti 3000Å ​​metal layer followed by ICP dry etching. The encapsulation layer at the bottom cut is covered by the reflective metal layer, so the bottom surface of the second pixel limiting layer is the same width as the top surface of the first pixel limiting layer.

[0294] IJP method was used to print R / G QD Ink material and B pixel scattering particle Ink material; the pre-baking, exposure, development and post-baking process conditions were adjusted, and the thickness was 10 to 12 μm; the ratio of the brightness conversion rate of red and green QD layers to blue light was 2:1;

[0295] Low-temperature RGB CF material was coated using spin coating; process conditions such as pre-baking, exposure, development, and post-baking were adjusted to achieve a thickness of 2μm.

[0296] A low-temperature, low-refractive-index outer protective layer OC material (refractive index 1.4) was coated by spin coating; the pre-baking, exposure, development, and post-baking process conditions were adjusted to achieve a thickness of 2.0 μm.

[0297] It is sealed with a white glass cover.

[0298] Similar to Example 1, it was verified that the total lateral movement distance of light emitted from the bottom surface of the transparent spacer layer at the critical angle corresponding to a light emission ratio of 1.55% is less than 4μm, which is less than the bottom surface width of the second pixel limiting layer (8μm), and cannot reach the wavelength conversion unit of the adjacent sub-pixel.

[0299] By employing molecular layer deposition to reduce the thickness of the low-refractive-index organic layer in the transparent spacer layer, anti-color bleeding effect can be achieved with good resolution.

[0300] Example 3:

[0301] The devices fabricated in this series of embodiments are blue OLEDs with superimposed QD wavelength conversion units, following an On-EL approach. The TFT, light-emitting unit, and QD wavelength conversion unit are fabricated on a single substrate. In this embodiment, the light-emitting unit has a three-layer encapsulation structure, approximately 10 μm thick. The second pixel defining layer has a trapezoidal cross-section, which is more conducive to light emission.

[0302] The backplane has the following stacked structure in sequence: TFT layer, PNL layer, anode ITO / Ag / ITO layer, first pixel limiting layer, blue light emitting layer, cathode layer, thin film encapsulation layer, low temperature second pixel limiting layer, sidewall reflective metal layer of second pixel limiting layer, QD wavelength conversion unit layer, low temperature color filter layer, low temperature OC layer, and white glass cover plate.

[0303] The substrate is cleaned using standard methods and then prepared using the TFT process.

[0304] An ITO / Ag / ITO layer with a thickness of 80 / 1000 / 120 Å was deposited by sputtering, and a photoresist was coated by spin coating. The ITO / Ag / ITO layer was patterned by pre-baking, exposure, development and wet etching.

[0305] A first pixel defining layer material is coated by spin coating; the first pixel defining layer is prepared by adjusting the process conditions such as pre-baking, exposure, development, post-baking, and ashing, with a thickness of 0.5 to 2.0 μm and a top width of 8 μm;

[0306] Blue OLED emitting layer prepared by vapor deposition;

[0307] MgAg cathode layers of 80 to 120 Å were prepared using sputtering equipment;

[0308] Thin film encapsulation layers of 1 μm SiON, 8 μm organic layer, and 1 μm SiNx were fabricated using PECVD and IJP.

[0309] The low-temperature black second pixel defining layer body material is coated by spin coating; the pre-baking, exposure, development, and post-baking process conditions are adjusted, and the BM thickness is 10 to 13 μm; the bottom of the second pixel defining layer has the same width as the top of the first pixel defining layer, and its top width is 6 micrometers, forming a positive trapezoidal cross section;

[0310] Since there is no bottom cut, a Ti / Al / Ti 3000Å ​​metal is deposited by sputtering, and then a layer of photoresist is coated by slot coating. After exposure and development, the photoresist pattern protects the sidewall metal from being etched. The protection range is the entire trapezoidal sidewall. Then, ICP dry etching is used to etch away the metal at the top and inside the pixel to create a reflective metal layer on the sidewall.

[0311] IJP method is used to print R / G QD Ink material and B pixel scattering particle Ink material; adjust the pre-baking, exposure, development and post-baking process conditions, the thickness is 10 to 12 μm; the ratio of the brightness conversion rate of red and green QD layers to blue light is 2:1;

[0312] Low-temperature RGB color film material was coated using spin coating; process conditions such as pre-baking, exposure, development, and post-baking were adjusted to achieve a thickness of 2μm.

[0313] A low-temperature, low-refractive-index outer protective layer OC material (refractive index 1.4) was coated by spin coating; the pre-baking, exposure, development, and post-baking process conditions were adjusted to achieve a thickness of 2.0 μm.

[0314] It is sealed with a white glass cover.

[0315] Similar to Example 1, it was verified that light emitted from the bottom surface of the transparent spacer layer at the critical angle corresponding to a light emission ratio of 1.55% could not reach the wavelength conversion unit of the adjacent sub-pixel.

[0316] A wavelength conversion unit with a top width greater than a bottom width is more conducive to light output.

[0317] As can be seen, this disclosure provides a display panel having a light-emitting layer, a transparent spacer layer on the light-emitting layer, and a wavelength conversion layer on the transparent spacer layer, wherein, based on the brightness change rate of the wavelength conversion units of adjacent pixels and the optical path characteristics of the transparent spacer layer, the color crosstalk problem of the wavelength conversion type display panel is at least partially solved by controlling the proportion of light intensity reaching the wavelength conversion units of adjacent sub-pixels within a certain limit.

[0318] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A display panel, comprising: The light-emitting layer on the substrate The transparent spacer layer on the light-emitting layer, and Wavelength conversion layer on the transparent spacer layer, The display panel includes an array of sub-pixels, each sub-pixel comprising adjacent first and second sub-pixels. Each of the first and second sub-pixels includes a light-emitting unit in the light-emitting layer and a wavelength conversion unit in the wavelength conversion layer. The light-emitting unit and the wavelength conversion unit are stacked and separated by the transparent spacer layer. The light-emitting units of the first sub-pixel and the second sub-pixel are separated by the first pixel defining layer in the light-emitting layer, and the top surface spacing is d2. The wavelength conversion unit of the first sub-pixel is a first wavelength conversion unit and the brightness change rate of the light emitted by the light-emitting unit is ra; the wavelength conversion unit of the second sub-pixel is a second wavelength conversion unit and the brightness change rate of the light emitted by the light-emitting unit is rb; the wavelength conversion units of the first sub-pixel and the second sub-pixel are separated by a second pixel defining layer in the wavelength conversion layer; wherein, the brightness change rate of the wavelength conversion unit for the light emitted by the light-emitting unit represents the ratio of the brightness of the wavelength-converted light emitted from the wavelength conversion unit to the brightness of the light incident on the wavelength conversion unit; In the direction from the first sub-pixel to the second sub-pixel, the displacement of the orthographic projection on the substrate relative to the top surface of the light-emitting unit of the second sub-pixel and the boundary of the first pixel defining layer between the light-emitting units of the first and second sub-pixels, and the displacement of the bottom surface of the second wavelength conversion unit and the boundary of the second pixel defining layer between the wavelength conversion units of the first and second sub-pixels, relative to the boundary of the first pixel defining layer between the light-emitting units of the second and second sub-pixels, is d42. Among the light incident from the top surface of the light-emitting unit of the first sub-pixel onto the transparent spacer layer and reaching the top surface of the transparent spacer layer, the intensity of light with an exit angle of α1 or greater accounts for x1%, where x1% = p1 × (ra / rb), and p1 ≤ 5%. Wherein, when the emission angle of light originating from the bottom surface of the transparent spacer is α1, the length of the projection of the light path through the transparent spacer onto the substrate is less than or equal to d2+d42. The thickness of the transparent spacer layer is d1, and the transparent spacer layer comprises m sub-layers stacked from bottom to top, wherein the thickness and refractive index of the i-th sub-layer are L and L, respectively. i and n i i is from 1 to m. All parameters satisfy: Where i is an integer from 1 to m, n i sinθ 1i is a constant and θ 11 =α1.

2. The display panel according to claim 1, wherein, p1≤2%。 3. The display panel according to claim 1, wherein, When the emission angle of light originating from the bottom surface of the transparent spacer layer is α1, the length of the projection of the light path through the transparent spacer layer onto the substrate is less than d2+d42, and the difference between d2+d42 and the length of the projection is less than or equal to 5μm.

4. The display panel according to claim 1, wherein, In the direction from the second sub-pixel to the first sub-pixel, the displacement of the orthographic projection on the substrate relative to the top surface of the first sub-pixel's light-emitting unit and the boundary of the first pixel defining layer between the first and second sub-pixels' light-emitting units, and the displacement of the bottom surface of the first wavelength conversion unit and the boundary of the second pixel defining layer between the first and second sub-pixels' wavelength conversion units', relative to the boundary of the first sub-pixel's light-emitting unit and the boundary of the second pixel defining layer's boundary, relative to the boundary of the first and second sub-pixels' light-emitting units, is d41. Specifically, among the light incident from the top surface of the light-emitting unit of the second sub-pixel onto the transparent spacer layer and reaching the top surface of the transparent spacer layer, the intensity proportion of light with an exit angle of α2 or greater is x2%, where x2% = p2 × (rb / ra), and p2 ≤ 5%. Wherein, when the emission angle of light originating from the bottom surface of the transparent spacer layer is α2, the length of the projection of the light path through the transparent spacer layer onto the substrate is less than or equal to d2+d41.

5. The display panel according to claim 4, wherein, p2=p1.

6. The display panel according to claim 4, wherein, d41=d42.

7. The display panel according to claim 4, wherein, |d41|≤5μm, |d42|≤5μm.

8. The display panel according to claim 1, wherein, The array of sub-pixels further includes a third sub-pixel, adjacent to the first sub-pixel. The third sub-pixel includes a light-emitting unit in the light-emitting layer and a transparent color-resisting unit in the wavelength conversion layer. The light-emitting unit and the transparent color-resisting unit are stacked and separated by the transparent spacer layer. The light-emitting units of the first sub-pixel and the third sub-pixel are separated by the first pixel defining layer in the light-emitting layer, and the top surface spacing is d5. The transparent color resist unit does not perform wavelength conversion on the light emitted by the light-emitting unit and the brightness change rate is rc. The wavelength conversion unit of the first sub-pixel and the transparent color resist unit of the third sub-pixel are separated by the second pixel limiting layer in the wavelength conversion layer. The brightness change rate of the transparent color resist unit on the light emitted by the light-emitting unit represents the ratio of the brightness of the light emitted from the transparent color resist unit to the brightness of the light incident on the transparent color resist unit. In the direction from the third sub-pixel to the first sub-pixel, the displacement of the orthographic projection on the substrate relative to the top surface of the light-emitting unit of the first sub-pixel and the boundary of the first pixel defining layer between the light-emitting units of the first and third sub-pixels, and the displacement of the bottom surface of the first wavelength conversion unit and the boundary of the second pixel defining layer between the wavelength conversion unit of the first sub-pixel and the transparent color resist unit of the third sub-pixel, is d43. Among the light incident from the top surface of the light-emitting unit of the third sub-pixel onto the transparent spacer layer and reaching the top surface of the transparent spacer layer, the intensity of light with an exit angle of α3 or greater accounts for x3%, where x3% = p3 × (rc / ra), and p3 ≤ 5%. Wherein, when the emission angle of light originating from the bottom surface of the transparent spacer layer is α3, the length of the projection of the light path through the transparent spacer layer onto the substrate is less than or equal to d5+d43.

9. The display panel according to claim 8, wherein, The light-emitting unit emits blue light, the third sub-pixel is a blue sub-pixel, the first sub-pixel is a red sub-pixel, and the second sub-pixel is a green sub-pixel.

10. The display panel according to claim 9, wherein, ra is at [110%, 180%], rb is at [25%, 70%], and rc is at [60%, 85%].

11. The display panel according to claim 1, wherein, The wavelength conversion unit contains quantum dots.

12. The display panel according to claim 1, wherein, The transparent spacer layer comprises a first inorganic layer, an organic layer, and a second inorganic layer stacked from bottom to top.

13. The display panel according to claim 12, wherein, The first inorganic layer is a SiNx layer, the second inorganic layer is a SiONx layer or an Al2O3 layer, and the organic layer is an epoxy resin layer or a polyacrylic resin layer.

14. The display panel according to claim 12, wherein, The thickness of the organic layer is in the range of 4 to 8 μm.

15. The display panel according to claim 12, wherein, The thickness of the organic layer is in the range of 0.3 to 0.6 μm.

16. The display panel according to claim 1, wherein, The top surface width of the second pixel-defined layer is smaller than its bottom surface width.

17. The display panel according to claim 1, wherein, The second pixel defining layer includes a main body portion and a cladding layer on the sidewall of the main body portion.

18. The display panel according to claim 17, wherein, The coating is an ink penetration protection layer.

19. The display panel according to claim 17, wherein, The coating includes reflective or light-absorbing materials.

20. The display panel according to claim 17, wherein, The coating material is metal.

21. The display panel according to claim 17, wherein, The overlay has a laterally extending portion at the bottom that covers the surface of the transparent spacer layer and extends away from the main body.

22. The display panel according to claim 21, wherein, The main body has an undercut, and the laterally extended portion of the covering layer covers the undercut.

23. The display panel according to claim 22, wherein, The depth of the undercut is in the range of 4 to 9 micrometers.

24. The display panel according to claim 1, further comprising a color filter layer on the wavelength conversion layer.

25. A method for manufacturing the display panel of claim 1, wherein, The second pixel definition layer is obtained through the following steps: Obtain the main body with an undercut; A coating layer is sputtered and deposited on the surfaces of the transparent spacer layer and the main body. The coating on the top surface of the main body and the portion of the coating on the transparent spacer layer not covered by the top surface of the main body are removed by dry etching, while the coating on the sidewalls of the main body and the undercut are retained.

26. The method of claim 25, wherein, The undercut body is obtained by curing a black material at low temperature.

27. The method according to claim 25, wherein, The transparent spacer layer includes an organic layer, which is prepared by molecular layer deposition.

28. A display device comprising a display panel according to any one of claims 1 to 24 or a display panel prepared by the method according to any one of claims 25 to 27.

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