WO2025000960A1 - 有机电致发光器件及显示装置 - Google Patents

有机电致发光器件及显示装置 Download PDF

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Publication number
WO2025000960A1
WO2025000960A1 PCT/CN2023/139388 CN2023139388W WO2025000960A1 WO 2025000960 A1 WO2025000960 A1 WO 2025000960A1 CN 2023139388 W CN2023139388 W CN 2023139388W WO 2025000960 A1 WO2025000960 A1 WO 2025000960A1
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Prior art keywords
layer
hole transport
refractive
low
light
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English (en)
French (fr)
Inventor
刘彬
宋原準
李梦真
逄辉
王宏宇
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Yungu Guan Technology Co Ltd
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Yungu Guan Technology Co Ltd
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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]
    • H10K50/14—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
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/10—OLED displays
    • H10K59/12—Active-matrix OLED [AMOLED] displays

Definitions

  • the present application relates to the field of display technology, and in particular to an organic electroluminescent device and a display apparatus.
  • OLEDs Organic light-emitting diodes
  • Laminated devices have light-emitting units stacked in multiple layers, and they are gradually gaining widespread attention and application. However, the current efficiency and other performance of existing laminated devices need to be further improved.
  • the present application provides an organic electroluminescent device and a display device, which can improve the current efficiency and other performance of the stacked device and effectively overcome the defects of the prior art.
  • an organic electroluminescent device comprising a plurality of light-emitting units stacked in layers, each of the light-emitting units comprising a hole transport region, a light-emitting layer and an electron transport region stacked in sequence, the hole transport region of at least one of the light-emitting units comprising a first low-refractive layer, the first low-refractive layer comprising a hole transport material having a refractive index less than 1.8.
  • Another aspect of the present application provides a display device, comprising the above-mentioned organic electroluminescent device.
  • the hole transport region of at least one light-emitting unit includes a first low-refractive layer, and the first low-refractive layer includes a hole transport material with a refractive index less than 1.8, which can effectively improve the current efficiency of the stacked device and also enable the stacked device to have both low driving voltage and high life performance.
  • FIG1 is a schematic structural diagram of an organic electroluminescent device according to an embodiment of the present application.
  • FIG. 2 is a schematic structural diagram of an organic electroluminescent device according to another embodiment of the present application.
  • the stacked device has multiple layers of stacked light-emitting units.
  • a charge generation layer (CGL) is usually set between each two adjacent light-emitting units to effectively distribute the charge to each light-emitting unit.
  • the charge generation layer has a PN junction, which includes an N-type charge generation layer (N-CGL) and a P-type charge generation layer (P-CGL) stacked in sequence. Due to the structure of the stacked device and the charge providing capacity of the film layer such as the charge generation layer, the current efficiency and other performance of the stacked device are relatively low.
  • the light-emitting layer in a stacked device is closer to the electrode, resulting in a greater surface plasmon polariton (SPP) quenching effect of the electrode, causing the stacked device to have higher optical losses and lower current efficiency.
  • SPP surface plasmon polariton
  • an embodiment of the present application provides an organic electroluminescent device, as shown in Figures 1 and 2, the organic electroluminescent device includes a plurality of light-emitting units stacked together, each light-emitting unit includes a hole transport region, a light-emitting layer and an electron transport region stacked in sequence, the hole transport region of at least one light-emitting unit includes a first low-refractive layer, and the first low-refractive layer includes a hole transport material having a refractive index less than 1.8.
  • the organic electroluminescent device of the embodiment of the present application is a stacked device, and a hole transport material with a refractive index less than 1.8 is introduced into the first low-refractive layer so that it can play a hole transport function.
  • a hole transport material with a refractive index less than 1.8 is introduced into the first low-refractive layer so that it can play a hole transport function.
  • the hole transport region of at least one light-emitting unit includes a first low-refractive layer, that is, a hole transport layer with a refractive index less than 1.8 is introduced into the hole transport region of at least one light-emitting unit.
  • the material can increase the distance between the light-emitting layer and the electrode while maintaining the thickness of the microcavity, weaken the SPP effect (or SPP quenching effect) of the electrode, thereby reducing the optical loss of the stacked device and improving its current efficiency and other performance.
  • the above-mentioned light-emitting layer can be a red light-emitting layer, a green light-emitting layer or a blue light-emitting layer.
  • the current efficiency and other performances of the red light stacked device (the light-emitting layer is the red light-emitting layer)
  • the green light stacked device (the light-emitting layer is the green light-emitting layer)
  • the blue light stacked device the light-emitting layer is the blue light-emitting layer
  • the green light-emitting layer and the blue light-emitting layer are more seriously affected by the SPP quenching effect of the electrode. Therefore, the current efficiency of the green light stacked device and the blue light stacked device is worse, and the embodiment of the present application can significantly improve the current efficiency and other performances of the green light stacked device and the blue light stacked device.
  • the refractive index of the hole transport material having a refractive index less than 1.8 may be greater than 1.2.
  • the refractive index of the hole transport material having a refractive index less than 1.8 is, for example, 1.25, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75 or a range consisting of any two of them.
  • the mass percentage of the hole transport material having a refractive index less than 1.8 is greater than or equal to 95%, for example, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, 100% (such as the hole transport layer and electron blocking layer described below) or a range consisting of any two of them, and the refractive index of the first low-refractive layer is substantially equal to the refractive index of the hole transport material therein, that is, the refractive index of the first low-refractive layer is less than 1.8, which is beneficial to further improve the current efficiency and other performance of the stacked device.
  • the refractive index refers to the refractive index for light with a wavelength of 450nm to 630nm.
  • the above-mentioned organic electroluminescent device also includes a first electrode and a second electrode stacked with the light-emitting unit, the above-mentioned multiple light-emitting units are located between the first electrode and the second electrode, and are stacked in sequence from the first electrode to the second electrode, the second electrode has an opposite polarity to the first electrode, for example, the first electrode is an anode, and the second electrode is a cathode, and in each light-emitting unit, its hole transport region is closer to the first electrode, and the electron transport region is closer to the second electrode.
  • the number of the light-emitting units can be two (the stacked device is a second-order microcavity structure), three (the stacked device is a third-order microcavity structure), four (the stacked device is a fourth-order microcavity structure), etc.
  • the number of its light-emitting units is two, namely, a first light-emitting unit and a second light-emitting unit stacked in sequence along the direction from the first electrode to the second electrode, and the first light-emitting unit is a plurality of light-emitting units.
  • the first light emitting unit includes a light emitting layer EML-1
  • the second light emitting unit includes a light emitting layer EML-2.
  • the above-mentioned organic electroluminescent device may further include a charge generation layer located between each two adjacent light-emitting units, and the charge generation layer includes an n-type charge generation layer n-CGL and a p-type charge generation layer p-CGL stacked in the direction from the first electrode to the second electrode, so that the charges can be effectively distributed to each light-emitting unit, thereby improving the current efficiency of each light-emitting unit.
  • the hole transport regions of the remaining light-emitting units may include or exclude the first low-refractive layer (that is, the refractive index of the hole transport material in the hole transport region is not less than 1.8).
  • the hole transport regions of these light-emitting units each include the first low-refractive layer (that is, the hole transport regions of the above-mentioned multiple light-emitting units (the first light-emitting unit and the second light-emitting unit as shown in Figures 1 and 2) each include the first low-refractive layer), which can further improve the current efficiency and other performances of the device.
  • the hole transport region may include one or more of a hole injection layer, a hole transport layer and an electron blocking layer.
  • the hole transport region of one or at least two light-emitting units may include a hole injection layer, and generally the hole transport region of the light-emitting unit closest to the first electrode (the first light-emitting unit as shown in Figures 1 and 2) includes a hole injection layer;
  • the hole transport region of one or at least two light-emitting units may include a hole transport layer, and preferably the hole transport region of each light-emitting unit (the first light-emitting unit and the second light-emitting unit as shown in Figures 1 and 2) includes a hole transport layer respectively;
  • the hole transport region of one or at least two light-emitting units may include an electron blocking layer, and preferably the hole transport region of each light-emitting unit (the first light-emitting unit and the second light-emitting unit as shown in Figures 1 and 2) includes an electron blocking
  • the hole transport region of the first light-emitting unit includes a hole injection layer HIL, a hole transport layer HTL-1 and an electron blocking layer EBL-1 stacked in sequence from the first electrode to the second electrode
  • the hole transport region of the second light-emitting unit includes a hole transport layer HTL-2 and an electron blocking layer EBL-2 stacked in the direction from the first electrode to the second electrode.
  • the hole injection layer, the hole transport layer and the electron blocking layer each include a hole transport material
  • the first low refractive layer may be at least one of the hole injection layer, the hole transport layer and the electron blocking layer. That is, the hole transport region of at least one light-emitting unit of the above-mentioned stacked device includes at least one of a hole injection layer of a hole transport material having a refractive index less than 1.8, a hole transport layer of a hole transport material having a refractive index less than 1.8, and an electron blocking layer of a hole transport material having a refractive index less than 1.8.
  • the hole transport region of the light-emitting unit closest to the first electrode (i.e., the hole transport region closest to the first electrode) (i.e., the hole transport region closest to the first electrode) includes a hole injection layer, which is a first low-refractive layer, i.e., the refractive index n1 of the hole transport material in the hole injection layer is less than 1.8; and/or, the hole transport region closest to the first electrode includes a hole transport layer, which is a first low-refractive layer, i.e., the refractive index n2 of the hole transport material in the hole transport layer is less than 1.8; and/or, the hole transport region closest to the first electrode includes an electron blocking layer, which is a first low-refractive layer, i.e., the refractive index n3 of the hole transport material in the electron blocking layer is less than 1.8.
  • the hole transport region of the light-emitting unit closest to the first electrode includes the first low-refractive layer, i.e
  • At least one of the hole injection layer HIL, the hole transport layer HTL-1 and the electron blocking layer EBL-1 in the hole transport region of the first light-emitting unit is a first low-refractive layer, so that the hole transport region of the light-emitting unit closest to the first electrode includes the first low-refractive layer.
  • the hole transport layer of the hole transport zone of each light-emitting unit is respectively the first low-refractive layer, that is, the refractive index n2 of the hole transport material in the hole transport layer of each light-emitting unit is respectively less than 1.8, which is conducive to further improving the current efficiency and other performances of the stacked device.
  • the refractive index of the hole transport material of these hole transport layers can be equal or unequal (in the stacked device shown in Figures 1 and 2, the refractive index of the hole transport material of the hole transport layer HTL-1 in the first light-emitting unit can be equal to or unequal to the refractive index of the hole transport material of the hole transport layer HTL-2 in the second light-emitting unit).
  • the electron blocking layer in the hole transport region of each light-emitting unit is respectively the first low-refractive layer, that is, the refractive index n3 of the hole transport material in the electron blocking layer of each light-emitting unit is respectively less than 1.8, which is conducive to further improving the performance of the stacked device such as the luminous efficiency.
  • the refractive index of the hole transport material of these electron blocking layers can be equal or unequal (in the stacked device shown in Figures 1 and 2, the refractive index of the hole transport material of the electron blocking layer EBL-1 in the first light-emitting unit can be equal to or unequal to the refractive index of the hole transport material of the electron blocking layer EBL-2 in the second light-emitting unit).
  • the first low-refractive layer is a hole injection layer.
  • the refractive index of hole transport material with a refractive index less than 1.8 is n 1 (i.e., n 1 ⁇ 1.8)
  • the thickness of the first low-refractive layer is H 1 , and 6nm ⁇ n 1 ⁇ H 1 ⁇ 54nm.
  • the hole transport region of at least one light-emitting unit of the stacked device includes a hole injection layer with a refractive index of hole transport material less than 1.8
  • the thickness H 1 of the hole injection layer and the refractive index n 1 of the hole transport material satisfy 6nm ⁇ n 1 ⁇ H 1 ⁇ 54nm, which is conducive to further improving the efficiency and other performances of the stacked device.
  • controlling the layer product of n 1 and H 1 i.e., n 1 ⁇ H 1
  • the hole injection layer have more suitable optical thickness and other properties, thereby further optimizing the performance of the stacked device.
  • n 1 ⁇ H 1 may be 7 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 53 nm, or a range consisting of any two thereof.
  • the refractive index n1 of the hole transport material is, for example, 1.25, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75 or a range consisting of any two thereof.
  • the thickness H1 of the hole injection layer having a refractive index of less than 1.8 of the hole transport material may be 5 nm to 30 nm, for example, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm or any two thereof.
  • the thickness H 1 of the hole injection layer HIL may be 5 nm to 30 nm, and may satisfy 6 nm ⁇ n 1 ⁇ H 1 ⁇ 54 nm.
  • the first low-refractive layer is a hole transport layer.
  • the refractive index of hole transport material whose refractive index is less than 1.8 is n 2 (i.e., n 2 ⁇ 1.8).
  • the thickness of the first low-refractive layer is H 2 , and 6nm ⁇ n 2 ⁇ H 2 ⁇ 360nm.
  • the hole transport region of at least one light-emitting unit of the stacked device includes a hole transport layer whose refractive index of hole transport material is less than 1.8
  • the thickness H 2 of the hole transport layer and the refractive index n 2 of the hole transport material satisfy 6nm ⁇ n 2 ⁇ H 2 ⁇ 360nm, which is conducive to further improving the efficiency and other performances of the stacked device.
  • controlling the layer product of n 2 and H 2 i.e., n 2 ⁇ H 2
  • the hole transport layer have more suitable optical thickness and other properties, thereby further optimizing the performance of the stacked device.
  • n 2 ⁇ H 2 may be 7 nm, 10 nm, 30 nm, 50 nm, 70 nm, 100 nm, 130 nm, 150 nm, 180 nm, 200 nm, 230 nm, 250 nm, 280 nm, 300 nm, 330 nm, 355 nm, or a range consisting of any two thereof.
  • the refractive index n2 of the hole transport material is, for example, 1.25, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75 or a range consisting of any two thereof.
  • the thickness H2 of the hole transport layer having a refractive index of less than 1.8 can be 5 nm to 200 nm, for example, 5 nm, 30 nm, 50 nm, 80 nm, 100 nm, 130 nm, 150 nm, 180 nm, 200 nm or a range consisting of any two thereof.
  • the hole transport layer HTL-1 of the first light-emitting unit may be the first low-refractive layer.
  • the refractive index of the hole transport material of the hole transport layer HTL-1 of the first light-emitting unit is n 2 ⁇ 1.8
  • the thickness H 2 of the hole transport layer HTL-1 may be 5 nm to 200 nm, and may satisfy 6 nm ⁇ n 2 ⁇ H 2 ⁇ 360 nm; or the hole transport layer HTL-2 of the second light-emitting unit may be the first low-refractive layer.
  • the refractive index of the hole transport material of the hole transport layer HTL-2 of the second light-emitting unit is n 2 ⁇ 1.8
  • the thickness H 2 of the hole transport layer HTL-2 may be 5 nm to 200 nm, and may satisfy 6 nm ⁇ n 2 ⁇ H 2 ⁇ 360nm; or the hole transport layer HTL-1 of the first light-emitting unit and the hole transport layer HTL-2 of the second light-emitting unit are both first low-refractive layers.
  • the hole transport layer HTL-1 of the first light-emitting unit and the hole transport layer HTL-2 of the second light-emitting unit can respectively satisfy: the refractive index of the hole transport material n 2 ⁇ 1.8, the thickness H 2 of the hole transport layer can be 5nm ⁇ 200nm, 6nm ⁇ n 2 ⁇ H 2 ⁇ 360nm.
  • the first low-refractive layer is an electron blocking layer.
  • the refractive index of the hole transport material whose refractive index is less than 1.8 is n 3 (i.e., n 3 ⁇ 1.8).
  • the thickness of the first low-refractive layer is H 3 , and 6nm ⁇ n 3 ⁇ H 3 ⁇ 54nm.
  • the hole transport region of at least one light-emitting unit of the stacked device includes the electron blocking layer whose refractive index of the hole transport material is less than 1.8
  • the thickness H 3 of the electron blocking layer and the refractive index n 3 of the hole transport material satisfy 6nm ⁇ n 3 ⁇ H 3 ⁇ 54nm. This is conducive to further improving the efficiency and other performances of the stacked device.
  • controlling the layer product of n 3 and H 3 i.e., n 3 ⁇ H 3
  • the electron blocking layer have more suitable optical thickness and other properties, thereby further optimizing the performance of the stacked device.
  • n 3 ⁇ H 3 may be 7 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, The range is 35nm, 40nm, 45nm, 50nm, 53nm or any two thereof.
  • the refractive index n3 of the hole transport material is, for example, 1.25, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75 or a range consisting of any two thereof.
  • the thickness H3 of the electron blocking layer of the hole transport material having a refractive index less than 1.8 can be 3 nm to 50 nm, for example, 3 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm or a range consisting of any two thereof.
  • the electron blocking layer EBL-1 of the first light-emitting unit may be the first low-refractive layer.
  • the refractive index n 3 of the hole transport material of the electron blocking layer EBL-1 of the first light-emitting unit is ⁇ 1.8
  • the thickness H 3 of the electron blocking layer EBL-1 may be 3 nm to 50 nm, and may satisfy 6 nm ⁇ n 3 ⁇ H 3 ⁇ 54 nm; or the electron blocking layer EBL-2 of the second light-emitting unit is the first low-refractive layer.
  • the refractive index n 2 of the hole transport material of the electron blocking layer EBL-2 of the second light-emitting unit is ⁇ 1.8
  • the thickness H 2 of the electron blocking layer EBL-2 may be 3 nm to 50 nm, and may satisfy 6 nm ⁇ n 3 ⁇ H 3 ⁇ 54nm; or the electron blocking layer EBL-1 of the first light-emitting unit and the electron blocking layer EBL-2 of the second light-emitting unit are both first low-refractive layers, in which case the electron blocking layer EBL-1 of the first light-emitting unit and the electron blocking layer EBL-2 of the second light-emitting unit can both satisfy: the refractive index of the hole transport material n 3 ⁇ 1.8, the thickness H 3 of the electron blocking layer can be 3nm ⁇ 50nm, 6nm ⁇ n 3 ⁇ H 3 ⁇ 54nm.
  • the mass percentage of the hole transport material in the hole injection layer, the hole transport layer and the electron blocking layer can be independently greater than or equal to 95%.
  • the mass percentage of the hole transport material in the hole transport layer is 100% (i.e., the hole transport layer is entirely formed of the hole transport material), and the mass percentage of the hole transport material in the electron blocking layer is 100% (i.e., the electron blocking layer is entirely formed of the hole transport material).
  • the refractive index or hole mobility of these layers is basically consistent with the hole transport material included therein.
  • the hole injection layer may include a first p-type doping material.
  • the mass percentage of the first p-type doping material may be 0.5% to 5%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or any two thereof. This can improve the hole transport capacity of the hole injection layer and further optimize the performance of the stacked device.
  • the refractive index of the hole injection layer (the hole injection layer whose refractive index of the hole transport material is less than 1.8) is basically not affected, that is, the refractive index of the hole injection layer is basically equal to the refractive index of the hole transport material therein, that is, the refractive index of the hole injection layer is less than 1.8, which is beneficial to further improve the current efficiency and other performance of the stacked device.
  • the above-mentioned organic electroluminescent device also includes a first adjacent layer adjacent to the first low-refractive layer, the first adjacent layer adjacent to the first low-refractive layer is in direct contact with the first low-refractive layer, and there is no other film layer between the two.
  • the refractive index of the first low-refractive layer is greater than or less than the refractive index of the first adjacent layer.
  • the difference between the refractive index of the first low-refractive layer and the refractive index of the first adjacent layer can be specifically less than or equal to 0.5, for example, less than or equal to 0.4, less than or equal to 0.3, less than or equal to 0.2, less than or equal to 0.1, etc., so that the adverse effects such as interface reflection caused by the excessive refractive index of the first low-refractive layer and the first adjacent layer can be prevented, thereby further optimizing the microcavity effect and improving the current efficiency and other performance of the device.
  • the difference between the refractive index of the first low-refractive layer and the refractive index of the first adjacent layer is 0, 0.01, 0.03, 0.05, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 or a range consisting of any two thereof.
  • the first adjacent layer may be located on one side of the first low-refractive layer (e.g., located on the side of the first low-refractive layer facing the first electrode, or located on the side of the first low-refractive layer facing the second electrode), or may be located on two opposite sides of the first low-refractive layer (i.e., the refractive index of the film layers on the two opposite sides of the first low-refractive layer is different from the refractive index of the first low-refractive layer, for example, the difference between the refractive index of the film layers on the two opposite sides of the first low-refractive layer and the refractive index of the first low-refractive layer is less than or equal to 0.5, and the two opposite sides are respectively the side of the first low-refractive layer facing the first electrode and the side of the first low-refractive layer facing the second electrode).
  • the refractive index of the film layers on the two opposite sides of the first low-refractive layer is different from the refractive index of the first
  • the first low-refractive layer is a hole injection layer
  • the first adjacent layer may be a hole transport layer.
  • the hole injection layer HIL is the first low-refractive layer
  • the first adjacent layer of the hole injection layer HIL is the hole transport layer HTL-1 (i.e., the refractive index of the hole injection layer HIL is greater than or less than the refractive index of the hole transport layer HTL-1).
  • the first low-refractive layer is a hole transport layer
  • the first adjacent layer includes a hole injection layer adjacent to one side of the first low-refractive layer (the side facing the first electrode), and an electron blocking layer or a light-emitting layer adjacent to the other side of the first low-refractive layer (the side facing the second electrode).
  • the hole transport region includes a hole injection layer, a hole transport layer and an electron blocking layer stacked in sequence, and the hole transport layer is the first low-refractive layer
  • the first adjacent layers on opposite sides of the hole transport layer are the hole injection layer and the electron blocking layer (i.e., the refractive index of the hole transport layer is greater than or less than the refractive index of the hole injection layer, and greater than or equal to the refractive index of the electron blocking layer).
  • the first adjacent layers include the hole injection layer HIL and the electron blocking layer EBL-1.
  • the hole transport layer is composed of a stacked hole injection layer and a hole transport layer (no electron blocking layer is provided), and the hole transport layer is the first low refractive layer, the hole transport layer is located between the hole injection layer and the light-emitting layer, and the first adjacent layers on the opposite sides thereof are the hole injection layer and the light-emitting layer, respectively (i.e., the refractive index of the hole transport layer is greater than or less than the refractive index of the hole injection layer, and greater than or equal to the refractive index of the light-emitting layer adjacent thereto).
  • the hole transport region of one or several light-emitting units in the stacked device may not include a hole injection layer (such as the hole transport region of the second light-emitting unit shown in Figures 1 and 2).
  • These hole transport regions are, for example, only provided with a hole transport layer.
  • the hole transport layer is the first low-refractive layer
  • its first adjacent layer is the light-emitting layer adjacent thereto; or, these hole transport regions include a hole transport layer and an electron blocking layer.
  • its first adjacent layer includes a p-type charge generation layer adjacent thereto on one side and an electron blocking layer adjacent thereto on the other side.
  • the p-type charge generation layer and the electron blocking layer are respectively located on opposite sides of the hole transport layer.
  • the first adjacent layer includes a p-type charge generation layer p-CGL and an electron blocking layer EBL-2.
  • the first low-refractive layer is an electron blocking layer
  • the first adjacent layer includes a hole transport layer adjacent to one side of the first low-refractive layer, and a light-emitting layer adjacent to the other side of the first low-refractive layer.
  • the electron blocking layer EBL-1 is located between the hole transport layer HTL-1 and the light-emitting layer EML-1.
  • the electron blocking layer EBL-1 is the first low-refractive layer
  • the first adjacent layers on opposite sides thereof are the hole transport layer HTL-1 and the light-emitting layer EML-1, respectively (i.e., the refractive index of the electron blocking layer EBL-1 is greater than or less than the refractive index of the hole transport layer HTL-1, and is greater than or equal to the refractive index of the light-emitting layer EML-1); in the second light-emitting unit, the electron blocking layer EBL-2 is located between the hole transport layer HTL-2 and the light-emitting layer EML-2.
  • the electron blocking layer EBL-2 is the first low-refractive layer
  • the first adjacent layers on opposite sides thereof are respectively The hole transport layer HTL-2 and the light emitting layer EML-2 (ie, the refractive index of the electron blocking layer EBL-2 is greater than or less than the refractive index of the hole transport layer HTL-2, and greater than or equal to the refractive index of the light emitting layer EML-2).
  • the refractive index of the film layer adjacent thereto may also be greater than or equal to the refractive index of the hole transport layer, and the difference between the two may specifically be less than or equal to 0.5, for example, less than or equal to 0.4, less than or equal to 0.3, less than or equal to 0.2, less than or equal to 0.1, etc.
  • the difference between the two may be 0, 0.01, 0.03, 0.05, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 or a range consisting of any two of them.
  • the refractive index of the film layer adjacent thereto may also be greater than or equal to the refractive index of the hole transport layer, and the difference between the two may specifically be less than or equal to 0.5, for example, less than or equal to 0.4, less than or equal to 0.3, less than or equal to 0.2, less than or equal to 0.1, etc.
  • the difference between the two may be 0, 0.01, 0.03, 0.05, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 or a range consisting of any two of them.
  • the refractive index of each adjacent two of the hole injection layer HIL, the hole transport layer HTL-1, the electron blocking layer EBL-1 and the light-emitting layer EML-1 is different, for example, the difference in refractive index of each adjacent two is less than or equal to 0.5; in the second light-emitting unit, the hole transport layer HTL-2 is the first low-refractive layer, and the refractive index of each adjacent two of the hole transport layer HTL-2, the electron blocking layer EBL-2 and the light-emitting layer EML-2 is different, for example, the difference in refractive index of each adjacent two is less than or equal to 0.5.
  • the hole mobility of the hole transport layer closer to the first electrode is smaller, and the ratio of the hole mobility of two adjacent hole transport layers can be specifically 1.1 to 2, such as 1.1, 1.3, 1.5, 1.8, 2 or a range composed of any two of them, which can make up for the problem of insufficient electron generation capacity of the charge generation layer adjacent to the light-emitting unit closest to the first electrode, thereby improving the carrier balance and further improving the efficiency and other performance of the stacked device.
  • the two adjacent hole transport layers can both be the first low-refractive layers.
  • the hole transport layer HTL-1 of the first light-emitting unit The hole mobility is less than the hole mobility of the hole transport layer HTL-2 in the second light emitting unit, and the difference between the two can be 1.1 to 2, for example, 1.1, 1.3, 1.5, 1.8, 2 or a range consisting of any two thereof.
  • the hole mobility of the electron blocking layer closer to the first electrode is smaller, and the ratio of the hole mobility of two adjacent electron blocking layers can be specifically 1.1-2, such as 1.1, 1.3, 1.5, 1.8, 2 or a range composed of any two of them, which can make up for the problem of insufficient electron generation capacity of the charge generation layer adjacent to the light-emitting unit closest to the first electrode, thereby improving the carrier balance and further improving the efficiency and other performance of the stacked device.
  • the two adjacent electron blocking layers can both be first low-refractive layers.
  • the hole mobility of the electron blocking layer EBL-1 in the first light-emitting unit is less than the hole mobility of the electron blocking layer EBL-2 in the second light-emitting unit, and the difference between the two can be 1.1 to 2, for example, 1.1, 1.3, 1.5, 1.8, 2 or a range composed of any two of them.
  • the hole mobility is the space charge limited current hole mobility, which can be measured by conventional methods in the art.
  • the p-type charge generation layer includes a second host material and a second p-type doping material.
  • the at least one p-type charge generation layer is a second low-refractive layer, and the second low-refractive layer includes a second host material having a refractive index less than 1.8.
  • the refractive index n4 of the second host material with a refractive index less than 1.8 may be greater than 1.2.
  • the refractive index n4 of the second host material with a refractive index less than 1.8 is, for example, 1.25, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75 or a range consisting of any two of them.
  • the mass percentage of the second main material having a refractive index less than 1.8 is greater than or equal to 90%, for example, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97% or a range consisting of any two thereof.
  • the refractive index of the second low-refractive layer is substantially equal to the refractive index n 4 of the second main material therein, that is, the refractive index of the second low-refractive layer is less than 1.8, which is conducive to further improving the current efficiency and other performances of the stacked device.
  • the above-mentioned p-type charge generation layer may also include a second p-type doping material.
  • the mass percentage of the second p-type doping material is 3% to 10%, for example, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or a range composed of any two of them, which can further improve the performance of the stacked device.
  • the second p-type doping material when the p-type charge generation layer is the second low-refractive layer, the second p-type doping material
  • the content when the content is within the above range (3% to 10%), it basically does not affect the refractive index of the p-type charge generation layer, that is, the refractive index of the p-type charge generation layer is basically equal to the refractive index of the second main material therein, that is, the refractive index of the p-type charge generation layer is less than 1.8, which is beneficial to further improve the current efficiency and other performance of the stacked device.
  • the refractive index of the second host material with a refractive index less than 1.8 is n 4
  • the thickness of the second low-refractive layer is H 4
  • 6nm ⁇ n 4 ⁇ H 4 ⁇ 36nm is conducive to further improving the efficiency and other performance of the stacked device.
  • n 4 ⁇ H 4 may be a range consisting of any two of 6 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, and 36 nm.
  • the thickness H2 of the second low-refractive layer may be in the range of 5 nm to 20 nm, for example, 5 nm, 8 nm, 10 nm, 13 nm, 15 nm, 18 nm, 20 nm, or any two thereof.
  • the organic electroluminescent device includes a second adjacent layer adjacent to the second low-refractive layer, the second adjacent layer adjacent to the second low-refractive layer is in direct contact with the second low-refractive layer, there is no other film layer between the two, the refractive index of the second low-refractive layer is greater than or less than the refractive index of the second adjacent layer, and the difference between the refractive index of the second low-refractive layer and the refractive index of the second adjacent layer can be specifically less than or equal to 0.5, for example, less than or equal to 0.4, less than or equal to 0.3, less than or equal to 0.2, etc., so that the adverse effects such as interface reflection caused by the excessive refractive index of the second low-refractive layer and the second adjacent layer can be prevented, thereby further optimizing the microcavity effect and improving the current efficiency and other performance of the device.
  • the difference between the refractive index of the second low refractive layer and the refractive index of the second adjacent layer is 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 or a range consisting of any two thereof.
  • the second adjacent layer may include a hole transport layer and/or an n-type charge generation layer adjacent to the second low refractive layer, that is, the second adjacent layer may include a hole transport layer located on one side of the second low refractive layer and/or an n-type charge generation layer located on the other side of the second low refractive layer, the n-type charge generation layer is located on the side of the second low refractive layer facing the first electrode, and the hole transport layer is located on the side of the second low refractive layer facing the second electrode.
  • At least one charge generation layer further includes a metal layer between the n-type charge generation layer and the p-type charge generation layer, which can reduce the drive resistance of the stacked device.
  • the device can reduce the dynamic voltage and improve the stability of the device, which can be specifically manifested in that the voltage changes less during the operation of the device.
  • the metal layer may include metals from Group IIIA of the periodic table and/or transition metals, for example, one or more of aluminum, silver, gold, molybdenum, and titanium.
  • the hole transport region adjacent to the p-type charge generation layer of the charge generation layer including the metal layer includes a first low-refractive layer (that is, for the charge generation layer including the metal layer, the hole transport region adjacent to its p-type charge generation layer includes the first low-refractive layer), and the first low-refractive layer can be a hole transport layer and/or an electron blocking layer, etc. (taking the stacked device shown in Figure 2 as an example, the hole transport layer HTL-2 and/or the electron blocking layer EBL-2 in its second light-emitting unit is the first low-refractive layer), which can further improve the current efficiency and other performance of the stacked device.
  • the first electrode, hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, charge generation layer, second electrode and other film layers can be made of conventional materials in the field that meet the preset refractive index and other property requirements, without special restrictions.
  • the anode includes transparent conductive oxide materials such as indium tin oxide (or indium tin oxide, ie, ITO), indium zinc oxide (or indium zinc oxide, ie, IZO), tin dioxide (SnO 2 ), zinc oxide (ZnO), and any combination thereof.
  • transparent conductive oxide materials such as indium tin oxide (or indium tin oxide, ie, ITO), indium zinc oxide (or indium zinc oxide, ie, IZO), tin dioxide (SnO 2 ), zinc oxide (ZnO), and any combination thereof.
  • the cathode material can be metals or alloys such as magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), and any combination thereof.
  • the hole transport material may include an aromatic amine compound, specifically a triaromatic amine compound, such as HTM1 or NPB, etc.; the first p-type doping material may include NDP-9.
  • the hole transport material of the hole transport layer may include an aromatic amine compound, specifically a triarylamine compound, such as HTM1, HTM2, NPB, the hole transport material in patent document CN104718636B, the aromatic amine derivative shown in general formula (1-d) used in the hole transport layer in patent document US8394510B2 or CN101535256B (the specific structure of the aromatic amine derivative is detailed in US8394510B2 or CN101535256B, which will not be repeated here), etc., one or more, but not limited to these.
  • an aromatic amine compound specifically a triarylamine compound, such as HTM1, HTM2, NPB
  • the hole transport material in patent document CN104718636B the hole transport material in patent document CN104718636B
  • the aromatic amine derivative shown in general formula (1-d) used in the hole transport layer in patent document US8394510B2 or CN101535256B the specific structure of the aromatic amine derivative is detailed in US8394510B2 or CN101535
  • the hole transport material of the electron blocking layer may include an aromatic amine compound, specifically a triarylamine compound, such as BCzPh, an aromatic amine derivative as shown in the general formula (1-d) in patent document US8394510B2 or CN101535256B (for the specific structure of the aromatic amine derivative, please refer to US8394510B2 or CN101535256B, which will not be repeated here), etc., but is not limited to this.
  • an aromatic amine compound specifically a triarylamine compound, such as BCzPh
  • an aromatic amine derivative as shown in the general formula (1-d) in patent document US8394510B2 or CN101535256B for the specific structure of the aromatic amine derivative, please refer to US8394510B2 or CN101535256B, which will not be repeated here, etc., but is not limited to this.
  • the second main material in the p-type charge generation layer is a hole transport material, which may include an aromatic amine compound, specifically a triarylamine compound.
  • the second main material may include one or more of HTM1, NPB, the hole transport material in patent document CN104718636B, etc., but is not limited to this.
  • the second p-type doping material in the p-type charge generation layer may include NDP-9, but is not limited thereto.
  • the n-type charge generation layer includes a third host material and an n-type doping material.
  • the third host material includes, for example, B-Phen
  • the n-type doping material includes, for example, Li, but is not limited thereto.
  • the mass percentage of the n-type doping material can be 1% to 10%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or a range consisting of any two thereof.
  • the light-emitting layer may include a first host material and a guest material.
  • the light-emitting layer may be formed using conventional host materials and guest materials in the art.
  • the above-mentioned stacked device is a blue light device, and its light-emitting layer is a blue light-emitting layer.
  • the first host material may include ⁇ , ⁇ -AND, and the guest material may include t-DABNA, but is not limited thereto.
  • the mass percentage of the guest material can be 0.5% to 15%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or the range of any two thereof.
  • the mass percentage of the guest material therein can be 0.5% to 5%, such as 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or a range consisting of any two thereof.
  • the mass percentage of the guest material therein can be 1% to 15%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or a range consisting of any two thereof.
  • the electron transport region may include at least one of an electron injection layer, an electron transport layer and a hole blocking layer.
  • the electron transport region of one or at least two light-emitting units may include an electron injection layer, and generally the electron transport region of the light-emitting unit closest to the second electrode (the second light-emitting unit as shown in Figures 1 and 2) includes an electron injection layer;
  • the electron transport region of one or at least two light-emitting units may include an electron transport layer, and preferably the electron transport region of each light-emitting unit (such as the first light-emitting unit and the second light-emitting unit as shown in Figures 1 and 2) includes an electron transport layer respectively;
  • the electron transport region of one or at least two light-emitting units may include a hole blocking layer, and preferably the electron transport region of each light-emitting unit (such as the first light-emitting unit and the second light-emitting unit as shown in Figures 1 and 2) includes a hole
  • the electron transport region of the first light-emitting unit includes a hole blocking layer HBL-1 and an electron transport layer EIL-1 stacked in sequence from the first electrode to the second electrode
  • the electron transport region of the second light-emitting unit includes a hole blocking layer HBL-2, an electron transport layer EIL-2 and an electron injection layer HIL stacked in sequence from the first electrode to the second electrode.
  • the electron injection layer may include one or more of LiQ, LiF, NaCl, CsF, Li2O, Cs2CO3, BaO, Na, Li, Ca, Mg, and Yb, but is not limited thereto.
  • the electron transport layer may include an electron transport material and a doping material.
  • the electron transport material may include, for example, DppyA
  • the doping material may include, for example, one or more of LiQ, LiF, NaCl, CsF, Li2O, Cs2CO3 , BaO, Na, Li, Ca, Mg, Ag, and Yb, but is not limited thereto.
  • the mass percentage of the doping material in the electron transport layer, can be 30% to 70%, for example, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or a range consisting of any two thereof.
  • the electron blocking layer may include CzPhPy, but is not limited thereto.
  • the organic electroluminescent device may be a top-emitting device (top-emitting stacked device).
  • the organic electroluminescent device may further include a light extraction layer CPL disposed on the side of the second electrode away from the first electrode, so that the device's light color and efficiency and other performances can be further optimized.
  • the material of the light extraction layer CPL may be a conventional material of such layers in the art, but is not limited thereto.
  • the organic electroluminescent device includes a substrate, and the anode can be formed on the substrate by sputtering or depositing the anode material, and the remaining layers can be formed by conventional methods in the art such as vacuum thermal evaporation, spin coating, printing, etc., which will not be described in detail.
  • the substrate can be glass or polymer material with excellent mechanical strength, thermal stability, waterproofness, and transparency.
  • the substrate used as a display can also have a thin film transistor (TFT).
  • TFT thin film transistor
  • the display device of the embodiment of the present application includes the above-mentioned organic electroluminescent device.
  • the display device can be a display device such as an OLED display, and a television, a digital camera, Any product or component with display function, such as mobile phone, tablet computer, etc.
  • the display device has the same advantages as the above-mentioned organic electroluminescent device over the prior art, which will not be described in detail here.
  • the refractive index is the refractive index of light with a wavelength of about 460 nm.
  • the organic electroluminescent device of Example 1 is a top-emitting stacked device, and its structure is shown in FIG1 .
  • the properties of each film layer such as material and thickness are shown in Table 1.
  • Example 2 The difference from Example 1 is that the refractive index of the HIL and the p-CGL is less than 1.8, and the other conditions are the same as those of Example 1, as shown in Table 2 for details.
  • Example 3 and Example 4 The difference from Example 1 is that the hole mobility of HTL-1 and HTL-2 is different, as shown in Table 3. The other conditions are the same as those of Example 1.
  • Example 5 The difference from Example 1 is that a metal layer is provided between p-CGL and n-CGL (the structure of the stacked device is shown in FIG2 ), the material of the metal layer is Ag, and the thickness is 1 nm. The other conditions are the same as those of Example 1.
  • Comparative Example 1 The difference from Example 1 is that the refractive indexes of HIL, HTL-1, EBL-1, HTL-2 and EBL-2 are all greater than 1.8, as shown in Table 4. The other conditions are the same as those of Example 1.
  • the LT95 life test process is as follows: Use a brightness meter to maintain a constant current at an initial brightness of 1000cd/ m2 and measure the time it takes for the brightness of the organic electroluminescent device to drop to 950cd/ m2 , in hours (h).
  • the introduction of the first low-refractive layer into the hole transport region of the stacked devices of Examples 1 to 5 can improve the current efficiency and other performance of the device, while enabling the device to maintain a lower driving voltage (not higher than 6.6) and a higher lifespan (LT95 not less than 900h).
  • HTL-1 and HTL-2 of Example 1 use a hole transport material with a refractive index less than 1.8, which can improve the current efficiency and life of the device and reduce the driving voltage.
  • HTL-1, HTL-2, HIL and p-CGL of Example 2 respectively use hole transport materials with a refractive index less than 1.8, which can further improve the current efficiency of the device.
  • the hole mobility of HTL-1 in Example 4 is greater than that of HTL-2, and the performance of the device such as efficiency and life is worse than that of Example 1; relative to Example 1, the hole mobility of HTL-1 in Example 3 is less than that of HTL-2, and the current efficiency of the device is further improved. This shows that the closer the hole transport layer is to the anode, the smaller the hole mobility is, which can further improve the performance of the device such as the current efficiency.
  • Example 5 introduces a metal layer between the n-type charge generation layer and the p-type charge generation layer, which can further improve the current efficiency of the device and reduce the driving voltage.

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Abstract

本申请提供一种有机电致发光器件及显示装置，有机电致发光器件包括层叠设置的多个发光单元，每一所述发光单元包括依次层叠设置的空穴传输区、发光层和电子传输区，至少一所述发光单元的所述空穴传输区包括第一低折射层，所述第一低折射层包括折射率小于1.8的空穴传输材料。本申请能够提高叠层器件的电流效率等性能。

Description

有机电致发光器件及显示装置
本申请要求于2023年06月28日提交中国专利局、申请号为202310778705.5、申请名称为“有机电致发光器件及显示装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及显示技术领域，具体涉及一种有机电致发光器件及显示装置。
背景技术
有机发光二极管(Organic Light-Emitting Diode，OLED)是自发光器件，其具有轻薄、柔性、高对比度、宽色域等优点，其中，叠层器件具有多层堆叠设置的发光单元，其逐渐得到广泛关注和应用。然而，现有叠层器件的电流效率等性能有待进一步提高。
发明内容
本申请提供一种有机电致发光器件及显示装置，能够提高叠层器件的电流效率等性能，有效克服现有技术存在的缺陷。
本申请的一方面，提供一种有机电致发光器件，包括层叠设置的多个发光单元，每一所述发光单元包括依次层叠设置的空穴传输区、发光层和电子传输区，至少一所述发光单元的所述空穴传输区包括第一低折射层，所述第一低折射层包括折射率小于1.8的空穴传输材料。
本申请的另一方面，提供一种显示装置，包括上述有机电致发光器件。
本申请提供的有机电致发光器件中，使至少一个发光单元的空穴传输区包括第一低折射层，第一低折射层包括折射率小于1.8的空穴传输材料，能够有效提高叠层器件的电流效率，同时还可以使叠层器件兼具较低的驱动电压和较高的寿命等性能。
附图说明
图1为本申请一实施例的有机电致发光器件的结构示意图；
图2为本申请另一实施例的有机电致发光器件的结构示意图。
具体实施方式
为使本领域技术人员更好地理解本申请的方案，下面对本申请作进一步地详细说明。以下所列举具体实施方式只是对本申请的原理和特征进行描述，所举实例仅用于解释本申请，并非限定本申请的范围。基于本申请实施例，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方式，都属于本申请保护的范围。
叠层器件(叠层OLED(tandem OLED))具有多层堆叠设置的发光单元，通常在每相邻的两个发光单元之间设置电荷生成层(CGL)，以使电荷有效地分配到各发光单元，电荷生成层具有PN结，其包括依次堆叠的N型电荷生成层(N-CGL)和P型电荷生成层(P-CGL)。受限于叠层器件的结构以及其电荷生成层等膜层的电荷提供能力等因素，使得叠层器件的电流效率等性能较低。
举例来说，相对于单层OLED器件，叠层器件中的发光层更靠近电极，使得电极的表面等离子激元(SPP)淬灭作用较大，导致叠层器件具有较高的光学损耗，电流效率较低。
有鉴于此，本申请实施例提供一种有机电致发光器件，如图1和图2所示，该有机电致发光器件包括层叠设置的多个发光单元，每一发光单元包括依次层叠设置的空穴传输区、发光层和电子传输区，至少一发光单元的空穴传输区包括第一低折射层，第一低折射层包括折射率小于1.8的空穴传输材料。
本申请实施例的有机电致发光器件为叠层器件，在第一低折射层中引入折射率小于1.8的空穴传输材料，使其能够发挥空穴传输功能，与此同时，通过使至少一个发光单元包括该第一低折射层，能够有效提高叠层器件的电流效率，同时还可以使叠层器件兼具较低的驱动电压和较高的寿命等性能。
根据发明人的研究分析，使至少一发光单元的空穴传输区包括第一低折射层，即在至少一个发光单元的空穴传输区引入折射率小于1.8的空穴传输 材料，可以在保持微腔厚度的同时提高发光层与电极之间的距离，减弱电极的SPP作用(或称SPP淬灭作用)，进而降低叠层器件的光学损耗，提高其电流效率等性能。
具体地，上述发光层可以为红光发光层、绿光发光层或蓝光发光层，本申请实施例中，通过设置第一低折射层，可以提高红光叠层器件(发光层为红光发光层)、绿光叠层器件(发光层为绿光发光层)和蓝光叠层器件(发光层为蓝光发光层)的电流效率等性能，其中，相对而言，绿光发光层和蓝光发光层受电极SPP淬灭作用影响更为严重，因此，绿光叠层器件和蓝光叠层器件的电流效率更差，而本申请实施例可以显著提高绿光叠层器件和蓝光叠层器件的电流效率等性能。
具体地，上述折射率小于1.8的空穴传输材料的折射率可以大于1.2，示例性地，该折射率小于1.8的空穴传输材料的折射率例如为1.25、1.3、1.4、1.5、1.6、1.7、1.75或其中的任意两者组成的范围。
一般情况下，第一低折射层中，折射率小于1.8的空穴传输材料的质量百分含量大于或等于95％，例如为95％、95.5％、96％、96.5％、97％、97.5％、98％、98.5％、99％、99.5％、100％(如下述空穴传输层和电子阻挡层)或其中的任意两者组成的范围，第一低折射层的折射率基本等于其中的空穴传输材料的折射率，即第一低折射层的折射率小于1.8，利于进一步提高叠层器件的电流效率等性能。
本申请实施例中，所述的折射率均是指对波长为450nm～630nm的光的折射率。
具体地，如图1和图2所示，上述有机电致发光器件还包括与发光单元层叠设置的第一电极和第二电极，上述多个发光单元位于第一电极和第二电极之间、并沿第一电极至第二电极的方向依次层叠设置，第二电极与第一电极的极性相反，例如，第一电极为阳极，第二电极为阴极，每一发光单元中，其空穴传输区更靠近第一电极，电子传输区更靠近第二电极。
举例来说，上述发光单元的数量可以为两个(叠层器件为二阶微腔结构)、三个(叠层器件为三阶微腔结构)、四个(叠层器件为四阶微腔结构)等。以图1或图2所示的叠层器件为例，其发光单元的数量为两个，即分别为沿第一电极至第二电极的方向依次层叠设置的第一发光单元和第二发光单元，第 一发光单元包括发光层EML-1，第二发光单元包括发光层EML-2。
此外，如图1和图2所示，上述有机电致发光器件还可以包括位于每相邻的两个发光单元之间的电荷生成层，电荷生成层包括沿第一电极至第二电极的方向层叠设置的n型电荷生成层n-CGL和p型电荷生成层p-CGL，这样可以使电荷有效地分配到各发光单元中，提高各发光单元的电流效率。
通常，越靠近第一电极的发光单元，其发光层与第一电极的距离越近，第一电极对该发光单元产生的SPP淬灭作用越强，因此，一般优选最靠近第一电极的发光单元(如图1和图2所示的第一发光单元)的空穴传输区包括第一低折射层，这样可以更为显著地降低第一电极的SPP淬灭作用，进一步提高器件的电流效率等性能，其余发光单元(如图1和图2所示的第二发光单元)的空穴传输区可以包括或不包括第一低折射层(即空穴传输区的空穴传输材料的折射率不小于1.8)，优选这些发光单元的空穴传输区均分别包括第一低折射层(即上述多个发光单元(如图1和图2所示的第一发光单元和第二发光单元)的空穴传输区均分别包括第一低折射层)，这样可以进一步提高器件的电流效率等性能。
一般情况下，上述空穴传输区可以包括空穴注入层、空穴传输层和电子阻挡层中的一种或多种。上述多个发光单元中，可以是一个或至少两个发光单元的空穴传输区包括空穴注入层，一般最靠近第一电极的发光单元(如图1和图2所示的第一发光单元)的空穴传输区包括空穴注入层；可以是一个或至少两个发光单元的空穴传输区包括空穴传输层，优选每一发光单元(如图1和图2所示的第一发光单元和第二发光单元)的空穴传输区均分别包括空穴传输层；可以是一个或至少两个发光单元的空穴传输区包括电子阻挡层，优选每一发光单元(如图1和图2所示的第一发光单元和第二发光单元)的空穴传输区均分别包括电子阻挡层。
举例来说，如图1和图2所示，第一发光单元的空穴传输区包括沿第一电极至第二电极的方向依次层叠设置的空穴注入层HIL、空穴传输层HTL-1和电子阻挡层EBL-1，第二发光单元的空穴传输区包括沿第一电极至第二电极的方向层叠设置的空穴传输层HTL-2和电子阻挡层EBL-2。
上述空穴注入层、空穴传输层和电子阻挡层均分别包括空穴传输材料，第一低折射层可以为空穴注入层、空穴传输层和电子阻挡层中的至少一者， 即上述叠层器件的至少一个发光单元的空穴传输区包括空穴传输材料的折射率小于1.8的空穴注入层、空穴传输材料的折射率小于1.8的空穴传输层和空穴传输材料的折射率小于1.8的电子阻挡层中的至少一者。
在一些实施例中，最靠近第一电极的发光单元(如图1和图2所示的第一发光单元)的空穴传输区(即最靠近第一电极的空穴传输区)包括空穴注入层，该空穴注入层为第一低折射层，即该空穴注入层中的空穴传输材料的折射率n1小于1.8；和/或，最靠近第一电极的空穴传输区包括空穴传输层，该空穴传输层为第一低折射层，即该空穴传输层中的空穴传输材料的折射率n2小于1.8；和/或，最靠近第一电极的空穴传输区包括电子阻挡层，该电子阻挡层为第一低折射层，即该电子阻挡层中的空穴传输材料的折射率n3小于1.8。由此，使得最靠近第一电极的发光单元的空穴传输区包括第一低折射层。
在一些具体实施例中，在图1和图2所示的叠层器件中，其第一发光单元的空穴传输区中的空穴注入层HIL、空穴传输层HTL-1和电子阻挡层EBL-1中的至少一者为第一低折射层，使得最靠近第一电极的发光单元的空穴传输区包括第一低折射层。
在一些优选实施例中，每一发光单元的空穴传输区的空穴传输层均分别为第一低折射层，即每一发光单元的空穴传输层中的空穴传输材料的折射率n2均分别小于1.8，这样利于进一步提高叠层器件的电流效率等性能。其中，这些空穴传输层的空穴传输材料的折射率具体可以相等或不相等(如图1和图2所示的叠层器件中，其第一发光单元中的空穴传输层HTL-1的空穴传输材料的折射率可以等于或不等于第二发光单元中的空穴传输层HTL-2的空穴传输材料的折射率)。
在一些优选实施例中，每一发光单元的空穴传输区的电子阻挡层均分别为第一低折射层，即每一发光单元的电子阻挡层中的空穴传输材料的折射率n3均分别小于1.8，这样利于进一步提高叠层器件的发光效率等性能。其中，这些电子阻挡层的空穴传输材料的折射率具体可以相等或不相等(如图1和图2所示的叠层器件中，其第一发光单元中的电子阻挡层EBL-1的空穴传输材料的折射率可以等于或不等于第二发光单元中的电子阻挡层EBL-2的空穴传输材料的折射率)。
在一些实施例中，第一低折射层为空穴注入层，该第一低折射层(空穴传输材料的折射率小于1.8的空穴注入层)中，折射率小于1.8的空穴传输材料的折射率为n1(即n1＜1.8)，该第一低折射层的厚度为H1，6nm＜n1×H1＜54nm，亦即，当叠层器件的至少一个发光单元的空穴传输区包括空穴传输材料的折射率小于1.8的空穴注入层时，该空穴注入层的厚度H1和空穴传输材料的折射率n1满足6nm＜n1×H1＜54nm，这样利于进一步提高叠层器件的效率等性能，根据发明人的研究分析，控制n1与H1的层乘积(即n1×H1)在上述范围内，可以使空穴注入层具有更为适宜的光学厚度等性质，从而进一步优化叠层器件性能。
示例性地，n1×H1可以为7nm、10nm、15nm、20nm、25nm、30nm、35nm、40nm、45nm、50nm、53nm或其中的任意两者组成的范围。
示例性地，空穴传输材料的折射率小于1.8的空穴注入层中，其空穴传输材料的折射率n1例如为1.25、1.3、1.4、1.5、1.6、1.7、1.75或其中的任意两者组成的范围。
此外，空穴传输材料的折射率小于1.8的空穴注入层的厚度H1可以为5nm～30nm，例如5nm、10nm、15nm、20nm、25nm、30nm或其中的任意两者组成的范围。
以图1或图2所示的叠层器件为例，当其第一发光单元中的空穴注入层HIL为第一低折射层时，其中的空穴传输材料的折射率n1＜1.8，该空穴注入层HIL的厚度为H1可以为5nm～30nm，并可以满足6nm＜n1×H1＜54nm。
在一些实施例中，第一低折射层为空穴传输层，该第一低折射层(空穴传输材料的折射率小于1.8的空穴传输层)中，折射率小于1.8的空穴传输材料的折射率为n2(即n2＜1.8)，该第一低折射层的厚度为H2，6nm＜n2×H2＜360nm，亦即，当叠层器件的至少一个发光单元的空穴传输区包括空穴传输材料的折射率小于1.8的空穴传输层时，该空穴传输层的厚度H2和空穴传输材料的折射率n2满足6nm＜n2×H2＜360nm，这样利于进一步提高叠层器件的效率等性能，根据发明人的研究分析，控制n2与H2的层乘积(即n2×H2)在上述范围内，可以使空穴传输层具有更为适宜的光学厚度等性质，从而进一步优化叠层器件性能。
示例性地，n2×H2可以为7nm、10nm、30nm、50nm、70nm、100nm、130nm、150nm、180nm、200nm、230nm、250nm、280nm、300nm、330nm、355nm或其中的任意两者组成的范围。
示例性地，空穴传输材料的折射率小于1.8的空穴传输层中，其空穴传输材料的折射率n2例如为1.25、1.3、1.4、1.5、1.6、1.7、1.75或其中的任意两者组成的范围。
此外，空穴传输材料的折射率小于1.8的空穴传输层的厚度H2可以为5nm～200nm，例如5nm、30nm、50nm、80nm、100nm、130nm、150nm、180nm、200nm或其中的任意两者组成的范围。
以图1或图2所示的叠层器件为例，可以是其第一发光单元的空穴传输层HTL-1为第一低折射层，此时，第一发光单元的空穴传输层HTL-1的空穴传输材料的折射率n2＜1.8，该空穴传输层HTL-1的厚度H2可以为5nm～200nm，并可以满足6nm＜n2×H2＜360nm；或者第二发光单元的空穴传输层HTL-2为第一低折射层，此时，第二发光单元的空穴传输层HTL-2的空穴传输材料的折射率n2＜1.8，该空穴传输层HTL-2的厚度H2可以为5nm～200nm，并可以满足6nm＜n2×H2＜360nm；或者第一发光单元的空穴传输层HTL-1和第二发光单元的空穴传输层HTL-2均分别为第一低折射层，此时，第一发光单元的空穴传输层HTL-1和第二发光单元的空穴传输层HTL-2可以均分别满足：空穴传输材料的折射率n2＜1.8，空穴传输层的厚度H2可以为5nm～200nm，6nm＜n2×H2＜360nm。
在一些实施例中，第一低折射层为电子阻挡层，该第一低折射层(空穴传输材料的折射率小于1.8的电子阻挡层)中，折射率小于1.8的空穴传输材料的折射率为n3(即n3＜1.8)，该第一低折射层的厚度为H3，6nm＜n3×H3＜54nm，亦即，当叠层器件的至少一个发光单元的空穴传输区包括空穴传输材料的折射率小于1.8的电子阻挡层时，该电子阻挡层的厚度H3和空穴传输材料的折射率n3满足6nm＜n3×H3＜54nm，这样利于进一步提高叠层器件的效率等性能，根据发明人的研究分析，控制n3与H3的层乘积(即n3×H3)在上述范围内，可以使电子阻挡层具有更为适宜的光学厚度等性质，从而进一步优化叠层器件性能。
示例性地，n3×H3可以为7nm、10nm、15nm、20nm、25nm、30nm、 35nm、40nm、45nm、50nm、53nm或其中的任意两者组成的范围。
示例性地，空穴传输材料的折射率小于1.8的电子阻挡层中，其空穴传输材料的折射率n3例如为1.25、1.3、1.4、1.5、1.6、1.7、1.75或其中的任意两者组成的范围。
此外，空穴传输材料的折射率小于1.8的电子阻挡层的厚度H3可以为3nm～50nm，例如3nm、5nm、10nm、15nm、20nm、25nm、30nm、35nm、40nm、45nm、50nm或其中的任意两者组成的范围。
以图1或图2所示的叠层器件为例，可以是其第一发光单元的电子阻挡层EBL-1为第一低折射层，此时，第一发光单元的电子阻挡层EBL-1的空穴传输材料的折射率n3＜1.8，该电子阻挡层EBL-1的厚度H3可以为3nm～50nm，并可以满足6nm＜n3×H3＜54nm；或者第二发光单元的电子阻挡层EBL-2为第一低折射层，此时，第二发光单元的电子阻挡层EBL-2的空穴传输材料的折射率n2＜1.8，该电子阻挡层EBL-2的厚度H2可以为3nm～50nm，并可以满足6nm＜n3×H3＜54nm；或者第一发光单元的电子阻挡层EBL-1和第二发光单元的电子阻挡层EBL-2均分别为第一低折射层，此时，第一发光单元的电子阻挡层EBL-1和第二发光单元的电子阻挡层EBL-2可以均分别满足：空穴传输材料的折射率n3＜1.8，电子阻挡层的厚度H3可以为3nm～50nm，6nm＜n3×H3＜54nm。
具体地，空穴注入层、空穴传输层和电子阻挡层中的空穴传输材料的质量百分含量可以各自独立地大于或等于95％，例如，空穴传输层中的空穴传输材料的质量百分含量为100％(即空穴传输层全部由空穴传输材料形成)，电子阻挡层中的空穴传输材料的质量百分含量为100％(即电子阻挡层全部由空穴传输材料形成)，这些层的折射率或空穴迁移率与其所包括的空穴传输材料基本一致。
在一些实施例中，上述空穴注入层可以包括第一p型掺杂材料，空穴注入层中，第一p型掺杂材料的质量百分含量可以为0.5％～5％，例如0.5％、1％、1.5％、2％、2.5％、3％、3.5％、4％、4.5％、5％或其中的任意两者组成的范围，这样可以提高空穴注入层的空穴传输能力，进一步优化叠层器件的性能。
此外，当第一低折射层为空穴注入层时，第一p型掺杂材料的含量在 上述范围(0.5％～5％)内，基本不影响该空穴注入层(空穴传输材料的折射率小于1.8的空穴注入层)的折射率，即该空穴注入层的折射率基本等于其中的空穴传输材料的折射率，亦即该空穴注入层的折射率小于1.8，这样利于进一步提高叠层器件的电流效率等性能。
此外，上述有机电致发光器件还包括与第一低折射层相邻的第一相邻层，与第一低折射层相邻的第一相邻层和该第一低折射层直接接触，二者之间没有其他膜层，第一低折射层的折射率大于或小于第一相邻层的折射率，第一低折射层的折射率与第一相邻层的折射率的差值具体可以小于或等于0.5，例如小于或等于0.4、小于或等于0.3、小于或等于0.2、小于或等于0.1等，这样可以防止第一低折射层与第一相邻层的折射率过大而导致的界面反射等不利影响，从而进一步优化微腔效果，提高器件的电流效率等性能。
示例性地，第一低折射层的折射率与第一相邻层的折射率的差值为0、0.01、0.03、0.05、0.07、0.08、0.1、0.15、0.2、0.25、0.3、0.35、0.4、0.45、0.5或其中的任意两者组成的范围。
其中，第一相邻层可以位于第一低折射层的一侧(如位于第一低折射层面向第一电极的一侧、或者位于第一低折射层面向第二电极的一侧)，或者，也可以位于第一低折射层的相对两侧(即第一低折射层的相对两侧的膜层的折射率均分别与第一低折射层的折射率不同，例如第一低折射层的相对两侧的膜层的折射率均分别与第一低折射层的折射率的差值小于或等于0.5，该相对两侧分别为第一低折射层面向第一电极的一侧和第一低折射层面向第二电极的一侧)。
在一些实施例中，第一低折射层为空穴注入层，第一相邻层可以为空穴传输层。举例来说，如图1和图2所示的第一发光单元的空穴传输区中，其空穴注入层HIL为第一低折射层，此时，该空穴注入层HIL的第一相邻层为空穴传输层HTL-1(即空穴注入层HIL的折射率大于或小于空穴传输层HTL-1的折射率)。
在一些实施例中，第一低折射层为空穴传输层，第一相邻层包括与第一低折射层的一侧(面向第一电极的一侧)相邻的空穴注入层、以及与第一低折射层的另一侧(面向第二电极的一侧)相邻的电子阻挡层或发光层。
当空穴传输区包括依次层叠设置的空穴注入层、空穴传输层和电子阻挡层、且空穴传输层为第一低折射层时，该空穴传输层的相对两侧的第一相邻层分别为空穴注入层和电子阻挡层(即空穴传输层的折射率大于或小于空穴注入层的折射率、且大于或等于电子阻挡层的折射率)。以如图1和图2所示的第一发光单元的空穴传输区为例，当其空穴传输层HTL-1为第一低折射层时，第一相邻层包括空穴注入层HIL和电子阻挡层EBL-1。
当空穴传输区由层叠设置的空穴注入层和空穴传输层组成(未设置电子阻挡层)、且空穴传输层为第一低折射层时，该空穴传输层位于空穴注入层和发光层之间，其相对两侧的第一相邻层分别为空穴注入层和发光层(即空穴传输层的折射率大于或小于空穴注入层的折射率、且大于或等于与其相邻的发光层的折射率)。
在其他实施例中，叠层器件中的某一个或某几个发光单元的空穴传输区也可以不包括空穴注入层(如图1和图2所示的第二发光单元的空穴传输区)，这些空穴传输区例如仅设置有空穴传输层，当该空穴传输层为第一低折射层时，其第一相邻层为与其相邻的发光层；或者，这些空穴传输区包括空穴传输层和电子阻挡层，当空穴传输层为第一低折射层时，其第一相邻层包括与其一侧相邻的p型电荷生成层、以及与其另一侧相邻的电子阻挡层，p型电荷生成层和电子阻挡层分别位于该空穴传输层的相对两侧。以如图1和图2所示的第二发光单元的空穴传输区为例，当其空穴传输层HTL-2为第一低折射层时，第一相邻层包括p型电荷生成层p-CGL和电子阻挡层EBL-2。
在一些实施例中，第一低折射层为电子阻挡层，第一相邻层包括与第一低折射层的一侧相邻的空穴传输层、以及与第一低折射层的另一侧相邻的发光层。举例来说，如图1和图2所示，第一发光单元中，电子阻挡层EBL-1位于空穴传输层HTL-1和发光层EML-1之间，当电子阻挡层EBL-1为第一低折射层时，其相对两侧的第一相邻层分别为空穴传输层HTL-1和发光层EML-1(即电子阻挡层EBL-1的折射率大于或小于空穴传输层HTL-1的折射率、且大于或等于与发光层EML-1的折射率)；第二发光单元中，电子阻挡层EBL-2位于空穴传输层HTL-2和发光层EML-2之间，当电子阻挡层EBL-2为第一低折射层时，其相对两侧的第一相邻层分别为 空穴传输层HTL-2和发光层EML-2(即电子阻挡层EBL-2的折射率大于或小于空穴传输层HTL-2的折射率、且大于或等于与发光层EML-2的折射率)。
此外，当某一或某些空穴传输层不是第一低折射层(即该空穴传输层中的空穴传输材料的折射率不小于1.8)时，与其相邻的膜层(如空穴注入层、电子阻挡层或发光层)的折射率也可以大于或等于该空穴传输层的折射率，二者的差值具体可以小于或等于0.5，例如小于或等于0.4、小于或等于0.3、小于或等于0.2、小于或等于0.1等，举例来说，二者的差值可以为0、0.01、0.03、0.05、0.07、0.08、0.1、0.15、0.2、0.25、0.3、0.35、0.4、0.45、0.5或其中的任意两者组成的范围。
此外，当某一或某些电子阻挡层不是第一低折射层(即该空穴传输层中的空穴传输材料的折射率不小于1.8)时，与其相邻的膜层(如空穴传输层或发光层)的折射率也可以大于或等于该空穴传输层的折射率，二者的差值具体可以小于或等于0.5，例如小于或等于0.4、小于或等于0.3、小于或等于0.2、小于或等于0.1等，举例来说，二者的差值可以为0、0.01、0.03、0.05、0.07、0.08、0.1、0.15、0.2、0.25、0.3、0.35、0.4、0.45、0.5或其中的任意两者组成的范围。
在一些具体实施例中，在如图1所示的叠层器件中，第一发光单元中，空穴注入层HIL、空穴传输层HTL-1、电子阻挡层EBL-1和发光层EML-1中的每相邻的两者的折射率均不同，例如，每相邻的两者的折射率的差值均小于或等于0.5；第二发光单元中，空穴传输层HTL-2为第一低折射层，空穴传输层HTL-2、电子阻挡层EBL-2和发光层EML-2中的每相邻的两者的折射率均不同，例如，每相邻的两者的折射率的差值均小于或等于0.5。
此外，上述叠层器件中，越靠近第一电极的空穴传输层的空穴迁移率越小，相邻两个空穴传输层的空穴迁移率的比值具体可以为1.1～2，例如1.1、1.3、1.5、1.8、2或其中的任意两者组成的范围，这样可以弥补最靠近第一电极的发光单元相邻的电荷生成层的电子产生能力不足等问题，从而提高载流子平衡，进一步提高叠层器件的效率等性能。其中，该相邻两个空穴传输层可以均分别为第一低折射层。
举例来说，如图1和图2所示，第一发光单元的空穴传输层HTL-1的 空穴迁移率小于第二发光单元中的空穴传输层HTL-2的空穴迁移率，二者的差值可以为1.1～2，例如1.1、1.3、1.5、1.8、2或其中的任意两者组成的范围。
此外，越靠近第一电极的电子阻挡层的空穴迁移率越小，相邻两个电子阻挡层的空穴迁移率的比值具体可以为1.1-2，例如1.1、1.3、1.5、1.8、2或其中的任意两者组成的范围，这样可以弥补最靠近第一电极的发光单元相邻的电荷生成层的电子产生能力不足等问题，从而提高载流子平衡，进一步提高叠层器件的效率等性能。其中，该相邻两个电子阻挡层可以均分别为第一低折射层。
举例来说，如图1所示，第一发光单元的电子阻挡层EBL-1的空穴迁移率小于第二发光单元中的电子阻挡层EBL-2的空穴迁移率，二者的差值可以为1.1～2，例如1.1、1.3、1.5、1.8、2或其中的任意两者组成的范围。
一般情况下，所述的空穴迁移率为空间电荷限制电流空穴迁移率，其可以通过本领域常规方法测得。
具体地，上述p型电荷生成层包括第二主体材料和第二p型掺杂材料。
在一些实施例中，至少一p型电荷生成层为第二低折射层，第二低折射层包括折射率小于1.8的第二主体材料。
具体地，上述折射率小于1.8的第二主体材料的折射率n4可以大于1.2，示例性地，该折射率小于1.8的第二主体材料的折射率n4例如为1.25、1.3、1.4、1.5、1.6、1.7、1.75或其中的任意两者组成的范围。
一般情况下，第二低折射层中，折射率小于1.8的第二主体材料的质量百分含量大于或等于90％，例如为90％、91％、92％、93％、94％、95％、96％、97％或其中的任意两者组成的范围，第二低折射层的折射率基本等于其中的第二主体材料的折射率n4，即第二低折射层的折射率小于1.8，利于进一步提高叠层器件的电流效率等性能。
具体地，上述p型电荷生成层还可以包括第二p型掺杂材料，p型电荷生成层中，第二p型掺杂材料的质量百分含量为3％～10％，例如3％、4％、5％、6％、7％、8％、9％、10％或其中的任意两者组成的范围，这样可以进一步提高叠层器件的性能。
此外，当p型电荷生成层为第二低折射层时，其第二p型掺杂材料的 含量在上述范围(3％～10％)内，基本不影响该p型电荷生成层的折射率，即该p型电荷生成层的折射率基本等于其中的第二主体材料的折射率，亦即该p型电荷生成层的折射率小于1.8，这样利于进一步提高叠层器件的电流效率等性能。
在一些实施例中，折射率小于1.8的第二主体材料的折射率为n4，第二低折射层的厚度为H4，6nm＜n4×H4＜36nm，这样利于进一步提高叠层器件的效率等性能，根据发明人的研究分析，控制n4与H4的层乘积(即n4×H4)在上述范围内，可以使p型电荷生成层具有更为适宜的光学厚度等性质，从而进一步优化叠层器件性能。
示例性地，n4×H4可以为6nm、10nm、15nm、20nm、25nm、30nm、36nm其中的任意两者组成的范围。
此外，第二低折射层的厚度H2可以为5nm～20nm，例如5nm、8nm、10nm、13nm、15nm、18nm、20nm或其中的任意两者组成的范围。
在一些实施例中，上述有机电致发光器件包括与第二低折射层相邻的第二相邻层，与第二低折射层相邻的第二相邻层和该第二低折射层直接接触，二者之间没有其他膜层，第二低折射层的折射率大于或小于第二相邻层的折射率，第二低折射层的折射率与第二相邻层的折射率的差值具体可以小于或等于0.5，例如小于或等于0.4、小于或等于0.3、小于或等于0.2等，这样可以防止第二低折射层与第二相邻层的折射率过大而导致的界面反射等不利影响，从而进一步优化微腔效果，提高器件的电流效率等性能。
示例性地，第二低折射层的折射率与第二相邻层的折射率的差值为0.05、0.1、0.15、0.2、0.25、0.3、0.35、0.4、0.45、0.5或其中的任意两者组成的范围。
具体地，第二相邻层可以包括与第二低折射层相邻的空穴传输层和/或n型电荷生成层，即第二相邻层可以包括位于第二低折射层的一侧的空穴传输层和/或位于第二低折射层的另一侧的n型电荷生成层，n型电荷生成层位于第二低折射层面向第一电极的一侧，空穴传输层位于第二低折射层面向第二电极的一侧。
此外，在一些实施例中，如图2所示，至少一电荷生成层还包括位于n型电荷生成层与p型电荷生成层之间的金属层，这样可以降低叠层器件的驱 动电压，并提高器件的稳定性，具体可表现在，在器件的工作过程中其电压变化程度更小。
具体地，上述金属层可以包括元素周期表第IIIA族金属和/或过渡金属，例如包括铝、银、金、钼、钛中的一种或多种。
在一些实施例中，与包括金属层的电荷生成层的p型电荷生成层相邻的空穴传输区(如图2中的第二发光单元的空穴传输区)包括第一低折射层(即对于包括金属层的电荷生成层，其p型电荷生成层邻接的空穴传输区包括第一低折射层)，该第一低折射层可以是空穴传输层和/或电子阻挡层等(以图2所示的叠层器件为例，其第二发光单元中的空穴传输层HTL-2和/或电子阻挡层EBL-2为第一低折射层)，这样可以进一步提高叠层器件的电流效率等性能。
上述器件中，第一电极、空穴注入层、空穴传输层、电子阻挡层、发光层、电荷生成层、第二电极等膜层可采用符合预设折射率等性质要求的本领域常规材料，对此不作特别限制。
示例性地，阳极包括铟锡氧化物(或称氧化铟锡，即ITO)、铟锌氧化物(或称氧化铟锌，即IZO)、二氧化锡(SnO2)、氧化锌(ZnO)等氧化物透明导电材料和它们的任意组合。
示例性地，阴极材料可以采用镁(Mg)、银(Ag)、铝(Al)、铝-锂(Al-Li)、钙(Ca)、镁-铟(Mg-In)、镁-银(Mg-Ag)等金属或合金以及它们之间的任意组合。
示例性地，空穴注入层中，空穴传输材料可以包括芳胺化合物，具体可以包括三芳胺化合物，例如包括HTM1或NPB等；第一p型掺杂材料可以包括NDP-9。
示例性地，空穴传输层的空穴传输材料可以包括芳胺化合物，具体可以包括三芳胺类化合物，例如包括HTM1、HTM2、NPB、专利文献CN104718636B中的空穴传输材料、专利文献US8394510B2或CN101535256B中空穴输送层所用的如通式(1-d)所示的芳香族胺衍生物(该芳香胺衍生物的具体结构详见US8394510B2或CN101535256B，不再赘述)等中的一种或多种，但不局限于此。
示例性地，电子阻挡层的空穴传输材料可以包括芳胺化合物，具体可以包括三芳胺类化合物，例如包括BCzPh、专利文献US8394510B2或CN101535256B中的如通式(1-d)所示的芳香族胺衍生物(关于该芳香胺衍生物的具体结构详见US8394510B2或CN101535256B，不再赘述)等中的一种或多种，但不局限于此。
此外，p型电荷生成层中的第二主体材料为空穴传输材料，其可以包括芳胺化合物，具体可以包括三芳胺化合物，例如，第二主体材料可以包括HTM1、NPB、专利文献CN104718636B中的空穴传输材料等中的一种或几种，但不局限于此。
示例性地，p型电荷生成层中的第二p型掺杂材料可以包括NDP-9，但不局限于此。
此外，n型电荷生成层包括第三主体材料和n型掺杂材料，第三主体材料例如包括B-Phen，n型掺杂材料例如包括Li，但不局限于此。
在一些实施例中，n型电荷生成层中，n型掺杂材料的质量百分含量可以为1％～10％，例如1％、2％、3％、4％、5％、6％、7％、8％、9％、10％或其中的任意两者组成的范围。
此外，发光层可以包括第一主体材料和客体材料，可采用本领域常规主体材料和客体材料形成发光层，举例来说，上述叠层器件为蓝光器件，其发光层为蓝光发光层，第一主体材料例如包括α,β-AND，客体材料例如包括t-DABNA，但不局限于此。
具体地，上述发光层中，客体材料的质量百分含量可以为0.5％～15％，例如0.5％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％、11％、12％、13％、14％、15％或其中的任意两者组成的范围。
一般情况下，当上述发光层为蓝光发光层或红光发光层时，其中的客体材料的质量百分含量可以为0.5％～5％，例如0.5％、1％、1.5％、2％、2.5％、3％、3.5％、4％、4.5％、5％或其中的任意两者组成的范围。当上述发光层为绿光发光层时，其中的客体材料的质量百分含量可以为1％～15％，例如1％、2％、3％、4％、5％、6％、7％、8％、9％、10％、11％、12％、13％、14％、15％或其中的任意两者组成的范围。
此外，电子传输区可以包括电子注入层、电子传输层和空穴阻挡层中的至少一者。上述多个发光单元中，可以是一个或至少两个发光单元的电子传输区包括电子注入层，一般最靠近第二电极的发光单元(如图1和图2所示的第二发光单元)的电子传输区包括电子注入层；可以是一个或至少两个发光单元的电子传输区包括电子传输层，优选每一发光单元(如图1和图2所示的第一发光单元和第二发光单元)的电子传输区均分别包括电子传输层；可以是一个或至少两个发光单元的电子传输区包括空穴阻挡层，优选每一发光单元(如图1和图2所示的第一发光单元和第二发光单元)的电子传输区均分别包括空穴阻挡层。
举例来说，如图1和图2所示，第一发光单元的电子传输区包括沿第一电极至第二电极的方向依次层叠设置的空穴阻挡层HBL-1和电子传输层EIL-1，第二发光单元的电子传输区包括沿第一电极至第二电极的方向依次层叠设置的空穴阻挡层HBL-2、电子传输层EIL-2和电子注入层HIL。
示例性地，电子注入层可以包括LiQ、LiF、NaCl、CsF、Li2O、Cs2CO3、BaO、Na、Li、Ca、Mg、Yb中的一种或多种，但不局限于此。
此外，电子传输层可以包括电子传输材料和掺杂材料，电子传输材料例如包括DppyA，掺杂材料例如包括LiQ、LiF、NaCl、CsF、Li2O、Cs2CO3、BaO、Na、Li、Ca、Mg、Ag、Yb中的一种或多种，但不局限于此。
在一些实施例中，电子传输层中，掺杂材料的质量百分含量可以为30％～70％，例如30％、35％、40％、45％、50％、55％、60％、65％、70％或其中的任意两者组成的范围。
示例性地，电子阻挡层可以包括CzPhPy，但不局限于此。
具体地，上述有机电致发光器件可以为顶发射器件(顶发射叠层器件)。
在一些实施例中，如图1和图2所示，上述有机电致发光器件还可以包括设于第二电极背离第一电极的一侧的光取出层CPL，这样可以进一步优化器件的光色和效率等性能。光取出层CPL的材料可以是本领域这类层的常规材料，但不局限于此。
一般情况下，上述有机电致发光器件包括基板，阳极可以通过溅射或沉积阳极材料的方式形成于基板上，其余层可通过真空热蒸镀、旋转涂覆、打印等本领域常规方式形成，不再赘述。其中，基板可以为具有机械强度、热稳定性、防水性、透明度优异的玻璃或聚合物材料，此外，作为显示器用的基板上也可以带有薄膜晶体管(TFT)。
本申请实施例的显示装置包括上述有机电致发光器件。该显示装置具体可以为OLED显示器等显示器件，以及包括该显示器件的电视、数码相机、 手机、平板电脑等任何具有显示功能的产品或者部件。该显示装置与上述有机电致发光器件相对于现有技术所具有的优势相同，在此不再赘述。
以下通过具体实施例对本申请的有机电致发光器件进行进一步的介绍。以下实施例和对比例中，所述的折射率是对波长为460nm左右的光的折射率。
实施例1
本实施例1的有机电致发光器件为顶发射叠层器件，其结构如图1所示，各膜层材料和厚度等性质见表1。
表1
实施例2：与实施例1的区别在于，HIL和p-CGL的折射率小于1.8，其余条件与实施例1相同，具体见表2。
表2
实施例3和实施例4：与实施例1的区别在于，HTL-1、HTL-2的空穴迁移率不同，具体见表3，其余条件与实施例1相同。
表3
实施例5：与实施例1的区别在于，p-CGL与n-CGL之间设有金属层(叠层器件的结构如图2所示)，该金属层的材料为Ag，厚度为1nm，其余条件与实施例1相同。
对比例1：与实施例1的区别在于，HIL、HTL-1、EBL-1、HTL-2、EBL-2的折射率均大于1.8，具体见表4，其余条件与实施例1相同。
表4
测得各实施例和对比例的器件的电压(点亮时的驱动电压)、电流效率(器件达到亮度1050nits时的电流效率)、LT95寿命，结果见表5。
其中，LT95寿命测试过程如下：使用亮度计在初始1000cd/m2亮度下，保持恒定的电流，测量有机电致发光器件的亮度降为950cd/m2的时间，单位为小时(h)。
表5
可以看到，相对于对比例1，实施例1～实施例5的叠层器件的空穴传输区引入第一低折射层，能够提高器件的电流效率等性能，同时使器件保持较低的驱动电压(不高于6.6)和较高的寿命(LT95不低于900h)。
具体地，相对于对比例1，实施例1的HTL-1、HTL-2采用折射率小于1.8的空穴传输材料，能够提高器件的电流效率和寿命，并降低驱动电压。
具体地，相对于实施例1，实施例2的HTL-1、HTL-2、HIL和p-CGL均分别采用折射率小于1.8的空穴传输材料，能够进一步提高器件的电流效率。
具体地，相对于实施例1，实施例4的HTL-1的空穴迁移率大于HTL-2的空穴迁移率，器件的效率和寿命等性能差于实施例1；相对于实施例1，实施例3的HTL-1的空穴迁移率小于HTL-2的空穴迁移率，器件的电流效率进一步提高。由此表明，越靠近阳极的空穴传输层的空穴迁移率越小，能够进一步提高器件的电流效率等性能。
具体地，相对于实施例1，实施例5在n型电荷生成层与p型电荷生成层之间引入金属层，能够进一步提高器件的电流效率，并降低驱动电压。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围。

Claims (20)

  1. 一种有机电致发光器件，其中，包括层叠设置的多个发光单元，每一所述发光单元包括依次层叠设置的空穴传输区、发光层和电子传输区，至少一所述发光单元的所述空穴传输区包括第一低折射层，所述第一低折射层包括折射率小于1.8的空穴传输材料。
  2. 根据权利要求1所述的有机电致发光器件，其中，
    所述折射率小于1.8的空穴传输材料的折射率大于1.2；
    和/或，所述第一低折射层中，所述折射率小于1.8的空穴传输材料的质量百分含量大于或等于95％。
  3. 根据权利要求1所述的有机电致发光器件，其中，还包括与所述发光单元层叠设置的第一电极，所述多个发光单元中，最靠近所述第一电极的所述发光单元的所述空穴传输区包括所述第一低折射层。
  4. 根据权利要求3所述的有机电致发光器件，其中，
    所述第一电极为阳极；
    和/或，所述多个发光单元的所述空穴传输区均分别包括所述第一低折射层。
  5. 根据权利要求1所述的有机电致发光器件，其中，所述发光层为红光发光层、绿光发光层或蓝光发光层。
  6. 根据权利要求1所述的有机电致发光器件，其中，所述空穴传输区包括空穴注入层、空穴传输层和电子阻挡层中的一种或多种，所述第一低折射层为所述空穴注入层、空穴传输层和电子阻挡层中的至少一者。
  7. 根据权利要求6所述的有机电致发光器件，其中，
    所述空穴注入层还包括第一p型掺杂材料，所述空穴注入层中，所述第一p型掺杂材料的质量百分含量为0.5％～5％；
    和/或，所述第一低折射层为所述空穴注入层，其中，所述第一低折射层的厚度为5nm～30nm，和/或，所述折射率小于1.8的空穴传输材料的折射率为n1，所述第一低折射层的厚度为H1，6nm＜n1×H1＜54nm；
    和/或，所述第一低折射层为所述空穴传输层，其中，所述第一低折射层的厚度为5nm～200nm，和/或，所述折射率小于1.8的空穴传输材料的折射率为n2，所述第一低折射层的厚度为H2，6nm＜n2×H2＜360nm；
    和/或，所述第一低折射层为所述电子阻挡层，其中，所述第一低折射层的厚度为3nm～50nm，和/或，所述折射率小于1.8的空穴传输材料的折射率为n3，所述第一低折射层的厚度为H3，6nm＜n3×H3＜54nm。
  8. 根据权利要求6所述的有机电致发光器件，其中，还包括第一电极，其中，
    所述第一电极为阳极；
    和/或，最靠近所述第一电极的所述空穴传输区包括所述空穴注入层，该空穴注入层为所述第一低折射层；
    和/或，最靠近所述第一电极的所述空穴传输区包括空穴传输层，该空穴传输层为所述第一低折射层；
    和/或，最靠近所述第一电极的所述空穴传输区包括电子阻挡层，该电子阻挡层为所述第一低折射层。
  9. 根据权利要求8所述的有机电致发光器件，其中，
    每一所述发光单元的所述空穴传输区均分别包括所述空穴传输层，每一所述发光单元的所述空穴传输区的所述空穴传输层均分别为所述第一低折射层；
    和/或，每一所述发光单元的所述空穴传输区均分别包括所述电子阻挡层，每一所述发光单元的所述空穴传输区的所述电子阻挡层均分别为所述第一低折射层。
  10. 根据权利要求6所述的有机电致发光器件，其中，至少两个所述发光单元的所述空穴传输区包括所述空穴传输层；
    和/或，至少两个所述发光单元的所述空穴传输区包括所述电子阻挡层。
  11. 根据权利要求10所述的有机电致发光器件，其中，
    每一所述发光单元的所述空穴传输区均分别包括所述空穴传输层；
    和/或，每一所述发光单元的所述空穴传输区均分别包括所述电子阻挡层。
  12. 根据权利要求10所述的有机电致发光器件，其中，
    所述有机电致发光器件还包括与所述发光单元层叠设置的第一电极，其中，
    所述第一电极为阳极；
    和/或，越靠近所述第一电极的所述空穴传输层的空穴迁移率越小；
    和/或，相邻两个所述空穴传输层的空穴迁移率的比值为1.1～2；
    和/或，越靠近所述第一电极的所述电子阻挡层的空穴迁移率越小；
    和/或，相邻两个所述电子阻挡层的空穴迁移率的比值为1.1～2。
  13. 根据权利要求6所述的有机电致发光器件，其中，还包括与所述第一低折射层相邻的第一相邻层，其中，
    所述第一低折射层的折射率大于或小于所述第一相邻层的折射率；
    和/或，所述第一低折射层的折射率与所述第一相邻层的折射率的差值小于或等于0.5；
    和/或，当所述第一低折射层为空穴注入层时，所述第一相邻层为空穴传输层；当所述第一低折射层为空穴传输层时，所述第一相邻层包括与所述第一低折射层的一侧相邻的空穴注入层、以及与所述第一低折射层的另一侧相邻的电子阻挡层或所述发光层，或者，所述第一相邻层包括与所述第一低折射层的一侧相邻的p型电荷生成层、以及与所述第一低折射层的另一侧相邻的电子阻挡层；当所述第一低折射层为电子阻挡层时，所述第一相邻层包括与所述第一低折射层的一侧相邻的空穴传输层、以及与所述第一低折射层的另一侧相邻的所述发光层。
  14. 根据权利要求1-13任一项所述的有机电致发光器件，其中，还包括位于每两个相邻的所述发光单元之间的电荷生成层，所述电荷生成层包括n型电荷生成层和p型电荷生成层；其中，至少一所述p型电荷生成层为第二低折射层，所述第二低折射层包括折射率小于1.8的第二主体材料；
    和/或，至少一所述电荷生成层还包括位于所述n型电荷生成层与所述p型电荷生成层之间的金属层。
  15. 根据权利要求14所述的有机电致发光器件，其中，
    对于包括所述金属层的所述电荷生成层，其p型电荷生成层邻接的所述空穴传输区包括所述第一低折射层；和/或，所述折射率小于1.8的第二主体材料的折射率大于1.2；
    和/或，所述折射率小于1.8的第二主体材料的折射率为n4，所述第二低折射层的厚度为H4，6nm＜n4×H4＜36nm；
    和/或，所述第二低折射层的厚度H2为5nm～20nm。
  16. 根据权利要求14所述的有机电致发光器件，其中，所述金属层包括元素周期表第IIIA族金属和/或过渡金属。
  17. 根据权利要求16所述的有机电致发光器件，其中，所述金属层包括铝、银、金、钼、钛中的一种或多种。
  18. 根据权利要求14所述的有机电致发光器件，其中，所述有机电致发光器件包括与所述第二低折射层相邻的第二相邻层，其中，
    所述第二低折射层的折射率大于或小于所述第二相邻层的折射率；
    或，所述第二低折射层的折射率与所述第二相邻层的折射率的差值小于或等于0.5；
    和/或，所述第二相邻层包括位于所述第二低折射层的一侧的空穴传输层，和/或，所述第二相邻层包括位于所述第二低折射层的另一侧的n型电荷生成层。
  19. 根据权利要求14所述的有机电致发光器件，其中，
    所述p型电荷生成层包括第二p型掺杂材料，所述p型电荷生成层中，所述第二p型掺杂材料的质量百分含量为3％～10％。
  20. 一种显示装置，其中，包括权利要求1-19任一项所述的有机电致发光器件。
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CN116981281A (zh) * 2023-06-28 2023-10-31 云谷（固安）科技有限公司 有机电致发光器件及显示装置

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