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

Abstract

The application relates to the technical field of display, in particular to a display panel, a preparation method thereof and a display device. The display panel comprises a substrate, an OLED arranged on the substrate, the OLED comprising a plurality of pixel units arranged in an array and a hole transport layer, an electron transport layer and a cathode shared by all the pixel units, an anode and a light-emitting layer arranged in each pixel unit, an OPD integrated in a pixel array arrangement area of the OLED, the OPD comprising an anode and a photosensitive layer, the material of the photosensitive layer comprising a donor material and an acceptor material, the OPD sharing the hole transport layer of the OLED, and the donor material being the same as the material of the hole transport layer. The application not only avoids the introduction of an additional material system and an independent functional layer, but also effectively suppresses reverse leakage current and optimizes charge transport by using deeper HOMO and LUMO energy levels, and simultaneously realizes low dark current and high external quantum efficiency.

Description

Technical Field

[0001] This invention relates to the field of display technology, and more specifically, to a display panel, its manufacturing method, and a display device. Background Technology

[0002] With the widespread adoption of mobile devices, in-display fingerprint recognition technology has become the mainstream unlocking method for smartphones, tablets, and other electronic devices. Currently, the mainstream in-display fingerprint recognition solutions are mainly divided into two categories: optical and ultrasonic. Among them, optical fingerprint recognition is widely used due to its mature technology and relatively low cost.

[0003] Existing optical under-display fingerprint recognition solutions typically employ an external module structure, where the fingerprint sensor module is attached to the back of the display panel (non-display side). The fingerprint image is captured by the sensor receiving the reflected light from the screen when the finger is illuminated. However, this external solution suffers from limitations such as a limited fingerprint recognition area, large module thickness, and high cost.

[0004] In recent years, some research has attempted to integrate photodetectors directly into the display panel. For example, some solutions place the photodetector in the non-opening area between display pixels (i.e., pixel gaps), or place the fingerprint recognition area in the non-display area of ​​the display panel (such as the lower bezel). However, these solutions still cannot achieve fingerprint recognition across the entire display area, and the process compatibility between the detector and the display pixels still needs improvement.

[0005] In integrated solutions, organic photodetectors (OPDs) are considered the most promising technology for achieving deep integration of display and sensing due to their similar material systems and device structures to organic electroluminescent displays (OLEDs). OPD devices typically include an anode, hole transport layer (HTL), photosensitive layer (including donor and acceptor layers), electron transport layer (ETL), and cathode. Their structure is highly similar to that of OLEDs, the difference being that the OLED's light-emitting layer is replaced by the OPD's photosensitive layer.

[0006] Although OPD and OLED have similar structures, in existing integration schemes, OPD devices and OLED devices typically use their own independent functional layer material systems, lacking material sharing and structural integration. Specifically, existing technologies mainly suffer from the following technical problems: First, the material systems are incompatible, leading to complex processes. In existing solutions, the donor material for OPD devices is usually different from the HTL material for OLED devices. This means that OPD and OLED cannot share the same evaporation equipment and material system, requiring additional evaporation processes and material types, which increases manufacturing complexity and cost.

[0007] Secondly, the functional layers cannot be shared, increasing the module thickness. Because OPD and OLED each use independent HTL and ETL, they cannot share film layers. This results in two sets of functional layers needing to be set in the display panel, which not only increases the overall film thickness, hindering the thinner and lighter design of terminal devices, but also increases interface defects and leakage current, affecting device performance.

[0008] Third, the fingerprint recognition area is limited. Most existing integrated solutions place the OPD device in the gap area between display pixels or in the non-display area of ​​the display panel, which cannot achieve fingerprint recognition at any position across the entire display area. Users still need to press in a specific area, affecting the user experience.

[0009] Fourth, there is a lack of feasible solutions for in-pixel integration. Existing technologies have not yet proposed a technical solution for fully integrating OPD devices inside OLED display pixels and sharing functional layer materials and structures with OLED devices, which limits the deep integration of display and sensing.

[0010] Accordingly, a new technical solution is needed in this field to solve the above-mentioned technical problems. Summary of the Invention

[0011] The present invention aims to solve the above-mentioned technical problems, namely, to solve the problems of high process complexity and cost, limited fingerprint recognition area, and lack of feasible solutions for in-pixel integration caused by the incompatibility of OPD and OLED material systems and the inability to share functional layers in existing under-display fingerprint recognition solutions.

[0012] In a first aspect, the present invention provides a display panel comprising: substrate; An organic electroluminescent display device is disposed on the substrate. The organic electroluminescent display device includes multiple pixel units arranged in an array and a hole transport layer (HTL), an electron transport layer (ETL), and a cathode shared by all pixel units. Each pixel unit is provided with a first anode and a light-emitting layer. An organic photodetector is integrated into the pixel array layout area of ​​the organic electroluminescent display device; in: The organic photodetector includes a second anode and a photosensitive layer; the photosensitive layer is made of a donor material and an acceptor material. The organic photodetector shares the hole transport layer of the organic electroluminescent display device; the donor material is the same as the material of the hole transport layer.

[0013] In the preferred embodiment of the above-mentioned display panel, the organic photodetector shares the electron transport layer of the organic electroluminescent display device.

[0014] In the preferred embodiment of the above-mentioned display panel, the organic photodetector shares the cathode of the organic electroluminescent display device.

[0015] In the preferred embodiment of the above-mentioned display panel, the hole transport layer has a highest occupied molecular orbital energy level of less than -5.6 eV and a lowest unoccupied molecular orbital energy level of less than -2.9 eV.

[0016] In the preferred embodiment of the above-described display panel, the second anode is made of the same material as the first anode.

[0017] In the preferred embodiment of the above-mentioned display panel, the photosensitive layer is a planar heterojunction structure; the planar heterojunction structure is any one of the following two structures: (i) A donor layer and an acceptor layer are stacked sequentially, wherein the donor layer is in direct contact with the hole transport layer, and the acceptor layer is in direct contact with the electron transport layer; or (ii) A receptor layer, wherein at least a portion of the hole transport layer serves as a donor layer, the receptor layer is in direct contact with the hole transport layer serving as a donor layer, and the receptor layer is in direct contact with the electron transport layer.

[0018] In the preferred embodiment of the above-mentioned display panel, the photosensitive layer is a bulk heterojunction structure; the bulk heterojunction structure comprises a mixture of the donor material and the acceptor material.

[0019] In the preferred embodiment of the above-mentioned display panel, the light-emitting layer of each pixel unit includes a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer; the photosensitive layer is arranged side by side with the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer on the same layer.

[0020] In the preferred embodiment of the above-mentioned display panel, multiple organic photodetectors are arranged in an array to form a fingerprint recognition sensor array.

[0021] In the preferred embodiment of the above-mentioned display panel, the arrangement of the plurality of organic photodetectors includes at least one of the following: It is embedded between adjacent light-emitting layers inside the pixel unit, arranged between adjacent pixel units, and arranged around the periphery of the pixel unit.

[0022] In a second aspect, the present invention provides a method for manufacturing a display panel, comprising the following steps: Provide a substrate; A first anode of an organic electroluminescent display device and a second anode of an organic photodetector are formed on the substrate; A hole transport layer is formed on the first anode and the second anode, and the hole transport layer serves as both the hole transport layer of the organic electroluminescent display device and the hole transport layer of the organic photodetector. On the hole transport layer, an emissive layer and a photosensitive layer are formed in the regions of the organic electroluminescent display device and the organic photodetector, respectively; the photosensitive layer includes a donor material and an acceptor material, wherein the donor material is the same material as the hole transport layer; An electron transport layer for an organic electroluminescent display device is formed on the light-emitting layer, and an electron transport layer for an organic photodetector is formed on the photosensitive layer. The cathode of the organic electroluminescent display device is formed on the electron transport layer of the organic electroluminescent display device, and the cathode of the organic photodetector is formed on the electron transport layer of the organic photodetector.

[0023] In the preferred embodiment of the above preparation method, the organic photodetector shares the electron transport layer of the organic electroluminescent display device and is formed synchronously through the same evaporation process.

[0024] In the preferred embodiment of the above preparation method, the organic photodetector shares the cathode of the organic electroluminescent display device and is formed synchronously through the same evaporation process.

[0025] In the preferred embodiment of the above preparation method, the second anode and the first anode are formed simultaneously through the same patterning process.

[0026] In the preferred embodiment of the above preparation method, when the photosensitive layer adopts a planar heterojunction structure, the steps are performed using any one of the following two preparation methods: (1) Donor material and acceptor material are sequentially deposited on the hole transport layer to form a donor layer and an acceptor layer; or (2) At least a portion of the hole transport layer is used as a donor layer, and acceptor material is deposited on the portion of the hole transport layer used as the donor layer to form an acceptor layer; When the photosensitive layer adopts a bulk heterojunction structure, the steps are as follows: co-evaporation includes a mixture of donor and acceptor materials.

[0027] In the preferred embodiment of the above preparation method, the organic photodetectors are multiple and arranged in an array to form a fingerprint recognition sensor array; the photosensitive layers of the multiple organic photodetectors are prepared simultaneously with the multiple pixel units of the organic electroluminescent display device.

[0028] In a third aspect, the present invention provides a display device comprising the display panel described in the first aspect or the display panel prepared by the preparation method described in the second aspect.

[0029] By adopting the above technical solution, the present invention can achieve the following beneficial effects: (1) Material system compatibility and process integration between OPD and OLED have been achieved. By setting the donor material of the organic photodetector to be the same as the hole transport layer material of the organic electroluminescent display device, the present invention enables OPD and OLED to share the same hole transport layer material system without the need to add additional donor material types and evaporation processes, simplifying the process flow and reducing manufacturing costs; (2) The shared use of film layers for functional layers is achieved, which is beneficial for thinner and lighter designs. By setting the hole transport layer of the organic photodetector and the hole transport layer of the organic electroluminescent display device as the same material layer, and further optionally setting the electron transport layer and / or cathode as the same material layer, the shared use of film layers for OPD and OLED is achieved, avoiding the increase in thickness caused by setting two sets of functional layers separately, which is beneficial for thinner and lighter designs of terminal devices, while reducing interface defects and leakage current, and improving device performance; (3) The fingerprint recognition function of the entire display area is realized. The present invention integrates organic photodetectors into the pixel unit of organic electroluminescent display device and sets them side by side with red sub-pixels, green sub-pixels and blue sub-pixels on the same layer. Multiple organic photodetectors are arranged in an array, realizing fingerprint recognition at any position of the entire display area. Users do not need to press in a specific area, which improves the user experience. (4) It provides multiple implementation methods for planar heterojunctions and bulk heterojunctions. The photosensitive layer of the organic photodetector of the present invention can adopt a planar heterojunction structure (including two methods: independent vapor deposition of the donor layer or using the hole transport layer as the donor layer) or a bulk heterojunction structure, which has rich process selection flexibility and can optimize device performance according to actual needs; (5) A complete preparation method is provided, realizing integrated protection of the product and the process. This invention simultaneously protects the display panel, the display device and its preparation method. By forming a common layer simultaneously in the same evaporation process and forming an anode simultaneously in the same patterning process, the collaborative manufacturing of OPD and OLED is realized, improving production efficiency. Attached Figure Description

[0030] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which: Figure 1 This is a schematic diagram of the display panel structure of the present invention; Figure 2 This is a schematic diagram of the planar structure of the pixel unit of the display panel in one embodiment of the present invention; Figure 3This is a schematic diagram of the structure of an OPD device in one embodiment of the present invention, wherein the photosensitive layer is a planar heterojunction structure; Figure 4 This is a schematic diagram of an OPD device with a bulk heterojunction structure as the photosensitive layer in another embodiment of the present invention; Figure 5 This is a schematic diagram of the planar structure of the pixel unit of the display panel in another embodiment of the present invention; Figure 6 This is a schematic diagram of the planar structure of the pixel unit of the display panel in another embodiment of the present invention; Figure 7 This is a process flow diagram of the method for manufacturing the display panel of the present invention; Figure 8 This is the UV-Vis absorption spectrum of the donor material (SubPc) in Comparative Example 1; Figure 9 This is the external quantum efficiency (EQE) spectrum of the OPD device prepared in Example 1 of the present invention under different bias voltages; Figure 10 This is a current density-voltage (JV) characteristic curve of the OPD device obtained in Embodiment 1 of the present invention; The markings in the diagram are as follows: 1——Substrate; 2—Organic electroluminescent display device, 21—First anode, 22—Hole transport layer, 23—Emitting layer, 231—Red emitting layer, 232—Green emitting layer, 233—Blue emitting layer, 24—Electron transport layer, 25—Cathode; 3 – Organic photodetector, 31 – Second anode, 33 – Photosensitive layer, 331 – Donor layer, 332 – Acceptor layer. Detailed Implementation

[0031] Organic light-emitting diodes (OLEDs) have been identified as a highly promising display technology due to their advantages, including thinness, light weight, wide viewing angle, active emission, continuously adjustable emission color, low cost, fast response speed, low power consumption, low driving voltage, wide operating temperature range, simple manufacturing process, high luminous efficiency, and flexible display capabilities. Integrating OPDs into OLED panels to achieve under-display fingerprint recognition is one of the important development directions of current display technology.

[0032] In related OLED display technologies, fingerprint recognition is achieved by integrating an organic photodetector (OPD) unit into the OLED display panel. The main principle is that the finger reflects the light emitted by the OLED light-emitting unit to the OPD unit, which then converts the light signal into an electrical signal, thereby recognizing the user's fingerprint information.

[0033] An OPD (Optical Distribution Device) is an optoelectronic device that converts incident light signals into electrical signals, while an OLED (Optical Display Device) converts electrical signals into light signals. An OPD typically consists of a cathode, an anode, a photosensitive layer (or photoelectric sensing structure), and a carrier layer. The photosensitive layer is the core component for photoelectric conversion and is usually composed of donor and acceptor materials.

[0034] The photosensitive layer in OPDs typically employs a donor-acceptor heterojunction structure with alternating energy levels. Typical donor materials include subphthalocyanine oligomers (SubPc) and copper phthalocyanine oligomers (CuPc), whose highest occupied molecular orbital (HOMO) energy level is typically around -5.6 eV and lowest unoccupied molecular orbital (LUMO) energy level is typically around -2.9 eV; typical acceptor materials include fullerenes (such as C... 60 C 70 (etc.), whose LUMO energy level is typically around -4.5 eV to -4.0 eV. The working principle of OPD includes the following steps: the material absorbs light to generate excitons, the excitons diffuse to the donor-acceptor interface, the excitons undergo charge separation at the interface, and the separated charges are transported and collected. To improve the exciton dissociation efficiency, donor and acceptor materials are usually mixed (co-deposited) to form a bulk heterojunction structure as the photosensitive layer. Accordingly, in existing OPD devices, the hole transport layer (HTL) uses a different material system than that of OLED devices, and the donor layer and HTL are designed with independent materials, with no material sharing between them.

[0035] However, in the above-mentioned integration scheme, OPD devices and OLED devices usually use their own independent functional layer material systems. There is a lack of material sharing and structural integration between the two, resulting in problems such as incompatible material systems, inability to share functional layers, and high process complexity.

[0036] To address the above-mentioned problems, the present invention provides a novel display panel, its manufacturing method, and a display device.

[0037] Specifically, in a first aspect, the present invention provides a display panel, such as Figure 1 and Figure 2 As shown, the display panel includes: substrate1; An organic electroluminescent display device 2 is disposed on the substrate 1. The organic electroluminescent display device 2 includes multiple pixel units arranged in an array and a hole transport layer 22, an electron transport layer 24 and a cathode 25 shared by all pixel units. Each pixel unit is provided with a first anode 21 and a light-emitting layer 23. An organic photodetector 3 is integrated into the pixel array layout area of ​​the organic electroluminescent display device 2; in: The organic photodetector 3 includes a second anode 31 and a photosensitive layer 33; the photosensitive layer 33 is made of a donor material and an acceptor material. The organic photodetector 3 shares the hole transport layer 22 of the organic electroluminescent display device 2; the donor material is the same as the material of the hole transport layer 22.

[0038] In this invention, the donor material of OPD and the hole transport material of OLED are the same material, and the two share the hole transport layer, thus avoiding the introduction of additional material systems and independent functional layers.

[0039] It should be noted that the terms "first anode" and "second anode" are used only for ease of distinction and should not be construed as indicating or implying relative importance or quantity. In this invention, the anode of the organic electroluminescent display device 2 is referred to as "first anode 21," and the anode of the organic photodetector 3 is referred to as "second anode 31." The first anode 21 and the second anode 31 are made of the same material (such as indium tin oxide) and formed synchronously through the same patterning process. However, they are physically independent of each other: the first anode 21 within each pixel unit is isolated from each other, and the second anode 31 is also isolated from the first anode 21 to meet the process requirements of anode patterning and achieve independent control of the OLED and OPD.

[0040] In this invention, the substrate 1 is made of glass, plastic, or a flexible substrate material. The flexible substrate material includes one or more of the following: polyimide (PI), polyethersulfone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyallylate, polycarbonate (PC), cellulose triacetate (TAC), cellulose acetate propionate (CAP), or acrylate (Acrylamide).

[0041] As a further preferred technical solution, such as Figure 1 As shown, the organic photodetector 3 shares the electron transport layer 24 of the organic electroluminescent display device 2. This shared film layer design can further reduce interface defects and leakage current, thereby improving device performance.

[0042] It should be noted that the electron transport layer of this invention is a conventional electron transport layer in the art. For example, the electron transport layer material can be BPhen (4,7-diphenyl-1,10-phenanthroline), BCP (copper bath), BAlq (bis(2-methyl-8-hydroxyquinoline-N1,O8)-(1,1'-biphenyl-4-hydroxy)aluminum), TmPyPB (1,3,5-tris(3-pyridyl-3-phenyl)benzene), Alq3 (8-hydroxyquinoline aluminum), etc. Taking BPhen as an example, its electron mobility is high, which can effectively transport electrons from the cathode to the photosensitive layer. Those skilled in the art can select appropriate electron transport layer materials according to the actual device requirements to achieve the technical effects of this invention.

[0043] As a further preferred technical solution, such as Figure 1 As shown, the organic photodetector 3 also shares the cathode 25 of the organic electroluminescent display device 2.

[0044] It should be noted that the cathode material of this invention is a conventional cathode material in the art. For example, the cathode material can be a magnesium-silver alloy (Mg:Ag), calcium (Ca), aluminum (Al), silver (Ag), or a multilayer composite structure thereof. Taking Mg:Ag alloy as an example, it has excellent electron injection characteristics, which is beneficial for electrons to be injected from the cathode into the electron transport layer. Those skilled in the art can select a suitable cathode material according to the actual device requirements to achieve the technical effects of this invention.

[0045] Preferably, the hole transport layer 22 has a highest occupied molecular orbital (HOMO) energy level of less than -5.6 eV and a lowest unoccupied molecular orbital (LUMO) energy level of less than -2.9 eV. Compared with the typical energy levels (HOMO≈-5.6 eV, LUMO≈-2.9 eV) of donor materials (such as SubPc / CuPc) in the prior art, the HTL material used in this invention has lower HOMO and LUMO energy levels. The inventors of this invention have discovered that by using an HTL material in this energy range in combination with a corresponding donor material, better photoelectric conversion efficiency and lower dark current can be obtained.

[0046] The principle is as follows: On the one hand, since the HOMO energy level of the donor layer is the same as that of the HTL and is higher than the barrier of the original donor layer (such as SubPc, HOMO≈-5.6eV), the dense thin film structure and the higher barrier can effectively block the leakage current of the anode from being injected into the active layer under reverse bias, thereby significantly reducing the dark current density; on the other hand, the LUMO energy level of the donor layer is the same as that of the HTL and is lower than the barrier of the original donor layer, which reduces the energy barrier when the hole moves towards the anode after exciton separation, thereby improving the external quantum efficiency (EQE).

[0047] In summary, this invention utilizes deeper HOMO energy levels to effectively suppress reverse leakage current and utilizes deeper LUMO energy levels to optimize charge transport, thereby simultaneously achieving low dark current and high external quantum efficiency.

[0048] It is understood that hole transport layer materials suitable for this invention include, but are not limited to, oCBP (2,2'-bis(9H-carbazole-9-yl)-1,1'-biphenyl), etc. Taking oCBP as an example, its HOMO energy level is -5.8 eV and its LUMO energy level is -3.0 eV. Those skilled in the art can select appropriate HTL materials according to the actual device requirements. As long as its energy level meets the range defined by this invention (HOMO < -5.6 eV, LUMO < -2.9 eV), the technical effects of this invention can be achieved.

[0049] It should be noted that, in this invention, the hole transport layer generally refers to one or more functional layers disposed between the anode and the light-emitting layer / photosensitive layer, used to provide hole transport functionality. In some specific embodiments of this invention, the hole transport layer may comprise a multilayer stacked structure of a hole injection layer (HIL) and a hole transport layer (HTL), for example, 2-TNATA (4,4',4''-tris(2-naphthylphenylamino)triphenylamine) as a hole injection layer and oCBP as a hole transport layer are sequentially disposed on the anode; in other embodiments of this invention, the hole transport layer may also be a single material layer, simultaneously possessing hole injection and hole transport functions, such as the oCBP layer used in Example 1. Those skilled in the art can select appropriate functional layer structures according to actual needs, as long as the HOMO and LUMO energy levels of the material meet the range defined by this invention, the technical effects of this invention can be achieved.

[0050] As an optional implementation, the second anode 31 is made of the same material as the first anode 21, but is physically formed independently to meet the process requirements of anode patterning.

[0051] It is understood that the anode materials suitable for this invention include, but are not limited to, the following transparent conductive materials: indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), etc. Among them, ITO is widely used due to its high light transmittance, low sheet resistance, and mature patterning process. Those skilled in the art can select appropriate anode materials according to the actual device requirements to achieve the technical effects of this invention.

[0052] In one specific embodiment of the present invention, the photosensitive layer 33 is a planar heterojunction structure, which is either one of the following two structures: (i) If Figure 3As shown, the donor layer 331 and the acceptor layer 332 are stacked sequentially; the donor layer 331 is in direct contact with the hole transport layer 22, and the acceptor layer 332 is in direct contact with the electron transport layer 24. This structure can form a heterojunction with a clear interface, which is beneficial for the effective separation of excitons. (ii) Only an acceptor layer 332 is provided, and at least a portion of the hole transport layer 22 also serves as a donor layer; the acceptor layer 332 is in direct contact with the hole transport layer 22, which also serves as a donor layer, and simultaneously, the acceptor layer 332 is in direct contact with the electron transport layer 24. This structure eliminates the need for a separate donor layer, simplifying the film structure and fabrication process, while also enabling the formation of a continuous and regular heterojunction interface, ensuring efficient exciton separation and charge transport.

[0053] In another specific embodiment of the present invention, such as Figure 4 As shown, the photosensitive layer 33 adopts a bulk heterojunction structure, which is formed by mixing donor and acceptor materials. The bulk heterojunction structure can increase the contact area between the donor and acceptor, shorten the exciton diffusion distance, and thus improve the external quantum efficiency of the device. In this invention, because the donor material and the hole transport layer material are selected from the same material, the donor material and the hole transport layer within the bulk heterojunction possess better energy level matching and interfacial contact characteristics, which can further improve charge extraction efficiency.

[0054] Furthermore, when HTL material is used as the donor material in this invention, its optical response band is wider than that of general OPD donor materials (such as SubPc / CuPc), which can cover a wider spectral range, thereby effectively improving the signal-to-noise ratio and enhancing recognition accuracy in the fingerprint recognition process.

[0055] It is understood that the receptor materials suitable for this invention include, but are not limited to, the following organic receptor materials: fullerenes and their derivatives (such as C...). 60 C 70 (etc.), non-fullerene acceptor materials. With C 60 For example, its LUMO energy level is relatively low, which allows for good energy level matching with the donor material and promotes exciton separation. Those skilled in the art can select appropriate acceptor materials according to the actual device requirements to achieve the technical effects of this invention.

[0056] This invention achieves material system compatibility and process integration between OPD and OLED by using the same donor material for the organic photodetector as the hole transport layer material for the organic electroluminescent display device. This design eliminates the need for additional donor material types and evaporation processes, simplifying the process and reducing manufacturing costs. Furthermore, since the donor layer directly uses materials for OLED organic electroluminescent evaporation, there is no need to develop or procure dedicated OPD donor materials, further reducing raw material costs.

[0057] Meanwhile, by setting the hole transport layer of the organic photodetector and the hole transport layer of the organic electroluminescent display device to the same material layer, and further optionally setting the electron transport layer and / or cathode to the same material layer, the film layer sharing between OPD and OLED is realized, avoiding the increase in thickness caused by setting two sets of functional layers separately, which is conducive to the thin and light design of terminal devices.

[0058] Regarding pixel layout, such as Figure 1 and Figure 2 , Figure 5 and Figure 6 As shown, the light-emitting layer 23 of each pixel unit includes a red light-emitting layer 231, a green light-emitting layer 232, and a blue light-emitting layer 233; the photosensitive layer 33 is arranged side by side with the red light-emitting layer 231, the green light-emitting layer 232, and the blue light-emitting layer 233 on the same layer. With this layout, the present invention achieves fingerprint recognition functionality across the entire display area, eliminating the need for users to press in a specific area and improving the user experience.

[0059] The materials for each luminescent layer can be selected from: organic small molecule fluorescent materials, organic polymer fluorescent materials, small molecule phosphorescent materials, or polymer phosphorescent materials. Each luminescent layer can be constructed in a host-guest doped or undoped manner, with a film thickness between 5 nm and 50 nm.

[0060] For example, in a specific embodiment of the present invention, the red light-emitting layer 231, the green light-emitting layer 232, and the blue light-emitting layer 233 all have a film thickness of 10 nm, and the materials are all in the form of host-guest doping. Wherein: The host material of the red luminescent layer 231 is CBP, and the guest material is bis(1-phenyl-isoquinoline)(acetylacetone)iridium(III) (Ir(piq)2(acac)): The host material of the green luminescent layer 232 is CBP, and the guest material is tris(2-phenylpyridine)iridium(III) (Ir(ppy)3); The main material of the blue luminescent layer 233 is 9,9'-(1,3-phenyl)bis-9H-carbazole (mCP), and the guest material is bis(4,6-difluorophenylpyridine-N,C2)pyridinecarboxyiridium(III) (FIrPic).

[0061] Preferably, multiple organic photodetectors 3 are arranged in an array to form a fingerprint recognition sensor array.

[0062] The organic photodetector 3 can be arranged in different ways according to layout requirements. For example, Figure 5 and Figure 6As shown in the figure, a single pixel unit and an organic photodetector 3 disposed between adjacent light-emitting layers within the pixel unit are illustrated. It should be noted that, to simplify the structure and highlight local layout relationships, the figure only shows one set of pixel units and their corresponding organic photodetectors, omitting the remaining pixel units and other similar devices in the pixel array. The organic photodetectors are actually disposed in the interlayer positions within the corresponding pixel units in the array.

[0063] For example, such as Figure 1 and Figure 2 As shown in the figure, a single pixel unit and an organic photodetector 3 disposed on its side are illustrated. It should be noted that the figure also uses a partial schematic representation, showing only a single group of pixels and the organic photodetector, omitting the remaining pixels and other organic photodetectors in the array. The organic photodetectors are actually arranged between adjacent pixel units. This type of partial arrangement has high space utilization and reduces interference with pixel illumination, balancing display and fingerprint detection performance.

[0064] In addition, the multiple organic photodetectors 3 can also be arranged in another way: arranged around the perimeter of each pixel unit. This circumferential arrangement allows for all-around light signal acquisition, improving fingerprint light sensitivity and recognition accuracy.

[0065] It should be understood that the above three arrangement forms can be used individually, or any two or three methods can be arranged in parallel. They can be flexibly combined and set according to the actual layout of the display panel and the light-sensing requirements. This invention does not impose any specific limitations.

[0066] In a second aspect, the present invention provides a method for manufacturing a display panel, please refer to... Figure 7 The preparation method includes the following steps: S1. Provide a substrate 1; S2. A first anode 21 of an organic electroluminescent display device 2 and a second anode 31 of an organic photodetector 3 are formed on the substrate 1. S3. A hole transport layer 22 is formed on the first anode 21 and the second anode 31. The hole transport layer 22 serves as both the hole transport layer of the organic electroluminescent display device 2 and the hole transport layer of the organic photodetector 3. S4. On the hole transport layer 22, a light-emitting layer 23 and a photosensitive layer 33 are formed in the region of the organic photodetector 3 in the region of the organic electroluminescent display device 2, respectively. The photosensitive layer 33 includes a donor material and an acceptor material, wherein the donor material is the same material as the hole transport layer 22. S5. An electron transport layer 24 for an organic electroluminescent display device 2 is formed on the light-emitting layer 23, and an electron transport layer for an organic photodetector 3 is formed on the photosensitive layer 33. S6. A cathode 25 of the organic electroluminescent display device 2 is formed on the electron transport layer 24 of the organic electroluminescent display device 2, and a cathode of the organic photodetector 3 is formed on the electron transport layer of the organic photodetector 3.

[0067] It should be noted that steps S1-S7 described above are merely the core preparation process of this invention and are not an exhaustive list of all preparation steps, nor do they constitute a strict limitation on the order of each step. Those skilled in the art will understand that in actual production, other conventional processes in the art may be included between or before / after the above steps. For example, ultrasonic cleaning and plasma treatment can be performed on the substrate before forming the anode; encapsulation can be performed after forming the cathode; and other conventional processes, etc. These conventional steps are all well-known technologies in the art, and their specific implementation does not affect the core inventive concept of this invention. For example, the encapsulation step can employ conventional encapsulation methods in the art, such as thin-film encapsulation, glass cover encapsulation, or metal cover encapsulation, to prevent water and oxygen from entering the display panel and ensure the stability of the device's operation. Those skilled in the art can choose whether to use these methods and what specific process parameters to use according to actual needs, all of which do not depart from the protection scope of this invention.

[0068] In the above preparation method, in order to simplify the overall preparation process and realize the reuse of film layers, the organic photodetector 3 can share the electron transport layer 24 of the organic electroluminescent display device 2, and is formed synchronously with the film layer of the display device through the same evaporation process.

[0069] Furthermore, the organic photodetector 3 shares the cathode 25 of the organic electroluminescent display device 2 and is formed synchronously through the same vapor deposition process, further reducing independent coating processes.

[0070] Meanwhile, the second anode 31 and the first anode 21 are formed simultaneously through the same patterning process. This structural design can simultaneously complete the fabrication of the display device anode and the photodetector anode without increasing the number of photomask layers, effectively simplifying the fabrication process and reducing production costs.

[0071] For the formation of the core photosensitive layer 33, this invention provides a variety of highly adaptable and flexible process solutions, which can be flexibly selected according to the device structure requirements. As one implementation scheme, when the photosensitive layer 33 is a planar heterojunction structure, the steps can be any one of the following two fabrication methods: (1) Donor material and acceptor material are sequentially deposited on the hole transport layer 22 to form a donor layer 331 and an acceptor layer 332, thereby constructing a complete planar heterojunction structure; or (2) Directly use at least a portion of the hole transport layer 22 as a donor layer, and deposit acceptor material only on the portion of the hole transport layer 22 that serves as the donor layer to form an acceptor layer, thereby completing the preparation of the photosensitive layer.

[0072] As another alternative preparation method, when the photosensitive layer 33 adopts a bulk heterojunction structure, it can be integrally formed by co-evaporation of the donor material and the acceptor material, which simplifies the process steps and ensures the uniformity of the bulk heterojunction film formation.

[0073] Furthermore, when the organic photodetectors 3 are multiple and arranged in an array to form a fingerprint recognition sensor array, all the organic photodetectors 3 can be synchronously aligned and fabricated with multiple pixel units of the organic electroluminescent display device 2, which greatly improves the device fabrication efficiency and meets the needs of large-scale mass production.

[0074] The preparation method of the present invention realizes the synergistic manufacturing of OPD and OLED, and simultaneously forms a common layer through the same evaporation process and simultaneously forms an anode through the same patterning process, thereby improving production efficiency and reducing manufacturing costs.

[0075] In a third aspect, the present invention provides a display device comprising the display panel described in the first aspect or the display panel prepared by the preparation method described in the second aspect.

[0076] The display device can be any electronic device that requires display and fingerprint recognition functions, such as a mobile phone, tablet, laptop, television, in-vehicle display, or wearable device.

[0077] The beneficial effects of the present invention will be further illustrated below through specific embodiments and comparative examples.

[0078] Example 1 This embodiment provides a display panel with the following structure: Component layout: In this embodiment, as Figure 1 As shown, the light-emitting layer 23 of each pixel unit includes a red light-emitting layer 231, a green light-emitting layer 232, and a blue light-emitting layer 233; the photosensitive layer 33 of the organic photodetector 3 is arranged side by side with the red light-emitting layer 231, the green light-emitting layer 232, and the blue light-emitting layer 233 on the same layer, that is, the organic photodetector 3 is also arranged in the same functional layer (the layer where the photosensitive layer 33 is located) on the substrate 1, and is integrated in the pixel array layout area of ​​the organic electroluminescent display device 2.

[0079] Specifically, such as Figure 1 and Figure 2As shown, the photosensitive layer 33 of the organic photodetector 3 is disposed on one side of the pixel unit, adjacent to and side by side with the pixel unit. The pixel unit is composed of a red light-emitting layer 231, a green light-emitting layer 232, and a blue light-emitting layer 233 arranged side by side. The photosensitive layer 33 of the organic photodetector 3 is located on one side of the pixel unit and is arranged side by side with the pixel unit.

[0080] Multiple organic photodetectors 3 are arranged in an array to cover the entire display area, forming a fingerprint recognition sensor array to achieve fingerprint recognition at any position on the full screen.

[0081] Layer structure and materials: Substrate 1: A glass substrate with a thickness of 0.5 mm is used.

[0082] First anode 21 and second anode 31: made of ITO with a thickness of 100 nm. First anode 21 and second anode 31 are formed simultaneously through the same patterning process, and although they are made of the same material, they are physically independent.

[0083] Hole transport layer 22: It adopts oCBP, with a HOMO energy level of -5.8eV, a LUMO energy level of -3.0eV, and a thickness of 40nm. This hole transport layer 22 serves as both the hole transport layer of the organic electroluminescent display device 2 and the hole transport layer of the organic photodetector 3, and the two share the same material layer.

[0084] The light-emitting layer 23 includes a red light-emitting layer 231, a green light-emitting layer 232, and a blue light-emitting layer 233, and is disposed only in the area of ​​the organic electroluminescent display device 2. Specifically: Red emitting layer 231: The host material is CBP, the guest material is Ir(piq)2(acac), the host-guest doping ratio is 4%, and the thickness is 10nm; Green luminescent layer 232: The host material is CBP, the guest material is Ir(ppy)3, the host-guest doping ratio is 6%, and the thickness is 10nm; Blue emitting layer 233: The host material is mCP, the guest material is FirPic, the host-guest doping ratio is 8%, and the thickness is 10nm.

[0085] Photosensitive layer 33: Employs a planar heterojunction structure. Donor layer 331 uses the same oCBP material as hole transport layer 22, with a thickness of 10 nm; acceptor layer 332 uses C... 60 The thickness is 30nm. It is only set in the region of the organic photodetector 3 (i.e., one side of the pixel unit, the region adjacent to and side by side with the pixel unit).

[0086] Electron transport layer 24: Utilizes BPhen with a thickness of 30 nm. This electron transport layer 24 serves as both the electron transport layer of the organic electroluminescent display device 2 and the electron transport layer of the organic photodetector 3, sharing the same material layer.

[0087] Cathode 25: Made of Mg:Ag alloy (mass ratio 1:9), with a thickness of 100 nm. This cathode 25 serves as both the cathode of the organic electroluminescent display device 2 and the cathode of the organic photodetector 3, sharing the same material layer.

[0088] The method for manufacturing the display panel in this embodiment includes the following steps: S1. Provide a glass substrate 1, clean and dry it.

[0089] S2. An anode pattern is formed on substrate 1 through photolithography and etching processes, thereby forming the first anode 21 of the organic electroluminescent display device 2 and the second anode 31 of the organic photodetector 3. The anode material is ITO with a thickness of 100 nm.

[0090] S3. A hole transport layer 22 is formed on the first anode 21 and the second anode 31 by vacuum evaporation. The evaporation rate is 0.1 nm / s and the thickness is 40 nm. The hole transport layer 22 is made of oCBP and serves as both the hole transport layer of the organic electroluminescent display device 2 and the hole transport layer of the organic photodetector 3.

[0091] S4. Using a fine metal mask (FMM), red, green, and blue emitting materials are sequentially deposited on the hole transport layer 22 in the regions of the organic electroluminescent display device 2 (i.e., the red, green, and blue sub-pixel regions) to form an emitting layer 23 with a total thickness of 30 nm. A photosensitive layer 33 is formed on the region of the organic photodetector 3 (i.e., one side of the pixel unit, adjacent to the pixel unit): first, a donor layer 331 is deposited, with the donor material being oCBP (the same as the hole transport layer 22), and a thickness of 10 nm; then, an acceptor layer 332 is deposited, with the acceptor material being C... 60 The thickness is 30 nm; a photosensitive layer 33 with a planar heterojunction structure is formed.

[0092] S5. An electron transport layer 24 is formed on the light-emitting layer 23 and the photosensitive layer 33 by vacuum evaporation. The evaporation rate is 0.1 nm / s, and the thickness is 30 nm. The electron transport layer 24 is made of BPhen and serves as both the electron transport layer of the organic electroluminescent display device 2 and the electron transport layer of the organic photodetector 3.

[0093] S6. A cathode is formed on the electron transport layer 24 by vacuum evaporation. The evaporation rate is 0.2 nm / s, and the thickness is 100 nm. The cathode material is a Mg:Ag alloy (mass ratio 1:9), which also serves as the cathode 25 of the organic electroluminescent display device 2 and the cathode of the organic photodetector 3.

[0094] S7. Perform encapsulation to complete the fabrication of the display panel.

[0095] Comparative Example 1 This comparative example provides a conventional display panel and its preparation method. The only difference between this example and Example 1 is that the donor material of the photosensitive layer 33 of the organic photodetector 3 is different. It is SubPc, with a HOMO energy level of -5.6 eV and a LUMO energy level of -2.9 eV.

[0096] Apart from the differences mentioned above, the other structures and preparation steps of this comparative example are the same as those in Example 1, and will not be repeated here.

[0097] Experimental Example 1 This test case investigated the performance of the display panels prepared in Example 1 and Comparative Example 1. The only difference between Example 1 and Comparative Example 1 is that the donor material for OPD in Example 1 is oCBP (the same as HTL), while the donor material for OPD in Comparative Example 1 is SubPc (different from HTL). The other structures and fabrication processes of the two display panels are exactly the same.

[0098] Test Methods: The display panels prepared according to Example 1 and Comparative Example 1 were subjected to performance tests on the OPD devices under the same test conditions. Specific test conditions were as follows: room temperature (25℃), using a 530nm LED light source, and a Keithley 4200 semiconductor parameter analyzer. Dark current density was tested under no-light conditions, and under illumination of 1mW / cm². 2 External quantum efficiency (EQE) was tested under the following conditions. All tests were conducted in a standard atmospheric environment with a relative humidity of <30%, and the samples were stabilized in a dark chamber for 30 minutes before testing.

[0099] First, the light absorption characteristics of SubPc, the conventional donor material used in Comparative Example 1, were tested. Figure 8 This is the UV-Vis absorption spectrum of the donor material (SubPc) in Comparative Example 1. From... Figure 8 It can be seen that the absorption peak of the SubPc material is located around 600nm, with strong absorption of orange-red light, but weak absorption of blue light (450-480nm) and green light (550nm). This uneven absorption characteristic limits the performance of traditional OPD devices in full-spectrum fingerprint recognition.

[0100] In contrast, the OPD device prepared in Example 1 of this invention exhibits superior spectral response characteristics. Figure 9 The images show the external quantum efficiency (EQE) spectra of the OPD device prepared in Example 1 of this invention under different bias voltages. Figure 9 It can be seen that the device has a peak external quantum efficiency of about 76% in the 520-560nm band (green light band) and maintains an external quantum efficiency of more than 70% in the 400-600nm visible light band, indicating that the device of the present invention has a wide spectral response and high photoelectric conversion efficiency.

[0101] Furthermore, the dark current characteristics of the OPD device prepared in Embodiment 1 of the present invention were tested. Figure 10 This is a current density-voltage (JV) characteristic curve of the OPD device prepared in Embodiment 1 of the present invention. From... Figure 10 It can be seen that within the reverse bias range of -1V to -2V, the device's dark current density remains at 1×10⁻⁶. -8 A / cm 2 The following extremely low levels are even lower, reaching 1×10 at near-zero bias. -11 A / cm 2 This is attributed to the higher potential barrier resulting from the use of the same donor material as HTL in this invention, which effectively blocks reverse leakage current.

[0102] To further quantify the performance differences between Example 1 and Comparative Example 1, key performance indicators of the two display panels were summarized, and the test results are shown in Table 1: Table 1. Performance Comparison of Different Display Panels The test results above show that, compared with OPD devices using traditional donor materials, the OPD device using the technical solution of this invention significantly improves both the dark current density and external quantum efficiency, two key performance indicators. Specifically, the dark current density is reduced by nearly two orders of magnitude, and the external quantum efficiency is improved by approximately 13 percentage points. This fully demonstrates that by unifying the donor material of the OPD with the hole transport layer material of the OLED and achieving functional layer sharing, this invention not only solves the process compatibility issues of existing technologies but also significantly improves the performance of the device.

[0103] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A display panel, characterized in that, include: substrate(1); An organic electroluminescent display device (2) is disposed on the substrate (1). The organic electroluminescent display device (2) includes multiple pixel units arranged in an array and a hole transport layer (22), an electron transport layer (24) and a cathode (25) shared by all pixel units. Each pixel unit is provided with a first anode (21) and a light-emitting layer (23). An organic photodetector (3) is integrated into the pixel array layout area of ​​the organic electroluminescent display device (2); in: The organic photodetector (3) includes a second anode (31) and a photosensitive layer (33); the material of the photosensitive layer (33) includes a donor material and an acceptor material; The organic photodetector (3) shares the hole transport layer (22) of the organic electroluminescent display device (2); the donor material is the same as the material of the hole transport layer (22).

2. The display panel according to claim 1, characterized in that, The organic photodetector (3) shares the electron transport layer (24) of the organic electroluminescent display device (2).

3. The display panel according to claim 1 or 2, characterized in that, The organic photodetector (3) shares the cathode (25) of the organic electroluminescent display device (2).

4. The display panel according to claim 3, characterized in that, The hole transport layer (22) has a highest occupied molecular orbital energy level of less than -5.6 eV and a lowest unoccupied molecular orbital energy level of less than -2.9 eV.

5. The display panel according to claim 1, characterized in that, The second anode (31) is made of the same material as the first anode (21).

6. The display panel according to claim 4, characterized in that, The photosensitive layer (33) is a planar heterojunction structure; the planar heterojunction structure is any one of the following two structures: (i) A donor layer (331) and a acceptor layer (332) are stacked sequentially, wherein the donor layer (331) is in direct contact with the hole transport layer (22), and the acceptor layer (332) is in direct contact with the electron transport layer (24); or (ii) Receptor layer (332), at least a portion of the hole transport layer (22) serves as a donor layer, the receptor layer (332) is in direct contact with the hole transport layer (22) serving as a donor layer, and the receptor layer (332) is in direct contact with the electron transport layer (24).

7. The display panel according to claim 4, characterized in that, The photosensitive layer (33) is a bulk heterojunction structure; the bulk heterojunction structure contains a mixture of the donor material and the acceptor material.

8. The display panel according to claim 1, characterized in that, Each pixel unit has a light-emitting layer (23) including a red light-emitting layer (231), a green light-emitting layer (232) and a blue light-emitting layer (233); the photosensitive layer (33) is arranged side by side with the red light-emitting layer (231), the green light-emitting layer (232) and the blue light-emitting layer (233) on the same layer.

9. The display panel according to claim 8, characterized in that, The organic photodetector (3) is provided in multiple arrays to form a fingerprint recognition sensor array.

10. The display panel according to claim 9, characterized in that, The arrangement of the plurality of organic photodetectors (3) includes at least one of the following: It is embedded between adjacent light-emitting layers inside the pixel unit, arranged between adjacent pixel units, and arranged around the periphery of the pixel unit.

11. A method for manufacturing a display panel, characterized in that, Includes the following steps: Provide a substrate (1); A first anode (21) of an organic electroluminescent display device (2) and a second anode (31) of an organic photodetector (3) are formed on the substrate (1). Hole transport layer (22) is formed on the first anode (21) and the second anode (31), and the hole transport layer (22) serves as both the hole transport layer of the organic electroluminescent display device (2) and the hole transport layer of the organic photodetector (3). On the hole transport layer (22), a light-emitting layer (23) and a photosensitive layer (33) are formed in the regions of the organic electroluminescent display device (2) and the organic photodetector (3), respectively; the photosensitive layer (33) includes a donor material and an acceptor material, wherein the donor material is the same material as the hole transport layer (22); An electron transport layer (24) of an organic electroluminescent display device (2) is formed on the light-emitting layer (23), and an electron transport layer of an organic photodetector (3) is formed on the photosensitive layer (33); A cathode (25) of the organic electroluminescent display device (2) is formed on the electron transport layer (24) of the organic electroluminescent display device (2), and a cathode of the organic photodetector (3) is formed on the electron transport layer of the organic photodetector (3).

12. The preparation method according to claim 11, characterized in that, The organic photodetector (3) shares the electron transport layer (24) of the organic electroluminescent display device (2) and is formed synchronously through the same vapor deposition process.

13. The preparation method according to claim 11 or 12, characterized in that, The organic photodetector (3) shares the cathode (25) of the organic electroluminescent display device (2) and is formed synchronously through the same vapor deposition process.

14. The preparation method according to claim 13, characterized in that, The second anode (31) and the first anode (21) are formed simultaneously through the same patterning process.

15. The preparation method according to claim 11, characterized in that, When the photosensitive layer (33) adopts a planar heterojunction structure, the preparation steps can be carried out by any one of the following two methods: (1) Donor material and acceptor material are sequentially deposited on the hole transport layer (22) to form a donor layer (331) and an acceptor layer (332); or (2) At least a portion of the hole transport layer (22) is used as a donor layer, and acceptor material is deposited on the portion of the hole transport layer (22) used as the donor layer to form an acceptor layer; When the photosensitive layer (33) adopts a bulk heterojunction structure, the steps are: co-evaporation including a mixture of donor material and acceptor material.

16. The preparation method according to claim 15, characterized in that, The organic photodetectors (3) are multiple and arranged in an array to form a fingerprint recognition sensor array; the photosensitive layer (33) of the multiple organic photodetectors (3) is prepared synchronously with the multiple pixel units of the organic electroluminescent display device (2).

17. A display device, characterized in that, The display device includes the display panel according to any one of claims 1-10 or the display panel prepared by the preparation method according to any one of claims 11-16.

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