Preparation method of display panel, display panel and display device

Abstract

The invention provides a preparation method of a display panel, the display panel and a display device.The display panel comprises a substrate, a photoelectric detector and an organic electroluminescent device, the photoelectric detector and the organic electroluminescent device are arranged on one side of the substrate, and the photoelectric detector comprises an active layer and a first hole transport layer arranged on one side of the active layer; the organic electroluminescent device comprises a second hole transport layer, the first hole transport layer and the second hole transport layer are arranged on the same layer, the active layer is a doped layer of an acceptor material and a donor material, the dielectric constant range of the acceptor material is 4.4-5.1, and the dielectric constant range of the donor material is 4.4-5.1. The ratio of the mass of the acceptor material to the sum of the mass of the acceptor material and the mass of the donor material is 60%-95%.

Description

Technical Field

[0001] This disclosure relates to the field of display technology. More specifically, it relates to a method for manufacturing a display panel, a display panel, and a display device. Background Technology

[0002] With the widespread adoption of smartphones and other mobile devices, users' demands for device security and convenience are increasing, making under-display optical fingerprint recognition technology the mainstream solution. This technology typically utilizes a photodetector integrated under the phone screen to receive the screen's light-emitting signals reflected by the user's finger, thereby achieving fingerprint imaging and recognition. Meanwhile, Organic Light Emitting Diode (OLED) displays, with their advantages of self-illumination, high contrast, wide viewing angle, and flexibility, have been widely used in high-end mobile phone screens.

[0003] When implementing fingerprint recognition in an OLED screen, integrating the OLED display function with the under-display photoelectric detection function helps reduce production costs and improve production efficiency. Traditional integration solutions typically design the hole transport layer (HTL) of the photoelectric detector and the corresponding functional layer of the OLED display device to use the same materials and structure for sharing.

[0004] However, the aforementioned shared design leads to problems such as excessively high dark current density (Jdark) and low external quantum efficiency (EQE) in the photodetector within the screen. Summary of the Invention

[0005] The purpose of this disclosure is to provide a method for manufacturing a display panel, a display panel, and a display device to solve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, the present disclosure adopts the following technical solution: The first aspect of this disclosure provides a display panel, including a substrate and a photodetector and an organic electroluminescent device disposed on one side of the substrate. The photodetector includes an active layer and a first hole transport layer disposed on one side of the active layer. The organic electroluminescent device includes a second hole transport layer. The first hole transport layer and the second hole transport layer are disposed in the same layer. The active layer is a doped layer of acceptor material and donor material. The dielectric constant of the acceptor material is in the range of 4.4 to 5.1. The ratio of the mass of the acceptor material to the sum of the masses of the acceptor material and the donor material is 60% to 95%.

[0007] Optionally, the band gap width of the donor material is in the range of 3.1 eV to 3.5 eV.

[0008] Optionally, the donor material is TAPC or NPB, and the acceptor material is C. 60 Or C 70 .

[0009] Optionally, the ratio of the mass of the receptor material to the sum of the masses of the receptor material and the donor material is 60-80%.

[0010] Optionally, the thickness of the active layer is 30-500 nanometers.

[0011] Optionally, the material of the first hole transport layer is HT002 or TAPC.

[0012] Optionally, the photodetector further includes a first electrode layer, a first electron transport layer, and a second electrode layer, wherein the first electrode layer, the first hole transport layer, the active layer, the first electron transport layer, and the second electrode layer are stacked sequentially. The organic electroluminescent device further includes a third electrode layer, a light-emitting layer, a second electron transport layer, and a fourth electrode layer, wherein the third electrode layer, the second hole transport layer, the light-emitting layer, the second electron transport layer, and the fourth electrode layer are stacked sequentially. The third electrode layer is disposed in the same layer as the first electrode layer, the second electron transport layer is disposed in the same layer as the first electron transport layer, and the fourth electrode layer is disposed in the same layer as the second electrode layer.

[0013] Optionally, the area of ​​the overlapping region between the orthographic projection of the first electrode layer on the substrate and the orthographic projection of the second electrode layer on the substrate is 6 to 10 square millimeters.

[0014] A second aspect of this disclosure provides a method for manufacturing a display panel, comprising the following steps: Provide substrates; A photodetector and an organic electroluminescent device are formed on one side of the substrate. The photodetector includes an active layer and a first hole transport layer disposed on one side of the active layer. The organic electroluminescent device includes a second hole transport layer. The first hole transport layer and the second hole transport layer are disposed in the same layer. The active layer is a doped layer of acceptor material and donor material. The dielectric constant of the acceptor material is in the range of 4.4 to 5.1, and the mass ratio of the acceptor material is 60% to 95%.

[0015] A third aspect of this disclosure provides a display device including a display panel as described above.

[0016] The beneficial effects of this disclosure are as follows: The display panel of this disclosure, by introducing a high-doped, high-dielectric-constant acceptor material into the active layer, can not only improve the exciton dissociation efficiency and the external quantum efficiency (EQE), but also reduce the charge-transfer state exciton density at the donor-acceptor interface, thereby reducing the dark-state current density (Jdark) of the photodetector. In other words, the display panel of this disclosure can achieve a lower dark-state current density (Jdark) and a higher external quantum efficiency (EQE) under high bias conditions while sharing the hole transport layer between the photodetector and the OLED display device to reduce production costs. Attached Figure Description

[0017] The specific embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the structure of an embodiment of the display panel provided in this disclosure; Figure 2 The materials provided in this disclosure, TAPC, C 70 And a structural diagram of BCP; Figure 3 This is a schematic diagram of another embodiment of the display panel provided in this disclosure; Figure 4 A flowchart illustrating an embodiment of the method for manufacturing a display panel provided in this disclosure; Figure 5 In a specific example, the receptor material C 70 The curves showing the relationship between external quantum efficiency and bias voltage when the mass ratios are 60%, 70%, and 80%, respectively; Figure 6 Here is a curve showing the relationship between the external quantum efficiency of a photodetector and wavelength in another specific example; Figure 7 for Figure 6 The example shown illustrates the relationship between the external quantum efficiency and wavelength of the photodetector at a bias voltage of -3V. Figure 8 for Figure 6 The example shown is a curve showing the relationship between the dark-state current density and the bias voltage of the photodetector. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0020] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “including,” “comprising,” or “containing,” and similar terms mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” and “right,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0021] Organic photodetectors (OPDs), as optoelectronic devices based on organic semiconductor materials, possess advantages such as light weight, high flexibility, and large-area fabrication, showing broad application prospects in imaging, spectral analysis, and biosensing. Their core working principle involves the absorption of photons and the generation of excitons through an organic active layer. These excitons dissociate into free carriers (electrons and holes) at the donor-acceptor interface, which are then collected by electrodes to form a photocurrent. The external quantum efficiency (EQE) is a key indicator of the device's ability to convert incident photons into photocurrent, while the dark-state current density (Jdark) reflects the device's noise floor level under illumination conditions.

[0022] In related technologies, sharing the hole transport layer of an organic photodetector with the hole transport layer of an OLED display device leads to a deterioration in two key performance indicators: dark-state current density Jdark and external quantum efficiency EQE. This is mainly manifested in the following ways: Firstly, sharing a hole transport layer may cause the material or interface properties of this layer to be unable to optimally match the stringent requirements of the photodetector for low leakage current, thereby significantly increasing the dark state current density. Excessive dark state current density will directly raise the noise floor of the detector, resulting in a decrease in the signal-to-noise ratio of the final fingerprint image, which seriously affects the accuracy and reliability of fingerprint recognition.

[0023] Secondly, sharing a hole transport layer may alter the charge transport balance and recombination dynamics within the active layer of the photodetector. For example, it may hinder the effective separation and extraction of photogenerated carriers, leading to a reduction in external quantum efficiency. The direct consequence of this reduced efficiency is insufficient response of the photodetector to weak fingerprint reflection signals, resulting in weak imaging signal intensity, poor image contrast, and ultimately limiting the performance of the fingerprint recognition system.

[0024] Therefore, how to effectively control the dark current density Jdark and improve the external quantum efficiency EQE while realizing the sharing of hole transport layer between photodetectors and OLED display devices to reduce production costs has become a technical problem that urgently needs to be solved in the field of terminal screen fingerprint imaging technology. However, under the working condition of applying high bias voltage, it is difficult to achieve both high external quantum efficiency EQE and low dark current density Jdark at the same time. This contradiction is mainly due to the following reasons: (1) Energy level mismatch and interface recombination: In traditional photodetectors, the energy level arrangement of donor and acceptor materials is often not optimal, resulting in low carrier transport efficiency and easy formation of recombination centers at the interface, which significantly increases the dark current. For example, although acceptor materials based on fullerene derivatives have high electron mobility, their low LUMO energy level may cause electrons to leak back to the anode, becoming the main source of dark current. One of the sources; (2) Dark current contribution of charge-transferred state excitons. Under high bias, the charge-transferred state excitons formed at the acceptor interface have low binding energy and are easily dissociated by thermal excitation to generate free carriers and directly contribute to the dark current. This phenomenon is particularly prominent in material systems with narrow band gaps or low CT state binding energy, which directly leads to a sharp deterioration in the signal-to-noise ratio of the device under high bias; (3) Recombination and tunneling induced by interface defects: There are a large number of defects at the interface between the organic active layer and the electrode. These defects, as carrier trapping centers, will significantly promote non-radiative recombination. At the same time, under high bias, these defects may also become channels for carrier tunneling, which together lead to an uncontrollable increase in dark current.

[0025] To address the aforementioned technical problems, this disclosure provides a method for manufacturing a display panel, a display panel, and a display device. For example, please refer to... Figure 1 , Figure 1 This is a schematic diagram of the structure of an embodiment of the display panel provided in this disclosure, as shown below. Figure 1 As shown, the display panel includes a substrate 10 and a photodetector 20 and an organic electroluminescent device disposed on one side of the substrate 10. The photodetector 20 includes an active layer 210 and a first hole transport layer 220 disposed on one side of the active layer 210. The organic electroluminescent device includes a second hole transport layer. The first hole transport layer 220 and the second hole transport layer are disposed in the same layer. The active layer 210 is a doped layer of acceptor material and donor material. The dielectric constant of the acceptor material is in the range of 4.4 to 5.1, and the ratio of the mass of the acceptor material to the sum of the masses of the acceptor material and the donor material is 60% to 95%.

[0026] The substrate 10 is a transparent substrate, which can be a flexible substrate made of materials such as polyimide (PI), polyethylene naphthalate (PEN), or thermoplastic polyester (PET), or a rigid substrate made of materials such as glass or quartz.

[0027] The active layer 210 is a key region directly involved in photon absorption, exciton generation, exciton separation, and charge collection. To achieve efficient photoelectric conversion, the active layer is typically composed of an acceptor material and a donor material. The donor material is responsible for absorbing photons to generate excitons and providing a hole transport channel. The highest occupied molecular orbital (HOMO) energy level of the donor material is relatively high, facilitating the movement of holes to the electrode. The acceptor material is responsible for receiving electrons from the donor, forming an electron transport channel. The lowest unoccupied molecular orbital (LUMO) energy level of the acceptor material is relatively low, facilitating the transition of electrons from the donor to the electrode. In other words, the donor material provides a hole transport channel, and the acceptor material provides an electron transport channel. The two materials contact each other in the active layer to form a charge separation interface.

[0028] In this embodiment of the disclosure, the dielectric constant of the acceptor material is in the range of 4.4 to 5.1, that is, the dielectric constant of the acceptor material is greater than or equal to 4.4 and less than or equal to 5.1.

[0029] Optionally, the receptor material is C 60 Or C 70 Among them, C 60 The dielectric constant is 4.4, C 70 The dielectric constant is 5.1. It is understandable that the acceptor material can also be other materials with a dielectric constant in the range of 4.4 to 5.1.

[0030] For example, the receptor material is C 70 C 70 Composed of 70 carbon atoms, its structure resembles a rugby ball or an elongated ellipsoid, consisting of 12 pentagons and 25 hexagons. A schematic diagram of its structure is shown below. Figure 2 As shown.

[0031] The ratio of the mass of the acceptor material to the sum of the masses of the acceptor material and the donor material is also known as the acceptor material mass ratio. The larger the mass ratio, the higher the doping concentration of the acceptor material in the active layer 210. For example, if the acceptor material mass ratio is 60% to 95%, it means that the acceptor material is the main component in the active layer 210 and has a higher doping concentration than the donor material.

[0032] Optionally, the ratio of the mass of the acceptor material to the sum of the masses of the acceptor material and the donor material is 60% to 80%.

[0033] For example, the mass ratio of the acceptor material is 60% and the mass ratio of the donor material is 40%.

[0034] For example, the mass ratio of the acceptor material is 70% and the mass ratio of the donor material is 30%.

[0035] For example, the mass ratio of the acceptor material is 80% and the mass ratio of the donor material is 20%.

[0036] The first hole transport layer 220 and the second hole transport layer are set in the same layer, which can be understood as the photodetector 20 and the organic electroluminescent device sharing the hole transport layer.

[0037] The display panel of this disclosure has the following advantages: On the one hand, the active layer 210 uses the aforementioned acceptor material with a high dielectric constant (ranging from 4.4 to 5.1) and is doped at a high concentration (mass ratio of 60% to 95%). This allows full utilization of the polarization effect of the acceptor material. This polarization effect significantly reduces the exciton binding energy, enabling excitons generated at the acceptor interface to dissociate into free charges (electrons and holes) more efficiently. The increased exciton dissociation efficiency directly increases the number of charge carriers that can be collected and used for photoelectric conversion, thereby significantly improving the external quantum efficiency (EQE) of organic photodetectors. In practical applications, such as fingerprint imaging technology for mobile phone screens, a higher EQE allows the photodetector 20 to more sensitively capture the weak light reflected from the fingerprint, improving the clarity and recognition accuracy of the fingerprint image.

[0038] On the other hand, employing a high doping concentration in the acceptor material of the active layer, as shown above, not only promotes efficient exciton dissociation but also reduces the charge-transfer exciton density at the acceptor interface. This reduction in charge-transfer exciton density effectively suppresses thermally excited dissociation, a significant cause of dark current generation. Therefore, suppressing this process significantly reduces the current density of the photodetector under dark conditions, thus minimizing noise interference. In fingerprint imaging applications, a lower dark-state current density helps improve the signal-to-noise ratio of fingerprint images, enabling fingerprint recognition systems to more accurately distinguish fingerprint features and reduce false acceptance and false rejection rates.

[0039] In one possible implementation, such as Figure 1 and Figure 3As shown, the photodetector 20 further includes a first electrode layer 230, a first electron transport layer 240, and a second electrode layer 250. The first electrode layer 230, the first hole transport layer 220, the active layer 210, the first electron transport layer 240, and the second electrode layer 250 are stacked sequentially. The organic electroluminescent device further includes a third electrode layer 330, a light-emitting layer 310, a second electron transport layer, and a fourth electrode layer. The third electrode layer 330, the second hole transport layer, the light-emitting layer 310, the second electron transport layer, and the fourth electrode layer are stacked sequentially. The third electrode layer 330 is co-layered with the first electrode layer 230, the second electron transport layer is co-layered with the first electron transport layer 240, and the fourth electrode layer is co-layered with the second electrode layer.

[0040] In this design, one of the first electrode layer 220 and the second electrode layer 250 is an anode layer, and the other is a cathode layer. In a specific example, the first electrode layer 220 is an anode layer, and the second electrode layer 250 is a cathode layer. The anode layer is made of indium tin oxide (ITO) with a work function between 4.7 eV and 5.2 eV. The first hole transport layer 220 is made of HT002, a commercially available OLED hole transport material. The active layer 210 consists of a donor material TAPC and an acceptor material C. 70 The doped layer is formed; the first electron transport layer 240 is made of BCP, where BCP is expressed in Chinese as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; the second electrode layer 250 is a metal electrode formed of aluminum or other metals.

[0041] In this disclosure, unless otherwise stated, the term "co-layer arrangement" means that two layers, components, members, elements, or portions can be formed by the same fabrication process (e.g., patterning process), and that the two layers, components, members, elements, or portions are generally formed of the same material. For example, co-layer arrangement of two or more functional layers means that these co-layer functional layers can be formed using the same material layer and the same fabrication process, thereby simplifying the fabrication process of the display substrate.

[0042] In addition, such as Figure 3 As shown, the display panel also includes a driving circuit layer 40 disposed between the substrate 10 and the photodetector 20, a pixel defining layer 50 formed on the driving circuit layer 40, an encapsulation layer (TFE) 60 covering the photodetector 20 and the organic electroluminescent device, and a cover plate layer 70 disposed on the side of the encapsulation layer 60 away from the substrate 10.

[0043] In one specific example, the driving circuit layer 40 includes an active layer 410, a gate insulating layer (GI) 420 covering the active layer 410, a gate layer 430 formed on the gate insulating layer 420, a dielectric layer (ILD) 440 covering the gate layer 430, a source drain metal layer (SD) 450 formed on the dielectric layer 440, and a planarization layer 460 covering the source drain metal layer 450, which are sequentially stacked on the substrate 10.

[0044] In one possible implementation, the band gap width of the donor material is in the range of 3.1 eV to 3.5 eV, that is, the band gap width of the donor material is greater than or equal to 3.1 eV and less than or equal to 3.5 eV.

[0045] The band gap refers to the energy difference between the highest energy level of the valence band (i.e., the highest occupied molecular orbital HOMO) and the lowest energy level of the conduction band (i.e., LUMO) in the electronic band structure. This energy difference determines the minimum energy required for an electron to transition from the valence band to the conduction band, and is also a key parameter for the material's light absorption, electrical conductivity, and photoelectric properties. The unit is usually electron volt (eV).

[0046] Optionally, the donor material is TAPC or NPB, wherein TAPC is expressed in Chinese as 1,1-bis[di(4-methylphenyl)aminophenyl]cyclohexane, and its molecular structure is as follows: Figure 2 As shown, the Chinese expression for NPB is N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine.

[0047] In some embodiments, the donor material is NPB, with the highest occupied molecular orbital HOMO = 5.5 eV, the lowest occupied molecular orbital LUMO = 2.4 eV, and the band gap width Eg = 3.1 eV.

[0048] In some embodiments, the donor material is TAPC, with the highest occupied molecular orbital HOMO = 5.5 eV, the lowest occupied molecular orbital LUMO = 2.0 eV, and the band gap width Eg = 3.5 eV.

[0049] It is understood that, in other embodiments, the donor material may also be other materials with a band gap width in the range of 3.1 eV to 3.5 eV.

[0050] In a specific example, the donor material of the active layer 210 is TAPC, and the acceptor material is C. 60 .

[0051] In a specific example, the donor material of the active layer 210 is NPB, and the acceptor material is C. 60 .

[0052] In a specific example, the donor material of the active layer 210 is TAPC, and the acceptor material is C. 70 .

[0053] In a specific example, the donor material of the active layer 210 is NPB, and the acceptor material is C. 70 .

[0054] In this embodiment of the disclosure, a donor material with a wide bandgap (bandgap width of 3.1 eV to 3.5 eV) and the above-mentioned acceptor material are used as the active layer 210, which has the following advantages: On the one hand, the HOMO energy level of the wide-bandgap donor material matches the other energy level structures in the active layer 210, which is conducive to the collection of photogenerated charges. After the photogenerated charges are generated, they can be collected by the electrodes more smoothly, reducing the recombination and loss of charges inside the device, and further improving the external quantum efficiency (EQE). This enables the photodetector to detect weak light signal changes more accurately in high-sensitivity photodetector applications (such as biosensing, environmental monitoring, etc.).

[0055] On the other hand, using wide-bandgap donor and acceptor materials as active layers increases the bandgap of charge-transferred excitons. The increased bandgap requires higher energy for thermally excited dissociation of charge-transferred excitons, thereby further suppressing the dark current contribution caused by thermally excited dissociation. This dual suppression mechanism, together with the suppression of thermally excited dissociation brought about by the acceptor material, reduces the dark current density Jdark of the photodetector, improves the stability and reliability of the device under low-light or no-light conditions, and is suitable for precision photodetection fields with strict requirements for dark current.

[0056] The display panel of this disclosure uses a wide-bandgap donor material and a highly doped, high-dielectric-constant acceptor material as the active layer, which can improve the external quantum efficiency (EQE) and reduce the dark-state current density (Jdark). On this basis, it can also broaden the operating condition range of the photodetector, enabling the photodetector to maintain good performance under high bias conditions. It can efficiently respond to optical signals and effectively control dark current, avoiding performance degradation caused by high bias. This allows the device to work stably and reliably in different working environments and usage scenarios, improving the device's versatility and adaptability.

[0057] In some embodiments, the material of the first hole transport layer is HT002 or TAPC.

[0058] HT002 is the code name for the hole transport layer material used in commercial OLEDs.

[0059] In this embodiment, the highest occupied molecular orbital (HOMO) energy level of the donor material in the active layer is relatively high. Because it is compatible with more hole transport layer materials, the hole transport layer materials can be shared, providing more options for device fabrication.

[0060] In some embodiments, the thickness of the active layer is 30-500 nanometers.

[0061] The inventors discovered that the thickness of the active layer also affects the external quantum efficiency (EQE) and the dark-state current density (Jdark). Specifically, increasing the active layer thickness enhances light absorption, which helps improve the EQE. However, increased thickness weakens the internal electric field of the device, thereby reducing both the EQE and the dark-state current density (Jdark). Furthermore, the inventors found that when the thickness of the active layer is in the range of tens to hundreds of nanometers and generally does not exceed 500 nanometers, it is possible to simultaneously achieve a relatively good EQE and dark-state current density (Jdark).

[0062] For example, the thickness of the active layer is 30nm, 50nm, 100nm, 150nm, 180nm, 200nm, 300nm, 400nm or 500nm.

[0063] In one possible implementation, the area of ​​the overlapping region between the orthographic projection of the first electrode layer 220 on the substrate 10 and the orthographic projection of the second electrode layer 250 on the substrate 10 is 6 to 10 square millimeters. For example, the area of ​​the effective detection region is 6 square millimeters, 7 square millimeters, 8 square millimeters, 9 square millimeters, or 10 square millimeters.

[0064] In this embodiment, the first electrode layer 220 is an anode layer, which is a patterned anode electrode. For example, the first electrode layer 220 includes a plurality of spaced-apart thin strip-shaped first sub-electrodes. The second electrode layer 250 may also include a plurality of thin strip-shaped second sub-electrodes. The intersection of the first electrode layer 220 and the second electrode layer 250 is the effective detection area. When light shines on the active layer, electron-hole pairs are generated. Because the distance between the anode and cathode electrode strips is very close (typically on the order of micrometers or nanometers), under the action of the electric field between the electrodes, holes are collected by adjacent anode strips, and electrons are collected by adjacent cathode strips, thereby forming a photocurrent and achieving photoelectric detection.

[0065] Based on the same inventive concept, the second aspect of this disclosure provides a method for manufacturing a display panel, such as... Figure 4 As shown, it includes the following steps: Step S101: Provide a substrate. In step S102, a photodetector and an organic electroluminescent device are formed on one side of the substrate. The photodetector includes an active layer and a first hole transport layer disposed on one side of the active layer. The organic electroluminescent device includes a second hole transport layer. The first hole transport layer and the second hole transport layer are disposed in the same layer. The active layer is a doped layer of acceptor material and donor material. The dielectric constant of the acceptor material is in the range of 4.4 to 5.1, and the mass ratio of the acceptor material is 60% to 95%.

[0066] In a specific example, the step of forming a photodetector on one side of the substrate includes: Step S201: A patterned first electrode layer is formed on one side of the substrate. In specific implementation, an indium tin oxide layer is first deposited on the substrate, and then the ITO layer is patterned using a photolithography process to form a first sub-electrode in the form of spaced fine strips.

[0067] In some implementations, the following processing is included after step S201 and before step S202: Substrate cleaning: The photolithographically etched ITO layer is ultrasonically cleaned sequentially with solvents such as deionized water, acetone, and isopropanol to remove impurities (including photolithography residues and surface contaminants), and then dried with nitrogen gas. Surface treatment: After drying with nitrogen, oxygen plasma treatment is performed. By controlling the treatment time to 1 to 5 minutes, organic contaminants can be completely removed and the wettability of the ITO surface can be significantly improved, which is conducive to the uniform deposition of subsequent organic films. Afterwards, it is placed in a vacuum oven and baked at 110 degrees Celsius for 30 minutes to 1 hour to remove moisture and adsorbed gases.

[0068] The pretreated substrate is then transferred to a high-vacuum coating system, and the chamber vacuum is evacuated to below 1×10⁻⁶. -4 After Pa, each functional layer is deposited sequentially by vapor deposition, as shown in steps S202 to S205.

[0069] In step S202, a first hole transport layer is deposited on the first electrode layer by vapor deposition, wherein the material of the first hole transport layer is TAPC, the thickness is 40nm, and the deposition rate is 0.05nm / s~0.3nm / s.

[0070] Step S203: An active layer is deposited on the first hole transport layer, wherein the active layer is a acceptor material C. 70 The doped layer formed with the donor material TAPC, wherein the acceptor material C 70 The doping concentration is greater than or equal to 60% and less than or equal to 80% by mass, the active layer thickness is 150nm, and the evaporation rate is 0.05nm / s to 0.5nm / s.

[0071] Step S204: Deposit the first electron transport layer on the active layer by vapor deposition.

[0072] In step S205, a second electrode layer is deposited on the first electron transport layer, wherein the intersection of the first and second electrode layers forms an effective photodetector region with an effective area of ​​8 square millimeters. For example, the second electrode layer is a cathode layer with a thickness of 200 nm and a deposition rate of 0.05 nm / s to 2 nm / s.

[0073] Please refer to Figure 5 , Figure 5 Under the same conditions, receptor material C 70 The curves showing the relationship between external quantum efficiency and bias voltage were obtained when the mass ratios were 60%, 70%, and 80%, respectively. Figure 5 The horizontal axis represents the bias voltage, i.e., the voltage applied between the first and second electrode layers, in volts (V). The vertical axis represents the external quantum efficiency (EQE). The same conditions here apply to conditions other than the doping concentration in the active layer, such as the other parameters shown in steps S201 to S205. According to... Figure 5 It can be seen that under the same bias voltage, the acceptor material C 70 When the mass ratio is 80%, the photodetector has a higher external quantum efficiency (EQE), and the maximum external quantum efficiency (EQE) of the photodetector at a bias voltage of -10V can exceed 80%.

[0074] In another specific example, the step of forming a photodetector on one side of the substrate includes: Step S301: A patterned first electrode layer is formed on one side of the substrate.

[0075] Step S302: A first hole transport layer is deposited on the first electrode layer by vapor deposition, wherein the material of the first hole transport layer is TAPC, the thickness is 40nm, and the deposition rate is 0.05nm / s~0.3nm / s.

[0076] Step S303: An active layer is deposited on the first hole transport layer. Exemplarily, the active layer is a receptor material C. 70 The doped layer formed with the donor material TAPC, wherein the acceptor material C 70 The doping concentration is 85%, the active layer thickness is 200 nm, and the evaporation rate is 0.05 nm / s to 2 nm / s.

[0077] Step S304: Deposit the first electron transport layer on the active layer by vapor deposition.

[0078] In step S305, a second electrode layer is deposited on the first electron transport layer, and the intersection of the first and second electrode layers forms an effective photodetector region with an effective area of ​​8 square millimeters. For example, the second electrode layer is a cathode layer with a thickness of 200 nm and a deposition rate of 0.05 nm / s to 2 nm / s.

[0079] The photodetector prepared by the above steps S301 to S305 has the following external quantum efficiency versus wavelength curves under different bias voltages: Figure 6 As shown, Figure 7 This is the curve showing the relationship between external quantum efficiency and wavelength when the bias voltage is -3V. Figure 6 and Figure 7 The horizontal axis represents wavelength, and the vertical axis represents external quantum efficiency (EQE). Figure 6 It is known that the photodetector exhibits a high external quantum efficiency (EQE) for incident light in the wavelength range of 400-600nm. It has a wide-band response, corresponding to full RGB pixel response, and provides a higher signal than traditional R / G single-pixel response detectors, thus improving the signal-to-noise ratio. Furthermore, comparing the EQE under different bias voltages shows that the photodetector can achieve a maximum EQE of 78% at a -3V bias voltage. Figure 7 It can be seen that the photodetector exceeds the C of the acceptor material. 70 After the intrinsic absorption wavelength, the external quantum efficiency (EQE) decreases rapidly, indicating a low exciton density in the charge-transferred state. Furthermore, the dark-state current density versus bias voltage curve of the photodetector prepared through steps S301 to S305 is shown below. Figure 8 As shown, according to Figure 8 It can be seen that, under a bias voltage of -3 V, its dark-state current density Jdark is 1 nA / cm. - ², which means that the photodetector has a low dark-state current density Jdark under high bias voltage.

[0080] Compared with related embodiments, the present disclosure, by introducing a high-doped, high-dielectric-constant acceptor material into the active layer, can not only improve the exciton dissociation efficiency and the external quantum efficiency (EQE), but also reduce the charge-transfer state exciton density at the donor-acceptor interface, thereby reducing the dark-state current density (Jdark) of the photodetector. In other words, the display panel of the present disclosure can achieve a low dark-state current density (Jdark) and a high external quantum efficiency (EQE) under high bias conditions while sharing the hole transport layer with the photodetector and the OLED display device.

[0081] Based on the same inventive concept, a third aspect of this disclosure provides a display device, including the display panel as described above.

[0082] For example, the display device can be any product or component with display function, such as a mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, or navigator. This embodiment does not limit this.

[0083] Preferably, the photodetector in the display device enables fingerprint recognition.

[0084] The display panel can be an OLED display panel. It is understood that other types of display panels can also be used depending on actual needs; for example, the display panel can also be a quantum dot light-emitting diode (QLED) display panel or a micro light-emitting diode (Micro LED) display panel, etc.

[0085] Obviously, the above embodiments of this disclosure are merely examples for clearly illustrating this disclosure, and are not intended to limit the implementation of this disclosure. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all implementation methods here. Any obvious variations or modifications derived from the technical solutions of this disclosure are still within the protection scope of this disclosure.

Claims

1. A display panel, characterized in that, The device includes a substrate and a photodetector and an organic electroluminescent device disposed on one side of the substrate. The photodetector includes an active layer and a first hole transport layer disposed on one side of the active layer. The organic electroluminescent device includes a second hole transport layer. The first hole transport layer and the second hole transport layer are disposed in the same layer. The active layer is a doped layer of acceptor material and donor material. The dielectric constant of the acceptor material is in the range of 4.4 to 5.

1. The ratio of the mass of the acceptor material to the sum of the masses of the acceptor material and the donor material is 60% to 95%.

2. The display panel according to claim 1, characterized in that, The band gap width of the donor material is in the range of 3.1 eV to 3.5 eV.

3. The display panel according to claim 2, characterized in that, The donor material is TAPC or NPB, and the acceptor material is C. 60 Or C 70 .

4. The display panel according to claim 1, characterized in that, The ratio of the mass of the receptor material to the sum of the masses of the receptor material and the donor material is 60-80%.

5. The display panel according to claim 1, characterized in that, The thickness of the active layer is 30~500 nanometers.

6. The display panel according to claim 1, characterized in that, The material of the first hole transport layer is HT002 or TAPC.

7. The display panel according to claim 1, characterized in that, The photodetector further includes a first electrode layer, a first electron transport layer, and a second electrode layer, wherein the first electrode layer, the first hole transport layer, the active layer, the first electron transport layer, and the second electrode layer are stacked sequentially. The organic electroluminescent device further includes a third electrode layer, a light-emitting layer, a second electron transport layer, and a fourth electrode layer, wherein the third electrode layer, the second hole transport layer, the light-emitting layer, the second electron transport layer, and the fourth electrode layer are stacked sequentially. The third electrode layer is disposed in the same layer as the first electrode layer, the second electron transport layer is disposed in the same layer as the first electron transport layer, and the fourth electrode layer is disposed in the same layer as the second electrode layer.

8. The display panel according to claim 7, characterized in that, The area of ​​the overlapping region between the orthographic projection of the first electrode layer on the substrate and the orthographic projection of the second electrode layer on the substrate is 6 to 10 square millimeters.

9. A method for manufacturing a display panel, characterized in that, Includes the following steps: Provide substrates; A photodetector and an organic electroluminescent device are formed on one side of the substrate. The photodetector includes an active layer and a first hole transport layer disposed on one side of the active layer. The organic electroluminescent device includes a second hole transport layer. The first hole transport layer and the second hole transport layer are disposed in the same layer. The active layer is a doped layer of acceptor material and donor material. The dielectric constant of the acceptor material is in the range of 4.4 to 5.1, and the mass ratio of the acceptor material is 60% to 95%.

10. A display device, characterized in that, Includes the display panel as described in any one of claims 1 to 8.

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