Display substrate and display device

Abstract

The display substrate includes: a backplane, an anode layer, a first auxiliary layer, a first light-emitting layer, a second auxiliary layer, a plurality of second light-emitting layers of at least two different colors, a third auxiliary layer, and a cathode layer. The first auxiliary layer includes a number of film layers stacked in sequence, each having an optical thickness of L1, where L1 satisfies the following equation (aa). The second auxiliary layer includes a number of film layers stacked in sequence, each having an optical thickness of L2, where L2 satisfies the following equation (bb). The third auxiliary layer includes a number of film layers stacked in sequence, each having an optical thickness of L3, where L3 satisfies the following equation (cc). L1, L2, and L3 satisfy the following equation (dd).

Description

[0001] This application claims priority to Chinese patent application No. 202210798416.7, filed on July 8, 2022, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present disclosure relates to the field of display technology, and in particular to a display substrate and a display device. Background Art

[0003] OLED (Organic Light Emitting Diode) displays utilize organic light-emitting diodes (OLEDs). They are currently widely used due to their superior properties, including the lack of a backlight, high contrast, thinness, wide viewing angle, fast response time, compatibility with flexible panels, wide operating temperature range, and relatively simple structure and manufacturing process. Summary of the Invention

[0004] An object of the embodiments of the present disclosure is to provide a display substrate and a display device for improving the luminance and color purity of the display substrate.

[0005] To achieve the above objectives, the embodiments of the present disclosure provide the following technical solutions:

[0006] On the one hand, a display substrate is provided. The display substrate includes: a backplane and an anode layer, a first auxiliary layer, a first light-emitting layer, a second auxiliary layer, a plurality of second light-emitting layers of at least two different colors, a third auxiliary layer and a cathode layer stacked in sequence on the backplane. A microcavity is formed between the anode layer and the cathode layer. The first light-emitting layer is arranged between the first auxiliary layer and the second auxiliary layer. The plurality of second light-emitting layers are arranged between the second auxiliary layer and the third auxiliary layer. Wherein, the first auxiliary layer includes a film layers stacked in sequence, the second auxiliary layer includes b film layers stacked in sequence, and the third auxiliary layer includes c film layers stacked in sequence, and a, b, and c are all positive integers. The optical thickness of the a film layer, the optical thickness of the b film layer, and the optical thickness of the c film layer satisfy the formula:

[0007]

[0008] is the average refractive index of the film between the anode layer and the cathode layer, The range of r is 1.7~2.0. h is the thickness of the hth film layer among the a film layers, r i is the thickness of the i-th film layer among the b film layers, and rj is the thickness of the j-th film layer among the c film layers.

[0009] The display substrate provided in some embodiments of the present disclosure can increase the luminous brightness of the display substrate by providing a first auxiliary layer, a second auxiliary layer, and a third auxiliary layer so that the first light-emitting layer and the second light-emitting layer form a series light-emitting device. In addition, a microcavity can be formed between the anode layer and the cathode layer of the display substrate, and the light emitted by the first light-emitting layer and the second light-emitting layer can produce a microcavity effect in the microcavity, thereby enhancing the luminous intensity of the emitted light, narrowing the spectrum of the emitted light, and improving the luminous efficiency of the light-emitting device. By making the optical thickness of the a film layers included in the first auxiliary layer, the optical thickness of the b film layers included in the second auxiliary layer, and the optical thickness of the c film layers included in the third auxiliary layer satisfy the formula:

[0010]

[0011] The color purity of light emitted by the light-emitting devices in the display substrate can be improved. Therefore, the display substrate disclosed herein can reduce the need for filters and improve luminous efficiency. Furthermore, the display substrate can reduce power consumption at higher brightness levels and increase the lifespan of the light-emitting devices.

[0012] In some embodiments, the plurality of second light-emitting layers include: a plurality of second blue light-emitting layers, a plurality of second red light-emitting layers, and a plurality of second green light-emitting layers. The wavelength of light emitted by the first light-emitting layer is smaller than the wavelength of light emitted by the second light-emitting layer of at least one color.

[0013] In some embodiments, the first light-emitting layer includes a first guest material, the second light-emitting layer includes a second guest material, and the emission spectrum of the first guest material at least partially overlaps with the absorption spectrum of the second guest material of the second light-emitting layer of at least one color.

[0014] In some embodiments, an overlap between the emission spectrum of the first guest material and the absorption spectrum of the second guest material is greater than or equal to 60% of a wavelength range of the emission spectrum of the first guest material.

[0015] In some embodiments, an overlap between the emission spectrum of the first guest material and the absorption spectrum of the second guest material is greater than or equal to 60% of a wavelength range of the absorption spectrum of the second guest material.

[0016] In some embodiments, the peak of the emission spectrum of the first guest material is less than 600 nm.

[0017] In some embodiments, the first guest material includes at least one luminescent material. In the case where the first guest material includes two luminescent materials, the spacing between the emission spectrum peaks of the two luminescent materials is less than or equal to 30 nm.

[0018] In some embodiments, the peak value of the emission spectrum of the first guest material is in the range of 465 nm to 475 nm, and the peak value of the absorption spectrum of the second guest material of the second green light-emitting layer is in the range of 507 nm to 517 nm.

[0019] In some embodiments, the peak value of the emission spectrum of the first guest material is in the range of 525nm to 535nm, the peak value of the absorption spectrum of the second guest material of the second green light-emitting layer is in the range of 510nm to 520nm, and the peak value of the absorption spectrum of the second guest material of the second red light-emitting layer is in the range of 595nm to 605nm.

[0020] In some embodiments, the first guest material includes at least one luminescent material. In the case where the first guest material includes two luminescent materials, at least one of the two luminescent materials is doped with boron, and the doping ratio of the boron element ranges from 0.5% to 5%.

[0021] In some embodiments, the second guest material of the at least one color of the second light-emitting layer includes at least one light-emitting material. In the case where the second guest material includes two light-emitting materials, the spacing between the emission spectrum peaks of the two light-emitting materials is less than or equal to 30 nm.

[0022] In some embodiments, the second guest material of the second light-emitting layer of at least one color includes at least one light-emitting material; when the second guest material includes two light-emitting materials, at least one of the two light-emitting materials is doped with boron element, and the doping ratio of the boron element is in the range of 0.5% to 5%.

[0023] In some embodiments, the first guest material includes: at least one of a fluorescent material, a phosphorescent material, and a thermally activated delayed fluorescent material; and / or, the second guest material includes: at least one of a fluorescent material, a phosphorescent material, or a thermally activated delayed fluorescent material with multiple resonance characteristics.

[0024] In some embodiments, the first light-emitting layer further includes a first host material, and the first host material includes a single host material or a PN mixed host material.

[0025] In some embodiments, the second light-emitting layer material of at least one color further includes a second host material; and the second host material includes a bipolar host material.

[0026] In some embodiments, the second host material includes a single host material or a PN mixed host material. In the case where the second host material is a PN mixed host material, the N-type material has a thermally activated delayed fluorescence characteristic.

[0027] In some embodiments, the microcavity includes a plurality of sub-microcavities, including a red sub-microcavity corresponding to the second red light-emitting layer, a green sub-microcavity corresponding to the second green light-emitting layer, and a blue sub-microcavity corresponding to the second blue light-emitting layer. The number of film layers located between the anode layer and the cathode layer and corresponding to the sub-microcavity of any color is d, and the optical thickness of the d film layers is L, where L satisfies:

[0028]

[0029] Where d is a positive integer, n m The refractive index of the mth film layer among the d film layers, r m is the thickness of the mth film layer, k is a natural number, λ is the target spectrum peak wavelength, is the phase shift caused by the target light after being reflected from the anode layer.

[0030] In some embodiments, the length of the blue sub-microcavity is smaller than the length of the red sub-microcavity. The length of the blue sub-microcavity is smaller than the length of the green sub-microcavity.

[0031] In some embodiments, the thickness of the first light-emitting layer ranges from 15 nm to 60 nm; and / or the thickness of the second light-emitting layer ranges from 10 nm to 50 nm.

[0032] In some embodiments, the first auxiliary layer includes a light-transmitting conductive layer, a hole injection layer, a first hole transport layer and an electron blocking layer; and / or, the second auxiliary layer includes a first hole blocking layer, a first electron transport layer, a first charge generation layer, a second charge generation layer and a microcavity adjustment layer; and / or, the third auxiliary layer includes: a second hole blocking layer, a second electron transport layer and an electron injection layer.

[0033] In some embodiments, the microcavity adjustment layer includes: a second hole transport layer, a red sub-microcavity adjustment layer disposed between the second hole transport layer and a second red light-emitting layer, a green sub-microcavity adjustment layer disposed between the second hole transport layer and a second green light-emitting layer, and a blue sub-microcavity adjustment layer disposed between the second hole transport layer and a second blue light-emitting layer. The red sub-microcavity adjustment layer and the blue sub-microcavity adjustment layer have different lengths, and the green sub-microcavity adjustment layer and the blue sub-microcavity adjustment layer have different lengths.

[0034] In some embodiments, the red sub-microcavity adjustment layer includes a red hole transport layer and a red electron blocking layer stacked sequentially in a direction away from the backplate, and the green sub-microcavity adjustment layer includes a green hole transport layer and a green electron blocking layer stacked sequentially in a direction away from the backplate. The red hole transport layer and the green hole transport layer are respectively used to adjust the length of the corresponding color sub-microcavity.

[0035] In some embodiments, the thickness of the light-transmitting conductive layer is less than or equal to 10 nm; and / or, the thickness of the hole injection layer is less than or equal to 10 nm; and / or, the thickness of the electron blocking layer is less than or equal to 10 nm; and / or, the thickness of the first hole blocking layer is less than or equal to 10 nm; and / or, the thickness of the first electron transport layer ranges from 15 nm to 50 nm; and / or, the thickness of the first charge generation layer is less than or equal to 10 nm; and / or, the thickness of the second charge generation layer is less than or equal to 10 nm; and / or, the thickness of the second hole blocking layer is less than or equal to 10 nm; and / or, the thickness of the second electron transport layer ranges from 15 nm to 50 nm.

[0036] In some embodiments, there are multiple first light-emitting layers, and the second auxiliary layer is provided between any two adjacent first light-emitting layers; and / or, the multiple second light-emitting layers are located in the same layer and constitute a light-emitting layer group, there are multiple light-emitting layer groups, and the third auxiliary layer is provided between any two adjacent light-emitting layer groups.

[0037] In some embodiments, the second auxiliary layer includes a charge generation layer. The first light-emitting layer can emit at least two different colors of light. The plurality of second light-emitting layers include a plurality of second blue light-emitting layers, a plurality of second red light-emitting layers, and a plurality of second green light-emitting layers.

[0038] In some embodiments, the substrate is a flexible substrate.

[0039] In some embodiments, the anode layer includes: a reflective layer; or, the anode layer includes: a reflective layer, and a light-transmitting layer located on a side of the reflective layer close to the backplane.

[0040] In some embodiments, the thickness of the cathode layer ranges from 10 nm to 20 nm.

[0041] In some embodiments, the display substrate further includes an optical cover layer and / or an encapsulation layer sequentially stacked on the cathode layer.

[0042] In some embodiments, when the display substrate includes an encapsulation layer, a type of the encapsulation layer includes thin film encapsulation.

[0043] In some embodiments, the second red light-emitting layer can emit red light with a wavelength in the range of 615nm to 630nm. The second green light-emitting layer can emit green light with a wavelength in the range of 515nm to 535nm. The second blue light-emitting layer can emit blue light with a wavelength in the range of 460nm to 475nm.

[0044] In another aspect, a display device is provided, comprising: the display substrate according to any one of the embodiments of the above aspect.

[0045] In some embodiments, the display device further comprises a frame, a circuit board, and a data driver integrated circuit. The display substrate is disposed in the frame.

[0046] The above-mentioned display device has the same structure and beneficial technical effects as the display substrate provided in some of the above-mentioned embodiments, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] To more clearly illustrate the technical solutions of the present disclosure, the following briefly introduces the drawings required for use in some embodiments of the present disclosure. Obviously, the drawings described below are only drawings of some embodiments of the present disclosure, and those skilled in the art can also derive other drawings based on these drawings. Furthermore, the drawings described below are schematic diagrams and are not intended to limit the actual dimensions of the products, actual processes of the methods, actual timing of signals, and the like involved in the embodiments of the present disclosure.

[0048] Figure 1 is a structural diagram of a display device according to some embodiments of the present disclosure;

[0049] Figure 2 is a structural diagram of a display substrate according to some embodiments of the present disclosure;

[0050] Figure 3 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0051] Figure 4 A structural diagram showing a substrate in the first embodiment;

[0052] Figure 5 A structural diagram showing a substrate in the second manner;

[0053] Figure 6 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0054] Figure 7 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0055] Figure 8 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0056] Figure 9 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0057] Figure 10 This is a spectrum diagram of part of the light-emitting layer in Verification Example 1;

[0058] Figure 11 This is a spectrum diagram of part of the light-emitting layer in Verification Example 2;

[0059] Figure 12 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0060] Figure 13 2 is a structural diagram of another display substrate according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0061] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the embodiments described are only some embodiments of the present disclosure, not all embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present disclosure.

[0062] Unless the context requires otherwise, throughout the specification and claims, the term "comprise" and its other forms, such as the third person singular form "comprises" and the present participle form "comprising", are to be interpreted as open and inclusive, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" are intended to indicate that the particular features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the particular features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0063] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0064] When describing some embodiments, the term "connected" and its derivatives may be used. For example, when describing some embodiments, the term "connected" may be used to indicate that two or more components are in direct physical or electrical contact with each other. The embodiments disclosed herein are not necessarily limited to the embodiments disclosed herein.

[0065] “At least one of A, B and C” has the same meaning as “at least one of A, B or C” and both include the following combinations of A, B and C: A only, B only, C only, the combination of A and B, the combination of A and C, the combination of B and C, and the combination of A, B and C.

[0066] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0067] The use of "configured to" herein is intended to be open and inclusive language that does not exclude devices adapted or configured to perform additional tasks or steps.

[0068] Additionally, the use of “based on” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” one or more stated conditions or values ​​may, in practice, be based on additional conditions or values ​​beyond those stated.

[0069] As used herein, "about" includes the stated value and the average value that is within an acceptable range of deviation from the particular value, as determined by one of ordinary skill in the art taking into account the measurements in question and errors associated with measurement of the particular quantity (i.e., limitations of the measurement system).

[0070] It will be understood that when a layer or element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present therebetween.

[0071] Exemplary embodiments are described herein with reference to cross-sectional and / or plan views that are idealized exemplary drawings. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are contemplated. Therefore, the exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include deviations in shape due to, for example, manufacturing. For example, an etched region shown as a rectangle will typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of regions of the device and are not intended to limit the scope of the exemplary embodiments.

[0072] Some embodiments of the present disclosure provide a display substrate and a display device. The display substrate 100 and the display device 1000 are respectively introduced below with reference to the accompanying drawings.

[0073] like Figure 1 As shown, some embodiments of the present disclosure provide a display device 1000. The display device 1000 can be any device that displays images, whether in motion (e.g., video) or stationary (e.g., still images), and whether textual or electronic. More specifically, it is contemplated that the embodiments described may be implemented in or associated with a variety of electronic devices, such as (but not limited to) mobile phones, wireless devices, personal data assistants (PDAs), handheld or portable computers, GPS receivers / navigators, cameras, MP4 video players, video cameras, game consoles, watches, clocks, calculators, television monitors, flat-panel displays, computer monitors, automotive displays (e.g., speedometer displays, etc.), navigation systems, cockpit controls and / or displays, displays of camera views (e.g., displays of rearview cameras in vehicles), electronic photographs, electronic billboards or signs, projectors, architectural structures, packaging, and aesthetic structures (e.g., displays of images of a piece of jewelry), etc.

[0074] In some examples, the display device 1000 includes a frame, a display substrate 100 disposed in the frame, a circuit board, a data driver IC (Integrated Circuit), and other electronic components.

[0075] The above-mentioned display substrate 100 can be, for example, an organic light emitting diode display substrate, a quantum dot light emitting diode (QLED) display substrate, a micro light emitting diode (Micro LED) display substrate or a mini light emitting diode (Mini LED) display substrate, etc., and the present disclosure does not make any specific limitations on this.

[0076] In the following, some embodiments of the present disclosure are schematically described by taking the display substrate 100 as an OLED display substrate as an example.

[0077] In some embodiments, as Figure 2 As shown, the display substrate 100 includes: a back plate 1 .

[0078] In some examples, the backplane 1 includes a substrate 11 and a plurality of pixel driving circuits 12 disposed on the substrate 11 .

[0079] There are many types of the substrate 11, which can be selected according to actual needs.

[0080] For example, the substrate 11 may be a rigid substrate, the material of which may include glass, quartz, or plastic.

[0081] For example, the substrate 11 may be a flexible substrate. The material of the flexible substrate may include PET (Polyethylene terephthalate), PEN (Polyethylenenaphthalate two formic acid glycol ester), or PI (Polyimide).

[0082] In some examples, the plurality of pixel driving circuits 12 are arranged in an array, for example. The pixel driving circuit 12 includes a plurality of transistors and at least one storage capacitor.

[0083] The pixel driving circuit 12 may have various structures, which can be selected based on actual needs. For example, the pixel driving circuit 12 may have a structure such as "3T1C," "4T1C," "6T1C," "7T1C," "6T2C," "7T2C," or "8T2C." "T" represents a transistor, and the number preceding "T" represents the number of transistors. "C" represents a storage capacitor, and the number preceding "C" represents the number of storage capacitors.

[0084] For example, Figure 3 The pixel driving circuit 12 is represented by a transistor 121 .

[0085] In some embodiments, as Figure 3 As shown, the display substrate 100 further includes: a light emitting device layer 2 .

[0086] In some examples, such as Figure 3 As shown, the light emitting device layer 2 includes a plurality of light emitting devices 2a, such as Figure 2 As shown, the plurality of light emitting devices 2a are arranged in an array, for example, wherein the light emitting devices 2a are, for example, OLEDs.

[0087] The pixel driving circuit 12 is electrically connected to the light emitting device 2a. There are many types of electrical connection relationships between the two, which can be selected and set according to actual needs, and this disclosure does not limit this.

[0088] For example, the pixel driving circuit 12 and the light emitting device 2a may be electrically connected in a one-to-one correspondence. For another example, one pixel driving circuit 12 may be electrically connected to multiple light emitting devices 2a. For another example, multiple pixel driving circuits 12 may be electrically connected to one light emitting device 2a.

[0089] The structure of the display substrate 100 is schematically described below by taking the example that the pixel driving circuit 12 and the light emitting device 2 a can be electrically connected in a one-to-one correspondence.

[0090] It is understood that the pixel driving circuit 12 can generate a driving signal and transmit the driving signal to the corresponding light-emitting device 2a to control the light-emitting state of the light-emitting device 2a. The light-emitting state includes, for example, whether the light-emitting device 2a is emitting light or the brightness of the light-emitting device 2a. Multiple pixel driving circuits 12 jointly control the light-emitting state of the above-mentioned multiple light-emitting devices 2a, thereby enabling the display substrate 100 to display an image.

[0091] Here, each pixel driving circuit 12 and the light emitting device 2a electrically connected thereto may be referred to as a sub-pixel.

[0092] It should be noted that there are two main ways for the display substrate to achieve full-color display. For example, one way is to provide a full-color display solution through R / G / B separate light-emitting units, and the other way is to provide a full-color solution through color conversion or color filtering.

[0093] In one implementation, providing a full-color display solution through R / G / B separate light-emitting units means that the light-emitting device mainly includes an anode, a light-emitting layer, and a cathode stacked in sequence in a direction away from the substrate. The light-emitting layer can be a red light-emitting layer, a green light-emitting layer, or a blue light-emitting layer, and accordingly, the light-emitting device can be a red light-emitting device, a green light-emitting device, or a blue light-emitting device. The red light-emitting device can emit red light under the control of the corresponding pixel driving circuit, the green light-emitting device can emit green light under the control of the corresponding pixel driving circuit, and the blue light-emitting device can emit blue light under the control of the corresponding pixel driving circuit. Multiple light-emitting devices cooperate to achieve full-color display. However, in this solution, the luminous efficiency and luminous brightness of the light-emitting device are low.

[0094] In another implementation, there are two main ways to provide a full-color solution through color conversion or color filtering.

[0095] like Figure 4 As shown, in the first embodiment, light-emitting device 2a' is a series-connected bottom-emitting light-emitting device that emits white light. The display substrate also includes a color filter CF disposed on the side of substrate 11' away from light-emitting device 2a'. The white light emitted by light-emitting device 2a' is converted into red, green, or blue light after passing through color filter CF, thereby achieving full-color display. However, the structure of bottom-emitting light-emitting devices makes it difficult to improve brightness at normal viewing angles. Furthermore, using top-emitting light-emitting devices increases process complexity and results in excessive light loss in certain wavelengths.

[0096] like Figure 5 As shown, in the second embodiment, light-emitting device 2a' is a tandem top-emitting light-emitting device configured to emit blue light. The display substrate further includes a red quantum dot conversion layer R-CC and a green quantum dot conversion layer G-CC, disposed on the side of light-emitting device 2a' facing away from substrate 11'. Blue light passing through the red quantum dot conversion layer R-CC is converted to red light, while blue light passing through the green quantum dot conversion layer G-CC is converted to green light, thereby achieving full-color display. However, due to the light conversion efficiencies of the red and green quantum dot conversion layers R-CC and G-CC, the color purity of the converted red and green light is low. Therefore, corresponding color filters are required. For example, a red filter R-CF is disposed on the side of the red quantum dot conversion layer R-CC facing away from substrate 11', and a green filter G-CF is disposed on the side of the green quantum dot conversion layer G-CC facing away from substrate 11', to improve color purity. This increases the process complexity and power consumption of the display substrate.

[0097] Based on this, Figure 3As shown, in some embodiments of the present disclosure, the light-emitting device layer 2 includes an anode layer 21, a first auxiliary layer 22, a first light-emitting layer 23, a second auxiliary layer 24, multiple second light-emitting layers 25, a third auxiliary layer 26 and a cathode layer 27 arranged on the backplane 1.

[0098] In some examples, such as Figure 3 As shown, the anode layer 21 includes a plurality of anodes 211, which are arranged in an array, for example. Each anode 211 corresponds to a light-emitting device 2a. Each light-emitting device 2a is electrically connected to a corresponding pixel driving circuit 12, for example, via the anode 211. The anode 211 can receive a driving signal from the corresponding pixel driving circuit 12 and cooperate with the corresponding pixel driving circuit 12 to achieve individual control of the light-emitting device 2a.

[0099] For example, the material of the anode layer 21 includes a conductive material with a relatively high work function. The structure of the anode layer 21 can be, for example, a single-layer structure, or a structure in which multiple layers are stacked in sequence.

[0100] Exemplarily, when the anode layer 21 is a single-layer structure, the anode layer 21 includes a reflective layer. The single-layer structure (eg, the reflective layer) has good light reflection performance and can reflect light incident on the anode layer 21 .

[0101] Exemplarily, when the structure of the anode layer 21 is a structure in which multiple film layers are stacked in sequence, the anode layer 21 includes a reflective layer and a light-transmitting layer located on the side of the reflective layer close to the backplane 1. The film layer in the multi-layer film layer that is far from the backplane 1 is a film layer with good light reflective performance (such as a reflective layer), which can reflect light incident on the anode layer 21. The material of the film layer with good light reflective performance can, for example, include at least one of Al (aluminum), Ag (silver), or Mg (magnesium). The film layer in the multi-layer film layer that is close to the backplane 1 can, for example, be a film layer with good light transmittance (such as a light-transmitting layer). The material of the film layer with good light transmittance can, for example, include ITO (Indium Tin Oxide, indium tin oxide), IZO (Indium Zinc Oxide, indium zinc oxide), etc.

[0102] Exemplarily, the method for forming the anode 211 includes: forming (for example, by using a sputtering process) a layer of conductive film (the conductive film is a single-layer structure or a structure in which multiple films are stacked in sequence) on the back plate 1, and then patterning the conductive film (for example, by using a photolithography process to etch the conductive film) to obtain multiple independent anodes 211.

[0103] It should be noted that the display substrate 100 may further include a pixel defining layer disposed on the side of the anode layer 21 away from the substrate 11. The pixel defining layer has a plurality of openings, each corresponding to the plurality of anodes 211. Each opening exposes a portion of a corresponding anode 211, so that the anode 211 contacts the film layer on the side away from the substrate 11, thereby forming an electrical connection.

[0104] In some examples, such as Figure 3 As shown, the first auxiliary layer 22 is disposed on a side of the anode layer 21 away from the substrate 11. Optionally, the first auxiliary layer 22 is located on a side of the pixel defining layer away from the substrate 11.

[0105] For example, the first auxiliary layer 22 may contact the anode 211 through the opening of the pixel defining layer to form an electrical connection.

[0106] Exemplarily, the first auxiliary layer 22 includes a number of film layers stacked in sequence, where a is a positive integer. For example, the number of film layers included in the first auxiliary layer 22 is one, two, three, or four.

[0107] Optionally, when the first auxiliary layer 22 includes one film layer, the first auxiliary layer 22 covers the anode layer 21. That is, different light-emitting devices 2a share the first auxiliary layer 22.

[0108] Optionally, when the first auxiliary layer 22 includes at least two film layers, at least one film layer covers the anode layer 21. That is, different light-emitting devices 2a share the at least one film layer.

[0109] For example, the present disclosure may form the first auxiliary layer 22 by using an evaporation process.

[0110] By making different light-emitting devices 2 a share the film layer of the first auxiliary layer 22 , patterning of the first auxiliary layer 22 can be avoided, which is beneficial for simplifying the preparation process of the first auxiliary layer 22 and the display substrate 100 .

[0111] In some examples, such as Figure 3 As shown, the first light-emitting layer 23 is disposed on a side of the first auxiliary layer 22 away from the substrate 11 .

[0112] Exemplarily, the first light-emitting layer 23 is provided as a whole layer, and different light-emitting devices 2 a share the first light-emitting layer 23 .

[0113] It should be noted that the first auxiliary layer 22 is located between the anode layer 21 and the first light-emitting layer 23. The first auxiliary layer 22 is mainly used to improve the hole mobility and reduce the hole injection barrier to increase the amount of holes migrating to the first light-emitting layer 23, increase the recombination rate of holes and electrons migrating to the first light-emitting layer 23, and improve the luminous efficiency of the first light-emitting layer 23.

[0114] In some examples, such as Figure 3 As shown, the second auxiliary layer 24 is disposed on the side of the first light emitting layer 23 away from the substrate 11. That is, the plurality of first light emitting layers 23 are disposed between the first auxiliary layer 22 and the second auxiliary layer 24. The second auxiliary layer 24 and the first light emitting layer 23 are in contact with each other to form an electrical connection.

[0115] Exemplarily, the second auxiliary layer 24 includes b film layers stacked in sequence, where b is a positive integer. For example, the number of film layers included in the second auxiliary layer 24 is one, two, three, or four.

[0116] Exemplarily, different light-emitting devices 2 a share the second auxiliary layer 24 .

[0117] For example, the present disclosure may form the second auxiliary layer 24 by using an evaporation process.

[0118] By making different light-emitting devices 2 a share the film layer of the second auxiliary layer 24 , patterning of the second auxiliary layer 24 can be avoided, which is beneficial for simplifying the preparation process of the second auxiliary layer 24 and the display substrate 100 .

[0119] In some examples, such as Figure 3 As shown, the plurality of second light-emitting layers 25 are disposed on a side of the second auxiliary layer 24 away from the substrate 11. For example, the plurality of second light-emitting layers 25 are located on the same layer, and each second light-emitting layer 25 is in contact with the second auxiliary layer 24 to form an electrical connection. Of course, at least two second light-emitting layers 25 may also be stacked. This disclosure uses the example of the plurality of second light-emitting layers 25 being located on the same layer.

[0120] Exemplarily, the plurality of second light-emitting layers 25 have at least two different colors.

[0121] For example, the plurality of second light-emitting layers 25 may have two different colors. Alternatively, the plurality of second light-emitting layers 25 may include a plurality of second blue light-emitting layers 25B and a plurality of second red light-emitting layers 25R. Alternatively, the plurality of second light-emitting layers 25 may include a plurality of second blue light-emitting layers 25B and a plurality of second green light-emitting layers 25G. Alternatively, the plurality of second light-emitting layers 25 may include a plurality of second red light-emitting layers 25R and a plurality of second green light-emitting layers 25G. The second red light-emitting layers 25R may emit red light, the second green light-emitting layers 25G may emit green light, and the second blue light-emitting layers 25B may emit blue light.

[0122] For another example, the plurality of second light-emitting layers 25 have three different colors. Optionally, the plurality of second light-emitting layers 25 include a plurality of second blue light-emitting layers 25B, a plurality of second red light-emitting layers 25R, and a plurality of second green light-emitting layers 25G.

[0123] Because the plurality of second light-emitting layers 25 have two different colors, they need to be prepared and formed in different processes, wherein each color of the second light-emitting layer 25 can be formed in one process. For example, if the plurality of second light-emitting layers 25 are formed using an evaporation process, the second light-emitting layers 25 of one color can be formed in one process, and then the second light-emitting layers 25 of the other color can be formed in another process.

[0124] It should be noted that the second auxiliary layer 24 is located between the multiple first light-emitting layers 23 and the multiple second light-emitting layers 25. The second auxiliary layer 24 is mainly used to connect the first light-emitting layers 23 and the second light-emitting layers 25 in series to form a series light-emitting device.

[0125] In some examples, such as Figure 3 As shown, the third auxiliary layer 26 is disposed on a side of the plurality of second light-emitting layers 25 away from the substrate 11. That is, the plurality of second light-emitting layers 25 are disposed between the second auxiliary layer 24 and the third auxiliary layer 26. The third auxiliary layer 26 contacts each second light-emitting layer 25 to form an electrical connection.

[0126] Exemplarily, the third auxiliary layer 26 includes c film layers stacked in sequence, where c is a positive integer. For example, the number of film layers included in the third auxiliary layer 26 is one, two, or three.

[0127] Optionally, different light-emitting devices 2 a share the third auxiliary layer 26 .

[0128] For example, the present disclosure may form the third auxiliary layer 26 by using an evaporation process.

[0129] By making different light-emitting devices 2 a share the third auxiliary layer 26 , patterning of the third auxiliary layer 26 can be avoided, which is beneficial for simplifying the preparation process of the third auxiliary layer 26 and the display substrate 100 .

[0130] In some examples, such as Figure 3 As shown, the cathode layer 27 is disposed on a side of the third auxiliary layer 26 away from the substrate 11 and contacts the third auxiliary layer 26 to form an electrical connection.

[0131] Exemplarily, different light-emitting devices 2a share the cathode layer 27. That is, the cathode layer 27 is a whole layer structure.

[0132] For example, the present disclosure may form the cathode layer 27 using an evaporation process.

[0133] By making different light-emitting devices 2 a share the cathode layer 27 , patterning of the cathode layer 27 can be avoided, which is beneficial for simplifying the preparation process of the cathode layer 27 and the display substrate 100 .

[0134] It should be noted that the above-mentioned third auxiliary layer 26 is located between multiple second light-emitting layers 25 and the cathode layer 27. The third auxiliary layer 26 is mainly used to improve the electron mobility, so as to increase the amount of holes migrating to the first light-emitting layer 23, increase the recombination rate of holes and electrons migrating to the first light-emitting layer 23, and avoid the leakage of holes or excitons formed by the recombination of holes and electrons from the second light-emitting layer 25, thereby improving the luminous efficiency of the first light-emitting layer 23.

[0135] In some examples, anode layer 21 has a high reflectivity, and cathode layer 27 is a transflective film layer. "Transflective" refers to the ability of cathode layer 27 to both transmit and reflect light, without specifying specific transmittance and reflectance. This means that light-emitting device 2a in the disclosed embodiments is a top-emitting device.

[0136] Exemplarily, the reflectivity of the anode layer 21 is greater than or equal to 80%.

[0137] For example, the thickness of the cathode layer 27 is in the range of 10 nm to 20 nm, which can enhance the light transmittance of the cathode layer 27 while ensuring the conductivity of the cathode layer 27 , thereby improving the luminous efficiency of the display substrate 100 .

[0138] For example, the thickness of the cathode layer 27 can be 10 nm, 12 nm, 14 nm, 17 nm, or 20 nm.

[0139] Exemplarily, the transmittance of the cathode layer 27 to light with a wavelength of 530 nm ranges from 45% to 60%.

[0140] For example, the transmittance may be 45%, 50%, 53%, 57% or 60%.

[0141] It is understandable that if Figure 6 As shown, based on the properties of anode layer 21 and cathode layer 27, a microcavity A can be formed between anode layer 21 and cathode layer 27. In this way, light emitted by first light-emitting layer 23 and second light-emitting layer 25 can reflect and interfere within microcavity A, generating a microcavity effect. This enhances the luminous intensity of the emitted light, narrows the spectrum of the emitted light, and improves the luminous efficiency of light-emitting device 2a. For example, the luminous intensity of blue light can be enhanced and the spectrum of blue light can be narrowed.

[0142] In some examples, the optical thickness of the a film layers included in the first auxiliary layer 22 is L1, and L1 satisfies:

[0143]

[0144] Among them, n his the refractive index of the hth film layer among the a films, r h is the thickness of the hth film layer mentioned above.

[0145] The optical thickness of the b layers included in the second auxiliary layer 24 is L2, and L2 satisfies:

[0146]

[0147] Among them, n i is the refractive index of the i-th film layer among the b film layers mentioned above, r i is the thickness of the i-th film layer mentioned above.

[0148] The optical thickness of the c layers included in the third auxiliary layer 26 is L3, and L3 satisfies:

[0149]

[0150] n j is the refractive index of the jth film layer among the c film layers mentioned above, r j is the thickness of the j-th film layer mentioned above.

[0151] L1, L2, L3 satisfy the formula:

[0152] |L1-L3|≤30nm.

[0153] For example, The value of can be, for example, 0.7, 0.83, 0.9, 1.1 or 1.3.

[0154] Through the above-mentioned configuration, the color purity of the light emitted by the light-emitting device 2a in the display substrate 100 can be improved. Therefore, the display substrate 100 of the present disclosure can reduce the number of filters, thereby reducing the filter's obstruction of the light emitted by the light-emitting device 2a, and improving the luminous efficiency of the display substrate 100 of the present disclosure. Furthermore, the present disclosure can achieve the same brightness as the first and second implementations described above while reducing the driving voltage of the pixel driving circuit 12 in the display substrate 100, thereby reducing the power consumption of the display substrate 100 and increasing the luminous life of the light-emitting device 2a.

[0155] It should be noted that the refractive index range of the hth film layer, the ith film layer, and the jth film layer for light with a wavelength of 460 nm is all 1.7 to 2.0.

[0156] Illustratively, the refractive indices of the hth film layer, the ith film layer, and the jth film layer for light with a wavelength of 460 nm may be the same or different.

[0157] For example, the refractive indices of the hth film layer, the ith film layer, and the jth film layer for light with a wavelength of 460 nm are: 1.7, 1.75, 1.8, 1.9, and 2.0.

[0158] In some embodiments, as Figure 3 As shown, the second light emitting layers 25 include: a plurality of second blue light emitting layers 25B, a plurality of second red light emitting layers 25R, and a plurality of second green light emitting layers 25G. The wavelength of light emitted by the first light emitting layer 23 is smaller than the wavelength of light emitted by the second light emitting layer 25 of at least one color.

[0159] For example, the wavelength of light emitted by the first light-emitting layer 23 is shorter than the wavelength of light emitted by the second blue light-emitting layer 25B; alternatively, the wavelength of light emitted by the first light-emitting layer 23 is shorter than the wavelength of light emitted by the second red light-emitting layer 25R; alternatively, the wavelength of light emitted by the first light-emitting layer 23 is shorter than the wavelength of light emitted by the second green light-emitting layer 25G. Alternatively, the wavelength of light emitted by the first light-emitting layer 23 is shorter than the wavelength of light emitted by the second red light-emitting layer 25R, and shorter than the wavelength of light emitted by the second green light-emitting layer 25G, although this disclosure is not limited thereto.

[0160] For example, the first light emitting layer 23 can emit blue light or yellow light.

[0161] By making the wavelength of the light emitted by the first light-emitting layer 23 shorter than the wavelength of the light emitted by the second light-emitting layer 25 of at least one color, the light emitted by the first light-emitting layer 23 can be emitted to the plurality of second light-emitting layers 25 to excite at least one of the second red light-emitting layer 25R, the second green light-emitting layer 25G, and the second blue light-emitting layer 25B to emit light of the corresponding color, thereby increasing the luminance and luminous efficiency of the display substrate 100. Figure 5 As shown, the light emitted by the first light-emitting layer 23 can also be reflected multiple times in the microcavity A, so that the light emitted by the first light-emitting layer 23 can be emitted to the above-mentioned multiple second light-emitting layers 25 multiple times, further increasing the excitation effect of the light emitted by the first light-emitting layer 23 on at least one of the multiple second light-emitting layers 25, and further increasing the luminous brightness and luminous efficiency of the display substrate 100.

[0162] It should be noted that, when the plurality of second light-emitting layers 25 include: a plurality of second blue light-emitting layers 25B, a plurality of second red light-emitting layers 25R and a plurality of second green light-emitting layers 25G, the above n h is the refractive index of the hth film layer among the a film layers for the central wavelength of red light, green light or blue light, and the n i is the refractive index of the i-th film layer among the b film layers for the central wavelength of red light, green light or blue light.

[0163] Illustratively, the wavelength range of red light is 615 nm to 630 nm, the wavelength range of green light is 515 nm to 535 nm, and the wavelength range of blue light is 460 nm to 475 nm.

[0164] In some embodiments, the first light-emitting layer 23 includes a first guest material and the second light-emitting layer 25 includes a second guest material. The emission spectrum of the first guest material at least partially overlaps with the absorption spectrum of the second guest material of the second light-emitting layer 25 of at least one color.

[0165] It should be noted that the materials for the first and second light-emitting layers 23 and 25 include a host material and a guest material doped within the host material. The host material itself has excellent film-forming properties and can be mixed with other materials exhibiting excellent light-emitting properties. The guest material itself exhibits excellent light-emitting properties. Therefore, when the host material and the guest material doped therein are used to form the first or second light-emitting layer 23 or 25, the host material includes molecules in highly excited energy states, and these molecules can transfer their energy to the guest material. This can alter the wavelength of light emitted by the first or second light-emitting layer 23 or 25, thereby improving the light-emitting efficiency of the first or second light-emitting layer 23 or 25.

[0166] Illustratively, the first guest material is a material mainly used for emitting light in the first light-emitting layer 23 , and the second guest material is a material mainly used for emitting light in the second light-emitting layer 25 .

[0167] The above-mentioned “at least partially overlap” means that the emission spectrum of the first guest material partially overlaps with the absorption spectrum of the second guest material of the second light-emitting layer 25 of at least one color, or the emission spectrum of the first guest material completely overlaps with the absorption spectrum of the second guest material of the second light-emitting layer 25 of at least one color.

[0168] Illustratively, the emission spectrum of the first guest material in the first light-emitting layer 23 at least partially overlaps with the absorption spectrum of the second guest material in the second red light-emitting layer 25R; or, the emission spectrum of the first guest material in the first light-emitting layer 23 at least partially overlaps with the absorption spectrum of the second guest material in the second green light-emitting layer 25G. Alternatively, the emission spectrum of the first guest material in the first light-emitting layer 23 at least partially overlaps with the absorption spectrum of the second guest material in the second blue light-emitting layer 25B; or, the emission spectrum of the first guest material in the first light-emitting layer 23 at least partially overlaps not only with the absorption spectrum of the second guest material in the second red light-emitting layer 25R, but also with the absorption spectrum of the second guest material in the second green light-emitting layer 25G. This disclosure is not limited to this.

[0169] By at least partially overlapping the emission spectrum of the first guest material in the first light-emitting layer 23 with the absorption spectrum of the second guest material in the at least one color second light-emitting layer 25, a portion of the light emitted by the first guest material in the first light-emitting layer 23 can be absorbed by the second guest material in the at least one color second light-emitting layer 25. Consequently, the second guest material in the at least one color second light-emitting layer 25 emits light under the excitation of the light emitted by the first guest material, thereby improving the luminous efficiency of the second guest material in the second light-emitting layer 25. Furthermore, another portion of the light emitted by the first guest material in the first light-emitting layer 23 can be emitted through the cathode layer 27 and form a tandem light-emitting device with the light emitted by the second light-emitting layer 25, thereby enhancing the luminous brightness of the display substrate 100.

[0170] It should be noted that when light emitted by the first light-emitting layer 23 in the display substrate 100 is directed toward the second light-emitting layer 25, the second light-emitting layer 25 absorbs the light emitted by the first light-emitting layer 23 and excites it to emit light of a corresponding color. Furthermore, the first light-emitting layer 23 and the second light-emitting layer 25 themselves can form a tandem light-emitting assembly. The combined effect of these two light-emitting mechanisms allows the display substrate 100 to achieve higher light-emitting efficiency.

[0171] It can be understood that the more the emission spectrum of the first guest material overlaps with the absorption spectrum of the second guest material in the second light-emitting layer 25, the light emitted by the first guest material can excite the second guest material to emit more light, and the luminous efficiency of the second guest material in the second light-emitting layer 25 is higher.

[0172] In some embodiments, the overlap between the emission spectrum of the first guest material in the first light-emitting layer 23 and the absorption spectrum of the second guest material in the second light-emitting layer 25 is greater than or equal to 60% of the wavelength range of the emission spectrum of the first guest material.

[0173] For example, the overlap between the emission spectrum of the first guest material and the absorption spectrum of the second guest material may be 60%, 70%, 80%, 90% or 99% of the wavelength range of the emission spectrum of the first guest material.

[0174] With this arrangement, greater than or equal to 60% of all light emitted by the first guest material can be absorbed by the second guest material, thereby improving the utilization rate of the light emitted by the first guest material by the second guest material.

[0175] In some embodiments, the overlap between the emission spectrum of the first guest material in the first light-emitting layer 23 and the absorption spectrum of the second guest material in the second light-emitting layer 25 is greater than or equal to 60% of the wavelength range of the absorption spectrum of the second guest material.

[0176] For example, the overlap between the emission spectrum of the first guest material and the absorption spectrum of the second guest material may be 60%, 70%, 80%, 90% or 99% of the wavelength range of the absorption spectrum of the second guest material.

[0177] This arrangement allows more light emitted by the first guest material to be absorbed by the second guest material, thereby improving the utilization rate of the light emitted by the first guest material by the second guest material.

[0178] In some embodiments, the peak of the emission spectrum of the first guest material of the first light-emitting layer 23 is less than 600 nm.

[0179] For example, the peak of the emission spectrum of the first guest material of the first light-emitting layer 23 may be 465 nm, 500 nm, 515 nm, 560 nm, or 595 nm.

[0180] As mentioned above, the shorter the wavelength of light, the higher the energy of the light. Through the above configuration, it can be ensured that the light emitted by the first light-emitting layer 23 has higher energy, thereby better exciting the second guest material in the second light-emitting layer 25 to emit light.

[0181] In some embodiments, the first guest material of the first light-emitting layer 23 includes at least one light-emitting material. When the first guest material includes two light-emitting materials, the distance between the emission spectrum peaks of the two light-emitting materials is less than or equal to 30 nm.

[0182] For example, the types of the light-emitting materials included in the first guest material may be one or two, etc., which is not limited in the present disclosure.

[0183] It can be understood that different luminescent materials can emit light of different colors. When the first guest material of the first luminescent layer 23 includes one luminescent material, the first luminescent layer 23 can emit light of one color; when the first guest material of the first luminescent layer 23 includes two luminescent materials, the first luminescent layer 23 can emit light of two colors.

[0184] For example, when the first guest material of the first light-emitting layer 23 includes two light-emitting materials, the distance between the emission spectrum peaks of the two light-emitting materials may be 1 nm, 10 nm, 19 nm, 25 nm or 30 nm.

[0185] By making the distance between the emission spectrum peaks of the two luminescent materials of the first guest material less than or equal to 30 nm, the colors of the light emitted by the two luminescent materials of the first guest material can be made closer, thereby improving the color purity of the light emitted by the first luminescent layer 23.

[0186] In some embodiments, the emission spectrum of the first guest material of the first light-emitting layer 23 overlaps with the absorption spectrum of the second guest material of the second green light-emitting layer 25G.

[0187] Illustratively, the light emitted by the first guest material is blue light.

[0188] Illustratively, the peak value of the emission spectrum of the first guest material is in the range of 465 nm to 475 nm, and the peak value of the absorption spectrum of the second guest material of the second green light-emitting layer 25G is in the range of 507 nm to 517 nm.

[0189] For example, the peak emission spectrum of the first guest material may be 465 nm, 467 nm, 469 nm, 471 nm, or 475 nm, etc. The peak absorption spectrum of the second guest material of the second green light emitting layer 25G may be 507 nm, 509 nm, 512 nm, 514 nm, or 517 nm, etc.

[0190] This configuration can make the emission spectrum of the first guest material and the absorption spectrum of the second guest material have a larger overlapping range, thereby improving the luminous efficiency of the second guest material in the second light-emitting layer 25 .

[0191] In some embodiments, the emission spectrum of the first guest material of the first light-emitting layer 23 and the absorption spectra of the second guest material of the two-color second light-emitting layer 25 overlap.

[0192] Illustratively, the light emitted by the first guest material is green light.

[0193] Illustratively, the peak value of the emission spectrum of the first guest material is in the range of 525nm to 535nm, the peak value of the absorption spectrum of the second guest material of the second green light-emitting layer 25G is in the range of 510nm to 520nm, and the peak value of the absorption spectrum of the second guest material of the second red light-emitting layer 25R is in the range of 595nm to 605nm.

[0194] For example, the peak emission spectrum of the first guest material may be 525 nm, 527 nm, 529 nm, 531 nm, or 535 nm. The peak absorption spectrum of the second guest material of the second green light-emitting layer 25G may be 510 nm, 514 nm, 516 nm, 518 nm, or 520 nm. The peak absorption spectrum of the second guest material of the second red light-emitting layer 25R may be 595 nm, 597 nm, 600 nm, 602 nm, or 605 nm.

[0195] This configuration can make the emission spectrum of the first guest material in the first light-emitting layer 23 and the absorption spectrum of the second guest material in the second light-emitting layers 25 have a larger overlap range, thereby improving the luminescence efficiency of the second guest material in the second light-emitting layer 25.

[0196] In some embodiments, when the first guest material of the first light-emitting layer 23 includes two light-emitting materials, at least one of the two light-emitting materials is doped with boron, and the doping ratio of the boron element ranges from 0.5% to 5%.

[0197] For example, the doping ratio of boron element can be: 0.5%, 1.5%, 3.5%, 4% or 5%, etc.

[0198] In some embodiments, the first guest material of the first light-emitting layer 23 includes at least one of a fluorescent material, a phosphorescent material, and a thermally activated delayed fluorescent material.

[0199] Exemplary fluorescent materials include pyrene, condensed carbazole, and boron-containing materials. Phosphorescent materials include iridium (Ir) and platinum (Pt) complexes. Thermally activated delayed fluorescent materials generally have a DA structure, and the S1-T1 ratio of the thermally activated delayed fluorescent material is less than 0.3 eV, where S1 represents the energy level of the material's singlet excited state and T1 represents the energy level of the material's triplet excited state.

[0200] In some embodiments, the first light-emitting layer 23 further includes a first host material. The first host material of the first light-emitting layer 23 is a single host material or a PN mixed host material.

[0201] Exemplarily, the first host material includes at least one of anthracene-based material, fluorene-based material, pyrene-based material, and carbazole-based derivative material. In some embodiments, the thickness of the first light-emitting layer 23 ranges from 15 nm to 60 nm.

[0202] For example, the thickness of the first light emitting layer 23 may be 15 nm, 20 nm, 35 nm, 45 nm, or 60 nm.

[0203] In some embodiments, the second guest material of the at least one color second light emitting layer 25 includes at least one light emitting material. In the case where the second guest material includes two light emitting materials, the spacing between the emission spectrum peaks of the two light emitting materials is less than or equal to 30 nm.

[0204] Alternatively, the second red light-emitting layer may include at least one light-emitting material, or the second green light-emitting layer may include at least one light-emitting material, or the second blue light-emitting layer may include at least one light-emitting material. Alternatively, both the second red light-emitting layer and the second green light-emitting layer may include at least one light-emitting material.

[0205] For example, the type of the light-emitting material included in the second guest material may be one or two, etc. This disclosure does not limit this.

[0206] It can be understood that different luminescent materials can emit light of different colors. When the second guest material of the second luminescent layer 25 includes one luminescent material, the second luminescent layer 25 can emit light of one color; when the second guest material of the second luminescent layer 25 includes two luminescent materials, the second luminescent layer 25 can emit light of two colors.

[0207] For example, when the second guest material of the second light-emitting layer 25 includes two light-emitting materials, the emission spectrum of one of the two light-emitting materials overlaps with the absorption spectrum of the other light-emitting material. This arrangement can increase the luminous efficiency of the two light-emitting materials.

[0208] For example, when the second guest material of the second light-emitting layer 25 includes two light-emitting materials, the distance between the emission spectrum peaks of the two light-emitting materials can be 1 nm, 10 nm, 19 nm, 25 nm or 30 nm.

[0209] By making the distance between the emission spectrum peaks of the two luminescent materials in the second guest material of the second luminescent layer 25 less than or equal to 30 nm, the colors of the light emitted by the two luminescent materials in the second guest material can be made closer, thereby improving the color purity of the light emitted by the second luminescent layer 25.

[0210] In some embodiments, when the second guest material of the second light-emitting layer 25 of at least one color includes two light-emitting materials, at least one of the two light-emitting materials is doped with boron, and the doping ratio of the boron element ranges from 0.5% to 5%.

[0211] For example, the doping ratio of boron element can be: 0.5%, 1.5%, 3.5%, 4% or 5%, etc.

[0212] In some embodiments, the second guest material includes at least one of a fluorescent material, a phosphorescent material, and a thermally activated delayed fluorescent material having multiple resonance characteristics.

[0213] In some embodiments, the second light-emitting layer 25 of at least one color further includes a second host material, wherein the second host material includes a bipolar host material.

[0214] In some embodiments, the second host material is a single host material or a PN mixed host material.

[0215] In some examples, when the second host material is a PN mixed host material, the N-type component has a thermally activated delayed fluorescence characteristic.

[0216] It should be noted that, when the N-type component has thermally activated delayed fluorescence characteristics, the luminous efficiency of the second guest material in the second light-emitting layer 25 can be improved.

[0217] In some embodiments, the second light emitting layer 25 has a thickness ranging from 10 nm to 50 nm.

[0218] For example, the thickness of the second light emitting layer 25 can be 10 nm, 20 nm, 28 nm, 38 nm, or 50 nm.

[0219] In some embodiments, as Figure 6 As shown, microcavity A includes multiple sub-microcavities A1, including a red sub-microcavity A1-R corresponding to the second red light-emitting layer 25R, a green sub-microcavity A1-G corresponding to the second green light-emitting layer 25G, and a blue sub-microcavity A1-B corresponding to the second blue light-emitting layer 25B. The number of film layers located between the anode layer 21 and the cathode layer 27 and corresponding to any color sub-microcavity A1 is d, and the optical thickness of the d film layers is L, where L satisfies:

[0220]

[0221] Where d is a positive integer, n m is the refractive index of the mth film layer among the d film layers mentioned above, r m is the thickness of the mth film layer, k is a natural number, λ is the target spectrum peak wavelength, is the phase shift caused by the target light reflected from the anode layer 21.

[0222] It should be noted that, when the plurality of second light-emitting layers 25 include: a plurality of second blue light-emitting layers 25B, a plurality of second red light-emitting layers 25R and a plurality of second green light-emitting layers 25G, the above n m is the refractive index of the mth film layer among the above d film layers for the central wavelength of red light, green light or blue light.

[0223] Exemplarily, when interference of blue light is required, the above λ is the wavelength of blue light; when interference of red light is required, the above λ is the wavelength of red light; when interference of green light is required, the above λ is the wavelength of green light.

[0224] Exemplarily, when L of the red sub-microcavity A1-R satisfies the above formula, the red light emitted by the second red light-emitting layer 25R can produce a microcavity effect in the red sub-microcavity A1-R, thereby increasing the brightness and color purity of the red light.

[0225] Similarly, the green light emitted by the second green light-emitting layer 25G and the blue light emitted by the second blue light-emitting layer 25B can also produce a microcavity effect in the corresponding sub-microcavity A1, thereby increasing the brightness and color purity of the green and blue lights.

[0226] In some embodiments, the length of the blue sub-microcavity A1-B is shorter than that of the red sub-microcavity A1-R. The length of the blue sub-microcavity A1-B is shorter than that of the green sub-microcavity A1-G.

[0227] For example, the wavelength of red light ranges from 615nm to 630nm, the wavelength of green light ranges from 515nm to 535nm, and the wavelength of red light ranges from 460nm to 475nm. Therefore, when red light, green light, and blue light can all produce microcavity effects, the length of the blue sub-microcavity A1-B is the smallest.

[0228] It should be noted that any one of the first auxiliary layer 22, the second auxiliary layer 24, and the third auxiliary layer 26 may include one film layer or multiple film layers stacked in sequence. In the case where any one of the first auxiliary layer 22, the second auxiliary layer 24, and the third auxiliary layer 26 includes multiple film layers, each film layer may have different functions, so that the first auxiliary layer 22, the second auxiliary layer 24, and the third auxiliary layer 26 can have multiple functions.

[0229] In some examples, such as Figure 7 As shown, the first auxiliary layer 22 includes a light-transmitting conductive layer 221 , a hole injection layer 222 , a first hole transport layer 223 and an electron blocking layer 224 .

[0230] The light-transmitting conductive layer 221 has good light transmittance and conductivity. When light is directed toward the light-transmitting conductive layer 221, the light can pass through the light-transmitting conductive layer 221 and be directed toward the anode layer 21. The anode layer 21 has good light reflecting performance, so the light can be reflected between the anode layer 21 and the light-transmitting conductive layer 221.

[0231] For example, the material of the light-transmitting conductive layer 221 may include ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), and the like.

[0232] Exemplarily, the thickness of the light-transmitting conductive layer 221 is less than or equal to 10 nm. Optionally, the thickness of the light-transmitting conductive layer 221 ranges from 5 nm to 10 nm.

[0233] For example, the thickness of the light-transmitting conductive layer 221 can be 5 nm, 6.5 nm, 8 nm, 9 nm, or 10 nm.

[0234] Exemplarily, the hole injection layer 222 can be formed by doping P-type dopants (such as MnO3, F4TCNQ, etc.) into the material of the first hole transport layer 223, the doping ratio of the P-type dopant is less than or equal to 5%, and the thickness of the hole injection layer 222 is less than or equal to 10nm.

[0235] For example, the doping ratio of the P-type dopant in the material of the first hole transport layer 223 may be 1%, 2%, 3%, 4% or 5%, etc. The thickness of the hole injection layer 222 may be 1 nm, 3 nm, 5 nm, 8 nm or 10 nm, etc.

[0236] For example, the material of the first hole transport layer 223 includes a carbazole material having a high hole mobility. The first hole transport layer 223 can be formed by an evaporation process.

[0237] Exemplarily, the thickness of the electron blocking layer 224 is less than or equal to 10 nm. For example, the thickness of the electron blocking layer 224 can be 1 nm, 3 nm, 5 nm, 8 nm, or 10 nm.

[0238] For example, the HOMO (Highest Occupied Molecular Orbital) energy level of the hole injection layer 222 material, the HOMO energy level of the first hole transport layer 223 material, and the HOMO energy level of the electron blocking layer 224 material increase successively. This arrangement can reduce the hole injection barrier and increase the hole mobility, which is beneficial for the holes to be injected from the anode layer 21 and transported to the first light-emitting layer 23 in sequence, thereby increasing the accumulation of holes in the first light-emitting layer 23 and improving the luminous efficiency and luminous life of the first light-emitting layer 23.

[0239] For example, the HOMO energy level of the material of the first hole transport layer 223 ranges from -5.2 eV to -5.6 eV. For example, the HOMO energy level of the material of the first hole transport layer 223 may be -5.2 eV, -5.3 eV, -5.4 eV, -5.5 eV, or -5.6 eV.

[0240] Exemplarily, the HOMO energy level of the material of the electron blocking layer 224 ranges from -5.5 eV to -5.9 eV. For example, the HOMO energy level of the material of the electron blocking layer 224 includes: -5.5 eV, -5.6 eV, -5.7 eV, -5.8 eV, -5.9 eV, etc.

[0241] Illustratively, the T1 of the material of the electron blocking layer 224 is greater than the T1 of the light-emitting material in the first light-emitting layer 23, which can prevent electrons and / or excitons from leaking from the first light-emitting layer 23, maintain the concentration of electrons and / or excitons in the first light-emitting layer 23, and ensure the luminous efficiency of the first light-emitting layer 23.

[0242] For example, the T1 of the material of the electron blocking layer 224 is at least 0.2 eV higher than the T1 of the light-emitting material in the first light-emitting layer 23 .

[0243] In some examples, such as Figure 7 As shown, the second auxiliary layer 24 includes a first hole blocking layer 241 , a first electron transport layer 242 , a first charge generation layer 243 , a second charge generation layer 244 and a microcavity regulating layer 245 .

[0244] Illustratively, the HOMO energy level absolute value of the material of the first hole blocking layer 241 is greater than the HOMO energy level absolute value of the material of the first light emitting layer 23. The first hole blocking layer 241 is used to prevent holes and / or excitons from leaking from the first light emitting layer 23.

[0245] For example, the absolute value of the HOMO energy level of the material of the first hole blocking layer 241 is greater than the absolute value of the HOMO energy level of the material of the first light emitting layer 23 by at least 0.2 eV.

[0246] Illustratively, the T1 of the material of the first hole blocking layer 241 is higher than the T1 of the light-emitting material included in the first light-emitting layer 23 .

[0247] For example, the T1 of the material of the first hole blocking layer 241 is higher than the T1 of the light emitting material included in the first light emitting layer 23 by at least 0.2 eV.

[0248] Exemplarily, the material of the first hole blocking layer 241 includes triazine materials and the like.

[0249] Exemplarily, the thickness of the first hole blocking layer 241 is less than or equal to 10 nm. For example, the thickness of the first hole blocking layer 241 is 1 nm, 3 nm, 5 nm, 8 nm, or 10 nm.

[0250] Exemplary materials for the first electron transport layer 242 include at least one of a thiophene material, an imidazole material, an azine derivative material, and lithium quinoline. The first electron transport layer 242 can be prepared by blending a thiophene, imidazole, or azine derivative with lithium quinoline, where the weight percentage of lithium quinoline is in the range of 30% to 70%.

[0251] For example, the mass proportion of the lithium quinoline is 30%, 40%, 50%, 60% or 70%.

[0252] Exemplarily, the thickness of the first electron transport layer 242 ranges from 15 nm to 50 nm. For example, the thickness of the first electron transport layer 242 is 15 nm, 23 nm, 35 nm, 40 nm, or 50 nm.

[0253] Exemplarily, the first charge generation layer 243 and the second charge generation layer 244 are used to enable the first light emitting layer 23 and the second light emitting layer 25 in the light emitting device layer 2 to form series light emission, thereby increasing the overall light emitting brightness of the display substrate 100 .

[0254] For example, the first charge generation layer 243 can be formed by doping the material of the first electron transport layer 242 with a low-functionality metal (such as lithium (Li), ytterbium (Yb), calcium (Ca), etc.), with the doping ratio being less than or equal to 5%. The thickness of the first charge generation layer 243 is less than or equal to 10 nm.

[0255] For example, the doping ratio of the low-functionality metal may be 1%, 2%, 3%, 4% or 5%, etc. The thickness of the first charge generation layer 243 may be 1 nm, 3 nm, 5 nm, 8 nm or 10 nm, etc.

[0256] For example, the second charge generation layer 244 can be formed by doping a P-type dopant (such as MnO3 or F4TCNQ) into the second hole transport layer 245 material described below, with the doping ratio being less than or equal to 5%. The thickness of the first charge generation layer 243 is less than or equal to 10 nm.

[0257] For example, the doping ratio of the P-type dopant may be 1%, 2%, 3%, 4% or 5%, etc. The thickness of the second charge generation layer 244 may be 1 nm, 3 nm, 5 nm, 8 nm or 10 nm, etc.

[0258] Alternatively, the first charge generation layer 243 may also be referred to as an N-type charge generation layer (N-CGL), and the second charge generation layer 244 may also be referred to as a P-type charge generation layer (P-CGL).

[0259] Exemplarily, the thickness of the microcavity adjustment layer 245 is adjustable. By adjusting the thickness of the microcavity adjustment layer 245 , the lengths of the multiple sub-microcavities A1 can be adjusted so that the light corresponding to the multiple sub-microcavities A1 can all produce a microcavity effect.

[0260] In some embodiments, as Figure 6 As shown, the microcavity adjustment layer 245 includes: a second hole transport layer 2451; a red sub-microcavity adjustment layer 245R disposed between the second hole transport layer 2451 and the second red light-emitting layer 25R; a green sub-microcavity adjustment layer 245G disposed between the second hole transport layer 2451 and the second green light-emitting layer 25G; and a blue sub-microcavity adjustment layer 245B disposed between the second hole transport layer 2451 and the second blue light-emitting layer 25B. The red sub-microcavity adjustment layer 245R and the blue sub-microcavity adjustment layer 245B have different thicknesses, and the green sub-microcavity adjustment layer 245G and the blue sub-microcavity adjustment layer 245B have different thicknesses.

[0261] For example, the material of the second hole transport layer 245 includes a carbazole material having a high hole mobility. The second hole transport layer 245 can be formed by an evaporation process.

[0262] Illustratively, the second hole transport layer 245 is used to lower the hole injection barrier and improve the hole mobility, which is beneficial for the hole transport to the second light-emitting layer 25, thereby increasing the accumulation of holes in the second light-emitting layer 25 and improving the luminous efficiency and luminous lifetime of the second light-emitting layer 25.

[0263] For example, the HOMO energy level of the material of the second hole transport layer 245 ranges from -5.2 eV to -5.6 eV. For example, the HOMO energy level of the material of the second hole transport layer 245 includes: -5.2 eV, -5.3 eV, -5.4 eV, -5.5 eV, -5.6 eV, etc.

[0264] Exemplarily, the T1 of the materials of the red sub-microcavity adjustment layer 245R, the green sub-microcavity adjustment layer 245G, and the blue sub-microcavity adjustment layer 245B is higher than the T1 of the light-emitting material of the second light-emitting layer 25 .

[0265] For example, the T1 of the materials of the red sub-microcavity adjustment layer 245R, the green sub-microcavity adjustment layer 245G, and the blue sub-microcavity adjustment layer 245B is at least 0.2 eV higher than the T1 of the light-emitting material of the second light-emitting layer 25 .

[0266] Exemplarily, the thickness of the blue sub-microcavity adjustment layer 245B is less than or equal to 10 nm.

[0267] For example, the thickness of the blue sub-microcavity adjustment layer 245B can be 1 nm, 3 nm, 5 nm, 7 nm, or 10 nm.

[0268] Exemplarily, the thickness of the second hole transport layer 2451, the thickness of the red sub-microcavity adjustment layer 245R, the thickness of the green sub-microcavity adjustment layer 245G, and the thickness of the blue sub-microcavity adjustment layer 245B are all individually adjustable. By adjusting the thickness of the second hole transport layer 2451, the thickness of the red sub-microcavity adjustment layer 245R, the thickness of the green sub-microcavity adjustment layer 245G, and the thickness of the blue sub-microcavity adjustment layer 245B, the lengths of the multiple sub-microcavities A1 can be adjusted so that the light corresponding to the multiple sub-microcavities A1 can produce a microcavity effect.

[0269] As mentioned above, the wavelengths of red light, green light, and blue light are different. When red light, green light, and blue light can all produce microcavity effects, the lengths between the red photon microcavity A1-R and the blue photon microcavity A1-B are different, and the lengths between the green photon microcavity A1-G and the blue photon microcavity A1-B are different. Figure 6As shown, multiple sub-microcavities A1 share the first auxiliary layer 22, the first light-emitting layer 23, part of the film layers in the second auxiliary layer 24, and the third auxiliary layer 26. By making the thicknesses of the red sub-microcavity adjustment layer 245R and the blue sub-microcavity adjustment layer 245B in the second auxiliary layer 24 different, and making the thicknesses of the green sub-microcavity adjustment layer 245G and the blue sub-microcavity adjustment layer 245B in the second auxiliary layer 24 different, the multiple sub-microcavities A1 can be made to meet the required length by only adjusting the thicknesses of the red sub-microcavity adjustment layer 245R, the green sub-microcavity adjustment layer 245G, and the blue sub-microcavity adjustment layer 245B. The thicknesses of the above-mentioned shared film layers (such as the first auxiliary layer 22, the first light-emitting layer 23, and the third auxiliary layer 26) in the blue sub-microcavity A1-B, the red sub-microcavity A1-R, and the green sub-microcavity A1-G can be made the same. This can simplify the manufacturing process of the above-mentioned shared film layers, and accordingly, simplify the manufacturing process of the display substrate 100.

[0270] It should be noted that the thickness of the second hole transport layer 2451, the red sub-microcavity adjustment layer 245R, the green sub-microcavity adjustment layer 245G and the blue sub-microcavity adjustment layer 245B has little effect on the electrical properties of the light-emitting device layer 2 in the display substrate 100. By adjusting the thickness of the second hole transport layer 2451, the red sub-microcavity adjustment layer 245R, the green sub-microcavity adjustment layer 245G and the blue sub-microcavity adjustment layer 245B, thereby adjusting the lengths of the multiple sub-microcavities A1, the impact on the electrical properties of the light-emitting device layer 2 in the display substrate 100 can be reduced.

[0271] It can be understood that any one of the red sub-microcavity adjustment layer 245R, the green sub-microcavity adjustment layer 245G, and the blue sub-microcavity adjustment layer 245B can include one film layer, or any one of the red sub-microcavity adjustment layer 245R, the green sub-microcavity adjustment layer 245G, and the blue sub-microcavity adjustment layer 245B can include multiple film layers stacked in sequence.

[0272] In some embodiments, as Figure 3 As shown, the red sub-microcavity adjustment layer 245R includes a red hole transport layer 245R-1 and a red electron blocking layer 245R-2 stacked in sequence along a direction away from the back plate 1, and the green sub-microcavity adjustment layer 245G includes a green hole transport layer 245G-1 and a green electron blocking layer 245G-2 stacked in sequence along a direction away from the back plate 1.

[0273] For example, the red hole transport layer 245R-1 can lower the hole injection barrier, facilitating the injection and transfer of holes from the second auxiliary layer 24 into the second red light-emitting layer 25G, thereby increasing the accumulation of holes in the second red light-emitting layer 25G and improving the luminous efficiency and luminous lifetime of the second red light-emitting layer 25G. The green hole transport layer 245G-1 can lower the hole injection barrier, facilitating the injection and transfer of holes from the second auxiliary layer 24 into the second green light-emitting layer 25G, thereby increasing the accumulation of holes in the second green light-emitting layer 25G and improving the luminous efficiency and luminous lifetime of the second green light-emitting layer 25G.

[0274] Exemplarily, the red electron blocking layer 245R-2 is used to block electrons and / or excitons from escaping from the second red light-emitting layer 25G, thereby confining the electrons and / or excitons in the second red light-emitting layer 25G, thereby increasing the concentration of electrons and / or excitons in the second red light-emitting layer 25G, and thereby improving the luminance and luminous efficiency of the second red light-emitting layer 25G. The green electron blocking layer 245G-2 is used to block electrons and / or excitons from escaping from the second green light-emitting layer 25G, thereby confining the electrons and / or excitons in the second green light-emitting layer 25G, thereby increasing the concentration of electrons and / or excitons in the second green light-emitting layer 25G, and thereby improving the luminance and luminous efficiency of the second green light-emitting layer 25G.

[0275] In some examples, the red hole transport layer 245R- 1 and the green hole transport layer 245G- 1 are respectively used to adjust the length of the sub-microcavity A1 .

[0276] It can be understood that when the thickness of other film layers (such as the first auxiliary layer 22, the first light-emitting layer 23, etc.) remains unchanged, the lengths of the corresponding red sub-microcavity A1-R and green sub-microcavity A1-G can be changed by changing the thickness of the red hole transport layer 245R-1 and the green hole transport layer 245G-1.

[0277] For example, by changing the thickness of the red hole transport layer 245R-1, the length of the red sub-microcavity A1-R can be changed; thereby, the red light can produce a microcavity effect in the red sub-microcavity A1-R, thereby increasing the brightness and color purity of the red light. Furthermore, the wavelength of light that can produce a microcavity effect in the red sub-microcavity A1-R can be changed, thereby adjusting the color of the light emitted from the red sub-microcavity A1-R. By changing the thickness of the green hole transport layer 245G-1, the length of the green sub-microcavity A1-G can be changed; thereby, the green light can produce a microcavity effect in the green sub-microcavity A1-G, thereby increasing the brightness and color purity of the green light. Furthermore, the wavelength of light that can produce a microcavity effect in the green sub-microcavity A1-G can be changed, thereby adjusting the color of the light emitted from the green sub-microcavity A1-G.

[0278] In some examples, such as Figure 7 As shown, the third auxiliary layer 26 includes a second hole blocking layer 261 , a second electron transport layer 262 and an electron injection layer 263 .

[0279] Illustratively, the HOMO energy level absolute value of the material of the second hole blocking layer 261 is greater than the HOMO energy level absolute value of the material of the second light emitting layer 25. The second hole blocking layer 261 is used to prevent holes and / or excitons from leaking from the second light emitting layer 25.

[0280] For example, the absolute value of the HOMO energy level of the material of the second hole blocking layer 261 is greater than the absolute value of the HOMO energy level of the material of the second light emitting layer 25 by at least 0.2 eV.

[0281] Illustratively, the T1 of the material of the second hole blocking layer 261 is higher than the T1 of the light-emitting material included in the second light-emitting layer 25 .

[0282] For example, the T1 of the material of the second hole blocking layer 261 is higher than the T1 of the light emitting material included in the second light emitting layer 25 by at least 0.2 eV.

[0283] Exemplarily, the material of the second hole blocking layer 261 includes triazine materials and the like.

[0284] Exemplarily, the thickness of the second hole blocking layer 261 is less than or equal to 10 nm. For example, the thickness of the second hole blocking layer 261 can be 1 nm, 3 nm, 5 nm, 8 nm, or 10 nm.

[0285] Exemplarily, the material of the second electron transport layer 262 includes at least one of a thiophene material, an imidazole material, an azine derivative material, and lithium quinoline. The second electron transport layer 262 can be prepared by blending a thiophene material, an imidazole material, or an azine derivative material with lithium quinoline, wherein the weight percentage of lithium quinoline ranges from 30% to 70%.

[0286] For example, the mass proportion of the lithium quinoline may be 30%, 40%, 50%, 60% or 70%.

[0287] Exemplarily, the thickness of the second electron transport layer 262 ranges from 15 nm to 50 nm. For example, the thickness of the second electron transport layer 262 can be 15 nm, 23 nm, 35 nm, 40 nm, or 50 nm.

[0288] Illustratively, the electron injection layer 263 is used to lower the electron injection barrier, which is beneficial for electrons to be injected from the cathode layer 27 and transferred to the second light-emitting layer 25, thereby increasing the accumulation of electrons in the second light-emitting layer 25 and improving the luminous efficiency and luminous lifetime of the second light-emitting layer 25.

[0289] For example, the material of the electron injection layer 263 includes lithium fluoride (LiF), ytterbium (Yb), or calcium (Ca), etc. The electron injection layer 263 can be formed by an evaporation process.

[0290] Exemplarily, the thickness of the electron injection layer 263 ranges from 0.5 nm to 2 nm. For example, the thickness of the electron injection layer 263 can be 0.5 nm, 0.8 nm, 1.2 nm, 1.7 nm, or 2 nm.

[0291] In some examples, such as Figure 7 As shown, the display substrate 100 further includes: an optical cover layer 3 and / or an encapsulation layer 4 sequentially stacked on the cathode layer 27 .

[0292] Exemplarily, the material of the optical cover layer 3 includes a high-refractive-index organic material. For example, the refractive index of the optical cover layer 3 for light with a wavelength of 530 nm is greater than 1.9.

[0293] Exemplarily, the thickness of the optical cover layer 3 is less than or equal to 100 nm. For example, the thickness of the optical cover layer 3 can be 10 nm, 30 nm, 50 nm, 80 nm, or 100 nm.

[0294] Exemplarily, the encapsulation layer 4 can prevent the film layers (such as the first light-emitting layer 23 and the second light-emitting layer 25 ) in the display substrate 100 from contacting with water and oxygen in the air, thereby reducing the aging rate of the above film layers and extending the service life of the display substrate 100 .

[0295] Exemplarily, the packaging type of the packaging layer 4 includes: frame glue packaging or thin film packaging, etc.

[0296] It should be noted that the plurality of second light-emitting layers 25 are located in the same layer and constitute a light-emitting layer group. The present disclosure does not limit the number of first light-emitting layers 23 and the number of light-emitting layer groups, that is, the number of first light-emitting layers 23 and the number of light-emitting layer groups can be one or more.

[0297] In some examples, such as Figure 8 As shown, there are multiple first light-emitting layers 23, and a second auxiliary layer 24 is provided between any two adjacent first light-emitting layers 23; and / or Figure 9 As shown, there are multiple light-emitting layer groups, and a third auxiliary layer 26 is provided between any two adjacent light-emitting layer groups.

[0298] For example, the number of the first light-emitting layers 23 is 2, 3, 4, 5 or 6.

[0299] By providing multiple first light-emitting layers 23 , the total intensity of light emitted by the first light-emitting layer 23 can be increased, thereby increasing the intensity of the excitation light of the second light-emitting layer 25 and improving the luminance of the display substrate 100 .

[0300] By setting up multiple light-emitting layer groups, the total intensity of light that the light-emitting layer groups can emit can be increased, thereby increasing the light-emitting layer groups' absorption of light emitted by the first light-emitting layer 23, thereby increasing the intensity of the excitation light of the light-emitting layer groups, and increasing the luminous brightness of the display substrate 100.

[0301] By providing a second auxiliary layer 24 between any two adjacent first light-emitting layers 23 and a third auxiliary layer 26 between any two adjacent light-emitting layer groups, it is possible to ensure that holes and electrons can be transferred to multiple first light-emitting layers 23 and light-emitting layer groups to generate excitons, thereby causing the first light-emitting layers 23 and light-emitting layer groups to emit light.

[0302] The inventors of the present disclosure have verified the color purity and luminous efficiency of the display substrate 100 of the present disclosure.

[0303] Verification Example 1: includes Comparative Example 1 and Example 1.

[0304] In Comparative Example 1, one display substrate has a red light-emitting device, a green light-emitting device, and a blue light-emitting device, and the other display substrate has a first blue light-emitting device. Both display substrates include an anode layer, a light-transmitting conductive layer, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer (e.g., a red light-emitting layer, a green light-emitting layer, or a blue light-emitting layer), a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode layer, which are stacked in sequence.

[0305] In the above-mentioned comparative example 1, the red light-emitting layer in the red light-emitting device includes a red host material and a red phosphorescent light-emitting material, and the mass proportion of the red phosphorescent light-emitting material is 5%; the green light-emitting layer in the green light-emitting device includes a green host material and a green phosphorescent light-emitting material with multiple resonance characteristics, and the mass proportion of the green phosphorescent light-emitting material is 5%; the blue light-emitting layer in the blue light-emitting device includes a blue host material and a deep blue fluorescent material (the peak value of the emission spectrum is 460nm), and the mass proportion of the deep blue fluorescent material is 5%. The blue light-emitting layer of the first blue light-emitting device includes an ordinary P-type blue host material, a blue light-emitting material with thermally activated delayed fluorescence characteristics (the peak value of the emission spectrum is 500nm), and a boron-containing blue fluorescent material with multiple resonance characteristics (the peak value of the emission spectrum is 470nm), and the mass proportions of the above three materials are 79%, 20%, and 1%, respectively.

[0306] The thicknesses of the film layers corresponding to the light-emitting devices in the display substrates of Comparative Example 1 are shown in Table 1 below.

[0307] Table 1

[0308]

[0309] The display substrate 100 of Example 1 has a red light-emitting device, a green light-emitting device, and a blue light-emitting device. The display substrate 100 includes: an anode layer, a light-transmitting conductive layer, a hole injection layer, a first hole transport layer, an electron blocking layer, a first light-emitting layer, a first hole blocking layer, a first electron transport layer, a first charge generation layer, a second charge generation layer, a second hole transport layer, microcavity adjustment layers of various colors, second light-emitting layers of various colors, a second hole blocking layer, a second electron transport layer, an electron injection layer, and a cathode layer.

[0310] In Example 1, the material of the first light-emitting layer 23 is the same as the light-emitting layer material of the first blue light-emitting device in Comparative Example 1, including an ordinary P-type blue main material, a blue light-emitting material with thermally activated delayed fluorescence characteristics (the peak value of the emission spectrum is 500nm), and a boron-containing blue fluorescent material with multiple resonance characteristics (the peak value of the emission spectrum is 470nm), and the mass proportions of the above three materials are 79%, 20%, and 1%, respectively.

[0311] In the above-mentioned embodiment 1, the second light-emitting layer 25 in the red light-emitting device includes a red main material and a red phosphorescent material, and the mass proportion of the red phosphorescent material is 5%; the second light-emitting layer 25 in the green light-emitting device includes a green main material and a green phosphorescent material with multiple resonance characteristics, and the mass proportion of the green phosphorescent material is 5%; the second light-emitting layer 25 in the blue light-emitting device includes a blue main material and a deep blue fluorescent material (the peak value of the emission spectrum is 460nm), and the mass proportion of the deep blue fluorescent material is 5%.

[0312] The thickness of each film layer corresponding to each light-emitting device in the display substrate 100 of Example 1 is shown in Table 2 below.

[0313] Table 2

[0314] project Red light emitting device Green light-emitting devices Blue light-emitting devices Anode layer thickness (nm) 100 100 100 Thickness of light-transmitting conductive layer (nm) 8 8 8 Thickness of hole injection layer (nm) 10 10 10 Thickness of the first hole transport layer (nm) 25 25 25 Electron blocking layer thickness (nm) 5 5 5 Thickness of the first light-emitting layer (nm) 30 30 30 Thickness of the first hole blocking layer (nm) 6 6 6 Thickness of the first electron transport layer (nm) 10 10 10 Thickness of the first charge generation layer (nm) 10 10 10 Thickness of the second charge generation layer (nm) 10 10 10 Thickness of the second hole transport layer (nm) 40 40 40 Thickness of each color sub-microcavity adjustment layer (nm) 15 15 15 Thickness of the second light-emitting layer (nm) 25 30 30 Thickness of the second hole blocking layer (nm) 10 10 10 Thickness of the second electron transport layer (nm) 35 35 35 Electron injection layer thickness (nm) 1 1 1 Cathode layer thickness (nm) 15 15 15 Optical cover layer thickness (nm) 75 75 75

[0315] In Comparative Example 1 and Example 1, the P-type doping ratio of the hole injection layer is 3%. The cathode layer is made of a magnesium-silver alloy with a mass ratio of magnesium to silver of 1:9. The electron transport layer is made of (8-hydroxyquinoline) lithium.

[0316] like Figure 10As shown in the graph, the abscissa is wavelength (in nm), and the ordinate is spectral relative intensity. The emission spectra p1 of the first blue light-emitting device of Comparative Example 1 and the first light-emitting layer 23 of the blue light-emitting device of Example 1 clearly have a bimodal characteristic. The bimodal characteristic is caused by the superposition of the emission spectra of the blue light-emitting material with thermally activated delayed fluorescence (emission spectrum peak at 500 nm) and the boron-containing blue fluorescent material with multi-resonance characteristics (emission spectrum peak at 470 nm) in the first light-emitting layer 23. The absorption spectrum p2 of the red phosphorescent material of the second light-emitting layer 25 of the red light-emitting device of Example 1 overlaps with the emission spectrum p1 of the first light-emitting layer 23 of the blue light-emitting device. The comparative relationship between the relevant quantities in Comparative Example 1 and Example 1 and the first blue light-emitting device is shown in Table 3.

[0317] Among them, the driving voltage of the first blue light-emitting device is 4.5V, the luminous brightness is 1000, the color coordinates are (0.17, 0.32), and the luminous efficiency is 38cd / A.

[0318] Table 3

[0319]

[0320] The above results show that, compared to Comparative Example 1, the light-emitting device in Example 1, which combines the first light-emitting layer 23 and the second light-emitting layer 25 in series, exhibits several times higher efficiency and several times longer lifetime at the same brightness for both the blue and green light-emitting devices. The red light-emitting devices in the second light-emitting layer 25 do not contain any luminescent material that can be excited by the light emitted by the first light-emitting layer 23. Therefore, the red light-emitting devices in the second light-emitting layer 25 maintain their original efficiency levels. Furthermore, due to microcavity modulation, the color purity of the red light emitted by the red light-emitting layer is not affected. Although the lifetime of the red light-emitting layer has decreased, it still remains at a high level.

[0321] Verification Example 2: includes Comparative Example 2 and Example 2.

[0322] In Comparative Example 2, one display substrate has a red light-emitting device, a green light-emitting device, and a blue light-emitting device, and the other display substrate has a first green light-emitting device. The film layers included in the two display substrates are the same as those included in the display substrate in Comparative Example 1.

[0323] In Comparative Example 2, the light-emitting layer in the red light-emitting device includes a P-type red main material, an N-type red main material with thermally activated delayed fluorescence characteristics, and a red fluorescent light-emitting material, and the mass proportions of the above three materials are 69%, 30%, and 1%, respectively; the light-emitting layer in the green light-emitting device includes a green main material and a green fluorescent light-emitting material with multiple resonance characteristics, and the mass proportion of the green fluorescent light-emitting material is 1%; the light-emitting layer in the blue light-emitting device includes a blue main material and a deep blue fluorescent material (the peak value of the emission spectrum is 460nm), and the mass proportion of the deep blue fluorescent material is 5%.

[0324] The thickness of each film layer corresponding to each light-emitting device in the display substrate of Comparative Example 2 is shown in Table 4 below.

[0325] Table 4

[0326]

[0327] The structure of the display substrate 100 of the second embodiment is the same as that of the display substrate 100 of the first embodiment.

[0328] In Example 2, the material of the first light-emitting layer 23 is the same as the material of the light-emitting layer of the first green light-emitting device in Comparative Example 2, including an ordinary P-type green main material and a green light-emitting material with thermally activated delayed fluorescence characteristics (the peak value of the emission spectrum is 460nm), and the mass proportion of the above-mentioned green light-emitting material with thermally activated delayed fluorescence characteristics is 30%.

[0329] In Example 2, the second light-emitting layer 25 in the red light-emitting device includes a P-type red main material, an N-type red main material with thermally activated delayed fluorescence characteristics, and a red fluorescent light-emitting material, and the mass proportions of the above three materials in the second light-emitting layer 25 are 69%, 30%, and 1%, respectively; the second light-emitting layer 25 in the green light-emitting device includes a green main material and a green fluorescent light-emitting material with multiple resonance characteristics, and the mass proportion of the green fluorescent light-emitting material is 1%; the second light-emitting layer 25 in the blue light-emitting device includes a blue main material and a deep blue fluorescent material (the peak value of the emission spectrum is 460nm), and the mass proportion of the deep blue fluorescent material in the second light-emitting layer 25 is 5%.

[0330] The thickness of each film layer corresponding to each light-emitting device in the display substrate 100 of Example 2 is shown in Table 5 below.

[0331] Table 5

[0332] project Red light emitting device Green light-emitting devices Blue light-emitting devices Anode layer thickness (nm) 100 100 100 Thickness of light-transmitting conductive layer (nm) 8 8 8 Thickness of hole injection layer (nm) 10 10 10 Thickness of the first hole transport layer (nm) 25 25 25 Electron blocking layer thickness (nm) 5 5 5 Thickness of the first light-emitting layer (nm) 30 30 30 Thickness of the first hole blocking layer (nm) 8 8 8 Thickness of the first electron transport layer (nm) 10 10 10 Thickness of the first charge generation layer (nm) 8 8 8 Thickness of the second charge generation layer (nm) 10 10 10 Thickness of the second hole transport layer (nm) 40 40 40 Thickness of each color sub-microcavity adjustment layer (nm) 15 15 15 Thickness of the second light-emitting layer (nm) 20 20 20 Thickness of the second hole blocking layer (nm) 10 10 10 Thickness of the second electron transport layer (nm) 35 35 35 Electron injection layer thickness (nm) 1 1 1 Cathode layer thickness (nm) 15 15 15

[0333] The P-type doping ratio of the hole injection layer is 3%. The cathode layer is made of magnesium-silver alloy, and the mass ratio of magnesium to silver in the magnesium-silver alloy is 1:9. The electron transport layer is made of (8-hydroxyquinoline) lithium.

[0334] like Figure 11 As shown in the graph, the abscissa represents wavelength (nm), and the ordinate represents relative spectral intensity. The emission spectrum p3 of the first green light-emitting device in Comparative Example 2 and the first light-emitting layer 23 in Example 2 clearly exhibits a single peak, overlapping with the absorption spectrum p4 of the second light-emitting layer 25 of the red light-emitting device in Example 2 and the absorption spectrum p5 of the second light-emitting layer 25 of the green light-emitting device in Example 2. Table 6 shows a comparison of the relevant quantities in Comparative Example 2 and Example 2 with those of the first green light-emitting device.

[0335] In comparative example 2, the driving voltage of the first green light-emitting device is 3.6 V, the luminance is 10000, the color coordinates are (0.34, 0.60), and the luminous efficiency is 53 cd / A.

[0336] Table 6

[0337]

[0338] The above results show that, in Example 2, after the first light-emitting layer 23 and the second light-emitting layer 25 are connected in series, both the red and green light-emitting devices exhibit higher efficiency and a longer lifespan at the same brightness compared to Comparative Example 2. The second light-emitting layer 25 of the blue light-emitting device does not receive any additional gain from the first light-emitting layer 23, maintaining similar efficiency and lifespan to the blue light-emitting device in Comparative Example 1.

[0339] Verification Example 3: includes Example 3-1 and Example 3-2.

[0340] The display substrates 100 of Examples 3-1 and 3-2 each have a red light-emitting device, a green light-emitting device, and a blue light-emitting device. The display substrates 100 of Examples 3-1 and 3-2 each include an anode layer, a light-transmitting conductive layer, a hole injection layer, a first hole transport layer, an electron blocking layer, a first light-emitting layer, a first hole blocking layer, a first electron transport layer, a first charge generation layer, a second charge generation layer, a second hole transport layer, microcavity adjustment layers of various colors, second light-emitting layers of various colors, a second hole blocking layer, a second electron transport layer, an electron injection layer, a cathode layer, and an optical cover layer, which are stacked in sequence.

[0341] The thickness of each film layer in the display substrate 100 of Example 3-1 is shown in Table 7 below.

[0342] Table 7

[0343] project Red light emitting device Green light-emitting devices Blue light-emitting devices Anode layer thickness (nm) 100 100 100 Thickness of light-transmitting conductive layer (nm) 8 8 8 Thickness of hole injection layer (nm) 10 10 10 Thickness of the first hole transport layer (nm) 25 25 25 Electron blocking layer thickness (nm) 5 5 5 Thickness of the first light-emitting layer (nm) 30 30 30 Thickness of the first hole blocking layer (nm) 6 6 6 Thickness of the first electron transport layer (nm) 10 10 10 Thickness of the first charge generation layer (nm) 10 10 10 Thickness of the second charge generation layer (nm) 10 10 10 Thickness of the second hole transport layer (nm) 39 39 39 Thickness of each color sub-microcavity adjustment layer (nm) 15 15 15 Thickness of the second light-emitting layer (nm) 25 30 20 Thickness of the second hole blocking layer (nm) 10 10 10 Thickness of the second electron transport layer (nm) 35 35 35 Electron injection layer thickness (nm) 1 1 1 Cathode layer thickness (nm) 15 15 15

[0344] The thickness of each film layer in the display substrate 100 of Example 3-2 is shown in Table 8 below.

[0345] Table 8

[0346] project Red light emitting device Green light-emitting devices Blue light-emitting devices Anode layer thickness (nm) 100 100 100 Thickness of light-transmitting conductive layer (nm) 8 8 8 Thickness of hole injection layer (nm) 10 10 10 Thickness of the first hole transport layer (nm) 40 40 40 Electron blocking layer thickness (nm) 5 5 5 Thickness of the first light-emitting layer (nm) 30 30 30 Thickness of the first hole blocking layer (nm) 6 6 6 Thickness of the first electron transport layer (nm) 10 10 10 Thickness of the first charge generation layer (nm) 8 8 8 Thickness of the second charge generation layer (nm) 8 8 8 Thickness of the second hole transport layer (nm) 24 24 24 Thickness of each color sub-microcavity adjustment layer (nm) 10 10 10 Thickness of the second light-emitting layer (nm) 25 30 20 Thickness of the second hole blocking layer (nm) 10 10 10 Thickness of the second electron transport layer (nm) 35 35 35 Electron injection layer thickness (nm) 1 1 1 Cathode layer thickness (nm) 15 15 15 Optical cover layer thickness (nm) 75 75 75

[0347] The P-type doping ratio of the hole injection layer in Examples 3-1 and 3-2 is 3%. The cathode layer is made of a magnesium-silver alloy with a mass ratio of magnesium to silver of 1:9. The electron transport layer is made of (8-hydroxyquinoline) lithium.

[0348] In Example 3-2, compared to Example 3-1, the optical thickness L1 can be adjusted by adjusting the thickness of the first hole transport layer near the anode layer 21, and the length of each sub-microcavity A1 can be corrected by adjusting the thickness of the second hole transport layer away from the anode layer 21. That is, the thickness of the first hole transport layer near the anode layer 21 in Example 3-2 is 40 nm - 25 nm = 15 nm greater than the thickness of the first hole transport layer near the anode layer 21 in Example 3-1, and the thickness of the second hole transport layer far from the anode layer 21 in Example 3-2 is 15 nm less than the thickness of the second hole transport layer far from the anode layer 21 in Example 3-1.

[0349] The results of the luminous purity and luminous efficiency of the above-mentioned Example 3-1 relative to Example 3-2 are shown in Table 9.

[0350] Table 9

[0351]

[0352] From the above results, it can be seen that the blue light-emitting device in Example 3-2 has low luminous efficiency and low color purity. This is mainly because the size deviation of the blue light-emitting device corresponding to the above L1, L2, and L3 distance optimization is too large and does not meet the formula: |L1-L3|≤30nm, which results in an excessively high long-wavelength mode component in the blue sub-microcavity A1-B.

[0353] Some other embodiments of the present disclosure further provide a display substrate 100, such as Figure 12 As shown, the display substrate 100 includes: a back plate 1 and a light emitting device layer 2 .

[0354] In some examples, such as Figure 12 As shown, the light-emitting device layer 2 includes an anode layer 21, a first auxiliary layer 22, a first light-emitting layer 23, a second auxiliary layer 24, a plurality of second light-emitting layers 25, a third auxiliary layer 26 and a cathode layer 27 provided on the backplane 1. A microcavity A is formed between the anode layer 21 and the cathode layer 27.

[0355] In some examples, the plurality of second light emitting layers 25 include a plurality of second blue light emitting layers 25B, a plurality of second red light emitting layers 25R, and a plurality of second green light emitting layers 25G.

[0356] The first auxiliary layer includes a film layers stacked sequentially, the second auxiliary layer includes b film layers stacked sequentially, and the third auxiliary layer includes c film layers stacked sequentially, where a, b, and c are all positive integers.

[0357] The optical thickness of the a film layer, the optical thickness of the b film layer, and the optical thickness of the c film layer satisfy the formula:

[0358]

[0359] is the average refractive index of the film between the anode layer 21 and the cathode layer 27, The range of r is 1.7~2.0. h is the thickness of the hth film layer among the a film layers mentioned above; r i is the thickness of the i-th film layer among the b film layers mentioned above; r j is the thickness of the jth film layer among the above c film layers.

[0360] For example, The value of can be, for example, 0.7, 0.83, 0.9, 1.1 or 1.3.

[0361] It should be noted that the above average refractive index is: the sum of the optical thicknesses of the film layers between the anode layer 21 and the cathode layer 27 divided by the sum of the actual thicknesses of the film layers between the anode layer 21 and the cathode layer 27. Alternatively, the above average refractive index of the film layers between the anode layer 21 and the cathode layer 27 can be directly measured using a refractive index testing device (such as a refractometer or an ellipsometer).

[0362] For example, The value of can be, for example, 1.7, 1.75, 1.8, 1.9 or 2.0.

[0363] In some examples, in the display substrate 100 provided in the above embodiments, the difference in refractive index between any two of the film layers between the anode layer 21 and the cathode layer 27 is less than or equal to 0.32. This configuration can make the refractive indices of any two of the film layers between the anode layer 21 and the cathode layer 27 closer, thereby reducing the difference in refractive index between any two of the film layers between the anode layer 21 and the cathode layer 27. This can reduce the refractive index jumps between the film layers, ensure good light extraction efficiency for the light-emitting device 2a, and reduce the dispersion of light emitted by the light-emitting device 2a.

[0364] It should be noted that the structure of the display substrate 100 in this embodiment is the same as the structure of the display substrate 100 in some of the above embodiments. Optionally, the backplane 1 in this embodiment has the same features as the backplane 1 in some of the above embodiments, and the light-emitting device layer 2 in this embodiment has the same features as the light-emitting device layer 2 in some of the above embodiments. For details, please refer to the description above and will not be repeated here.

[0365] Some other embodiments of the present disclosure further provide a display substrate 100, such as Figure 13 As shown, the display substrate 100 includes: a back plate 1 and a light emitting device layer 2 .

[0366] In some examples, such as Figure 13 As shown, the light-emitting device layer 2 includes an anode layer 21, a first auxiliary layer 22, a first light-emitting layer 23, a second auxiliary layer 24, a plurality of second light-emitting layers 25, a third auxiliary layer 26 and a cathode layer 27 provided on the backplane 1. A microcavity A is formed between the anode layer 21 and the cathode layer 27.

[0367] In some examples, the second auxiliary layer 24 includes a charge generation layer 247 .

[0368] Exemplarily, the charge generation layer 247 may include an N-type charge generation layer (N-CGL) and a P-type charge generation layer (P-CGL).

[0369] In some examples, the first light emitting layer 23 can emit light of at least two different colors.

[0370] For example, the first light emitting layer 23 may emit red light and blue light, or the first light emitting layer 23 may emit green light and blue light, or the first light emitting layer 23 may emit red light, green light, and blue light.

[0371] Because the first light-emitting layer 23 has two different colors, it needs to be prepared and formed in different processes, wherein each color of the first light-emitting layer 23 can be formed in one process. For example, if the first light-emitting layer 23 is formed using an evaporation process, the first light-emitting layer 23 of one color can be formed in one process, and then the first light-emitting layer 23 of the other color can be formed in another process.

[0372] In some examples, the plurality of second light emitting layers 25 include a plurality of second blue light emitting layers 25B, a plurality of second red light emitting layers 25R, and a plurality of second green light emitting layers 25G.

[0373] The first auxiliary layer 22 includes a film layers stacked sequentially, the second auxiliary layer 24 includes b film layers stacked sequentially, and the third auxiliary layer 26 includes c film layers stacked sequentially, where a, b, and c are all positive integers.

[0374] The optical thickness of the a film layer, the optical thickness of the b film layer, and the optical thickness of the c film layer satisfy the formula:

[0375]

[0376] is the average refractive index of the film between the anode layer and the cathode layer, The range is 1.7~2.0; r h is the thickness of the hth film layer among the a film layers, r i is the thickness of the i-th film layer among the b film layers, r j is the thickness of the jth film layer among the c film layers.

[0377] For example, The value of can be, for example, 0.7, 0.83, 0.9, 1.1 or 1.3.

[0378] It should be noted that the above average refractive index is: the sum of the optical thicknesses of the film layers between the anode layer 21 and the cathode layer 27 divided by the sum of the actual thicknesses of the film layers between the anode layer 21 and the cathode layer 27. Alternatively, the above average refractive index of the film layers between the anode layer 21 and the cathode layer 27 can be directly measured using a refractive index testing device (such as a refractometer or an ellipsometer).

[0379] For example, The value of can be, for example, 1.7, 1.75, 1.8, 1.9 or 2.0.

[0380] In some examples, in the display substrate 100 provided in the above embodiments, the difference in refractive index between any two of the film layers between the anode layer 21 and the cathode layer 27 is less than or equal to 0.32. This configuration can make the refractive indices of any two of the film layers between the anode layer 21 and the cathode layer 27 closer, thereby reducing the difference in refractive index between any two of the film layers between the anode layer 21 and the cathode layer 27. This can reduce the refractive index jumps between the film layers, ensure good light extraction efficiency for the light-emitting device 2a, and reduce the dispersion of light emitted by the light-emitting device 2a.

[0381] It should be noted that the structure of the display substrate 100 in this embodiment is the same as the structure of the display substrate 100 in some of the above embodiments. Optionally, the backplane 1 in this embodiment has the same features as the backplane 1 in some of the above embodiments, and the light-emitting device layer 2 in this embodiment has the same features as the light-emitting device layer 2 in some of the above embodiments. For details, please refer to the description above and will not be repeated here.

[0382] In some examples, in the display substrate 100 provided in the above embodiments, the material types of the film layers between the anode layer 21 and the cathode layer 27 and the refractive index of each film layer to blue light with a wavelength of 460 nm are shown in Table 10 below.

[0383] Table 10

[0384] Film layer name Material Type Refractive index hole injection layer Carbazole-doped radialene 1.74 First hole transport layer Carbazoles 1.74 electron blocking layer Carbazoles 1.87 First hole blocking layer Triazines 1.88 First electron transport layer Triazines 2.00 first charge generation layer Phosphorus oxides 1.82 Second charge generation layer Carbazole-doped radialene 1.74 Second hole transport layer Carbazoles 1.74 Various sub-microcavity adjustment layers Carbazoles 1.87 Second hole blocking layer Triazines 1.86 Second electron transport layer Triazines 1.79 electron injection layer Metal complexes 1.68

[0385] As shown in Table 10, the difference in refractive index between any two of the film layers located between the anode layer 21 and the cathode layer 27 is less than or equal to 0.32. This means that the refractive indices of any two of the film layers located between the anode layer 21 and the cathode layer 27 are closer. By selecting the materials and refractive indices of the film layers located between the anode layer 21 and the cathode layer 27, the difference in refractive index between any two of the film layers located between the anode layer 21 and the cathode layer 27 can be further reduced, and the refractive index jumps between the film layers can be further reduced, thereby achieving good light extraction efficiency for the light-emitting device 2a and reducing the dispersion of the light emitted by the light-emitting device 2a.

[0386] The above description is merely a specific embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that a person skilled in the art can conceive within the technical scope disclosed in the present disclosure should be included within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A display substrate, comprising: a backplane comprising a substrate and a plurality of pixel driving circuits disposed on the substrate; The pixel driving circuit includes a plurality of transistors and at least one storage capacitor; An anode layer, a first auxiliary layer, a second auxiliary layer, a third auxiliary layer and a cathode layer are sequentially stacked on the back plate; a microcavity is formed between the anode layer and the cathode layer; a first light-emitting layer disposed between the first auxiliary layer and the second auxiliary layer; and a plurality of second light-emitting layers of at least two different colors disposed between the second auxiliary layer and the third auxiliary layer; The first auxiliary layer includes a number of film layers stacked sequentially, the second auxiliary layer includes b number of film layers stacked sequentially, and the third auxiliary layer includes c number of film layers stacked sequentially, where a, b, and c are all positive integers. The optical thickness of the a film layer, the optical thickness of the b film layer, and the optical thickness of the c film layer satisfy the formula: is the average refractive index of the film between the anode layer and the cathode layer, The range is 1.7 to 2.0; r h is the thickness of the hth film layer among the a film layers; r i is the thickness of the i-th film layer among the b film layers; r j is the thickness of the jth film layer among the c film layers.

2. The display substrate according to claim 1, wherein The plurality of second light-emitting layers include: a plurality of second blue light-emitting layers, a plurality of second red light-emitting layers and a plurality of second green light-emitting layers; The wavelength of light emitted by the first light-emitting layer is smaller than the wavelength of light emitted by the second light-emitting layer of at least one color.

3. The display substrate according to claim 2, wherein: The first light-emitting layer includes a first guest material, and the second light-emitting layer includes a second guest material; The emission spectrum of the first guest material at least partially overlaps with the absorption spectrum of the second guest material of the second light-emitting layer of at least one color.

4. The display substrate according to claim 3, wherein: An overlapping range between the emission spectrum of the first guest material and the absorption spectrum of the second guest material is greater than or equal to 60% of a wavelength range of the emission spectrum of the first guest material.

5. The display substrate according to claim 3, wherein: An overlapping range between the emission spectrum of the first guest material and the absorption spectrum of the second guest material is greater than or equal to 60% of a wavelength range of the absorption spectrum of the second guest material.

6. The display substrate according to claim 3, wherein: The peak of the emission spectrum of the first guest material is less than 600 nm.

7. The display substrate according to claim 3, wherein: The first guest material includes at least one luminescent material; In the case where the first guest material includes two light-emitting materials, a distance between emission spectrum peaks of the two light-emitting materials is less than or equal to 30 nm.

8. The display substrate according to claim 3, wherein: The peak value of the emission spectrum of the first guest material is in the range of 465 nm to 475 nm, and the peak value of the absorption spectrum of the second guest material of the second green light-emitting layer is in the range of 507 nm to 517 nm.

9. The display substrate according to claim 3, wherein: The peak emission spectrum of the first guest material is in the range of 525nm to 535nm, the peak absorption spectrum of the second guest material of the second green light-emitting layer is in the range of 510nm to 520nm, and the peak absorption spectrum of the second guest material of the second red light-emitting layer is in the range of 595nm to 605nm.

10. The display substrate according to claim 3, wherein: The first guest material includes at least one luminescent material; In the case where the first guest material includes two light-emitting materials, at least one of the two light-emitting materials is doped with boron.

11. The display substrate according to claim 3, wherein: the second guest material of the second light-emitting layer of at least one color comprises at least one light-emitting material; In the case where the second guest material includes two light-emitting materials, a distance between emission spectrum peaks of the two light-emitting materials is less than or equal to 30 nm.

12. The display substrate according to claim 3, wherein: the second guest material of the second light-emitting layer of at least one color comprises at least one light-emitting material; In the case where the second guest material includes two light-emitting materials, at least one of the two light-emitting materials is doped with boron.

13. The display substrate according to claim 11 or 12, wherein: The first guest material includes: at least one of a fluorescent material, a phosphorescent material and a thermally activated delayed fluorescent material; and / or the second guest material includes: at least one of a fluorescent material, a phosphorescent material and a thermally activated delayed fluorescent material with multiple resonance characteristics.

14. The display substrate according to claim 3, wherein: The first light-emitting layer further includes a first host material, and the first host material includes a single host material or a PN mixed host material.

15. The display substrate according to claim 3, wherein: The second light-emitting layer material of at least one color further includes a second host material, and the second host material includes a bipolar host material.

16. The display substrate according to claim 15, wherein: The second host material includes a single host material or a PN mixed host material; In the case where the second host material is a PN mixed-type host material, the N-type material has a thermally activated delayed fluorescence characteristic.

17. The display substrate according to any one of claims 2 to 12 and claims 14 to 16, wherein: The microcavity includes a plurality of sub-microcavities, wherein the plurality of sub-microcavities include a red sub-microcavity corresponding to the second red light-emitting layer, a green sub-microcavity corresponding to the second green light-emitting layer, and a blue sub-microcavity corresponding to the second blue light-emitting layer; The number of film layers located between the anode layer and the cathode layer and corresponding to the sub-microcavity of any color is d, and the optical thickness of the d film layers is L, where L satisfies: Where d is a positive integer, n m is the refractive index of the mth film layer among the d film layers, r m is the thickness of the mth film layer, k is a natural number, λ is the target spectrum peak wavelength, is the phase shift caused by the target light after being reflected from the anode layer.

18. The display substrate according to claim 17, wherein: The length of the blue sub-microcavity is smaller than the length of the red sub-microcavity; The length of the blue sub-microcavity is smaller than the length of the green sub-microcavity.

19. The display substrate according to any one of claims 1 to 12, 14 to 16, and 18, wherein the thickness of the first light-emitting layer is in the range of 15 nm to 60 nm; and / or The thickness of the second light-emitting layer is in the range of 10 nm to 50 nm.

20. The display substrate according to any one of claims 2 to 12, 14 to 16, and 18, wherein The first auxiliary layer includes a light-transmitting conductive layer, a hole injection layer, a first hole transport layer and an electron blocking layer; and / or, The second auxiliary layer includes a first hole blocking layer, a first electron transport layer, a first charge generation layer, a second charge generation layer and a microcavity adjustment layer; and / or, The third auxiliary layer includes a second hole blocking layer, a second electron transport layer and an electron injection layer.

21. The display substrate according to claim 20, wherein: The microcavity adjustment layer includes: a second hole transport layer; a red sub-microcavity adjustment layer disposed between the second hole transport layer and the second red light-emitting layer; a green sub-microcavity adjustment layer disposed between the second hole transport layer and the second green light-emitting layer; and a blue sub-microcavity adjustment layer disposed between the second hole transport layer and the second blue light-emitting layer; The red sub-microcavity adjustment layer and the blue sub-microcavity adjustment layer have different lengths, and the green sub-microcavity adjustment layer and the blue sub-microcavity adjustment layer have different lengths.

22. The display substrate according to claim 21, wherein The red sub-microcavity adjustment layer includes a red hole transport layer and a red electron blocking layer stacked in sequence in a direction away from the back plate, and the green sub-microcavity adjustment layer includes a green hole transport layer and a green electron blocking layer stacked in sequence in a direction away from the back plate; Among them, the red hole transport layer and the green hole transport layer are respectively used to adjust the length of the corresponding color sub-microcavity.

23. The display substrate according to claim 20, wherein: The thickness of the light-transmitting conductive layer is less than or equal to 10 nm; and / or, The thickness of the hole injection layer is less than or equal to 10 nm; and / or, The thickness of the electron blocking layer is less than or equal to 10 nm; and / or, The thickness of the first hole blocking layer is less than or equal to 10 nm; and / or, The thickness of the first electron transport layer is in the range of 15 nm to 50 nm; and / or, The thickness of the first charge generation layer is less than or equal to 10 nm; and / or, The thickness of the second charge generation layer is less than or equal to 10 nm; and / or, The thickness of the second hole blocking layer is less than or equal to 10 nm; and / or, The thickness of the second electron transport layer is in the range of 15 nm to 50 nm.

24. The display substrate according to any one of claims 1 to 12, 14 to 16, 18, and 21 to 23, wherein: There are multiple first light-emitting layers, and the second auxiliary layer is disposed between any two adjacent first light-emitting layers; and / or, The plurality of second light-emitting layers are located in the same layer and constitute a light-emitting layer group. There are a plurality of light-emitting layer groups, and the third auxiliary layer is disposed between any two adjacent light-emitting layer groups.

25. The display substrate according to claim 1, wherein The second auxiliary layer includes a charge generation layer; The first light-emitting layer can emit at least two different colors of light; The plurality of second light emitting layers include a plurality of second blue light emitting layers, a plurality of second red light emitting layers, and a plurality of second green light emitting layers.

26. The display substrate according to any one of claims 1 to 12, 14 to 16, 18, 21 to 23, and 25, wherein: The substrate is a flexible substrate.

27. The display substrate according to any one of claims 1 to 12, 14 to 16, 18, 21 to 23, and 25, wherein: The anode layer includes: a reflective layer; or The anode layer includes a reflective layer and a light-transmitting layer located on a side of the reflective layer close to the back plate.

28. The display substrate according to any one of claims 1 to 12, 14 to 16, 18, 21 to 23, and 25, wherein: The thickness of the cathode layer ranges from 10 nm to 20 nm.

29. The display substrate according to any one of claims 1 to 12, 14 to 16, 18, 21 to 23, and 25, further comprising: An optical cover layer and / or an encapsulation layer are sequentially stacked on the cathode layer.

30. The display substrate according to claim 29, wherein In the case where the display substrate includes an encapsulation layer, a type of the encapsulation layer includes thin film encapsulation.

31. The display substrate according to any one of claims 2 to 12, 14 to 16, 18, 21 to 23, 25, and 30, wherein: The second red light emitting layer can emit red light, and the wavelength of the red light is in the range of 615nm to 630nm; The second green light emitting layer can emit green light, and the wavelength of the green light is in the range of 515nm to 535nm; The second blue light emitting layer can emit blue light, and the wavelength of the blue light is in the range of 460nm to 475nm.

32. A display device comprising: The display substrate according to any one of claims 1 to 31.

33. The display device according to claim 32, further comprising: frame; the display substrate is arranged in the frame; circuit boards; and, Data driver integrated circuit.

Images