WO2022226718A1 - 有机电致发光器件及其制备方法、显示装置 - Google Patents

有机电致发光器件及其制备方法、显示装置 Download PDF

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Publication number
WO2022226718A1
WO2022226718A1 PCT/CN2021/089833 CN2021089833W WO2022226718A1 WO 2022226718 A1 WO2022226718 A1 WO 2022226718A1 CN 2021089833 W CN2021089833 W CN 2021089833W WO 2022226718 A1 WO2022226718 A1 WO 2022226718A1
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Prior art keywords
electron transport
layer
transport layer
light
host material
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PCT/CN2021/089833
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English (en)
French (fr)
Inventor
张智辉
樊燕
樊星
景姝
刘华猛
沈阔
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京东方科技集团股份有限公司
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Priority to US17/638,195 priority Critical patent/US20240057363A1/en
Priority to PCT/CN2021/089833 priority patent/WO2022226718A1/zh
Priority to CN202180000908.0A priority patent/CN115529845A/zh
Publication of WO2022226718A1 publication Critical patent/WO2022226718A1/zh

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/14—Carrier transporting layers
    • H10K50/16—Electron transporting layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/80—Constructional details
    • H10K50/85—Arrangements for extracting light from the devices
    • H10K50/858—Arrangements for extracting light from the devices comprising refractive means, e.g. lenses
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/80—Constructional details
    • H10K59/805—Electrodes
    • H10K59/8051—Anodes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
    • H10K71/10—Deposition of organic active material
    • H10K71/12—Deposition of organic active material using liquid deposition, e.g. spin coating
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/80—Composition varying spatially, e.g. having a spatial gradient
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/90—Multiple hosts in the emissive layer
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
    • H10K2102/301—Details of OLEDs
    • H10K2102/351—Thickness

Definitions

  • the present disclosure relates to, but is not limited to, the field of display technology, and in particular, to an organic electroluminescence device, a method for preparing the same, and a display device.
  • OLED Organic Light Emitting Device
  • TFTs thin film transistors
  • OLED includes an anode, a cathode, and a light-emitting layer arranged between the anode and the cathode.
  • the light-emitting principle is to inject holes and electrons into the light-emitting layer from the anode and the cathode, respectively.
  • the electrons and holes meet in the light-emitting layer, the electrons and The holes recombine to generate excitons, which emit light while transitioning from an excited state to a ground state.
  • a hole injection layer and a hole transport layer are arranged between the anode and the light-emitting layer, and an electron injection layer is arranged between the cathode and the light-emitting layer. layer and electron transport layer.
  • the design of the electron transport layer is more important.
  • exemplary embodiments of the present disclosure provide an organic electroluminescent device including an anode, a cathode, and a light-emitting layer and an electron transport layer disposed between the anode and the cathode, the electron transport layer disposed on the between the light-emitting layer and the cathode; the electron transport layer includes a first host material and a second host material, and the mixing ratios of the first host material and the second host material on the side of the electron transport layer close to the light-emitting layer are different The mixing ratio of the first host material and the second host material on the side away from the light-emitting layer in the electron transport layer.
  • the refractive index of the first host material is greater than the refractive index of the second host material.
  • the mass percentage of the first host material in the electron transport layer gradually decreases along the direction from being close to the light-emitting layer to being away from the light-emitting layer, and the mass percentage of the second host material in the electron transport layer is gradually reduced. The mass percentage gradually increases.
  • the mass percentage of the first host material in the electron transport layer is 60% to 80%, and the mass percentage of the second host material in the electron transport layer is 60% to 80%.
  • the mass percentage of the material is 20% to 40%.
  • the mass percentage of the first host material in the electron transport layer is 0 to 10%
  • the mass percentage of the second host material in the electron transport layer is 0 to 10%.
  • the light emitting layer has a thickness of 10 nm to 25 nm
  • the electron transport layer has a thickness of 20 nm to 50 nm
  • the electron transport layer The refractive index is 1.80 to 2.00.
  • the thickness of the electron transport layer is 20 nm to 50 nm
  • the thickness of the cathode is 10 nm to 20 nm
  • the refraction of the electron transport layer The rate is 1.55 to 1.70.
  • a hole injection layer, a hole transport layer and an electron blocking layer are further arranged between the anode and the light emitting layer, and a hole blocking layer is further arranged between the light emitting layer and the electron transport layer,
  • An electron injection layer is also arranged between the electron transport layer and the cathode; the thickness of the hole injection layer is 5nm to 20nm, the thickness of the hole transport layer is 100nm to 150nm, and the thickness of the electron blocking layer is 5nm to 20nm, the light emitting layer has a thickness of 10nm to 25nm, the hole blocking layer has a thickness of 5nm to 15nm, and the electron injection layer has a thickness of 0.5nm to 2nm;
  • the electron transport layer On one side of the hole blocking layer, the electron transport layer has a refractive index of 1.80 to 2.00, and on the side of the electron transport layer close to the electron injection layer, the electron transport layer has a refractive index of 1.55 to 1.70.
  • the electron transport layer has a maximum refractive index n RMAX for red light in a wavelength range of 600 nm to 640 nm, a maximum green refractive index n GMAX in a wavelength range of 510 nm to 550 nm, and a maximum refractive index for green light in the wavelength range of 440 nm to 480 nm. has a maximum blue refractive index n BMAX ; the electron transport layer satisfies:
  • the maximum red refractive index n RMAX is 1.81 to 1.91
  • the maximum green refractive index n GMAX is 1.86 to 1.96
  • the maximum blue refractive index n BMAX is 1.90 to 2.00.
  • the electron transport layer has a minimum refractive index n RMIN for red light in a wavelength range of 600 nm to 640 nm, a minimum refractive index for green light n GMIN in a wavelength range of 510 nm to 550 nm, and a minimum refractive index for green light in the wavelength range of 440 nm to 480 nm. has a minimum blue refractive index n BMIN ; the electron transport layer satisfies:
  • the minimum red refractive index n RMIN is 1.55 to 1.65
  • the minimum green refractive index n GMIN is 1.57 to 1.67
  • the minimum blue refractive index n BMIN is 1.60 to 1.70.
  • an exemplary embodiment of the present disclosure also provides a display device including the aforementioned organic electroluminescence device.
  • an exemplary embodiment of the present disclosure also provides a method for fabricating an organic electroluminescent device, including:
  • An electron transport layer is formed, the electron transport layer includes a first host material and a second host material, and the mixing ratio of the first host material and the second host material on the side close to the light-emitting layer in the electron transport layer is different from that of the the mixing ratio of the first host material and the second host material on the side away from the light-emitting layer in the electron transport layer;
  • forming the electron transport layer includes: using a co-evaporation method of a first host material source and a second host material source, and during the process from the start of the evaporation to the end of the evaporation, controlling the amount of the first host material.
  • the evaporation rate is gradually decreased, and the evaporation rate of the second host material is gradually increased, so that the mass percentage of the first host material in the electron transport layer is gradually increased along the direction from being close to the light-emitting layer to being away from the light-emitting layer. Decrease, the mass percentage of the second host material in the electron transport layer gradually increases.
  • the evaporation rate of the first host material is controlled to be to The evaporation rate of the second host material is controlled to be to At the end of the evaporation, the evaporation rate of the first host material is controlled to be 0 to The evaporation rate of the second host material is controlled to be to
  • 1 is a schematic structural diagram of a display device
  • FIG. 2 is a schematic plan view of a display device
  • FIG. 3 is a schematic diagram of an equivalent circuit of a pixel driving circuit
  • FIG. 4 is a working timing diagram of a pixel driving circuit
  • FIG. 5 is a schematic cross-sectional structure diagram of a display device
  • FIG. 6 is a schematic structural diagram of a light-emitting device according to an exemplary embodiment of the present disclosure.
  • FIG. 7 is a schematic structural diagram of another light-emitting device according to an exemplary embodiment of the present disclosure.
  • FIG. 8 is a comparison result of light extraction efficiency of a comparative structure of an exemplary embodiment of the present disclosure.
  • 9a to 9c are diagrams of mode ratio distributions of light emitting devices according to exemplary embodiments of the present disclosure.
  • 10 anode
  • 20 hole injection layer
  • 30 hole transport layer
  • 70 electron transport layer
  • 80 electron injection layer
  • 90 cathode
  • 101 substrate
  • 102 drive circuit layer
  • 103 light emitting structure layer.
  • 104 package layer
  • 210 drive transistor
  • 211 storage capacitor
  • 301 anode
  • 302 pixel definition layer
  • 303 organic light-emitting layer
  • 304 cathode
  • 401 first encapsulation layer
  • 402 second encapsulation layer
  • the terms “installed”, “connected” and “connected” should be construed broadly unless otherwise expressly specified and limited. For example, it may be a fixed connection, or a detachable connection, or an integral connection; it may be a mechanical connection, or an electrical connection; it may be a direct connection, or an indirect connection through an intermediate piece, or an internal communication between two elements.
  • installed may be a fixed connection, or a detachable connection, or an integral connection; it may be a mechanical connection, or an electrical connection; it may be a direct connection, or an indirect connection through an intermediate piece, or an internal communication between two elements.
  • a transistor refers to an element including at least three terminals of a gate electrode, a drain electrode, and a source electrode.
  • the transistor has a channel region between the drain electrode (or drain electrode terminal, drain region or drain electrode) and the source electrode (or source electrode terminal, source region or source electrode), and current can flow through the drain electrode, channel region and source electrode.
  • the channel region refers to a region through which current mainly flows.
  • the first electrode may be the drain electrode and the second electrode may be the source electrode, or the first electrode may be the source electrode and the second electrode may be the drain electrode.
  • the functions of the "source electrode” and the “drain electrode” may be interchanged. Therefore, herein, “source electrode” and “drain electrode” may be interchanged with each other.
  • electrically connected includes the case where constituent elements are connected together by means of elements having some electrical function.
  • the "element having a certain electrical effect” is not particularly limited as long as it can transmit and receive electrical signals between the connected constituent elements.
  • the “element having a certain electrical effect” may be, for example, electrodes or wirings, or switching elements such as transistors, or other functional elements such as resistors, inductors, and capacitors.
  • parallel refers to a state where the angle formed by two straight lines is -10° or more and 10° or less, and therefore, also includes a state where the angle is -5° or more and 5° or less.
  • perpendicular refers to the state where the angle formed by two straight lines is 80° or more and 100° or less, and therefore includes the state where the angle is 85° or more and 95° or less.
  • film and “layer” are interchangeable.
  • conductive layer may be replaced by “conductive film” in some cases.
  • insulating film may be replaced with “insulating layer” in some cases.
  • FIG. 1 is a schematic structural diagram of a display device.
  • the OLED display device may include a timing controller, a data signal driver, a scan signal driver, a light-emitting signal driver, and a pixel array
  • the pixel array may include a plurality of scan signal lines (S1 to Sm), a plurality of data signal lines (D1 to Dn), a plurality of light-emitting signal lines (E1 to Eo), and a plurality of sub-pixels Pxij.
  • the timing controller may supply a grayscale value and a control signal suitable for the specification of the data signal driver to the data signal driver, and may supply a clock signal, a scan start signal, etc., suitable for the specification of the scan signal driver When supplied to the scan signal driver, a clock signal, an emission stop signal, and the like suitable for the specifications of the light-emitting signal driver can be supplied to the light-emitting signal driver.
  • the data signal driver may generate data voltages to be supplied to the data signal lines D1 , D2 , D3 , . . . and Dn using the grayscale values and control signals received from the timing controller.
  • the data signal driver may sample grayscale values with a clock signal and apply data voltages corresponding to the grayscale values to the data signal lines D1 to Dn in pixel row units, where n may be a natural number.
  • the scan signal driver may generate scan signals to be supplied to the scan signal lines S1 , S2 , S3 , . . . and Sm by receiving a clock signal, a scan start signal, and the like from the timing controller.
  • the scan signal driver may sequentially supply scan signals having on-level pulses to the scan signal lines S1 to Sm.
  • the scan signal driver may be constructed in the form of a shift register, and may generate scans in such a manner that a scan start signal supplied in the form of an on-level pulse is sequentially transmitted to the next stage circuit under the control of a clock signal signal, m can be a natural number.
  • the emission signal driver may generate emission signals to be supplied to the emission signal lines E1 , E2 , E3 , . . . and Eo by receiving a clock signal, an emission stop signal, and the like from the timing controller.
  • the emission signal driver may sequentially supply emission signals having off-level pulses to the emission signal lines E1 to Eo.
  • the light-emitting signal driver may be constructed in the form of a shift register, and may generate the light-emitting signal in such a manner that the light-emitting stop signal provided in the form of an off-level pulse is sequentially transmitted to the next stage circuit under the control of the clock signal, o can be a natural number.
  • the pixel array may include a plurality of sub-pixels Pxij. Each sub-pixel Pxij may be connected to a corresponding data signal line, a corresponding scan signal line, and a corresponding light-emitting signal line, and i and j may be natural numbers.
  • the sub-pixel Pxij may refer to a sub-pixel in which a transistor is connected to the i-th scan signal line and to the j-th data signal line.
  • FIG. 2 is a schematic plan view of a display device.
  • the display device may include a plurality of pixel units P arranged in a matrix, and at least one of the plurality of pixel units P includes a first sub-pixel that emits light of a first color P1, the second sub-pixel P2 that emits light of the second color, and the third sub-pixel P3 that emits light of the third color, the first sub-pixel P1, the second sub-pixel P2 and the third sub-pixel P3 all include a pixel driving circuit and a light-emitting device.
  • the pixel driving circuits in the first sub-pixel P1, the second sub-pixel P2 and the third sub-pixel P3 are respectively connected to the scanning signal line, the data signal line and the light-emitting signal line, and the pixel driving circuit is configured to connect the scanning signal line and the light-emitting signal line. Under the control of the line, the data voltage transmitted by the data signal line is received, and the corresponding current is output to the light-emitting device.
  • the light-emitting devices in the first sub-pixel P1, the second sub-pixel P2, and the third sub-pixel P3 are respectively connected to the pixel driving circuit of the sub-pixel, and the light-emitting device is configured to respond to the current output by the pixel driving circuit of the sub-pixel. Brightness of light.
  • the pixel unit P may include red (R) sub-pixels, green (G) sub-pixels, and blue (B) sub-pixels, or may include red sub-pixels, green sub-pixels, and blue sub-pixels and white sub-pixels, which are not limited in this disclosure.
  • the shape of the sub-pixels in the pixel unit may be rectangular, diamond, pentagon or hexagonal.
  • the pixel unit includes three sub-pixels, the three sub-pixels can be arranged horizontally, vertically, or in a zigzag manner.
  • the pixel unit includes four sub-pixels, the four sub-pixels can be arranged in a horizontal, vertical, or square manner. The arrangement is not limited in this disclosure.
  • the pixel driving circuit may be a 3T1C, 4T1C, 5T1C, 5T2C, 6T1C or 7T1C structure.
  • FIG. 3 is a schematic diagram of an equivalent circuit of a pixel driving circuit. As shown in FIG. 3, the pixel driving circuit may include 7 transistors (the first transistor T1 to the seventh transistor T7), 1 storage capacitor C, and 7 signal lines (the data signal line D, the first scan signal line S1, the Two scan signal lines S2, light-emitting signal lines E, initial signal lines INIT, first power lines VDD and second power lines VSS).
  • the first end of the storage capacitor C is connected to the first power supply line VDD
  • the second end of the storage capacitor C is connected to the second node N2, that is, the second end of the storage capacitor C is connected to the third transistor T3 Control pole connection.
  • the control electrode of the first transistor T1 is connected to the second scan signal line S2, the first electrode of the first transistor T1 is connected to the initial signal line INIT, and the second electrode of the first transistor is connected to the second node N2.
  • the first transistor T1 transmits an initialization voltage to the gate of the third transistor T3 to initialize the charge amount of the gate of the third transistor T3.
  • the control electrode of the second transistor T2 is connected to the first scan signal line S1, the first electrode of the second transistor T2 is connected to the second node N2, and the second electrode of the second transistor T2 is connected to the third node N3.
  • the second transistor T2 connects the control electrode of the third transistor T3 to the second electrode.
  • the control electrode of the third transistor T3 is connected to the second node N2, that is, the control electrode of the third transistor T3 is connected to the second end of the storage capacitor C, the first electrode of the third transistor T3 is connected to the first node N1, and the third transistor T3 is connected to the first node N1.
  • the second pole of T3 is connected to the third node N3.
  • the third transistor T3 may be referred to as a driving transistor, and the third transistor T3 determines the amount of driving current flowing between the first power supply line VDD and the second power supply line VSS according to the potential difference between its control electrode and the first electrode.
  • the control electrode of the fourth transistor T4 is connected to the first scan signal line S1, the first electrode of the fourth transistor T4 is connected to the data signal line D, and the second electrode of the fourth transistor T4 is connected to the first node N1.
  • the fourth transistor T4 may be referred to as a switching transistor, a scan transistor, or the like, and enables the data voltage of the data signal line D to be input to the pixel driving circuit when an on-level scan signal is applied to the first scan signal line S1.
  • the control electrode of the fifth transistor T5 is connected to the light-emitting signal line E, the first electrode of the fifth transistor T5 is connected to the first power line VDD, and the second electrode of the fifth transistor T5 is connected to the first node N1.
  • the control electrode of the sixth transistor T6 is connected to the light emitting signal line E, the first electrode of the sixth transistor T6 is connected to the third node N3, and the second electrode of the sixth transistor T6 is connected to the first electrode of the light emitting device.
  • the fifth transistor T5 and the sixth transistor T6 may be referred to as light emitting transistors. When an on-level light emission signal is applied to the light emission signal line E, the fifth and sixth transistors T5 and T6 make the light emitting device emit light by forming a driving current path between the first power supply line VDD and the second power supply line VSS.
  • the control electrode of the seventh transistor T7 is connected to the first scan signal line S1, the first electrode of the seventh transistor T7 is connected to the initial signal line INIT, and the second electrode of the seventh transistor T7 is connected to the first electrode of the light emitting device.
  • the seventh transistor T7 transmits an initialization voltage to the first electrode of the light emitting device to initialize or discharge the amount of charge accumulated in the first electrode of the light emitting device to emit light The amount of charge accumulated in the first pole of the device.
  • the second pole of the light emitting device is connected to the second power supply line VSS, the signal of the second power supply line VSS is a low-level signal, and the signal of the first power supply line VDD is a continuous high-level signal.
  • the first scan signal line S1 is the scan signal line in the pixel driving circuit of the display row
  • the second scan signal line S2 is the scan signal line in the pixel driving circuit of the previous display row, that is, for the nth display row, the first scan signal
  • the line S1 is S(n)
  • the second scanning signal line S2 is S(n-1)
  • the second scanning signal line S2 of this display line is the same as the first scanning signal line S1 in the pixel driving circuit of the previous display line
  • the signal lines can reduce the signal lines of the display panel and realize the narrow frame of the display panel.
  • the first to seventh transistors T1 to T7 may be P-type transistors, or may be N-type transistors. Using the same type of transistors in the pixel driving circuit can simplify the process flow, reduce the process difficulty of the display panel, and improve the product yield. In some possible implementations, the first to seventh transistors T1 to T7 may include P-type transistors and N-type transistors.
  • the first scan signal line S1, the second scan signal line S2, the light emitting signal line E and the initial signal line INIT extend in the horizontal direction
  • the second power supply line VSS, the first power supply line VDD and the data signal line D extends in the vertical direction.
  • the light emitting device may be an organic electroluminescent diode (OLED) including a stacked first electrode (anode), an organic light emitting layer and a second electrode (cathode).
  • OLED organic electroluminescent diode
  • FIG. 4 is a working timing diagram of a pixel driving circuit. Exemplary embodiments of the present disclosure will be described below through the operation process of the pixel driving circuit exemplified in FIG. 3 .
  • the pixel driving circuit in FIG. 3 includes 7 transistors (the first transistor T1 to the sixth transistor T7 ), 1 storage capacitors C and 7 signal lines (data signal line D, first scan signal line S1, second scan signal line S2, light-emitting signal line E, initial signal line INIT, first power supply line VDD and second power supply line VSS), all seven transistors are is a P-type transistor.
  • the working process of the pixel driving circuit may include:
  • the signal of the second scanning signal line S2 is a low-level signal, and the signals of the first scanning signal line S1 and the light-emitting signal line E are a high-level signal.
  • the signal of the second scanning signal line S2 is a low level signal, which turns on the first transistor T1, and the signal of the initial signal line INIT is supplied to the second node N2 to initialize the storage capacitor C and clear the original data voltage in the storage capacitor.
  • the signals of the first scanning signal line S1 and the light-emitting signal line E are high-level signals, so that the second transistor T2, the fourth transistor T4, the fifth transistor T5, the sixth transistor T6 and the seventh transistor T7 are turned off. At this stage, the OLED Not glowing.
  • the second stage A2 is called the data writing stage or the threshold compensation stage.
  • the signal of the first scanning signal line S1 is a low-level signal
  • the signals of the second scanning signal line S2 and the light-emitting signal line E are a high-level signal
  • the data The signal line D outputs the data voltage.
  • the third transistor T3 is turned on.
  • the signal of the first scan signal line S1 is a low level signal, so that the second transistor T2, the fourth transistor T4 and the seventh transistor T7 are turned on.
  • the second transistor T2 and the fourth transistor T4 are turned on so that the data voltage output from the data signal line D is supplied to the second through the first node N1, the turned-on third transistor T3, the third node N3, and the turned-on second transistor T2 node N2, and the difference between the data voltage output by the data signal line D and the threshold voltage of the third transistor T3 is charged into the storage capacitor C, and the voltage of the second end (second node N2) of the storage capacitor C is Vd-
  • the seventh transistor T7 is turned on so that the initial voltage of the initial signal line INIT is supplied to the first electrode of the OLED, initializes (resets) the first electrode of the OLED, clears the internal pre-stored voltage, completes the initialization, and ensures that the OLED does not emit light.
  • the signal of the second scanning signal line S2 is a high-level signal, so that the first transistor T1 is turned off.
  • the signal of the light-emitting signal line E is a high-level signal, so that the fifth transistor T5 and the sixth transistor T6 are turned off.
  • the third stage A3 is called the light-emitting stage, the signal of the light-emitting signal line E is a low-level signal, and the signals of the first scanning signal line S1 and the second scanning signal line S2 are high-level signals.
  • the signal of the light-emitting signal line E is a low-level signal, so that the fifth transistor T5 and the sixth transistor T6 are turned on, and the power supply voltage output by the first power line VDD passes through the fifth transistor T5, the third transistor T3 and the sixth transistor T5, which are turned on.
  • the transistor T6 provides a driving voltage to the first electrode of the OLED to drive the OLED to emit light.
  • the driving current flowing through the third transistor T3 (driving transistor) is determined by the voltage difference between its gate electrode and the first electrode. Since the voltage of the second node N2 is Vdata-
  • I is the driving current flowing through the third transistor T3, that is, the driving current for driving the OLED
  • K is a constant
  • Vgs is the voltage difference between the gate electrode and the first electrode of the third transistor T3
  • Vth is the third transistor.
  • Vd is the data voltage output by the data signal line D
  • Vdd is the power supply voltage output by the first power line VDD.
  • FIG. 5 is a schematic cross-sectional structure diagram of a display device, illustrating the structure of three sub-pixels of the OLED display device.
  • the display device may include a driving circuit layer 102 disposed on a substrate 101, a light emitting structure layer 103 disposed on a side of the driving circuit layer 102 away from the substrate 101, and a light emitting structure layer 103 disposed on the light emitting
  • the structure layer 103 is away from the encapsulation layer 104 on the side of the substrate 101 .
  • the display device may include other film layers, such as spacer columns, etc., which are not limited in the present disclosure.
  • the substrate may be a flexible substrate, or it may be a rigid substrate.
  • the flexible substrate may include a stacked first flexible material layer, a first inorganic material layer, a semiconductor layer, a second flexible material layer and a second inorganic material layer, and the materials of the first flexible material layer and the second flexible material layer may be made of polymer.
  • the materials of the first inorganic material layer and the second inorganic material layer can be silicon nitride (SiNx ) or silicon oxide (SiOx), etc., to improve the water and oxygen resistance of the substrate, and the material of the semiconductor layer can be amorphous silicon (a-si), polycrystalline silicon (p-si) or oxide (Oxide).
  • PI imide
  • PET polyethylene terephthalate
  • SiOx silicon oxide
  • the material of the semiconductor layer can be amorphous silicon (a-si), polycrystalline silicon (p-si) or oxide (Oxide).
  • the driving circuit layer 102 of each sub-pixel may include a plurality of transistors and storage capacitors constituting a pixel driving circuit, and only one driving transistor and one storage capacitor are used as an example for illustration in FIG. 5 .
  • the driving circuit layer 102 of each sub-pixel may include: a first insulating layer disposed on the substrate; an active layer disposed on the first insulating layer; and a second insulating layer covering the active layer The gate electrode and the first capacitor electrode arranged on the second insulating layer; the third insulating layer covering the gate electrode and the first capacitor electrode; the second capacitor electrode arranged on the third insulating layer; The fourth insulating layer, the second insulating layer, the third insulating layer and the fourth insulating layer are provided with via holes, and the via holes expose the active layer; the source electrode and the drain electrode arranged on the fourth insulating layer, the source electrode and the The drain electrodes are respectively connected with the active layer through via holes; the flat layer covering the aforementioned structure
  • the light emitting structure layer 103 includes a light emitting device that makes organic materials emit light under the action of an electric field, and the light emitting structure layer 103 may include an anode 301 , a pixel definition layer 302 , an organic light emitting layer 303 and a cathode 304 .
  • the anode 301 is arranged on the flat layer 205 and is connected to the drain electrode of the driving transistor 210 through a via hole opened on the flat layer 205;
  • the pixel definition layer 302 is arranged on the anode 301 and the flat layer 205, and a pixel opening is arranged on the pixel definition layer 302 , the pixel opening exposes the anode 301;
  • the organic light-emitting layer 303 is at least partially disposed in the pixel opening, and the organic light-emitting layer 303 is connected to the anode 301;
  • the cathode 304 is disposed on the organic light-emitting layer 303, and the cathode 304 is connected to the organic light-emitting layer 303;
  • the layer 303 is driven by the anode 301 and the cathode 304 to emit light of the corresponding color.
  • the encapsulation layer 104 may include a stacked first encapsulation layer 401, a second encapsulation layer 402 and a third encapsulation layer 403.
  • the first encapsulation layer 401 and the third encapsulation layer 403 may be made of inorganic materials.
  • the second encapsulation layer 402 can be made of organic materials, and the second encapsulation layer 402 is disposed between the first encapsulation layer 401 and the third encapsulation layer 403 to ensure that the outside water vapor cannot enter the light emitting structure layer 103 .
  • the organic light-emitting layer of the OLED light-emitting device may include an emission layer (Emitting Layer, referred to as EML), and include any one or more of the following: a hole injection layer (Hole Injection Layer, referred to as HIL), empty Hole Transport Layer (HTL), Hole Block Layer (HBL), Electron Block Layer (EBL), Electron Injection Layer (EIL), Electron Block Layer Transport layer (Electron Transport Layer, referred to as ETL).
  • HIL hole injection layer
  • HTL Hole Transport Layer
  • HBL Hole Block Layer
  • EBL Electron Block Layer
  • EIL Electron Block Layer Transport Layer
  • ETL Electron Block Layer Transport Layer
  • the light-emitting layers of the OLED light-emitting devices of different colors are different.
  • a red light-emitting device includes a red light-emitting layer
  • a green light-emitting device includes a green light-emitting layer
  • a blue light-emitting device includes a blue light-emitting layer.
  • the hole injection layer and the hole transport layer on one side of the light emitting layer can use a common layer
  • the electron injection layer and the electron transport layer on the other side of the light emitting layer can use a common layer.
  • any one or more of the hole injection layer, hole transport layer, electron injection layer, and electron transport layer may be fabricated by one process (one evaporation process or one inkjet printing process), However, isolation is achieved by the surface step difference of the formed film layer or by means of surface treatment.
  • any one or more of the hole injection layer, hole transport layer, electron injection layer and electron transport layer corresponding to adjacent sub-pixels may be isolated.
  • the organic light emitting layer may be formed by an evaporation process or an inkjet process.
  • OLED display devices can be divided into two types: bottom emission OLED and top emission OLED.
  • top-emitting OLEDs have the characteristics of improving luminous efficiency and color purity, and the enhancement of display effect is obvious, there are also losses such as internal optical waveguides, surface plasmons, and non-radiative dissipation, which reduce the light extraction efficiency.
  • an external light extraction structure is usually arranged, for example, a light output coupling layer is arranged on a translucent cathode, or a high refractive index layer is arranged on the surface of the translucent cathode. the dielectric.
  • FIG. 6 is a schematic structural diagram of a light emitting device according to an exemplary embodiment of the present disclosure.
  • the light-emitting device is an organic electroluminescent device, which may include an anode 10 , a cathode 90 and an organic light-emitting layer disposed between the anode 10 and the cathode 90 .
  • the organic light emitting layer may include a stacked light emitting layer (EML) 50 and an electron transport layer (ETL) 70 disposed between the light emitting layer 50 and the cathode 90 .
  • EML electron emitting layer
  • ETL electron transport layer
  • the light emitting layer 50 is configured to recombine electrons and holes to emit light
  • the electron transport layer 70 is configured to enable controlled migration of the directional ordering of injected electrons.
  • the electron transport layer may include at least a first host material and a second host material, and along the direction from the light emitting layer 50 to the cathode 90, the mass percentage of the first host material in the electron transport layer gradually decreases, and the electron transports The mass percentage of the second host material in the layer is gradually increased.
  • the first host material and the second host material may satisfy:
  • N 1 is the refractive index of the first host material
  • N 2 is the refractive index of the second host material.
  • the refractive index N 1 of the first host material may be about 1.8 (@460 nm)
  • the refractive index N 2 of the second host material may be about 1.6 (@460 nm).
  • the refractive index of the material can be measured using an ellipsometer device, with @460nm representing the refractive index measured at a wavelength of 460nm.
  • the electron transport layer may have a refractive index of about 1.80 to 2.00 on the first side of the electron transport layer close to the light emitting layer.
  • the electron transport layer may have a refractive index of about 1.55 to 1.70 on the second side of the electron transport layer away from the light emitting layer (near the cathode).
  • the thickness of the electron transport layer may be about 20 nm to 50 nm.
  • the first host material and the second host material may include, but are not limited to, the following materials: 8-hydroxyquinoline aluminum (Alq3), 4,7-diphenyl-1,10-phenanthroline (BPhen), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI).
  • Alq3 8-hydroxyquinoline aluminum
  • BPhen 4,7-diphenyl-1,10-phenanthroline
  • TPBI 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene
  • the first host material and the second host material can be co-evaporated, so that the first host material and the second host material are uniformly dispersed in the electron transport layer.
  • the mixing ratio is regulated by the evaporation rate of the first host material and the evaporation rate of the second host material.
  • the evaporation rate of the first host material is controlled to be about Controlling the evaporation rate of the second host material is about It is realized that the mass percentage of the first host material in the electron transport layer is about 30%, and the mass percentage of the second host material in the electron transport layer is about 70%.
  • the electron transport layer typically has a fixed refractive index.
  • a light wave electromagnetic wave
  • the free electrons on the metal surface collectively oscillate, and the electromagnetic wave is coupled with the free electrons on the metal surface to form a near-field electromagnetic wave that propagates along the metal surface.
  • Resonance occurs when the frequency of the incident light wave is consistent.
  • the energy of the electromagnetic field is effectively converted into the collective vibration energy of free electrons on the metal surface.
  • a special electromagnetic mode is formed: the electromagnetic field is confined to the metal surface. This phenomenon is called the Surface Plasmon Polariton (SPP) effect, which reduces the output light efficiency.
  • SPP Surface Plasmon Polariton
  • the electron transport layer In order to reduce the surface plasmon phenomenon between the electron transport layer and the cathode to reduce light loss, the electron transport layer needs to use a material with a smaller refractive index. However, the reflection effect of the film layer between the electron transport layer with the smaller refractive index and the light-emitting layer is low, which reduces the microcavity effect of the overall device and reduces the light extraction efficiency of the light-emitting device. In order to improve the film reflection effect between the electron transport layer and the light-emitting layer, the electron transport layer needs to use a material with a larger refractive index.
  • the electron transport layer of the exemplary embodiment of the present disclosure is formed by mixing a first host material and a second host material with different refractive indices, and the mixing ratio of the first host material and the second host material is different at different positions, and the electron transport layer is close to
  • the refractive index on the side of the light-emitting layer is greater than the refractive index on the side far from the light-emitting layer in the electron transport layer, which maximizes the matching of the refractive indices in the multi-layer system, optimizes the optical performance of the light-emitting device, and effectively improves the light-emitting
  • the coupling-out light efficiency inside the device is more conducive to exerting the light-emitting characteristics of the device.
  • the surface plasmon phenomenon between the electron transport layer and the cathode is effectively reduced, and light loss is reduced.
  • the refractive index of the electron transport layer on the side close to the light-emitting layer is effectively improved, and the microcavity effect of the overall device is enhanced.
  • the exemplary embodiment of the present disclosure maximizes the matching of refractive indices in the multi-film system, optimizes the optical performance of the light-emitting device, effectively improves the efficiency of coupling out light inside the light-emitting device, and is more conducive to exerting the light output of the device. characteristic.
  • the light-emitting layer may be a red light-emitting layer, or may be a green light-emitting layer, or may be a blue light-emitting layer.
  • the overall performance of the light-emitting device can be better improved.
  • FIG. 7 is a schematic structural diagram of another light emitting device according to an exemplary embodiment of the present disclosure.
  • the light-emitting device is an organic electroluminescent device, which may include an anode 10 , a cathode 90 and an organic light-emitting layer disposed between the anode 10 and the cathode 90 .
  • the organic light emitting layer may include a stacked hole injection layer 20 , a hole transport layer 30 , an electron blocking layer 40 , a light emitting layer 50 , a hole blocking layer 60 , an electron transport layer 70 and an electron injection layer 80.
  • the hole injection layer 20, the hole transport layer 30 and the electron blocking layer 40 are arranged between the anode 10 and the light emitting layer 50, the hole injection layer 20 is connected to the anode 10, the electron blocking layer 40 is connected to the light emitting layer 50, and the hole transports Layer 30 is disposed between hole injection layer 20 and electron blocking layer 40 .
  • the hole blocking layer 60, the electron transport layer 70 and the electron injection layer 80 are arranged between the light emitting layer 50 and the cathode 90, the hole blocking layer 60 is connected with the light emitting layer 50, the electron injection layer 80 is connected with the cathode 90, and the electron transport layer 70 It is provided between the electron injection layers 80 .
  • the hole injection layer 20 is configured to lower a barrier for hole injection from the anode, enabling efficient injection of holes from the anode into the light emitting layer 50 .
  • the hole transport layer 30 is configured to achieve controlled migration of the directional order of the injected holes.
  • the electron blocking layer 40 is configured to form a migration barrier for electrons, preventing electrons from migrating out of the light emitting layer 50 .
  • the light-emitting layer 50 is configured to recombine electrons and holes to emit light.
  • the hole blocking layer 60 is configured to form a migration barrier for holes, preventing the holes from migrating out of the light emitting layer 50 .
  • Electron transport layer 70 is configured to achieve controlled migration of the directional order of injected electrons.
  • the electron injection layer 80 is configured to lower a barrier for injecting electrons from the cathode, so that electrons can be efficiently injected from the cathode to the light-emitting layer 50 .
  • the material and structure of the electron transport layer 70 are the same as or similar to those of the previous embodiments.
  • the refractive index of the electron transport layer 70 It may be about 1.80 to 2.00, and the electron transport layer 70 may have a refractive index of about 1.55 to 1.70 on the side of the electron transport layer 70 close to the electron injection layer 80 .
  • the anode may employ a metal or metal oxide material with a high work function.
  • the anode can be made of a transparent oxide material, such as indium tin oxide (ITO) or indium zinc oxide (IZO), and the thickness of the anode can be about 80 nm to 200 nm.
  • the anode can be made of metal materials, such as silver (Ag), gold (Au) or their alloys, etc., or a composite structure of metals and transparent oxides, such as Ag/ITO, Ag/IZO or ITO/ Ag/ITO, etc.
  • the thickness of the metal layer in the anode can be about 80nm to 100nm
  • the thickness of the transparent oxide in the anode can be about 5nm to 20nm, so that the average reflectivity of the anode in the visible light region is about 85% to 95%, starting from to the role of the total reflection anode.
  • the cathode may be made of a metal material, which may be formed by an evaporation process, and the metal material may be magnesium (Mg), silver (Ag), or aluminum (Al), or an alloy material such as
  • Mg:Ag alloys the ratio of Mg:Ag is about 9:1 to 1:9, and the thickness of the cathode can be about 10nm to 20nm, so that the average transmittance of the cathode at a wavelength of 530nm is about 50% to 60%. to the effect of semi-permeability and semi-reflection.
  • the cathode can be magnesium (Mg), silver (Ag), aluminum (Al) or Mg:Ag alloy, and the thickness of the cathode can be greater than 80nm, so that the cathode has good reflectivity and achieves total reflection The role of the cathode.
  • the hole injection layer may employ inorganic oxides such as molybdenum oxide, titanium oxide, vanadium oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide , tantalum oxide, silver oxide, tungsten oxide or manganese oxide, etc., or p-type dopants and hole transport material dopants that can use strong electron withdrawing systems, such as hexacyanohexaazatriphenylene group, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane (F4-TCNQ), or 1,2,3-tri[(cyano)( 4-cyano-2,3,5,6-tetrafluorophenyl)methylene]cyclopropane, etc.
  • inorganic oxides such as molybdenum oxide, titanium oxide, vanadium oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium
  • the thickness of the hole injection layer may be about 5 nm to 20 nm.
  • the hole transport layer and the electron blocking layer may adopt aromatic amine or carbazole materials with higher hole mobility, such as 4,4'-bis[N-(1-naphthyl)-N -Phenylamino]biphenyl (NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'- Diamine (TPD), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (BAFLP), 4,4'-bis[N-(9,9-dimethyl Fluoren-2-yl)-N-phenylamino]biphenyl (DFLDPBi), 4,4'-bis(9-carbazolyl)biphenyl (CBP) or 9-phenyl-3-[4-(10 - Phenyl-9-anthryl)phenyl]-9H-carbazole (PCz) 4,4'-
  • the thickness of the hole transport layer may be about 100 nm to 150 nm, and the thickness of the electron blocking layer may be about 5 nm to 20 nm, so as to adjust the length of the microcavity and improve the light extraction performance of the light emitting device.
  • the material of the light-emitting layer can be an organic small molecule material or a quantum dot material, etc., including but not limited to oxadiazole and its derivatives, triazole and its derivatives, rhodamine and its derivatives , 1,8-naphthalimide derivatives, pyrazoline derivatives, triphenylamine derivatives, CdSe/ZnS, PbS quantum dots, etc.
  • the light-emitting layer material may contain one material, or may contain two or more mixed materials.
  • Light-emitting materials are classified into blue light-emitting materials, green light-emitting materials, and red light-emitting materials.
  • the blue light-emitting material can be selected from pyrene derivatives, anthracene derivatives, fluorene derivatives, perylene derivatives, styrylamine derivatives, metal complexes, and the like.
  • ADN 9,10-bis-(2-naphthyl)anthracene
  • the green light-emitting material can be selected from, for example, coumarin dyes, copper quinacridine derivatives, polycyclic aromatic hydrocarbons, diamineanthracene derivatives, carbazole derivatives or metal complexes and the like.
  • coumarin 6 C-6
  • coumarin 545T C-525T
  • copper quinacridone Q
  • N,N'-dimethylquinacridone DMQA
  • N10,N10'-diphenyl-N10,N10'-diphthaloyl-9,9'-dianthracene-10,10'-diamine BA-NPB for short
  • tris (8-hydroxyquinoline) aluminum (III) referred to as Alq3
  • tris (2-phenylpyridine) iridium Ir(ppy)3
  • the red light-emitting material can be selected from, for example, DCM series materials or metal complexes.
  • DCM 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran
  • DCJTB 4-(dicyanomethyl)- 2-tert-Butyl-6-(1,1,7,7-tetramethyljulonidine-9-enyl)-4H-pyran
  • PtOEP platinum octaethylporphyrin
  • PtOEP bis(2-(2'-benzothienyl)pyridine-N,C3')( Acetylacetone) iridium
  • the light-emitting layer including two or more kinds of mixed materials may include a host material and a guest material, and the doping ratio of the guest material is 1% to 20%. Within this doping ratio range, the host material can effectively transfer the exciton energy to the guest material to excite the guest material to emit light. The host material "dilutes" the guest material, which can effectively improve the intermolecular collision of the guest material and the energy difference. Fluorescence quenching caused by mutual collision improves luminous efficiency and device lifetime.
  • the doping ratio refers to the ratio of the mass of the guest material to the mass of the light-emitting layer, that is, the mass percentage.
  • the host material and the guest material can be co-evaporated through a multi-source evaporation process, so that the host material and the guest material are uniformly dispersed in the light-emitting layer, and the evaporation rate of the guest material can be controlled during the evaporation process. to control the doping ratio, or to control the doping ratio by controlling the evaporation rate ratio of the host material and the guest material.
  • the thickness of the light emitting layer 50 may be about 10 nm to 25 nm.
  • the hole blocking layer may adopt an aromatic heterocyclic compound, such as benzimidazole derivatives, imidazopyridine derivatives, benzimidazophenanthridine derivatives and other imidazole derivatives; Azine derivatives such as azine derivatives; quinoline derivatives, isoquinoline derivatives, phenanthroline derivatives and other compounds containing a nitrogen-containing six-membered ring structure (including compounds having a phosphine oxide-based substituent on a heterocyclic ring) )Wait.
  • aromatic heterocyclic compound such as benzimidazole derivatives, imidazopyridine derivatives, benzimidazophenanthridine derivatives and other imidazole derivatives
  • Azine derivatives such as azine derivatives
  • quinoline derivatives isoquinoline derivatives, phenanthroline derivatives and other compounds containing a nitrogen-containing six-membered ring structure (including compounds having a phosphine oxide-based substituent on a hetero
  • the thickness of the hole blocking layer may be about 5 nm to 15 nm.
  • the electron injection layer may adopt alkali metals or metals, such as materials such as lithium fluoride (LiF), ytterbium (Yb), magnesium (Mg), or calcium (Ca), or compounds of these alkali metals or metals Wait.
  • alkali metals or metals such as materials such as lithium fluoride (LiF), ytterbium (Yb), magnesium (Mg), or calcium (Ca), or compounds of these alkali metals or metals Wait.
  • the electron injection layer may have a thickness of about 0.5 nm to 2 nm.
  • the thickness of the organic light-emitting layer between the cathode and the anode can be designed to meet the optical path requirements of the optical micro-resonator, so as to obtain optimal light intensity and color.
  • the organic electroluminescence device can be applied to a display substrate using an OLED as a light-emitting device and controlled by a thin film transistor (Thin Film Transistor, TFT for short).
  • a display substrate including an OLED may be prepared by the following preparation method.
  • a driving circuit layer is formed on a substrate through a patterning process, and the driving circuit layer of each sub-pixel may include a driving transistor and a storage capacitor constituting a pixel driving circuit.
  • a flat layer is formed on the substrate on which the aforementioned structure is formed, and a via hole exposing the drain electrode of the driving transistor is formed on the flat layer of each sub-pixel.
  • an anode is formed through a patterning process, and the anode of each sub-pixel is connected to the drain electrode of the driving transistor through a via hole on the flat layer.
  • a pixel definition layer is formed through a patterning process, and a pixel opening exposing the anode is formed on the pixel definition layer of each sub-pixel, and each pixel opening serves as a light-emitting area of each sub-pixel.
  • the hole injection layer and the hole transport layer are sequentially evaporated by using an open mask, and the hole injection layer and the hole transport layer are formed on the organic electroluminescent device.
  • a common layer of layers that is, the hole injection layers of all sub-pixels are connected, and the hole transport layers of all sub-pixels are connected.
  • the area of each of the hole injection layer and the hole transport layer is approximately the same, and the thicknesses thereof are different.
  • the electron blocking layer and the red light-emitting layer, the electron blocking layer and the green light-emitting layer, and the electron blocking layer and the blue light-emitting layer were respectively evaporated on different sub-pixels by using a fine metal mask (Fine Metal Mask, FMM for short).
  • FMM Fine Metal Mask
  • the electron blocking layer and the light-emitting layer of adjacent sub-pixels may have a small amount of overlap (for example, the overlapping portion occupies less than 10% of the area of the respective light-emitting layer patterns), or may be isolated.
  • the hole blocking layer, the electron transport layer, the electron injection layer and the cathode are sequentially evaporated by using an open mask to form the common hole blocking layer, the electron transport layer, the electron injection layer and the cathode on the organic electroluminescent device.
  • layer that is, the hole blocking layers of all sub-pixels are connected, the electron transport layers of all sub-pixels are connected, the electron injection layers of all sub-pixels are connected, and the cathodes of all sub-pixels are connected.
  • the orthographic projection of the electron transport layer on the substrate includes the orthographic projection of the light-emitting layer on the substrate, and the orthographic projection of the electron transport layer on the substrate The area is larger than that of the light-emitting layer.
  • the orthographic projection of the electron transport layer on the substrate at least includes the orthographic projection of the light-emitting regions of the two sub-pixels on the substrate.
  • the orthographic projection of one or more of the hole injection layer, hole transport layer, hole blocking layer, electron transport layer, electron injection layer, and cathode on the substrate is continuous.
  • at least one of the hole injection layer, the hole transport layer, the hole blocking layer, the electron transport layer, the electron injection layer, and the cathode of at least one row or column of subpixels is connected.
  • at least one of the hole injection layer, the hole transport layer, the hole blocking layer, the electron transport layer, the electron injection layer, and the cathode of the plurality of subpixels is connected.
  • the organic light emitting layer may include a microcavity adjustment layer between the hole transport layer and the light emitting layer.
  • a fine metal mask can be used to vapor-deposit a red microcavity adjusting layer and a red light-emitting layer, a green microcavity adjusting layer and a green light-emitting layer, and a blue microcavity adjusting layer on different sub-pixels, respectively. layer and blue light-emitting layer.
  • the red microcavity adjusting layer, the green microcavity adjusting layer, and the blue microcavity adjusting layer may include electron blocking layers.
  • the orthographic projection of the light-emitting layer of at least part of the sub-pixels on the substrate overlaps with the orthographic projection of the pixel driving circuit driving on the substrate.
  • the vapor deposition of the electron transport layer may adopt a multi-source co-evaporation method to form an electron transport layer including a first host material and a second host material.
  • the mixing ratio is regulated by the evaporation rate and the evaporation rate of the second host material.
  • the mass percentage of the first host material in the electron transport layer is 60% to 80%, and the mass percentage of the second host material in the electron transport layer is 20% to 20%. 40%.
  • the mass percentage of the first host material in the electron transport layer is 70%, and the mass percentage of the second host material in the electron transport layer is 30%.
  • the mass percentage of the first host material in the electron transport layer is 0 to 10%, and the mass percentage of the second host material in the electron transport layer is 90% to 100%.
  • the mass percentage of the second host material in the electron transport layer is 100%.
  • the electron transport layer may be evaporated in the following manner: during the process from the start of the evaporation to the end of the evaporation, the evaporation rate of the first host material gradually decreases, and the evaporation rate of the second host material gradually increases . For example, at the start of evaporation, the evaporation rate of the first host material is Then the evaporation rate gradually decreased.
  • the evaporation rate was At the beginning of evaporation, the evaporation rate of the second host material is Then the evaporation rate gradually increased, and at the end of the evaporation, the evaporation rate was In this way, on the side close to the light-emitting layer, the mass percentage of the first host material in the electron transport layer is about 60%, and the mass percentage of the second host material is about 40%; on the side away from the light-emitting layer, the first host material in the electron transport layer is about 40% by mass. The mass percentage of the material is about 10%, and the mass percentage of the second host material is about 90%.
  • the mass percentage of the first host material in the electron transport layer is about 80%, and the mass percentage of the second host material is about 20%; on the side away from the light-emitting layer, the first host material in the electron transport layer is about 20% by mass.
  • the mass percentage of the material is about 0, and the mass percentage of the second host material is about 100%.
  • the decreasing manner and decreasing degree of the vapor deposition rate of the first host material, and the increasing manner and increasing degree of the vapor deposition rate of the second host material can be set according to actual conditions, such as continuous decreasing or continuous Increment, or adopt step decrease or step increase, which is not limited in the present disclosure.
  • Table 1 shows the refractive indices of electron transport layers with different mixing ratios at a wavelength of 460 nm.
  • the electron transport layer only contains the second host material (the ratio of the first host material to the second host material is about 0%: 100%)
  • the refractive index of the electron transport layer is low, only 1.65
  • the refractive index of the electron transport layer can be increased.
  • the mass percentage of the first host material increases, the refractive index of the electron transport layer gradually increases.
  • the electron transport layer has a The refractive index can reach 1.95, and the refractive index of the electron transport layer is increased by about 18%.
  • the refractive index of the first host material is about 2.05.
  • Table 1 Refractive index of electron transport layers with different mixing ratios at wavelength 460 nm
  • Second Body Material Refractive index (wavelength 460nm)
  • Table 2 shows the refractive indices of the electron transport layers with different mixing ratios at a wavelength of 530 nm.
  • Table 2 shows the refractive indices of the electron transport layers with different mixing ratios at a wavelength of 530 nm.
  • the refractive index of the electron transport layer is low, only about 1.62.
  • the refraction of the electron transport layer can be increased. Rate.
  • the refractive index of the electron transport layer gradually increases.
  • the ratio of the first host material to the second host material in the electron transport layer is about 70%: 30%
  • the electron transport layer has a The refractive index can reach 1.91, and the refractive index of the electron transport layer is increased by about 18%.
  • the refractive index of the first host material is about 2.0.
  • Second Body Material Refractive index (wavelength 530nm) 0%: 100% 1.62 30%: 70% 1.75 50%:50% 1.84 70%: 30% 1.91
  • Table 3 shows the refractive indices of the electron transport layers with different mixing ratios at a wavelength of 620 nm.
  • the refractive index of the electron transport layer is low, only about 1.60.
  • the refraction of the electron transport layer can be increased Rate.
  • the refractive index of the electron transport layer gradually increases.
  • the ratio of the first host material to the second host material in the electron transport layer is about 70%: 30%, the electron transport layer has a The refractive index can reach 1.86, and the refractive index of the electron transport layer is increased by about 16%.
  • the refractive index of the first host material is about 1.96.
  • the evaporation rate of the first host material may be set to 70% E MAX
  • the evaporation rate of the second host material may be set to 30% E MAX when the electron transport layer starts to be evaporated.
  • the ratio of the first host material to the second host material in the plated electron transport layer is about 70%:30%, so that the side of the electron transport layer close to the light-emitting layer has a higher refractive index. Subsequently, the evaporation rate of the first host material can be gradually decreased, and the evaporation rate of the second host material can be gradually increased.
  • the evaporation rate of the first host material becomes 0, and the second host material
  • the evaporation rate becomes E MAX
  • the ratio of the first host material to the second host material in the vapor-deposited electron transport layer is about 0%:100%, so that the electron transport layer on the side close to the cathode has a lower refractive index.
  • the display substrate may include red sub-pixels emitting red light, green sub-pixels emitting green light, and blue sub-pixels emitting blue light. Since the electron transport layer is a common layer, the electron transport layer has different refractive indices in the regions where the red sub-pixel, the green sub-pixel and the blue sub-pixel are located.
  • the electron transport layer has a maximum refractive index n RMAX for red light in a wavelength range of 600 nm to 640 nm, a maximum refractive index for green light n GMAX in a wavelength range of 510 nm to 550 nm, and a wavelength range of 440 nm to 480 nm.
  • Maximum blue refractive index n BMAX may satisfy:
  • the electron transport layer has a minimum refractive index n RMIN for red light in a wavelength range of 600 nm to 640 nm, a minimum refractive index for green light n GMIN in a wavelength range of 510 nm to 550 nm, and a minimum refractive index for green light in the wavelength range of 440 nm to 480 nm.
  • Minimum blue refractive index n BMIN may satisfy:
  • the position of the maximum refractive index in the electron transport layer is on the side of the electron transport layer close to the light emitting layer, and the position of the minimum refractive index in the electron transport layer is on the side of the electron transport layer away from the light emitting layer.
  • the difference in the refractive index of the electron transport layer in the range where the red sub-pixel, the green sub-pixel and the blue sub-pixel are located is small, and under the same thickness , the difference between the effect of the electron transport layer on the microcavity effect is small, and the effect of the electron transport layer on the red light extraction efficiency, green light extraction efficiency and blue light extraction efficiency can be relatively balanced, and the three colors of red light, green light and blue light can be optimized at the same time, Maximize the overall light output efficiency and light quality.
  • Tables 4 and 5 are the results of the comparative experiments.
  • the organic light-emitting layers of Comparative Structure 1 to Comparative Structure 3 are all HIL/HTL/EBL/EML/HBL/ETL/EIL
  • the hole injection layer HIL, hole transport layer HTL, and electron blocking layer in the above structures are The materials and thicknesses of the EBL, the light-emitting layer EML, the hole blocking layer HBL, and the hole injection layer EIL are all the same, and the thickness of the electron transport layer ETL in the above structure is all the same.
  • Table 4 is the mixing of electron transport layers in each comparative structure of the disclosed exemplary embodiment.
  • the proportion of the second host material in the electron transport layer is 100%, and along the direction from the light-emitting layer to the cathode, the refractive index in the electron transport layer is different changing.
  • the proportion of the first host material in the electron transport layer is 30%, and the proportion of the second host material in the electron transport layer is 70%; On the side away from the light-emitting layer, the proportion of the second host material in the electron transport layer is 100%.
  • the proportion of the first host material in the electron transport layer is 70%, and the proportion of the second host material in the electron transport layer is 30%; On the side away from the light-emitting layer, the proportion of the second host material in the electron transport layer is 100%.
  • Table 5 is the comparison result of the light extraction efficiency of the comparative structure of the exemplary embodiment of the present disclosure
  • FIG. 8 is the comparison result of the light extraction efficiency of the comparative structure of the exemplary embodiment of the present disclosure, wherein the abscissa is the mixing ratio of the two materials, and the ordinate is the light extraction efficiency .
  • Contrast structure 1 15.80% Contrast structure 2 16.90% Contrast structure 3 18.20%
  • FIGS. 9a to 9c are diagrams of mode ratio distributions of light emitting devices according to exemplary embodiments of the present disclosure. According to Maxwell's equation and boundary conditions, 100% of the total light-emitting energy of the light-emitting device can be decomposed into different forms of energy mode distribution.
  • OLED light-emitting devices can contain four energy mode distributions, namely: SPP mode, waveguide mode, absorption mode and out-coupling mode, of which only the out-coupling mode can improve the efficiency of the light-emitting device.
  • Fig. 9a is the mode proportion distribution diagram of the comparative structure 1 (stacked average contribution)
  • Fig. 9b is the mode proportion distribution diagram of the comparative structure 2
  • Fig. 9c is the mode proportion distribution diagram of the comparative structure 3
  • the proportion of each mode is from the top
  • SPP mode waveguide mode
  • absorption mode absorption mode
  • out-coupled light mode the proportion of each mode is from the top
  • the comparison The refractive index of the electron transport layer near the light-emitting layer in structure 3 is greater than the refractive index of the electron transport layer near the light-emitting layer in comparative structure 2, which further improves the film reflection effect between the electron transport layer and the light-emitting layer, making the comparison
  • the proportion of the SPP loss mode increases, and the proportion of the waveguide mode decreases, but the decrease in the proportion of the waveguide mode is greater than the increase in the proportion of the SPP loss mode, so the proportion of the coupled out light mode in the comparison structure 3 increases, and further
  • the exemplary embodiment of the present disclosure adopts a mixed structure of a first host material and a second host material through the electron transport layer, and the refractive index of the electron transport layer on the side close to the light-emitting layer is greater than the refractive index of the electron transport layer on the side away from the light-emitting layer, and the maximum
  • the combination of refractive indices in the multi-film system is made more reasonable to the limit, the optical performance of the light-emitting device is optimized, the coupling and outgoing efficiency of the light-emitting device is effectively improved, and other undesired mode effects are correspondingly suppressed, which is more conducive to the use of the device.
  • the present disclosure also provides a method for preparing an organic electroluminescent device, comprising:
  • An electron transport layer is formed, the electron transport layer includes a first host material and a second host material, and the mixing ratio of the first host material and the second host material on the side close to the light-emitting layer in the electron transport layer is different from that of the the mixing ratio of the first host material and the second host material on the side away from the light-emitting layer in the electron transport layer;
  • forming the electron transport layer includes: using a co-evaporation method of a first host material source and a second host material source, and during the process from the start of the evaporation to the end of the evaporation, controlling the amount of the first host material.
  • the evaporation rate is gradually decreased, and the evaporation rate of the second host material is gradually increased, so that the mass percentage of the first host material in the electron transport layer is gradually increased along the direction from being close to the light-emitting layer to being away from the light-emitting layer. Decrease, the mass percentage of the second host material in the electron transport layer gradually increases.
  • the evaporation rate of the first host material is controlled to be to The evaporation rate of the second host material is controlled to be to At the end of the evaporation, the evaporation rate of the first host material is controlled to be 0 to The evaporation rate of the second host material is controlled to be to so that on the side close to the light-emitting layer, the mass percentage of the first host material in the electron transport layer is 60% to 80%, and the mass percentage of the second host material in the electron transport layer is 20% to 40%; on the side away from the light-emitting layer , the mass percentage of the first host material in the electron transport layer is about 0 to 10%, and the mass percentage of the second host material in the electron transport layer is about 90% to 100%.
  • the present disclosure also provides a display device including the aforementioned organic electroluminescence device.
  • the display device can be any product or component with a display function, such as a mobile phone, a tablet computer, a TV, a monitor, a notebook computer, a digital photo frame, a navigator, a car monitor, a smart watch, a smart bracelet, and the like.

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Abstract

一种有机电致发光器件及其制备方法、显示装置。有机电致发光器件包括阳极、阴极以及设置在所述阳极和阴极之间的发光层和电子传输层，所述电子传输层设置在所述发光层与阴极之间；所述电子传输层包括第一主体材料和第二主体材料，所述电子传输层中靠近所述发光层一侧的第一主体材料和第二主体材料的混合比例不同于所述电子传输层中远离所述发光层一侧的第一主体材料和第二主体材料的混合比例。

Description

有机电致发光器件及其制备方法、显示装置 技术领域
本公开涉及但不限于显示技术领域，尤指一种有机电致发光器件及其制备方法、显示装置。
背景技术
有机电致发光器件(Organic Light Emitting Device，简称OLED)为主动发光器件，具有发光、超薄、广视角、高亮度、高对比度、较低耗电、极高反应速度等优点，已逐渐成为极具发展前景的下一代显示技术。随着显示技术的不断发展，以OLED为发光器件、由薄膜晶体管(Thin Film Transistor，简称TFT)进行信号控制的显示装置已成为目前显示领域的主流产品。
OLED包括阳极、阴极以及设置在阳极和阴极之间的发光层，其发光原理是将空穴、电子分别由阳极、阴极注入至发光层，当电子和空穴在发光层中相遇时，电子和空穴复合从而产生激子(exciton)，在从激发态转变为基态的同时，这些激子发光。为了使电子和空穴在较低的驱动电压下顺利地从电极注入至发光层，阳极与发光层之间配置有空穴注入层和空穴传输层，阴极与发光层之间配置有电子注入层和电子传输层。为了使OLED达到更好的发光效率，电子传输层的设计是比较重要的。
发明内容
以下是对本文详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。
一方面，本公开示例性实施例提供了一种有机电致发光器件，包括阳极、阴极以及设置在所述阳极和阴极之间的发光层和电子传输层，所述电子传输层设置在所述发光层与阴极之间；所述电子传输层包括第一主体材料和第二主体材料，所述电子传输层中靠近所述发光层一侧的第一主体材料和第二主体材料的混合比例不同于所述电子传输层中远离所述发光层一侧的第一 主体材料和第二主体材料的混合比例。
在示例性实施方式中，所述第一主体材料的折射率大于所述第二主体材料的折射率。
在示例性实施方式中，沿着靠近所述发光层到远离所述发光层的方向，所述电子传输层中第一主体材料的质量百分比逐渐降低，所述电子传输层中第二主体材料的质量百分比逐渐增加。
在示例性实施方式中，在所述电子传输层靠近所述发光层一侧，所述电子传输层中第一主体材料的质量百分比为60％至80％，所述电子传输层中第二主体材料的质量百分比为20％至40％。
在示例性实施方式中，在所述电子传输层远离所述发光层一侧，所述电子传输层中第一主体材料的质量百分比为0至10％，所述电子传输层中第二主体材料的质量百分比为90％至100％。
在示例性实施方式中，所述发光层的厚度为10nm至25nm，所述电子传输层的厚度为20nm至50nm，在所述电子传输层靠近所述发光层的一侧，所述电子传输层的折射率为1.80至2.00。
在示例性实施方式中，所述电子传输层的厚度为20nm至50nm，所述阴极的厚度为10nm至20nm，在所述电子传输层靠近所述阴极的一侧，所述电子传输层的折射率为1.55至1.70。
在示例性实施方式中，所述阳极和发光层之间还设置有空穴注入层、空穴传输层和电子阻挡层，所述发光层和电子传输层之间还设置有空穴阻挡层，所述电子传输层和阴极之间还设置有电子注入层；所述空穴注入层的厚度为5nm至20nm，所述空穴传输层的厚度为100nm至150nm，所述电子阻挡层的厚度为5nm至20nm，所述发光层的厚度为10nm至25nm，所述空穴阻挡层的厚度为5nm至15nm，所述电子注入层的厚度为0.5nm至2nm；在所述电子传输层靠近所述空穴阻挡层的一侧，所述电子传输层的折射率为1.80至2.00，在所述电子传输层靠近所述电子注入层的一侧，所述电子传输层的折射率为1.55至1.70。
在示例性实施方式中，所述电子传输层在波长600nm至640nm范围内 具有最大红光折射率n RMAX，在波长510nm至550nm范围内具有最大绿光折射率n GMAX，在波长440nm至480nm范围内具有最大蓝光折射率n BMAX；所述电子传输层满足：
│n BMAX-n GMAX│≤0.4，│n BMAX-n RMAX│≤0.8。
在示例性实施方式中，所述最大红光折射率n RMAX为1.81至1.91，所述最大绿光折射率n GMAX为1.86至1.96，所述最大蓝光折射率n BMAX为1.90至2.00。
在示例性实施方式中，所述电子传输层在波长600nm至640nm范围内具有最小红光折射率n RMIN，在波长510nm至550nm范围内具有最小绿光折射率n GMIN，在波长440nm至480nm范围内具有最小蓝光折射率n BMIN；所述电子传输层满足：
│n BMIN-n GMIN│≤0.5，│n BMIN-n RMIN│≤1.0。
在示例性实施方式中，所述最小红光折射率n RMIN为1.55至1.65，所述最小绿光折射率n GMIN为1.57至1.67，所述最小蓝光折射率n BMIN为1.60至1.70。
另一方面，本公开示例性实施例还提供了一种显示装置，包括前述的有机电致发光器件。
又一方面，本公开示例性实施例还提供了一种有机电致发光器件的制备方法，包括：
形成阳极；
形成发光层；
形成电子传输层，所述电子传输层包括第一主体材料和第二主体材料，所述电子传输层中靠近所述发光层一侧的第一主体材料和第二主体材料的混合比例不同于所述电子传输层中远离所述发光层一侧的第一主体材料和第二主体材料的混合比例；
形成阴极。
在示例性实施方式中，形成电子传输层包括：采用第一主体材料源和第 二主体材料源共蒸镀方式，从蒸镀开始到蒸镀结束的过程中，控制所述第一主体材料的蒸镀速率逐渐下降，所述第二主体材料的蒸镀速率逐渐增加，使得沿着靠近所述发光层到远离所述发光层的方向，所述电子传输层中第一主体材料的质量百分比逐渐降低，所述电子传输层中第二主体材料的质量百分比逐渐增加。
在示例性实施方式中，在蒸镀开始时，控制所述第一主体材料的蒸镀速率为
Figure PCTCN2021089833-appb-000001
至
Figure PCTCN2021089833-appb-000002
控制所述第二主体材料的蒸镀速率为
Figure PCTCN2021089833-appb-000003
至
Figure PCTCN2021089833-appb-000004
在蒸镀结束时，控制所述第一主体材料的蒸镀速率为0至
Figure PCTCN2021089833-appb-000005
控制所述第二主体材料的蒸镀速率为
Figure PCTCN2021089833-appb-000006
至
Figure PCTCN2021089833-appb-000007
在阅读并理解了附图和详细描述后，可以明白其他方面。
附图说明
附图用来提供对本公开技术方案的进一步理解，并且构成说明书的一部分，与本公开的实施例一起用于解释本公开的技术方案，并不构成对本公开技术方案的限制。附图中各部件的形状和大小不反映真实比例，目的只是示意说明本公开内容。
图1为一种显示装置的结构示意图；
图2为一种显示装置的平面结构示意图；
图3为一种像素驱动电路的等效电路示意图；
图4为一种像素驱动电路的工作时序图；
图5为一种显示装置的剖面结构示意图；
图6为本公开示例性实施例一种发光器件的结构示意图；
图7为本公开示例性实施例另一种发光器件的结构示意图；
图8为本公开示例性实施例对比结构的出光效率对比结果；
图9a至图9c为本公开示例性实施例发光器件的模式占比分布图。
附图标记说明:
10—阳极；              20—空穴注入层；        30—空穴传输层；
40—电子阻挡层；        50—发光层；            60—空穴阻挡层；
70—电子传输层；        80—电子注入层；        90—阴极；
101—基底；             102—驱动电路层；       103—发光结构层。
104—封装层；           210—驱动晶体管；       211—存储电容；
301—阳极；             302—像素定义层；       303—有机发光层；
304—阴极；             401—第一封装层；       402—第二封装层；
403—第三封装层。
具体实施方式
本文中的实施方式可以以多个不同形式来实施。所属技术领域的普通技术人员可以很容易地理解一个事实，就是实现方式和内容可以在不脱离本公开的宗旨及其范围的条件下被变换为各种各样的形式。因此，本公开不应该被解释为仅限定在下面的实施方式所记载的内容中。在不冲突的情况下，本公开中的实施例及实施例中的特征可以相互任意组合。
在附图中，有时为了明确起见，可能夸大表示了构成要素的大小、层的厚度或区域。因此，本公开的任意一个实现方式并不一定限定于图中所示尺寸，附图中部件的形状和大小不反映真实比例。此外，附图示意性地示出了理想的例子，本公开的任意一个实现方式不局限于附图所示的形状或数值等。
本文中的“第一”、“第二”、“第三”等序数词是为了避免构成要素的混同而设置，而不是为了在数量方面上进行限定的。
在本文中，为了方便起见，使用“中部”、“上”、“下”、“前”、“后”、“竖直”、“水平”、“顶”、“底”、“内”、“外”等指示方位或位置关系的词句以参照附图说明构成要素的位置关系，仅是为了便于描述实施方式和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本公开的限制。构成要素的位置关系可根据描述的构成要素的方向进行适当地改变。因此，不局限于在文中说明的词句，根 据情况可以适当地更换。
在本文中，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解。例如，可以是固定连接，或可拆卸连接，或一体地连接；可以是机械连接，或电连接；可以是直接相连，或通过中间件间接相连，或两个元件内部的连通。对于本领域的普通技术人员而言，可以根据情况理解上述术语在本公开中的含义。
在本文中，晶体管是指至少包括栅电极、漏电极以及源电极这三个端子的元件。晶体管在漏电极(或称漏电极端子、漏区域或漏电极)与源电极(或称源电极端子、源区域或源电极)之间具有沟道区域，并且电流能够流过漏电极、沟道区域以及源电极。在本文中，沟道区域是指电流主要流过的区域。
在本文中，第一极可以为漏电极、第二极可以为源电极，或者第一极可以为源电极、第二极可以为漏电极。在使用极性相反的晶体管的情况或电路工作中的电流方向变化的情况下，“源电极”及“漏电极”的功能有时可以互相调换。因此，在本文中，“源电极”和“漏电极”可以互相调换。
在本文中，“电连接”包括构成要素通过具有某种电作用的元件连接在一起的情况。“具有某种电作用的元件”只要可以进行连接的构成要素间的电信号的授受，就对其没有特别的限制。“具有某种电作用的元件”例如可以是电极或布线，或者是晶体管等开关元件，或者是电阻器、电感器或电容器等其它功能元件等。
在本文中，“平行”是指两条直线形成的角度为-10°以上且10°以下的状态，因此，也包括该角度为-5°以上且5°以下的状态。另外，“垂直”是指两条直线形成的角度为80°以上且100°以下的状态，因此，也包括85°以上且95°以下的角度的状态。
在本文中，“膜”和“层”可以相互调换。例如，有时可以将“导电层”换成为“导电膜”。与此同样，有时可以将“绝缘膜”换成为“绝缘层”。
本文中的“约”，是指不严格限定界限，允许工艺和测量误差范围内的数值。
图1为一种显示装置的结构示意图。如图1所示，OLED显示装置可以包括时序控制器、数据信号驱动器、扫描信号驱动器、发光信号驱动器和像素阵列，像素阵列可以包括多个扫描信号线(S1到Sm)、多个数据信号线(D1到Dn)、多个发光信号线(E1到Eo)和多个子像素Pxij。在示例性实施方式中，时序控制器可以将适合于数据信号驱动器的规格的灰度值和控制信号提供到数据信号驱动器，可以将适合于扫描信号驱动器的规格的时钟信号、扫描起始信号等提供到扫描信号驱动器，可以将适合于发光信号驱动器的规格的时钟信号、发射停止信号等提供到发光信号驱动器。数据信号驱动器可以利用从时序控制器接收的灰度值和控制信号来产生将提供到数据信号线D1、D2、D3、……和Dn的数据电压。例如，数据信号驱动器可以利用时钟信号对灰度值进行采样，并且以像素行为单位将与灰度值对应的数据电压施加到数据信号线D1至Dn，n可以是自然数。扫描信号驱动器可以通过从时序控制器接收时钟信号、扫描起始信号等来产生将提供到扫描信号线S1、S2、S3、……和Sm的扫描信号。例如，扫描信号驱动器可以将具有导通电平脉冲的扫描信号顺序地提供到扫描信号线S1至Sm。例如，扫描信号驱动器可以被构造为移位寄存器的形式，并且可以以在时钟信号的控制下顺序地将以导通电平脉冲形式提供的扫描起始信号传输到下一级电路的方式产生扫描信号，m可以是自然数。发光信号驱动器可以通过从时序控制器接收时钟信号、发射停止信号等来产生将提供到发光信号线E1、E2、E3、……和Eo的发射信号。例如，发光信号驱动器可以将具有截止电平脉冲的发射信号顺序地提供到发光信号线E1至Eo。例如，发光信号驱动器可以被构造为移位寄存器的形式，并且可以以在时钟信号的控制下顺序地将以截止电平脉冲形式提供的发光停止信号传输到下一级电路的方式产生发光信号，o可以是自然数。像素阵列可以包括多个子像素Pxij。每个子像素Pxij可以连接到对应的数据信号线、对应的扫描信号线和对应的发光信号线，i和j可以是自然数。子像素Pxij可以指其中晶体管连接到第i扫描信号线且连接到第j数据信号线的子像素。
图2为一种显示装置的平面结构示意图。如图2所示，在平行于显示装置的平面内，显示装置可以包括以矩阵方式排布的多个像素单元P，多个像素单元P的至少一个包括出射第一颜色光线的第一子像素P1、出射第二颜色 光线的第二子像素P2和出射第三颜色光线的第三子像素P3，第一子像素P1、第二子像素P2和第三子像素P3均包括像素驱动电路和发光器件。第一子像素P1、第二子像素P2和第三子像素P3中的像素驱动电路分别与扫描信号线、数据信号线和发光信号线连接，像素驱动电路被配置为在扫描信号线和发光信号线的控制下，接收数据信号线传输的数据电压，向所述发光器件输出相应的电流。第一子像素P1、第二子像素P2和第三子像素P3中的发光器件分别与所在子像素的像素驱动电路连接，发光器件被配置为响应所在子像素的像素驱动电路输出的电流发出相应亮度的光。
在示例性实施方式中，像素单元P中可以包括红色(R)子像素、绿色(G)子像素和蓝色(B)子像素，或者可以包括红色子像素、绿色子像素、蓝色子像素和白色子像素，本公开在此不做限定。在示例性实施方式中，像素单元中子像素的形状可以是矩形状、菱形、五边形或六边形。像素单元包括三个子像素时，三个子像素可以采用水平并列、竖直并列或品字方式排列，像素单元包括四个子像素时，四个子像素可以采用水平并列、竖直并列或正方形(Square)方式排列，本公开在此不做限定。
在示例性实施方式中，像素驱动电路可以是3T1C、4T1C、5T1C、5T2C、6T1C或7T1C结构。图3为一种像素驱动电路的等效电路示意图。如图3所示，像素驱动电路可以包括7个晶体管(第一晶体管T1到第七晶体管T7)、1个存储电容C和7个信号线(数据信号线D、第一扫描信号线S1、第二扫描信号线S2、发光信号线E、初始信号线INIT、第一电源线VDD和第二电源线VSS)。
在示例性实施方式中，存储电容C的第一端与第一电源线VDD连接，存储电容C的第二端与第二节点N2连接，即存储电容C的第二端与第三晶体管T3的控制极连接。
第一晶体管T1的控制极与第二扫描信号线S2连接，第一晶体管T1的第一极与初始信号线INIT连接，第一晶体管的第二极与第二节点N2连接。当导通电平扫描信号施加到第二扫描信号线S2时，第一晶体管T1将初始化电压传输到第三晶体管T3的控制极，以使第三晶体管T3的控制极的电荷量初始化。
第二晶体管T2的控制极与第一扫描信号线S1连接，第二晶体管T2的第一极与第二节点N2连接，第二晶体管T2的第二极与第三节点N3连接。当导通电平扫描信号施加到第一扫描信号线S1时，第二晶体管T2使第三晶体管T3的控制极与第二极连接。
第三晶体管T3的控制极与第二节点N2连接，即第三晶体管T3的控制极与存储电容C的第二端连接，第三晶体管T3的第一极与第一节点N1连接，第三晶体管T3的第二极与第三节点N3连接。第三晶体管T3可以称为驱动晶体管，第三晶体管T3根据其控制极与第一极之间的电位差来确定在第一电源线VDD与第二电源线VSS之间流动的驱动电流的量。
第四晶体管T4的控制极与第一扫描信号线S1连接，第四晶体管T4的第一极与数据信号线D连接，第四晶体管T4的第二极与第一节点N1连接。第四晶体管T4可以称为开关晶体管、扫描晶体管等，当导通电平扫描信号施加到第一扫描信号线S1时，第四晶体管T4使数据信号线D的数据电压输入到像素驱动电路。
第五晶体管T5的控制极与发光信号线E连接，第五晶体管T5的第一极与第一电源线VDD连接，第五晶体管T5的第二极与第一节点N1连接。第六晶体管T6的控制极与发光信号线E连接，第六晶体管T6的第一极与第三节点N3连接，第六晶体管T6的第二极与发光器件的第一极连接。第五晶体管T5和第六晶体管T6可以称为发光晶体管。当导通电平发光信号施加到发光信号线E时，第五晶体管T5和第六晶体管T6通过在第一电源线VDD与第二电源线VSS之间形成驱动电流路径而使发光器件发光。
第七晶体管T7的控制极与第一扫描信号线S1连接，第七晶体管T7的第一极与初始信号线INIT连接，第七晶体管T7的第二极与发光器件的第一极连接。当导通电平扫描信号施加到第一扫描信号线S1时，第七晶体管T7将初始化电压传输到发光器件的第一极，以使发光器件的第一极中累积的电荷量初始化或释放发光器件的第一极中累积的电荷量。
在示例性实施方式中，发光器件的第二极与第二电源线VSS连接，第二电源线VSS的信号为低电平信号，第一电源线VDD的信号为持续提供高电平信号。第一扫描信号线S1为本显示行像素驱动电路中的扫描信号线，第 二扫描信号线S2为上一显示行像素驱动电路中的扫描信号线，即对于第n显示行，第一扫描信号线S1为S(n)，第二扫描信号线S2为S(n-1)，本显示行的第二扫描信号线S2与上一显示行像素驱动电路中的第一扫描信号线S1为同一信号线，可以减少显示面板的信号线，实现显示面板的窄边框。
在示例性实施方式中，第一晶体管T1到第七晶体管T7可以是P型晶体管，或者可以是N型晶体管。像素驱动电路中采用相同类型的晶体管可以简化工艺流程，减少显示面板的工艺难度，提高产品的良率。在一些可能的实现方式中，第一晶体管T1到第七晶体管T7可以包括P型晶体管和N型晶体管。
在示例性实施方式中，第一扫描信号线S1、第二扫描信号线S2、发光信号线E和初始信号线INIT沿水平方向延伸，第二电源线VSS、第一电源线VDD和数据信号线D沿竖直方向延伸。
在示例性实施方式中，发光器件可以是有机电致发光二极管(OLED)，包括叠设的第一极(阳极)、有机发光层和第二极(阴极)。
图4为一种像素驱动电路的工作时序图。下面通过图3示例的像素驱动电路的工作过程说明本公开示例性实施例，图3中的像素驱动电路包括7个晶体管(第一晶体管T1到第六晶体管T7)、1个存储电容C和7个信号线(数据信号线D、第一扫描信号线S1、第二扫描信号线S2、发光信号线E、初始信号线INIT、第一电源线VDD和第二电源线VSS)，7个晶体管均为P型晶体管。
在示例性实施方式中，像素驱动电路的工作过程可以包括：
第一阶段A1，称为复位阶段，第二扫描信号线S2的信号为低电平信号，第一扫描信号线S1和发光信号线E的信号为高电平信号。第二扫描信号线S2的信号为低电平信号，使第一晶体管T1导通，初始信号线INIT的信号提供至第二节点N2，对存储电容C进行初始化，清除存储电容中原有数据电压。第一扫描信号线S1和发光信号线E的信号为高电平信号，使第二晶体管T2、第四晶体管T4、第五晶体管T5、第六晶体管T6和第七晶体管T7断 开，此阶段OLED不发光。
第二阶段A2、称为数据写入阶段或者阈值补偿阶段，第一扫描信号线S1的信号为低电平信号，第二扫描信号线S2和发光信号线E的信号为高电平信号，数据信号线D输出数据电压。此阶段由于存储电容C的第二端为低电平，因此第三晶体管T3导通。第一扫描信号线S1的信号为低电平信号使第二晶体管T2、第四晶体管T4和第七晶体管T7导通。第二晶体管T2和第四晶体管T4导通使得数据信号线D输出的数据电压经过第一节点N1、导通的第三晶体管T3、第三节点N3、导通的第二晶体管T2提供至第二节点N2，并将数据信号线D输出的数据电压与第三晶体管T3的阈值电压之差充入存储电容C，存储电容C的第二端(第二节点N2)的电压为Vd-|Vth|，Vd为数据信号线D输出的数据电压，Vth为第三晶体管T3的阈值电压。第七晶体管T7导通使得初始信号线INIT的初始电压提供至OLED的第一极，对OLED的第一极进行初始化(复位)，清空其内部的预存电压，完成初始化，确保OLED不发光。第二扫描信号线S2的信号为高电平信号，使第一晶体管T1断开。发光信号线E的信号为高电平信号，使第五晶体管T5和第六晶体管T6断开。
第三阶段A3、称为发光阶段，发光信号线E的信号为低电平信号，第一扫描信号线S1和第二扫描信号线S2的信号为高电平信号。发光信号线E的信号为低电平信号，使第五晶体管T5和第六晶体管T6导通，第一电源线VDD输出的电源电压通过导通的第五晶体管T5、第三晶体管T3和第六晶体管T6向OLED的第一极提供驱动电压，驱动OLED发光。
在像素驱动电路驱动过程中，流过第三晶体管T3(驱动晶体管)的驱动电流由其栅电极和第一极之间的电压差决定。由于第二节点N2的电压为Vdata-|Vth|，因而第三晶体管T3的驱动电流为：
I＝K*(Vgs-Vth) 2＝K*[(Vdd-Vd+|Vth|)-Vth] 2＝K*[(Vdd-Vd] 2
其中，I为流过第三晶体管T3的驱动电流，也就是驱动OLED的驱动电流，K为常数，Vgs为第三晶体管T3的栅电极和第一极之间的电压差，Vth为第三晶体管T3的阈值电压，Vd为数据信号线D输出的数据电压，Vdd为第一电源线VDD输出的电源电压。
图5为一种显示装置的剖面结构示意图，示意了OLED显示装置三个子像素的结构。如图5所示，在垂直于显示装置的平面上，显示装置可以包括设置在基底101上的驱动电路层102、设置在驱动电路层102远离基底101一侧的发光结构层103以及设置在发光结构层103远离基底101一侧的封装层104。在一些可能的实现方式中，显示装置可以包括其它膜层，如隔垫柱等，本公开在此不做限定。
在示例性实施方式中，基底可以是柔性基底，或者可以是刚性基底。柔性基底可以包括叠设的第一柔性材料层、第一无机材料层、半导体层、第二柔性材料层和第二无机材料层，第一柔性材料层和第二柔性材料层的材料可以采用聚酰亚胺(PI)、聚对苯二甲酸乙二酯(PET)或经表面处理的聚合物软膜等材料，第一无机材料层和第二无机材料层的材料可以采用氮化硅(SiNx)或氧化硅(SiOx)等，用于提高基底的抗水氧能力，半导体层的材料可以采用非晶硅(a-si)、多晶硅(p-si)或氧化物(Oxide)。
在示例性实施方式中，每个子像素的驱动电路层102可以包括构成像素驱动电路的多个晶体管和存储电容，图5中仅以一个驱动晶体管和一个存储电容为例进行示意。在一些可能的实现方式中，每个子像素的驱动电路层102可以包括：设置在基底上的第一绝缘层；设置在第一绝缘层上的有源层；覆盖有源层的第二绝缘层；设置在第二绝缘层上的栅电极和第一电容电极；覆盖栅电极和第一电容电极的第三绝缘层；设置在第三绝缘层上的第二电容电极；覆盖第二电容电极的第四绝缘层，第二绝缘层、第三绝缘层和第四绝缘层上开设有过孔，过孔暴露出有源层；设置在第四绝缘层上的源电极和漏电极，源电极和漏电极分别通过过孔与有源层连接；覆盖前述结构的平坦层，平坦层上开设有过孔，过孔暴露出漏电极。有源层、栅电极、源电极和漏电极组成晶体管210，第一电容电极和第二电容电极组成存储电容211。
在示例性实施方式中，发光结构层103包括在电场作用下使有机材料发光的发光器件，发光结构层103可以包括阳极301、像素定义层302、有机发光层303和阴极304。阳极301设置在平坦层205上，通过平坦层205上开设的过孔与驱动晶体管210的漏电极连接；像素定义层302设置在阳极301和平坦层205上，像素定义层302上设置有像素开口，像素开口暴露出 阳极301；有机发光层303至少部分设置在像素开口内，有机发光层303与阳极301连接；阴极304设置在有机发光层303上，阴极304与有机发光层303连接；有机发光层303在阳极301和阴极304驱动下出射相应颜色的光线。
在示例性实施方式中，封装层104可以包括叠设的第一封装层401、第二封装层402和第三封装层403，第一封装层401和第三封装层403可采用无机材料，第二封装层402可采用有机材料，第二封装层402设置在第一封装层401和第三封装层403之间，可以保证外界水汽无法进入发光结构层103。
在示例性实施方式中，OLED发光器件的有机发光层可以包括发光层(Emitting Layer，简称EML)，以及包括如下任意一种或多种：空穴注入层(Hole Injection Layer，简称HIL)、空穴传输层(Hole Transport Layer，简称HTL)、空穴阻挡层(Hole Block Layer，简称HBL)、电子阻挡层(Electron Block Layer，简称EBL)、电子注入层(Electron Injection Layer，简称EIL)、电子传输层(Electron Transport Layer，简称ETL)。在阳极和阴极的电压驱动下，利用有机材料的发光特性根据需要进行发光。
在示例性实施方式中，不同颜色的OLED发光器件的发光层不同。例如，红色发光器件包括红色发光层，绿色发光器件包括绿色发光层，蓝色发光器件包括蓝色发光层。为了降低工艺难度和提升良率，位于发光层一侧的空穴注入层和空穴传输层可以采用共通层，位于发光层另一侧的电子注入层和电子传输层可以采用共通层。在示例性实施方式中，空穴注入层、空穴传输层、电子注入层和电子传输层中的任意一层或多层可以通过一次工艺(一次蒸镀工艺或一次喷墨打印工艺)制作，但通过形成的膜层表面段差或者通过表面处理等手段实现隔离。例如，相邻子像素对应的空穴注入层、空穴传输层、电子注入层和电子传输层中的任意一层或多层可以是隔离的。在示例性实施方式中，有机发光层可以通过蒸镀工艺或者喷墨工艺制备形成。
由于市场要求产品的分辨率越来越高，要求独立子像素的亮度越来越高，要求产品的功耗越来越低，因而对显示装置中发光器件的出光效率和亮度提出了更高的要求。按照发光位置的不同，OLED显示装置可以分为底发射 OLED和顶发射OLED两种。虽然顶发射OLED具有改善发光效率、提高色纯度等特点，显示效果的增强作用明显，但也存在内部光波导、表面等离子体激元、非辐射耗散等损耗，降低了出光效率。一种OLED显示装置中，为了增强器件的出光效率，通常设置外部光取出结构，例如，在半透明的阴极上设置一层光输出耦合层，或者在半透明的阴极表面设置一层高折射率的电介质。
图6为本公开示例性实施例一种发光器件的结构示意图。如图6所示，发光器件为有机电致发光器件，可以包括阳极10、阴极90以及设置在阳极10和阴极90之间的有机发光层。在示例性实施方式中，有机发光层可以包括叠设的发光层(EML)50和电子传输层(ETL)70，电子传输层70设置在发光层50与阴极90之间。在示例性实施方式中，发光层50被配置为使电子和空穴发生复合而发出光线，电子传输层70被配置为实现注入电子定向有序的可控迁移。
在示例性实施方式中，电子传输层可以至少包括第一主体材料和第二主体材料，沿着发光层50到阴极90的方向，电子传输层中第一主体材料的质量百分比逐渐降低，电子传输层中第二主体材料的质量百分比逐渐增加。在示例性实施方式中，第一主体材料和第二主体材料可以满足：
N 1＞N 2；
其中，N 1为第一主体材料的折射率，N 2为第二主体材料的折射率。例如，第一主体材料的折射率N 1可以约为1.8(@460nm)，第二主体材料的折射率N 2可以约为1.6(@460nm)。
在示例性实施方式中，材料的折射率可以采用椭偏仪设备进行测量，@460nm表示在波长为460nm时测量的折射率。
在示例性实施方式中，在电子传输层靠近发光层的第一侧，电子传输层的折射率可以约为1.80至2.00。
在示例性实施方式中，在电子传输层远离发光层(靠近阴极)的第二侧，电子传输层的折射率可以约为1.55至1.70。
在示例性实施方式中，电子传输层的厚度可以约为20nm至50nm。
在示例性实施方式中，第一主体材料和第二主体材料可以包括但不限于如下材料：8-羟基喹啉铝(Alq3)、4,7-二苯基-1,10-菲罗啉(BPhen)、1,3,5-三(1-苯基-1H-苯并咪唑-2-基)苯(TPBI)。
在示例性实施方式中，第一主体材料和第二主体材料可以采用共蒸的方式，使第一主体材料和第二主体材料均匀分散在电子传输层中，可以在蒸镀过程中通过控制第一主体材料的蒸镀速率和第二主体材料的蒸镀速率来调控混合比例。例如，在蒸镀过程中，控制第一主体材料的蒸镀速率约为
Figure PCTCN2021089833-appb-000008
控制第二主体材料的蒸镀速率约为
Figure PCTCN2021089833-appb-000009
实现电子传输层中第一主体材料的质量百分比约为30％，电子传输层中第二主体材料的质量百分比约为70％。
一种OLED结构中，电子传输层的折射率通常具有固定的。当光波(电磁波)入射到金属与电介质分界面时，金属表面的自由电子发生集体振荡，电磁波与金属表面自由电子耦合而形成的一种沿着金属表面传播的近场电磁波，如果电子的振荡频率与入射光波的频率一致就会产生共振，在共振状态下电磁场的能量被有效地转变为金属表面自由电子的集体振动能，这时就形成的一种特殊的电磁模式：电磁场被局限在金属表面很小的范围内并发生增强，这种现象就被称为表面等离子激元(Surface Plasmon Polariton，简称SPP)效应，该效应会导致出射光效率降低。为了减少电子传输层与阴极之间的表面等离子激元现象，以减少光损耗，电子传输层需要采用较小折射率的材料。但较小折射率的电子传输层与发光层之间的膜层反射效应较低，降低了整体器件的微腔效应，降低了发光器件的出光效率。为了提高电子传输层与发光层之间的膜层反射效应，电子传输层需要采用较大折射率的材料。但较大折射率的电子传输层与阴极之间的表面等离子激元现象严重，光损耗增加，降低了发光器件的出光效率。本公开示例性实施例的电子传输层采用不同折射率的第一主体材料和第二主体材料混合而成，且不同位置第一主体材料和第二主体材料的混合比例不同，电子传输层中靠近发光层一侧的折射率大于电子传输层中远离发光层一侧的折射率，最大限度地使得多膜层体系中的折射率的搭配更加合理，优化了发光器件的光学性能，有效提高了发光器件内部的耦合出光效率，更利于发挥器件的出光特性。
本公开示例性实施例中，通过减少电子传输层中远离发光层一侧的折射 率，有效减少了电子传输层与阴极之间的表面等离子激元现象，减少了光损耗。通过增加电子传输层中靠近发光层一侧的折射率，有效提高了电子传输层与发光层之间的膜层反射效应，增强了整体器件的微腔效应。因此，本公开示例性实施例最大限度地使得多膜层体系中的折射率的搭配更加合理，优化了发光器件的光学性能，有效提高了发光器件内部的耦合出光效率，更利于发挥器件的出光特性。
在示例性实施方式中，发光层可以为红色发光层，或者可以为绿色发光层，或者可以为蓝色发光层。通过提高红色发光层、绿色发光层和蓝色发光层的发光效率，可较好地改善发光器件的整体性能。
图7为本公开示例性实施例另一种发光器件的结构示意图。如图7所示，发光器件为有机电致发光器件，可以包括阳极10、阴极90以及设置在阳极10和阴极90之间的有机发光层。在示例性实施方式中，有机发光层可以包括叠设的空穴注入层20、空穴传输层30、电子阻挡层40、发光层50、空穴阻挡层60、电子传输层70和电子注入层80。空穴注入层20、空穴传输层30和电子阻挡层40设置在阳极10与发光层50之间，空穴注入层20与阳极10连接，电子阻挡层40与发光层50连接，空穴传输层30设置在空穴注入层20和电子阻挡层40之间。空穴阻挡层60、电子传输层70和电子注入层80设置在发光层50与阴极90之间，空穴阻挡层60与发光层50连接，电子注入层80与阴极90连接，电子传输层70设置在电子注入层80之间。在示例性实施方式中，空穴注入层20被配置为降低从阳极注入空穴的势垒，使空穴能从阳极有效地注入到发光层50中。空穴传输层30被配置为实现注入空穴定向有序的可控迁移。电子阻挡层40被配置为对电子形成迁移势垒，阻止电子从发光层50中迁移出来。发光层50被配置为使电子和空穴发生复合而发出光线。空穴阻挡层60被配置为对空穴形成迁移势垒，阻止空穴从发光层50中迁移出来。电子传输层70被配置为实现注入电子定向有序的可控迁移。电子注入层80被配置为降低从阴极注入电子的势垒，使电子能从阴极有效地注入到发光层50。
在示例性实施方式中，电子传输层70的材料和结构与前述实施例的材料和结构相同或相类似，在电子传输层70靠近空穴阻挡层60的一侧，电子 传输层70的折射率可以约为1.80至2.00，在电子传输层70靠近电子注入层80的一侧，电子传输层70的折射率可以约为1.55至1.70。
在示例性实施方式中，阳极可以采用具有高功函数的金属或金属氧化物材料。对于底发射型，阳极可以采用透明氧化物材料，如氧化铟锡(ITO)或氧化铟锌(IZO)等，阳极的厚度可以约为80nm至200nm。对于顶发射型，阳极可以采用金属材料，如银(Ag)、金(Au)或它们的合金等，或者可以采用金属和透明氧化物的复合结构，如Ag/ITO、Ag/IZO或者ITO/Ag/ITO等，阳极中金属层的厚度可以约为80nm至100nm，阳极中透明氧化物的厚度可以约为5nm至20nm，使阳极在可见光区的平均反射率约为85％～95％，起到全反射阳极的作用。
在示例性实施方式中，对于顶发射型OLED，阴极可以采用金属材料，通过蒸镀工艺形成，金属材料可以采用镁(Mg)、银(Ag)或铝(Al)，或者采用合金材料，如Mg:Ag的合金，Mg:Ag比例约为9:1至1:9，阴极的厚度可以约为10nm至20nm，使阴极在波长530nm处的平均透过率约为50％～60％，起到半透半反的作用。对于底发射型OLED，阴极可以采用镁(Mg)、银(Ag)、铝(Al)或Mg:Ag的合金，阴极的厚度可以约大于80nm，使阴极具有良好的反射率，起到全反射阴极的作用。
在示例性实施方式中，空穴注入层可以采用无机的氧化物，如钼氧化物、钛氧化物、钒氧化物、铼氧化物、钌氧化物、铬氧化物、锆氧化物、铪氧化物、钽氧化物、银氧化物、钨氧化物或锰氧化物等，或者可以采用强吸电子体系的p型掺杂剂和空穴传输材料的掺杂物，如六氰基六氮杂三亚苯基、2,3,5,6-四氟-7,7',8,8'-四氰基对醌二甲烷(F4-TCNQ)，或者1,2,3-三[(氰基)(4-氰基-2,3,5,6-四氟苯基)亚甲基]环丙烷等。
在示例性实施方式中，空穴注入层的厚度可以约为5nm至20nm。
在示例性实施方式中，空穴传输层和电子阻挡层可以采用具有较高空穴迁移率的芳胺类或者咔唑材料，如4,4’-双[N-(1-萘基)-N-苯基氨基]联苯(NPB)、N,N’-双(3-甲基苯基)-N,N’-二苯基-[1,1’-联苯]-4,4’-二胺(TPD)、4-苯基-4’-(9-苯基芴-9-基)三苯基胺(BAFLP)、4,4’-双[N-(9,9-二甲基芴-2-基)-N-苯基氨基]联苯(DFLDPBi)、4,4’-二(9-咔唑基)联苯(CBP)或9-苯基-3-[4-(10- 苯基-9-蒽基)苯基]-9H-咔唑(PCzPA)等。
在示例性实施方式中，空穴传输层的厚度可以约为100nm至150nm，电子阻挡层的厚度可以约为5nm至20nm，起到调节微腔长度的作用，改善发光器件出光性能。
在示例性实施方式中，发光层材料可以采用有机小分子材料或量子点材料等，包括但不限于恶二唑及其衍生物类、三唑及其衍生物类、罗丹明及其衍生物类、1,8-萘酰亚胺类衍生物、吡唑啉衍生物、三苯胺类衍生物、CdSe/ZnS、PbS量子点等。
在示例性实施方式中，发光层材料可以包含一种材料，或者可以包含两种以上的混合材料。发光材料分为蓝色发光材料、绿色发光材料以及红色发光材料。蓝色发光材料可以选自芘衍生物、蒽衍生物、芴衍生物、苝衍生物、苯乙烯基胺衍生物或金属配合物等。例如，N1,N6-二([1,1'-联苯]-2-基)-N1,N6-二([1,1'-联苯]-4-基)芘-1,6-二胺、9,10-二-(2-萘基)蒽(ADN)、2-甲基-9,10-二-2-萘基蒽(MADN)、2,5,8,11-四叔丁基苝(TBPe)、4,4'-二[4-(二苯氨基)苯乙烯基]联苯(BDAV Bi)、4,4'-二[4-(二对甲苯基氨基)苯乙烯基]联苯(DPAVBi)、二(4,6-二氟苯基吡啶-C2,N)吡啶甲酰合铱(FIrpic)。
绿色发光材料可以选自如香豆素染料、喹吖啶铜类衍生物、多环芳香烃、二胺蒽类衍生物、咔唑衍生物或金属配合物等。例如，香豆素6(C-6)、香豆素545T(C-525T)、喹吖啶铜(QA)、N,N'-二甲基喹吖啶酮(DMQA)、5,12-二苯基萘并萘(DPT)、N10,N10'-二苯基-N10,N10'-二苯二甲酰-9,9'-二蒽-10,10'-二胺(简称BA-NPB)、三(8-羟基喹啉)合铝(III)(简称Alq3)、三(2-苯基吡啶)合铱(Ir(ppy)3)、乙酰丙酮酸二(2-苯基吡啶)铱(Ir(ppy)2(acac))。红色发光材料可以选自如DCM系列材料或金属配合物等。例如，4-(二氰基亚甲基)-2-甲基-6-(4-二甲基氨基苯乙烯基)-4H-吡喃(DCM)、4-(二氰基甲撑)-2-叔丁基-6-(1,1,7,7-四甲基久洛尼啶-9-烯基)-4H-吡喃(DCJTB),二(1-苯基异喹啉)(乙酰丙酮)铱(III)(Ir(piq)2(acac))、八乙基卟啉铂(简称PtOEP)、二(2-(2'-苯并噻吩基)吡啶-N,C3')(乙酰丙酮)合铱(简称Ir(btp)2(acac)等。
在示例性实施方式中，包含两种以上混合材料的发光层可以包括主体材料和客体材料，客体材料的掺杂比例为1％至20％。在该掺杂比例范围内， 主体材料可将激子能量有效转移给客体材料来激发客体材料发光，主体材料对客体材料进行了“稀释”，可以有效改善客体材料分子间相互碰撞、以及能量间相互碰撞引起的荧光淬灭，提高发光效率和器件寿命。
本公开示例性实施例中，掺杂比例是指客体材料的质量与发光层的质量之比，即质量百分比。在示例性实施方式中，可以通过多源蒸镀工艺共同蒸镀主体材料和客体材料，使主体材料和客体材料均匀分散在发光层中，可以在蒸镀过程中通过控制客体材料的蒸镀速率来调控掺杂比例，或者通过控制主体材料和客体材料的蒸镀速率比来调控掺杂比例。
在示例性实施方式中，发光层50的厚度可以约为10nm至25nm。
在示例性实施方式中，空穴阻挡层可以采用芳族杂环化合物，例如苯并咪唑衍生物、咪唑并吡啶衍生物、苯并咪唑并菲啶衍生物等咪唑衍生物；嘧啶衍生物、三嗪衍生物等嗪衍生物；喹啉衍生物、异喹啉衍生物、菲咯啉衍生物等包含含氮六元环结构的化合物(也包括在杂环上具有氧化膦系的取代基的化合物)等。例如，2-(4-联苯基)-5-(4-叔丁基苯基)-1,3,4-噁二唑(PBD)、1,3-双[5-(对叔丁基苯基)-1,3,4-噁二唑-2-基]苯(OXD-7)、3-(4-叔丁基苯基)-4-苯基-5-(4-联苯基)-1,2,4-三唑(TAZ)、3-(4-叔丁基苯基)-4-(4-乙基苯基)-5-(4-联苯基)-1,2,4-三唑(p-EtTAZ)、红菲咯啉(BPhen)、浴铜灵(BCP)或者4,4'-双(5-甲基苯并噁唑-2-基)芪(BzOs)等。
在示例性实施方式中，空穴阻挡层的厚度可以约为5nm至15nm。
在示例性实施方式中，电子注入层可以采用碱金属或者金属，例如氟化锂(LiF)、镱(Yb)、镁(Mg)或钙(Ca)等材料，或者这些碱金属或者金属的化合物等。
在示例性实施方式中，电子注入层的厚度可以约为0.5nm至2nm。
在示例性实施方式中，对于顶发射型OLED，阴极和阳极之间的有机发光层的厚度可以按照满足光学微谐振腔的光程要求设计，以获得最优的出光强度和颜色。
在示例性实施方式中，有机电致发光器件可以应用于以OLED为发光器件、由薄膜晶体管(Thin Film Transistor，简称TFT)进行信号控制的显示基 板中。在示例性实施方式中，可以采用如下制备方法制备包括OLED的显示基板。
首先，通过图案化工艺在基底上形成驱动电路层，每个子像素的驱动电路层可以包括构成像素驱动电路的驱动晶体管和存储电容。
随后，在形成前述结构的基底上形成平坦层，每个子像素的平坦层上形成有暴露出驱动晶体管的漏电极的过孔。
随后，在形成前述结构的基底上，通过图案化工艺形成阳极，每个子像素的阳极通过平坦层上的过孔与驱动晶体管的漏电极连接。
随后，在形成前述结构的基底上，通过图案化工艺形成像素定义层，每个子像素的像素定义层上形成有暴露出阳极的像素开口，每个像素开口作为每个子像素的发光区域。
随后，在形成前述结构的基底上，先采用开放式掩膜版(Open Mask)依次蒸镀空穴注入层和空穴传输层，在有机电致发光器件上形成空穴注入层和空穴传输层的共通层，即所有子像素的空穴注入层是连通的，所有子像素的空穴传输层是连通的。例如，空穴注入层和空穴传输层各自的面积大致是相同的，厚度不同。
随后，采用精细金属掩模版(Fine Metal Mask，简称FMM)在不同的子像素分别蒸镀电子阻挡层和红色发光层、电子阻挡层和绿色发光层、以及电子阻挡层和蓝色发光层，相邻子像素的电子阻挡层和发光层是可以有少量的交叠(例如，交叠部分占各自发光层图案的面积小于10％)，或者可以是隔离的。
随后，采用开放式掩膜版依次蒸镀空穴阻挡层、电子传输层、电子注入层和阴极，在有机电致发光器件上形成空穴阻挡层、电子传输层、电子注入层和阴极的共通层，即所有子像素的空穴阻挡层是连通的，所有子像素的电子传输层是连通的，所有子像素电子注入层的是连通的，所有子像素的阴极是连通的。
在示例性实施方式中，由于电子传输层是共通层，而不同子像素的发光层是隔离的，因而电子传输层在基板上的正投影包含发光层在基板上的正投 影，电子传输层的面积大于发光层的面积。
在示例性实施方式中，由于电子传输层是共通层，因而电子传输层在基板上的正投影至少包括两个子像素的发光区域在基板上的正投影。
在示例性实施方式中，空穴注入层、空穴传输层、空穴阻挡层、电子传输层、电子注入层和阴极中的一层或多层在基底上的正投影是连续的。在一些示例中，至少一行或一列的子像素的空穴注入层、空穴传输层、空穴阻挡层、电子传输层、电子注入层和阴极中的至少一层是连通的。在一些示例中，多个子像素的空穴注入层、空穴传输层、空穴阻挡层、电子传输层、电子注入层和阴极中的至少一层是连通的。
在示例性实施方式中，有机发光层可以包括位于空穴传输层和发光层之间的微腔调节层。例如，可以在形成空穴传输层之后，采用精细金属掩模版在不同的子像素分别蒸镀红色微腔调节层和红色发光层、绿色微腔调节层和绿色发光层、以及蓝色微腔调节层和蓝色发光层。在示例性实施方式中，红色微腔调节层、绿色微腔调节层和蓝色微腔调节层可以包括电子阻挡层。
在示例性实施方式中，至少部分子像素的发光层在基板上的正投影与像素驱动电路驱动在基板上的正投影有交叠。
在示例性实施方式中，蒸镀电子传输层可以采用多源共蒸镀方式，形成包含第一主体材料和第二主体材料的电子传输层，可以在蒸镀过程中通过控制第一主体材料的蒸镀速率和第二主体材料的蒸镀速率来调控混合比例。
在示例性实施方式中，在电子传输层靠近发光层一侧，电子传输层中第一主体材料的质量百分比为60％至80％，电子传输层中第二主体材料的质量百分比为20％至40％。例如，在电子传输层靠近发光层一侧，电子传输层中第一主体材料的质量百分比为70％，电子传输层中第二主体材料的质量百分比为30％。
在示例性实施方式中，在电子传输层远离所述发光层一侧，电子传输层中第一主体材料的质量百分比为0至10％，电子传输层中第二主体材料的质量百分比为90％至100％。例如，在电子传输层远离发光层一侧，电子传输层中第二主体材料的质量百分比为100％。
在示例性实施方式中，可以采用如下方式蒸镀电子传输层：从蒸镀开始到蒸镀结束的过程中，第一主体材料的蒸镀速率逐渐下降，第二主体材料的蒸镀速率逐渐增加。例如，蒸镀开始时，第一主体材料的蒸镀速率为
Figure PCTCN2021089833-appb-000010
随后蒸镀速率逐渐下降，在蒸镀结束时，蒸镀速率为
Figure PCTCN2021089833-appb-000011
蒸镀开始时，第二主体材料的蒸镀速率为
Figure PCTCN2021089833-appb-000012
随后蒸镀速率逐渐增加，在蒸镀结束时，蒸镀速率为
Figure PCTCN2021089833-appb-000013
这样，靠近发光层一侧，电子传输层中第一主体材料的质量百分比约为60％，第二主体材料的质量百分比约为40％；远离发光层一侧，电子传输层中第一主体材料的质量百分比约为10％，第二主体材料的质量百分比约为90％。又如，蒸镀开始时，第一主体材料的蒸镀速率为
Figure PCTCN2021089833-appb-000014
随后蒸镀速率逐渐下降，在蒸镀结束时，蒸镀速率为0。蒸镀开始时，第二主体材料的蒸镀速率为
Figure PCTCN2021089833-appb-000015
随后蒸镀速率逐渐增加，在蒸镀结束时，蒸镀速率为
Figure PCTCN2021089833-appb-000016
这样，靠近发光层一侧，电子传输层中第一主体材料的质量百分比约为80％，第二主体材料的质量百分比约为20％；远离发光层一侧，电子传输层中第一主体材料的质量百分比约为0，第二主体材料的质量百分比约为100％。
在示例性实施方式中，第一主体材料的蒸镀速率的递减方式和递减程度、第二主体材料的蒸镀速率的递增方式和递增程度，可以根据实际情况进行设置，如采用连续递减或连续递增，或者采用阶梯递减或阶梯递增，本公开在此不做限定。
表1为波长460nm时不同混合比例的电子传输层的折射率。如表1所示，电子传输层仅包含第二主体材料(第一主体材料与第二主体材料的占比约为0％:100％)时，电子传输层的折射率较低，仅为1.65左右，通过与高折射率的第一主体材料混合，可以增加电子传输层的折射率。随着第一主体材料质量百分比的增加，电子传输层的折射率逐渐增加，当电子传输层中第一主体材料与第二主体材料的占比约为70％:30％时，电子传输层的折射率可以达到1.95，电子传输层的折射率增加18％左右。其中，在波长460nm时，第一主体材料的折射率约为2.05左右。
表1：波长460nm时不同混合比例的电子传输层的折射率
第一主体材料：第二主体材料 折射率(波长460nm)
0％:100％ 1.65
30％:70％ 1.79
50％:50％ 1.87
70％:30％ 1.95
表2为波长530nm时不同混合比例的电子传输层的折射率。如表2所示，电子传输层仅包含第二主体材料时，电子传输层的折射率较低，仅为1.62左右，通过与高折射率的第一主体材料混合，可以增加电子传输层的折射率。随着第一主体材料质量百分比的增加，电子传输层的折射率逐渐增加，当电子传输层中第一主体材料与第二主体材料的占比约为70％:30％时，电子传输层的折射率可以达到1.91，电子传输层的折射率增加18％左右。其中，在波长530nm时，第一主体材料的折射率约为2.0左右。
表2：波长530nm时不同混合比例的电子传输层的折射率
第一主体材料：第二主体材料 折射率(波长530nm)
0％:100％ 1.62
30％:70％ 1.75
50％:50％ 1.84
70％:30％ 1.91
表3为波长620nm时不同混合比例的电子传输层的折射率。如表3所示，电子传输层仅包含第二主体材料时，电子传输层的折射率较低，仅为1.60左右，通过与高折射率的第一主体材料混合，可以增加电子传输层的折射率。随着第一主体材料质量百分比的增加，电子传输层的折射率逐渐增加，当电子传输层中第一主体材料与第二主体材料的占比约为70％:30％时，电子传输层的折射率可以达到1.86，电子传输层的折射率增加16％左右。其中，在波长620nm时，第一主体材料的折射率约为1.96左右。
表3：波长620nm时不同混合比例的电子传输层的折射率
第一主体材料：第二主体材料 折射率(波长620nm)
0％:100％ 1.60
30％:70％ 1.69
50％:50％ 1.81
70％:30％ 1.86
在示例性实施方式中，可以在开始蒸镀电子传输层时，将第一主体材料的蒸镀速率设置为70％E MAX，第二主体材料的蒸镀速率设置为30％E MAX，所蒸镀的电子传输层中第一主体材料与第二主体材料的占比约为70％:30％，使得电子传输层中靠近发光层一侧具有较高的折射率。随后，可以逐渐降低第一主体材料的蒸镀速率，逐渐增加第二主体材料的蒸镀速率，在电子传输层蒸镀完成时，第一主体材料的蒸镀速率变为0，第二主体材料的蒸镀速率变为E MAX，所蒸镀的电子传输层中第一主体材料与第二主体材料的占比约为0％:100％，使得电子传输层中靠近阴极一侧具有较低的折射率。
在示例性实施方式中，显示基板可以包括出射红色光线的红色子像素、出射绿色光线的绿色子像素和出射蓝色光线的蓝色子像素。由于电子传输层是共通层，因而电子传输层在红色子像素、绿色子像素和蓝色子像素所在区域具有不同的折射率。
在示例性实施方式中，电子传输层在波长600nm至640nm范围内具有最大红光折射率n RMAX，在波长510nm至550nm范围内具有最大绿光折射率n GMAX，在波长440nm至480nm范围内具有最大蓝光折射率n BMAX。在示例性实施方式中，电子传输层可以满足：
│n BMAX-n GMAX│≤0.4，│n BMAX-n RMAX│≤0.8。
在示例性实施方式中，电子传输层在波长600nm至640nm范围内具有最小红光折射率n RMIN，在波长510nm至550nm范围内具有最小绿光折射率n GMIN，在波长440nm至480nm范围内具有最小蓝光折射率n BMIN。在示例性实施方式中，电子传输层可以满足：
│n BMIN-n GMIN│≤0.5，│n BMIN-n RMIN│≤1.0。
在示例性实施方式中，电子传输层中最大折射率的位置是位于在电子传输层靠近发光层的一侧，电子传输层中最小折射率的位置是位于电子传输层 远离发光层的一侧。
本公开示例性实施例通过设置电子传输层不同波长下的折射率关系，使得电子传输层在红色子像素、绿色子像素和蓝色子像素所在范围内的折射率差异较小，在相同厚度下，电子传输层影响微腔效应的差异较小，电子传输层对红光出光效率、绿光出光效率和蓝光出光效率的影响可以相对平衡，可以同时优化红光、绿光和蓝光三个颜色，最大限度地提高整体的出光效率和出光品质。
表4和表5为对比实验的结果。对比实验中，对比结构1至对比结构3的有机发光层均为HIL/HTL/EBL/EML/HBL/ETL/EIL，上述结构中的空穴注入层HIL、空穴传输层HTL、电子阻挡层EBL、发光层EML、空穴阻挡层HBL和空穴注入层EIL的材料和厚度均相同，上述结构中的电子传输层ETL的厚度均相同。
表4为本公开示例性实施例各个对比结构中的电子传输层的混合情况。如表4所示，对比结构1的电子传输层中，第二主体材料在电子传输层中的占比为100％，且沿着发光层到阴极的方向，电子传输层中的折射率是不变的。对比结构2的电子传输层中，在靠近发光层的一侧，第一主体材料在电子传输层中的占比为30％，第二主体材料在电子传输层中的占比为70％；在远离发光层的一侧，第二主体材料在电子传输层中的占比为100％。对比结构3的电子传输层中，在靠近发光层的一侧，第一主体材料在电子传输层中的占比为70％，第二主体材料在电子传输层中的占比为30％；在远离发光层的一侧，第二主体材料在电子传输层中的占比为100％。
表4：对比结构中的电子传输层
Figure PCTCN2021089833-appb-000017
Figure PCTCN2021089833-appb-000018
表5为本公开示例性实施例对比结构的出光效率对比结果，图8为本公开示例性实施例对比结构的出光效率对比结果，其中横坐标为两者材料的混合比例，纵坐标为出光效率。如表5和图8所示，与对比结构1相比，由于对比结构2和对比结构3中电子传输层靠近发光层一侧混合有折射率较高的第一主体材料，折射率增加，提高了电子传输层与发光层之间的膜层反射效应，有利于发挥发光器件的出光特性，因而对比结构2和对比结构3的出光效率有所提升。与对比结构2相比，由于对比结构3中电子传输层靠近发光层一侧混合第一主体材料的比例高于对比结构2中电子传输层靠近发光层一侧混合第一主体材料的比例，对比结构3中电子传输层靠近发光层一侧的折射率大于对比结构2中电子传输层靠近发光层一侧的折射率，进一步提高了电子传输层与发光层之间的膜层反射效应，因而对比结构3的出光效率高于对比结构2的出光效率。
表5：对比结构的出光效率对比结果
  出光效率
对比结构1 15.80％
对比结构2 16.90％
对比结构3 18.20％
图9a至图9c为本公开示例性实施例发光器件的模式占比分布图。根据麦克斯韦方程和边界条件，可以将发光器件100％的总出光能量分解成不同形式的能量模式分布。通常，OLED发光器件可以包含四种能量模式分布，分别为：SPP模式，波导模式，吸收模式和耦合出光模式，其中只有耦合出光模式对发光器件效率的提升有作用，因而发光器件设计中需要通过各种光学结构来提升耦合出光模式的占比，在一定程度上抑制其它模式的占比，以达到提升发光器件效率的目的。图9a为对比结构1的模式占比分布图(stacked average contribution)，图9b为对比结构2的模式占比分布图，图 9c为对比结构3的模式占比分布图，各个模式占比从上到下分别为：SPP模式、波导模式、吸收模式和耦合出光模式，纵坐标表示平均分布占比(relative average contribution)。
如图9a至图9c所示，与对比结构1相比，由于对比结构2和对比结构3中电子传输层靠近发光层一侧混合有折射率较高的第一主体材料，折射率增加，提高了电子传输层与发光层之间的膜层反射效应，使得对比结构2和对比结构3中SPP损耗模式的占比减少，波导模式的占比增加，但SPP损耗模式占比减少的程度大于波导模式占比增加的程度，因而耦合出光模式的占比增加，提升了发光器件的效率。与对比结构2相比，由于对比结构3中电子传输层靠近发光层一侧混合第一主体材料的比例高于对比结构2中电子传输层靠近发光层一侧混合第一主体材料的比例，对比结构3中电子传输层靠近发光层一侧的折射率大于对比结构2中电子传输层靠近发光层一侧的折射率，进一步提高了电子传输层与发光层之间的膜层反射效应，使得对比结构3中SPP损耗模式的占比增加，波导模式的占比减少，但波导模式占比减少的程度大于SPP损耗模式占比增加的程度，因而对比结构3的耦合出光模式的占比增加，进一步提升了发光器件的效率。
本公开示例性实施例通过电子传输层采用第一主体材料和第二主体材料的混合结构，且电子传输层靠近发光层一侧的折射率大于电子传输层远离发光层一侧的折射率，最大限度地使得多膜层体系中的折射率的搭配更加合理，优化了发光器件的光学性能，有效提高了发光器件内部的耦合出光效率，相应抑制了其它不期望的模式效应，更利于发挥器件的出光特性。
本公开还提供了一种有机电致发光器件的制备方法，包括：
形成阳极；
形成发光层；
形成电子传输层，所述电子传输层包括第一主体材料和第二主体材料，所述电子传输层中靠近所述发光层一侧的第一主体材料和第二主体材料的混合比例不同于所述电子传输层中远离所述发光层一侧的第一主体材料和第二主体材料的混合比例；
形成阴极。
在示例性实施方式中，形成电子传输层包括：采用第一主体材料源和第二主体材料源共蒸镀方式，从蒸镀开始到蒸镀结束的过程中，控制所述第一主体材料的蒸镀速率逐渐下降，所述第二主体材料的蒸镀速率逐渐增加，使得沿着靠近所述发光层到远离所述发光层的方向，所述电子传输层中第一主体材料的质量百分比逐渐降低，所述电子传输层中第二主体材料的质量百分比逐渐增加。
在示例性实施方式中，在蒸镀开始时，控制所述第一主体材料的蒸镀速率为
Figure PCTCN2021089833-appb-000019
至
Figure PCTCN2021089833-appb-000020
控制所述第二主体材料的蒸镀速率为
Figure PCTCN2021089833-appb-000021
至
Figure PCTCN2021089833-appb-000022
在蒸镀结束时，控制所述第一主体材料的蒸镀速率为0至
Figure PCTCN2021089833-appb-000023
控制所述第二主体材料的蒸镀速率为
Figure PCTCN2021089833-appb-000024
至
Figure PCTCN2021089833-appb-000025
使得在靠近发光层一侧，电子传输层中第一主体材料的质量百分比为60％至80％，电子传输层中第二主体材料的质量百分比为20％至40％；在远离发光层一侧，电子传输层中第一主体材料的质量百分比约为0至10％，电子传输层中第二主体材料的质量百分比约为90％至100％。
本公开还提供了一种显示装置，包括前述的有机电致发光器件。显示装置可以为手机、平板电脑、电视机、显示器、笔记本电脑、数码相框、导航仪、车载显示器、智能手表、智能手环等任何具有显示功能的产品或部件。
虽然本公开所揭露的实施方式如上，但所述的内容仅为便于理解本公开而采用的实施方式，并非用以限定本公开。任何所属领域内的技术人员，在不脱离本公开所揭露的精神和范围的前提下，可以在实施的形式及细节上进行任何的修改与变化，但本申请的专利保护范围，仍须以所附的权利要求书所界定的范围为准。

Claims (16)

  1. 一种有机电致发光器件，包括阳极、阴极以及设置在所述阳极和阴极之间的发光层和电子传输层，所述电子传输层设置在所述发光层与阴极之间；所述电子传输层包括第一主体材料和第二主体材料，所述电子传输层中靠近所述发光层一侧的第一主体材料和第二主体材料的混合比例不同于所述电子传输层中远离所述发光层一侧的第一主体材料和第二主体材料的混合比例。
  2. 根据权利要求1所述的有机电致发光器件，其中，所述第一主体材料的折射率大于所述第二主体材料的折射率。
  3. 根据权利要求1所述的有机电致发光器件，其中，沿着靠近所述发光层到远离所述发光层的方向，所述电子传输层中第一主体材料的质量百分比逐渐降低，所述电子传输层中第二主体材料的质量百分比逐渐增加。
  4. 根据权利要求3所述的有机电致发光器件，其中，在所述电子传输层靠近所述发光层一侧，所述电子传输层中第一主体材料的质量百分比为60％至80％，所述电子传输层中第二主体材料的质量百分比为20％至40％。
  5. 根据权利要求3所述的有机电致发光器件，其中，在所述电子传输层远离所述发光层一侧，所述电子传输层中第一主体材料的质量百分比为0至10％，所述电子传输层中第二主体材料的质量百分比为90％至100％。
  6. 根据权利要求1所述的有机电致发光器件，其中，所述发光层的厚度为10nm至25nm，所述电子传输层的厚度为20nm至50nm，在所述电子传输层靠近所述发光层的一侧，所述电子传输层的折射率为1.80至2.00。
  7. 根据权利要求1所述的有机电致发光器件，其中，所述电子传输层的厚度为20nm至50nm，所述阴极的厚度为10nm至20nm，在所述电子传输层靠近所述阴极的一侧，所述电子传输层的折射率为1.55至1.70。
  8. 根据权利要求1所述的有机电致发光器件，其中，所述阳极和发光层之间还设置有空穴注入层、空穴传输层和电子阻挡层，所述发光层和电子传输层之间还设置有空穴阻挡层，所述电子传输层和阴极之间还设置有电子注入层；所述空穴注入层的厚度为5nm至20nm，所述空穴传输层的厚度为 100nm至150nm，所述电子阻挡层的厚度为5nm至20nm，所述发光层的厚度为10nm至25nm，所述空穴阻挡层的厚度为5nm至15nm，所述电子注入层的厚度为0.5nm至2nm；在所述电子传输层靠近所述空穴阻挡层的一侧，所述电子传输层的折射率为1.80至2.00，在所述电子传输层靠近所述电子注入层的一侧，所述电子传输层的折射率为1.55至1.70。
  9. 根据权利要求1至8任一项所述的有机电致发光器件，所述电子传输层在波长600nm至640nm范围内具有最大红光折射率n RMAX，在波长510nm至550nm范围内具有最大绿光折射率n GMAX，在波长440nm至480nm范围内具有最大蓝光折射率n BMAX；所述电子传输层满足：
    │n BMAX-n GMAX│≤0.4，│n BMAX-n RMAX│≤0.8。
  10. 根据权利要求9所述的有机电致发光器件，其中，所述最大红光折射率n RMAX为1.81至1.91，所述最大绿光折射率n GMAX为1.86至1.96，所述最大蓝光折射率n BMAX为1.90至2.00。
  11. 根据权利要求1至8任一项所述的有机电致发光器件，所述电子传输层在波长600nm至640nm范围内具有最小红光折射率n RMIN，在波长510nm至550nm范围内具有最小绿光折射率n GMIN，在波长440nm至480nm范围内具有最小蓝光折射率n BMIN；所述电子传输层满足：
    │n BMIN-n GMIN│≤0.5，│n BMIN-n RMIN│≤1.0。
  12. 根据权利要求11所述的有机电致发光器件，其中，所述最小红光折射率n RMIN为1.55至1.65，所述最小绿光折射率n GMIN为1.57至1.67，所述最小蓝光折射率n BMIN为1.60至1.70。
  13. 一种显示装置，包括权利要求1至12任一项所述的有机电致发光器件。
  14. 一种有机电致发光器件的制备方法，包括：
    形成阳极；
    形成发光层；
    形成电子传输层，所述电子传输层包括第一主体材料和第二主体材料，所述电子传输层中靠近所述发光层一侧的第一主体材料和第二主体材料的混 合比例不同于所述电子传输层中远离所述发光层一侧的第一主体材料和第二主体材料的混合比例；
    形成阴极。
  15. 根据权利要求14所述的制备方法，其中，形成电子传输层包括：采用第一主体材料源和第二主体材料源共蒸镀方式，从蒸镀开始到蒸镀结束的过程中，控制所述第一主体材料的蒸镀速率逐渐下降，所述第二主体材料的蒸镀速率逐渐增加，使得沿着靠近所述发光层到远离所述发光层的方向，所述电子传输层中第一主体材料的质量百分比逐渐降低，所述电子传输层中第二主体材料的质量百分比逐渐增加。
  16. 根据权利要求15所述的制备方法，其中，在蒸镀开始时，控制所述第一主体材料的蒸镀速率为
    Figure PCTCN2021089833-appb-100001
    至
    Figure PCTCN2021089833-appb-100002
    控制所述第二主体材料的蒸镀速率为
    Figure PCTCN2021089833-appb-100003
    至
    Figure PCTCN2021089833-appb-100004
    在蒸镀结束时，控制所述第一主体材料的蒸镀速率为0至
    Figure PCTCN2021089833-appb-100005
    控制所述第二主体材料的蒸镀速率为
    Figure PCTCN2021089833-appb-100006
    至
    Figure PCTCN2021089833-appb-100007
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