Display screen

Abstract

The invention discloses a display screen. The display screen comprises a driving substrate; the plurality of sub-pixels are arranged in the display area of the driving substrate; each sub-pixel comprises a first electrode, a light-emitting layer and a second electrode which are sequentially far away from the driving substrate; the control module is electrically connected with the pixel driving units in the driving substrate; at least partial area of the display area is a light detection area; part of the sub-pixels located in the light detection area are composite function sub-pixels with integrated sensing and displaying functions; the composite function sub-pixel further comprises a light detection layer located between the first electrode and the light-emitting layer or located between the light-emitting layer and the second electrode. And the control module is used for switching the direction of voltage applied to the composite function sub-pixels through the pixel driving unit so as to realize switching between a light emitting working mode and a light detection working mode of the composite function sub-pixels. According to the technical scheme provided by the invention, a detection function can be efficiently integrated, and meanwhile, high-brightness display, high pixel density and a feasible manufacturing process are considered.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronics technology, and more particularly to a display screen. Background Technology

[0002] With the popularization of smart terminal devices, users have increasingly higher requirements for the interactive functions of displays, and displays with integrated fingerprint detection functions have become an important development direction.

[0003] Traditional fingerprint detection solutions mostly rely on optical or capacitive sensors located independently of the OLED (Organic Light-Emitting Diode) display. This separate design has inherent drawbacks: firstly, the additional sensor module increases the overall thickness and hardware cost of the smart terminal; secondly, in optical solutions, the detection signal needs to penetrate multiple layers of media, resulting in low optical coupling efficiency and slow response speed, affecting user experience and recognition accuracy. To overcome these problems, the industry has proposed a technical concept of integrating fingerprint detection functionality within the OLED display.

[0004] In related technologies, when integrating organic photodetectors (OPDs) into OLED displays, a physically separated side-by-side layout is often used. While this approach mitigates the impact on luminous efficiency to some extent, it leads to increased pixel structure complexity. The independent light-emitting and detection areas within each pixel significantly reduce the display's pixel density (Pixels Per Inch, PPI), affecting display clarity, and also greatly increases the complexity of manufacturing processes, posing challenges to yield control. Therefore, there is an urgent need in this field for an innovative display architecture that can efficiently integrate detection functions while simultaneously achieving high brightness, high pixel density, and feasible manufacturing processes. Summary of the Invention

[0005] This invention provides a display screen that can efficiently integrate detection functions while also achieving high brightness, high pixel density, and feasible manufacturing processes.

[0006] This invention provides a display screen, comprising:

[0007] A driving substrate includes a substrate and a plurality of pixel driving units located on one side of the substrate;

[0008] Multiple sub-pixels are arranged in the display area of ​​the driving substrate; each sub-pixel includes a first electrode, a light-emitting layer, and a second electrode that are sequentially located away from the driving substrate; the first electrode of each sub-pixel is electrically connected to a pixel driving unit.

[0009] The control module is electrically connected to the pixel driving unit in the driving substrate;

[0010] Wherein, at least a portion of the display area is a light detection area; a portion of the sub-pixels located in the light detection area are composite functional sub-pixels integrating sensing and display functions; the composite functional sub-pixel further includes a light detection layer located between the first electrode and the light-emitting layer or between the light-emitting layer and the second electrode; the control module is used to switch the voltage direction applied to the composite functional sub-pixel through the pixel driving unit to realize the switching between the light emission working mode and the light detection working mode of the composite functional sub-pixel.

[0011] Optionally, the photodetector layer includes:

[0012] A first functional layer and a second functional layer are stacked together; the first functional layer is made of a P-type organic semiconductor material, and the second functional layer is made of an N-type organic semiconductor material.

[0013] The first functional layer and the second functional layer are used to form a PN junction structure; when the composite functional sub-pixel is in the light-emitting working mode, the PN junction structure is used to transport charge carriers; when the composite functional sub-pixel is in the light-detecting working mode, the PN junction structure is used to detect fingerprint reflected light.

[0014] Optionally, the first electrode is the anode and the second electrode is the cathode;

[0015] When the photodetector layer is located between the first electrode and the light-emitting layer, the first functional layer is closer to the first electrode than the second functional layer;

[0016] When the photodetector layer is located between the second electrode and the light-emitting layer, the second functional layer is closer to the second electrode than the first functional layer.

[0017] Optionally, the photodetector layer comprises a blend of P-type organic semiconductor material and N-type organic semiconductor material, wherein the P-type organic semiconductor material and N-type organic semiconductor material form a bulk heterojunction structure in the photodetector layer.

[0018] Optionally, the P-type organic semiconductor material includes one or more of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate), poly3-hexylthiophene, and copper phthalocyanine;

[0019] The N-type organic semiconductor material includes fullerene C. 60 One or more of perylenetetracarboxylic dianhydride and N,N'-dioctyl-3,4,9,10-perylenediimide.

[0020] Optionally, when the photodetector layer is located between the first electrode and the light-emitting layer, the electron mobility of the bulk material of the light-emitting layer in the composite functional sub-pixel is greater than the hole mobility.

[0021] When the photodetector layer is located between the second electrode and the light-emitting layer, the hole mobility of the bulk material of the light-emitting layer in the composite functional sub-pixel is greater than the electron mobility.

[0022] Optionally, the absolute value of the difference between the absorption wavelength of the composite functional sub-pixel and the emission wavelength of the sub-pixel is less than or equal to 30 nm.

[0023] Optionally, the plurality of sub-pixels includes red sub-pixels, green sub-pixels, and blue sub-pixels; the composite functional sub-pixel is one or more of the red sub-pixels, green sub-pixels, and blue sub-pixels;

[0024] The absolute value of the difference between the absorption wavelength of the composite functional sub-pixel and the emission wavelength of the red sub-pixel is less than or equal to 30 nm; or the absolute value of the difference between the absorption wavelength of the composite functional sub-pixel and the emission wavelength of the green sub-pixel is less than or equal to 30 nm; or the absolute value of the difference between the absorption wavelength of the composite functional sub-pixel and the emission wavelength of the blue sub-pixel is less than or equal to 30 nm.

[0025] Optionally, the plurality of sub-pixels includes a plurality of composite function sub-pixels and a plurality of single function sub-pixels; the single function sub-pixels are configured to perform only the light-emitting function; at least the single function sub-pixels further include:

[0026] At least one of a hole injection layer, a hole transport layer, and an electron blocking layer located between the first electrode and the light-emitting layer; and / or at least one of an electron injection layer, an electron transport layer, and a hole blocking layer located between the second electrode and the light-emitting layer;

[0027] Wherein, the absolute value of the difference between the total film thickness between the first electrode and the light-emitting layer in the single-function sub-pixel and the total film thickness between the first electrode and the light-emitting layer in the composite-function sub-pixel is less than a preset difference.

[0028] Optionally, the plurality of sub-pixels constitute a plurality of pixel units arranged in an array; each pixel unit includes a green emitting sub-pixel, a red emitting sub-pixel, and a blue emitting sub-pixel;

[0029] In the light detection area, the number of composite functional sub-pixels in the pixel unit containing the composite functional sub-pixel is less than or equal to 2; and / or, each n×m pixel unit array has one pixel unit containing the composite functional sub-pixel, where n is the number of rows in the pixel unit array, m is the number of columns in the pixel unit array, n is an integer greater than or equal to 1, and m is an integer greater than or equal to 1.

[0030] Optionally, the display screen further includes:

[0031] A power supply module is configured to provide at least a first power supply voltage and a second power supply voltage to the sub-pixel array; wherein...

[0032] The pixel driving unit connected to the single-function sub-pixel is electrically connected to a first power supply voltage transmission line and is configured to provide a positive bias voltage to the single-function sub-pixel using the first power supply voltage.

[0033] The pixel driving unit connected to the composite functional sub-pixel integrates a voltage switching module and is electrically connected to a second power supply voltage transmission line and a first power supply voltage transmission line. The voltage switching module is configured to provide a reverse bias voltage to the composite functional sub-pixel using the second power supply voltage and to provide a forward bias voltage to the composite functional sub-pixel using the first power supply voltage.

[0034] The control module is configured to output synchronization control signals to the plurality of independent pixel driving units so that the composite functional sub-pixels and the single functional sub-pixels can work together.

[0035] The technical solution provided by this invention embeds a photodetector layer inside an OLED to form a composite functional sub-pixel. This sub-pixel emits light and displays under a forward bias, and performs photodetection under a reverse bias. This allows the same structure to achieve both display and detection functions under different biases, significantly improving the integration and pixel density of the display screen. Furthermore, setting some sub-pixels in the photodetector area as composite functional sub-pixels integrating sensing and display functions improves the luminous efficiency of the display screen compared to setting all sub-pixels as composite functional sub-pixels. In addition, compared to the parallel arrangement of OLED and OPD in related technologies, this invention stacks the organic material layers in the OLED and OPD sequentially in the vertical direction, allowing them to share electrodes. Moreover, some film layers can be deposited using the same mask, thereby reducing the process complexity and manufacturing cost of the display screen. This achieves the effect of highly efficient integration of detection functions while also considering high brightness display, high pixel density, and feasible manufacturing processes.

[0036] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of a display screen performing fingerprint recognition according to an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of a display screen performing palm detection according to an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of the structure of a composite functional sub-pixel provided in an embodiment of the present invention;

[0041] Figure 4 yes Figure 3 The diagram shows the operation of the structure under a forward bias voltage.

[0042] Figure 5 yes Figure 3 The diagram shows the operation of the structure under reverse bias voltage.

[0043] Figure 6 This is a schematic diagram of another composite functional sub-pixel provided in an embodiment of the present invention;

[0044] Figure 7 yes Figure 6 The diagram shows the operation of the structure under a forward bias voltage.

[0045] Figure 8 yes Figure 6 The diagram shows the operation of the structure under reverse bias voltage.

[0046] Figure 9 This is a schematic diagram of another composite functional sub-pixel provided in an embodiment of the present invention;

[0047] Figure 10 This is a schematic diagram of another composite functional sub-pixel provided in an embodiment of the present invention;

[0048] Figure 11 This is a partial structural diagram of a display screen provided in an embodiment of the present invention;

[0049] Figure 12 This is a schematic diagram of the structure of a single-function sub-pixel provided in an embodiment of the present invention;

[0050] Figure 13 This is a schematic diagram of the arrangement of sub-pixels located in the light detection area of ​​a display screen, provided by an embodiment of the present invention;

[0051] Figure 14 This is a schematic diagram of another arrangement of sub-pixels located in the light detection area of ​​the display screen provided by an embodiment of the present invention. Detailed Implementation

[0052] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0053] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0054] This invention provides a display screen, characterized in that it includes:

[0055] A driving substrate, including a substrate and a plurality of pixel driving units located on one side of the substrate;

[0056] Multiple sub-pixels are arranged in the display area of ​​the driving substrate; each sub-pixel includes a first electrode, a light-emitting layer and a second electrode that are sequentially moved away from the driving substrate; the first electrode of each sub-pixel is electrically connected to a pixel driving unit.

[0057] The control module is electrically connected to the pixel driving unit in the driving substrate;

[0058] At least a portion of the display area is a light detection area; that is, the entire display area can be set as a light detection area to achieve full-screen light detection; or a portion of the display area can be set as a light detection area to achieve local light detection. The number of light detection areas can be one or more. A portion of the sub-pixels located in the light detection area is a composite functional sub-pixel integrating sensing and display functions; the composite functional sub-pixel also includes a light detection layer located between the first electrode and the light-emitting layer or between the light-emitting layer and the second electrode; the control module is used to switch the direction of the voltage applied to the composite functional sub-pixel through the pixel driving unit to switch the composite functional sub-pixel's light-emitting operating mode and light detection operating mode. By switching the composite functional sub-pixel to the light detection operating mode, the display screen 100 can achieve, for example... Figure 1 The fingerprint recognition function shown or as Figure 2 The palm detection function shown.

[0059] The technical solution provided by this invention embeds a photodetector layer inside the OLED to form a composite functional sub-pixel. This sub-pixel emits light and displays under a forward bias, and performs photodetection under a reverse bias. This allows the same structure to achieve display and detection functions under different biases, significantly improving the integration and pixel density of the display screen. Furthermore, by designating some sub-pixels in the photodetector area as composite functional sub-pixels integrating sensing and display functions, the luminous efficiency of the display screen can be improved compared to setting all sub-pixels as composite functional sub-pixels. In addition, in related technologies, OLEDs and OPDs are arranged side-by-side, requiring the precise deposition of different organic materials in two adjacent tiny pixel regions. This places extremely high demands on the alignment accuracy of the f-mmm unit (FMM), increasing the process difficulty and product defect rate. Moreover, the film deposition, patterning, and electrode extraction processes of OLEDs and OPDs need to be performed alternately or repeatedly, making the entire process lengthy and affecting production efficiency and yield. In this invention, the organic material layers in the OLED and OPD are stacked sequentially in the vertical direction, allowing for electrode sharing. Furthermore, some film layers can be deposited using the same mask, thereby reducing the process complexity and manufacturing cost of the display screen. This achieves efficient integration of light detection functions while simultaneously ensuring high brightness, high pixel density, and simplified manufacturing processes. The display screen provided in this invention can be widely used in smart terminals such as smartphones and tablets, and has broad application prospects.

[0060] The above are the core inventive points of this invention. The structure of the composite functional sub-pixel will be described in detail below with reference to the accompanying drawings.

[0061] In some embodiments of the present invention, reference is made to Figure 3 and Figure 6The photodetector layer 20 includes a first functional layer 21 and a second functional layer 22 stacked together; the first functional layer 21 is made of a P-type organic semiconductor material, that is, the first functional layer 21 is a P-type organic semiconductor layer; the second functional layer 22 is made of an N-type organic semiconductor material, that is, the second functional layer 22 is an N-type organic semiconductor layer.

[0062] The first functional layer 21 and the second functional layer 22 are used to form a PN junction structure. When the composite functional sub-pixel is in the light-emitting working mode, the PN junction structure is used to transport charge carriers. When the composite functional sub-pixel is in the light-detecting working mode, the PN junction structure is used to detect light, such as fingerprint reflection light or palm reflection light.

[0063] For details, see Figure 3 With the photodetector layer 20 located between the first electrode 11 and the light-emitting layer 30, the first functional layer 21 is closer to the first electrode 11 than the second functional layer 22. (Reference) Figure 6 When the photodetector layer 20 is located between the second electrode 12 and the light-emitting layer 30, the second functional layer 22 is closer to the second electrode 12 than the first functional layer 21. Figure 3 and Figure 6 In the structure shown, the first electrode 11 is the anode Ad, and the second electrode 12 is the cathode Cd. That is, if the photodetector layer 20 is located between the anode Ad and the light-emitting layer 30, the P-type organic semiconductor layer is located on the side of the N-type organic semiconductor layer closer to the anode Ad, and the N-type organic semiconductor layer is located on the side of the P-type organic semiconductor layer closer to the light-emitting layer 30. If the photodetector layer 20 is located between the cathode Cd and the light-emitting layer 30, the P-type organic semiconductor layer is located on the side of the N-type organic semiconductor layer closer to the light-emitting layer 30, and the N-type organic semiconductor layer is located on the side of the P-type organic semiconductor layer closer to the cathode Cd. In other embodiments of the present invention, the first electrode 11 can be the cathode Cd, and the second electrode 12 can be the anode Ad; in this case, if the photodetector layer 20 is located between the first electrode 11 and the light-emitting layer 30, the second functional layer 22 is closer to the first electrode 11 than the first functional layer 21; if the photodetector layer 20 is located between the second electrode 12 and the light-emitting layer 30, the first functional layer 21 is closer to the second electrode 12 than the second functional layer 22.

[0064] When using composite functional subpixels as OLEDs, refer to Figure 4 and Figure 7The composite functional sub-pixel is input with a positive bias voltage, meaning the anode Ad is connected to the positive terminal of the power supply, and the cathode Cd is connected to the negative terminal. The electric field direction is from the anode Ad to the cathode Cd. At this time, the electric field drives the charge carriers as follows: holes (positive charges) migrate towards the cathode Cd along the electric field direction, while electrons (negative charges) migrate towards the anode Ad against the electric field direction. They eventually meet and recombine in the emitting layer 30, forming excitons (electron-hole pairs). The excitons transition from the excited state back to the ground state, releasing energy that is radiated as photons, thus emitting light. Therefore, under the positive bias voltage, the first functional layer 21 acts as a hole transport functional layer, transferring the holes injected by the anode Ad to the emitting layer 30.

[0065] The first functional layer 21 comprises at least one hole transport material, which is an electron-rich organic semiconductor material. The deviation between the highest occupied molecular orbital energy level of the hole transport material and the work function of the anode Ad can be set to be less than a preset deviation, making the work function of the anode Ad more closely matched with the highest occupied molecular orbital energy level of the first functional layer 21, thus facilitating hole injection from the anode Ad into the first functional layer 21. The second functional layer 22 comprises at least one electron transport material, which is an electron-deficient organic semiconductor material.

[0066] When using composite function subpixels as OPDs, refer to Figure 5 and 8 The composite functional sub-pixel is input with a reverse bias voltage, meaning the anode Ad is connected to the negative terminal of the power supply, and the cathode Cd is connected to the positive terminal. Both the first functional layer 21 and the second functional layer 22 serve as light absorption layers. Under illumination, the first functional layer 21 and the second functional layer 22 absorb light of their respective target wavelengths, generating excitons. The first functional layer 21 and the second functional layer 22 form a PN heterojunction. Through the built-in electric field of the PN heterojunction, the excitons are split into free holes and electrons. Ultimately, the holes are collected by the anode Ad, and the electrons are collected by the cathode Cd, forming a photocurrent (the direction of the photocurrent is consistent with the direction of the reverse bias voltage).

[0067] Therefore, the P-type organic semiconductor material of the first functional layer 21 has both hole transport and light absorption properties; the N-type organic semiconductor material of the second functional layer 22 has both electron transport and light absorption properties. For example, the material of the first functional layer 21 includes one or more of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate), poly3-hexylthiophene, and copper phthalocyanine. The material of the second functional layer 22 includes fullerene C... 60 One or more of the following: perylene tetracarboxylic dianhydride (PTCDA) and N,N'-dioctyl-3,4,9,10-perylene diimide.

[0068] In other embodiments of the invention, reference is made to... Figure 9 and Figure 10 The photodetector layer 20 comprises a blend of P-type and N-type organic semiconductor materials, which form a bulk heterojunction structure within the photodetector layer 20. Figure 9 An exemplary illustration shows that the photodetector layer 20 is located between the first electrode 11 and the light-emitting layer 30. Figure 10 An exemplary embodiment shows that the light detection layer 20 is located between the second electrode 12 and the light-emitting layer 30; the first electrode 11 is the anode Ad, and the second electrode 12 is the cathode Cd.

[0069] Specifically, a blended layer formed by mixing P-type organic semiconductor materials (donors) and N-type organic semiconductor materials (acceptors) serves as the photodetector layer 20. Within this blended layer, the P-type and N-type organic semiconductor materials form a nanoscale, interpenetrating, and continuous network, thereby increasing the area of ​​the P / N interface. In organic semiconductors, light absorption does not produce free electrons and holes, but rather bound electron-hole pairs called "excitons." Excitons have a very short lifetime, moving only within a very short distance (typically about 10-20 nanometers). If a P / N interface cannot be found within this distance, it will disappear (recombine) through luminescence or heat, resulting in energy loss. In the blended bulk heterojunction, the P-type and N-type materials interweave at the nanoscale, ensuring that excitons generated at any location can find a P / N interface within an extremely short diffusion distance, thus efficiently separating into free electrons and holes.

[0070] The technical solution provided in this invention involves preparing a photodetector layer 20 with microscopically phase-separated, interpenetrating networks and macroscopically uniform structure by solution blending of P-type (donor) and N-type (acceptor) organic semiconductor materials. This configuration significantly improves the efficiency of exciton separation and charge collection in the composite functional sub-pixel by creating a large three-dimensional internal interface. The P-type organic semiconductor material may include one or more of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate), poly3-hexylthiophene, and copper phthalocyanine; the N-type organic semiconductor material may include fullerene C... 60 One or more of perylene tetracarboxylic dianhydride (PTCDA) and N,N'-dioctyl-3,4,9,10-perylene diimide.

[0071] In summary, the specific implementation methods of the display screen's sensing function include:

[0072] The control module applies a positive bias voltage to all sub-pixels through the driving circuit layer. In the PN junction structure of the composite functional sub-pixel, the PN junction acts as an injection layer and works synchronously with the conventional OLED sub-pixels to achieve sub-pixel light emission. Image display is achieved through RGB three primary color mixing.

[0073] The control module applies a reverse bias voltage to the composite functional sub-pixel through the driving circuit layer, causing its PN junction to form a depletion region as an OPD detection layer. At the same time, a forward bias voltage is applied to the conventional OLED sub-pixel to make it emit light. The light emitted by the conventional OLED sub-pixel is reflected by the fingerprint surface and absorbed by the composite functional sub-pixel. The resulting photocurrent is transmitted to the control module through the driving circuit layer and generated into a fingerprint image after signal processing.

[0074] Based on the above embodiments, optionally, the forward bias voltage ranges from 3V to 15V, and the reverse bias voltage ranges from 0.1V to 5V.

[0075] Based on the above embodiments, optionally, refer to... Figure 3 and Figure 9 When the photodetector layer 20 is located between the first electrode 11 and the light-emitting layer 30, the electron mobility of the bulk material of the light-emitting layer 30 in the composite functional sub-pixel is greater than the hole mobility; Reference Figure 6 and Figure 10 When the photodetector layer 20 is located between the second electrode 12 and the light-emitting layer 30, the hole mobility of the main material of the light-emitting layer 30 in the composite functional sub-pixel is greater than the electron mobility; wherein, the first electrode 11 is the anode Ad and the second electrode 12 is the cathode Cd.

[0076] Specifically, the light-emitting layer 30 is the core layer of the device, where photons are generated. The light-emitting layer 30 can be composed of a host material and a guest material, also known as a dopant. Electrons and holes meet and recombine in the light-emitting layer 30 to form excitons, which emit light when de-excited. The host material possesses excellent carrier transport capabilities and a high triplet energy level (to prevent energy from being transferred back to the guest material). By selecting dopant materials with different emission wavelengths, the device can precisely control the emission of red, green, blue, or other colors of light. When the photodetector layer 20 is located between the first electrode 11 and the light-emitting layer 30, the electron mobility of the main material of the light-emitting layer 30 in the composite functional sub-pixel is greater than the hole mobility. This allows electrons injected from the cathode Cd to continue to propagate in the direction of the photodetector layer 20 after entering the light-emitting layer 30, thereby shortening the distance between electrons and holes and the time it takes for electrons and holes to meet. This is beneficial for electron-hole recombination and light emission, thus improving luminous efficiency. When the photodetector layer 20 is located between the second electrode 12 and the light-emitting layer 30, the hole mobility of the main material of the light-emitting layer 30 in the composite functional sub-pixel is greater than the electron mobility. This allows holes injected from the anode Ad to continue to propagate in the direction of the photodetector layer 20 after entering the light-emitting layer 30, thereby shortening the distance between electrons and holes and the time it takes for electrons and holes to meet. This is beneficial for electron-hole recombination and light emission, thus improving luminous efficiency.

[0077] Based on the above embodiments, refer to Figures 3-10 Optionally, the light-emitting layer 30 can also be an undoped light-emitting layer 30, that is, the light-emitting layer 30 is composed of a single light-emitting material. Such materials usually have good charge transport capability and luminous efficiency. Therefore, when the photodetector layer 20 is located between the first electrode 11 and the light-emitting layer 30, the electron mobility of the material of the light-emitting layer 30 in the composite functional sub-pixel is greater than the hole mobility; when the photodetector layer 20 is located between the second electrode 12 and the light-emitting layer 30, the hole mobility of the material of the light-emitting layer 30 in the composite functional sub-pixel is greater than the electron mobility. The beneficial effects will not be elaborated here.

[0078] Based on the above embodiments, refer to Figures 3-10 Optionally, the absolute value of the difference between the absorption wavelength and the emission wavelength of the composite functional sub-pixel is less than or equal to 30 nm.

[0079] Specifically, during fingerprint recognition or palm detection, the fingerprint or palm reflected light received by the composite functional sub-pixel can be emitted from a single functional sub-pixel (conventional OLED sub-pixel) and / or a composite functional sub-pixel in its light-emitting mode. By setting the absolute value of the difference between the absorption wavelength and the emission wavelength of the composite functional sub-pixel to be less than or equal to 30nm, the light absorption efficiency of the composite functional sub-pixel in its detection mode can be improved.

[0080] Further reference Figure 11 Multiple sub-pixels P include a red sub-pixel R, a green sub-pixel G, and a blue sub-pixel B; the red sub-pixel R emits red light, the green sub-pixel G emits green light, and the blue sub-pixel B emits blue light. Different colors can be displayed by adjusting the brightness of the red sub-pixel R, the green sub-pixel G, and the blue sub-pixel B. A composite functional sub-pixel Pf is one or more of the red, green, and blue sub-pixels. For example, refer to... Figure 11 In the structure shown, the red sub-pixel R in the display screen is set as a composite function sub-pixel Pf.

[0081] Optionally, the absolute value of the difference between the absorption wavelength of the composite functional sub-pixel Pf and the emission wavelength of the red sub-pixel R is less than or equal to 30 nm, or the absolute value of the difference between the absorption wavelength of the composite functional sub-pixel Pf and the emission wavelength of the green sub-pixel G is less than or equal to 30 nm, or the absolute value of the difference between the absorption wavelength of the composite functional sub-pixel Pf and the emission wavelength of the blue sub-pixel B is less than or equal to 30 nm.

[0082] In other embodiments of the present invention, the absorption wavelength ranges of different composite functional sub-pixels Pf can be different. It can be set that the absolute value of the difference between the absorption wavelength of some composite functional sub-pixels Pf and the emission wavelength of the red sub-pixel R is less than or equal to 30 nm, the absolute value of the difference between the absorption wavelength of some composite functional sub-pixels Pf and the emission wavelength of the green sub-pixel G is less than or equal to 30 nm, and the absolute value of the difference between the absorption wavelength of some composite functional sub-pixels Pf and the emission wavelength of the blue sub-pixel B is less than or equal to 30 nm.

[0083] Based on the above embodiments, optionally, the display screen includes multiple composite functional sub-pixels Pf and multiple single functional sub-pixels Pd; the single functional sub-pixels Pd are configured to perform only the light-emitting function. The single functional sub-pixel Pd includes a first electrode 11, a light-emitting layer 30, and a second electrode 12, which are sequentially located away from the driving substrate, wherein the first electrode 11 is the anode Ad and the second electrode 12 is the cathode Cd.

[0084] Furthermore, the single-function sub-pixel Pd also includes at least one of a hole injection layer 31, a hole transport layer 32, and an electron blocking layer 33 located between the first electrode 11 and the light-emitting layer 30; and / or at least one of an electron injection layer 34, an electron transport layer 35, and a hole blocking layer 36 located between the second electrode 12 and the light-emitting layer 30.

[0085] For example, refer to Figure 12The single-function sub-pixel Pd further includes: a hole injection layer 31, a hole transport layer 32, and an electron blocking layer 33 located between the first electrode 11 and the light-emitting layer 30; and at least one of an electron injection layer 34, an electron transport layer 35, and a hole blocking layer 36 located between the second electrode 12 and the light-emitting layer 30. The hole injection layer 31, hole transport layer 32, electron blocking layer 33, electron injection layer 34, electron transport layer 35, and hole blocking layer 36 are all conventional functional layers in conventional OLED sub-pixels, and will not be described in detail here.

[0086] Furthermore, the composite functional sub-pixel Pf also includes at least one of a hole injection layer 31, a hole transport layer 32, and an electron blocking layer 33 located between the first electrode 11 and the light-emitting layer 30; and / or at least one of an electron injection layer 34, an electron transport layer 35, and a hole blocking layer 36 located between the second electrode 12 and the light-emitting layer 30. It should be noted that the conventional functional layer located on the same side of the light-emitting layer 30 as the photodetector layer 20 is closer to the light-emitting layer 30 than the photodetector layer 20.

[0087] Based on the above embodiments, optionally, the absolute value of the difference between the total film thickness between the first electrode 11 and the light-emitting layer 30 in the single-function sub-pixel Pd and the total film thickness between the first electrode 11 and the light-emitting layer 30 in the composite-function sub-pixel Pf is less than a preset difference.

[0088] Specifically, by setting the absolute value of the difference between the total film thickness between the first electrode 11 and the light-emitting layer 30 in the single-function sub-pixel Pd and the total film thickness between the first electrode 11 and the light-emitting layer 30 in the composite-function sub-pixel Pf to be less than a preset difference, the height difference between the light-emitting layer 30 in the single-function sub-pixel Pd and the light-emitting layer 30 in the composite-function sub-pixel Pf relative to the driving substrate can be less than the preset difference. This helps reduce optical crosstalk between the composite-function sub-pixel Pf and the single-function sub-pixel Pd, and avoids interference from light emitted from the sidewalls of the surrounding single-function sub-pixel Pd when the composite-function sub-pixel Pf performs fingerprint recognition or palm detection. Furthermore, it also improves the flatness of the subsequently fabricated film layers.

[0089] Furthermore, the absolute value of the difference between the total film thickness between the second electrode 12 and the first electrode 11 in the single-function sub-pixel Pd and the total film thickness between the first electrode 11 and the second electrode 12 in the composite-function sub-pixel Pf is less than a preset difference. This allows the height difference between the second electrode 12 in the single-function sub-pixel Pd and the second electrode 12 in the composite-function sub-pixel Pf relative to the driving substrate to be less than the preset difference. This is beneficial for the fabrication of the shared cathode layer Cd1, allowing different sub-pixels to share the same cathode layer, further reducing the fabrication complexity of the display screen.

[0090] For example, in one specific embodiment of the present invention, using Figure 11 Taking the displayed screen as an example, the manufacturing method of the display screen includes:

[0091] S1. Provide a substrate containing a TFT array and an anode Ad, and clean it by ultrasonic cleaning with deionized water and isopropanol for 15 minutes respectively to remove surface oil and impurities, and then treat it in an oven at 100°C for 2 hours.

[0092] S2, forming the first functional layer 21, the second functional layer 22, the hole transport layer 32, and the red light emission layer 30r in the composite functional sub-pixel Pf (taking the red sub-pixel R as an example). Specific steps can be as follows:

[0093] The red vapor deposition area is defined using a precision photomask (FMM);

[0094] A first functional layer 21 (p-type organic semiconductor layer) is formed; copper phthalocyanine (CuPc) is deposited using vacuum evaporation at a rate of 0.1 nm / s to 0.3 nm / s and a vacuum level better than 5 × 10⁻⁶. -4 Pa, with a thickness of approximately 40 nm. CuPc exhibits excellent hole transport performance, with a HOMO energy level of approximately -5.2 eV, which matches well with the energy level of hole injection layer 31;

[0095] Forming a second functional layer 22 (N-type organic semiconductor layer); depositing fullerene (C) using vacuum evaporation. 60 The evaporation rate ranges from 0.2 nm / s to 0.4 nm / s, with a thickness of approximately 30 nm. C 60 It is an excellent n-type organic semiconductor material with a LUMO energy level of approximately -4.0 eV and high electron mobility. It matches the LUMO energy level of the light-emitting layer 30, which is beneficial for electron transport. At the same time, it can form an effective depletion region under reverse voltage, serving as the core of the OPD detector layer.

[0096] A hole transport layer 32 is formed; NPB is deposited by vacuum evaporation at a rate of 0.2 nm / s to 0.3 nm / s, with a thickness of approximately 30 nm. The HOMO level of the NPB is -5.4 eV, exhibiting excellent hole transport performance.

[0097] Forming a red luminescent layer 30r: A red luminescent material, such as bis(1-phenylisoquinoline)(acetylacetone)iridium (Ir(piq)2(acac)) doped host material CBP, is deposited by vacuum evaporation with a doping concentration of 6%, a thickness of about 50 nm, and an emission peak of about 620 nm.

[0098] S3, forming the hole injection layer 31, hole transport layer 32, and green light emission layer 30g in the green sub-pixel G. Specific steps may include:

[0099] A precision metal mask (FMM) is used to define the green vapor deposition area;

[0100] Hole injection layer 31 is formed; 1,4,5,8,9,12-hexaazabenzophenanthrenehexanitrile (HAT-CN) is vacuum-deposited using a vacuum evaporation method with a deposition rate ranging from 0.1 nm / s to 0.2 nm / s and a thickness ranging from 5 nm to 10 nm. The HOMO level of HAT-CN is approximately -5.8 eV, which has a high-efficiency hole injection capability and can reduce the potential barrier between the anode Ad and the hole transport layer 32.

[0101] A hole transport layer 32 is formed; NPB is deposited by vacuum evaporation with a deposition rate ranging from 0.2 nm / s to 0.3 nm / s and a thickness of approximately 30 nm. The HOMO level of NPB is -5.4 eV, exhibiting excellent hole transport performance.

[0102] A 30g green luminescent layer was formed by co-evaporation of tris(2-phenylpyridine)iridium (Ir(ppy)3) as the green luminescent material and 4,4'-bis(9-carbazole)biphenyl (CBP) as the host material. The doping concentration of Ir(ppy)3 was 8%, the total evaporation rate was 0.2-0.4 nm / s, and the thickness was approximately 50 nm. The emission peak of Ir(ppy)3 was approximately 520 nm, the HOMO level of CBP was approximately -5.5 eV, and the LUMO level was approximately -2.3 eV, which can effectively transport holes and confine electrons.

[0103] S4. Form the hole injection layer 31, hole transport layer 32, and blue light emitting layer 30b in the blue sub-pixel B. Specific steps may include:

[0104] The blue vapor deposition area is defined using a precision photomask (FMM);

[0105] Hole injection layer 31 is formed; 1,4,5,8,9,12-hexaazabenzophenanthrenehexanitrile (HAT-CN) is vacuum-deposited using a vacuum evaporation method with a deposition rate ranging from 0.1 nm / s to 0.2 nm / s and a thickness ranging from 5 nm to 10 nm. The HOMO energy level of HAT-CN is approximately -5.8 eV, which has a high-efficiency hole injection capability and can reduce the potential barrier between the anode Ad and the hole transport layer 32.

[0106] A hole transport layer 32 is formed; NPB is deposited by vacuum evaporation at a rate of 0.2-0.3 nm / s with a thickness of approximately 30 nm. The HOMO level of NPB is -5.4 eV, exhibiting excellent hole transport performance.

[0107] Blue light emitting layer 30b is formed by depositing the blue light emitting material guest material Firpi and the host material CBP doped with it using a co-evaporation method. The doping concentration is 10%, the thickness is about 50nm, and the emission peak is about 470nm.

[0108] S5. Form the electron transport layer 35 (open mask) for all sub-pixels. Specific steps may include:

[0109] Bis(2-phenylpyridine)beryllium (Bepp2) and lithium 8-hydroxyquinoline (Liq) were co-vacuum deposited in a blend ratio of 1:0.5. The total deposition rate ranged from 0.2 to 0.3 nm / s (Bepp2 rate was 0.13 to 0.2 nm / s, and Liq rate was 0.07 nm / s to 0.1 nm / s), with a thickness of approximately 30 nm to 50 nm. The LUMO level of Bepp2 is approximately -2.7 eV. Liq doping can reduce the electron injection barrier and improve electron transport efficiency.

[0110] S6. Form a common cathode layer Cd1. Specific steps may include:

[0111] Silver (Ag) and magnesium (Mg) are co-deposited in a 9:1 ratio, with a total evaporation rate ranging from 0.1 nm / s to 0.2 nm / s (Ag rate from 0.09 nm / s to 0.18 nm / s, and Mg rate from 0.01 nm / s to 0.02 nm / s), resulting in a thickness of approximately 20 nm. The work function of Ag is approximately -4.3 eV, and that of Mg is approximately -3.7 eV. Co-evaporation can reduce the work function of the cathode Cd while maintaining good conductivity and optical transmittance, making it suitable for semi-transparent light emission requirements.

[0112] Furthermore, after forming the common cathode layer Cd1, the process also includes:

[0113] S7. Form the light extraction layer (using an open mask). Specific steps include:

[0114] Vacuum evaporation of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) at a rate ranging from 0.2 to 0.3 nm / s and a thickness of approximately 50 nm, with a refractive index of approximately 1.75, can effectively reduce waveguide mode light loss within the device, improve light extraction efficiency, and enhance the device's light extraction performance.

[0115] S8. Form a thin-film encapsulation layer. Specific steps may include:

[0116] Atomic layer deposition (ALD) technology was used to deposit an Al2O3 layer with a thickness of about 100 nm on the cathode Cd layer as an inorganic encapsulation layer. The deposition temperature range was 80-100℃ to ensure deposition quality and device stability. Then, an organic encapsulation material (such as polyimide) with a thickness of about 1 μm was coated by spin coating and cured at 120℃ for 1 hour.

[0117] Repeat the deposition process of the inorganic and organic encapsulation layers to form a three-layer encapsulation structure of "inorganic-organic-inorganic", with a total thickness ranging from approximately 5 to 10 μm.

[0118] Based on the above embodiments, optionally, refer to... Figure 13 and Figure 14 Multiple sub-pixels constitute multiple pixel units P0 arranged in an array; each pixel unit P0 includes a green luminous sub-pixel G, a red luminous sub-pixel R, and a blue luminous sub-pixel B;

[0119] In the photodetector region, the number of composite functional sub-pixels Pf in pixel unit P0 containing composite functional sub-pixels Pf is less than or equal to 2; and / or, every n×m pixel unit array has one pixel unit P0 containing composite functional sub-pixels Pf, where n is the number of rows in the pixel unit array, m is the number of columns in the pixel unit array, n is an integer greater than or equal to 1, and m is an integer greater than or equal to 1. Figure 13 and Figure 14 All examples exemplify that the number of composite functional sub-pixels Pf in pixel unit P0 containing composite functional sub-pixels Pf is 1. Figure 13 An example is shown where each pixel unit P0 includes a composite function sub-pixel Pf. Figure 14 An exemplary 2×2 pixel unit array has a pixel unit P0 containing a composite function subpixel Pf.

[0120] Based on the above embodiments, optionally, the display screen further includes:

[0121] A power supply module is configured to provide at least a first power supply voltage and a second power supply voltage to the sub-pixel array; wherein...

[0122] The pixel driving unit 200, which is connected to the single-function sub-pixel Pd, is electrically connected to the first power supply voltage transmission line and is configured to provide a positive bias voltage to the single-function sub-pixel Pd using the first power supply voltage.

[0123] The pixel driving unit 200 connected to the composite functional sub-pixel Pf integrates a voltage switching module and is electrically connected to the second power supply voltage transmission line and the first power supply voltage transmission line. The voltage switching module is configured to provide a reverse bias voltage to the composite functional sub-pixel Pf using the second power supply voltage and to provide a forward bias voltage to the composite functional sub-pixel Pf using the first power supply voltage.

[0124] The control module is configured to output synchronous control signals to multiple independent pixel driving units 200 so that the composite function sub-pixel Pf and the single function sub-pixel Pd can work together.

[0125] For details, please refer to Figure 11 The driving substrate refers to a film layer structure that provides driving signals to the display screen and serves as a buffer, protector, or support. It includes a substrate 01 and a driving circuit layer 02 disposed on the substrate 01. The driving circuit layer 02 includes multiple pixel driving units 200, each pixel driving unit 200 being electrically connected to a sub-pixel P to drive the sub-pixel P to emit light. The pixel driving unit 200 connected to the composite functional sub-pixel Pf can apply a forward bias voltage to the composite functional sub-pixel Pf or a reverse bias voltage to the composite functional sub-pixel Pf. The control module can be a driving chip used to switch the voltage direction of the pixel driving unit 200, thereby switching the display operating mode and detection operating mode of the composite functional sub-pixel Pf.

[0126] The driver circuit layer 02 may also include multiple data signal lines, multiple scan signal lines, multiple light emission control signal lines, and multiple power supply traces. (See reference) Figure 11 The pixel driving unit 200 includes a pixel circuit, which can be a conventional pixel circuit such as a "2T1C" circuit, a "7T1C" circuit, or an "8T1C" circuit. The pixel circuit is connected to scan signal lines, light emission control signal lines, data signal lines, and power supply lines. The data signal lines are configured to provide data voltage to the pixel circuit, the scan signal lines are configured to provide scan signals to the pixel circuit, the light emission control signal lines are configured to provide light emission control signals to the pixel circuit, and the power supply lines are configured to provide a first electrode voltage to the pixel circuit. In this embodiment, the first electrode 11 is an anode (Ad), and the second electrode 12 is a cathode (Cd), meaning the power supply lines are configured to provide an anode voltage to the pixel circuit.

[0127] The power supply traces include a first power supply voltage transmission line and a second power supply voltage transmission line. The pixel driving unit 200, connected to the single-function sub-pixel Pd, is electrically connected to the first power supply voltage transmission line and configured to provide a positive bias voltage to the single-function sub-pixel Pd using the first power supply voltage, thereby driving the single-function sub-pixel Pd to emit light. The pixel driving unit 200, connected to the composite-function sub-pixel Pf, integrates a voltage switching module for switching the electrical connection between the second power supply voltage transmission line and the first power supply voltage transmission line. When the voltage switching module is switched to connect to the first power supply voltage transmission line, the pixel driving unit 200 provides a positive bias voltage to the composite-function sub-pixel Pf using the first power supply voltage, driving the composite-function sub-pixel Pf to emit light; when the voltage switching module is switched to connect to the second power supply voltage transmission line, the pixel driving unit 200 provides a reverse bias voltage to the composite-function sub-pixel Pf using the second power supply voltage, enabling the composite-function sub-pixel Pf to perform photodetection. The control module has a built-in photocurrent-to-digital signal conversion unit, which can convert the photocurrent generated by the composite functional sub-pixel Pf in the detection mode into an 8-16 bit digital signal for fingerprint image reconstruction.

[0128] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A display screen, characterized in that, include: A driving substrate includes a substrate and a plurality of pixel driving units located on one side of the substrate; Multiple sub-pixels are arranged in the display area of ​​the driving substrate; each sub-pixel includes a first electrode, a light-emitting layer, and a second electrode that are sequentially located away from the driving substrate; the first electrode of each sub-pixel is electrically connected to a pixel driving unit. The control module is electrically connected to the pixel driving unit in the driving substrate; Wherein, at least a portion of the display area is a light detection area; a portion of the sub-pixels located in the light detection area are composite functional sub-pixels integrating sensing and display functions; the composite functional sub-pixel further includes a light detection layer located between the first electrode and the light-emitting layer or between the light-emitting layer and the second electrode; the control module is used to switch the voltage direction applied to the composite functional sub-pixel through the pixel driving unit to realize the switching between the light emission working mode and the light detection working mode of the composite functional sub-pixel.

2. The display screen according to claim 1, characterized in that, The photodetector layer includes: A first functional layer and a second functional layer are stacked together; the first functional layer is made of a P-type organic semiconductor material, and the second functional layer is made of an N-type organic semiconductor material. The first functional layer and the second functional layer are used to form a PN junction structure; when the composite functional sub-pixel is in the light-emitting working mode, the PN junction structure is used to transport charge carriers; when the composite functional sub-pixel is in the light-detecting working mode, the PN junction structure is used to detect fingerprint reflected light.

3. The display screen according to claim 2, characterized in that, The first electrode is the anode, and the second electrode is the cathode; When the photodetector layer is located between the first electrode and the light-emitting layer, the first functional layer is closer to the first electrode than the second functional layer; When the photodetector layer is located between the second electrode and the light-emitting layer, the second functional layer is closer to the second electrode than the first functional layer.

4. The display screen according to claim 1, characterized in that, The photodetector layer comprises a blend of P-type organic semiconductor materials and N-type organic semiconductor materials, wherein the P-type organic semiconductor materials and N-type organic semiconductor materials form a bulk heterojunction structure in the photodetector layer.

5. The display screen according to any one of claims 2 to 4, characterized in that, The p-type organic semiconductor material includes one or more of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate), poly3-hexylthiophene, and copper phthalocyanine. The N-type organic semiconductor material includes fullerene C. 60 One or more of perylenetetracarboxylic dianhydride and N,N'-dioctyl-3,4,9,10-perylenediimide.

6. The display screen according to any one of claims 2 to 4, characterized in that, When the photodetector layer is located between the first electrode and the light-emitting layer, the electron mobility of the bulk material of the light-emitting layer in the composite functional sub-pixel is greater than the hole mobility. When the photodetector layer is located between the second electrode and the light-emitting layer, the hole mobility of the bulk material of the light-emitting layer in the composite functional sub-pixel is greater than the electron mobility.

7. The display screen according to claim 1, characterized in that, The absolute value of the difference between the absorption wavelength and the emission wavelength of the composite functional sub-pixel is less than or equal to 30 nm.

8. The display screen according to claim 7, characterized in that, The plurality of sub-pixels includes red sub-pixels, green sub-pixels, and blue sub-pixels; the composite functional sub-pixel is one or more of the red sub-pixels, green sub-pixels, and blue sub-pixels; The absolute value of the difference between the absorption wavelength of the composite functional sub-pixel and the emission wavelength of the red sub-pixel is less than or equal to 30 nm; or the absolute value of the difference between the absorption wavelength of the composite functional sub-pixel and the emission wavelength of the green sub-pixel is less than or equal to 30 nm; or the absolute value of the difference between the absorption wavelength of the composite functional sub-pixel and the emission wavelength of the blue sub-pixel is less than or equal to 30 nm.

9. The display screen according to claim 1, characterized in that, The plurality of sub-pixels includes a plurality of composite function sub-pixels and a plurality of single function sub-pixels; the single function sub-pixels are configured to perform only the light-emitting function; At least the single-function sub-pixel also includes: At least one of a hole injection layer, a hole transport layer, and an electron blocking layer located between the first electrode and the light-emitting layer; and / or at least one of an electron injection layer, an electron transport layer, and a hole blocking layer located between the second electrode and the light-emitting layer; Wherein, the absolute value of the difference between the total film thickness between the first electrode and the light-emitting layer in the single-function sub-pixel and the total film thickness between the first electrode and the light-emitting layer in the composite-function sub-pixel is less than a preset difference.

10. The display screen according to claim 1, characterized in that, The multiple sub-pixels constitute multiple pixel units arranged in an array; each pixel unit includes a green emitting sub-pixel, a red emitting sub-pixel, and a blue emitting sub-pixel; In the light detection area, the number of composite functional sub-pixels in the pixel unit containing the composite functional sub-pixel is less than or equal to 2; and / or, each n×m pixel unit array has one pixel unit containing the composite functional sub-pixel, where n is the number of rows in the pixel unit array, m is the number of columns in the pixel unit array, n is an integer greater than or equal to 1, and m is an integer greater than or equal to 1.

11. The display screen according to claim 9, characterized in that, Also includes: A power supply module is configured to provide at least a first power supply voltage and a second power supply voltage to the sub-pixel array; wherein... The pixel driving unit connected to the single-function sub-pixel is electrically connected to a first power supply voltage transmission line and is configured to provide a positive bias voltage to the single-function sub-pixel using the first power supply voltage. The pixel driving unit connected to the composite functional sub-pixel integrates a voltage switching module and is electrically connected to a second power supply voltage transmission line and a first power supply voltage transmission line. The voltage switching module is configured to provide a reverse bias voltage to the composite functional sub-pixel using the second power supply voltage and to provide a forward bias voltage to the composite functional sub-pixel using the first power supply voltage. The control module is configured to output synchronization control signals to the plurality of independent pixel driving units so that the composite functional sub-pixels and the single functional sub-pixels can work together.

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