WO2022127218A1 - 发光器件、材料筛选方法及显示面板 - Google Patents

发光器件、材料筛选方法及显示面板 Download PDF

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WO2022127218A1
WO2022127218A1 PCT/CN2021/117824 CN2021117824W WO2022127218A1 WO 2022127218 A1 WO2022127218 A1 WO 2022127218A1 CN 2021117824 W CN2021117824 W CN 2021117824W WO 2022127218 A1 WO2022127218 A1 WO 2022127218A1
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light
emitting
layer
emitting device
transport layer
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PCT/CN2021/117824
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English (en)
French (fr)
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高宇
刘孟宇
黄智�
王晓文
刘俊哲
孙佳欣
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云谷（固安）科技有限公司
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Priority to JP2023519059A priority Critical patent/JP2023543008A/ja
Priority to EP21905150.5A priority patent/EP4207324A4/en
Priority to KR1020237009498A priority patent/KR20230047194A/ko
Publication of WO2022127218A1 publication Critical patent/WO2022127218A1/zh
Priority to US18/178,826 priority patent/US20230209981A1/en

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    • 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
    • H10K71/70—Testing, e.g. accelerated lifetime tests
    • 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
    • H10K50/12—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising dopants
    • 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]
    • H10K50/14—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
    • H10K50/10—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
    • 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
    • H10K2101/10—Triplet emission
    • 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

Definitions

  • the present application relates to the field of display technology, and in particular, to a light-emitting device, a material screening method and a display panel.
  • organic light-emitting diode Organic Light-Emitting Diode, OLED
  • OLED Organic Light-Emitting Diode
  • the present application provides a light-emitting device, comprising:
  • Light-emitting layer including host material and guest material
  • the luminous efficiency is improved and the operating voltage of the light-emitting device is reduced in the high-brightness display state, and the overall power consumption of the display panel is reduced while ensuring the display quality of the display panel in the high-brightness state.
  • a material screening method provided in this application is used for screening the light-emitting layer materials of green or red light-emitting devices, including:
  • each luminescent material group includes a host material and a guest material, and at least one of the host material and the guest material included in each of the two luminescent material groups is different from each other;
  • each group of light-emitting material groups as the material of the light-emitting layer, a plurality of single-carrier devices with light-emitting layers are respectively fabricated;
  • a target light-emitting material group is obtained by screening from multiple groups of light-emitting material groups, which are used as light-emitting layer materials of the light-emitting device.
  • the light-emitting layer material selected by the material screening method provided by the present application can improve the light-emitting efficiency of the light-emitting device in the high-brightness display state, reduce the power consumption, ensure the display quality and display effect of the display panel in the high-brightness display state, and reduce the The overall power consumption of the display panel.
  • FIG. 1 is a diagram showing the relationship between activation energy levels of each functional layer on the hole injection side of the light-emitting device in an embodiment of the present application;
  • FIG. 2 is a diagram showing the relationship between activation energy levels of each functional layer on the electron injection side of the light-emitting device in another embodiment of the present application;
  • FIG. 3 is a graph showing the relationship between luminous efficiency and luminous brightness of a light-emitting device in a group of comparative experiments of the present application;
  • Fig. 5 is the step flow chart of the material screening method in an embodiment of the present application.
  • FIG. 6 is a flow chart of steps of a material screening method in another embodiment of the present application.
  • the inventor has found through in-depth research that when the display panel is developing in the direction of highlight display, the light-emitting device rolls off seriously in the highlight display state.
  • the general roll-off situation refers to the phenomenon in which the luminous efficiency of the light-emitting device gradually increases to the maximum value and then decreases during the process of continuous increase of the current density of the light-emitting device. In the stage of luminous efficiency decline, the faster the luminous efficiency decline rate, the more serious the roll-off is. A serious roll-off situation will not only affect the high-brightness display quality of the display panel, but also increase the power consumption of the display panel under low luminous efficiency, affecting the performance and life of the display panel.
  • the real brightness of the light emitting device is reduced to improve the brightness of the display panel.
  • the above method requires sacrificing the high pixel density of the display panel, and it is difficult to effectively improve the performance of the overall light emitting device.
  • an aspect of the present application provides a light-emitting device having a light-emitting layer including a host material and a guest material in the light-emitting layer.
  • a defect energy Et between the host material and the guest material, and the absolute value of the defect energy Et is greater than or equal to 0.03 eV.
  • the light-emitting device of the present application can improve the luminous efficiency while reducing the operating voltage of the light-emitting device in a high-brightness display state, thereby reducing the power consumption of the light-emitting device itself, thereby reducing the overall power consumption of the display panel.
  • the light-emitting layer of the light-emitting device is a phosphorescent light-emitting layer, wherein the guest material is a phosphorescent light-emitting material.
  • the light-emitting color of the light-emitting layer may be blue, red, green, or the like.
  • the light-emitting layer of the light-emitting device is a phosphorescent light-emitting layer
  • the guest material is a phosphorescent light-emitting material
  • the host material is a phosphorescent light-emitting host material
  • the light-emitting color of the light-emitting layer is any one of red or green.
  • the inventors have studied the green light-emitting device and the red light-emitting device and found that the light-emitting layer of the light-emitting device includes a host material and a guest material.
  • the guest material is doped in the host material.
  • electrons and holes are injected into the light-emitting layer from the electron injection direction and the hole injection direction respectively, and the guest material will form relative to the host material.
  • the carrier is trapped, so electrons and holes are not easily injected into the host material first, but are more easily injected directly into the guest material, and the carriers recombine on the guest material to form exciton emission.
  • the above-mentioned carrier traps have the capability of trapping carriers, that is, trapping holes and electrons, so the energy required to overcome the carrier traps when carriers are injected into the host material is the defect energy Et. It can also be understood that when carriers are injected into the light-emitting layer, there is a defect energy Et between the host material and the guest material. At the same time, the inventors have also found that controlling the defect energy Et within a certain preset range can improve the luminous efficiency of the light-emitting device and at the same time ensure the overall performance of the light-emitting device.
  • the absolute value of the defect energy Et ranges from 0.03 eV to 0.08 eV.
  • the following steps may be used to obtain the absolute value range of the energy Et a of the first standard defect state:
  • a plurality of test monochromatic light-emitting devices are fabricated, and the monochromatic light-emitting devices are tested to test a monochromatic light-emitting layer.
  • the materials of the light-emitting layers of the test monochromatic light-emitting devices are different from each other, and the structures and materials of the remaining functional layers are the same.
  • the material of the light-emitting layer of each tested monochromatic light-emitting device includes a host material and a guest material.
  • S02 Acquire test parameters of each test single-color light-emitting device, and use the first standard test parameter to screen to obtain a plurality of target test single-color light-emitting devices.
  • the first standard test parameter is a luminous efficiency parameter of the light emitting device.
  • the absolute value range of the first standard defect state energy Et a is determined according to the plurality of Et j .
  • the defect energy Et between the host material and the guest material can be calculated according to the following formula:
  • Equation 1 and Equation 2 Et is the defect energy, J is the current density, V is the preset voltage, k is the Boltzmann constant, and T is the preset temperature.
  • a single-carrier device including a light-emitting layer of the light-emitting device is fabricated, the light-emitting layer includes a host material and a guest material, and an electrification test is performed on the single-carrier device to obtain the single-carrier device at a preset temperature.
  • the I-V curve below is the current-voltage curve. Based on the current-voltage curve, the above equations (1) and (2) are used to calculate the defect energy Et between the host material and the guest material.
  • the light-emitting device further includes a hole transport layer disposed on the hole injection side of the light-emitting layer, and the activation energy of the host material and the hole transport layer has a first activation energy difference ⁇ Ea 1 ,
  • the value range of the absolute value of the first activation energy difference ⁇ Ea 1 is 0.1 eV to 0.3 eV.
  • the first activation energy difference ⁇ Ea 1 between the activation energies of the host material and the hole transport layer, and the first activation energy difference ⁇ Ea 1 >0 eV. That is, in the hole injection direction of the light-emitting layer, the activation energy of the host material is greater than the activation energy of the hole transport layer.
  • the value range of the first activation energy difference ⁇ Ea 1 is 0.1 eV to 0.3 eV.
  • the light-emitting device further includes a compensation layer disposed between the hole transport layer and the light-emitting layer, and in the hole injection direction of the light-emitting layer, the activation energy of the compensation layer is between the activation energy of the hole transport layer and the hole-transport layer. between the activation energy of the host material.
  • the activation energy of the compensation layer is between the activation energy of the hole transport layer and the activation energy of the host material.
  • the activation energy of the compensation layer in the hole injection direction of the light-emitting layer, is the same as the activation energy of the hole transport layer, and the activation energy of the compensation layer and the hole transport layer are both lower than the activation energy of the host material .
  • the activation energy of the compensation layer in the hole injection direction of the light-emitting layer, is higher than that of the hole transport layer and lower than that of the host material.
  • the activation energy of the compensation layer is higher than that of the hole transport layer and is the same as that of the host material.
  • the light-emitting device further includes an electron transport layer disposed on the electron injection side of the light-emitting layer, and the activation energy of the host material and the electron transport layer has a second activation energy difference ⁇ Ea 2 , and the second activation energy
  • the absolute value of the difference ⁇ Ea 2 ranges from 0.1 eV to 0.3 eV. In these examples, when the value of ⁇ Ea 2 is in the above reasonable range, it is avoided that a large amount of electrons accumulate in the light-emitting layer when the value of ⁇ Ea 2 is small, which affects the light-emitting performance of the light-emitting device, and also avoids that a large value of ⁇ Ea 2 affects the migration of electrons .
  • the activation energy of the host material is higher than that of the electron transport layer, and the second activation energy difference ⁇ Ea 2 ranges from 0.1 eV to 0.3 eV.
  • the light-emitting device further includes a hole blocking layer disposed between the electron transport layer and the light-emitting layer.
  • the activation energy of the hole blocking layer is between the activation energy of the electron transport layer and the activation energy of the host material. between.
  • the activation energy of the hole blocking layer is between the activation energy of the electron transport layer and the activation energy of the host material.
  • the activation energy of the hole blocking layer is the same as that of the electron transport layer, and the activation energy of the hole blocking layer and the electron transport layer are both lower than those of the host material.
  • the activation energy of the hole blocking layer is higher than that of the electron transport layer and lower than that of the host material.
  • the activation energy of the hole blocking layer is higher than that of the electron transport layer and is the same as that of the host material.
  • activation energy refers to the potential barrier that needs to be overcome for the transfer of electrons or holes between different functional layers of a light-emitting device.
  • the activation energy of a single or multiple functional layer can be understood as the potential barrier that electrons (or holes) need to overcome to flow from the cathode side (or anode side) through the single or multiple functional layer.
  • the above-mentioned functional layer refers to the carrier layer and the light-emitting layer in the light-emitting device.
  • the carrier layer in the light-emitting device includes an electron transport layer, a hole blocking layer, a compensation layer, a hole transport layer, a hole injection layer, and the like.
  • activation energy in this application can also be understood as the energy required for electrons to flow from the cathode side to the functional layer carrying electrons, and the energy required for holes to flow from the anode side to the functional layer carrying holes.
  • the activation energy difference can be understood as the energy required for carriers to flow from one functional layer to another in a certain carrier flow direction (eg, electron injection direction or hole injection direction).
  • the activation energy Ea of the material is the activation energy Ea corresponding to the functional layer.
  • the calculation method of the activation energy of the functional layer can be as follows: first obtain the product value of the activation energy of each material and the corresponding molar mass fraction of each material; The values are summed to obtain the overall activation energy of the functional layer, which can also be referred to as the weighted average activation energy.
  • the activation energy of the host material simply refers to the activation energy of the host material in the light-emitting layer.
  • a basic formula for calculating Ea is given in this application, and those skilled in the art can use the basic Arrhenius formula given in this application or the Arrhenius formula. ) formula is calculated to obtain Ea.
  • the activation energies of the carrier layer on the hole injection side of the light emitting layer and the light emitting layer, the activation energy difference between the carrier layers on the hole injection side, and the light emitting layer and the empty layer in the light emitting device are calculated.
  • the activation energy difference between the carrier layers on the hole injection side can be obtained by fabricating a single-hole device and conducting an electrification test on the single-hole device. Conduct a power-on test on the single-hole device to obtain the I-V curve (ie, the current-voltage curve) of the single-hole device. On the basis of obtaining the I-V curve of the single-hole device, use the Arrhenius formula or the Arrhenius formula. Activation energies are calculated from various variations of the Arrhenius formula.
  • the first single-hole device and the second single-hole device are fabricated.
  • a first single hole device with a hole transport layer is fabricated, and the first single hole device is energized and tested to obtain a first IV curve, and the Ea 1 of the hole transport layer is calculated by using the Arrhenius formula.
  • a second single-hole device with a hole transport layer and a light-emitting layer (with a host material) is fabricated, and the second single-hole device is energized and tested, so that holes flow from the hole transport layer to the light-emitting layer, and a second IV curve is obtained,
  • the Ea2 of the hole transport layer and the light emitting layer (with host material only) was calculated using the Arrhenius formula.
  • the first single hole device may include a stacked anode, a first hole transport layer, an electron blocking layer, and a cathode.
  • the second single hole device may include a stacked anode, a second hole transport layer, a light emitting layer (having only a host material), an electron blocking layer, and a cathode.
  • the first hole transport layer is the same as the second hole transport layer, and the first single hole device and the second single hole device are only tested with the light-emitting layer (with only the host material) as a single variable.
  • the electron blocking layer can prevent the electrons generated by the cathode from being transported in the single-hole device, so as to realize the purpose of allowing only hole transport in the single-hole device.
  • the activation energies of the carrier layer on the electron injection side of the light emitting layer and the light emitting layer, the activation energy difference between the carrier layers on the electron injection side, and the light emitting layer and the electron injection are calculated in the light emitting device
  • the activation energy difference between the side carrier layers can be obtained by fabricating a single-electron device and conducting an electrification test on the single-electron device.
  • the single-electron device is energized and tested to obtain the I-V curve (ie, the current-voltage curve) of the single-electron device.
  • the Arrhenius formula or the Arrhenius Activation energies are calculated by various variations of the Arrhenius formula.
  • the first single-electron device and the second electronic device are fabricated.
  • a first single-electron device with an electron transport layer is fabricated, and the first single-electron device is energized and tested to obtain a first I-V curve, and the Ea1' of the electron transport layer is calculated by using the Arrhenius formula.
  • a second single-electron device with an electron transport layer and a light-emitting layer (with only host material) is fabricated, and the second single-electron device is energized and tested, so that electrons flow from the electron transport layer to the light-emitting layer, and a second I-V curve is obtained, using Alleni
  • the Ea2' of the electron transport layer and the light emitting layer (with host material only) was calculated by the Arrhenius formula.
  • the first single electron device may include a stacked anode, a hole blocking layer, a first electron transport layer, and a cathode.
  • the second electronic device may include an anode, a hole blocking layer, a light emitting layer (having only a host material), a second electron transport layer, and a cathode arranged in layers.
  • the first electron transport layer is the same as the second electron transport layer, and the first single-electron device and the second single-electron device are only tested with the light-emitting layer (having only the host material) as a single variable.
  • the hole blocking layer can prevent the holes generated by the anode from being transported in the single-electron device, so that the single-electron device only allows electron transport.
  • the activation energy of the functional layer can be obtained by thermogravimetric analysis.
  • thermogravimetric analysis is performed on the entirety of the first carrier layer and the monochromatic light-emitting layer, and the activation energy of each functional layer is directly calculated and obtained according to the thermogravimetric analysis results.
  • Thermogravimetric analysis refers to a method of obtaining the relationship between the mass of a substance and temperature (or time) under a program-controlled temperature;
  • the average activation energy can be calculated by the integral (OWAZa) method.
  • the highest occupied energy level orbital HOMO and the lowest occupied energy level orbital LOMO are used to measure the energy level matching of each functional layer in a light-emitting device.
  • the HOMO energy level and the LUMO energy level only consider the injection efficiency of carriers, and neither the interface factors between the functional layers nor the temperature are considered. Designing and matching each functional layer in a light-emitting device only by the HOMO energy level and the LUMO energy level is likely to cause a large error between the performance parameters of the finished light-emitting device and the expected performance of the designed light-emitting device.
  • the defect energy Et between the host material and the guest material in the light-emitting layer has an effect on the luminous efficiency of the light-emitting device in the high-brightness display state. influences.
  • Using the defect energy Et between the host material and the guest material of the light-emitting layer to measure the matching relationship between the host material and the guest material of the light-emitting layer in the light-emitting device can more effectively improve the luminous efficiency of the light-emitting device.
  • the energy level matching relationship of the activation energy Ea of each functional layer in the light-emitting device is considered.
  • the influence of various factors such as carrier injection between functional layers, carrier transport between functional layers, and temperature on the overall performance of the light-emitting device in practical use.
  • the light-emitting device when carriers are injected into the light-emitting layer, the light-emitting device has defect energy Et between the host material and the guest material, and the absolute value of the defect energy Et is greater than or equal to 0.03 eV.
  • the absolute value of the first activation energy difference ⁇ Ea 1 ranges from 0.1 eV to 0.3 eV.
  • the light-emitting device further includes an electron transport layer disposed on the electron injection side of the light-emitting layer, the activation energy of the host material and the electron transport layer has a second activation energy difference ⁇ Ea 2 , and the absolute value of the second activation energy difference ⁇ Ea 2 is a value The range is 0.1eV to 0.3eV.
  • the light-emitting device considering both the defect energy Et and the activation energy Ea has a luminous efficiency compared to a light-emitting device that only satisfies the absolute value of the defect energy Et between the host material and the guest material is greater than or equal to 0.03 eV
  • the increase is 0% to 15%, and the luminous life is extended by 0% to 40%.
  • the comparative experiment includes Comparative Example 1 and Experimental Example 1.
  • Comparative Example 1 is a first red light-emitting device, and the absolute value of the defect energy Et1 between the host material and the guest material in the light-emitting layer of the first red light-emitting device is less than 0.03 eV.
  • Experimental Example 1 is a second red light-emitting device, and the absolute value of the defect energy Et2 between the host material and the guest material in the light-emitting layer of the second red light-emitting device is greater than 0.03 eV and less than 0.08 eV.
  • this set of comparative experiments only the defect energy Et between the host material and the guest material in the light-emitting layer of the red light-emitting device is used as a variable.
  • CIEx is the color coordinate, which refers to the red light emitted by the red light-emitting device.
  • L is the light emission luminance of the first red light emitting device and the second red light emitting device.
  • nits is a unit of luminous brightness. In the experimental test, both the first red light-emitting device and the second red light-emitting device are in a highlighted display state, and the brightness is 6000 nits.
  • Vd represents the operating voltage of the light-emitting device.
  • the operating voltage of the second red light-emitting device in Experimental Example 1 is lower than that of the first red light-emitting device in Comparative Example 1.
  • the operating voltage of a red light-emitting device is 0.03V lower than that of the second red light-emitting device in Experimental Example 1, so the power consumption of the second red light-emitting device is lower than that of the first red light-emitting device.
  • Eff. represents the luminous efficiency of the light-emitting device. It can be seen from Table 1 that the luminous efficiency of the second red light-emitting device is 10.2% higher than that of the first red light-emitting device.
  • FIG. 3 shows the relationship between the luminous efficiency and the luminous brightness of the first red light-emitting device and the second red light-emitting device in the test process in the comparative experiment. It can be seen from FIG. 3 that the luminous efficiency of the second red light emitting device is always higher than that of the first red light emitting device as the luminous brightness of the light emitting device increases.
  • Figure 4 shows the relationship between the working voltage and the luminous efficiency of the first red light-emitting device and the second red light-emitting device in the test process in the comparative experiment. It can be seen from Figure 4 that under the same light-emitting brightness, the first red light-emitting device The working voltage of is greater than the working voltage of the second red light-emitting device.
  • the light-emitting device In order to further reflect that when carriers are injected into the light-emitting layer, the light-emitting device satisfies: the host material and the guest material have a defect energy Et whose absolute value is greater than or equal to 0.03 eV; and the absolute value of the first activation energy difference ⁇ Ea 1 takes a value When the range is 0.1eV to 0.3eV, and/or, when the absolute value of the second activation energy difference ⁇ Ea 2 is in the range of 0.1eV to 0.3eV, the light-emitting device has more excellent light-emitting effect, and another set of comparative experiments was carried out. .
  • This set of comparative experiments includes one Comparative Example 2, and one Experimental Example 2, one Experimental Example 3, and one Experimental Example 4.
  • Comparative Example 2 Comparative Example 2, Experimental Example 2, Experimental Example 3 and Experimental Example 4 are all red light-emitting devices, and the light-emitting devices emit red light.
  • LT97@6000nits represents: when the initial light-emitting brightness is 6000 nits, the time it takes for the light-emitting brightness of the red light-emitting device to decay to 97% of the initial light-emitting brightness, LT97@6000nits represents the light-emitting life of the light-emitting device.
  • the luminous lifetime of Experimental Example 2 is 23% higher than that of Comparative Example 2, and the luminous lifetime of Experimental Example 3 is 20% higher than that of Comparative Example 2.
  • the luminous lifetime of Example 4 is 40% higher than that of Comparative Example 2.
  • Vd is the working voltage. Taking the working voltage in Comparative Example 2 as the reference value, the working voltage of Experimental Example 2 is 0.11V lower than that of Comparative Example 2, and the working voltage of Experimental Example 3 is 0.10V lower than that of Comparative Example 2. , the working voltage of Experimental Example 4 is 0.32V lower than that of Comparative Example 2.
  • the reduction of the operating voltage can reduce the power consumption of the light-emitting device in the process of emitting light, thereby reducing the overall display power consumption of the display panel.
  • the luminous efficiency of experimental example 2 is increased by 5% compared with that of comparative example 2
  • the luminous efficiency of experimental example 3 is increased by 4% compared to that of comparative example 2
  • the luminous efficiency of experimental example 4 Compared with the comparative example 2, it has increased by 12.2%.
  • the above data shows that the absolute value of the first activation energy difference ⁇ Ea 1 ranges from 0.1 eV to 0.3 eV on the basis that the light-emitting device satisfies the defect energy Et with an absolute value greater than or equal to 0.03 eV between the host material and the guest material.
  • the absolute value of the second activation energy difference ⁇ Ea 2 ranges from 0.1 eV to 0.3 eV, the luminous life of the light-emitting device is longer, the operating voltage is reduced, the power consumption is reduced, and the luminous efficiency of the light-emitting device is further improved improvement.
  • the embodiment of the present application further provides a material screening method, which is used for screening the light-emitting layer material of a green or red light-emitting device, as shown in FIG. 5, including the following steps:
  • each luminescent material group includes a host material and a guest material, and at least one of the host material and the guest material included in each of the two luminescent material groups is different from each other;
  • the single-carrier device is a single-hole device, and the single-carrier device further includes a hole transport layer stacked on the light-emitting layer and located on the hole injection side of the light-emitting layer , the hole transport layer of each single-carrier device is the same. In some embodiments, the hole transport layer of the light emitting device is the same as the hole transport layer of each single carrier device.
  • the single-carrier device is a single-electron device, and the single-carrier device further includes an electron transport layer stacked on the light-emitting layer and located on the electron injection side of the light-emitting layer.
  • Each single-carrier device The electron transport layer is the same.
  • the electron transport layer of the light emitting device is the same as the electron transport layer of each single carrier device.
  • the hole transport layer in the single hole device is the same as the hole transport layer in the light emitting device.
  • the hole transport layer is formed by evaporation of the whole layer in the display panel, which needs to match the working performance of the red, green and blue light-emitting devices. Therefore, when screening the material of the light-emitting layer, the same hole transport layer as that of the light-emitting device is set in the single-hole device, and the hole transport layer in the process of hole transport can be used for the defect between the host material of the light-emitting layer and the guest material in the light-emitting device.
  • the influence of energy Et is also considered, and the light-emitting layer material that improves the efficiency of the light-emitting device can be obtained more accurately by screening.
  • the electron transport layer in the single electron device is the same as the electron transport layer in the light emitting device.
  • the electron transport layer is formed by evaporation of the whole layer in the display panel, which needs to match the working performance of the red, green and blue light-emitting devices. Therefore, when screening the material of the light-emitting layer, setting the same electron transport layer as the light-emitting device in the single-electron device can reduce the influence of the electron transport layer on the defect energy Et between the host material of the light-emitting layer and the guest material in the light-emitting device during the electron transport process. Consideration is also being given to more accurate screening to obtain light-emitting layer materials that improve the efficiency of light-emitting devices.
  • step of S40 includes step S41,
  • Step S41 screening the target light-emitting material group by using the first standard defect state energy Eta .
  • the absolute value of the first standard defect state energy Eta ranges from 0.03 eV to 0.08 eV.
  • the light-emitting layer material selected by the material screening method provided by the present application can improve the light-emitting efficiency of the light-emitting device in the high-brightness display state, reduce the power consumption, ensure the display quality and display effect of the display panel in the high-brightness display state, and reduce the The overall power consumption of the display panel.
  • the display panel provided by the present application has the above-mentioned light-emitting device.
  • the display quality is improved while the power consumption is reduced in the highlighted display state.

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Abstract

一种发光器件、材料筛选方法以及显示面板。发光器件包括发光层，发光层包括主体材料和客体材料；载流子注入所述发光层时，所述主体材料和所述客体材料之间具有缺陷能量，所述缺陷能量的绝对值大于或等于0.03eV。发光器件在高亮显示状态下发光效率提升而发光器件的工作电压降低，可以保证显示面板高亮状态下显示质量同时，降低显示面板整体的功耗。

Description

发光器件、材料筛选方法及显示面板
相关申请的交叉引用
本申请要求享有于2020年12月15日提交的名称为“发光器件、材料筛选方法及显示面板”的中国专利申请第202011476865.7号的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及显示技术领域，具体涉及一种发光器件、材料筛选方法及显示面板。
背景技术
目前有机发光二极管(Organic Light-Emitting Diode，OLED)显示面板趋于高亮显示方向发展，因此急需提高在高亮显示状态下发光器件的发光效率。一般通过增大发光器件的开口面积提升发光效率，需要以牺牲像素密度为代价，也伴随显示面板功耗提升，从而影响显示面板的使用性能以及增大使用成本。
发明内容
本申请提供一种发光器件，包括：
发光层，包括主体材料和客体材料；
其中，载流子注入发光层时，主体材料和客体材料之间具有缺陷能量Et，缺陷能量Et的绝对值大于或等于0.03eV。
本申请提供的发光器件在高亮显示状态下发光效率提升而发光器件的工作电压降低，在保证显示面板高亮状态下显示质量同时，降低显示面板整体的功耗。
本申请提供的一种材料筛选方法，用于筛选绿色或红色发光器件的发 光层材料，包括：
配置多组发光材料组，各发光材料组包括主体材料和客体材料，每两组发光材料组包括的主体材料、客体材料中的至少一者彼此不同；
以每组发光材料组作为发光层材料，分别制作多个具有发光层的单载流子器件；
获取每组发光材料组对应的单载流子器件中，主体材料和客体材料之间的缺陷能量Eti；
根据每组发光材料组对应的缺陷能量Eti，从多组发光材料组中筛选得到目标发光材料组，以作为发光器件的发光层材料。
本申请提供的材料筛选方法筛选出的发光层材料可使得发光器件在高亮显示状态下发光效率提升，功耗得以下降，保证了显示面板高亮显示状态下的显示质量以及显示效果，同时减少显示面板的整体功耗。
附图说明
图1是本申请一种实施例中的发光器件在发光层空穴注入侧各功能层的活化能能级关系图；
图2是本申请另一种实施例中发光器件在发光层电子注入侧各功能层的活化能能级关系图；
图3是本申请一组对比实验中发光器件发光效率与发光亮度的关系曲线图；
图4是本申请一组对比实验中发光器件工作电压与发光效率的关系曲线图；
图5是本申请一实施例中材料筛选方法的步骤流程图；
图6是本申请另一实施例中材料筛选方法的步骤流程图。
具体实施方式
为了更好地理解本申请，下面结合图1至图6对本申请实施方式提供的发光器件、材料筛选方法以及显示面板进行详细描述。
发明人经深入研究发现，在显示面板处于高亮显示方向发展的情况 下，发光器件在高亮显示状态下滚降情况严重。一般滚降情况指发光器件在电流密度持续增大的过程中，发光效率逐渐增大到最大值后下降的现象。在发光效率下降阶段，发光效率下降速率越快说明滚降情况越严重。滚降情况严重不仅会影响显示面板的高亮显示质量，也会在低发光效率下使得显示面板的功耗增大，影响显示面板的使用性能以及寿命。
一般地，通过增大发光器件的像素开口面积降低发光器件的真实亮度以提升显示面板亮度，上述做法需要牺牲显示面板的高像素密度，难以有效地实现整体发光器件性能的提升。
因此，本申请的一方面提供一种发光器件，该发光器件具有发光层，发光层中包括主体材料和客体材料。载流子注入发光层时，主体材料和客体材料之间具有缺陷能量Et，缺陷能量Et的绝对值大于等于0.03eV。
本申请的发光器件可以在高亮显示状态下，提升发光效率，同时降低发光器件的工作电压，进而降低发光器件自身的功耗，从而实现显示面板整体功耗的降低。
在一实施例中，发光器件的发光层为磷光发光层，其中客体材料为磷光发光材料。在这些实施例中，发光层的发光颜色可以是蓝色、红色或绿色等。
在其他实施例中，发光器件的发光层为磷光发光层，客体材料为磷光发光材料，主体材料为磷光发光主体材料，且发光层的发光颜色为红色或绿色中的任意一种色光原色。
发明人对绿色的发光器件以及红色的发光器件研究发现，发光器件的发光层中包括主体材料和客体材料。一般客体材料是掺杂在主体材料中的，发光器件进行通电发光的过程中，电子以及空穴分别从电子注入方向以及空穴注入方向注入到发光层中，客体材料会形成相对于主体材料的载流子陷阱，因此电子和空穴不容易先注入到主体材料中而更容易直接注入到客体材料中，载流子在客体材料上复合形成激子发光。上述载流子陷阱具有捕获载流子，也即捕获空穴和电子的能力，因此载流子注入主体材料时克服载流子陷阱所需的能量为缺陷能量Et。也可以理解为载流子注入发光层时，主体材料和客体材料之间具有缺陷能量Et。发明人同时也研究得 出，控制缺陷能量Et在一定的预设范围内对于发光器件的发光效率有提升作用的同时，保证发光器件整体性能。
在一些可选的实施例中，缺陷能量Et的绝对值取值范围是0.03eV至0.08eV。
在本申请的实施例中，获取第一标准缺陷态能量Et a的绝对值范围可以采用以下步骤：
S01，制作多个测试单色发光器件，测试单色发光器件测试单色发光层，各测试单色发光器件的发光层材料互不相同，余下功能层的结构以及功能层材料均相同。
各测试单色发光器件的发光层材料包括主体材料和客体材料。
S02，获取各测试单色发光器件的测试参数，并利用第一标准测试参数筛选得到多个目标测试单色发光器件。
在一些实施例中，第一标准测试参数为发光器件的发光效率参数。
S03，获取各目标测试单色发光器件中，载流子注入各目标测试单色发光器件的发光层时、各发光层的主体材料和客体材料之间的缺陷能量Et j，j≥1，j为整数。
根据多个Et j确定第一标准缺陷态能量Et a的绝对值范围。
主体材料和客体材料之间的缺陷能量Et可以根据以下公式计算得到：
Et＝mkT        式(1)；
m＝logJ/logV   式(2)；
式1和式2中，Et为缺陷能量，J为电流密度，V为预设电压，k为玻尔兹曼常数，T为预设温度。
在一些示例中，制作包含发光器件的发光层的单载流子器件，上述发光层包括主体材料和客体材料，并对单载流子器件进行通电测试，得到单载流子器件在预设温度下的的I-V曲线，即电流-电压曲线。基于电流-电压曲线，采用上述式(1)和式(2)计算得到主体材料和客体材料之间的缺陷能量Et。
在一些可选的实施例中，发光器件还包括设置在发光层空穴注入侧的空穴传输层，主体材料与空穴传输层的活化能之间具有第一活化能差值Δ Ea 1，第一活化能差值ΔEa 1的绝对值的取值范围是0.1eV至0.3eV。
参见图1，主体材料与空穴传输层的活化能之间具有第一活化能差值ΔEa 1，第一活化能差值ΔEa 1>0eV。也即在发光层的空穴注入方向，主体材料的活化能大于空穴传输层的活化能。在一些示例中，第一活化能差值ΔEa 1的取值范围是0.1eV至0.3eV。在这些示例中，ΔEa 1的值处于上述合理范围时避免了ΔEa 1的值较小时大量的空穴在发光层中积聚影响发光器件的发光性能，也避免了ΔEa 1的值较大影响空穴的迁移。
在这些可选的实施例中，发光器件进一步包括设置在空穴传输层与发光层之间的补偿层，在发光层空穴注入方向，补偿层的活化能处于空穴传输层的活化能与主体材料的活化能之间。补偿层的活化能处于空穴传输层的活化能与主体材料的活化能之间。
在其他实施例中，在发光层空穴注入方向，补偿层的活化能与空穴传输层的活化能相同，且补偿层与空穴传输层的活化能均低于主体材料所具有的活化能。或者，在发光层空穴注入方向，补偿层的活化能高于空穴传输层的活化能而低于主体材料的活化能。或者，在发光层空穴注入方向，补偿层的活化能高于空穴传输层的活化能且与主体材料的活化能相同。
在一些可选的实施例中，发光器件还包括设置在发光层电子注入侧的电子传输层，主体材料与电子传输层的活化能之间具有第二活化能差值ΔEa 2，第二活化能差值ΔEa 2的绝对值取值范围是0.1eV至0.3eV。在这些示例中，ΔEa 2的值处于上述合理范围时避免了ΔEa 2的值较小时大量的电子在发光层中积聚影响发光器件的发光性能，也避免了ΔEa 2的值较大影响电子的迁移。
在一些实施例中，在发光层的电子注入方向，主体材料的活化能高于电子传输层的活化能，第二活化能差值ΔEa 2的取值范围是0.1eV至0.3eV。
参见图2，发光器件进一步包括设置在电子传输层与发光层之间的空穴阻挡层，在发光层电子注入方向，空穴阻挡层的活化能处于电子传输层的活化能与主体材料的活化能之间。
空穴阻挡层的活化能处于电子传输层的活化能与主体材料的活化能之 间。在发光层电子注入方向，空穴阻挡层的活化能与电子传输层的活化能相同，且空穴阻挡层与电子传输层的活化能均低于主体材料所具有的活化能。或者，在发光层电子注入方向，空穴阻挡层的活化能高于电子传输层的活化能而低于主体材料的活化能。或者，在发光层电子注入方向，空穴阻挡层的活化能高于电子传输层的活化能且与主体材料的活化能相同。
本申请中活化能是指电子或空穴在发光器件不同功能层之间转递需要克服的势垒。本申请中单层或多层功能层的活化能可以理解为电子(或者空穴)从阴极侧(或者阳极侧)流过单层或多层功能层所需要克服的势垒。上述的功能层指的是发光器件中的载流子层以及发光层。发光器件中的载流子层包括电子传输层、空穴阻挡层、补偿层、空穴传输层以及空穴注入层等。或者本申请中的活化能也可以理解为电子从阴极侧流过载流电子的功能层所需的能量，空穴从阳极侧流过载流空穴的功能层所需的能量。活化能差值可以理解成载流子在一定的载流子流动方向(例如电子注入方向或者空穴注入方向)从一个功能层流入到另一功能层所需的能量。
当功能层由单一材料构成，则该材料的活化能Ea即为该功能层对应的活化能Ea。当功能层由两种或两种以上的材料组成，则该功能层的活化能的计算方式可以为：首先获得各个材料的活化能与各个材料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，以获得功能层的整体活化能，也可以称之为加权平均活化能。发光层包括主体材料以及客体材料时，主体材料的活化能单指发光层中主体材料所具有的活化能。
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。即从上述公式可以看出，活化能与温度相关。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。可以理解的是，本申请中给出了计算Ea的一种基础公式，本领域技术人员可以基于本申请给出的基础阿伦尼乌斯(Arrhenius)公式或者由该阿伦尼乌斯(Arrhenius)公式的多种变形计算得到Ea。
在一些示例中，计算发光器件中位于发光层的空穴注入侧的载流子层和发光层的活化能、空穴注入侧的载流子层之间的活化能差值以及发光层与空穴注入侧的载流子层之间的活化能差值均可以通过制作单空穴器件，并对单空穴器件进行通电测试得到。对单空穴器件进行通电测试，得到单空穴器件的I-V曲线(即电流-电压曲线)，在得到单空穴器件的I-V曲线基础上采用阿伦尼乌斯(Arrhenius)公式或者该阿伦尼乌斯(Arrhenius)公式的多种变形计算得到活化能。
作为一个具体的例子，在计算发光器件中的主体材料与空穴传输层的活化能之间的活化能差值ΔEa时，制作第一单空穴器件和第二单空穴器件。制作具有空穴传输层的第一单空穴器件，对第一单空穴器件通电测试，得到第一I-V曲线，采用阿伦尼乌斯(Arrhenius)公式计算得到空穴传输层的Ea 1。制作具有空穴传输层和发光层(具有主体材料)的第二单空穴器件，对第二单空穴器件通电测试，使得空穴从空穴传输层流向发光层，得到第二I-V曲线，采用阿伦尼乌斯(Arrhenius)公式计算得到空穴传输层和发光层(仅具有主体材料)的Ea2。可利用差值计算法，即根据ΔEa＝Ea 2-Ea 1，计算得到发光器件中的主体材料与空穴传输层的活化能之间的差值ΔEa。
在一些示例中，单空穴器件仅允许空穴通过。第一单空穴器件可以包括层叠设置的阳极、第一空穴传输层、电子阻挡层以及阴极。第二单空穴器件可以包括层叠设置的阳极、第二空穴传输层、发光层(仅具有主体材料)、电子阻挡层以及阴极。＝第一空穴传输层与第二空穴传输层相同，第一单空穴器件与第二单空穴器件仅以发光层(仅具有主体材料)为单变量进行通电测试。又电子阻挡层能够阻碍阴极产生的电子在单空穴器件中传输，实现单空穴器件仅允许空穴传输的目的。
在一些实施例中，计算发光器件中位于发光层的电子注入侧的载流子层和发光层的活化能、电子注入侧的载流子层之间的活化能差值以及发光层与电子注入侧的载流子层之间的活化能差值均可以通过制作单电子器件，并对单电子器件进行通电测试得到。单电子器件进行通电测试，得到单电子器件的I-V曲线(即电流-电压曲线)，在得到单电子器件的I-V曲 线基础上采用阿伦尼乌斯(Arrhenius)公式或者该阿伦尼乌斯(Arrhenius)公式的多种变形计算得到活化能。
作为一个具体的例子，在计算发光器件中的主体材料与电子传输层的活化能之间的差值ΔEa’时，制作第一单电子器件和第二电子器件。制作具有电子传输层的第一单电子器件，对第一单电子器件通电测试，得到第一I-V曲线，采用阿伦尼乌斯(Arrhenius)公式计算得到电子传输层的Ea1’。制作具有电子传输层和发光层(仅具有主体材料)的第二单电子器件，对第二单电子器件通电测试，使得电子从电子传输层流向发光层，得到第二I-V曲线，采用阿伦尼乌斯(Arrhenius)公式计算得到电子传输层和发光层(仅具有主体材料)的Ea2’。可利用差值计算法，即根据ΔEa’＝Ea2’-Ea1’，计算得到发光器件中的主体材料与电子传输层的活化能之间的差值ΔEa’。
在一些示例中，单电子器件仅允许电子通过。第一单电子器件可以包括层叠设置的阳极、空穴阻挡层、第一电子传输层以及阴极。第二电子器件可以包括层叠设置的阳极、空穴阻挡层、发光层(仅具有主体材料)、第二电子传输层以及阴极。第一电子传输层与第二电子传输层相同，第一单电子器件与第二单电子器件仅以发光层(仅具有主体材料)为单变量进行通电测试。空穴阻挡层可以阻碍阳极产生的空穴在单电子器件中传输，实现单电子器件仅允许电子传输的目的。
在其他实施例中，功能层的活化能可以采用热重分析的方法得到。例如对第一载流子层以及单色发光层的整体进行热重分析，根据热重分析结果直接计算获得上述每一功能层的活化能。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。
一般利用最高占据能级轨道HOMO以及最低占据能级轨道LOMO来衡量发光器件中各功能层的能级匹配情况。然而HOMO能级以及LUMO能级仅考虑了载流子的注入效率，对功能层之间的界面因素以及温度等因素均未进行考虑。仅通过HOMO能级以及LUMO能级来对发光器件中各 功能层进行设计以及匹配容易造成成品发光器件的性能参数与设计的发光器件所应具有的预期性能有较大误差。
在本申请一些可选的实施例中，一方面在设计红色或者绿色发光器件时，发现了发光层中主体材料以及客体材料之间的缺陷能量Et对发光器件在高亮显示状态下发光效率的影响。利用发光层的主体材料和客体材料之间的缺陷能量Et衡量发光器件中的发光层的主体材料和客体材料之间的匹配关系，可以更有效的提升发光器件的发光效率。
在另一方面，在考虑发光层的主体材料和客体材料之间的缺陷能量Et的基础上更进一步的从活化能Ea方向着手，考虑发光器件中各功能层的活化能Ea的能级匹配关系。从活化能方向着手，能够综合考虑发光器件实际使用中的功能层之间载流子的注入、功能层之间载流子的传输以及温度等多方面因素对于发光器件整体性能的影响。
在一些实施例中，发光器件在载流子注入发光层时，主体材料和客体材料之间具有缺陷能量Et，缺陷能量Et的绝对值大于或等于0.03eV。并且主体材料与空穴传输层的活化能之间具有第一活化能差值ΔEa 1，第一活化能差值ΔEa 1的绝对值取值范围是0.1eV至0.3eV。
发光器件还包括设置在发光层电子注入侧的电子传输层，主体材料与电子传输层的活化能之间具有第二活化能差值ΔEa 2，第二活化能差值ΔEa 2的绝对值取值范围是0.1eV至0.3eV。在这些实施例中，从缺陷能量Et以及活化能Ea两方面均进行考虑的发光器件相较于单满足主体材料和客体材料之间缺陷能量Et绝对值大于或等于0.03eV的发光器件的发光效率提升0％～15％，发光寿命延长0％～40％。
为了体现本申请提供的发光器件在高亮显示状态下发光效率提升的效果，设计了如下一组对比实验。对比实验中包括对比例1以及实验例1。对比例1为第一红色发光器件，在该第一红色发光器件的发光层中主体材料和客体材料之间的缺陷能量Et1的绝对值小于0.03eV。实验例1为第二红色发光器件，在该第二红色发光器件的发光层中主体材料和客体材料之间的缺陷能量Et2的绝对值大于0.03eV且小于0.08eV。在该组对比实验中，仅以红色发光器件的发光层中主体材料和客体材料之间的缺陷能量Et 为变量进行实验。
表1对比例1和实验例1的测试实验结果
  缺陷能量Et CIEx L(nits) Vd(V) Eff.(cd/A)
对比例1 Et1<0.03eV 0.688 6000 Vd 0 100％
实验例1 0.03eV<Et2<0.08eV 0.684 6000 Vd 0-0.03V 110.2％
表1中CIEx为色坐标，指的是红色发光器件发出的红光。L为第一红色发光器件和第二红色发光器件的发光亮度。nits(尼特)为发光亮度的单位，在实验测试中第一红色发光器件和第二红色发光器件均处于高亮显示状态，亮度为6000nits。Vd代表发光器件的工作电压，以对比例1中的第一红色发光器件的工作电压为参照电压值Vd 0，实验例1中的第二红色发光器件的工作电压低于对比例1中的第一红色发光器件的工作电压，实验例1中第二红色发光器件的工作电压低了0.03V，从而第二红色发光器件的功耗低于第一红色发光器件。Eff.代表发光器件的发光效率，从表1可以看出第二红色发光器件的发光效率相较于第一红色发光器件的发光效率高出10.2％。
根据表1中展示的对比实验结果，本申请实施例发光器件载流子注入发光层时，主体材料和客体材料之间具有缺陷能量Et，且缺陷能量Et>0.03eV，可以提升发光器件在高亮显示状态下发光效率且降低发光器件的工作电压，发光器件的功耗降低进一步进而使得显示面板整体的功耗降低。
图3示出了对比实验中第一红色发光器件以及第二红色发光器件在测试过程中发光效率与发光亮度的关系曲线。从图3中可以看出随发光器件的发光亮度增大第二红色发光器件的发光效率总在第一红色发光器件的发光效率之上。
图4示出了对比实验中第一红色发光器件以及第二红色发光器件在测试过程中工作电压与发光效率的关系曲线.从图4中可以看出在同一发光亮度下，第一红色发光器件的工作电压大于第二红色发光器件的工作电压。
为了进一步体现在载流子注入发光层时，发光器件满足：主体材料和 客体材料之间具有绝对值大于或等于0.03eV的缺陷能量Et；且第一活化能差值ΔEa 1的绝对值取值范围为0.1eV至0.3eV，和/或，第二活化能差值ΔEa 2的绝对值取值范围为0.1eV至0.3eV时，发光器件具有更优异的发光效果，进行了另一组对比实验。该组对比实验中具有一个对比例2，和一个实验例2、一个实验例3以及一个实验例4。
表2对比例2和实验例2、3、4的测试实验结果
Figure PCTCN2021117824-appb-000001
从表2中色坐标值可以看出对比例2、实验例2、实验例3以及实验例4均为红色发光器件，发光器件发红光。LT97@6000nits表示：在初始发光亮度为6000尼特下，红色发光器件的发光亮度衰减到初始发光亮度的97％时所经历的时间，以LT97@6000nits代表该发光器件的发光寿命。
以对比例2中的发光器件的发光寿命为参照值，实验例2的发光寿命较对比例2的发光寿命提高23％，实验例3的发光寿命较对比例2的发光寿命提高20％，实验例4的发光寿命较对比例2的发光寿命提高40％。Vd为工作电压，以对比例2中的工作电压为参照值，实验例2的工作电压较对比例2的工作电压降低0.11V，实验例3的工作电压较对比例2的工作电压降低0.10V，实验例4的工作电压较对比例2的工作电压降低0.32V。工作电压降低可以使得发光器件在发光的过程中功耗降低，降低显示面板 整体的显示功耗。但是在发光器件功耗降低的同时，实验例2的发光效率相较于对比例2提升了5％，实验例3的发光效率相较于对比例2提升了4％，实验例4的发光效率相较于对比例2提升了12.2％。
上述数据说明在发光器件满足主体材料和客体材料之间具有绝对值大于或等于0.03eV的缺陷能量Et的基础上，第一活化能差值ΔEa 1的绝对值取值范围为0.1eV至0.3eV，和/或，第二活化能差值ΔEa 2的绝对值取值范围为0.1eV至0.3eV时，发光器件的发光寿命更长，且工作电压降低，功耗降低，发光器件发光效率得以进一步的提升。
本申请实施例另提供一种材料筛选方法，用于筛选绿色或红色发光器件的发光层材料，请参见图5，包括以下步骤：
S10，配置多组发光材料组，各发光材料组包括主体材料和客体材料，每两组发光材料组包括的主体材料、客体材料中的至少一者彼此不同；
S20，以每组发光材料组作为发光层材料，分别制作多个具有发光层的单载流子器件；
S30，获取每组发光材料组对应的单载流子器件中，主体材料和客体材料之间的缺陷能量Et i；
S40，根据每组发光材料组对应的缺陷能量Et i，从多组发光材料组中筛选得到目标发光材料组，以作为发光器件的发光层材料。
在一些可选的实施例中，在步骤S30中，单载流子器件为单空穴器件，单载流子器件还包括层叠设置于发光层且位于发光层空穴注入侧的空穴传输层，各单载流子器件的空穴传输层相同。在一些实施例中，发光器件的空穴传输层与各单载流子器件的空穴传层相同。
在另一些可选的实施例中，单载流子器件为单电子器件，单载流子器件还包括层叠设置于发光层且位于发光层电子注入侧的电子传输层，各单载流子器件的电子传输层相同。在一些实施例中，发光器件的电子传输层与各单载流子器件的电子传输层相同。
在一些示例中，单空穴器件中的空穴传输层与发光器件中的空穴传输层相同。一般空穴传输层在显示面板中整层蒸镀形成，需要配合红、绿以 及蓝三中发光器件的工作性能。因此在筛选发光层材料时，单空穴器件中设置与发光器件相同的空穴传输层，可以将空穴传输过程中空穴传输层对发光器件中发光层的主体材料以及客体材料之间的缺陷能量Et的影响也进行考虑，更准确地筛选得到提高发光器件效率的发光层材料。
在另一些示例中，单电子器件中的电子传输层与发光器件中的电子传输层相同。一般电子传输层在显示面板中整层蒸镀形成，需要配合红、绿以及蓝三中发光器件的工作性能。因此在筛选发光层材料时，单电子器件中设置与发光器件相同的电子传输层可以将电子传输过程中电子传输层对发光器件中发光层的主体材料以及客体材料之间的缺陷能量Et的影响也进行考虑，更准确地筛选得到提高发光器件效率的发光层材料。
参见图6，S40的步骤包括步骤S41，
步骤S41：利用第一标准缺陷态能量Et a筛选得到目标发光材料组。
在一些实施例中，第一标准缺陷态能量Et a的绝对值取值范围是0.03eV至0.08eV。
本申请提供的材料筛选方法筛选出的发光层材料可使得发光器件在高亮显示状态下发光效率提升，功耗得以下降，保证了显示面板高亮显示状态下的显示质量以及显示效果，同时减少显示面板的整体功耗。
本申请提供的显示面板，具有上述发光器件。本申请的显示面板在高亮显示状态下显示质量提升同时功耗下降。

Claims (18)

  1. 一种发光器件，包括：
    发光层，包括主体材料和客体材料，
    其中，载流子注入所述发光层时，所述主体材料和所述客体材料之间具有缺陷能量Et，所述缺陷能量Et的绝对值大于或等于0.03eV。
  2. 根据权利要求1所述的发光器件，其中，
    所述缺陷能量Et的绝对值取值范围是0.03eV至0.08eV。
  3. 根据权利要求1或2所述的发光器件，其中，
    所述发光层为磷光发光层，其中所述客体材料为磷光发光材料。
  4. 根据权利要求3所述的发光器件，其中，所述发光层发光颜色为红色或绿色中的任意一种色光原色。
  5. 根据权利要求1所述的发光器件，其中，
    所述发光器件还包括设置在所述发光层空穴注入侧的空穴传输层，
    所述主体材料与所述空穴传输层的活化能之间具有第一活化能差值ΔEa 1，所述第一活化能差值ΔEa 1的绝对值取值范围是0.1eV至0.3eV。
  6. 根据权利要求5所述的发光器件，其中，所述第一活化能差值ΔEa 1的取值范围是0.1eV至0.3eV。
  7. 根据权利要求5所述的发光器件，其中，
    所述发光器件进一步包括设置在所述空穴传输层与所述发光层之间的补偿层，
    在所述发光层空穴注入方向，所述补偿层的活化能处于所述空穴传输层的活化能与所述主体材料的活化能之间。
  8. 根据权利要求1至4任意一项所述的发光器件，其中，
    所述发光器件还包括设置在所述发光层电子注入侧的电子传输层，
    所述主体材料与所述电子传输层的活化能之间具有第二活化能差值ΔEa 2，所述第二活化能差值ΔEa 2的绝对值取值范围是0.1eV至0.3eV。
  9. 根据权利要求8所述的发光器件，其中，
    所述第二活化能差值ΔEa 2的取值范围是0.1eV至0.3eV。
  10. 根据权利要求8所述的发光器件，其中，
    所述发光器件进一步包括设置在所述电子传输层与所述发光层之间的空穴阻挡层，
    在所述发光层电子注入方向，所述空穴阻挡层的活化能处于所述电子传输层的活化能与所述主体材料的活化能之间。
  11. 一种材料筛选方法，用于筛选绿色或红色发光器件的发光层材料，包括：
    配置多组发光材料组，各所述发光材料组包括主体材料和客体材料，每两组所述发光材料组包括的所述主体材料、所述客体材料中的至少一者彼此不同；
    以每组所述发光材料组作为发光层材料，分别制作多个具有发光层的单载流子器件；
    获取每组所述发光材料组对应的所述单载流子器件中，所述主体材料和所述客体材料之间的缺陷能量Et i；
    根据每组所述发光材料组对应的所述缺陷能量Et i，从所述多组发光材料组中筛选得到目标发光材料组，以作为所述发光器件的发光层材料。
  12. 根据权利要求11所述的材料筛选方法，其中，所述单载流子器件为单空穴器件，所述单载流子器件还包括层叠设置于所述发光层且位于所述发光层空穴注入侧的空穴传输层，各所述单载流子器件的所述空穴传输层相同，
  13. 根据权利要求12所述的材料筛选方法，其中，所述发光器件的空穴传输层与各所述单载流子器件的空穴传输层相同。
  14. 根据权利要求11所述的材料筛选方法，其中，所述单载流子器件为单电子器件，所述单载流子器件还包括层叠设置于所述发光层且位于所述发光层电子注入侧的电子传输层，各所述单载流子器件的电子传输层相同。
  15. 根据权利要求14所述的材料筛选方法，其中，所述发光器件的电子传输层与各所述单载流子器件的电子传输层相同。
  16. 根据权利要求11所述的材料筛选方法，其中，在所述根据每组 所述发光材料组对应的所述缺陷能量Et i，从所述多组发光材料组中筛选得到目标发光材料组，以作为所述发光器件的发光层材料的步骤中包括：
    利用第一标准缺陷态能量Et a筛选得到所述目标发光材料组。
  17. 根据权利要求16所述的材料筛选方法，其中，所述第一标准缺陷态能量Et a的绝对值取值范围是0.03eV至0.08eV。
  18. 一种显示面板，包括权利要求1至10任意一项所述的发光器件。
PCT/CN2021/117824 2020-12-15 2021-09-10 发光器件、材料筛选方法及显示面板 WO2022127218A1 (zh)

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