WO2021249036A1 - 发光器件及显示面板 - Google Patents

发光器件及显示面板 Download PDF

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WO2021249036A1
WO2021249036A1 PCT/CN2021/088792 CN2021088792W WO2021249036A1 WO 2021249036 A1 WO2021249036 A1 WO 2021249036A1 CN 2021088792 W CN2021088792 W CN 2021088792W WO 2021249036 A1 WO2021249036 A1 WO 2021249036A1
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light
layer
difference
emitting
absolute value
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PCT/CN2021/088792
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French (fr)
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刘孟宇
高宇
黄智�
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云谷（固安）科技有限公司
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Priority to US17/831,967 priority Critical patent/US20220302403A1/en

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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
    • H10K50/15—Hole 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
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/18—Carrier blocking layers
    • 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
    • H10K2101/30—Highest occupied molecular orbital [HOMO], lowest unoccupied molecular orbital [LUMO] or Fermi energy values
    • 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
    • H10K2101/40—Interrelation of parameters between multiple constituent active layers or sublayers, e.g. HOMO values in adjacent 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
    • H10K50/15—Hole transporting layers
    • H10K50/156—Hole transporting layers comprising a multilayered structure
    • 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]
    • H10K50/18—Carrier blocking layers
    • H10K50/181—Electron blocking layers

Definitions

  • This application belongs to the field of display technology, and specifically relates to a light-emitting device and a display panel.
  • the blue light-emitting device, the green light-emitting device, and the red light-emitting device in the OLED display panel have different lifespans, and there is a problem of white light color change when lit for a long time. For example, generally speaking, the life span of blue light-emitting devices is short, so the OLED display panel may become reddish or greenish or yellowish after long-term use.
  • the present application provides a light emitting device and a display panel to improve the life of the light emitting device by matching activation energy.
  • a technical solution adopted in this application is to provide a light emitting device, comprising: a hole transport layer, an energy level adjustment layer, and a light emitting layer arranged in a stack, the hole transport layer and the energy level There is a first difference between the average activation energy of the adjustment layer, the average activation energy of the host material in the energy level adjustment layer and the light-emitting layer has a second difference, and the absolute value of the first difference The absolute value of the second difference is greater than 0 eV.
  • Another technical solution adopted in this application is to provide a display panel including the light emitting device described in any of the above embodiments.
  • the beneficial effects of this application are: the light-emitting device provided by this application has a first non-zero difference between the average activation energy of the hole transport layer and the energy level adjustment layer, and the energy level adjustment layer and There is a non-zero second difference between the average activation energies of the host materials in the light-emitting layer.
  • the average activation energy is used to measure the energy level matching of the light-emitting device, which can improve the injection efficiency and migration efficiency of holes, extend the life of the light-emitting device, and improve the luminous efficiency of the light-emitting device.
  • FIG. 1 is a schematic structural diagram of an embodiment of a light-emitting device of this application
  • Figure 2 is a schematic diagram of the color coordinates of experimental example 1 and comparative example 1 over time;
  • FIG. 3 is a schematic structural diagram of another embodiment of the light-emitting device of the present application.
  • An electron transport layer and an energy level matching layer are added between the light emitting layer and the cathode shown in FIG. 1, and the energy level matching layer is in contact with the light emitting layer;
  • Figure 4 is a schematic diagram of the cyclic voltammetry curve of the energy level matching layer in Comparative Example 2;
  • Figure 5 is a schematic diagram of the cyclic voltammetry curve of the energy level matching layer in Experimental Example 2;
  • FIG. 6 is a schematic diagram of the luminous efficiency curve of the light-emitting device corresponding to Comparative Example 2 with temperature change;
  • FIG. 7 is a schematic diagram of a luminous efficiency curve of a light-emitting device corresponding to experimental example 2 as a function of temperature;
  • Figure 8 is a schematic diagram of the color coordinates of Comparative Example 2 and Experimental Example 2 with temperature changes;
  • FIG. 9 is a schematic structural diagram of an embodiment of a display panel of this application.
  • FIG. 1 is a schematic structural diagram of an embodiment of a light-emitting device of this application.
  • the average activation energy of the graded layer 102 has a first difference ⁇ Ea1
  • the average activation energy of the energy-level adjusted layer 102 and the light-emitting layer 104 has a second difference ⁇ Ea2.
  • the absolute value of the first difference ⁇ Ea1 is The absolute value of the value and the second difference ⁇ Ea2 is greater than 0 eV.
  • activation energy refers to the energy required for a substance to become an activated molecule. The lower the activation energy, the lower the barrier to overcome.
  • the activation energy Ea of the single substance is the average activation of the corresponding hole transport layer 100 or the energy level adjustment layer 102 or the light emitting layer 104 can.
  • the calculation process of the average activation energy of the hole transport layer 100 or the energy level adjustment layer 102 or the light emitting layer 104 corresponding to the multiple substances It can be as follows: first obtain the product value of the activation energy Ea of each substance and its corresponding molar mass fraction; and then sum the above-mentioned product values to obtain the average activation energy.
  • thermogravimetric analysis may be directly performed on the whole of the hole transport layer 100, the energy level adjustment layer 102, or the light-emitting layer 104, and the corresponding average activation energy can be directly calculated according to the result of the thermogravimetric analysis. .
  • thermogravimetric analysis refers to the method of obtaining the relationship between the mass of a substance and the temperature (or time) under the control of the program; when the thermogravimetric curve is obtained by the thermogravimetric analysis technique, the difference is subtracted and differentiated (Freeman-Carroll)
  • the average activation energy can be calculated by method or integral (OWAZa) method.
  • the highest occupied energy level orbital HOMO/lowest occupied energy level orbital LOMO is generally used to measure the energy level matching of the light emitting device 10.
  • HOMO/LOMO only considers the hole injection efficiency; however, the average activation energy is used in this application.
  • the injection efficiency and migration efficiency of holes can be considered comprehensively.
  • the life of the light-emitting device 10 can be prolonged, and the luminous efficiency of the light-emitting device 10 can be improved.
  • the aforementioned energy level adjustment layer 102 may be an electron blocking layer, and its material may be a single aromatic amine structure containing a spirofluorene group, a single aromatic amine structure containing a spiro ring unit, or the like.
  • the above-mentioned design of the energy level adjustment layer 102 can not only achieve the purpose of energy level matching, but also can block the electrons of the cathode, so as to further improve the luminous efficiency of the light-emitting device 10.
  • the material of the hole transport layer 100 may be polyparaphenylene vinylenes, polythiophenes, polysilanes, triphenylmethanes, triarylamines, hydrazones, pyrazolines, azoles, and carbazoles. Class, butadiene class, etc.
  • the absolute value of the first difference ⁇ Ea1 is greater than or equal to the absolute value of the second difference ⁇ Ea2.
  • This design method can make the number of holes concentrated at the interface between the energy level adjustment layer 102 and the light-emitting layer 104 lower than the number of holes at the interface between the hole transport layer 100 and the energy level adjustment layer 102, and avoid excessive concentration of holes The interface of the light-emitting layer 104 slows down the deterioration of the light-emitting material, thereby increasing the life of the light-emitting device 10.
  • the absolute value of the first difference ⁇ Ea1 is greater than or equal to 0.1 eV and less than or equal to 0.15 eV
  • the absolute value of the second difference ⁇ Ea2 is greater than or equal to 0.05 eV and less than Equal to 0.1eV.
  • the absolute value of the first difference ⁇ Ea1 may be 0.12 eV, 0.14 eV, etc.
  • the absolute value of the second difference ⁇ Ea2 may be 0.06 eV, 0.08 eV, etc.
  • the design of the range of the first difference ⁇ Ea1 and the second difference ⁇ Ea2 can effectively increase the life of the blue light-emitting layer, reduce the difference in life between the blue light-emitting layer and the red light-emitting layer and the green light-emitting layer, and reduce the occurrence of color shift. Probability.
  • the average activation energy of the energy level adjustment layer 102 has a difference of -0.1eV to -0.2eV (for example, -0.15eV, -0.18eV, etc.)
  • the average activation energy of the blue light-emitting layer has a difference of -0.2 eV to -0.3 eV (for example, -0.25 eV, -0.28 eV, etc.).
  • the above-mentioned design method can make the blue light-emitting device have a higher lifespan and luminous efficiency.
  • Comparative Example 1 and Experimental Example 1 were designed, in which the absolute value of the first difference ⁇ Ea1 between the average activation energy of the hole transport layer 100 and the energy level adjustment layer 102 in Experimental Example 1 is 0.1 eV, the absolute value of the second difference ⁇ Ea2 of the average activation energy of the host material in the energy level adjustment layer 102 and the blue light-emitting layer 104 is 0.05 eV.
  • the difference between Comparative Example 1 and Experimental Example 1 is that the light-emitting device does not include the energy level adjustment layer 102.
  • the performance test results of the light-emitting devices corresponding to Comparative Example 1 and Experimental Example 1 are shown in Table 1 below.
  • the BI value of Experimental Example 1 is 20% higher than that of Comparative Example 1, and the duration of Experimental Example 1 at 1200 nits brightness is 28% higher than that of Comparative Example, where BI is cd/A/CIEy, cd/A is the luminous efficiency, and CIEy is the coordinates of CIExy1931. Because the blue luminous efficiency cd/A is easily affected by the value of CIEy, the industry generally defines the blue efficiency using the BI value. It can be seen from the above performance test results that the solution adopted in this application can significantly improve the luminous efficiency and luminous life of the blue light-emitting device.
  • Figure 2 is a schematic diagram of the color coordinates of Experimental Example 1 and Comparative Example 1 over time. It can be clearly seen from FIG. 2 that compared with Comparative Example 1, the life of the blue light-emitting device increases with the passage of time, and the change of the white light color coordinate decreases with the passage of time.
  • the energy level adjustment layer 102 is doped with blue light-emitting
  • a third difference ⁇ Ea3 between the average activation energies of the materials BD, and the absolute value of the third difference ⁇ Ea3 is smaller than the absolute value of the second difference ⁇ Ea2.
  • the main role of the blue light-emitting host material BH is to transfer energy and prevent triplet energy from being overwhelmed, and the main role of the blue light-emitting doping material BD is to be responsible for light emission.
  • the blue light-emitting layer emits light
  • energy is transferred between the blue light-emitting host material BH and the blue light-emitting dopant material BD.
  • the above-mentioned average activation energy design method can make the holes transported by the energy level adjustment layer 102 more effective. Easily reach the blue light-emitting dopant material BD, the blue light-emitting host material BH can effectively transfer energy to the blue light-emitting dopant material BD, reduce the probability of energy reflow, and ensure luminous efficiency.
  • the average activation energy of the blue light-emitting host material BH has a difference of -0.2eV to -0.3eV compared to the hole transport layer 100; the average activation energy of the blue light-emitting doped material BD Compared with the hole transport layer 100, it has a difference of -0.2eV to -0.3eV.
  • the blue light-emitting host material BH can be a carbazole group derivative, an aryl silicon derivative, an aromatic derivative, a metal complex derivative, etc.
  • the blue light-emitting doping material BD can be a fluorescent doping material (for example, , Porphyrin-based compounds, coumarin-based dyes, quinacridone-based compounds, aromatic amine-based compounds, etc.) or phosphorescent dopant materials (for example, complexes containing metal iridium, etc.).
  • the absolute value of the second difference ⁇ Ea2 is greater than or equal to 0.05 eV and less than or equal to 0.1 eV
  • the absolute value of the third difference ⁇ Ea3 between the average activation energy of the energy level adjustment layer 102 and the blue light-emitting doped material BD is less than 0.05 eV, for example, the absolute value of the third difference ⁇ Ea3 may be 0.04 eV, 0.03 eV, and so on.
  • the design of the second difference ⁇ Ea2 and the third difference ⁇ Ea3 can effectively improve the luminous efficiency of the blue light-emitting layer; for example, the design of the second difference ⁇ Ea2 is beneficial to accumulate a certain number of holes and electrons. It recombines with electrons to form excitons to improve the luminous efficiency; the design of the third difference ⁇ Ea3 described above facilitates the injection of holes from the energy level adjustment layer 102 into the blue light-emitting doping material BD.
  • the absolute value of the first difference ⁇ Ea1 between the hole transport layer 100 and the energy level adjustment layer 102 is greater than or equal to 0.05 eV and less than or equal to 0.1 eV
  • the absolute value of the second difference ⁇ Ea2 between the average activation energy of the green light-emitting host material of the energy level adjustment layer 102 and the light-emitting layer 104 is greater than or equal to 0.1 eV and less than or equal to 0.15 eV.
  • the absolute value of the first difference ⁇ Ea1 may be 0.06 eV, 0.08 eV, etc.
  • the absolute value of the second difference ⁇ Ea2 may be 0.14 eV, 0.13 eV, etc.
  • the above-mentioned design method of the range of the first difference ⁇ Ea1 and the second difference ⁇ Ea2 can effectively improve the lifetime and luminous efficiency of the green light-emitting device.
  • the green light-emitting layer may also be formed of a green light-emitting host material GH and a green light-emitting doping material GD, and there is a third difference ⁇ Ea3 between the average activation energy of the energy level adjustment layer 102 and the green doping material GD,
  • the absolute value of the third difference ⁇ Ea3 is less than 0.05 eV.
  • the average activation energy of the green light-emitting host material GH has a difference of 0.15 eV to 0.2 eV compared to the hole transport layer 100, and the average activation energy of the green light-emitting doped material GD is compared with the hole transport layer 100.
  • the average activation energy of the above-mentioned energy level adjustment layer 102 is 0.05eV to 0.1eV (for example, 0.06, 0.08eV, etc.) compared with the average activation energy of the hole transport layer 100 Difference.
  • the absolute value of the first difference ⁇ Ea1 between the hole transport layer 100 and the energy level adjustment layer 102 is greater than or equal to 0.1 eV and less than or equal to 0.15 eV
  • the absolute value of the second difference ⁇ Ea2 between the average activation energy of the red light-emitting host material of the energy level adjustment layer 102 and the light-emitting layer 104 is less than 0.05 eV.
  • the absolute value of the first difference ⁇ Ea1 may be 0.12 eV, 0.14 eV, etc.
  • the absolute value of the second difference ⁇ Ea2 may be 0.04 eV, 0.03 eV, etc.
  • the above-mentioned design method of the range of the first difference ⁇ Ea1 and the second difference ⁇ Ea2 can effectively improve the lifetime and luminous efficiency of the red light-emitting device.
  • the red light-emitting layer can also be formed of a red light-emitting host material RH and a red light-emitting doped material RD, and there is a third difference ⁇ Ea3 between the average activation energy of the energy level adjustment layer 102 and the red light-emitting doped material RD.
  • the absolute value of the third difference ⁇ Ea3 is less than 0.05 eV.
  • the average activation energy of the red light-emitting host material RH has a difference of 0.20 eV to 0.25 eV compared to the hole transport layer 100, and the average activation energy of the red light-emitting doped material RD is compared with the hole transport layer 100.
  • the average activation energy of the above-mentioned energy level adjustment layer 102 is 0.10eV to 0.15eV (for example, 0.12, 0.14eV, etc.) compared to the average activation energy of the hole transport layer 100 Difference.
  • the light emitting device may further include: a first energy level layer located between the electron blocking layer and the light emitting layer 104, and the average value of the first energy level layer
  • the activation energy is between the average activation energy of the electron blocking layer and the light-emitting layer 104.
  • the second energy level layer is located between the electron blocking layer and the hole transport layer 100, and the average activation energy of the second energy level layer is between the average activation energy of the electron blocking layer and the hole transport layer 100 .
  • This design method can slow down the life loss caused by the impact of the interface between the electron blocking layer and the hole transport layer 100, and improve the life of the light-emitting device.
  • the light-emitting device 10 shown in FIG. 1 has a single-layer device structure, which may further include a cathode 108 and an anode 106. Of course, in other embodiments, it can also add an electron transport layer between the light-emitting layer 104 and the cathode 108 shown in FIG. 1.
  • FIG. 3 is a schematic structural diagram of another embodiment of a light-emitting device of the present application.
  • an electron transport layer 103a and an energy level matching layer 101a can be added between the light emitting layer 104a and the cathode 108a shown in FIG.
  • the light-emitting layer 104a is in contact.
  • the structural design of the above-mentioned light-emitting device 10a is relatively simple and easy to manufacture.
  • the highest occupied energy level orbital HOMO/lowest occupied energy level orbital LOMO is generally used to measure the energy level matching of the light-emitting device 10a.
  • HOMO/LOMO only considers the injection efficiency of electrons or holes; however, the average is used in this application.
  • the activation energy is used to measure the energy level matching of the light-emitting device 10a, which can comprehensively consider the injection efficiency and migration efficiency of holes, and further comprehensively consider the temperature, electron injection efficiency and migration efficiency, compared with the traditional HOMO/LOMO In this way, the life span of the light-emitting device 10a can be prolonged, so that the luminous efficiency of the light-emitting device 10a is improved, and the phenomenon that the luminous efficiency of the light-emitting device 10a changes greatly with temperature is reduced.
  • the probability of electrons accumulating on a specific interface can be reduced, and a higher efficiency hole/electron combination ratio can be achieved, and the hole/electron combination ratio can be improved.
  • the state that changes with current changes slows down.
  • the energy level matching layer 101a can be a hole blocking layer, and its material can be 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline BCP, 1, 3,5-Tris(N-phenyl-2-benzimidazole)benzene TPBi, Tris(8-hydroxyquinoline) aluminum(III) Alq3, 8-hydroxyquinoline-lithium Liq, bis(2-methyl) -8-Hydroxyquinoline) (4-phenylphenol) aluminum (III) BAlq, 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H -At least one of 1,2,4-triazole TAZ and the like.
  • the above-mentioned design of the energy level matching layer 101a can not only achieve the purpose of energy level matching, but also can block the holes of the anode, so as to further improve the luminous efficiency of the light emitting device 10a.
  • a material with a current change rate of less than 1% that has undergone cyclic voltammetry test can be selected; wherein, the temperature of the cyclic voltammetry test can be room temperature or higher.
  • This design method can ensure the performance stability of the energy level matching layer 101a during long-term operation and corresponding temperature, and thereby improve the problem of the luminous efficiency varying with temperature at low gray levels.
  • the light-emitting layer 104a is a blue light-emitting layer
  • the fourth difference ⁇ Ea4 between the average activation energy of the electron transport layer 103a and the energy level matching layer 101a has an absolute value of less than 0.05 eV
  • the energy level matching layer 101a The absolute value of the fifth difference ⁇ Ea5 with the average activation energy of the host material of the light-emitting layer 104 is greater than or equal to 0.1 eV and less than or equal to 0.15 eV.
  • the absolute value of the fourth difference ⁇ Ea4 may be 0.02 eV, 0.04 eV, etc.
  • the absolute value of the fifth difference ⁇ Ea5 may be 0.12 eV, 0.14 eV, etc.
  • the above-mentioned design method of the range of the fourth difference ⁇ Ea4 and the fifth difference ⁇ Ea5 can effectively improve the luminous efficiency of the blue light-emitting layer at different temperatures, and reduce the difference in luminous efficiency at different temperatures, thereby reducing the white light shift .
  • the average activation energy of the energy level matching layer 101a has a difference of -0.05eV to 0eV (for example, -0.02eV, -0.03eV, etc.) compared with the average activation energy of the electron transport layer 103a.
  • the average activation energy of the host material of the blue light-emitting layer has a difference of 0.05 eV to 0.15 eV (for example, 0.11 eV, 0.14 eV, etc.).
  • the above-mentioned design method can make the blue light-emitting device have a higher lifespan and luminous efficiency.
  • the blue light-emitting layer includes a blue light-emitting host material BH and a blue light-emitting doped material BD
  • the blue light-emitting doped material BD has a sixth difference between the average activation energy of the energy level matching layer 101a.
  • Value ⁇ Ea6 the absolute value of the sixth difference ⁇ Ea6 is smaller than the absolute value of the fifth difference ⁇ Ea5.
  • the main role of the blue light-emitting host material BH is to transfer energy and prevent triplet energy from being overwhelmed, and the main role of the blue light-emitting doping material BD is to be responsible for light emission.
  • the blue light-emitting layer When the blue light-emitting layer emits light, energy is transferred between the blue light-emitting host material BH and the blue light-emitting doping material BD.
  • the above-mentioned average activation energy design can make the electrons transmitted by the energy level matching layer 101a easier To reach the blue light-emitting dopant material BD, the blue light-emitting host material BH can effectively transfer energy to the blue light-emitting dopant material BD, reducing the probability of energy reflow and ensuring luminous efficiency.
  • the absolute value of the sixth difference ⁇ Ea6 between the blue light-emitting dopant material BD and the average activation energy of the energy level matching layer 101a is less than 0.05 eV, for example, the absolute value of the sixth difference ⁇ Ea6 may be 0.04 eV, 0.02eV and so on.
  • the difference between the average activation energy of the blue light-emitting dopant material BD and the blue light-emitting host material BH may be between 0.05 eV and 0.1 eV, for example, 0.06 eV, 0.08 eV, etc.
  • the design of the sixth difference ⁇ Ea6 and the fifth difference ⁇ Ea5 can effectively improve the luminous efficiency of the blue light-emitting layer; for example, the design of the sixth difference ⁇ Ea6 is beneficial to accumulate a certain number of holes and electrons. Recombine with electrons to form excitons to improve luminous efficiency; the design of the fifth difference ⁇ Ea5 mentioned above is beneficial to the blue light-emitting host material BH to effectively transfer energy to the blue light-emitting doping material BD, reducing the probability of energy reflow and ensuring Luminous efficiency.
  • the activation energy of each layer in Comparative Example 2 is designed as follows: the absolute value of the average activation energy difference between the blue light-emitting host material BH and the blue light-emitting doped material BD is 0.02 eV, and the blue light-emitting doped material BD The absolute value of the average activation energy difference with the energy level matching layer 101a is 0.02eV; the absolute value of the average activation energy difference between the blue light-emitting host material BH and the energy level matching layer 101a is 0.03eV, the energy level The absolute value of the average activation energy difference between the matching layer 101a and the electron transport layer 103a is 0.03 eV.
  • the blue light-emitting host material BH, the blue light-emitting dopant material BD, and the activation energy of the energy level matching layer 101a have a positive difference with respect to the electron transport layer 103a.
  • the activation energy of each layer in Experimental Example 2 is designed as follows: the absolute value of the average activation energy difference between the blue light-emitting host material BH and the blue light-emitting doped material BD is 0.1 eV, and the blue light-emitting doped material BD is related to the energy
  • the absolute value of the average activation energy difference between the level matching layers 101a is 0.04eV; the absolute value of the average activation energy difference between the blue light-emitting host material BH and the energy level matching layer 101a is 0.11eV, the energy level matching layer
  • the absolute value of the average activation energy difference between 101a and the electron transport layer 103a is 0.02 eV.
  • the activation energy of the blue light-emitting host material BH and the blue light-emitting doped material BD are both positive with respect to the electron transport layer 103a; and the activation energy of the energy level matching layer 101a With respect to the electron transport layer 103a, the difference is negative.
  • FIG. 4 is a schematic diagram of the cyclic voltammetry curve of the energy level matching layer in Comparative Example 2
  • FIG. 5 is a schematic diagram of the cyclic voltammetry curve of the energy level matching layer in Experimental Example 2. It can be seen from the figure that the current change of the energy level matching layer material of Experimental Example 2 is small after 100 cycles of cyclic voltammetry. It is found by calculation that the current change rate of the energy level matching layer material of Comparative Example 2 after 100 cycles of cyclic voltammetry is 4.4%, while the energy level matching layer material of Experimental Example 2 has experienced 100 cycles of cyclic voltammetry. The current change rate is only 0.5%.
  • FIG. 6 is a schematic diagram of the luminous efficiency curve of the light-emitting device corresponding to Comparative Example 2 with temperature change
  • FIG. 7 is a schematic diagram of the luminous efficiency curve of the light-emitting device corresponding to Experimental Example 2 with temperature change. It can be seen from the figure that the luminous efficiency change of the light-emitting device of Experimental Example 2 at various temperatures is significantly smaller than that of the light-emitting device of Comparative Example 2. In addition, the luminous efficiency of Comparative Example 2 is lower than that of Experimental Example 2. In order to achieve the same display brightness, the driving current required by Comparative Example 2 is relatively large; for example, as shown in FIG. 6 and FIG. 7, in order to achieve the same brightness, Comparative Example 2 A current density of 0.12 mA/cm 2 is required in the medium, and a current density of 0.108 mA/cm 2 is required in Experimental Example 2.
  • the luminous efficiency of the light-emitting device in Comparative Example 2 at 55°C is lower than the luminous efficiency at 25°C, and is 88.5 of the luminous efficiency at 25°C. %.
  • the luminous efficiency of the light-emitting device in Experimental Example 2 at 55° C. is increased relative to the luminous efficiency at 25° C., and is 111.6% of the luminous efficiency at 25° C.
  • FIG. 8 is a schematic diagram of the color coordinates of Comparative Example 2 and Experimental Example 2 as a function of temperature. It can be seen from the figure that, compared to Comparative Example 2, the white light of Experimental Example 2 has a smaller deviation with temperature.
  • the foregoing embodiments mainly focus on the case where the light-emitting layer 104a is a blue light-emitting layer.
  • the above method is also applicable to light-emitting layers of other colors.
  • the absolute value of the fourth difference between the average activation energy of the energy level matching layer 101a and the electron transport layer 103a is less than 0.05 eV
  • the green light emitting host material GH and the energy level matching layer The absolute value of the fifth difference between the average activation energy of 101a is less than 0.05 eV
  • the absolute value of the difference between the average activation energy of the green light-emitting host material GH and the green light-emitting doping material GD is between 0.05 eV and 0.1 eV
  • the absolute value of the sixth difference of the average activation energy between the green light-emitting doping material GD and the energy level matching layer 101a is less than 0.1 eV.
  • the energy level matching layer 101a has a difference in average activation energy greater than 0 and less than 0.05 eV relative to the electron transport layer 103a; the green light-emitting host material has a difference relative to the electron transport layer 103a The difference in average activation energy is greater than -0.05 eV and less than 0 eV; the green light-emitting dopant material has a difference in activation energy greater than or equal to -0.1 eV and less than or equal to -0.05 eV relative to the green light emitting host material.
  • the absolute value of the fourth difference between the average activation energy of the energy level matching layer 101a and the electron transport layer 103a is less than 0.05 eV
  • the red light-emitting host material of the red light-emitting layer is The absolute value of the fifth difference between the average activation energy of the energy level matching layer 101a is less than 0.05 eV
  • the absolute value of the difference between the average activation energy of the red light-emitting host material RH and the red light-emitting doped material RD is 0.08 eV
  • the absolute value of the sixth difference of the average activation energy between the red light-emitting doped material RD and the energy level matching layer 101a is between 0.08 eV and 0.12 eV.
  • the energy level matching layer 101a has a difference in average activation energy greater than 0 and less than 0.05 eV relative to the electron transport layer 103a; the red luminescent host material has a difference relative to the electron transport layer 103a The difference in average activation energy is greater than 0 to 0.05 eV; the red light-emitting dopant material has a difference in activation energy greater than or equal to -0.1 eV and less than or equal to 0 eV relative to the red light emitting host material.
  • the light emitting device provided by the present application may further include: a third energy level layer located between the hole blocking layer and the light emitting layer 104a, and the third energy level layer The average activation energy of is between the average activation energy of the hole blocking layer and the light-emitting layer 104a.
  • This design method can reduce the life loss caused by the impact of the interface between the hole blocking layer and the light emitting layer 104a, and improve the life of the light emitting device.
  • the fourth level layer is located between the hole blocking layer and the electron transport layer 103a, and the average activation energy of the fourth level layer is between the average activation energy of the hole blocking layer and the electron transport layer 103a .
  • This design method can slow down the life loss caused by the impact of the interface between the hole blocking layer and the electron transport layer 103a, and improve the life of the light-emitting device.
  • FIG. 9 is a schematic structural diagram of an embodiment of a display panel of the present application.
  • the display panel 20 provided in the present application may include the light-emitting device mentioned in any of the above-mentioned embodiments.
  • the display panel 20 may include an array substrate 200, a light-emitting layer 202, an encapsulation layer 204, etc., which are stacked and arranged.
  • the light-emitting layer 202 may include the light-emitting device mentioned in any of the foregoing embodiments, and the light-emitting device may be a blue light-emitting device, a red light-emitting device, or a green light-emitting device.
  • the hole transport layers of the blue light-emitting devices, red light-emitting devices and green light-emitting devices may be formed of the same material.
  • the energy level adjustment layer can choose different materials according to the designed activation energy requirements. This design method can reduce the difficulty of process preparation.
  • the hole transport layers of the blue light-emitting device, the red light-emitting device, and the green light-emitting device may also be formed of different materials, which is not limited in this application.

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Abstract

本申请公开了一种发光器件及显示面板，所述发光器件包括：层叠设置的空穴传输层、能级调配层和发光层，所述空穴传输层与所述能级调配层的平均活化能之间具有第一差值，所述能级调配层与所述发光层的主体材料的平均活化能之间具有第二差值，所述第一差值的绝对值和所述第二差值的绝对值大于0eV。

Description

发光器件及显示面板 技术领域
本申请属于显示技术领域，具体涉及一种发光器件及显示面板。
背景技术
OLED显示面板中的蓝色发光器件、绿色发光器件和红色发光器件的寿命不一致，在长时间点亮时存在白光颜色变化的问题。例如，一般而言，蓝色发光器件的寿命偏短，因此OLED显示面板长时间使用后存在偏红色或绿色或黄色的情况。
为了解决该问题，目前通常使用的方法包括：调整蓝色发光器件、绿色发光器件和红色发光器件的开口面积，将三者的寿命水平差异缩小。然而，从工艺角度考虑，蓝色发光器件、绿色发光器件和红色发光器件的开口面积比例无法无限制的扩大或缩小。因此，需要寻找另一种方式来改善发光器件的寿命。
申请内容
本申请提供了一种发光器件和显示面板，以通过活化能匹配的方式改善发光器件的寿命。
为解决上述技术问题，本申请采用的一个技术方案是：提供一种发光器件，包括：层叠设置的空穴传输层、能级调配层和发光层，所述空穴传输层与所述能级调配层的平均活化能之间具有第一差值，所述能级调配层与所述发光层中的主体材料的平均活化能之间具有第二差值，所述第一差值的绝对值和所述第二差值的绝对值大于0eV。
为解决上述技术问题，本申请采用的另一个技术方案是：提供一种显示面板，包括上述任一实施例中所述的发光器件。
区别于现有技术情况，本申请的有益效果是：本申请所提供的发光器件中空穴传输层与能级调配层的平均活化能之间具有非零的第一差值，能级调配层与发光层中的主体材料的平均活化能之间具有非零的第二差值。本申请中利用平均活化能来衡量发光器件中能级匹配情况，能够提高空穴的注入效率和迁移效率，延长发光器件的寿命，使得发光器件的发光效率提升。
【附图说明】
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图，其中：
图1为本申请发光器件一实施方式的结构示意图；
图2为实验例1和对比例1随时间变化的色坐标示意图；
图3为本申请发光器件另一实施方式的结构示意图，在图1中所示的发光层与阴极之间增加电子传输层和能级匹配层，且能级匹配层与发光层接触；
图4为对比例2中能级匹配层循环伏安曲线示意图；
图5为实验例2中能级匹配层循环伏安曲线示意图；
图6为对比例2对应的发光器件随温度变化的发光效率曲线示意图；
图7为实验例2对应的发光器件随温度变化的发光效率曲线示意图；
图8为对比例2和实验例2随温度变化的色坐标示意图；
图9为本申请显示面板一实施方式的结构示意图。
【具体实施方式】
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，均属于本申请保护的范围。
请参阅图1，图1为本申请发光器件一实施方式的结构示意图，该发光器件10包括层叠设置的空穴传输层100、能级调配层102和发光层104，空穴传输层100与能级调配层102的平均活化能之间具有第一差值ΔEa1，能级调配层102与发光层104中的主体材料的平均活化能之间具有第二差值ΔEa2，第一差值ΔEa1的绝对值和第二差值ΔEa2的绝对值大于0eV。
其中，活化能是指某一物质要成为活化分子所需要的能量，活化能越低表明其需要克服的势垒越低。活化能可以采用如下阿伦尼乌斯(Arrhenius)公式计算获得：Ea＝E 0+mRT，其中，Ea为活化能，E 0和m为与温度无关的常数，T为温度，R为摩尔气体常数。此外，经上述计算公式获得的活化能的单位为焦耳J，通过简单的换算公式即可将上述活化能的单位转换为电子伏特eV，其中，换算公式为：1eV＝1.602176565*10 -19J。
当空穴传输层100、能级调配层102和发光层104由单一物质形成时，单一物质的活化能Ea即为其对应的空穴传输层100或能级调配层102或发光层104的平均活化能。
当空穴传输层100、能级调配层102和发光层104由多种物质混合形成时，多种物质对应的空穴传输层100或能级调配层102或发光层104的平均活化能的计算过程可以为：首先获得各个物质的活化能Ea与其对应的摩尔质量分数乘积值；然后将上述各个乘积值进行求和，以获得平均活化能。或者，在其他实施方式中，也可直接对上述空穴传输层100、或能级调配层102或发光层104的整体进行热重分析，根据热重分析结果直接计算获得其对应的平均活化能。其中，热重分析是指在程序控制温度下，获得物质的质量随温度(或时间)的变化关系的方法；当利用热重分析技术获得热重曲线后，通过差减微分(Freeman-Carroll)法或积分(OWAZa)法等即可计算获得平均活化能。
现有技术中一般利用最高占据能级轨道HOMO/最低占据能级轨道LOMO来衡量发光器件10的能级匹配情况，HOMO/LOMO仅考虑了空穴的注入效率；而本申请中利用平均活化能来衡量发光器件10中能级匹配情况，能够综合考虑空穴的注入效率和迁移效率，相比传统的HOMO/LOMO的方式，可以延长发光器件10的寿命，使得发光器件10的发光效率提升。
在本实施例中，上述能级调配层102可以为电子阻挡层，其材质可以为含有螺芴基团的单个芳胺结构、含有螺环单元的单个芳胺结构等。上述能级调配层102的设计方式不仅可以起到能级匹配的目的，而且能够阻挡阴极的电子，以进一步提高发光器件10的发光效率。
此外，上述空穴传输层100的材质可以为聚对苯撑乙烯类、聚噻吩类、聚硅烷类、三苯甲烷类、三芳胺类、腙类、吡唑啉类、嚼唑类、咔唑类、丁二烯类等。
在一个实施方式中，当上述发光层104为蓝色发光层时，其第一差值ΔEa1的绝对值大于等于第二差值ΔEa2的绝对值。该设计方式可以使得集中于能级调配层102和发光层104的界面处的空穴数量低于空穴传输层100和能级调配层102的界面处的空穴数量，避免空穴过于集中在发光层104界面，减缓发光材料劣化，进而提高发光器件10的寿命。
在一个应用场景中，当上述发光层104为蓝色发光层时，第一差值ΔEa1的绝对值大于等于0.1eV且小于等于0.15eV，第二差值ΔEa2的绝对值大于等于 0.05eV且小于等于0.1eV。例如，上述第一差值ΔEa1的绝对值可以为0.12eV、0.14eV等，上述第二差值ΔEa2的绝对值可以为0.06eV、0.08eV等。上述第一差值ΔEa1和第二差值ΔEa2范围的设计方式可以有效提升蓝色发光层的寿命，降低蓝色发光层与红色发光层和绿色发光层之间的寿命差异，降低色偏发生的概率。
例如，上述能级调配层102的平均活化能相比空穴传输层100的平均活化能而言，具有-0.1eV至-0.2eV(例如，-0.15eV、-0.18eV等)的差值，蓝色发光层的平均活化能相比空穴传输层100的平均活化能而言，具有-0.2eV至-0.3eV(例如，-0.25eV、-0.28eV等)的差值。上述设计方式可以使得蓝色发光器件的寿命和发光效率较高。
为了验证上述设计的实际效果，设计了如下对比例1和实验例1，其中，实验例1中空穴传输层100和能级调配层102的平均活化能的第一差值ΔEa1的绝对值为0.1eV，能级调配层102和蓝色发光层104中的主体材料的平均活化能的第二差值ΔEa2的绝对值为0.05eV。对比例1和实验例1的差别在于发光器件不包括能级调配层102。对比例1和实验例1对应的发光器件的性能检测结果如下表1所示。
表1 对比例1和实验例1对应的发光器件性能检测对照表
Figure PCTCN2021088792-appb-000001
从上述表1中内容可以看出，实验例1和对比例1对应的发光器件所发出的光线的色坐标CIEx、CIEy基本相同、发光器件的Von@1nits和Vd也基本相同，其中，Von@1nits指在微小亮度1nits时的电压值；Vd是指在操作亮度1200nits时的电压值。而实验例1的BI值相比对比例1而言提高了20％，实验例1在1200nits亮度下持续的时间相比对比例而言提高了28％，其中，BI为cd/A/CIEy，cd/A为发光效率，CIEy为CIExy1931的坐标，因为蓝光发光效率cd/A容易受CIEy数值影响，所以业界一般定义蓝光效率会用BI值。从上述性能检测结果可以看出，本申请所采用的方案可以明显提高蓝色发光器件的发光效率和发光寿命。
此外，请参阅图2，图2为实验例1和对比例1随时间变化的色坐标示意图。 从图2中可以明显看出，实验例1相比对比例1而言，蓝色发光器件随时间的推移其寿命提高，白光色坐标变化减小。
在一个应用场景中，当上述发光层104为蓝色发光层，且蓝色发光层包括蓝色发光主体材料BH和蓝色发光掺杂材料BD时，能级调配层102与蓝色发光掺杂材料BD的平均活化能之间具有第三差值ΔEa3，第三差值ΔEa3的绝对值小于第二差值ΔEa2的绝对值。其中，蓝色发光主体材料BH主要作用是传递能量和防止三线态能量淹灭，蓝色发光掺杂材料BD主要作用是负责发光。当蓝色发光层发光时，能量在蓝色发光主体材料BH和蓝色发光掺杂材料BD之间进行传递，上述平均活化能的设计方式可以使得能级调配层102所传输的空穴可以较为容易地到达蓝色发光掺杂材料BD，蓝色发光主体材料BH能够将能量有效传输至蓝色发光掺杂材料BD，降低能量回流的概率，保证发光效率。
此外，在本实施例中，蓝色发光主体材料BH的平均活化能相比空穴传输层100而言，具有-0.2eV至-0.3eV的差值；蓝色发光掺杂材料BD的平均活化能相比空穴传输层100而言，具有-0.2eV至-0.3eV的差值。该蓝色发光主体材料BH可以为咔唑基团衍生物、芳基硅衍生物、芳族衍生物、金属络合物衍生物等，蓝色发光掺杂材料BD可以为荧光掺杂材料(例如，卟啉类化合物、香豆素类染料、喹吖啶酮类化合物、芳胺类化合物等)或磷光掺杂材料(例如，含有金属铱的络合物等)等。
进一步，当第二差值ΔEa2的绝对值大于等于0.05eV且小于等于0.1eV时，上述能级调配层102与蓝色发光掺杂材料BD的平均活化能之间的第三差值ΔEa3的绝对值小于0.05eV，例如，第三差值ΔEa3的绝对值可以为0.04eV、0.03eV等。上述第二差值ΔEa2和第三差值ΔEa3的设计方式可以有效提升蓝色发光层的发光效率；例如，上述第二差值ΔEa2的设计方式有利于累积一定数量的空穴和电子，空穴和电子再结合形成激子以提升发光效率；上述第三差值ΔEa3的设计方式有利于空穴从能级调配层102注入到蓝色发光掺杂材料BD中。
在另一个实施方式中，当上述发光层104为绿色发光层时，空穴传输层100和能级调配层102之间的第一差值ΔEa1的绝对值大于等于0.05eV且小于等于0.1eV，能级调配层102与发光层104绿色发光主体材料的平均活化能之间的第二差值ΔEa2的绝对值大于等于0.1eV且小于等于0.15eV。例如，上述第一差值ΔEa1的绝对值可以为0.06eV、0.08eV等，第二差值ΔEa2的绝对值可以为0.14eV、0.13eV等。上述第一差值ΔEa1和第二差值ΔEa2范围的设计方式可以 有效提升绿色发光器件的寿命和发光效率。
在一个应用场景中，绿色发光层也可以由绿色发光主体材料GH和绿色发光掺杂材料GD形成，能级调配层102与绿色掺杂材料GD的平均活化能之间具有第三差值ΔEa3，第三差值ΔEa3的绝对值小于0.05eV。且绿色发光主体材料GH与绿色发光掺杂材料GD的平均活化能之间具有0.08-0.12eV的绝对值差值。例如，绿色发光主体材料GH平均活化能相比空穴传输层100而言，具有0.15eV至0.2eV的差值，绿色发光掺杂材料GD的平均活化能相比空穴传输层100而言，具有0.05eV至0.15eV的差值，上述能级调配层102的平均活化能相比空穴传输层100的平均活化能而言，具有0.05eV至0.1eV(例如，0.06、0.08eV等)的差值。
在又一个实施方式中，当上述发光层104为红色发光层时，空穴传输层100和能级调配层102之间的第一差值ΔEa1的绝对值大于等于0.1eV且小于等于0.15eV，能级调配层102与发光层104的红色发光主体材料平均活化能之间的第二差值ΔEa2的绝对值小于0.05eV。例如，上述第一差值ΔEa1的绝对值可以为0.12eV、0.14eV等，上述第二差值ΔEa2的绝对值可以为0.04eV、0.03eV等。上述第一差值ΔEa1和第二差值ΔEa2范围的设计方式可以有效提升红色发光器件的寿命和发光效率。
在一个应用场景中，红色发光层也可以由红色发光主体材料RH和红色发光掺杂材料RD形成，能级调配层102与红色发光掺杂材料RD的平均活化能之间具有第三差值ΔEa3，第三差值ΔEa3的绝对值小于0.05eV。且红色发光主体材料RH与红色发光掺杂材料RD的平均活化能之间具有0.08-0.12eV的绝对值差值。例如，红色发光主体材料RH平均活化能相比空穴传输层100而言，具有0.20eV至0.25eV的差值，红色发光掺杂材料RD的平均活化能相比空穴传输层100而言，具有0.10eV至0.15eV的差值，上述能级调配层102的平均活化能相比空穴传输层100的平均活化能而言，具有0.10eV至0.15eV(例如，0.12、0.14eV等)的差值。
此外，当能级调配层102为电子阻挡层时，本申请所提供的发光器件还可以包括：第一能级层，位于电子阻挡层与发光层104之间，且第一能级层的平均活化能介于电子阻挡层和发光层104的平均活化能之间。该设计方式可以减缓电子阻挡层与发光层104界面冲击产生的寿命损失，提升发光器件的寿命。
和/或，第二能级层，位于电子阻挡层与空穴传输层100之间，且第二能级 层的平均活化能介于电子阻挡层和空穴传输层100的平均活化能之间。该设计方式可以减缓电子阻挡层与空穴传输层100界面冲击产生的寿命损失，提升发光器件的寿命。
另外，请再次参阅图1，图1中所给出的发光器件10为单层器件结构，其还可包括阴极108和阳极106。当然，在其他实施例中，其也可在图1中所示的发光层104与阴极108之间增加一层电子传输层。
或者，如图3所示，图3为本申请发光器件另一实施方式的结构示意图。上述发光器件10a除了包括图1中的结构层外，还可在图1中所示的发光层104a与阴极108a之间增加电子传输层103a和能级匹配层101a，且能级匹配层101a与发光层104a接触。上述发光器件10a的结构设计比较简单，且易于制备。其中，电子传输层103a与能级匹配层101a的平均活化能之间具有第四差值ΔEa4，能级匹配层101a与发光层104a的主体材料的平均活化能之间具有第五差值ΔEa4，第四差值ΔEa4的绝对值小于第五差值ΔEa5的绝对值。
现有技术中一般利用最高占据能级轨道HOMO/最低占据能级轨道LOMO来衡量发光器件10a的能级匹配情况，HOMO/LOMO仅考虑了电子或空穴的注入效率；而本申请中利用平均活化能来衡量发光器件10a中能级匹配情况，能够在综合考虑空穴的注入效率和迁移效率的基础上，进一步综合考虑温度、电子的注入效率和迁移效率，相比传统的HOMO/LOMO的方式，可以延长发光器件10a的寿命，使得发光器件10a的发光效率提升，且降低其发光效率随温度大幅度变化的现象。且上述设计方式中，通过电子和空穴两侧活化能的设计方式，可以降低电子累积于特定界面的概率，并达到较高效率的空穴/电子结合率，并使空穴/电子结合率随电流变化而改变的状态减缓。
在本实施例中，能级匹配层101a可以为空穴阻挡层，其材质可以为2，9-二甲基-4，7-二苯基-1，10-邻菲咯啉BCP、1,3,5-三(N-苯基-2-苯并咪唑)苯TPBi、三(8-羟基喹啉)合铝(III)Alq3、8-羟基喹啉-锂Liq、二(2-甲基-8-羟基喹啉)(4-苯基苯酚)合铝(III)BAlq、3-(联苯-4-基)-5-(4-叔丁基苯基)-4-苯基-4H-1,2,4-三唑TAZ等中至少一种。上述能级匹配层101a的设计方式不仅可以起到能级匹配的目的，而且能够阻挡阳极的空穴，以进一步提高发光器件10a的发光效率。
进一步，在选取能级匹配层101a的材质时，可以选取经历循环伏安测试的电流变化率小于1％的材质；其中，循环伏安测试的温度可以为室温或高于室温。该设计方式可以保证能级匹配层101a在长时间运转以及相应温度下的性能稳定 性，进而改善其在低灰阶时发光效率随温度变化的问题。
在一个实施方式中，上述发光层104a为蓝色发光层，电子传输层103a与能级匹配层101a的平均活化能之间的第四差值ΔEa4的绝对值小于0.05eV，能级匹配层101a与发光层104的主体材料的平均活化能之间的第五差值ΔEa5的绝对值大于等于0.1eV且小于等于0.15eV。上述第四差值ΔEa4的绝对值可以为0.02eV、0.04eV等，上述第五差值ΔEa5的绝对值可以为0.12eV、0.14eV等。上述第四差值ΔEa4和第五差值ΔEa5范围的设计方式可以有效提升蓝色发光层在不同温度下的发光效率，且降低不同温度下的发光效率的差值，进而降低白光偏移的情况。
在一个应用场景中，上述能级匹配层101a的平均活化能相比电子传输层103a的平均活化能而言，具有-0.05eV至0eV(例如，-0.02eV、-0.03eV等)的差值，蓝色发光层的主体材料的平均活化能相比电子传输层103a的平均活化能而言，具有0.05eV至0.15eV(例如，0.11eV、0.14eV等)的差值。上述设计方式可以使得蓝色发光器件的寿命和发光效率较高。
在一个应用场景中，上述蓝色发光层包括蓝色发光主体材料BH和蓝色发光掺杂材料BD，蓝色发光掺杂材料BD与能级匹配层101a的平均活化能之间具有第六差值ΔEa6，第六差值ΔEa6的绝对值小于第五差值ΔEa5的绝对值。其中，蓝色发光主体材料BH主要作用是传递能量和防止三线态能量淹灭，蓝色发光掺杂材料BD主要作用是负责发光。当蓝色发光层发光时，能量在蓝色发光主体材料BH和蓝色发光掺杂材料BD之间进行传递，上述平均活化能的设计方式可以使得能级匹配层101a所传输的电子可以较为容易地到达蓝色发光掺杂材料BD，蓝色发光主体材料BH能够将能量有效传输至蓝色发光掺杂材料BD，降低能量回流的概率，保证发光效率。
进一步，上述蓝色发光掺杂材料BD与能级匹配层101a的平均活化能之间的第六差值ΔEa6的绝对值小于0.05eV，例如，第六差值ΔEa6的绝对值可以为0.04eV，0.02eV等。与此同时，上述蓝色发光掺杂材料BD与蓝色发光主体材料BH的平均活化能之间的差值可以在0.05eV至0.1eV之间，例如，0.06eV、0.08eV等。上述第六差值ΔEa6和第五差值ΔEa5的设计方式可以有效提升蓝色发光层的发光效率；例如，上述第六差值ΔEa6的设计方式有利于累积一定数量的空穴和电子，空穴和电子再结合形成激子以提升发光效率；上述第五差值ΔEa5的设计方式有利于蓝色发光主体材料BH能够将能量有效传输至蓝色发光掺杂 材料BD，降低能量回流的概率，保证发光效率。
为了验证上述设计的实际效果，设计了如下对比例2和实验例2；
其中，对比例2中各层的活化能设计如下：蓝色发光主体材料BH与蓝色发光掺杂材料BD之间的平均活化能差值的绝对值为0.02eV,蓝色发光掺杂材料BD与能级匹配层101a之间的平均活化能差值的绝对值为0.02eV；蓝色发光主体材料BH与能级匹配层101a之间的平均活化能差值的绝对值为0.03eV,能级匹配层101a与电子传输层103a之间的平均活化能差值的绝对值为0.03eV。具体地，在该对比例中，蓝色发光主体材料BH、蓝色发光掺杂材料BD、能级匹配层101a的活化能相对电子传输层103a而言，差值均为正值。
实验例2中各层的活化能设计如下：蓝色发光主体材料BH与蓝色发光掺杂材料BD之间的平均活化能差值的绝对值为0.1eV，蓝色发光掺杂材料BD与能级匹配层101a之间的平均活化能差值的绝对值为0.04eV；蓝色发光主体材料BH与能级匹配层101a之间的平均活化能差值的绝对值为0.11eV,能级匹配层101a与电子传输层103a之间的平均活化能差值的绝对值为0.02eV。具体地，在该实验例2中，蓝色发光主体材料BH、蓝色发光掺杂材料BD的活化能相对电子传输层103a而言，差值均为正值；而能级匹配层101a的活化能相对电子传输层103a而言，差值为负值。
请参阅图4和图5，图4为对比例2中能级匹配层循环伏安曲线示意图，图5为实验例2中能级匹配层循环伏安曲线示意图。从图中可以看出，实验例2的能级匹配层材料在经历100次循环伏安后，其电流变化较小。经计算发现，对比例2的能级匹配层材料在经历100次循环伏安后，其电流变化率为4.4％，而实验例2的能级匹配层材料在经历100次循环伏安后，其电流变化率仅为0.5％。
请参阅图6和图7，图6为对比例2对应的发光器件随温度变化的发光效率曲线示意图，图7为实验例2对应的发光器件随温度变化的发光效率曲线示意图。从图中可以看出，实验例2的发光器件在各个温度下的发光效率变化明显小于对比例2的发光器件。且对比例2的发光效率小于实验例2，为达到相同的显示亮度，对比例2所需的驱动电流较大；例如，如图6和图7所示，为达到相同的亮度，对比例2中需要0.12mA/cm 2的电流密度，而实验例2需要0.108mA/cm 2的电流密度。
另外，经对比发现，对应于同一个电流密度0.12mA/cm 2，对比例2中的发光器件在55℃下的发光效率相对25℃下的发光效率降低，且为25℃下发光效率 的88.5％。对应于同一个电流密度0.108mA/cm 2，实验例2中的发光器件在55℃下的发光效率相对25℃下的发光效率增加，且为25℃下发光效率的111.6％。
进一步，请参阅图8，图8为对比例2和实验例2随温度变化的色坐标示意图。从图中可以看出，相对于对比例2而言，实验例2的白光随温度变化偏移较小。
上述实施例中主要针对发光层104a为蓝色发光层的情况，当然，对于其他颜色的发光层，上述方式同样适用。
例如，当发光层104a为绿色发光层时，能级匹配层101a与电子传输层103a的平均活化能之间的第四差值的绝对值小于0.05eV，绿色发光主体材料GH与能级匹配层101a的平均活化能之间的第五差值的绝对值小于0.05eV，绿色发光主体材料GH与绿色发光掺杂材料GD之间的平均活化能的差值的绝对值在0.05eV至0.1eV之间，绿色发光掺杂材料GD与能级匹配层101a之间的平均活化能的第六差值的绝对值小于0.1eV。在一个应用场景中，上述能级匹配层101a相对于电子传输层103a而言，具有大于0且小于0.05eV的平均活化能的差异；上述绿色发光主体材料相对于电子传输层103a而言，具有大于-0.05eV且小于0eV的平均活化能的差异；上述绿色发光掺杂材料相对于绿色发光主体材料而言，具有大于等于-0.1eV且小于等于-0.05eV的活化能的差异。
又例如，当发光层104a为红色发光层时，能级匹配层101a与电子传输层103a的平均活化能之间的第四差值的绝对值小于0.05eV，红色发光层的红色发光主体材料与能级匹配层101a的平均活化能之间的第五差值的绝对值小于0.05eV，红色发光主体材料RH与红色发光掺杂材料RD之间的平均活化能的差值的绝对值在0.08eV至0.12eV之间，红色发光掺杂材料RD与能级匹配层101a之间的平均活化能的第六差值的绝对值在0.08eV至0.12eV之间。在一个应用场景中，上述能级匹配层101a相对于电子传输层103a而言，具有大于0且小于0.05eV的平均活化能的差异；上述红色发光主体材料相对于电子传输层103a而言，具有大于0至0.05eV的平均活化能的差异；上述红色发光掺杂材料相对于红色发光主体材料而言，具有大于等于-0.1eV且小于等于0eV的活化能的差异。
此外，当能级匹配层101a为空穴阻挡层时，本申请所提供的发光器件还可以包括：第三能级层，位于空穴阻挡层与发光层104a之间，且第三能级层的平均活化能介于空穴阻挡层和发光层104a的平均活化能之间。该设计方式可以减缓空穴阻挡层与发光层104a界面冲击产生的寿命损失，提升发光器件的寿命。
和/或，第四能级层，位于空穴阻挡层与电子传输层103a之间，且第四能级层的平均活化能介于空穴阻挡层和电子传输层103a的平均活化能之间。该设计方式可以减缓空穴阻挡层与电子传输层103a界面冲击产生的寿命损失，提升发光器件的寿命。
请参阅图9，图9为本申请显示面板一实施方式的结构示意图。本申请所提供的显示面板20可以包括上述任一实施例中所提及的发光器件。其中，该显示面板20可以包括层叠设置的阵列基板200、发光层202、封装层204等。该发光层202中可以包含上述任一实施例中所提及的发光器件，该发光器件可以为蓝色发光器件、红色发光器件或绿色发光器件。
在本实施例中，当发光层202中包含蓝色发光器件、红色发光器件和绿色发光器件时，该蓝色发光器件、红色发光器件和绿色发光器件的空穴传输层可以由同一材质形成，而能级调配层可根据所设计的活化能要求选择不同的材质。该设计方式可以降低工艺制备的难度。当然，在其他实施例中，蓝色发光器件、红色发光器件和绿色发光器件的空穴传输层也可分别由不同材质形成，本申请对此不作限定。
以上所述仅为本申请的实施例，并非因此限制本申请的专利范围，凡是利用本申请说明书及附图内容所作的等效结构或等效流程变换，或直接或间接运用在其它相关的技术领域，均同理包括在本申请的专利保护范围内。

Claims (20)

  1. 一种发光器件，包括：
    层叠设置的空穴传输层、能级调配层和发光层，所述空穴传输层与所述能级调配层的平均活化能之间具有第一差值，所述能级调配层与所述发光层中的主体材料的平均活化能之间具有第二差值，所述第一差值的绝对值和所述第二差值的绝对值大于0eV。
  2. 根据权利要求1所述的发光器件，其中，
    所述发光层为蓝色发光层，所述第一差值的绝对值大于或等于所述第二差值的绝对值。
  3. 根据权利要求2所述的发光器件，其中，
    所述第一差值的绝对值大于或等于0.1eV且小于等于0.15eV，所述第二差值的绝对值大于或等于0.05eV且小于或等于0.1eV。
  4. 根据权利要求3所述的发光器件，其中，
    所述能级调配层的平均活化能相比所述空穴传输层的平均活化能而言，具有-0.1eV至-0.2eV的差值；
    所述蓝色发光层的平均活化能相比所述空穴传输层的平均活化能而言，具有-0.2eV至-0.3eV的差值。
  5. 根据权利要求3所述的发光器件，其中，
    所述蓝色发光层包括蓝色发光主体材料和蓝色发光掺杂材料，所述能级调配层与所述蓝色发光掺杂材料的平均活化能之间具有第三差值，所述第三差值的绝对值小于所述第二差值的绝对值。
  6. 根据权利要求5所述的发光器件，其中，
    所述第三差值的绝对值小于0.05eV。
  7. 根据权利要求5所述的发光器件，其中，
    所述蓝色发光主体材料的平均活化能相比所述空穴传输层的平均活化能而言，具有-0.2eV至-0.3eV的差值；
    所述蓝色发光掺杂材料的平均活化能相比所述空穴传输层的平均活化能而言，具有-0.2eV至-0.3eV的差值。
  8. 根据权利要求1所述的发光器件，其中，
    所述发光层为绿色发光层，所述第一差值的绝对值大于或等于0.05eV且小于或等于0.1eV，所述第二差值的绝对值大于或等于0.1eV且小于或等于 0.15eV。
  9. 根据权利要求8所述的发光器件，其中，
    所述绿色发光层包括绿色发光主体材料和绿色发光掺杂材料，所述能级调配层与所述绿色发光掺杂材料的平均活化能之间具有第三差值，所述第三差值的绝对值小于0.05eV。
  10. 根据权利要求9所述的发光器件，其中，
    所述绿色发光主体材料与所述绿色发光掺杂材料的平均活化能之间具有0.08-0.12eV的绝对值差值。
  11. 根据权利要求1所述的发光器件，其中，
    所述发光层为红色发光层，所述第一差值的绝对值大于或等于0.1eV且小于或等于0.15eV，所述第二差值的绝对值小于0.05eV。
  12. 根据权利要求11所述的发光器件，其中，
    所述红色发光层包括红色发光主体材料和红色发光掺杂材料，所述能级调配层与所述红色发光掺杂材料的平均活化能之间具有的第三差值，所述第三差值的绝对值小于0.05eV。
  13. 根据权利要求12所述的发光器件，其中，
    所述红色发光主体材料与所述红色发光掺杂材料的平均活化能之间具有0.08-0.12eV的绝对值差值。
  14. 根据权利要求1所述的发光器件，其中，
    所述能级调配层为电子阻挡层。
  15. 根据权利要求14所述的发光器件，其中，还包括：
    第一能级层，位于所述电子阻挡层与所述发光层之间，且所述第一能级层的平均活化能介于所述电子阻挡层和所述发光层的主体材料的平均活化能之间。
  16. 根据权利要求14所述的发光器件，其中，还包括：
    第二能级层，位于所述电子阻挡层与所述空穴传输层之间，且所述第二能级层的平均活化能介于所述电子阻挡层和所述空穴传输层的平均活化能之间。
  17. 根据权利要求1所述的发光器件，其中，还包括：
    能级匹配层，位于所述发光层背离所述能级调配层一侧；
    电子传输层，位于所述能级匹配层背离所述发光层一侧；
    其中，所述能级匹配层为空穴阻挡层，所述电子传输层与能级匹配层的平 均活化能之间具有第四差值，所述能级匹配层与所述发光层的主体材料的平均活化能之间具有第五差值，所述第四差值的绝对值小于第五差值的绝对值。
  18. 根据权利要求17所述的发光器件，其中，
    所述发光层为蓝色发光层，所述第四差值的绝对值小于0.05eV，所述第五差值的绝对值大于或等于0.1eV且小于或等于0.15eV。
  19. 根据权利要求18所述的发光器件，其中，
    所述蓝色发光层包括蓝色发光主体材料和蓝色发光掺杂材料，蓝色发光掺杂材料与所述能级匹配层的平均活化能之间具有第六差值，所述第六差值的绝对值小于所述第五差值的绝对值。
  20. 一种显示面板，包括权利要求1-19任一项所述的发光器件。
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CN114639788A (zh) * 2020-12-15 2022-06-17 云谷（固安）科技有限公司 发光器件、材料筛选方法及显示面板
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CN114639786A (zh) 2020-12-15 2022-06-17 云谷（固安）科技有限公司 发光器件及显示面板
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