Display substrate and manufacturing method thereof, and display device

Abstract

A display substrate, a method for manufacturing the same, and a display device. The display substrate includes a color filter layer, a color conversion layer, and a WOLED functional layer stacked sequentially on the substrate. The WOLED functional layer is configured to emit white light, which is emitted from the substrate after passing through the color conversion layer and the color filter layer. The color filter layer includes multiple red, green, blue, and white color filter regions spaced apart. The color conversion layer includes a first color conversion region, corresponding to the white color filter region, and configured to convert the green portion of the white light from the WOLED functional layer into red light.

Description

Technical Field

[0001] This article relates to but is not limited to display technology, in particular to a display substrate and its preparation method, and a display device. Background Art

[0002] White organic light-emitting diode (WOLED) display substrates are widely used in large and ultra-large TV displays and ultra-high-resolution augmented reality (AR) / virtual reality (VR) displays because they are not restricted by fine metal masks (FMMs) during fabrication. However, some WOLED display technologies suffer from high power consumption. Summary of the Invention

[0003] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0004] The embodiments of the present disclosure provide a display substrate and a method for manufacturing the same, and a display device, which solve the problem of high display power consumption of a WOLED display device.

[0005] In a first aspect, embodiments of the present disclosure provide a display substrate, comprising a color filter layer, a color conversion layer, and a WOLED functional layer sequentially stacked on the substrate. The WOLED functional layer is configured to emit white light, which is emitted from the substrate after passing through the color conversion layer and the color filter layer. The color filter layer includes a plurality of red, green, blue, and white color filter regions spaced apart. The color conversion layer includes a first color conversion region, corresponding to the white color filter region, and configured to convert a green portion of the white light from the WOLED functional layer into red light.

[0006] In some exemplary embodiments, the color conversion layer further includes at least one of a second color conversion region and a third color conversion region; wherein the second color conversion region corresponds to the red color filter region and is configured to convert a blue light portion of the white light from the WOLED functional layer into red light; and the third color conversion region corresponds to the green color filter region and is configured to convert a blue light portion of the white light from the WOLED functional layer into green light.

[0007] In some exemplary embodiments, the WOLED functional layer includes a first blue organic light-emitting layer, a green organic light-emitting layer, a red organic light-emitting layer, and a second blue organic light-emitting layer stacked in sequence in a direction perpendicular to the substrate; the material of the green organic light-emitting layer includes a dual host material, and the HOMO energy level of at least one of the dual host materials is greater than or equal to 5.5 electron volts.

[0008] In some exemplary embodiments, the maximum emission wavelength of the material of the first color conversion region is greater than or equal to 580 nanometers and less than or equal to 660 nanometers; the absorption spectrum of the material of the first color conversion region overlaps with the green emission spectrum of the WOLED functional layer, and the area of ​​the overlapping portion is greater than 30% of the area of ​​the green emission spectrum.

[0009] In some exemplary embodiments, the absorption spectrum of the material of the first color conversion region does not overlap with the blue emission spectrum of the WOLED functional layer.

[0010] In some exemplary embodiments, the maximum emission wavelength of the material of the second color conversion zone is greater than or equal to 580 nanometers and less than or equal to 660 nanometers; the absorption spectrum of the material of the second color conversion zone overlaps with the blue emission spectrum and the green emission spectrum in the emission spectrum of the WOLED functional layer, and the total overlapping area with the blue emission spectrum and the green emission spectrum is greater than 90% of the sum of the areas of the blue emission spectrum and the green emission spectrum.

[0011] In some exemplary embodiments, the maximum emission wavelength of the material of the third color conversion zone is greater than or equal to 480 nanometers and less than or equal to 580 nanometers; the absorption spectrum of the material of the third color conversion zone overlaps with the blue emission spectrum in the emission spectrum of the WOLED functional layer, and the area of ​​the overlapping portion is greater than 90% of the area of ​​the blue emission spectrum.

[0012] In some exemplary embodiments, the substrate includes a base and a driving structure layer disposed on the base, the driving structure layer includes a pixel driving circuit, and the driving structure layer is configured to drive the WOLED functional layer to emit light.

[0013] In some exemplary embodiments, the display substrate further includes an encapsulation layer, and the encapsulation layer is located on a side of the WOLED functional layer away from the substrate.

[0014] In a second aspect, an embodiment of the present disclosure further provides a display device, comprising the display substrate in any of the above embodiments.

[0015] In a third aspect, an embodiment of the present disclosure further provides a method for preparing a display substrate, the method comprising: forming a color filter layer on a substrate, the color filter layer comprising a plurality of red, green, blue, and white color filter regions spaced apart; forming a color conversion layer on the substrate, the color conversion layer comprising a first color conversion region, the first color conversion region corresponding to the white color filter region and configured to convert a green portion of white light from a WOLED functional layer into red light; and forming a WOLED functional layer on the substrate, the WOLED functional layer configured to emit white light, the white light being emitted from the substrate after passing through the color conversion layer and the color filter layer.

[0016] In some exemplary embodiments, the color conversion layer further includes at least one of a second color conversion region and a third color conversion region; and forming the color conversion layer on the substrate includes: forming a first color conversion region, a second color conversion region, and / or a third color conversion region on the substrate, respectively; wherein the second color conversion region corresponds to the red color filter region and is configured to convert a blue portion of the white light from the WOLED functional layer into red light; and the third color conversion region corresponds to the green color filter region and is configured to convert a blue portion of the white light from the WOLED functional layer into green light.

[0017] In some exemplary embodiments, forming a WOLED functional layer on the substrate includes: sequentially forming a first blue organic light-emitting layer, a green organic light-emitting layer, a red organic light-emitting layer, and a second blue organic light-emitting layer on the substrate; wherein the material of the green organic light-emitting layer includes a dual host material, and the HOMO energy level of at least one of the dual host materials is greater than or equal to 5.5 electron volts.

[0018] In some exemplary embodiments, after forming the WOLED functional layer on the substrate, the method further includes forming an encapsulation layer on a side of the WOLED functional layer away from the substrate.

[0019] In the display substrate provided by the disclosed embodiments, each color filter area corresponds to a sub-pixel, and images are displayed on the screen by lighting different sub-pixels. A color conversion layer is provided between the WOLED functional layer and the color filter layer, with a first color conversion area corresponding to the white color filter area. This first color conversion area converts the green portion of white light from the WOLED functional layer into red light, thereby increasing the red portion and reducing the green portion of the white light passing through the first color conversion area. This changes the type of sub-pixels that require fill light during screen display, reducing the screen's display power consumption.

[0020] In the display substrate manufacturing method provided by the embodiments of the present disclosure, a color conversion layer is formed between the WOLED functional layer and the color filter layer, and a first color conversion region is formed corresponding to the white color filter region. The first color conversion region can convert the green light portion of the white light from the WOLED functional layer into red light, thereby increasing the red light portion and reducing the green light portion of the white light passing through the first color conversion region. This changes the type of sub-pixels requiring fill light during screen display, and can reduce the screen's display power consumption.

[0021] Other features and advantages of the present disclosure will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present disclosure. Other advantages of the present disclosure can be realized and obtained through the solutions described in the description and the drawings.

[0022] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide an understanding of the technical solution of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solution of the present disclosure and do not constitute a limitation to the technical solution of the present disclosure.

[0024] Figure 1 A schematic cross-sectional view of a display substrate provided in an embodiment of the present disclosure;

[0025] Figure 2 The WOLED functional layer and the emission spectrum of the WOLED functional layer after passing through the first color conversion region;

[0026] Figure 3 FIG. 1 is a schematic diagram showing a cross-sectional structure of a substrate in another exemplary embodiment. DETAILED DESCRIPTION

[0027] The present disclosure describes a plurality of embodiments, but this description is exemplary rather than restrictive, and it will be apparent to those skilled in the art that there may be more embodiments and implementations within the scope of the embodiments described in the present disclosure. Although many possible feature combinations are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.

[0028] The present disclosure includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The disclosed embodiments, features, and elements of the present disclosure may also be combined with any conventional features or elements to form a unique inventive solution defined by the claims. Any features or elements of any embodiment may also be combined with features or elements from other inventive solutions to form another unique inventive solution defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in this disclosure may be implemented individually or in any appropriate combination. Therefore, the embodiments are not subject to other limitations except for the limitations set forth in the appended claims and their equivalents. In addition, various modifications and changes may be made within the scope of protection of the appended claims.

[0029] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps in the specific order described. As will be understood by those skilled in the art, other orders of steps are also possible. Therefore, the specific order of the steps set forth in the specification should not be interpreted as a limitation on the claims. In addition, the claims to the method and / or process should not be limited to performing their steps in the order written, and those skilled in the art can readily understand that these orders can be changed and still remain within the spirit and scope of the disclosed embodiments.

[0030] In the drawings, the size of one or more components, layer thicknesses, or regions may be exaggerated for clarity. Therefore, one embodiment of the present disclosure is not necessarily limited to these dimensions, and the shapes and sizes of one or more components in the drawings do not reflect true proportions. Furthermore, the drawings schematically illustrate idealized examples, and one embodiment of the present disclosure is not limited to the shapes or values ​​shown in the drawings.

[0031] The scales of the figures in this disclosure can be used as a reference for actual processes, but are not limited to such. For example, the width-to-length ratio of the channel, the thickness and spacing of the various film layers, and the width and spacing of the various signal lines can be adjusted according to actual needs. The number of pixels in the display substrate and the number of sub-pixels in each pixel are not limited to the numbers shown in the figures. The figures described in this disclosure are merely schematic structural diagrams, and one embodiment of this disclosure is not limited to the shapes or values ​​shown in the figures.

[0032] In this specification, ordinal numbers such as "first," "second," and "third" are provided to avoid confusion among constituent elements, and are not intended to limit the number. "Multiple" in this disclosure means two or more.

[0033] In this specification, for convenience, words and phrases indicating orientation or positional relationships, such as "middle," "upper," "lower," "front," "back," "vertical," "horizontal," "top," "bottom," "inside," and "outside," are used to illustrate the positional relationships of constituent elements with reference to the accompanying drawings. This is merely for the purpose of facilitating the description of this specification and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present disclosure. The positional relationships of constituent elements may be appropriately changed depending on the orientation of the constituent elements being described. Therefore, the present disclosure is not limited to the words and phrases described in the specification and may be appropriately replaced depending on the circumstances.

[0034] In this specification, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, or a detachable connection, or an integral connection; it can be a mechanical connection, or a connection; it can be a direct connection, or an indirect connection through an intermediate piece, or a connection between the two elements. For those of ordinary skill in the art, the meaning of the above terms in this disclosure can be understood according to the circumstances. Among them, "electrical connection" includes the situation where constituent elements are connected together through an element with some electrical function. There is no special restriction on "elements with some electrical function" as long as they can transmit electrical signals between connected constituent elements. Examples of "elements with some electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other elements with one or more functions.

[0035] In this specification, a transistor refers to a device that includes at least three terminals: a gate electrode, a drain electrode, and a source electrode. A transistor has a channel region between a drain electrode (drain electrode terminal, drain region, or drain) and a source electrode (source electrode terminal, source region, or source), and current can flow through the drain electrode, the channel region, and the source electrode. Note that in this specification, the channel region refers to the region through which current primarily flows.

[0036] In this specification, the first electrode can be a drain electrode and the second electrode can be a source electrode, or vice versa. The functions of "source electrode" and "drain electrode" may be interchanged when using transistors with opposite polarity or when the direction of current changes during circuit operation. Therefore, in this specification, "source electrode" and "drain electrode" may be interchanged.

[0037] In this specification, the terms "film" and "layer" may be interchanged. For example, "conductive layer" may be replaced with "conductive film." Similarly, "insulating film" may be replaced with "insulating layer."

[0038] The triangles, rectangles, trapezoids, pentagons or hexagons in this specification are not in the strict sense, but may be approximate triangles, rectangles, trapezoids, pentagons or hexagons, etc. There may be some small deformations caused by tolerances, and there may be chamfers, arc edges and deformations.

[0039] The term "about" in the present disclosure refers to a numerical value that is not strictly defined and allows for process and measurement errors.

[0040] Among some technologies, WOLED display technology uses a white-light-emitting OLED device (i.e., WOLED) combined with a color filter (CF) to achieve full-color display. Commonly used color filters (color filters) are absorptive, and light can complete color conversion when passing through the color filter. The color filter includes multiple red, green, blue, and white color filter areas. After passing through the color filter, light is displayed as corresponding red, green, blue, and white, and the corresponding image display is formed by different color combinations. However, when displaying a certain image, a WOLED display device requires different colors of light to work together. Even when displaying a pure color image, it still requires light other than that color to provide fill light, which makes the WOLED display device have high display power consumption.

[0041] An embodiment of the present disclosure provides a display substrate, comprising a color filter layer, a color conversion layer, and a WOLED functional layer stacked sequentially on the substrate. The WOLED functional layer is configured to emit white light, which is emitted from the substrate after passing through the color conversion layer and the color filter layer. The color filter layer includes a plurality of red, green, blue, and white color filter regions spaced apart. The color conversion layer includes a first color conversion region, which corresponds to the white color filter region and is configured to convert the green portion of the white light from the WOLED functional layer into red light.

[0042] In the display substrate provided by the embodiments of the present disclosure, each color filter area corresponds to a sub-pixel, and images are displayed on the screen by illuminating different sub-pixels. A color conversion layer is provided between the WOLED functional layer and the color filter layer, and a first color conversion area is provided corresponding to the white color filter area. The first color conversion area converts the green portion of white light from the WOLED functional layer into red light, thereby increasing the red portion and reducing the green portion of the white light passing through the first color conversion area. This changes the type of sub-pixels requiring fill light during screen display, thereby reducing the screen's display power consumption. Using the display substrate of the embodiments of the present disclosure can reduce the screen's display power consumption. In some technologies, because WOLED display technology uses WOLED devices combined with color filters to achieve full-color display, when light passes through the red, green, and blue color filter areas, the incident light is white, and the outgoing light is the color of the corresponding sub-pixel. Light of other colors cannot pass through the filters, resulting in significant brightness loss, low energy utilization efficiency, and increased display power consumption.

[0043] In some exemplary embodiments, the color conversion layer further includes at least one of a second color conversion region and a third color conversion region; wherein the second color conversion region corresponds to the red color filter region and is configured to convert a blue light portion of the white light from the WOLED functional layer into red light; and the third color conversion region corresponds to the green color filter region and is configured to convert a blue light portion of the white light from the WOLED functional layer into green light.

[0044] In this embodiment, by providing a second color conversion region corresponding to the red color filter region, the second color conversion region converts the blue portion of white light from the WOLED functional layer into red light, increasing the intensity of the incident light that can pass through the red color filter region, thereby improving the luminance of the red sub-pixel and reducing the power consumption of the red sub-pixel. Similarly, by providing a third color conversion region corresponding to the green color filter region, the third color conversion region converts the blue portion of white light from the WOLED functional layer into green light, increasing the intensity of the light that can pass through the green color filter region, thereby improving the luminance of the green sub-pixel and reducing the power consumption of the red sub-pixel. By reducing the power consumption of individual sub-pixels, the overall power consumption of the display substrate can be reduced.

[0045] In some exemplary embodiments, a color conversion region corresponds to a color filter region, and the orthographic projections of the color conversion region and the corresponding color filter region on the substrate may overlap. For example, if the first color conversion region corresponds to the white color filter region, the orthographic projections of the first color conversion region and the white color filter region on the substrate may overlap.

[0046] In some exemplary embodiments, a color conversion region corresponds to a color filter region, and the orthographic projection of the color conversion region and the corresponding color filter region on the substrate may overlap. For example, if the first color conversion region corresponds to the white color filter region, the orthographic projection of the first color conversion region and the white color filter region on the substrate may overlap.

[0047] In some technologies, the WOLED device structure typically features a triple-stack structure: two blue light-emitting layers sandwich a red light-emitting layer and a green light-emitting layer, with the red and green light-emitting layers forming a single light-emitting unit (i.e., B+RG+B). This means the red and green light-emitting layers form one of the phosphorescent light-emitting units of the WOLED device. Typically, within this phosphorescent light-emitting unit, the combined luminous efficiency of the red and green light-emitting layers is constant. Improving the green light-emitting efficiency (which reduces the power consumption of the green light-emitting layer G) inevitably results in a decrease in the red light-emitting efficiency (which increases the power consumption of the red light-emitting layer R), creating a trade-off in the luminous efficiency of the red and green light-emitting layers.

[0048] In some exemplary embodiments, the WOLED functional layer includes a first blue organic light-emitting layer, a green organic light-emitting layer, a red organic light-emitting layer, and a second blue organic light-emitting layer stacked in sequence in a direction perpendicular to the substrate; the material of the green organic light-emitting layer includes a dual host material, and the HOMO energy level of at least one of the dual host materials is greater than or equal to 5.5 electron volts.

[0049] In this embodiment, the organic light-emitting layer of each color may include an emissive layer (EML) and any one or more of the following: a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer (EBL), a hole blocking layer (HBL), an electron transport layer (ETL), and an electron injection layer (EIL). This disclosure does not limit the structure of the organic light-emitting layer in the WOLED functional layer.

[0050] In this embodiment, by using dual host materials to prepare the green light-emitting layer in the WOLED functional layer, with at least one of the host materials having a HOMO energy level greater than or equal to 5.5 electron volts, the phosphorescent light-emitting unit composed of the red and green light-emitting layers initially emits a stronger green light, increasing the proportion of green light and reducing the proportion of red light. By adjusting the material composition of the green light-emitting layer in the WOLED functional layer, the first color conversion region can more easily convert green light to red light, further reducing the overall power consumption of the screen display.

[0051] In some exemplary embodiments, the maximum emission wavelength of the material of the first color conversion region is greater than or equal to 580 nanometers and less than or equal to 660 nanometers; the absorption spectrum of the material of the first color conversion region overlaps with the green emission spectrum of the WOLED functional layer, and the area of ​​the overlapping portion is greater than 30% of the area of ​​the green emission spectrum.

[0052] In an exemplary embodiment, the maximum light emission wavelength of the material of the first color conversion region may be set to be greater than or equal to 600 nanometers and less than or equal to 640 nanometers.

[0053] In some exemplary embodiments, the absorption spectrum of the material of the first color conversion region does not overlap with the blue emission spectrum of the WOLED functional layer.

[0054] In this embodiment, the absorption spectrum of the material of the first color conversion region does not overlap with the blue emission spectrum in the emission spectrum of the WOLED functional layer. That is, the first color conversion region does not absorb blue light, which can ensure the luminous efficiency of blue light and thus reduce the power consumption of the white sub-pixel.

[0055] In some exemplary embodiments, the maximum emission wavelength of the material of the second color conversion zone is greater than or equal to 580 nanometers and less than or equal to 660 nanometers; the absorption spectrum of the material of the second color conversion zone overlaps with the blue emission spectrum and the green emission spectrum in the emission spectrum of the WOLED functional layer, and the total overlapping area with the blue emission spectrum and the green emission spectrum is greater than 90% of the sum of the areas of the blue emission spectrum and the green emission spectrum.

[0056] In an exemplary embodiment, the maximum emission wavelength of the material of the second color conversion region can be set to be greater than or equal to 600 nanometers and less than or equal to 640 nanometers. The material of the second color conversion region can be, for example, a red quantum dot material, which is not limited in this disclosure.

[0057] In some exemplary embodiments, the maximum emission wavelength of the material of the third color conversion zone is greater than or equal to 480 nanometers and less than or equal to 580 nanometers; the absorption spectrum of the material of the third color conversion zone overlaps with the blue emission spectrum in the emission spectrum of the WOLED functional layer, and the area of ​​the overlapping portion is greater than 90% of the area of ​​the blue emission spectrum.

[0058] In an exemplary embodiment, the maximum light emission wavelength of the material of the third color conversion region may be set to be greater than or equal to 500 nanometers and less than or equal to 560 nanometers.

[0059] In an exemplary embodiment, the material of the third color conversion region can be a green quantum dot material. Since green quantum dot materials have a low light conversion efficiency, increasing the luminous intensity of green light in the WOLED functional layer in the initial state can enable the third color conversion region to perform better light conversion. This disclosure does not impose any restrictions on the material of the third color conversion region.

[0060] In some exemplary embodiments, the WOLED functional layer further includes an anode layer and a cathode layer. The anode layer is located on a side of the WOLED functional layer close to the substrate, and the cathode layer is located on a side of the WOLED functional layer away from the substrate.

[0061] In some exemplary embodiments, the substrate includes a base and a driving structure layer disposed on the base, the driving structure layer includes a pixel driving circuit, and the driving structure layer is configured to drive the WOLED functional layer to emit light.

[0062] In some exemplary embodiments, the display substrate further includes an encapsulation layer, and the encapsulation layer is located on a side of the WOLED functional layer away from the substrate.

[0063] In some exemplary embodiments, the encapsulation layer is located on a side of the cathode layer away from the substrate.

[0064] The display substrate provided by the embodiments of the present disclosure is described below with reference to the accompanying drawings.

[0065] Figure 1 Schematic diagram of the cross-sectional structure of the display substrate provided in the embodiment of the present disclosure. Figure 1 As shown, a color filter layer 3, a color conversion layer 4, and a WOLED functional layer 5 are provided on the substrate 1. The color filter layer 3 includes multiple color filter regions spaced apart, including a red color filter region 31, a green color filter region 32, a blue color filter region 33, and a white color filter region 34. A color conversion layer 4 is provided between the color filter layer 3 and the WOLED functional layer 5. The color conversion layer 4 includes a first color conversion region 41 corresponding to the white color filter region 34. The first color conversion region 41 can convert the green light portion of the white light from the WOLED functional layer 5 into red light. Figure 1 As shown, the orthographic projections of the first color conversion region 41 and the white color filter region 34 on substrate 1 overlap. The white light emitted by the WOLED functional layer 5 passes through the color conversion layer 4 and reaches the color filter layer 3. The white light is then emitted from the color filter layer 3 as light of different colors. These light rays of different colors then pass through substrate 1 to form an image display.

[0066] Figure 2 This is the WOLED functional layer and the emission spectrum of the WOLED functional layer after passing through the first color conversion region. Figure 2In the graph, the horizontal axis represents wavelength (Wavelength), in nanometers (nm), and the vertical axis represents the relative value of intensity. The dotted line X indicates the position of the blue luminescence peak, the dotted line Y indicates the position of the green luminescence peak, and the dotted line Z indicates the position of the red luminescence peak. Curve A represents the emission spectrum obtained by testing the WOLED functional layer 5 alone, that is, the emission spectrum of the WOLED functional layer in the initial state. Curve B represents the emission spectrum obtained after the light of the WOLED functional layer 5 passes through the first color conversion region 41. That is, the difference between curves A and B during the test is whether the light emitted by the WOLED functional layer 5 passes through the first color conversion region 41. Figure 2 As can be seen, the intensity of the blue emission peak is significantly higher than both the green and red emission peaks, while the intensity of the green emission peak is higher than the red emission peak. In this embodiment, the green emission layer in the WOLED functional layer is prepared using dual host materials, and at least one of the host materials has a HOMO energy level greater than or equal to 5.5 electron volts. Curve A shows that, in the initial state, the green emission intensity in the WOLED functional layer is significantly higher than the red emission intensity. After providing the first color conversion region, the first color conversion region can convert the green portion of white light from the WOLED functional layer into red light, increasing the red portion and decreasing the green portion of the white light passing through the first color conversion region. Therefore, compared to Curve A, Curve B shows that the intensity of the blue emission peak remains unchanged, the intensity of the green emission peak is lower than the initial intensity of the green emission peak of the WOLED functional layer, and the intensity of the red emission peak is higher than the initial intensity of the green emission peak of the WOLED functional layer.

[0067] Table 1 compares the power consumption of display substrates without and with the first color conversion region, when the screen displays pure white. The "Initial State WOLED" section in the left column of Table 1 represents a display substrate without the first color conversion region, while the "WOLED + First Color Conversion Region" section in the right column represents a display substrate with the first color conversion region. The only difference between the display substrates in the left and right columns is whether or not the first color conversion region is included.

[0068] Table 1

[0069]

[0070] As shown in Table 1, when the screen display brightness is the same at 600 nits (nits), the sub-pixels requiring fill light differ between display substrates with and without the first color conversion region. In the display substrate without the first color conversion region (i.e., the left column of Table 1), when the screen displays pure white, not only the white sub-pixel W on the screen needs to emit light, but also the red sub-pixels R and blue sub-pixels B need to emit light to provide fill light. The luminance of the white sub-pixel W is 587.4 nits, the red sub-pixel R is 9.6 nits, and the blue sub-pixel B is 3.0 nits. The combined effects of the white sub-pixels W, red sub-pixels R, and blue sub-pixels B bring the overall screen brightness to 600 nits, and the screen power consumption at this time is 387.4 W. On the display substrate with the first color conversion zone (i.e., the right column of Table 1), when the screen displays pure white, the white sub-pixel W on the screen needs to emit light, and the red sub-pixels R and green sub-pixels G also need to emit light to provide fill light. The luminance of the white sub-pixel W is 553.0 nits, the luminance of the red sub-pixel R is 1.3 nits, and the luminance of the green sub-pixel G is 45.7 nits. The combined effect of the white sub-pixels W, red sub-pixels R, and green sub-pixels G brings the overall screen brightness to 600 nits, and the screen power consumption at this time is 359.7 W.

[0071] It can be seen that after setting the first color conversion region, the sub-pixels that require fill light during screen display are different from those when the first color conversion region is not set, and the power consumption of screen display is reduced by setting the first color conversion region.

[0072] Figure 3 FIG. 1 is a schematic diagram showing a cross-sectional structure of a substrate in another exemplary embodiment. Figure 3As shown, a color filter layer 3, a color conversion layer 4, a WOLED functional layer 5 and an encapsulation layer 6 are provided on a substrate 1. The substrate 1 includes a base 10 and a driving structure layer 2 provided on the base 10. The color filter layer 3 includes a plurality of color filter areas arranged at intervals and a black matrix 35 provided between adjacent color filter areas. The plurality of color filter areas include: a red color filter area 31, a green color filter area 32, a blue color filter area 33 and a white color filter area 34. A color conversion layer 4 is disposed between the color filter layer 3 and the WOLED functional layer 5. This color conversion layer 4 includes a first color conversion region 41 corresponding to the white color filter region 34, a second color conversion region 42 corresponding to the red color filter region 31, and a third color conversion region 43 corresponding to the green color filter region 32. The orthographic projections of the corresponding color conversion regions and color filter regions on the substrate 10 overlap. The first color conversion region 41 converts the green portion of white light from the WOLED functional layer 5 into red light, the second color conversion region 42 converts the blue portion of white light from the WOLED functional layer 5 into red light, and the third color conversion region 43 converts the blue portion of white light from the WOLED functional layer 5 into green light. In a direction perpendicular to the substrate 1, the WOLED functional layer 5 includes a first blue organic light-emitting layer 51, a green organic light-emitting layer 52, a red organic light-emitting layer 53, and a second blue organic light-emitting layer 54, stacked in this order. The white light emitted by the WOLED functional layer 5 passes through the color conversion layer 4 and reaches the color filter layer 3. The color filter layer 3 then emits light of different colors. These light rays of different colors then pass through the substrate 1 to form an image display. The WOLED functional layer 5 may also include an anode layer (not shown) located on the side of the WOLED functional layer closest to the substrate 1, and a cathode layer (not shown) located on the side of the WOLED functional layer further from the substrate 1. The drive structure layer 2 may include a pixel drive circuit capable of driving the WOLED functional layer 5 to emit light. An encapsulation layer 6 may be provided on the side of the WOLED functional layer 5 (or cathode layer) further from the substrate 10.

[0073] like Figure 3As shown, in this embodiment, the maximum emission wavelength of the material of the first color conversion zone 41 is greater than or equal to 600 nanometers and less than or equal to 640 nanometers. The absorption spectrum of the material of the first color conversion zone overlaps with the green emission spectrum of the WOLED functional layer 5, and the area of ​​the overlapping portion is greater than 30% of the area of ​​the green emission spectrum. The absorption spectrum of the material of the first color conversion zone 41 does not overlap with the blue emission spectrum of the WOLED functional layer 5. The maximum emission wavelength of the material of the second color conversion zone 42 is greater than or equal to 600 nanometers and less than or equal to 640 nanometers. The absorption spectrum of the material of the second color conversion zone 42 overlaps with the blue and green emission spectra of the WOLED functional layer 5, and the total area of ​​the overlap with the blue and green emission spectra is greater than 90% of the sum of the areas of the blue and green emission spectra. The maximum emission wavelength of the material of the third color conversion zone 43 is greater than or equal to 500 nanometers and less than or equal to 560 nanometers. The absorption spectrum of the material of the third color conversion region 43 overlaps with the blue emission spectrum in the emission spectrum of the WOLED functional layer 5 , and the area of ​​the overlapping portion is greater than 90% of the area of ​​the blue emission spectrum.

[0074] The present disclosure provides a method for preparing a display substrate, comprising:

[0075] forming a color filter layer on the substrate, wherein the color filter layer comprises a plurality of red color filter areas, green color filter areas, blue color filter areas and white color filter areas that are spaced apart;

[0076] forming a color conversion layer on the substrate, the color conversion layer comprising a first color conversion region, the first color conversion region corresponding to the white color filter region, and configured to convert a green portion of the white light from the WOLED functional layer into red light;

[0077] A WOLED functional layer is formed on the substrate, and the WOLED functional layer is configured to emit white light. The white light passes through the color conversion layer and the color filter layer and then is emitted from the substrate.

[0078] In the solution of the embodiment of the present disclosure, each color filter area is equivalent to a sub-pixel, and image display is achieved on the screen by lighting different sub-pixels. By forming a color conversion layer between the WOLED functional layer and the color filter layer, and forming a first color conversion area corresponding to the white color filter area, the first color conversion area can convert the green light portion of the white light from the WOLED functional layer into red light, thereby increasing the red light portion and reducing the green light portion of the white light passing through the first color conversion area. This changes the type of sub-pixels that require fill light when the screen is displaying, and can reduce the power consumption of the screen display. The display substrate preparation method of the embodiment of the present disclosure can reduce the display power consumption of the display substrate screen.

[0079] In some exemplary embodiments, the color conversion layer further includes at least one of a second color conversion region and a third color conversion region; and forming the color conversion layer on the substrate includes: forming a first color conversion region, a second color conversion region, and / or a third color conversion region on the substrate, respectively; wherein the second color conversion region corresponds to the red color filter region and is configured to convert a blue portion of the white light from the WOLED functional layer into red light; and the third color conversion region corresponds to the green color filter region and is configured to convert a blue portion of the white light from the WOLED functional layer into green light.

[0080] In some exemplary embodiments, forming a WOLED functional layer on the substrate includes: sequentially forming a first blue organic light-emitting layer, a green organic light-emitting layer, a red organic light-emitting layer, and a second blue organic light-emitting layer on the substrate; wherein the material of the green organic light-emitting layer includes a dual host material, and the HOMO energy level of at least one of the dual host materials is greater than or equal to 5.5 electron volts.

[0081] In some exemplary embodiments, after forming the WOLED functional layer on the substrate, the method further includes forming an encapsulation layer on a side of the WOLED functional layer away from the substrate.

[0082] In some exemplary embodiments, the substrate includes a base and a driving structure layer disposed on the base, the driving structure layer includes a pixel driving circuit, and the driving structure layer is configured to drive the WOLED functional layer to emit light.

[0083] The following is Figure 3The preparation process of the display substrate shown is exemplified. The "patterning process" mentioned in the present disclosure includes processes such as coating photoresist, mask exposure, development, etching, and stripping photoresist for metal materials, inorganic materials or transparent conductive materials, and includes processes such as coating organic materials, mask exposure and development for organic materials. Deposition can be carried out by any one or more of sputtering, evaporation, and chemical vapor deposition, coating can be carried out by any one or more of spraying, spin coating and inkjet printing, and etching can be carried out by any one or more of dry etching and wet etching, and the present disclosure does not limit this. "Thin film" refers to a thin film made by deposition, coating or other processes on a substrate of a certain material. If the "thin film" does not require a patterning process during the entire production process, the "thin film" can also be called a "layer". If the "thin film" requires a patterning process during the entire production process, it is called a "thin film" before the patterning process and a "layer" after the patterning process. The "layer" after the patterning process contains at least one "pattern". As used in this disclosure, "A and B are disposed in the same layer" means that A and B are formed simultaneously through the same patterning process, and the "thickness" of the film layer refers to the dimension of the film layer in a direction perpendicular to the display substrate. In exemplary embodiments of this disclosure, "the orthographic projection of B is within the range of the orthographic projection of A" or "the orthographic projection of A contains the orthographic projection of B" means that the boundary of the orthographic projection of B falls within the boundary of the orthographic projection of A, or that the boundary of the orthographic projection of A overlaps with the boundary of the orthographic projection of B.

[0084] Figure 3 The preparation process of the display substrate may include the following steps.

[0085] (1) A driving structure layer 2 is formed on a substrate 10. In an exemplary embodiment, the driving structure layer 2 may include: a plurality of pixel driving circuits and a plurality of insulating layers disposed between the pixel driving circuits. The structure of the driving structure layer 2 may be designed as needed, and the present disclosure does not limit the structure and preparation process of the driving structure layer 2.

[0086] (2) Forming a color filter layer pattern. In an exemplary embodiment, forming a color filter layer pattern may include:

[0087] A black coating layer is formed on the patterned substrate 10 using a deposition process. The material of this black coating layer can be a highly light-shielding resin material. The black coating layer is then exposed, developed, and etched using a mask to form a black matrix 35 pattern. The black matrix 35 pattern includes openings for red, green, blue, and white color filters.

[0088] Then, a red color filter area 31 is formed at the red color filter opening, a green color filter area 32 is formed at the green color filter opening, a blue color filter area 33 is formed at the blue color filter opening, and a white color filter area 34 is formed at the white color filter opening.

[0089] (3) Forming a color conversion layer pattern. In an exemplary embodiment, forming a color conversion layer pattern may include:

[0090] On the substrate 10 formed with the aforementioned pattern, a first color conversion region 41 is formed on the white color filter region 34, a second color conversion region 42 is formed on the red color filter region 31, and a third color conversion region 43 is formed on the green color filter region 32. To form the first color conversion region 41, a first color conversion material is applied to the substrate 1, and the first color conversion material is exposed and developed using a mask to form the first color conversion region 41. To form the second color conversion region 42, a second color conversion material is applied to the substrate 1, and the second color conversion material is exposed and developed using a mask to form the second color conversion region 42. To form the third color conversion region 43, a third color conversion material is applied to the substrate 1, and the third color conversion material is exposed and developed using a mask to form the third color conversion region 43. The present disclosure does not limit the order in which the color conversion regions are formed. The first, second, and third color conversion materials can be inorganic materials containing rare earth elements, organic fluorescent materials, or quantum dot materials, and the present disclosure does not limit these materials.

[0091] Then, a planarization layer is formed on the blue color filter area 33 to make the surface of the color conversion layer flat. The planarization layer can be made of organic material.

[0092] (4) Forming a WOLED functional layer pattern. In an exemplary embodiment, forming a WOLED functional layer pattern may include:

[0093] A transparent conductive film is deposited on the patterned substrate 10 and patterned to form an anode (not shown). The anode is connected to the corresponding transistor of the pixel driving circuit in the driving structure layer 2. The transparent conductive film can be made of indium tin oxide (ITO) or indium zinc oxide (IZO).

[0094] Subsequently, on the substrate 10 on which the aforementioned pattern is formed, a multi-layer organic light-emitting layer pattern is sequentially formed by evaporation or inkjet printing. The multi-layer organic light-emitting layer includes a first blue organic light-emitting layer 51, a green organic light-emitting layer 52, a red organic light-emitting layer 53 and a second blue organic light-emitting layer 54 stacked sequentially in a direction perpendicular to the substrate 1.

[0095] Subsequently, a cathode pattern (not shown) is formed on the patterned substrate 10 by vapor deposition using an open mask. The cathode is connected to the organic light-emitting layer, achieving simultaneous connection of the organic light-emitting layer to both the anode and the first cathode. The cathode can be a reflective cathode and can be made of any one or more of magnesium (Mg), silver (Ag), aluminum (Al), copper (Cu), and lithium (Li), or an alloy of any one or more of these metals.

[0096] In exemplary embodiments, the organic light emitting layer may include an emission layer (EML), and any one or more of a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer (EBL), a hole blocking layer (HBL), an electron transport layer (ETL), and an electron injection layer (EIL).

[0097] In an exemplary embodiment, the organic light emitting layer may be prepared in the following manner:

[0098] First, an open mask (OPM) evaporation process or an inkjet printing process is used to sequentially form a hole injection layer, a hole transport layer, and an electron blocking layer, thereby forming a common layer of the hole injection layer, the hole transport layer, and the electron blocking layer on a display substrate.

[0099] Subsequently, an open-mask evaporation process or inkjet printing is used to form different light-emitting layers in different sub-pixels. The light-emitting layers of adjacent sub-pixels can have a small overlap (for example, the overlap accounts for less than 10% of the area of ​​the respective light-emitting layer patterns) or can be isolated.

[0100] Subsequently, a hole blocking layer, an electron transport layer and an electron injection layer are sequentially formed by an open mask evaporation process or an inkjet printing process, thereby forming a common layer of the hole blocking layer, the electron transport layer and the electron injection layer on the display substrate.

[0101] In exemplary embodiments, the organic light-emitting layer may include a microcavity adjustment layer, such that the thickness of the organic light-emitting layer between the cathode and the anode satisfies the design of the microcavity length. In some exemplary embodiments, a hole transport layer, an electron blocking layer, a hole blocking layer, or an electron transport layer may be used as the microcavity adjustment layer, and this disclosure is not limited thereto.

[0102] In an exemplary embodiment, the light-emitting layer may include a host material and a guest material doped in the host material, with the doping ratio of the guest material in the light-emitting layer being between 1% and 20%. Within this doping ratio range, the host material in the light-emitting layer can effectively transfer exciton energy to the guest material in the light-emitting layer to stimulate the guest material to emit light. Furthermore, the host material in the light-emitting layer "dilutes" the guest material in the light-emitting layer, effectively improving the fluorescence quenching caused by collisions between guest material molecules and energy collisions, thereby improving the luminous efficiency and device life. In an exemplary embodiment, the doping ratio refers to the ratio of the mass of the guest material to the mass of the light-emitting layer, i.e., the mass percentage. In an exemplary embodiment, the host material and the guest material can be co-evaporated using a multi-source evaporation process so that the host material and the guest material are uniformly dispersed in the light-emitting layer. The doping ratio can be controlled by controlling the evaporation rate of the guest material during the evaporation process, or by controlling the ratio of the evaporation rates of the host material and the guest material. In an exemplary embodiment, the thickness of the light-emitting layer can be approximately 10 nm to 50 nm.

[0103] In an exemplary embodiment, the hole injection layer may be made of an inorganic oxide, such as molybdenum oxide, titanium oxide, vanadium oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silver oxide, tungsten oxide, or manganese oxide, or may be made of a p-type dopant of a strong electron-withdrawing system and a dopant of a hole transport material. In an exemplary embodiment, the hole injection layer may have a thickness of approximately 5 nm to 20 nm.

[0104] In an exemplary embodiment, the hole transport layer may be made of a material with high hole mobility, such as an aromatic amine compound, whose substituent group may be carbazole, methylfluorene, spirofluorene, dibenzothiophene, or furan. In an exemplary embodiment, the hole transport layer may have a thickness of approximately 40 nm to 150 nm.

[0105] In an exemplary embodiment, the hole blocking layer and the electron transport layer may be made of aromatic heterocyclic compounds, such as imidazole derivatives such as benzimidazole derivatives, imidazopyridine derivatives, and benzimidazolephenanthridine derivatives; oxazine derivatives such as pyrimidine derivatives and triazine derivatives; and compounds containing a nitrogen-containing six-membered ring structure such as quinoline derivatives, isoquinoline derivatives, and phenanthroline derivatives (including compounds having a phosphine oxide-based substituent on the heterocyclic ring). In an exemplary embodiment, the hole blocking layer may have a thickness of approximately 5 nm to 15 nm, and the electron transport layer may have a thickness of approximately 20 nm to 50 nm.

[0106] In an exemplary embodiment, the electron injection layer may be made of an alkali metal or metal, such as lithium fluoride (LiF), ytterbium (Yb), magnesium (Mg), or calcium (Ca), or a compound of these alkali metals or metals. In an exemplary embodiment, the electron injection layer may have a thickness of approximately 0.5 nm to 2 nm.

[0107] (5) Forming an encapsulation layer pattern. In an exemplary embodiment, forming an encapsulation layer pattern may include:

[0108] An encapsulation layer 6 is formed on the substrate 10 having the aforementioned pattern formed thereon. In an exemplary embodiment, the encapsulation layer 6 may be prepared by first depositing a first encapsulation film using an open mask on the substrate 1 having the aforementioned pattern formed thereon to form a first patterned layer. Subsequently, a second encapsulation material is printed using an inkjet printing process using an open mask to form a second patterned layer. Subsequently, a third encapsulation film is deposited using an open mask to form a third patterned layer. This completes the encapsulation layer pattern. The encapsulation layer 6 may also employ other structures, which are not limited herein.

[0109] In an exemplary embodiment, the first and third encapsulation films can be made of any one or more of silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON). They can be single-layer, multi-layer, or composite layers, ensuring that external water and oxygen cannot enter the light-emitting structure layer. Deposition methods such as chemical vapor deposition (CVD) or atomic layer deposition (ALD) can be used. The second encapsulation film can be made of an organic material, such as a resin, to cover the various film layers of the display substrate, improving structural stability and flatness.

[0110] After the above preparation, the structure of the display substrate obtained is as follows Figure 3 The display substrate may further include other film structures, such as a touch structure layer, a protective layer and other structures, which may be prepared according to actual needs and will not be described in detail here.

[0111] The present disclosure also provides a display device comprising the display substrate described in any of the above embodiments. The display device can be any product or component with a display function, such as an OLED display, a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, or a navigation system, but the present disclosure is not limited thereto.

[0112] The drawings in this disclosure only relate to the structures involved in this disclosure, and other structures may refer to general designs. In the absence of conflict, the embodiments of this disclosure, that is, the features in the embodiments, may be combined with each other to obtain new embodiments.

Claims

1. A display substrate, characterized in that: The display substrate includes a color filter layer, a color conversion layer, and a WOLED functional layer stacked on the substrate in sequence, wherein: The WOLED functional layer is configured to emit white light, which is emitted from the substrate after passing through the color conversion layer and the color filter layer. The WOLED functional layer includes a first blue organic light-emitting layer, a green organic light-emitting layer, a red organic light-emitting layer, and a second blue organic light-emitting layer stacked in a direction perpendicular to the substrate. The material of the green organic light-emitting layer includes a dual host material, and the HOMO energy level of at least one of the dual host materials is greater than or equal to 5.5 electron volts, so that in an initial state, the green light emission intensity of the phosphorescent light-emitting unit composed of the red light-emitting layer and the green light-emitting layer is stronger. The color filter layer includes a plurality of red color filter areas, green color filter areas, blue color filter areas and white color filter areas that are spaced apart; The color conversion layer includes a first color conversion region corresponding to the white color filter region and configured to convert a green light portion of the white light from the WOLED functional layer into red light.

2. The display substrate according to claim 1, wherein: The color conversion layer further includes at least one of a second color conversion region and a third color conversion region; wherein, The second color conversion region corresponds to the red color filter region and is configured to convert the blue light portion of the white light from the WOLED functional layer into red light; the third color conversion region corresponds to the green color filter region and is configured to convert the blue light portion of the white light from the WOLED functional layer into green light.

3. The display substrate according to claim 1, wherein The maximum emission wavelength of the material of the first color conversion zone is greater than or equal to 580 nanometers and less than or equal to 660 nanometers. The absorption spectrum of the material of the first color conversion zone overlaps with the green emission spectrum in the emission spectrum of the WOLED functional layer, and the area of ​​the overlapping portion is greater than 30% of the area of ​​the green emission spectrum.

4. The display substrate according to claim 3, wherein: The absorption spectrum of the material of the first color conversion region does not overlap with the blue light emission spectrum in the emission spectrum of the WOLED functional layer.

5. The display substrate according to claim 2, wherein: The maximum emission wavelength of the material of the second color conversion zone is greater than or equal to 580 nanometers and less than or equal to 660 nanometers. The absorption spectrum of the material of the second color conversion zone overlaps with the blue emission spectrum and the green emission spectrum in the emission spectrum of the WOLED functional layer, and the total overlapping area with the blue emission spectrum and the green emission spectrum is greater than 90% of the sum of the areas of the blue emission spectrum and the green emission spectrum.

6. The display substrate according to claim 2, wherein: The maximum emission wavelength of the material of the third color conversion zone is greater than or equal to 480 nanometers and less than or equal to 580 nanometers. The absorption spectrum of the material of the third color conversion zone overlaps with the blue emission spectrum in the emission spectrum of the WOLED functional layer, and the area of ​​the overlapping portion is greater than 90% of the area of ​​the blue emission spectrum.

7. The display substrate according to claim 1, wherein: The substrate includes a base and a driving structure layer disposed on the base. The driving structure layer includes a pixel driving circuit. The driving structure layer is configured to drive the WOLED functional layer to emit light.

8. The display substrate according to claim 1, wherein: The display substrate further includes an encapsulation layer, and the encapsulation layer is located on a side of the WOLED functional layer away from the substrate.

9. A display device, characterized in that: The display substrate comprises the display substrate according to any one of claims 1 to 8.

10. A method for preparing a display substrate, characterized in that: The method comprises: forming a color filter layer on the substrate, wherein the color filter layer comprises a plurality of red color filter areas, green color filter areas, blue color filter areas and white color filter areas that are spaced apart; forming a color conversion layer on the substrate, the color conversion layer comprising a first color conversion region, the first color conversion region corresponding to the white color filter region, and configured to convert a green portion of the white light from the WOLED functional layer into red light; forming a WOLED functional layer on the substrate, wherein the WOLED functional layer is configured to emit white light, and the white light is emitted from the substrate after passing through the color conversion layer and the color filter layer; The forming of the WOLED functional layer on the substrate comprises: A first blue organic light-emitting layer, a green organic light-emitting layer, a red organic light-emitting layer, and a second blue organic light-emitting layer are sequentially formed on the substrate; wherein the material of the green organic light-emitting layer includes a dual host material, and the HOMO energy level of at least one of the dual host materials is greater than or equal to 5.5 electron volts, so that in an initial state, the luminous intensity of green light in the phosphorescent light-emitting unit composed of the red light-emitting layer and the green light-emitting layer is stronger.

11. The preparation method according to claim 10, characterized in that: The color conversion layer further includes at least one of a second color conversion region and a third color conversion region; and forming the color conversion layer on the substrate includes: A first color conversion region, a second color conversion region, and / or a third color conversion region are formed on the substrate, respectively; wherein the second color conversion region corresponds to the red color filter region and is configured to convert the blue light portion of the white light from the WOLED functional layer into red light; and the third color conversion region corresponds to the green color filter region and is configured to convert the blue light portion of the white light from the WOLED functional layer into green light.

12. The preparation method according to claim 10, characterized in that After forming the WOLED functional layer on the substrate, the method further includes: forming an encapsulation layer on a side of the WOLED functional layer away from the substrate.

Images