Display substrate and display device

Abstract

The display substrate (100) comprises a back plate (1), an anode layer (21), a first auxiliary layer (22), a plurality of first light-emitting layers (23), a second auxiliary layer (24), a plurality of second light-emitting layers (25), a third auxiliary layer (26) and a cathode layer (27), the first auxiliary layer (22), the second auxiliary layer (24) and the third auxiliary layer (26) are arranged to enable the first light-emitting layers and the second light-emitting layers to form a series light-emitting device, and the light-emitting brightness is increased. # imgabs0 #

Description

Display substrate and display device

[0001] This application claims priority to Chinese patent application No. 202210798479.2, filed on July 8, 2022, the entire contents of which are incorporated herein by reference. 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] Organic Light Emitting Diode (OLED) display technology utilizes luminescent materials driven by an electric current to create a display. OLED displays offer advantages such as ultra-lightness, ultra-thinness, high brightness, wide viewing angles, low voltage, low power consumption, fast response, high definition, shock resistance, flexibility, low cost, simple manufacturing, minimal use of raw materials, high luminous efficiency, and a wide temperature range.

[0004] Summary of the Invention

[0005] 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.

[0006] To achieve the above objectives, the embodiments of the present disclosure provide the following technical solutions:

[0007] On the one hand, a display substrate is provided. The display substrate includes: a backplane, an anode layer, a first auxiliary layer, a second auxiliary layer, a third auxiliary layer and a cathode layer stacked in sequence on the backplane, a plurality of first light-emitting layers of at least two different colors arranged between the first auxiliary layer and the second auxiliary layer, and a plurality of second light-emitting layers of at least two different colors arranged between the second auxiliary layer and the third auxiliary layer. A microcavity is formed between the anode layer and the cathode layer. The plurality of first light-emitting layers include at least a plurality of first blue light-emitting layers. The plurality of second light-emitting layers include at least a plurality of second blue light-emitting layers. The first auxiliary layer includes a number of film layers stacked in sequence, and the optical thickness of the portion of the a number of film layers opposite to the first blue light-emitting layer is L1, and L1 satisfies:

[0008]

[0009] a is a positive integer, n h is the refractive index of the hth film layer among the a film layers, r h is the thickness of the hth film layer.

[0010] The third auxiliary layer includes b layers stacked in sequence, and the optical thickness of the portion of the b layers facing the first blue light-emitting layer is L2, and L2 satisfies:

[0011]

[0012] b is a positive integer, n i is the refractive index of the i-th film layer among the b film layers, r i is the thickness of the i-th film layer.

[0013] L1 and L2 satisfy the formula:

[0014]

[0015] is the average refractive index of the layer located between the first auxiliary layer and the third auxiliary layer and opposite to the first blue light-emitting layer to the central wavelength of blue light, λ B is the peak wavelength of the blue light target spectrum, and k is a positive integer.

[0016] The display substrate provided by 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 layer included in the first auxiliary layer L1 and the optical thickness of the b film layer included in the third auxiliary layer L2 satisfy the formula:

[0017]

[0018] 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.

[0019] In some embodiments, the plurality of first light-emitting layers further include a plurality of first red light-emitting layers and a plurality of first green light-emitting layers, wherein the first red light-emitting layers and the first blue light-emitting layers have different thicknesses, and / or the first green light-emitting layers and the first blue light-emitting layers have different thicknesses.

[0020] In some embodiments, the plurality of second light-emitting layers further include a plurality of second red light-emitting layers and a plurality of second green light-emitting layers. The second red light-emitting layers and the second blue light-emitting layers have different thicknesses, and / or the second green light-emitting layers and the second blue light-emitting layers have different thicknesses.

[0021] In some embodiments, the second auxiliary layer includes a first microcavity adjustment layer, wherein a portion of the first microcavity adjustment layer opposite the second red light-emitting layer has a different thickness than a portion of the first microcavity adjustment layer opposite the second blue light-emitting layer, and / or a portion of the first microcavity adjustment layer opposite the second green light-emitting layer has a different thickness than a portion of the first microcavity adjustment layer opposite the second blue light-emitting layer.

[0022] In some embodiments, the first microcavity adjustment layer includes: a second hole transport layer, a first red sub-microcavity adjustment layer, a first green sub-microcavity adjustment layer, and a first blue sub-microcavity adjustment layer. The first red sub-microcavity adjustment layer is disposed between the second hole transport layer and the second red light-emitting layer, the first green sub-microcavity adjustment layer is disposed between the second hole transport layer and the second green light-emitting layer, and the first blue sub-microcavity adjustment layer is disposed between the second hole transport layer and the second blue light-emitting layer. The first red sub-microcavity adjustment layer and the first blue sub-microcavity adjustment layer have different thicknesses, and / or the first green sub-microcavity adjustment layer and the first blue sub-microcavity adjustment layer have different thicknesses.

[0023] In some embodiments, the first 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 backplate, and the first 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 backplate. The red hole transport layer and the green hole transport layer are each used to adjust the microcavity length.

[0024] In some embodiments, the wavelength of light emitted by the first light-emitting layer of at least one color is shorter than the wavelength of light emitted by the second light-emitting layer of the corresponding color.

[0025] 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 of at least one color of the first light-emitting layer at least partially overlaps with the absorption spectrum of the second guest material of the corresponding color of the second light-emitting layer.

[0026] 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.

[0027] 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.

[0028] In some embodiments, the peak emission spectrum of the first guest material of the first red light-emitting layer is in the range of 560 nm to 570 nm, and the peak absorption spectrum of the second guest material of the second red light-emitting layer is in the range of 595 nm to 605 nm.

[0029] In some embodiments, the peak emission spectrum of the first guest material of the first green light-emitting layer is in the range of 500 nm to 510 nm, and the peak absorption spectrum of the second guest material of the second green light-emitting layer is in the range of 515 nm to 525 nm.

[0030] In some embodiments, the first guest material of the first light-emitting layer of at least one color includes at least one light-emitting material. In the case where the first 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.

[0031] In some embodiments, the first guest material includes two luminescent materials, at least one of which is doped with boron, and the doping ratio of the boron is in a range of 0.5% to 5%.

[0032] In some embodiments, the second guest material of the at least one color 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.

[0033] In some embodiments, the second guest material includes two luminescent materials, at least one of which is doped with boron, and the doping ratio of the boron is in a range of 0.5% to 5%.

[0034] 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 and a thermally activated delayed fluorescent material with multiple resonance characteristics.

[0035] In some embodiments, the first light-emitting layer further includes a first host material, which is a single host material or a PN mixed host material. The second light-emitting layer further includes a second host material, which includes a bipolar host material.

[0036] In some embodiments, the second host material is 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 host material of the N-type component has thermally activated delayed fluorescence characteristics.

[0037] In some embodiments, the first red light-emitting layer and the second red light-emitting layer are oppositely arranged, the first green light-emitting layer and the second green light-emitting layer are oppositely arranged, and the first blue light-emitting layer and the second blue light-emitting layer are oppositely arranged.

[0038] In some embodiments, the first auxiliary layer includes: a light-transmitting conductive layer, a hole injection layer, and a second microcavity adjustment layer stacked in sequence in a direction away from the backplane. The second microcavity adjustment layer includes: a first hole transport layer, a second red microcavity adjustment layer disposed between the first hole transport layer and the first red light-emitting layer, a second green microcavity adjustment layer disposed between the first hole transport layer and the first green light-emitting layer, and a second blue microcavity adjustment layer disposed between the first hole transport layer and the first blue light-emitting layer.

[0039] In some embodiments, the first auxiliary layer includes a light-transmitting conductive layer, a hole injection layer, and a second microcavity adjustment layer stacked in sequence in a direction away from the back plate. The second microcavity adjustment layer includes a first hole transport layer and an electron blocking layer.

[0040] In some embodiments, the first auxiliary layer includes: a light-transmitting conductive layer, a hole injection layer, and a second microcavity adjustment layer stacked in sequence in a direction away from the backplane. The second microcavity adjustment layer includes: a first hole transport layer, a second blue sub-microcavity adjustment layer disposed on a side of the first hole transport layer away from the backplane, a second red sub-microcavity adjustment layer disposed between the second blue sub-microcavity adjustment layer and the first red light-emitting layer, and a second green sub-microcavity adjustment layer disposed between the second blue sub-microcavity adjustment layer and the first green light-emitting layer.

[0041] In some embodiments, the microcavity includes a plurality of sub-microcavities, including a red sub-microcavity corresponding to the first red light-emitting layer, a green sub-microcavity corresponding to the first green light-emitting layer, and a blue sub-microcavity corresponding to the first blue light-emitting layer. The number of film layers located between the anode layer and the cathode layer and corresponding to the sub-microcavities of any color is c, and the optical thickness of the c film layers is L3, where L3 satisfies:

[0042]

[0043] c is a positive integer, n j is the refractive index of the jth film layer among the c film layers, r jis the thickness of the j-th film layer.

[0044] The sub-microcavity of any color satisfies:

[0045]

[0046] m is a natural number, λ is the interference wavelength, is the phase shift caused by the anode layer.

[0047] 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.

[0048] In some embodiments, the anode layer includes: an anode layer and a light-transmitting conductive layer stacked in sequence in a direction away from the back plate; the optical thickness of the portion of the anode layer opposite to the first blue light-emitting layer is the optical thickness of the portion of the light-transmitting conductive layer opposite to the first blue light-emitting layer.

[0049] In some embodiments, the second auxiliary layer further includes: a first hole blocking layer, a first electron transport layer, and a charge generation layer, which are located on a side of the first microcavity adjustment layer close to the backplate and are stacked in sequence in a direction away from the backplate; and / or, the third auxiliary layer includes: a second hole blocking layer, a second electron transport layer, and an electron injection layer, which are stacked in sequence in a direction away from the backplate.

[0050] In some embodiments, 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 generating layer is less than or equal to 10 nm; and / or the thickness of the second charge generating 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.

[0051] In some embodiments, the thickness of the first blue light-emitting layer ranges from 15 nm to 60 nm; and / or the thickness of the second blue light-emitting layer ranges from 10 nm to 50 nm.

[0052] In some embodiments, there are multiple second auxiliary layers, and multiple first light-emitting layers of at least two different colors or multiple second light-emitting layers of at least two different colors are disposed between any two adjacent second auxiliary layers.

[0053] In another aspect, a display device is provided, comprising: a display substrate as described in any one of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] 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 should be considered schematic diagrams and are not intended to limit the actual dimensions, etc., of the products involved in the embodiments of the present disclosure.

[0055] FIG1 is a structural diagram of a display device according to some embodiments of the present disclosure;

[0056] FIG2 is a structural diagram of a display substrate according to some embodiments of the present disclosure;

[0057] FIG3 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0058] FIG4 is a structural diagram of a display substrate in the first embodiment;

[0059] FIG5 is a structural diagram of a display substrate in the second embodiment;

[0060] FIG6 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0061] FIG7 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0062] FIG8 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0063] FIG9 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0064] FIG10 is a structural diagram of another display substrate according to some embodiments of the present disclosure;

[0065] FIG11 is a spectrum diagram of a portion of the light-emitting layer in Verification Example 1;

[0066] FIG12 is a spectrum diagram of another portion of the light-emitting layer in Verification Example 1;

[0067] FIG13 is a spectrum diagram of the blue light-emitting device in Verification Example 2. DETAILED DESCRIPTION

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] “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.

[0073] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0074] As used herein, the term "if" is optionally interpreted to mean "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined that" or "if [stated condition or event] is detected" are optionally interpreted to mean "upon determining" or "in response to determining" or "upon detecting [stated condition or event]" or "in response to detecting [stated condition or event]," depending on the context.

[0075] The use of "adapted to" or "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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] As shown in FIG1 , 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 graphic. 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), and the like.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] In some embodiments, as shown in FIG. 2 , the display substrate 100 includes: a back plate 1 .

[0085] In some examples, the backplane 1 includes a substrate 11 and a plurality of pixel driving circuits 12 disposed on the substrate 11 .

[0086] There are many types of the substrate 11, which can be selected according to actual needs.

[0087] For example, the substrate 11 may be a rigid substrate, the material of which may include glass, quartz, or plastic.

[0088] For example, the substrate 11 may be a flexible substrate. The material of the flexible substrate may include PET (Polyethylene terephthalate), PEN (Polyethylene naphthalate two formic acid glycol ester), or PI (Polyimide).

[0089] In some examples, the plurality of pixel driving circuits 12 are arranged in an array, for example.

[0090] 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.

[0091] Exemplarily, FIG. 3 uses a transistor 121 to represent the pixel driving circuit 12 .

[0092] In some embodiments, as shown in FIG3 , the display substrate 100 further includes a light-emitting device layer 2 .

[0093] In some examples, the light emitting device layer 2 includes a plurality of light emitting devices 2a, which are arranged in an array, for example, and the light emitting devices 2a are, for example, OLEDs.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] Here, each pixel driving circuit 12 and the light emitting device 2a electrically connected thereto may be referred to as a sub-pixel.

[0099] 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.

[0100] 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.

[0101] In another implementation, there are two main ways to provide a full-color solution through color conversion or color filtering.

[0102] As shown in Figure 4, in the first embodiment, the first light-emitting device 2a' is a series-connected bottom-emitting light-emitting device, and the first light-emitting device 2a' is configured to emit white light. The display substrate further includes a color filter CF disposed on the side of the first substrate 11' away from the first light-emitting device 2a'. The white light emitted by the first light-emitting device 2a' is converted into red, green, or blue light after passing through the color filter CF, thereby achieving a full-color display. However, the structure of the bottom-emitting light-emitting device also makes it difficult to increase the brightness at a normal viewing angle. In addition, if a top-emitting light-emitting device is used, the process complexity will increase and the light loss in certain bands will be excessive.

[0103] As shown in Figure 5, in the second embodiment, the first 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 the first light-emitting device 2a' facing away from the first 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 the first 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 the first substrate 11', to improve color purity. This increases the display substrate's manufacturing complexity and power consumption.

[0104] Based on this, as shown in Figure 3, in some embodiments of the present disclosure, the light-emitting device layer 2 includes an anode layer 21, a first auxiliary layer 22, multiple first light-emitting layers 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.

[0105] In some examples, as shown in FIG3 , 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 2 a , and each light-emitting device 2 a 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 2 a.

[0106] 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.

[0107] For example, when the anode layer 21 is a single-layer structure, the single-layer structure has a good light reflection performance and can reflect the light directed toward the anode layer 21 .

[0108] For example, when the anode layer 21 is a structure in which multiple layers are stacked in sequence, the layer farther from the backplane 1 within the multilayer layer is a layer with good light reflectivity, capable of reflecting light directed toward the anode layer 21. The material of the layer with good light reflectivity may, for example, include at least one of Al (aluminum), Ag (silver), or Mg (magnesium). The layer closer to the backplane 1 within the multilayer layer may, for example, be a layer with good light transmittance. The material of the layer with good light transmittance may, for example, include ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide).

[0109] 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.

[0110] 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.

[0111] In some examples, as shown in FIG3 , the first auxiliary layer 22 is disposed on a side of the anode layer 21 away from the substrate 11 . Alternatively, the first auxiliary layer 22 is located on a side of the pixel defining layer away from the substrate 11 .

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] For example, the present disclosure may form the first auxiliary layer 22 by using an evaporation process.

[0117] 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 .

[0118] In some examples, as shown in FIG3 , the multiple first light-emitting layers 23 are disposed on a side of the first auxiliary layer 22 away from the substrate 11 . For example, the multiple first light-emitting layers 23 can be located on the same layer, with each first light-emitting layer 23 in contact with the first auxiliary layer 22 to form an electrical connection. Of course, at least two first light-emitting layers 23 can also be stacked. This disclosure uses the example of multiple first light-emitting layers 23 being located on the same layer.

[0119] Illustratively, the plurality of first light-emitting layers 23 are arranged in one-to-one correspondence with the plurality of anodes 211 in the anode layer 21. Each first light-emitting layer 23 faces the corresponding anode 211, that is, their orthographic projections on the substrate 11 partially overlap or coincide.

[0120] Illustratively, the plurality of first light-emitting layers 23 have at least two different colors and include at least a plurality of first blue light-emitting layers 23B.

[0121] For example, the plurality of first light-emitting layers 23 may have two different colors. Alternatively, the plurality of first light-emitting layers 23 may include a plurality of first blue light-emitting layers 23B and a plurality of first red light-emitting layers 23R. Alternatively, the plurality of first light-emitting layers 23 may include a plurality of first blue light-emitting layers 23B and a plurality of first green light-emitting layers 23G.

[0122] For another example, the plurality of first light-emitting layers 23 have three different colors. Optionally, the plurality of first light-emitting layers 23 include a plurality of first blue light-emitting layers 23B, a plurality of first red light-emitting layers 23R, and a plurality of first green light-emitting layers 23G.

[0123] Because the multiple first light-emitting layers 23 have two different colors, they need to be prepared and formed in different processes, where each color of the first light-emitting layers 23 can be formed in one process. For example, if the multiple first light-emitting layers 23 are formed using an evaporation process, the first light-emitting layers 23 of one color can be formed in one process, and then the first light-emitting layers 23 of the other color can be formed in another process.

[0124] It should be noted that the above-mentioned first auxiliary layer 22 is located between the anode layer 21 and the multiple first light-emitting layers 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.

[0125] In some examples, as shown in FIG3 , the second auxiliary layer 24 is disposed on a side of the plurality of first light-emitting layers 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 is in contact with each first light-emitting layer 23 to form an electrical connection.

[0126] Illustratively, the second auxiliary layer 24 includes a plurality of film layers stacked in sequence, and different light-emitting devices 2 a share the second auxiliary layer 24 .

[0127] For example, the present disclosure may form the second auxiliary layer 24 by using an evaporation process.

[0128] 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 first auxiliary layer 22 and the display substrate 100 .

[0129] In some examples, as shown in FIG3 , 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.

[0130] Exemplarily, the plurality of second light-emitting layers 25 are disposed in a one-to-one correspondence with the plurality of first light-emitting layers 23. Each second light-emitting layer 25 is opposite to a corresponding first light-emitting layer 23, that is, their orthographic projections on the substrate 11 partially overlap or coincide with each other. Furthermore, the orthographic projections of each second light-emitting layer 25 and the corresponding anode 211 on the substrate 11 partially overlap or coincide with each other.

[0131] Illustratively, the plurality of second light-emitting layers 25 have at least two different colors and include at least a plurality of second blue light-emitting layers 25B.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] In some examples, as shown in FIG3 , 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 is in contact with each of the second light-emitting layers 25 to form an electrical connection.

[0137] Exemplarily, the third auxiliary layer 26 includes b film layers stacked in sequence, where b is a positive integer. For example, the number of film layers included in the third auxiliary layer 26 is one, two, or three.

[0138] Optionally, different light-emitting devices 2 a share the third auxiliary layer 26 .

[0139] For example, the present disclosure may form the third auxiliary layer 26 by using an evaporation process.

[0140] 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 .

[0141] In some examples, as shown in FIG. 3 , 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.

[0142] Exemplarily, different light-emitting devices 2a share the cathode layer 27. That is, the cathode layer 27 is a whole layer structure.

[0143] For example, the present disclosure may form the cathode layer 27 using an evaporation process.

[0144] 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 .

[0145] 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.

[0146] 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.

[0147] Exemplarily, the reflectivity of the anode layer 21 is greater than or equal to 80%.

[0148] It is understood that, based on the properties of the anode layer 21 and the cathode layer 27, a microcavity A can be formed between the anode layer 21 and the cathode layer 27, as shown in FIG6 . In this way, light emitted by the first light-emitting layer 23 and the second light-emitting layer 25 can reflect and interfere within the microcavity, generating a microcavity effect, 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 2a. For example, the luminous intensity of blue light can be enhanced and the spectrum of blue light can be narrowed.

[0149] As shown in FIG3 , the optical thickness of the portion of the a film layer in the first auxiliary layer 22 facing the first blue light-emitting layer 23B is L1, and L1 satisfies:

[0150]

[0151] a is a positive integer, n h is the refractive index of the hth film layer among the a films, r h is the thickness of the hth film layer mentioned above.

[0152] The optical thickness of the portion of the b layers in the third auxiliary layer that faces the first blue light-emitting layer 23B is L2, and L2 satisfies:

[0153]

[0154] b is a positive integer, n iis the refractive index of the i-th film layer among the b film layers, r i is the thickness of the i-th film layer.

[0155] L1 and L2 satisfy the formula:

[0156]

[0157] is the average refractive index of the layer located between the first auxiliary layer 22 and the third auxiliary layer 26 and opposite to the first blue light-emitting layer 23B, λ B is the peak wavelength of the blue light target spectrum, and k is a positive integer.

[0158] It should be noted that the aforementioned optical thickness is the refractive index of the target film layer multiplied by the actual thickness of the target film layer. The aforementioned average refractive index is: the sum of the optical thicknesses of the film layers located between the first auxiliary layer 22 and the third auxiliary layer 26 and opposite the first blue light-emitting layer 23B, divided by the sum of the actual thicknesses of the film layers located between the first auxiliary layer 22 and the third auxiliary layer 26 and opposite the first blue light-emitting layer 23B. Here, the average refractive index of the film layers located between the first auxiliary layer 22 and the third auxiliary layer 26 and opposite the first blue light-emitting layer 23B can be directly measured, for example, using a refractive index measuring device (e.g., a refractometer or ellipsometer).

[0159] It should be noted that the film layer opposite to the first blue light-emitting layer 23B is a film layer covering the opening of the pixel defining layer of the blue sub-pixel.

[0160] For example, the film layer located between the first auxiliary layer 22 and the third auxiliary layer 26 and opposite to the first blue light-emitting layer 23B includes the first blue light-emitting layer, the second auxiliary layer, and the second blue light-emitting layer.

[0161] By ensuring that L1 and L2 satisfy the above formula, the luminous efficiency and color purity of the blue light-emitting device 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 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.

[0162] Correspondingly, L1 and L2 in the opposite areas of the first light-emitting layer 23 of other colors satisfy the formula:

[0163]

[0164] In this case, the luminous efficiency and color purity of the light-emitting device of the corresponding color can also be enhanced.

[0165] In some examples, The range is 1.7 to 2.0.

[0166] For example, The value of can be, for example, 1.7, 1.75, 1.8, 1.9 or 2.0.

[0167] In some embodiments, as shown in FIG3 , the plurality of first light-emitting layers 23 further include a plurality of first red light-emitting layers 23R and a plurality of first green light-emitting layers 23G. The first red light-emitting layers 23R and the first blue light-emitting layers 23B have different thicknesses, and / or the first green light-emitting layers 23G and the first blue light-emitting layers 23B have different thicknesses.

[0168] For example, the plurality of first red light emitting layers 23R, the plurality of first green light emitting layers 23G, and the plurality of first blue light emitting layers 23B can emit light of corresponding colors, so that the display substrate 100 can achieve full-color display.

[0169] For example, by making the thickness of the first red light-emitting layer 23R and the first blue light-emitting layer 23B different, and making the thickness of the first green light-emitting layer 23G and the first blue light-emitting layer 23B different, the length of the microcavity corresponding to the first light-emitting layer 23 of the corresponding color can be adjusted, thereby enhancing the luminous efficiency and color purity of the light-emitting device of the corresponding color.

[0170] In some embodiments, as shown in FIG3 , the plurality of second light-emitting layers 25 further 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 and the second blue light-emitting layers 25B have different thicknesses, and / or the second green light-emitting layers 25G and the second blue light-emitting layers 25B have different thicknesses.

[0171] For example, the plurality of second red light emitting layers 25R, the plurality of second green light emitting layers 25G, and the plurality of second blue light emitting layers 25B can emit light of corresponding colors, so that the display substrate 100 can achieve full-color display.

[0172] For example, by making the thickness of the second red light-emitting layer 25R and the second blue light-emitting layer 25B different, and making the thickness of the second green light-emitting layer 25G and the second blue light-emitting layer 25B different, the length of the microcavity corresponding to the second light-emitting layer 25 of the corresponding color can be adjusted, thereby enhancing the luminous efficiency and color purity of the light-emitting device of the corresponding color.

[0173] For example, the wavelength of light emitted by the first light-emitting layer 23 is smaller than the wavelength of light emitted by the second red light-emitting layer 25R; or, the wavelength of light emitted by the first light-emitting layer 23 is smaller 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 smaller than the wavelength of light emitted by the second red light-emitting layer 25R, and smaller than the wavelength of light emitted by the second green light-emitting layer 25G, although this disclosure is not limited thereto.

[0174] For example, the first light emitting layer 23 can emit blue light or yellow light.

[0175] By ensuring that the wavelength of light emitted by the first light-emitting layer 23 is shorter than the wavelength of light emitted by at least one color of the second light-emitting layer 25, the light emitted by the first light-emitting layer 23, when directed toward the multiple second light-emitting layers 25, can 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. Furthermore, as shown in FIG6 , the light emitted by the first light-emitting layer 23 can be reflected multiple times within the microcavity A, allowing the light emitted by the first light-emitting layer 23 to be directed toward the multiple second light-emitting layers 25 multiple times. This further enhances 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, further increasing the luminance and luminous efficiency of the display substrate 100.

[0176] It should be noted that there are multiple positional relationships between the multiple first red light-emitting layers 23R, the multiple first green light-emitting layers 23G, the multiple first blue light-emitting layers 23B and the multiple second red light-emitting layers 25R, the multiple second green light-emitting layers 25G, and the multiple second blue light-emitting layers 25B, which can be set as needed.

[0177] In some examples, the first light-emitting layer 23 and the second light-emitting layer 25 of the same color are disposed opposite each other, that is, the orthographic projections of the first light-emitting layer 23 and the second light-emitting layer 25 of the same color on the substrate 11 partially overlap or coincide.

[0178] For example, the multiple first blue light-emitting layers 23B are respectively arranged opposite to the multiple second blue light-emitting layers 25B, the multiple first red light-emitting layers 23R are arranged opposite to the multiple second red light-emitting layers 25R, and the multiple first green light-emitting layers 23G are arranged opposite to the multiple second green light-emitting layers 25G.

[0179] By arranging the first light-emitting layer 23 and the second light-emitting layer 25 of the same color opposite to each other, the light-emitting efficiency of the light-emitting device 2a can be improved, and the color purity of the red light, green light or blue light emitted by the light-emitting device 2a can be improved.

[0180] 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.

[0181] 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.

[0182] 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 .

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] In some embodiments, the first guest material of the first light-emitting layer 23 of at least one color includes at least one light-emitting material. In the case where 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.

[0195] Illustratively, the first guest material of the first red light-emitting layer 23R includes at least one light-emitting material; or, the first guest material of the first green light-emitting layer 23G includes at least one light-emitting material; or, the first guest material of the first blue light-emitting layer 23B includes at least one light-emitting material; or, the first guest material of the first red light-emitting layer 23R and the first guest material of the first green light-emitting layer 23G both include at least one light-emitting material; or, other schemes may also be possible, and the present disclosure is not limited to this.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] In some embodiments, the emission spectrum of the first guest material of the first red light-emitting layer 23R overlaps with the absorption spectrum of the second guest material of the second red light-emitting layer 25R.

[0201] Illustratively, the peak value of the emission spectrum of the first guest material is in the range of 560 nm to 570 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 595 nm to 605 nm.

[0202] For example, the peak emission spectrum of the first guest material of the first red light-emitting layer 23R may be 560 nm, 562 nm, 566 nm, 568 nm, or 570 nm, etc. The peak absorption spectrum of the second guest material of the second green light-emitting layer 25G may be 595 nm, 597 nm, 600 nm, 602 nm, or 605 nm, etc.

[0203] This configuration can make the emission spectrum of the first guest material of the first red light-emitting layer 23R and the absorption spectrum of the second guest material of the second red light-emitting layer 25R have a larger overlapping range, thereby improving the luminous efficiency of the second guest material of the second red light-emitting layer 25R.

[0204] In some embodiments, the emission spectrum of the first guest material of the first green light-emitting layer 23G and the absorption spectrum of the second guest material of the second green light-emitting layer 25G have overlap.

[0205] Illustratively, the peak value of the emission spectrum of the first guest material is in the range of 500 nm to 510 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 515 nm to 525 nm.

[0206] For example, the peak emission spectrum of the first guest material may be 500 nm, 502 nm, 506 nm, 508 nm or 510 nm, etc. The peak absorption spectrum of the second guest material of the second green light emitting layer 25G may be 515 nm, 518 nm, 520 nm, 522 nm or 525 nm, etc.

[0207] This configuration can make the emission spectrum of the first guest material of the first green light-emitting layer 23G and the absorption spectrum of the second guest material of the second green light-emitting layer 25G have a larger overlapping range, thereby improving the luminous efficiency of the second guest material of the second green light-emitting layer 25G.

[0208] 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%.

[0209] For example, the doping ratio of boron element can be: 0.5%, 1.5%, 3.5%, 4% or 5%, etc.

[0210] 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.

[0211] 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.

[0212] 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.

[0213] Exemplarily, the first host material includes at least one material selected from the group consisting of anthracene-based materials, fluorene-based materials, pyrene-based materials, and carbazole-based derivative materials.

[0214] In some embodiments, the thickness of the first blue light emitting layer 23B is in the range of 15 nm to 60 nm.

[0215] For example, the thickness of the first blue light emitting layer 23B may be 15 nm, 20 nm, 35 nm, 45 nm, or 60 nm.

[0216] 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.

[0217] 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.

[0218] 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.

[0219] 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.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] In some embodiments, when the second guest material of the second light-emitting layer 25 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%.

[0224] For example, the doping ratio of boron element can be: 0.5%, 1.5%, 3.5%, 4% or 5%, etc.

[0225] 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.

[0226] In some embodiments, the second light emitting layer 25 further includes a second host material. The second host material includes a bipolar host material.

[0227] In some embodiments, the second host material is a single host material or a PN mixed host material.

[0228] 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.

[0229] 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.

[0230] In some embodiments, the second blue light emitting layer 25B has a thickness ranging from 10 nm to 50 nm.

[0231] For example, the thickness of the second light emitting layer 25 can be 10 nm, 20 nm, 28 nm, 38 nm, or 50 nm.

[0232] In some embodiments, as shown in FIG6 , microcavity A includes multiple sub-microcavities A1, including a red sub-microcavity A1-R corresponding to the first red light-emitting layer 23R, a green sub-microcavity A1-G corresponding to the first green light-emitting layer 23G, and a blue sub-microcavity A1-B corresponding to the first blue light-emitting layer 23B. The number of film layers located between the anode layer 21 and the cathode layer 27 and corresponding to any color of sub-microcavity A1 is c, and the optical thickness of the c film layers is L3, where L3 satisfies:

[0233]

[0234] Where c is a positive integer, 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 jth film layer.

[0235] The sub-microcavity A1 of any color satisfies:

[0236]

[0237] m is a natural number, λ is the interference wavelength, is the phase shift caused by the anode layer 21.

[0238] 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.

[0239] Exemplarily, when L3 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.

[0240] 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.

[0241] 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.

[0242] 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, green, and blue light can all produce microcavity effects, the length of the blue sub-microcavity A1-B is the smallest.

[0243] In some embodiments, as shown in FIG6 , the second auxiliary layer 24 includes a first microcavity adjustment layer 241. The thickness of the portion of the first microcavity adjustment layer 241 facing the second red light-emitting layer 25R is different from the thickness of the portion of the first microcavity adjustment layer 241 facing the second blue light-emitting layer 25B, and / or the thickness of the portion of the first microcavity adjustment layer 241 facing the second green light-emitting layer 25G is different from the thickness of the portion of the first microcavity adjustment layer 241 facing the second blue light-emitting layer 25B.

[0244] Exemplarily, the first microcavity adjustment layer 241 is used to adjust the length of the microcavity A. By adjusting the thickness of the portions of the first microcavity adjustment layer 241 that are opposite the second red light-emitting layer 25R, the second green light-emitting layer 25G, and the second blue light-emitting layer 25B, respectively, the corresponding colored light can produce a microcavity effect in the red sub-microcavity A1-R, the green sub-microcavity A1-G, and the blue sub-microcavity A1-B.

[0245] In some embodiments, as shown in FIG6 , the first microcavity adjustment layer 241 includes: a second hole transport layer 2411; a first red sub-microcavity adjustment layer 2412R disposed between the second hole transport layer 2411 and the second red light-emitting layer 25R; a first green sub-microcavity adjustment layer 2412G disposed between the second hole transport layer 2411 and the second green light-emitting layer 25G; and a first blue sub-microcavity adjustment layer 2412B disposed between the second hole transport layer 2411 and the second blue light-emitting layer 25B. The first red sub-microcavity adjustment layer 2412R and the first blue sub-microcavity adjustment layer 2412B have different thicknesses, and the first green sub-microcavity adjustment layer 2412G and the first blue sub-microcavity adjustment layer 2412B have different thicknesses.

[0246] In some examples, the second hole transport layer 2411 is provided as a whole layer and has an adjustable thickness.

[0247] By providing the second hole transport layer 2411 as a whole layer, the manufacturing process of the display substrate 100 can be simplified.

[0248] By adjusting the thickness of the second hole transport layer 2411 , the length of the microcavity A can be adjusted, so that the corresponding color light can produce a microcavity effect in the red sub-microcavity A1-R, the green sub-microcavity A1-G, and the blue sub-microcavity A1-B.

[0249] Illustratively, the second hole transport layer 2411 is used to lower the hole injection barrier and increase 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.

[0250] For example, the HOMO energy level of the material of the second hole transport layer 2411 ranges from -5.2 eV to -5.6 eV. For example, the HOMO energy level of the material of the second hole transport layer 2411 includes: -5.2 eV, -5.3 eV, -5.4 eV, -5.5 eV, -5.6 eV, etc.

[0251] Exemplarily, the T1 of the materials of the first red sub-microcavity adjustment layer 2412R, the first green sub-microcavity adjustment layer 2412G, and the first blue sub-microcavity adjustment layer 2412B is higher than the T1 of the light-emitting material of the second light-emitting layer 25 .

[0252] For example, the T1 of the materials of the first red sub-microcavity adjustment layer 2412R, the first green sub-microcavity adjustment layer 2412G, and the first blue sub-microcavity adjustment layer 2412B is at least 0.2 eV higher than the T1 of the light-emitting material of the second light-emitting layer 25 .

[0253] Exemplarily, the thickness of the first blue sub-microcavity adjustment layer 2412B is less than or equal to 10 nm.

[0254] For example, the thickness of the first blue sub-microcavity adjustment layer 2412B can be 1 nm, 3 nm, 5 nm, 7 nm, or 10 nm.

[0255] 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. As shown in FIG6 , multiple sub-microcavities A1 share the first auxiliary layer 22, the first light-emitting layer 23, a portion of the second auxiliary layer 24, and the third auxiliary layer 26. By varying the thicknesses of the first red sub-microcavity adjustment layer 2412R and the first blue sub-microcavity adjustment layer 2412B, and varying the thicknesses of the first green sub-microcavity adjustment layer 2412G and the first blue sub-microcavity adjustment layer 2412B, the multiple sub-microcavities A1 can be made to meet a desired length by adjusting only the thicknesses of the first red sub-microcavity adjustment layer 2412R, the first green sub-microcavity adjustment layer 2412G, and the first blue sub-microcavity adjustment layer 2412B. Furthermore, the thicknesses of the shared film layers (e.g., the first auxiliary layer 22, the first light-emitting layer 23, a portion of the second auxiliary layer 24, 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 simplifies the manufacturing process of the shared film layers, and accordingly, simplifies the manufacturing process of the display substrate 100.

[0256] It should be noted that the thicknesses of the first red sub-microcavity adjustment layer 2412R, the first green sub-microcavity adjustment layer 2412G, and the first blue sub-microcavity adjustment layer 2412B have little effect on the electrical properties of the light-emitting device layer 2 in the display substrate 100. By adjusting the thicknesses of the first red sub-microcavity adjustment layer 2412R, the first green sub-microcavity adjustment layer 2412G, and the first blue sub-microcavity adjustment layer 2412B, and thus 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.

[0257] It can be understood that any one of the first red sub-microcavity adjustment layer 2412R, the first green sub-microcavity adjustment layer 2412G and the first blue sub-microcavity adjustment layer 2412B can include one film layer, or any one of the first red sub-microcavity adjustment layer 2412R, the first green sub-microcavity adjustment layer 2412G and the first blue sub-microcavity adjustment layer 2412B can include multiple film layers stacked in sequence.

[0258] In some examples, the first red sub-microcavity adjustment layer 2412R and the first green sub-microcavity adjustment layer 2412G each include one film layer.

[0259] For example, as shown in FIG6 , the first red sub-microcavity adjustment layer 2412R includes a red hole transport layer 2412R- 1 , and the first green sub-microcavity adjustment layer 2412G includes a green hole transport layer 2412G- 1 .

[0260] For example, the red hole transport layer 2412R-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 25R, thereby increasing the accumulation of holes in the second red light-emitting layer 25R and improving the luminous efficiency and luminous lifetime of the second red light-emitting layer 25R. The green hole transport layer 2412G-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.

[0261] In other embodiments, as shown in Figure 3, the first red sub-microcavity adjustment layer 2412R includes a red hole transport layer 2412R-1 and a red electron blocking layer 2412R-2 stacked in sequence in a direction away from the back plate 1, and the first green sub-microcavity adjustment layer 2412G includes a green hole transport layer 2412G-1 and a green electron blocking layer 2412G-2 stacked in sequence in a direction away from the back plate 1.

[0262] For example, the red hole transport layer 2412R-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 25R, thereby increasing the accumulation of holes in the second red light-emitting layer 25R and improving the luminous efficiency and luminous lifetime of the second red light-emitting layer 25R. The green hole transport layer 2412G-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.

[0263] Illustratively, the red electron blocking layer 2412R-2 is used to block electrons and / or excitons from escaping from the second red light-emitting layer 25R, thereby confining the electrons and / or excitons within the second red light-emitting layer 25R, thereby increasing the concentration of electrons and / or excitons within the second red light-emitting layer 25R, and thereby improving the luminance and luminous efficiency of the second red light-emitting layer 25R. The green electron blocking layer 2412G-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 within the second green light-emitting layer 25G, thereby increasing the concentration of electrons and / or excitons within the second green light-emitting layer 25G, and thereby improving the luminance and luminous efficiency of the second green light-emitting layer 25G.

[0264] In some examples, the red hole transport layer 2412R- 1 and the green hole transport layer 2412G- 1 are respectively used to adjust the length of the sub-microcavity A1 .

[0265] 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 2412R-1 and the green hole transport layer 2412G-1.

[0266] For example, by changing the thickness of the red hole transport layer 2412R-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 2412G-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.

[0267] It should be noted that the first auxiliary layer 22 may include one film layer or multiple film layers stacked in sequence. When the first auxiliary layer 22 includes multiple film layers, the multiple film layer structures of the first auxiliary layer 22 may have multiple schemes, and each film layer may have different functions, so that the first auxiliary layer 22 may have multiple functions.

[0268] In some embodiments, as shown in FIG. 7 , the first auxiliary layer 22 includes: a light-transmitting conductive layer 221 , a hole injection layer 222 , and a second microcavity adjustment layer 223 , which are sequentially stacked in a direction away from the back plate 1 .

[0269] Exemplarily, 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 by the anode layer 21 and the light-transmitting conductive layer 221.

[0270] Illustratively, the light-transmitting conductive layer 221 may be a single-layer structure, or the light-transmitting conductive layer 221 includes a plurality of film layers stacked in sequence.

[0271] For example, the material of the light-transmitting conductive layer 221 may include ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), and the like.

[0272] 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.

[0273] 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.

[0274] 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 2231 described below, 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 10 nm.

[0275] For example, the doping ratio of the P-type dopant in the material of the first hole transport layer 2231 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.

[0276] Exemplarily, the second microcavity adjustment layer 223 is used to adjust the length of the microcavity A. By adjusting the thickness of the portion of the second microcavity adjustment layer 223 that is opposite the second red light-emitting layer 25R, the second green light-emitting layer 25G, and the second blue light-emitting layer 25B, respectively, the corresponding colored light can produce a microcavity effect in the red sub-microcavity A1-R, the green sub-microcavity A1-G, and the blue sub-microcavity A1-B, thereby improving the color purity and luminous brightness of the light emitted from the sub-microcavity A1.

[0277] In some examples, as shown in FIG7 , the second microcavity adjustment layer 223 includes a first hole transport layer 2231, a second red sub-microcavity adjustment layer 2232R, a second green sub-microcavity adjustment layer 2232G, and a second blue sub-microcavity adjustment layer 2232B. The second red sub-microcavity adjustment layer 2232R is disposed between the first hole transport layer 2231 and the first red light-emitting layer 23R. The second green sub-microcavity adjustment layer 2232G is disposed between the first hole transport layer 2231 and the first green light-emitting layer 23G. The second blue sub-microcavity adjustment layer 2232B is disposed between the first hole transport layer 2231 and the first blue light-emitting layer 23B.

[0278] In some examples, the first hole transport layer 2231 is provided as a whole layer and has an adjustable thickness.

[0279] By providing the first hole transport layer 2231 as a whole layer, the manufacturing process of the display substrate 100 can be simplified.

[0280] By adjusting the thickness of the first hole transport layer 2231, the length of the microcavity A can be adjusted, so that the corresponding color light can produce a microcavity effect in the red sub-microcavity A1-R, green sub-microcavity A1-G and blue sub-microcavity A1-B, thereby improving the color purity and luminous brightness of the light emitted by the sub-microcavity A1.

[0281] For example, the HOMO (Highest Occupied Molecular Orbital) energy level of the hole injection layer 222 material and the HOMO energy level of the first hole transport layer 2231 material increase successively. Such a setting can reduce the hole injection barrier and improve the hole mobility, which is conducive to the injection of holes from the anode layer 21 and their sequential transmission to the first light-emitting layer 23 of the corresponding color, 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.

[0282] For example, the HOMO energy level of the material of the first hole transport layer 2231 ranges from -5.2 eV to -5.6 eV. For example, the HOMO energy level of the material of the first hole transport layer 2231 can be: -5.2 eV, -5.3 eV, -5.4 eV, -5.5 eV, or -5.6 eV.

[0283] For example, the material of the first hole transport layer 2231 includes a carbazole material having a high hole mobility. The first hole transport layer 2231 can be formed by an evaporation process.

[0284] For example, the second red sub-microcavity adjustment layer 2232R is used to lower the barrier for holes to be transferred from the first hole transport layer 2231 to the first red light-emitting layer 23R; the second green sub-microcavity adjustment layer 2232G is used to lower the barrier for holes to be transferred from the first hole transport layer 2231 to the first green light-emitting layer 23G; and the second blue sub-microcavity adjustment layer 2232B is used to lower the barrier for holes to be transferred from the first hole transport layer 2231 to the first blue light-emitting layer 23B. This can increase the mobility of holes transferred to the first light-emitting layer 23, increase the hole content in the first light-emitting layer 23, and enhance the brightness and luminous efficiency of the first light-emitting layer 23.

[0285] For example, the T1 of the materials of the second red sub-microcavity adjustment layer 2232R, the second green sub-microcavity adjustment layer 2232G, and the second blue sub-microcavity adjustment layer 2232B is higher than the T1 of the luminescent materials of the corresponding colors of the second light-emitting layer 25. This 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.

[0286] For example, the T1 of the materials of the second red sub-microcavity adjustment layer 2232R, the second green sub-microcavity adjustment layer 2232G, and the second blue sub-microcavity adjustment layer 2232B is at least 0.2 eV higher than the T1 of the light-emitting material of the first light-emitting layer 23 .

[0287] Exemplarily, the thicknesses of the second red sub-microcavity adjustment layer 2232R, the second green sub-microcavity adjustment layer 2232G, and the second blue sub-microcavity adjustment layer 2232B are individually adjustable. By adjusting the thicknesses of the second red sub-microcavity adjustment layer 2232R, the second green sub-microcavity adjustment layer 2232G, and the second blue sub-microcavity adjustment layer 2232B, respectively, the microcavity lengths of the corresponding red sub-microcavity A1-R, green sub-microcavity A1-G, and blue sub-microcavity A1-B can be adjusted, thereby enabling the corresponding color light to produce a microcavity effect in the red sub-microcavity A1-R, green sub-microcavity A1-G, and blue sub-microcavity A1-B, thereby improving the color purity and luminous brightness of the light emitted by the sub-microcavity A1.

[0288] Exemplarily, the thickness of the second blue sub-microcavity adjustment layer 2232B is less than or equal to 10 nm.

[0289] For example, the thickness of the second blue sub-microcavity adjustment layer 2232B can be 1 nm, 3 nm, 5 nm, 7 nm, or 10 nm.

[0290] In other embodiments, the first auxiliary layer 22 includes multiple film layers with different film layer structures. As shown in FIG8 , the first auxiliary layer 22 includes the light-transmitting conductive layer 221, the hole injection layer 222, and the second microcavity adjustment layer 223. The second microcavity adjustment layer 223 includes the first hole transport layer 2231 and the electron blocking layer 2233.

[0291] Exemplarily, the second microcavity adjustment layer 223 is used to adjust the length of the microcavity A. By adjusting the thickness of the portion of the second microcavity adjustment layer 223 that is opposite the second red light-emitting layer 25R, the second green light-emitting layer 25G, and the second blue light-emitting layer 25B, respectively, the corresponding colored light can produce a microcavity effect in the red sub-microcavity A1-R, the green sub-microcavity A1-G, and the blue sub-microcavity A1-B, thereby improving the color purity and luminous brightness of the light emitted from the sub-microcavity A1.

[0292] 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 2231 material, and the HOMO energy level of the electron blocking layer 2233 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.

[0293] Exemplarily, the HOMO energy level of the material of the electron blocking layer 2233 ranges from -5.5 eV to -5.9 eV. For example, the HOMO energy level of the material of the electron blocking layer 2233 includes: -5.5 eV, -5.6 eV, -5.7 eV, -5.8 eV, -5.9 eV, etc.

[0294] Illustratively, the T1 of the material of the electron blocking layer 2233 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.

[0295] For example, the T1 of the material of the electron blocking layer 2233 is at least 0.2 eV higher than the T1 of the light-emitting material in the first light-emitting layer 23 .

[0296] 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 relatively close, 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.

[0297] For example, as shown in FIG8 , 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 1 below.

[0298] Table 1

[0299] Film layer name Material type Refractive index Hole injection layer Carbazole doped radiata 1.74 First hole transport layer Carbazole 1.74 Electron blocking layer Carbazole 1.87 First hole blocking layer Triazine 1.88 First electron transport layer Triazine 2.00 First charge generation layer Phosphorus oxide 1.82 Second charge generation layer Carbazole doped radiata 1.74 Second hole transport layer Carbazole 1.74 Color sub-microcavity adjustment layer Carbazole 1.87 Second hole blocking layer Triazine 1.86 Second electron transport layer Triazine 1.79 Electron injection layer Metal complex 1.68

[0300] As shown in Table 1, 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 means that the refractive indices of any two of the film layers between the anode layer 21 and the cathode layer 27 are closer. By selecting the materials and refractive indices of the film layers between the anode layer 21 and the cathode layer 27, the difference in refractive index between any two of the film layers 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 ensuring that the light-emitting device 2a has good light extraction efficiency and reducing the dispersion of the light emitted by the light-emitting device 2a.

[0301] In some other embodiments, the first auxiliary layer 22 includes multiple film layers different from the above-mentioned two film layer structures. As shown in Figure 9, the first auxiliary layer 22 includes: the above-mentioned light-transmitting conductive layer 221, the above-mentioned hole injection layer 222 and the second microcavity adjustment layer 223 stacked in sequence along the direction away from the back plate 1.

[0302] The second microcavity adjustment layer 223 includes the first hole transport layer 2231, a second blue sub-microcavity adjustment layer 2232B, a second red sub-microcavity adjustment layer 2232R, and a second green sub-microcavity adjustment layer 2232G. The second blue sub-microcavity adjustment layer 2232B is disposed on the side of the first hole transport layer 2231 away from the backplane 1. The second red sub-microcavity adjustment layer 2232R is disposed between the second blue sub-microcavity adjustment layer 2232B and the first red light-emitting layer 23R. The second green sub-microcavity adjustment layer 2232G is disposed between the second blue sub-microcavity adjustment layer 2232B and the first green light-emitting layer 23G.

[0303] Exemplarily, the second microcavity adjustment layer 223 is used to adjust the length of the microcavity A. By adjusting the thickness of the portion of the second microcavity adjustment layer 223 that is opposite the second red light-emitting layer 25R, the second green light-emitting layer 25G, and the second blue light-emitting layer 25B, respectively, the corresponding colored light can produce a microcavity effect in the red sub-microcavity A1-R, the green sub-microcavity A1-G, and the blue sub-microcavity A1-B, thereby improving the color purity and luminous brightness of the light emitted from the sub-microcavity A1.

[0304] Exemplarily, the second blue sub-microcavity adjustment layer 2232B, the second red sub-microcavity adjustment layer 2232R, and the second green sub-microcavity adjustment layer 2232G are used to reduce the potential barrier for holes to be transferred from the first hole transport layer 2231 to the first light-emitting layer 23. By setting the second blue sub-microcavity adjustment layer 2232B as a whole layer, setting the second red sub-microcavity adjustment layer 2232R on the second blue sub-microcavity adjustment layer 2232B can further reduce the potential barrier for holes to be transferred from the first hole transport layer 2231 to the first red light-emitting layer 23R. Setting the second green sub-microcavity adjustment layer 2232G on the second blue sub-microcavity adjustment layer 2232B can further reduce the potential barrier for holes to be transferred from the first hole transport layer 2231 to the first green light-emitting layer 23G, thereby further increasing the mobility of holes and improving the luminous brightness and luminous efficiency of the first light-emitting layer 23.

[0305] Exemplarily, the thicknesses of the second blue sub-microcavity adjustment layer 2232B, the second red sub-microcavity adjustment layer 2232R, and the second green sub-microcavity adjustment layer 2232G are independently adjustable.

[0306] For example, when each color of light generates a microcavity effect in its corresponding sub-microcavity A1, the length of the blue sub-microcavity A1-B is the smallest. By providing the entire second blue sub-microcavity adjustment layer 2232B, and adjusting the thickness of the second blue sub-microcavity adjustment layer 2232B to produce a microcavity effect for blue light, as shown in FIG9 , the thickness adjustment amount of the second red sub-microcavity adjustment layer 2232R and the second green sub-microcavity adjustment layer 2232G can be reduced, thereby simplifying the manufacturing process of the second red sub-microcavity adjustment layer 2232R and the second green sub-microcavity adjustment layer 2232G in the display substrate 100.

[0307] It should be noted that the display substrate 100 can also adjust the peak position in the spectrum of the light emitted by the sub-microcavity A1 by adjusting the thickness of the above-mentioned second blue sub-microcavity adjustment layer 2232B, the second red sub-microcavity adjustment layer 2232R, and the second green sub-microcavity adjustment layer 2232G, thereby adjusting the color of the light.

[0308] In addition, the thicknesses of the hole injection layer 222, the first hole transport layer 2231, and the electron blocking layer 2233 in the above-described embodiment are all individually adjustable. These hole injection layer 222, the first hole transport layer 2231, and the electron blocking layer 2233 can all be used to adjust the length of the sub-microcavity A1, thereby improving the color purity and brightness of the light emitted by the sub-microcavity A1. Furthermore, by adjusting the length of the sub-microcavity A1, the peak position of the spectrum of the light emitted by the sub-microcavity A1 can be adjusted, thereby adjusting the color of the light.

[0309] It should be noted that either the second auxiliary layer 24 or the third auxiliary layer 26 may include one film layer or multiple film layers stacked in sequence. In the case where either the second auxiliary layer 24 or the third auxiliary layer 26 includes multiple film layers, each film layer may have different functions, thereby enabling the second auxiliary layer 24 or the third auxiliary layer 26 to have multiple functions.

[0310] In some examples, as shown in FIG8 , the second auxiliary layer 24 further includes: a first hole blocking layer 242 , a first electron transport layer 243 , a first charge generation layer 244 , and a second charge generation layer 245 , which are located on a side of the first microcavity adjustment layer 241 close to the back plate 1 and are stacked in sequence in a direction away from the back plate 1 .

[0311] In this case, as shown in FIG8 , the film layers located between the first auxiliary layer 22 and the third auxiliary layer 26 and opposite to the first blue light-emitting layer 23B include: the first blue light-emitting layer 23B, the first hole blocking layer 242, the first electron transport layer 243, the first charge generation layer 244, the second charge generation layer 245, the second hole transport layer 2411, the first blue sub-microcavity adjustment layer 2412B, and the second blue light-emitting layer 25B. The sum of the optical thicknesses of the film layers located between the first auxiliary layer 22 and the third auxiliary layer 26 and opposite to the first blue light-emitting layer 23B is the sum of the optical thicknesses of the first blue light-emitting layer 23B, the first hole blocking layer 242, the first electron transport layer 243, the first charge generation layer 244, the second charge generation layer 245, the second hole transport layer 2411, the first blue sub-microcavity adjustment layer 2412B, and the second blue light-emitting layer 25B. The sum of the actual thicknesses of the above-mentioned film layers located between the first auxiliary layer 22 and the third auxiliary layer 26 and opposite to the first blue light-emitting layer 23B is the sum of the actual thicknesses of the first blue light-emitting layer 23B, the first hole blocking layer 242, the first electron transport layer 243, the first charge generation layer 244, the second charge generation layer 245, the second hole transport layer 2411, the first blue sub-microcavity adjustment layer 2412B and the second blue light-emitting layer 25B.

[0312] Illustratively, the HOMO energy level absolute value of the material of the first hole blocking layer 242 is greater than the HOMO energy level absolute value of the material of the first light emitting layer 23. The first hole blocking layer 242 is used to prevent holes and / or excitons from leaking from the first light emitting layer 23.

[0313] For example, the absolute value of the HOMO energy level of the material of the first hole blocking layer 242 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.

[0314] Illustratively, the T1 of the material of the first hole blocking layer 242 is higher than the T1 of the light-emitting material included in the first light-emitting layer 23 .

[0315] For example, the T1 of the material of the first hole blocking layer 242 is higher than the T1 of the light emitting material included in the first light emitting layer 23 by at least 0.2 eV.

[0316] For example, the material of the first hole blocking layer 242 includes triazine materials and the like.

[0317] Exemplarily, the thickness of the first hole blocking layer 242 is less than or equal to 10 nm. For example, the thickness of the first hole blocking layer 242 is 1 nm, 3 nm, 5 nm, 8 nm, or 10 nm.

[0318] Exemplary materials for the first electron transport layer 243 include at least one of a thiophene material, an imidazole material, an azine derivative material, and lithium quinoline. The first electron transport layer 243 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%.

[0319] For example, the mass proportion of the lithium quinoline is 30%, 40%, 50%, 60% or 70%.

[0320] Exemplarily, the thickness of the first electron transport layer 243 ranges from 15 nm to 50 nm. For example, the thickness of the first electron transport layer 243 is 15 nm, 23 nm, 35 nm, 40 nm, or 50 nm.

[0321] Exemplarily, the first charge generation layer 244 and the second charge generation layer 245 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 .

[0322] For example, the first charge generation layer 244 can be formed by doping the material of the first electron transport layer 243 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 244 is less than or equal to 10 nm.

[0323] 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 244 may be 1 nm, 3 nm, 5 nm, 8 nm or 10 nm, etc.

[0324] For example, the second charge generation layer 245 can be formed by doping the second hole transport layer 2411 with a P-type dopant (such as MnO3 or F4TCNQ), with the doping ratio being less than or equal to 5%. The thickness of the first charge generation layer 244 is less than or equal to 10 nm.

[0325] 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 245 may be 1 nm, 3 nm, 5 nm, 8 nm or 10 nm, etc.

[0326] Alternatively, the first charge generation layer 244 may also be referred to as an N-type charge generation layer (N-CGL), and the second charge generation layer 245 may also be referred to as a P-type charge generation layer (P-CGL).

[0327] In some examples, as shown in FIG. 8 , the third auxiliary layer 26 includes: a second hole blocking layer 261 , a second electron transport layer 262 , and an electron injection layer 263 , which are sequentially stacked in a direction away from the back plate 1 .

[0328] 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.

[0329] 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.

[0330] 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 .

[0331] 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.

[0332] Exemplarily, the material of the second hole blocking layer 261 includes triazine materials and the like.

[0333] 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.

[0334] 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%.

[0335] For example, the mass proportion of the lithium quinoline may be 30%, 40%, 50%, 60% or 70%.

[0336] 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.

[0337] 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.

[0338] 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.

[0339] 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.

[0340] In some examples, as shown in FIG. 9 , the display substrate 100 further includes: an optical cover layer 3 and / or an encapsulation layer 4 sequentially stacked on the cathode layer 27 .

[0341] 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.

[0342] 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.

[0343] 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 .

[0344] Exemplarily, the packaging type of the packaging layer 4 includes: frame glue packaging or thin film packaging, etc.

[0345] In some examples, as shown in FIG10 , there are multiple second auxiliary layers 24 , and multiple first light-emitting layers 23 of at least two different colors or multiple second light-emitting layers 25 of at least two different colors are disposed between any two adjacent second auxiliary layers 24 .

[0346] For example, the number of the second auxiliary layer 24 , the first light-emitting layer 23 or the second light-emitting layer 25 is 2, 3, 4, 5 or 6.

[0347] 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 .

[0348] By setting up multiple second light-emitting layers 25, the total intensity of light that the second light-emitting layer 25 can emit can be increased, thereby increasing the absorption of light emitted by the first light-emitting layer 23 by the second light-emitting layer 25, thereby increasing the intensity of the excitation light of the second light-emitting layer 25, and increasing the luminous brightness of the display substrate 100.

[0349] By providing a plurality of second auxiliary layers 24 , it is possible to ensure that holes and electrons can be transported to the plurality of first light-emitting layers 23 and second light-emitting layers 25 to generate excitons, thereby causing the first light-emitting layers 23 and second light-emitting layers 25 to emit light.

[0350] The inventors of the present disclosure have verified the color purity and luminous efficiency of the display substrate 100 of the present disclosure.

[0351] Verification Example 1: includes Comparative Example 1 and Example 1.

[0352] The first display substrate of comparative example 1 has a red light-emitting device, a green light-emitting device, and a blue light-emitting device, and the display substrate includes an anode layer, a light-transmitting conductive layer, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer (for example, 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 stacked in sequence.

[0353] The red light-emitting layer in the red light-emitting device in the first display substrate includes a red main material and a red fluorescent material containing a boron element, and the mass proportion of the red fluorescent material is 5%; the green light-emitting layer in the green light-emitting device includes a green main material and a green fluorescent material with multiple resonance characteristics, and the mass proportion of the green fluorescent material is 5%; the blue light-emitting layer in the blue light-emitting device includes a blue main material and a deep blue fluorescent material, and the mass proportion of the deep blue fluorescent material is 1%.

[0354] The thicknesses of the film layers corresponding to the light-emitting devices in the first display substrate of Comparative Example 1 are shown in Table 2 below.

[0355] Table 2

[0356] First display substrate project Red light-emitting device Green light-emitting device Blue light-emitting device Anode layer thickness (nm) 100 100 100 Transparent conductive layer thickness (nm) 888 Hole injection layer thickness (nm) 1010 10 Hole transport layer thickness (nm) 1515 15 Electron blocking layer thickness (nm) 555 Luminescent layer thickness (nm) 2030 20 Hole blocking layer thickness (nm) 1010 5 Electron transport layer thickness (nm) 353535 Electron injection layer thickness (nm) 111 Cathode layer thickness (nm) 1515 15

[0357] The second display substrate of Comparative Example 1 has the same structure as the first display substrate.

[0358] The red light-emitting layer in the red light-emitting device in the second display substrate includes an ordinary P-type red main material and a red light-emitting material with thermally activated delayed fluorescence characteristics, and the mass proportion of the red light-emitting material is 30%; the green light-emitting layer in the green light-emitting device includes an ordinary P-type green main material and a green light-emitting material with thermally activated delayed fluorescence characteristics, and the mass proportion of the green light-emitting material is 30%; the blue light-emitting layer in the blue light-emitting device includes a blue main material and a blue fluorescent material containing boron element, and the mass proportion of the blue fluorescent material is 1%.

[0359] The thicknesses of the film layers corresponding to the light-emitting devices in the second display substrate of Comparative Example 1 are shown in Table 3 below.

[0360] Table 3

[0361] Second display substrate item Red light-emitting device Green light-emitting device Blue light-emitting device Transparent conductive layer thickness (nm) 707070 Hole injection layer thickness (nm) 101010 Hole transport layer thickness (nm) 100100100 Electron blocking layer thickness (nm) 555 Luminescent layer thickness (nm) 203020 Hole blocking layer thickness (nm) 555 Electron transport layer thickness (nm) 353535 Electron injection layer thickness (nm) 111 Cathode layer thickness (nm) 100100100

[0362] 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.

[0363] In Example 1, the material of the first light-emitting layer 23 is the same as that of the light-emitting layer of the second display substrate in Comparative Example 1. The material of the second light-emitting layer 25 is the same as that of the light-emitting layer of the first display substrate in Comparative Example 1.

[0364] The thickness of each film layer corresponding to each light-emitting device in the display substrate 100 of Example 1 is shown in Table 4 below.

[0365] Table 4

[0366] Item Red light-emitting device Green light-emitting device Blue light-emitting device Anode layer thickness (nm) 100 100 100 Transparent conductive layer thickness (nm) 888 Hole injection layer thickness (nm) 1010 10 First hole transport layer thickness (nm) 20 20 20 Electron blocking layer thickness (nm) 555 First luminescent layer thickness (nm) 20 30 20 First hole blocking layer thickness (nm) 888 First electron transport layer thickness (nm) 121 212 First charge generation layer thickness (nm) 1010 10 Second charge generation layer thickness (nm) 1010 10 Second hole transport layer thickness (nm) 35 35 35 Thickness of each color microcavity adjustment layer (nm) 151 515 Second luminescent layer thickness (nm) 20 30 20 Second hole blocking layer thickness (nm) 555 Second electron transport layer thickness (nm) 35 35 35 Electron injection layer thickness (nm) 111 Cathode layer thickness (nm) 151 515

[0367] 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.

[0368] As shown in Figures 11 and 12, the horizontal axis in the graphs represents wavelength (in nm), and the vertical axis represents relative spectral intensity. As shown in Figure 11, the emission spectrum p1 of the luminescent material of the red luminescent layer of the second display substrate in Comparative Example 1 overlaps with the absorption spectrum p2 of the luminescent material of the red luminescent layer of the first display substrate. As shown in Figure 12, the emission spectrum p3 of the luminescent material of the green luminescent layer of the second display substrate in Comparative Example 1 overlaps with the absorption spectrum p4 of the luminescent material of the green luminescent layer of the first display substrate.

[0369] The comparison of the relevant quantities of the first display substrate of Comparative Example 1 and the display substrate of Example 1 is shown in Table 5.

[0370] Among them, in the second display substrate of comparative example 1, the driving voltage of the red light-emitting device is 4.0V, the luminous brightness is 3000nits, the color coordinates are (0.552, 0.446), and the luminous efficiency is 40cd / A; the driving voltage of the green light-emitting device is 3.7V, the luminous brightness is 10000nits, the color coordinates are (0.340, 0.599), and the luminous efficiency is 55cd / A.

[0371] Table 5

[0372]

[0373] The above results demonstrate that when the second light-emitting layer 25 of the light-emitting device of Example 1 is combined with the first light-emitting layer 23 in series, both the red and green light-emitting devices of Example 1 exhibit several times higher efficiency and several times higher lifetime at the same brightness compared to the corresponding color light-emitting devices in the first display substrate of Comparative Example 1. In Example 1, the second light-emitting layer 25 and the first light-emitting layer 23 have identical component compositions, forming a series structure. Therefore, the efficiency and lifetime at the same brightness are also significantly improved compared to the blue light-emitting device in the second display substrate.

[0374] Verification Example 2: includes Example 2-1, Example 2-2 and Example 2-3.

[0375] Except that the red microcavity adjustment layer and the second red light-emitting layer also include a red electron blocking layer, and the green microcavity adjustment layer and the second green light-emitting layer also include a green electron blocking layer, the display substrates 100 of Examples 2-1, 2-2, and 2-3 have the same film structure and film material as the display substrate 100 of Example 1.

[0376] The thicknesses of the film layers corresponding to the light-emitting devices in the display substrate of Example 2-1 are shown in Table 6 below.

[0377] Table 6

[0378] Item Red light-emitting device Green light-emitting device Blue light-emitting device Anode layer thickness (nm) 100 100 100 Transparent conductive layer thickness (nm) 888 Hole injection layer thickness (nm) 1010 10 First hole transport layer thickness (nm) 20 20 20 Second microcavity adjustment layer thickness (nm) 555 First light-emitting layer thickness (nm) 20 20 20 First hole blocking layer thickness (nm) 888 First electron transport layer thickness (nm) 1010 10 First charge generation layer thickness (nm) 888 Second charge generation layer thickness (nm) 1010 10 Second hole transport layer thickness (nm) 39 39 39 Microcavity adjustment layer thicknesses of various colors (nm) 1010 15 Electron blocking layer thicknesses of various colors (nm) 55 None Second light-emitting layer thickness (nm) 20 20 20 Second hole blocking layer thickness (nm) 555 Second electron transport layer thickness (nm) 35 35 35 Electron injection layer thickness (nm) 111 Cathode layer thickness (nm) 15 15 15

[0379] The thicknesses of the film layers corresponding to the light-emitting devices in the display substrate of Example 2-2 are shown in Table 7 below.

[0380] Table 7

[0381] Item Red light-emitting device Green light-emitting device Blue light-emitting device Anode layer thickness (nm) 100 100 100 Transparent conductive layer thickness (nm) 888 Hole injection layer thickness (nm) 1010 10 First hole transport layer thickness (nm) 30 30 30 Second microcavity adjustment layer thickness (nm) 555 First light-emitting layer thickness (nm) 20 20 20 First hole blocking layer thickness (nm) 888 First electron transport layer thickness (nm) 1010 10 First charge generation layer thickness (nm) 888 Second charge generation layer thickness (nm) 1010 10 Second hole transport layer thickness (nm) 29 29 29 Microcavity adjustment layer thicknesses of various colors (nm) 1010 15 Electron blocking layer thicknesses of various colors (nm) 55 None Second light-emitting layer thickness (nm) 20 20 20 Second hole blocking layer thickness (nm) 555 Second electron transport layer thickness (nm) 35 35 35 Electron injection layer thickness (nm) 111 Cathode layer thickness (nm) 15 15 15

[0382] The thicknesses of the film layers corresponding to the light-emitting devices in the display substrates of Examples 2-3 are shown in Table 8 below.

[0383] Table 8

[0384] Item Red light-emitting device Green light-emitting device Blue light-emitting device Anode layer thickness (nm) 100 100 100 Transparent conductive layer thickness (nm) 888 Hole injection layer thickness (nm) 1010 10 First hole transport layer thickness (nm) 40 40 40 Second microcavity adjustment layer thickness (nm) 555 First light-emitting layer thickness (nm) 20 20 20 First hole blocking layer thickness (nm) 888 First electron transport layer thickness (nm) 1010 10 First charge generation layer thickness (nm) 888 Second charge generation layer thickness (nm) 1010 10 Second hole transport layer thickness (nm) 19 19 19 Microcavity adjustment layer thicknesses of various colors (nm) 1010 15 Electron blocking layer thicknesses of various colors (nm) 55 None Second light-emitting layer thickness (nm) 20 20 20 Second hole blocking layer thickness (nm) 555 Second electron transport layer thickness (nm) 35 35 35 Electron injection layer thickness (nm) 111 Cathode layer thickness (nm) 15 15 15

[0385] In the above three embodiments, the size of L1 is adjusted by changing the thickness of the first hole transport layer closer to the anode layer, and the sub-microcavity lengths of each light-emitting device are kept consistent by adjusting the thickness of the corresponding second hole transport layer farther from the anode layer.

[0386] The light-emitting parameters of each light-emitting device in Example 2-1, Example 2-2, and Example 2-3 are shown in Table 9 below.

[0387] Table 9

[0388]

[0389] From the above results, it can be seen from the comparison that when the thickness of the first hole transport layer closer to the anode layer continues to increase, the overall characteristics of the red and green light-emitting devices change less significantly, but the efficiency of the blue light-emitting device decreases significantly, and the color purity also decreases significantly.

[0390] As shown in Figure 13, the spectra of the blue light-emitting devices of Examples 2-1, 2-2, and 2-3 are p3, p4, and p5, respectively. Further observations from corresponding bottom-emission experiments show that as the thickness of the first hole transport layer increases, the emission spectrum of the blue light-emitting devices broadens and develops a distinct double-peak structure. This spectral change is clearly correlated with the decrease in luminous efficiency and color purity of top-emitting devices.

[0391] In Example 2-3, the luminous efficiency of the blue light-emitting device in the substrate is too low (less than 90%).

[0392] |L1-L2}=51.8nm, which does not conform to the formula in this disclosure: |L1-L2}≤37nm (corresponding to the blue light target wavelength, corresponding to ), and was judged as unqualified.

[0393] 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: Back panel; 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, with a microcavity formed between the anode layer and the cathode layer; a plurality of first light-emitting layers of at least two different colors disposed between the first auxiliary layer and the second auxiliary layer, the plurality of first light-emitting layers including at least a plurality of first blue light-emitting layers; 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 plurality of second light-emitting layers including at least a plurality of second blue light-emitting layers; The first auxiliary layer includes a number of film layers stacked in sequence, and the optical thickness of the portion of the a film layer facing the first blue light-emitting layer is L1, and L1 satisfies: a is a positive integer, n h is the refractive index of the hth film layer among the a film layers, r h is the thickness of the hth film layer; The third auxiliary layer includes b layers stacked in sequence, and the optical thickness of the portion of the b layers facing the first blue light-emitting layer is L2, and L2 satisfies: b is a positive integer, n i is the refractive index of the i-th film layer among the b film layers, r i is the thickness of the i-th film layer; L1 and L2 satisfy the formula: is the average refractive index of the layer located between the first auxiliary layer and the third auxiliary layer and opposite to the first blue light-emitting layer to the central wavelength of blue light, λ B is the peak wavelength of the blue light target spectrum, and k is a positive integer.

2. The display substrate according to claim 1, wherein The plurality of first light-emitting layers further include a plurality of first red light-emitting layers and a plurality of first green light-emitting layers; The first red light-emitting layer and the first blue light-emitting layer have different thicknesses, and / or the first green light-emitting layer and the first blue light-emitting layer have different thicknesses.

3. The display substrate according to claim 2, wherein: The plurality of second light-emitting layers further include: a plurality of second red light-emitting layers and a plurality of second green light-emitting layers; The second red light-emitting layer and the second blue light-emitting layer have different thicknesses, and / or the second green light-emitting layer and the second blue light-emitting layer have different thicknesses.

4. The display substrate according to claim 3, wherein: The second auxiliary layer includes: a first microcavity adjustment layer; The thickness of a portion of the first microcavity adjustment layer opposite to the second red light-emitting layer is different from the thickness of a portion of the first microcavity adjustment layer opposite to the second blue light-emitting layer, and / or the thickness of a portion of the first microcavity adjustment layer opposite to the second green light-emitting layer is different from the thickness of a portion of the first microcavity adjustment layer opposite to the second blue light-emitting layer.

5. The display substrate according to claim 4, wherein: The first microcavity adjustment layer includes: a second hole transport layer; a first red sub-microcavity adjustment layer disposed between the second hole transport layer and the second red light-emitting layer; a first green sub-microcavity adjustment layer disposed between the second hole transport layer and the second green light-emitting layer; and a first blue sub-microcavity adjustment layer disposed between the second hole transport layer and the second blue light-emitting layer; The first red sub-microcavity adjustment layer and the first blue sub-microcavity adjustment layer have different thicknesses, and / or the first green sub-microcavity adjustment layer and the first blue sub-microcavity adjustment layer have different thicknesses. The display substrate according to claim 5 , wherein: The first 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 first 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; The red hole transport layer and the green hole transport layer are respectively used to adjust the length of the microcavity.

7. The display substrate according to any one of claims 3 to 6, wherein The wavelength of light emitted by the first light-emitting layer of at least one color is shorter than the wavelength of light emitted by the second light-emitting layer of the corresponding color.

8. The display substrate according to any one of claims 3 to 7, 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 of the first light-emitting layer of at least one color at least partially overlaps with the absorption spectrum of the second guest material of the second light-emitting layer of the corresponding color.

9. The display substrate according to claim 8, 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.

10. The display substrate according to claim 8, 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.

11. The display substrate according to any one of claims 8 to 10, wherein The peak value of the emission spectrum of the first guest material of the first red light-emitting layer is in the range of 560 nm to 570 nm, 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 595 nm to 605 nm.

12. The display substrate according to any one of claims 8 to 11, wherein The peak of the emission spectrum of the first guest material of the first green light-emitting layer is in the range of 500 nm to 510 nm, and the peak of the absorption spectrum of the second guest material of the second green light-emitting layer is in the range of 515 nm to 525 nm.

13. The display substrate according to any one of claims 8 to 12, wherein The first guest material of the first light-emitting layer of at least one color includes at least one light-emitting 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.

14. The display substrate according to claim 13, wherein: 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 is in the range of 0.5% to 5%.

15. The display substrate according to any one of claims 8 to 14, wherein The second guest material of the second light-emitting layer of at least one color includes 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.

16. The display substrate according to claim 15, wherein: The second guest material includes two light-emitting materials; At least one of the two luminescent materials is doped with boron, and the doping ratio of the boron is in the range of 0.5% to 5%.

17. The display substrate according to any one of claims 8 to 16, 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 having multiple resonance characteristics.

18. The display substrate according to any one of claims 8 to 17, wherein The first light-emitting layer further includes a first host material, which is a single host material or a PN mixed host material; The second light-emitting layer further includes a second host material, and the second host material includes a bipolar host material.

19. The display substrate according to claim 18, wherein: The second host material is 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 host material of the N-type component has a thermally activated delayed fluorescence characteristic.

20. The display substrate according to any one of claims 3 to 19, wherein The first red light-emitting layer and the second red light-emitting layer are arranged opposite to each other, the first green light-emitting layer and the second green light-emitting layer are arranged opposite to each other, and the first blue light-emitting layer and the second blue light-emitting layer are arranged opposite to each other.

21. The display substrate according to any one of claims 2 to 20, wherein The first auxiliary layer includes: A light-transmitting conductive layer, a hole injection layer, and a second microcavity adjustment layer are sequentially stacked in a direction away from the back plate; The second microcavity adjustment layer includes: a first hole transport layer; a second red sub-microcavity adjustment layer disposed between the first hole transport layer and the first red light-emitting layer; a second green sub-microcavity adjustment layer disposed between the first hole transport layer and the first green light-emitting layer; and A second blue sub-microcavity adjustment layer is disposed between the first hole transport layer and the first blue light-emitting layer.

22. The display substrate according to any one of claims 2 to 20, wherein: The first auxiliary layer includes a light-transmitting conductive layer, a hole injection layer, and a second microcavity adjustment layer stacked in sequence in a direction away from the back plate; The second microcavity adjustment layer includes: a first hole transport layer and an electron blocking layer.

23. The display substrate according to any one of claims 2 to 20, wherein The first auxiliary layer includes: A light-transmitting conductive layer, a hole injection layer, and a second microcavity adjustment layer are sequentially stacked in a direction away from the back plate; The second microcavity adjustment layer includes: a first hole transport layer; a second blue sub-microcavity adjustment layer provided on a side of the first hole transport layer away from the back plate; a second red sub-microcavity adjustment layer disposed between the second blue sub-microcavity adjustment layer and the first red light-emitting layer; and A second green sub-microcavity adjustment layer is provided between the second blue sub-microcavity adjustment layer and the first green light-emitting layer.

24. The display substrate according to any one of claims 2 to 23, wherein The microcavity includes a plurality of sub-microcavities, wherein the plurality of sub-microcavities include a red sub-microcavity corresponding to the first red light-emitting layer, a green sub-microcavity corresponding to the first green light-emitting layer, and a blue sub-microcavity corresponding to the first 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 c, and the optical thickness of the c film layers is L3, where L3 satisfies: c is a positive integer, n j is the refractive index of the jth film layer among the c film layers, r j is the thickness of the j-th film layer; The sub-microcavity of any color satisfies: m is a natural number, λ is the interference wavelength, is the phase shift caused by the anode layer.

25. The display substrate according to claim 24, 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.

26. The display substrate according to any one of claims 4 to 25, wherein The second auxiliary layer further includes: a first hole blocking layer, a first electron transport layer, a first charge generation layer, and a second charge generation layer, which are located on a side of the first microcavity adjustment layer close to the back plate and are stacked in sequence in a direction away from the back plate; and / or, The third auxiliary layer includes: a second hole blocking layer, a second electron transport layer, and an electron injection layer, which are sequentially stacked in a direction away from the back plate.

27. The display substrate according to claim 26, wherein: 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.

28. The display substrate according to any one of claims 1 to 27, wherein The thickness of the first blue light-emitting layer is in the range of 15 nm to 60 nm; and / or, The thickness of the second blue light emitting layer is in the range of 10 nm to 50 nm.

29. The display substrate according to any one of claims 1 to 28, wherein There are multiple second auxiliary layers, and multiple first light-emitting layers of at least two different colors or multiple second light-emitting layers of at least two different colors are arranged between any two adjacent second auxiliary layers.

30. A display device comprising: The display substrate according to any one of claims 1 to 29.

Images