Display substrate and display device

Abstract

A display substrate and a display device, the display substrate comprising a plurality of light emitting devices, an intrinsic emission spectrum of at least one light emitting device comprising a first spectral peak and a second spectral peak, the first spectral peak comprising a first color light, the second spectral peak comprising a second color light; the display substrate displaying the first color in a first viewing angle range smaller than a first viewing angle, the display substrate displaying the second color in a second viewing angle range larger than a second viewing angle; the viewing angle being an angle between a line of sight of a viewer and a normal line of a viewing area in the display substrate, the second viewing angle being larger than the first viewing angle. The exemplary embodiments of the present disclosure utilize color shift phenomenon, emit light of multiple colors by the light emitting devices, and utilize gain of light of different wavelengths at different viewing angles to make light of different colors exit at different viewing angle ranges, thus simplifying display of signals of multiple colors.

Description

Technical Field

[0001] This disclosure relates to, but is not limited to, display technology, and particularly to a display substrate and a display device. Background Technology

[0002] Organic Light Emitting Diode (OLED) displays are gaining increasing attention as a new type of flat panel display. OLEDs are active-matrix light-emitting devices, offering advantages such as high brightness, saturated color, ultra-thin design, wide viewing angles, low power consumption, extremely fast response times, and flexibility, effectively meeting users' personalized needs. With the continuous development of display technology, display devices using OLEDs as the light-emitting device and thin-film transistors (TFTs) for signal control have become the mainstream products in the display field. Summary of the Invention

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

[0004] This disclosure provides a display substrate and a display device that enable multi-color display.

[0005] This disclosure provides a display substrate, characterized in that it includes a plurality of light-emitting devices, at least one of which has an intrinsic emission spectrum including a first peak and a second peak, the first peak including a first color light and the second peak including a second color light; the display substrate displays the first color within a first viewing angle range smaller than a first viewing angle, and displays the second color within a second viewing angle range larger than a second viewing angle; the viewing angle is the angle between the viewer's line of sight and the normal to the viewing area in the display substrate, and the second viewing angle is larger than the first viewing angle.

[0006] In one exemplary embodiment, the display substrate displays a third color within a third viewing angle range that is greater than the first viewing angle and less than the second viewing angle.

[0007] In an exemplary embodiment, the wavelength of the first color light is greater than the wavelength of the second color light, and in the intrinsic emission spectrum of the light-emitting device, the maximum intensity of the first spectral peak is less than the maximum intensity of the second spectral peak.

[0008] In one exemplary embodiment, the first viewing angle ranges from 0° to 15°; the second viewing angle ranges from 55° to 65°; and the third viewing angle ranges from 25° to 40°.

[0009] In an exemplary embodiment, the display substrate includes a driving structure layer disposed on a substrate, a light-emitting structure layer disposed on the driving structure layer, and an encapsulation structure layer disposed on the light-emitting structure layer; the light-emitting structure layer includes an anode, a cathode, and an organic light-emitting layer disposed between the anode and the cathode; when the viewing angle is 0°, the wavelength corresponding to the peak of the microcavity gain spectrum of the microcavity formed by the anode and the cathode includes the wavelength of the first color light ±1%.

[0010] In an exemplary embodiment, the display substrate includes a driving structure layer disposed on a substrate, a light-emitting structure layer disposed on the driving structure layer, and an encapsulation structure layer disposed on the light-emitting structure layer; the light-emitting structure layer includes an anode, a cathode, and an organic light-emitting layer disposed between the anode and the cathode; the first color includes red, the second color includes green, the third color includes yellow, and the microcavity length of the microcavity formed by the anode and the cathode is 265 nm to 284 nm.

[0011] In an exemplary embodiment, the organic light-emitting layer includes a host material, a first color light-emitting material, and a second color light-emitting material, wherein the doping ratio of the second color light-emitting material is greater than the doping ratio of the first color light-emitting material.

[0012] In one exemplary embodiment, the doping ratio of the first color light-emitting material is less than or equal to 2%, and the doping ratio of the second color light-emitting material is greater than 2% and less than or equal to 5%.

[0013] This disclosure provides a display device including the display substrate described in any of the above embodiments.

[0014] In one exemplary embodiment, the display device further includes a driving device connected to the display substrate and capable of rotating or folding the display substrate.

[0015] This disclosure includes a display substrate and a display device. The display substrate includes a plurality of light-emitting devices. The intrinsic emission spectrum of at least one light-emitting device includes a first spectral peak and a second spectral peak. The first spectral peak includes a first color of light, and the second spectral peak includes a second color of light. Within a first viewing angle range smaller than a first viewing angle, the display substrate displays the first color. Within a second viewing angle range larger than a second viewing angle, the display substrate displays the second color. The viewing angle is the angle between the viewer's line of sight and the normal to the viewing area in the display substrate. The second viewing angle is larger than the first viewing angle.

[0016] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description and the drawings.

[0017] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0018] The accompanying drawings are provided to further understand the technical solutions of this disclosure and constitute a part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions.

[0019] Figure 1 A schematic diagram of a display substrate provided as an exemplary embodiment;

[0020] Figure 2 A schematic cross-sectional view of a display substrate is provided for an exemplary embodiment;

[0021] Figure 3A A schematic diagram of light-emitting energy transfer on a display substrate provided as an exemplary embodiment;

[0022] Figure 3B A schematic diagram of light-emitting energy transfer from a display substrate is provided as another exemplary embodiment;

[0023] Figure 4A A color trend diagram of a display substrate under different viewing angles is provided as an exemplary embodiment;

[0024] Figure 4B A color trend diagram of a display substrate under different viewing angles is provided as an exemplary embodiment;

[0025] Figure 5 Gain spectrum of light-emitting devices in a display substrate provided as an exemplary embodiment;

[0026] Figure 6 A spectrum of light emitted from a display substrate is provided as an exemplary embodiment.

[0027] Figure 7A and Figure 7B This is a schematic diagram of the structure of a display device according to an exemplary embodiment of the present disclosure;

[0028] Figures 7C to 7E This is a schematic diagram illustrating the rotation of a display device as an exemplary embodiment of the present disclosure;

[0029] Figure 8A and Figure 8B This is a schematic diagram of the structure of another display device according to an exemplary embodiment of the present disclosure;

[0030] Figures 8C to 8E This is a schematic diagram of another display device folding as an exemplary embodiment of the present disclosure. Detailed Implementation

[0031] The embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the embodiments of this disclosure and the features thereof can be combined arbitrarily with each other.

[0032] The steps illustrated in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases the steps shown or described may be performed in a different order than that presented here.

[0033] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0034] In the accompanying drawings, the size of the constituent elements, the thickness of the layers, or the area are sometimes exaggerated for clarity. Therefore, embodiments of this disclosure are not necessarily limited to these dimensions, and the shapes and sizes of the components in the drawings do not reflect true proportions. Furthermore, the drawings schematically illustrate ideal examples, and embodiments of this disclosure are not limited to the shapes or values ​​shown in the drawings.

[0035] The ordinal numbers “first,” “second,” “third,” etc., used in this disclosure are provided to avoid confusion among the constituent elements and do not indicate any order, quantity, or importance.

[0036] In this disclosure, for convenience, terms such as "middle," "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer" are used to indicate orientation or positional relationships in conjunction with the accompanying drawings. This is solely for the purpose of facilitating the description and simplification of the specification, and does not imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this disclosure. The positional relationships of the constituent elements may be appropriately varied depending on the direction in which each constituent element is described. Therefore, the disclosure is not limited to the terms used herein and may be appropriately replaced as appropriate.

[0037] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection, an indirect connection via an intermediate component, or a connection within two components. Those skilled in the art can understand the specific meaning of these terms in this disclosure according to the specific circumstances.

[0038] In this disclosure, a transistor is 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 the drain electrode (drain electrode terminal, drain region, or drain electrode) and the source electrode (source electrode terminal, source region, or source electrode), and current can flow through the drain electrode, the channel region, and the source electrode. In this disclosure, the channel region refers to the region through which current primarily flows.

[0039] In this disclosure, the first electrode can be the drain electrode and the second electrode can be the source electrode, or vice versa. In cases where transistors with opposite polarities are used or where the current direction changes during circuit operation, the functions of the "source electrode" and "drain electrode" are sometimes interchanged. Therefore, in this disclosure, the "source electrode" and "drain electrode" can be interchanged.

[0040] In this disclosure, "electrical connection" includes the situation where constituent elements are connected together by a component having a certain electrical function. There are no particular limitations on the "component having a certain electrical function," as long as it enables the transmission and reception of electrical signals between the connected constituent elements. Examples of "component having a certain electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other components with various functions.

[0041] In this disclosure, "parallel" refers to a state in which the angle formed by two straight lines is greater than or equal to -10° and less than 10°, and therefore also includes a state in which the angle is greater than or equal to -5° and less than 5°. In addition, "perpendicular" refers to a state in which the angle formed by two straight lines is greater than or equal to 80° and less than 100°, and therefore also includes a state in which the angle is greater than or equal to 85° and less than 95°.

[0042] In this disclosure, the terms "film" and "layer" can be interchanged. For example, sometimes "conductive layer" can be replaced with "conductive film". Similarly, sometimes "insulating film" can be replaced with "insulating layer".

[0043] The phrase "A and B are set on the same layer" in this disclosure means that A and B are formed simultaneously through the same patterning process. "The orthographic projection of B is within the range of the orthographic projection of A" means that the boundary of the orthographic projection of B falls within the boundary range of the orthographic projection of A, or the boundary of the orthographic projection of A overlaps with the boundary of the orthographic projection of B.

[0044] Structurally, a top-emitting OLED device can be viewed as a light source sandwiched within an optical interference cavity formed by a highly reflective mirror and a semi-transparent mirror. In an OLED display, each RGB sub-pixel can be considered such a device. Although at a normal viewing angle, the white image is controlled by gamma modulation, adjusting the RGB brightness ratio via electrical signals to achieve white balance, the different structures of the optical interference cavities of each RGB sub-pixel cause the brightness ratio to change at wider viewing angles. This further leads to a deviation of the white image's color coordinates at wider viewing angles from those at normal viewing angles, resulting in color shift at wider viewing angles. This color shift phenomenon is currently unavoidable in the industry due to the inherent structural limitations of OLED devices.

[0045] In this embodiment, the defect of large viewing angle coordinate deviation in the display substrate is utilized, and the degree of this large viewing angle coordinate deviation is amplified, so that the image displayed on the display substrate presents different colors when viewed from different angles. On the same display substrate, multiple colors can be displayed by controlling the rotation angle of the display substrate or the folding angle of the flexible folding screen, simplifying the signal display system.

[0046] Figure 1 This is a schematic diagram of a planar structure of a display substrate according to an exemplary embodiment of the present disclosure. Figure 1 As shown, the display substrate may include multiple pixel units P arranged in a matrix, at least one of the multiple pixel units P including a pixel driving circuit and a light-emitting device. The light-emitting device may include an organic light-emitting layer. The structures of the light-emitting devices of the multiple pixel units P may be identical, that is, the display substrate may contain only one pixel structure, which can eliminate the need for expensive high-precision metal masks (FMMs) and utilize only low-cost common metal masks (CMMs) shared by pixels for vacuum evaporation deposition of the organic light-emitting layer of the light-emitting device. In an exemplary embodiment, on a plane parallel to the display substrate, the cross-sectional shape of the light-emitting device in the pixel unit P may be rectangular, rhomboid, pentagonal, or hexagonal, and this disclosure is not limited thereto. The intrinsic emission spectrum of the light-emitting device includes a first spectral peak and a second spectral peak, the first spectral peak including a first color light, and the second spectral peak including a second color light. Within a first viewing angle range smaller than a first viewing angle, the display substrate displays the first color; within a second viewing angle range larger than a second viewing angle, the display substrate displays the second color; the viewing angle is the angle between the viewer's line of sight and the normal to the viewing area in the display substrate, and the second viewing angle is larger than the first viewing angle.

[0047] Exemplary embodiments of this disclosure utilize color shift phenomena to emit light of multiple colors through a light-emitting device, and utilize the gain of light of different wavelengths at different viewing angles to emit light of different colors at different viewing angles, thereby simplifying the display of multiple color signals.

[0048] In one exemplary embodiment, the display substrate displays a third color within a third viewing angle range that is greater than the first viewing angle and less than the second viewing angle.

[0049] Figure 2 This is a cross-sectional structural diagram of a display substrate provided as an exemplary embodiment of the present disclosure, illustrating the structure of two light-emitting units. For example... Figure 2 As shown, on a plane perpendicular to the display substrate, the display substrate may include a driving structure layer 103 disposed on a substrate 10, a light-emitting structure layer 104 disposed on the side of the driving structure layer 103 away from the substrate 10, and an encapsulation structure layer 105 disposed on the side of the light-emitting structure layer 104 away from the substrate 10. The light-emitting structure layer 104 of at least one light-emitting device may include an anode 21, an organic light-emitting layer 23, and a cathode 24, with the organic light-emitting layer 23 disposed between the anode 21 and the cathode 24.

[0050] In one exemplary embodiment, the organic light-emitting layer 23 may include a host material, a first-color light-emitting material, and a second-color light-emitting material. The first-color light-emitting material generates first-color light upon excitation, and the second-color light-emitting material generates second-color light upon excitation.

[0051] In an exemplary embodiment, the wavelength of the first color light can be greater than the wavelength of the second color light. In the intrinsic emission spectrum of the light-emitting device, the maximum intensity of the first spectral peak is less than the maximum intensity of the second spectral peak. That is, the maximum intensity of the first color light is less than the maximum intensity of the second color light. Specifically, the spectral peaks of the intrinsic emission spectrum of the light-emitting device include a main peak and secondary peaks, wherein the main peak includes the second color light and the secondary peak includes the first color light. In other words, in the intrinsic emission spectrum of the light-emitting device, the maximum intensity of the second color light is greater than the maximum intensity of the first color light. As the viewing angle increases, the emitted light blue-shifts. The microcavity gain spectrum can be set so that the gain intensity of the first color light is maximum at a viewing angle of 0°, and the maximum gain of the microcavity gain spectrum decreases as the viewing angle increases. The superposition of the microcavity gain spectrum and the intrinsic emission spectrum can make the intensity of the emitted light more balanced under different viewing angles, improving the display uniformity under different viewing angles.

[0052] In one exemplary embodiment, the doping ratio of the first color light-emitting material can be less than the doping ratio of the second color light-emitting material. The luminous intensity is related to the doping ratio; if the doping ratio of the first color light-emitting material is less than that of the second color light-emitting material, then the intensity of the first color light is less than the intensity of the second color light. However, this embodiment is not limited to this; the doping ratio of the first color light-emitting material can be greater than or equal to the doping ratio of the second color light-emitting material. In the exemplary embodiment, the doping ratio refers to the ratio of the mass of the doped material to the mass of the light-emitting layer, i.e., a mass percentage.

[0053] In one exemplary embodiment, the first color can be red, and the second color can be green. However, this embodiment is not limited to this and can use other colors. The spectral peaks of the intrinsic emission spectrum of the light-emitting device can include red light and green light. Specifically, the main peak can include green light, and the secondary peaks can include red light; that is, in the intrinsic emission spectrum, the maximum intensity of green light is greater than the maximum intensity of red light.

[0054] The process of organic materials emitting light is the process by which electrons transition from a high energy level to a low energy level and release energy (S1->S0 or T1->S0). The released energy is visible light. Here, S0 is the ground state energy level, and S1 (first electron excited singlet state) and T1 (first electron excited triplet state) are excited state energy levels. The luminescence process is as follows:

[0055] Electrons and holes meet in the light-emitting layer and recombine, generating excitons. These excitons migrate under the influence of an electric field, transferring energy to the doped material in the light-emitting layer. Electrons in the doped material absorb energy and transition from the ground state to the excited state. Because the excited state is unstable, the electrons will transition back to the ground state, releasing energy and generating photons. Depending on the energy level of the excited state of the light-emitting material, the electrons release photons of different energies during their transition back to the ground state. The energy determines the wavelength of the light.

[0056] Taking an example where the main peak is green and the secondary peaks are red. Figure 3A As shown, when the doping ratio of the red luminescent material is less than or equal to 1%, the charge carriers are captured and recombine by the host material, causing the host material to become excited (S1 or T1). Among them, 25% becomes S1 state and 75% becomes T1 state. The excitation energy of the host material is transferred to the green luminescent material, and the green luminescent material becomes excited (the energy transfer mode is S1->S1 or T1->T1, T1->S1). The green luminescent material transitions from S1 state back to S0 state and emits green light. The excitation energy of the green luminescent material is transferred to the red luminescent material (S1->S1), and the red luminescent material transitions from S1 state back to S0 state and emits red light.

[0057] like Figure 3BAs shown, when the doping ratio of the red luminescent material is greater than 1% and less than or equal to 2%, the charge carriers are captured and recombine by the host material, causing the host material to become excited (S1 or T1). Among them, 25% becomes S1 state and 75% becomes T1 state. The excitation energy of the host material is transferred to the green luminescent material, and the green luminescent material becomes excited (energy transfer mode is S1->S1, T1->T1, S1->T1). The green luminescent material transitions from T1 state back to S0 state and emits green light. The excitation energy of the green luminescent material is transferred to the red luminescent material (energy transfer mode is S1->S1, T1->T1, S1->T1). The red luminescent material transitions from T1 state back to S0 state and emits red light.

[0058] In one exemplary embodiment, the doping ratio of the first color light-emitting material can be less than or equal to 2%, and the doping ratio of the second color light-emitting material can be less than or equal to 2%. Taking red as the first color and green as the second color as an example, the doping ratio of the red light-emitting material can be less than or equal to 2%, and the doping ratio of the green light-emitting material can be greater than 2% and less than or equal to 5%. However, the embodiments of this disclosure are not limited to this, and the doping ratio can be changed according to the design requirements of the intrinsic emission spectrum.

[0059] In an exemplary embodiment, the anode 21 may include a reflective electrode, and the cathode 24 may include a semi-transparent, semi-reflective electrode, forming a top-emitting OLED light-emitting device. Structurally, a top-emitting OLED light-emitting device can be viewed as a light source disposed within an optical cavity structure formed by the reflective electrode and the semi-transparent, semi-reflective electrode. Light continuously reflects back and forth within the optical cavity structure, achieving microcavity resonance and thus enhancing the light intensity of specific wavelengths in the emitted light, i.e., the microcavity effect. In the OLED display substrate, each light-emitting device has such an optical interference cavity. The distance between the anode, which reflects light, and the cathode, which reflects and transmits light, is called the microcavity length. In an exemplary embodiment, the microcavity length can be the thickness of the organic light-emitting layer between the anode and the cathode. Due to the strong reflection effect of the reflective electrode, the light emitted directly from the light-emitting layer interferes with the light reflected by the reflective electrode. This not only broadens the spectrum of light near the resonant wavelength corresponding to the microcavity length, thereby improving color purity and color gamut, but also enhances the light intensity near the resonant wavelength corresponding to the microcavity length, thereby increasing brightness.

[0060] In an exemplary embodiment, the microcavity effect of each light-emitting device satisfies δ = 2j(λ / 2) = 2ndcosβ, where δ is the microcavity phase difference, j is an integer, λ is the wavelength of the emitted light from the light-emitting device, n is the average refractive index of the organic light-emitting layer in the microcavity, d is the microcavity length, and β is the reflection angle. From the formula for the microcavity optical path difference, it can be seen that the microcavity length d is proportional to the emitted light wavelength λ. By designing the distance between the anode and cathode in the light-emitting device or the thickness of the organic light-emitting layer (i.e., the microcavity length), the emission of light near the resonant wavelength corresponding to the cavity length can be enhanced in each light-emitting device. For a given device structure, the average refractive index n and the microcavity length d are fixed values. As the reflection angle β increases, the wavelength λ decreases; that is, as the viewing angle deviating from the direct view increases, the emitted light from the microcavity structure exhibits a blue shift.

[0061] In one exemplary embodiment, an incomplete energy transfer system from a green light-emitting material to a red light-emitting material is used to ensure that the primary peak of the intrinsic emission spectrum includes green light (the spectrum of the green light-emitting material), and the secondary peak includes red light (the spectrum of the red light-emitting material). Then, the gain spectral positions of the microcavity are designed at different viewing angles to achieve red, yellow, and green tricolor display from different perspectives.

[0062] In one exemplary embodiment, the first viewing angle range can be 0° to 15°; the second viewing angle range can be 55° to 65°; and the third viewing angle range can be 25° to 40°.

[0063] Figure 4A and Figure 4B The chromaticity diagrams of a display substrate provided as an exemplary embodiment under different viewing angles employ the CIE 1931 color space. The display substrate may include multiple light-emitting devices arranged in a matrix. For example... Figure 4B As shown, during the change in viewing angle θ from 0° to 90°, the display substrate changes from a red image to a yellow image, and then from a yellow image to a green image. The color trajectory is a straight line connecting the red, yellow, and green chromaticity points. The main color tones involved in the viewing angle change mainly include red, yellow, and green hues, and each color display has a large angular tolerance. Viewing angle θ refers to the angle between the observer's line of sight S to the display substrate and the normal O of the viewing area on the display substrate. When the viewing angle θ is between 0° and 15°, the display substrate displays red. For example, as... Figure 4A As shown, the color coordinates for a viewing angle θ = 0° are approximately (0.632, 0.358). At viewing angles θ = 25° to 40°, the display substrate displays a yellow color. For example, as... Figure 4A As shown, the color coordinates for a viewing angle θ = 35° are approximately (0.441, 0.521). At viewing angles θ = 55° to 65°, the display substrate displays red. For example, as... Figure 4A As shown, the color coordinates of the viewing angle θ = 60° are approximately (0.285, 0.656).

[0064] In an exemplary embodiment, when the viewing angle is 0°, the wavelength λ2 corresponding to the peak value of the microcavity gain spectrum of the microcavity formed by the anode and cathode may include λ1 ± 1%. λ1 is the wavelength of the first color light. That is, the microcavity enhances light with wavelength λ2, i.e., it can enhance the first color light or light with a wavelength close to that of the first color light.

[0065] Figure 5 This is a gain spectrum of a light-emitting device in a display substrate provided as an exemplary embodiment. The relative positional relationship between the intrinsic emission spectrum of the light-emitting device and the microcavity gain spectrum is as follows: Figure 5 As shown. In this embodiment, the intrinsic emission spectrum includes a main peak and a secondary peak. The main peak includes green light, and the secondary peak includes red light. The peak value of the secondary peak corresponds to a wavelength of 594 nm. At a viewing angle θ = 0°, the microcavity gain spectrum can be set at the peak of the secondary peak of the intrinsic emission spectrum. As the viewing angle increases, the microcavity gain spectrum gradually shifts towards smaller wavelengths. Through this optical structure design of the light-emitting device, the final trend of the emitted light is as follows: Figure 6 As shown, with increasing viewing angle, the emitted light changes from red to yellow and then to green. At a positive viewing angle, the wavelength corresponding to the peak of the microcavity gain spectrum can be set at 594 nm, the wavelength corresponding to the peak of the secondary peak of the intrinsic emission spectrum. Correspondingly, the microcavity length A1 can be 270 nm. After the microcavity significantly enhances the red light band, the following effect is obtained: Figure 6 The red light spectrum corresponding to 0° is shown, indicating that the display system displays a red signal at a normal viewing angle. At 35°, the wavelength corresponding to the peak of the microcavity gain spectrum is significantly blue-shifted to around 576nm. At this point, the microcavity amplifies the wavelength at the midpoint between the red and green spectra in the intrinsic emission spectrum, resulting in significant enhancement at 576nm, as shown below. Figure 6 The mid-yellow light spectrum; at 60°, the wavelength corresponding to the peak of the microcavity gain spectrum is blue-shifted to 549 nm. At this point, the green spectrum in the intrinsic emission spectrum is significantly enhanced by the microcavity, thus obtaining... Figure 6 Mid-green light spectrum. That is, using the same display substrate, the same pixel structure, and the same luminescent material, at different viewing angles, through the microcavity gain at different wavelengths, the intrinsic emission spectrum of the main material, green luminescent material, and red luminescent material in the incomplete energy transfer system is increased at different positions, achieving color transitions of red, yellow, and green images at 0°, 35°, and 60°.

[0066] In one exemplary embodiment, the wavelength corresponding to the peak value of the secondary peak of the intrinsic emission spectrum can be other values, such as 590 nm to 620 nm. That is, the wavelength λ1 of the first color light can be 590 nm to 620 nm. When the viewing angle is 0°, the wavelength corresponding to the peak value of the microcavity gain spectrum of the microcavity formed by the anode and cathode can be λ1 ± 1%, that is, the wavelength corresponding to the peak value of the microcavity gain spectrum of the microcavity formed by the anode and cathode can be 584 nm to 626 nm, and the corresponding microcavity length is 265 nm to 284 nm. However, the embodiments of this disclosure are not limited to this. For example, the wavelength λ1 of the first color light can be 600 nm to 630 nm. When the viewing angle is 0°, the wavelength corresponding to the peak value of the microcavity gain spectrum of the microcavity formed by the anode and cathode can be 594 nm to 636 nm, and the corresponding microcavity length is 270 nm to 289 nm.

[0067] In the intrinsic emission spectrum, the main peak is green, the secondary peak is red, and the intensity of yellow light is between the main and secondary peaks. In the microcavity gain spectrum, the gain of red light is the largest when the viewing angle θ = 0°, and the gain of green light is the largest when the viewing angle θ = 60°. The gain intensity of red light at θ = 0° is greater than that of green light at θ = 60°. The gain intensity of yellow light at θ = 35° is between that of red light at θ = 0° and that of green light at θ = 60°. After the microcavity gain spectrum and the intrinsic emission spectrum are superimposed, the intensity of red light at θ = 0°, the intensity of yellow light at θ = 35°, and the intensity of green light at θ = 60° in the emitted light are basically the same, which can improve the brightness uniformity of the display substrate when displaying different colors.

[0068] Figure 6 This is a spectrum of light emitted from a display substrate, as an exemplary embodiment of this disclosure. Figure 6 As shown, near a viewing angle θ = 0° (normal viewing angle), the display substrate shows a red image, with corresponding color coordinates of approximately (0.632, 0.358). Near a viewing angle θ = 35°, the display substrate shows a yellow image, with corresponding color coordinates of approximately (0.441, 0.521). Near a viewing angle θ = 60°, the display substrate shows a green image, with corresponding color coordinates of approximately (0.285, 0.656).

[0069] The technical solution of this embodiment is further illustrated below through the substrate fabrication process. The "patterning process" mentioned in this embodiment includes deposition of a film layer, coating with photoresist, mask exposure, development, etching, and photoresist stripping, which are mature fabrication processes in related technologies. The "photolithography process" mentioned in this embodiment includes coating of a film layer, mask exposure, and development, which are mature fabrication processes in related technologies. Deposition can employ known processes such as sputtering, evaporation, and chemical vapor deposition; coating can employ known coating processes; and etching can employ known methods, without specific limitations. In the description of this embodiment, it should be understood that a "thin film" refers to a thin film made of a certain material on a substrate using a deposition or coating process. If the "thin film" does not require a patterning process or photolithography process during the entire fabrication process, it can also be called a "layer." If the "thin film" requires a patterning process or photolithography process during the entire fabrication process, it is called a "thin film" before the patterning process and a "layer" after the patterning process. The "layer" after the patterning process or photolithography process contains at least one "pattern."

[0070] In one exemplary embodiment, the fabrication process of the display substrate includes the following operations:

[0071] (1) A driving structure layer 103 is formed on the substrate 10. The driving structure layer 103 may include a transistor consisting of an active layer, a gate electrode, a source electrode and a drain electrode. The transistor may be a driving transistor in a pixel driving circuit. The driving transistor may be a thin film transistor (TFT).

[0072] (2) A light-emitting structure layer 104 is formed on the driving structure layer 103;

[0073] In an exemplary embodiment, forming a light-emitting structure layer 104 on the driving structure layer 103 may include:

[0074] A conductive thin film is deposited on the substrate on which the aforementioned pattern is formed, and the conductive thin film is patterned by a patterning process to form a conductive layer pattern. The conductive layer pattern includes at least an anode 21 disposed in each light-emitting device. The conductive thin film can be a single layer of transparent conductive material, such as indium tin oxide (ITO) or indium zinc oxide (IZO), or the conductive thin film can be a composite layer of metal material and transparent conductive material, such as Ag / ITO, Ag / IZO or ITO / Ag / ITO, etc.

[0075] A pixel definition film is coated on the substrate with the aforementioned pattern. The pixel definition film is then exposed and developed using a patterning process to form a pixel definition (PDL) layer. Within each light-emitting device, a pixel opening is formed on the pixel definition layer. The pixel definition film within the pixel opening is developed away, exposing the surface of the anode. In an exemplary embodiment, the shape of the pixel opening in a plane parallel to the substrate can be square, rectangular, circular, elliptical, or hexagonal, etc., and can be set according to actual needs; this disclosure does not limit this. In an exemplary embodiment, the pixel definition film can be made of materials such as polyimide, acrylic, or polyethylene terephthalate.

[0076] An organic light-emitting layer 23 and a cathode 24 are sequentially formed on the substrate on which the aforementioned pattern is formed. The organic light-emitting layer 23 is connected to the anode 21 within the pixel opening, and the cathode 24 is formed on and connected to the organic light-emitting layer 23. The cathodes 24 of multiple light-emitting devices can be an integral structure. In an exemplary embodiment, the cathode can be made of a metallic material, such as magnesium (Mg), silver (Ag), or aluminum (Al), or an alloy material.

[0077] Thus, the pattern of the light-emitting structure layer 104 is completed on the driving structure layer 103. In an exemplary embodiment, the anode 21, the organic light-emitting layer 23, and the cathode 24 in the light-emitting structure layer 104 constitute an OLED light-emitting device, and the organic light-emitting layer 23 emits light of corresponding grayscale under the driving of the anode 21 and the cathode 24.

[0078] In an exemplary embodiment, the organic light-emitting layer 23 in the OLED light-emitting device may include a hole injection layer (HIL), a hole transport layer (HTL), an electron block layer (EBL), an emitting layer (EML), a hole block layer (HBL), an electron transport layer (ETL), and an electron injection layer (EIL).

[0079] To reduce process complexity and improve yield, the hole injection layer and hole transport layer on one side of the light-emitting layer can be common layers, as can the electron injection layer and electron transport layer on the other side. In an exemplary embodiment, any one or more of the hole injection layer, hole transport layer, electron injection layer, and electron transport layer can be fabricated in a single process (single vapor deposition process or single inkjet printing process), but isolation is achieved through surface steps of the formed film layers or through surface treatment. For example, any one or more of the hole injection layer, hole transport layer, electron injection layer, and electron transport layer corresponding to adjacent light-emitting devices can be isolated. In an exemplary embodiment, the organic light-emitting layer can be formed by vapor deposition using a general-purpose metal mask (also known as an open mask) or by inkjet printing.

[0080] In an exemplary embodiment, an OLED light-emitting device can be fabricated using the following method: A hole injection layer and a hole transport layer are sequentially deposited using an open mask to form a common layer of hole injection and hole transport layers on the display substrate. This means that the hole injection layers of all light-emitting devices are interconnected, and the hole transport layers of all light-emitting devices are interconnected. The hole injection layer and the hole transport layer have approximately the same area but different thicknesses. An electron blocking layer and a light-emitting layer are deposited using an open mask. The electron blocking layers and light-emitting layers of adjacent light-emitting devices may have a small amount of overlap (e.g., the overlapping portion occupies less than 10% of the area of ​​their respective light-emitting layer patterns) or may be isolated. A hole blocking layer, an electron transport layer, an electron injection layer, and a cathode are sequentially deposited using an open mask to form a common layer of hole blocking layer, electron transport layer, electron injection layer, and cathode on the display substrate. This means that the hole blocking layers of all light-emitting devices are interconnected, the electron transport layers of all light-emitting devices are interconnected, the electron injection layers of all light-emitting devices are interconnected, and the cathodes of all light-emitting devices are interconnected.

[0081] In exemplary embodiments, one or more of the hole injection layer, hole transport layer, hole blocking layer, electron transport layer, electron injection layer, and cathode have continuous orthogonal projections onto the substrate. In some examples, at least one of the hole injection layer, hole transport layer, hole blocking layer, electron transport layer, electron injection layer, and cathode of at least one row or column of light-emitting devices is connected. In some examples, at least one of the hole injection layer, hole transport layer, hole blocking layer, electron transport layer, electron injection layer, and cathode of multiple light-emitting devices is connected.

[0082] In an exemplary embodiment, since the hole blocking layer is a common layer while the light-emitting layers of different light-emitting devices are isolated, the orthographic projection of the hole blocking layer on the substrate includes the orthographic projection of the light-emitting layer on the substrate, and the area of ​​the hole blocking layer is larger than the area of ​​the light-emitting layer. Because the hole blocking layer is a common layer, the orthographic projection of the hole blocking layer on the substrate includes the orthographic projections of the light-emitting regions of at least two light-emitting devices on the substrate. In an exemplary embodiment, the orthographic projections of the light-emitting layers of at least some of the light-emitting devices on the substrate overlap with the orthographic projections of the pixel driving circuits on the substrate.

[0083] In an exemplary embodiment, the electron blocking layer can serve as a microcavity adjustment layer for the light-emitting device. By designing the thickness of the electron blocking layer, the thickness of the organic light-emitting layer between the cathode and anode can be made to meet the aforementioned microcavity length design. In an exemplary embodiment, the thickness of the electron blocking layer can be controlled by adjusting the evaporation rate and evaporation time. The process is simple and can be achieved using mature fabrication techniques.

[0084] In some exemplary embodiments, the hole transport layer, hole blocking layer or electron transport layer in the organic light-emitting layer can be used as the microcavity conditioning layer of the light-emitting device, and this disclosure does not limit it.

[0085] In other exemplary embodiments, the microcavity conditioning layer may include any one or more of the following: a hole transport layer, an electron blocking layer, a hole blocking layer, and an electron transport layer.

[0086] In an exemplary embodiment, the host material and the guest material can be deposited together by 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 adjusted by controlling the evaporation rate of the guest material or by controlling the ratio of the evaporation rates of the host material and the guest material during the evaporation process.

[0087] (3) An encapsulation structure layer 105 is formed on the light-emitting structure layer.

[0088] The encapsulation structure layer 105 may include a first encapsulation layer, a second encapsulation layer, and a third encapsulation layer stacked together, forming an inorganic / organic / inorganic material stacked structure. The organic material layer is disposed between the two inorganic material layers to ensure that external moisture cannot enter the light-emitting structure layer. In an exemplary embodiment, the thickness of the first encapsulation layer may be approximately 800 nm to 1200 nm, the thickness of the second encapsulation layer may be approximately 100,000 nm to 150,000 nm, and the thickness of the third encapsulation layer may be approximately 800 nm to 1200 nm.

[0089] As can be seen from the structure and fabrication process of the display substrate in the exemplary embodiments of this disclosure, the exemplary embodiments of this disclosure utilize the color shift phenomenon to emit light of multiple colors through the light-emitting layer. By amplifying light of different wavelengths at different viewing angles through a microcavity, different colors of light are emitted from the display substrate at different viewing angles. As the viewing angle increases, the emitted light from the display substrate changes from red to yellow, and from yellow to green. Furthermore, the light-emitting devices of the display substrate are identical, eliminating the need for high-precision metal masks and resulting in low cost.

[0090] This disclosure also provides a display device, including the aforementioned display substrate. In an exemplary embodiment, the display device may be a red-yellow-green signal display device.

[0091] In one exemplary embodiment, the display device may further include a driving device connected to the display substrate and capable of rotating or folding the display substrate.

[0092] In one exemplary embodiment, the display device may include a controller that outputs a control signal to the driving device, the control signal indicating angle information; the driving device, under the control of the control signal, causes the display substrate to rotate or fold at the angle indicated by the angle information.

[0093] Figure 7A and Figure 7B This is a schematic diagram of the structure of a display device according to an exemplary embodiment of the present disclosure. Figure 7A This is a side view diagram. Figure 7B This is a forward-facing diagram. For example... Figure 7A and Figure 7B As shown, the display device can be a red-yellow-green signal display device, which may include a display device 200 and a first driving device 300. The display device 200 may include the aforementioned display substrate, which may be a rigid display substrate. The first driving device 300 is configured to rotate the display device 200, and the rotating display device 200 presents images of different colors to the viewer R. In an exemplary embodiment, the first driving device 300 may be a rotation mechanism connected to the display device 200 and configured to rotate the display device 200. For example, the rotation mechanism may include at least a rotation shaft, which is disposed in the middle of the display device 200, and the display device 200 rotates about the rotation shaft.

[0094] Figures 7C to 7E This is a schematic diagram illustrating the rotation of a display device as an exemplary embodiment of this disclosure. When the display device 200 is not rotated, the display surface of the display device 200 faces the viewer R, and the normal of the display surface is parallel to the viewer R's line of sight S (i.e., viewing angle θ = 0°). The image presented to the viewer R by the display surface is a red image, such as... Figure 7A and Figure 7CAs shown. When the display device 200 deflects α1 = 35°, the angle between the normal of the display surface in the display device 200 and the viewer R's line of sight S is 35° (i.e., viewing angle θ = 35°), and the image presented to the viewer R by the display surface is a yellow image, as shown. Figure 7A and Figure 7D As shown. When the display device 200 deflects α2 = 60°, the angle between the normal of the display surface in the display device 200 and the viewer R's line of sight S is 60° (i.e., viewing angle θ = 60°), and the image presented to the viewer R by the display surface is a green image, as shown. Figure 7A and Figure 7E As shown.

[0095] The exemplary embodiments of this disclosure utilize the characteristic that the display color tone of the display device changes with the viewing angle to form a red, yellow, and green signal display device. By simply controlling the rotation angle of the display device, the red, yellow, and green signals can be displayed using a single display screen, which can reduce the number of signal lights and simplify the design.

[0096] The red, yellow, and green signal display device of the exemplary embodiments disclosed herein is merely an illustrative example. In the exemplary embodiments, the corresponding structure and display method can be changed according to actual needs. For example, the planar shape of the display device can be other shapes. Furthermore, the rotating shaft can be located in other positions of the display device or used in other ways to rotate the display device, etc., and this disclosure does not impose specific limitations herein.

[0097] Figure 8A and Figure 8B This is a schematic diagram of the structure of another display device according to an exemplary embodiment of the present disclosure. Figure 8A This is a side view diagram. Figure 8B This is a forward-facing diagram. For example... Figure 8A and Figure 8B As shown, the display device can be a red-yellow-green signal display device, which may include a display device 200 and a second driving device 400. The display device 200 may include the aforementioned display substrate, which may be a flexible display substrate. The second driving device 400 is configured to fold the display device 200, and the folded display device 200 presents images of different colors to the viewer R. In an exemplary embodiment, the second driving device 400 may be a folding mechanism, connected to the display device 200 and configured to fold the display device 200. For example, the folding mechanism may include at least a folding axis, which is disposed in the middle of the display device 200, and the display device 200 folds around the folding axis.

[0098] Figures 8C to 8EThis is a schematic diagram illustrating another folded display device according to an exemplary embodiment of the present disclosure. When the display device 200 is not folded, the display surface of the display device 200 faces the viewer R, the normal of the display surface is parallel to the viewer R's line of sight S (i.e., viewing angle θ = 0°), and the image presented to the viewer R is a red image, such as... Figure 8A and Figure 8C As shown. When the display device 200 is folded at α1 = 35°, the angle between the normal of the display surface in the display device 200 and the viewer R's line of sight S is 35° (i.e., viewing angle θ = 35°), and the image presented to the viewer R is a yellow image, as shown. Figure 8A and Figure 8D As shown. When the display device 200 is folded α2 = 60°, the angle between the normal of the display surface in the display device 200 and the viewer R's line of sight S is 60° (i.e., viewing angle θ = 60°), and the image presented to the viewer R by the display surface is a green image, as shown. Figure 8A and Figure 8E As shown.

[0099] The exemplary embodiments of this disclosure utilize the characteristic that the display color tone of the display device changes with the viewing angle to form a red, yellow, and green signal display device. By simply controlling the folding angle of the display device, the red, yellow, and green signals can be displayed using a single display screen, which can reduce the number of signal lights and simplify the design.

[0100] The red, yellow, and green signal display device of the exemplary embodiments disclosed herein is merely an illustrative example. In the exemplary embodiments, the corresponding structure and display method can be changed according to actual needs. For example, the planar shape of the display device can be other shapes. Furthermore, the folding axis can be set in other positions of the display device or used in other ways to fold the display device, etc., and this disclosure does not impose specific limitations herein.

[0101] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes to the form and details of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection of this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A display substrate, characterized in that, The device includes multiple light-emitting devices, at least one of which has an intrinsic emission spectrum comprising a first peak and a second peak. The first peak includes a first color of light, and the second peak includes a second color of light. The wavelength of the first color of light is greater than the wavelength of the second color of light. In the intrinsic emission spectrum of the light-emitting device, the maximum intensity of the first peak is less than the maximum intensity of the second peak. The light-emitting device includes an anode and a cathode, and an organic light-emitting layer disposed between the anode and the cathode. The organic light-emitting layer includes a host material, a first color light-emitting material, and a second color light-emitting material, wherein the doping ratio of the second color light-emitting material is greater than the doping ratio of the first color light-emitting material. The anode and cathode form a microcavity. The microcavity gain spectrum ensures that the gain intensity of the first color light is maximized at a viewing angle of 0°, and the maximum gain of the microcavity gain spectrum decreases as the viewing angle increases. The superposition of the microcavity gain spectrum and the intrinsic emission spectrum balances the intensity of the emitted light at different viewing angles. Within a first viewing angle range smaller than the first viewing angle, the display substrate displays the first color; within a second viewing angle range larger than the second viewing angle, the display substrate displays the second color; and within a third viewing angle range larger than the first viewing angle and smaller than the second viewing angle, the display substrate displays the third color. By utilizing the color shift phenomenon, different colors of light are emitted at different viewing angles. The viewing angle is the angle between the viewer's line of sight and the normal of the viewing area in the display substrate, and the second viewing angle is larger than the first viewing angle.

2. The display substrate according to claim 1, characterized in that, The first viewing angle ranges from 0° to 15°; the second viewing angle ranges from 55° to 65°; and the third viewing angle ranges from 25° to 40°.

3. The display substrate according to claim 1 or 2, characterized in that, The display substrate includes a driving structure layer disposed on a substrate, a light-emitting structure layer disposed on the driving structure layer, and an encapsulation structure layer disposed on the light-emitting structure layer; the light-emitting structure layer includes an anode, a cathode, and an organic light-emitting layer disposed between the anode and the cathode; When the viewing angle is 0°, the wavelength corresponding to the peak of the microcavity gain spectrum of the microcavity formed by the anode and cathode includes the wavelength of the first color light ±1%.

4. The display substrate according to claim 1 or 2, characterized in that, The display substrate includes a driving structure layer disposed on a substrate, a light-emitting structure layer disposed on the driving structure layer, and an encapsulation structure layer disposed on the light-emitting structure layer; the light-emitting structure layer includes an anode, a cathode, and an organic light-emitting layer disposed between the anode and the cathode; the first color includes red, the second color includes green, and the third color includes yellow, and the microcavity length of the microcavity formed by the anode and the cathode is 265nm to 284nm.

5. The display substrate according to claim 1, characterized in that, The doping ratio of the first color light-emitting material is less than or equal to 2%, and the doping ratio of the second color light-emitting material is greater than 2% and less than or equal to 5%.

6. A display device, characterized in that, The device includes a display substrate as described in any one of claims 1 to 5 and a driving device, wherein the driving device is connected to the display substrate and causes the display substrate to rotate or fold, and the display device is a red-yellow-green signal display device.

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