Light emitting device, display substrate and display apparatus

Abstract

The present disclosure provides a light-emitting device, a display substrate and a display apparatus, which belong to the field of display technology. The light-emitting device of the present disclosure includes a first electrode and a second electrode arranged opposite to each other, and at least two layers of light-emitting units arranged between the first electrode and the second electrode and stacked; wherein the light-emitting device also includes: a charge generating unit arranged between the adjacent light-emitting units; the charge generating unit includes a first charge generating unit and a second charge generating unit arranged in sequence along the direction from the second electrode to the first electrode; the material of the first charge generating unit includes a first host material and a first guest material doped in the first host material, and the first charge generating unit is configured to generate a first charge, and the first guest material is configured to absorb the light emitted by the light-emitting unit so that the first charge generating unit generates the first charge.

Description

Technical Field

[0001] The present disclosure belongs to the field of display technology, and particularly relates to a light-emitting device, a display substrate and a display apparatus. Background Art

[0002] With the development of display technology, people have higher and higher requirements for display devices. Compared with the mature liquid crystal display (LCD), organic electroluminescence display (OLED) has the advantages of high color saturation, low driving voltage, wide viewing angle display, flexibility, fast response speed, simple manufacturing process, etc. Therefore, it has gradually replaced the mainstream position of LCD display in the field of small-size display (such as mobile phones, watches and other electronic products).

[0003] A stacked OLED light-emitting device is an OLED in which multiple layers of light-emitting units in the light-emitting device are connected in series through a charge generation layer and is controlled by only one external power source. At the same voltage, compared with a single-layer OLED light-emitting device, a stacked OLED light-emitting device has higher luminous brightness and current efficiency. The luminous brightness and current efficiency increase exponentially with the increase in the number of series-connected light-emitting units, and at the same current density, the stacked OLED has a longer life than a single-layer OLED. However, due to the presence of multiple layers of light-emitting units in a stacked OLED, the operating voltage used is higher than that of a single-layer OLED, and there is a problem of lower power efficiency. The higher operating voltage and lower power efficiency will affect the power consumption of the stacked OLED light-emitting device and reduce the performance of the stacked OLED light-emitting device. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art and provides a light emitting device and a display device.

[0005] In a first aspect, the technical solution adopted to solve the technical problem of the present disclosure is a light-emitting device, which includes a first electrode and a second electrode arranged opposite to each other, and at least two layers of light-emitting units arranged between the first electrode and the second electrode and stacked; the light-emitting device also includes: a charge generating unit arranged between the adjacent light-emitting units;

[0006] The charge generating unit comprises a second charge generating unit and a first charge generating unit which are sequentially arranged along a direction from the first electrode to the second electrode;

[0007] The material of the second charge generating unit includes a first host material and a first guest material doped in the first host material, and the second charge generating unit is configured to generate a second charge; the first charge generating unit includes a second host material and a second guest material doped in the second host material, and the first charge generating unit is configured to generate a first charge;

[0008] The first guest material is configured to absorb light emitted by the light-emitting unit to generate the second charge; and the second guest material is configured to absorb light emitted by the light-emitting unit to generate the first charge.

[0009] Among them, the charge generating unit satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 60%; the charge generating unit satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 75%; the charge generating unit satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 82%.

[0010] Among them, the first charge generating unit satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 80%; the first charge generating unit satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 85%; the first charge generating unit satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 85%.

[0011] Wherein, the thickness of the first charge generating unit is 4nm-10nm.

[0012] Wherein, the first main material includes any one of pyridine, imidazole and triazine ring substances.

[0013] Wherein, the first guest material includes an organic electronic material.

[0014] Wherein, the first guest material includes any one of fullerene derivatives and phthalocyanine compounds.

[0015] Wherein, the doping concentration of the first guest material in the first host material is between 0.5% and 1.5%.

[0016] The second charge generating unit includes a second host material and a second guest material doped in the second host material.

[0017] Among them, the second charge generating unit satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 80%; the second charge generating unit satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 85%; the second charge generating unit satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 85%.

[0018] Wherein, the thickness of the second charge generating unit is 5nm-15nm.

[0019] Wherein, the second main material includes any one of triphenylamine, fluorene, aromatic amine, or carbazole materials.

[0020] The second guest material includes a metal or a metal salt having a work function in the range of 2 electron volts (1.8 eV) to 3.0 eV.

[0021] The second guest material is at least one of ytterbium, lithium, cesium, lithium carbonate or cesium carbonate.

[0022] Wherein, the doping concentration of the second guest material in the second host material is between 0.4% and 2.0%.

[0023] Wherein, the thickness of the second charge generating unit is greater than the thickness of the first charge generating unit.

[0024] Wherein, the light-emitting unit includes a light-emitting layer and a sub-functional layer; the sub-functional layer includes at least one of a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, a hole blocking layer, and an electron blocking layer.

[0025] In a second aspect, the embodiments of the present disclosure further provide a display substrate, which includes the light-emitting device described in any one of the above embodiments.

[0026] Wherein, the display substrate comprises a plurality of pixel units, each pixel unit comprises a plurality of light-emitting devices, and the light-emitting colors of the plurality of light-emitting devices are different;

[0027] The charge generating units of the light emitting devices of different colors are arranged at intervals.

[0028] Wherein, at least some of the charge generating units of the light-emitting devices are made of different materials.

[0029] Among them, the charge generating unit satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 80%; the charge generating unit satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 90%; the charge generating unit satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 92%.

[0030] Wherein, the display substrate includes a plurality of pixel units, each pixel unit includes a plurality of light-emitting devices, and the light-emitting colors of the plurality of light-emitting devices are different;

[0031] The charge generating units of the light emitting devices of different colors are connected as one.

[0032] In a third aspect, an embodiment of the present disclosure further provides a display device, which includes the display substrate described in any one of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the structure of a light-emitting device provided in an embodiment of the present disclosure.

[0034] Figure 2 A schematic diagram of the principle of charge generation by the charge generating unit provided in an embodiment of the present disclosure.

[0035] Figure 3 A schematic diagram of the structure of a light-emitting device provided in an embodiment of the present disclosure.

[0036] Figure 4 A schematic diagram of the structure of another light-emitting device provided in an embodiment of the present disclosure.

[0037] Figure 5 A schematic cross-sectional view of a display substrate provided in an embodiment of the present disclosure.

[0038] Figure 6 A cross-sectional schematic diagram of another display substrate provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0040] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, similar words such as "one", "one" or "the" do not indicate quantity restrictions, but indicate that there is at least one. Similar words such as "include" or "comprise" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Similar words such as "connect" or "connected" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0041] Traditional OLED light-emitting devices are composed of a hole transport layer, a light-emitting layer and an electron transport layer, which are sandwiched between an anode electrode and a cathode electrode. In order to improve the performance of OLED light-emitting devices, multi-layer light-emitting units were designed one after another. For example, organic functional layers such as a hole injection layer, an electron injection layer, an electron blocking layer and a hole blocking layer were continuously added. Later, the concept of a light-emitting unit doped OLED was also proposed. Through the optimization of the thickness of the organic functional layer, the improvement of the preparation process and the use of each organic functional layer, the light-emitting performance of OLED light-emitting devices has been steadily improved.

[0042] In order to further improve the performance of OLED light-emitting devices, the concept of stacked OLED came into being. Stacked OLED is an OLED in which multiple layers of light-emitting units in the light-emitting device 100 are connected in series through a charge generation layer and controlled by only one external power source. At the same voltage, compared with a single-layer OLED light-emitting device, the stacked OLED light-emitting device has higher luminous brightness and current efficiency. The luminous brightness and current efficiency increase exponentially with the increase in the number of series-connected light-emitting units, and at the same current density, the stacked OLED has a longer life than the single-layer OLED. However, due to the presence of multiple layers of light-emitting units in the stacked OLED, the operating voltage used is higher than that of the single-layer OLED, and there is a problem of lower power efficiency. The higher operating voltage and lower power efficiency will affect the power consumption of the stacked OLED light-emitting device and reduce the performance of the stacked OLED light-emitting device.

[0043] In addition, in the related art, in the structure of the stacked OLED light-emitting device, a charge generation layer between the first light-emitting layer and the second light-emitting layer is generally used to generate electrons and holes. After the electrons and holes are separated, the electrons are transferred to and injected into the first light-emitting layer, and the holes are transferred to and injected into the second light-emitting layer; then, they are recombined with the holes generated by the anode at the first light-emitting layer to emit light. At the second light-emitting layer, they are recombined with the electrons generated by the cathode to emit light. Therefore, the charge generation layer has a crucial impact on the performance of the stacked device.

[0044] Along with the technical development of OLED devices, organic solar cells (OSC) also came into being; the principle of OSC is two opposite processes to that of OLED, that is, OLED absorbs charges to generate light, while OSC absorbs light to generate charges. Its principle coincides with the principle of the charge generation layer in the stacked OLED light-emitting device, but the charge generation layer currently used generally does not have the properties of OSC. Therefore, the present invention will focus on the structural optimization of the charge generation unit used in the stacked device, and dope the material used for OSC in the material of the charge generation layer CGL, so that the charge generation layer can absorb the light of the first and second light-emitting layers and generate charges. This solution can improve the performance of the stacked device and improve the problems of high operating voltage and low power efficiency of the stacked device.

[0045] In view of this, the embodiments of the present disclosure provide a light-emitting device, which optimizes the structure of a charge generating unit, is beneficial to the generation of charges in the charge generating unit, and can utilize the photoelectric effect to increase the amount of charge generated, so as to improve the performance of the stacked light-emitting device, such as reducing the operating voltage of the stacked light-emitting device, improving power efficiency, etc.; at the same time, the parameters of the charge generating unit are restricted so that when it converts light energy into electrical energy and releases charges through the photoelectric effect, it will not affect the luminous brightness of the stacked OLED light-emitting device.

[0046] The light emitting device 100 according to the embodiment of the present disclosure is described below in conjunction with the accompanying drawings and specific embodiments.

[0047] In a first aspect, an embodiment of the present disclosure provides a light emitting device 100 . Figure 1 A schematic diagram of a light emitting device provided in an embodiment of the present disclosure is shown in FIG. Figure 1 As shown, the light-emitting device 100 provided in the embodiment of the present disclosure includes a first electrode 1, a second electrode 2, and at least two layers of light-emitting units 3 disposed between the first electrode 1 and the second electrode 2 and stacked, and a charge generating unit 4 is disposed between adjacent light-emitting units 3. The charge generating unit 4 includes a first charge generating unit 41 and a second charge generating unit 42 disposed in sequence along the direction from the second electrode 2 to the first electrode 1.

[0048] It should be noted that the charge generating unit 4 includes an N-type doped charge generating layer and a P-type doped charge generating layer, that is, an N-type organic semiconductor and a P-type organic semiconductor. In the embodiment of the present disclosure, the first charge generating unit 41 includes a P-type doped charge generating layer, and the second charge generating unit 42 includes an N-type doped charge generating layer. The P-type doped charge generating layer and the N-type doped charge generating layer can form a P / N junction structure, and the first charge and the second charge can be generated under the driving of the voltage loaded by the first electrode 1 and the second electrode 2 to excite the first light-emitting layer and the second light-emitting layer to emit light.

[0049] Further, the first charge generating unit 41 is configured to mainly generate first charges for the first light-emitting layer of the light-emitting device 100 to emit light, and the second charge generating unit 42 is configured to mainly generate second charges for the second light-emitting layer of the light-emitting device 100 to emit light. The first charge generating unit 41 includes a first host material and a first guest material doped in the first host material. The first guest material is configured to absorb light emitted by the light-emitting unit 3 so that the first charge generating unit 41 generates first charges. In the embodiment of the present disclosure, the first charges are holes, the second charges are electrons, the first electrode 1 is an anode, and the second electrode 2 is a cathode.

[0050] It should be noted that, in the embodiment of the present disclosure, the light-emitting device 100 is described as including two light-emitting units 3. In the actual design and use of the light-emitting device 100, more than two light-emitting units 3 may be stacked in the light-emitting device 100, and correspondingly, a charge generating unit 4 is provided in each of the two adjacent light-emitting units 3.

[0051] In some examples, the stacked first charge generating unit 41 and the second charge generating unit 42 serve as a charge generating unit 4, and the charge generating unit 4 satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 60%; the charge generating unit 4 satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 75%; the charge generating unit 4 satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 82%.

[0052] It should be noted that the transmittance of the charge generation unit 4 is negatively correlated with the photoelectric conversion efficiency, that is, the greater the transmittance of the charge generation unit 4, the lower the photoelectric conversion efficiency. In order to ensure that the charge generation unit 4 can generate enough first charges and second charges to excite the first light-emitting layer and the second light-emitting layer to maintain the original brightness after reducing the voltage applied by the first electrode 1 and the second electrode 2, it is necessary to ensure that the photoelectric conversion efficiency of the charge generation unit 4 reaches 35% or more. Therefore, it is necessary to reduce the transmittance of the charge generation unit 4 to light by a certain amount to ensure that the photoelectric conversion efficiency reaches 35% or more. However, since the charge generation unit 4 is arranged between the two light-emitting units 3, in order to ensure the light output rate of the two light-emitting units 3, especially the light-emitting unit 3 close to the first electrode 1, its light output needs to pass through the charge generation unit 4. Therefore, while ensuring that the photoelectric conversion efficiency reaches 35%, it is also necessary to ensure that the charge generation unit 4 has a high transmittance.

[0053] In some examples, the first charge generating unit 41 satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 80%; the first charge generating unit 41 satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 85%; the first charge generating unit 41 satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 85%. In order to ensure that the charge generating unit 4 formed by stacking the first charge generating unit 41 and the second charge generating unit 42 has good transmittance of visible light in different wavelength bands, the transmittance of visible light in different wavelength bands of the first charge generating unit 41 needs to be greater than the light transmittance of the charge generating unit 4.

[0054] In some examples, the second charge generating unit 42 satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 80%; the second charge generating unit 42 satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 85%; the second charge generating unit 42 satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 85%. In order to ensure that the charge generating unit 4 formed by stacking the first charge generating unit 41 and the second charge generating unit 42 has good transmittance of visible light in different wavelength bands, the transmittance of visible light in different wavelength bands of the second charge generating unit 42 needs to be greater than the light transmittance of the charge generating unit 4.

[0055] In some examples, the doping concentration of the first guest material in the first host material is between 0.5% and 1.5%. The host material, the guest material, and the doping concentration of the guest material in the host material are all factors that affect the transmittance of the first charge generating unit 41. Therefore, the first charge generating unit 41 in the above example can further change the transmittance by adjusting the first host material, the first guest material, and the doping concentration of the first guest material in the first host material. The first guest material and the doping concentration of the first guest material in the first host material are also factors that affect the light absorption capacity of the first charge generating unit 41. Therefore, the first charge generating unit 41 in the above example can further change the light absorption capacity by adjusting the second guest material or the doping concentration of the second guest material.

[0056] In some examples, the first main material includes any one of pyridine, pyrimidine, and triazine ring substances. For example, the material selected from the following general formula as the basic structure (from left to right: pyridine substance, pyrimidine substance, triazine ring substance):

[0057]

[0058] Wherein, R can be selected from any one of H, F, Cl, Br, alkyl, aryl, heteroalkyl and heteroaryl.

[0059] In some examples, the second main material includes any one of triphenylamine, fluorene, aromatic amine, or carbazole materials, for example, a material selected from the following general formula as a basic structure (from left to right: triphenylamine, carbazole, fluorene, and aromatic amine):

[0060]

[0061] The embodiment of the present disclosure optimizes the structure and restricts the parameters of the first charge generating unit 41 and the second charge generating unit 42, such as the selection of the main material and the guest material, the restriction of the doping concentration of the guest material, etc., so that the first charge generating unit 41 and the second charge generating unit 42 can respectively meet the preset transmittance conditions corresponding to each visible light wavelength range (the "preset transmittance conditions" here can be understood as, for example, for the first charge generating unit 41, the transmittance is greater than 80% in the range of wavelength 380nm to 480nm; the transmittance is greater than 80% in the range of wavelength 480nm to 580nm; the transmittance is greater than 80% in the range of wavelength 480nm to 580nm). 0nm range, the transmittance is greater than 85%; and the transmittance is greater than 85% in the wavelength range of 580nm to 680nm of visible light. ), it is experimentally verified that when the first charge generating unit 41 and the second charge generating unit 42 respectively meet the preset transmittance conditions corresponding to each visible light wavelength range, it is possible to improve the photoelectric conversion efficiency of the first charge generating unit 41 and the second charge generating unit 42 while ensuring that the light extraction rate of the light emitting device 100 is not affected, and improve the performance of the light emitting device 100, reduce the operating voltage, and improve the current efficiency and power efficiency.

[0062] In some examples, the first guest material includes an organic electronic material; the organic electronic material includes any one of fullerene derivatives and phthalocyanine compounds. The first guest material uses an OSC-related material, which can convert light energy into electrical energy through the photoelectric effect. This material is doped into the first host material as the first guest material, and its doping concentration is between 0.5% and 1.5%. Through doping, the first charge generation unit 41 can absorb the light emitted by the light-emitting layers of the two light-emitting units 3 of the light-emitting device 100, and the first charge generation unit 41 can generate and release charges.

[0063] It should be noted that fullerenes include various structures, such as C60 and C70; fullerene derivatives also include various structures, such as C78H16, C60H18 and C60(OH)15, etc. Phthalocyanine compounds include copper phthalocyanine, nickel phthalocyanine, zinc phthalocyanine, cobalt phthalocyanine and iron phthalocyanine, etc. Taking phthalocyanine compounds as an example, for example, the following general formula is selected as the basic structure of the material:

[0064]

[0065] Among them, M can be selected from any one of metal elements such as copper, nickel, zinc, cobalt, iron, etc. The metal element located at the M position chelates with phthalocyanine through two covalent bonds and two coordination bonds to form a highly stable metal phthalocyanine.

[0066] In the disclosed embodiment, Figure 2 A schematic diagram of a charge generating unit generating charges, such as Figure 2As shown, the first charge is a hole, and the second charge is an electron; organic electronic materials, such as fullerene derivatives and phthalocyanine compounds, are usually used as electron acceptor materials, which can absorb a large number of electrons through light irradiation. The first host material is usually used as an electron donor material, and the second host material and the second guest material have the same properties as the first guest material, and are both electron acceptor materials; the first charge generating unit 41 absorbs light energy through light irradiation, so that the doped first guest material absorbs a large number of electrons, and the holes in the first host material are released, so that the first charge generating unit 41 generates holes for stimulating the first light-emitting layer to emit light; while the holes are released, some electrons will move toward the second charge generating unit 42, and under voltage drive, the second charge generating unit 42 and the electrons migrated from the first charge generating unit 41 to the second charge generating unit 42 are used to stimulate the second light-emitting layer to emit light. By doping the first guest material that can perform photoelectric effect into the first charge generating unit 41, the single-electrically driven light-emitting device 100 is changed into a single-drive plus light-driven mode. Compared with the single-electrically driven mode, this mode can reduce the operating voltage of the stacked device, thereby improving the power efficiency of the stacked device. The power efficiency is improved by about 5%.

[0067] In some examples, by doping the second main material with a low work function metal or metal salt so that the doping concentration is between 0.4% and 2.0% and the work function orientation is between 2 electron volts 1.8eV and 3.0eV, the second charge generating unit 42 can satisfy that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 80%; the second charge generating unit 42 satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 85%; the second charge generating unit 42 satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 85%, thereby increasing the speed at which the second charge generating unit 42 generates charges, increasing the speed at which the second charge generating unit 42 separates charges and injects them into other film layers, etc., thereby improving the performance of the light-emitting device 100, reducing the operating voltage of the light-emitting device 100, and improving the current efficiency and power efficiency.

[0068] Furthermore, the second guest material is at least one of ytterbium Yb, lithium Li, cesium Cs, lithium carbonate or cesium carbonate.

[0069] In some examples, the thickness of the first charge generating unit 41 is 4nm-10nm. The thickness of the second charge generating unit 42 is 5nm-15nm. It should be noted that the thickness of the first charge generating unit 41 and the second charge generating unit 42 included in the charge generating unit 4 also affects the photoelectric conversion efficiency and the light extraction rate, so the thickness of the first charge generating unit 41 and the second charge generating unit 42 needs to be designed.

[0070] In some examples, the thickness of the second charge generating unit 42 is greater than the thickness of the first charge generating unit 41. In the disclosed embodiment, the second charge generating unit 42 includes an N-type doped charge generating layer, and the first charge generating unit 41 includes a P-type doped charge generating layer. The N-type doped charge generating layer and the P-type doped charge generating layer can form a P / N junction structure, and can generate second charges and first charges under the drive of the voltage loaded by the first electrode 1 and the second electrode 2 to excite the first light-emitting layer and the second light-emitting layer to emit light. The thickness of the N-type doped charge generating layer and the P-type doped charge generating layer needs to be greater than the thickness of the space charge depletion region after the N-type doped charge generating layer and the P-type doped charge generating layer form a P / N junction, and the thickness of the N-type doped charge generating layer is greater than the thickness of the P-type doped charge generating layer. The width of the P / N junction space charge depletion region will change with the adjustment of the N-type doping concentration and the P-type doping concentration. The fill factor is an important parameter for evaluating the output characteristics of the charge generating unit 4. The higher its value, the higher the photoelectric conversion efficiency. By making the thickness of the N-type doped charge generation layer greater than the thickness of the P-type doped charge generation layer, the filling factor of the second guest material and the first guest material in the charge generation unit 4 can reach 70%-90%.

[0071] In some examples, the light-emitting unit 3 includes a light-emitting layer and a sub-functional layer; the sub-functional layer includes at least one of a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, a hole blocking layer, and an electron blocking layer. In order to ensure the light-emitting effect of the light-emitting unit 3, the light-emitting unit 3 can be arranged in the direction from the first electrode 1 to the second electrode 2 in sequence: a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer. Figure 3 As shown, when the light-emitting device 100 includes two light-emitting units 3, a hole injection layer HIL, a second hole transport layer HTL2, a second electron blocking layer EBL2, a second light-emitting layer EML2, a second electron transport layer ETL2, a second charge generating unit 42, a first charge generating unit 41, a first hole injection layer HTL1, a first electron blocking layer EBL1, a first light-emitting layer EML1, a hole blocking layer HBL, a first electron transport layer ETL1, and a first electron injection layer EIL are sequentially arranged from the first electrode 1 to the second electrode 2.

[0072] In some examples, such as Figure 4As shown, the light-emitting device 100 includes two light-emitting units 3 arranged in layers, and the light-emitting unit 3 includes at least a light-emitting layer, and the light-emitting layer includes a plurality of sub-light-emitting layers arranged in layers, and the light-emitting colors of each light-emitting layer are different. There may be three sub-light-emitting layers, which are a red light-emitting layer REBL, a green light-emitting layer GEBL, and a blue light-emitting layer BEBL in the direction from the first electrode 1 to the second electrode 2; there may also be two light-emitting layers, which are a yellow light-emitting layer YEBL and a blue light-emitting layer BEBL in the direction from the first electrode 1 to the second electrode 2; they can be mixed to emit white light. This method of stacking the light-emitting layers can be used not only on large-size white light OLED display devices, but also on backlight sources of quantum dot film layers.

[0073] Furthermore, in the case of a light-emitting unit 3 having a stacked light-emitting layer, the charge generating unit 4 between adjacent light-emitting units 3 satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 65%; the charge generating unit 4 satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 75%; the charge generating unit 4 satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 80%.

[0074] In a second aspect, the present disclosure also provides a display substrate. Figure 5 A schematic cross-sectional view of a display substrate provided in an embodiment of the present disclosure; Figure 6 A cross-sectional schematic diagram of another display substrate provided in an embodiment of the present disclosure is shown in FIG. Figure 5 and Figure 6 As shown, the display substrate in the embodiment of the present disclosure includes a plurality of pixel units, each pixel unit includes a plurality of light-emitting devices 100, and the colors of the plurality of light-emitting devices 100 are different. In the embodiment of the present disclosure, taking the light-emitting device 100 including three colors, and the three-color light-emitting devices 100 each including two light-emitting units 3 as an example, the three colors are a red light-emitting device 100, a green light-emitting device 100, and a blue light-emitting device 100, and the light-emitting devices 100 of the three colors can be respectively connected to an anode corresponding to one of them. The light emitted by the light-emitting layer in the red light-emitting device 100 corresponds to visible light with a wavelength of 380nm to 480nm, the light emitted by the light-emitting layer in the green light-emitting device 100 corresponds to visible light with a wavelength of 480nm to 580nm, and the light emitted by the light-emitting layer in the blue light-emitting device 100 corresponds to visible light with a wavelength of 580nm to 680nm.

[0075] In some examples, such as Figure 5As shown, a blue light-emitting device 100, a green light-emitting device 100 and a red light-emitting device 100 are arranged adjacent to each other from left to right. Three adjacent light-emitting devices 100 correspond to three first electrodes 1 respectively. During the manufacturing process, the common functional film layer can be made into an integrated structure to reduce the mask cost generated during the manufacturing process. The hole injection layer HIL, the second hole transport layer HTL2, the second hole blocking layer HBL2, the second electron transport layer ETL2, the first hole transport layer HTL1, the first hole blocking layer HBL1, the first electron transport layer ETL1, the electron injection layer EIL, and the second electrode 2 are made into an integrated structure. The above parts of each light-emitting device 100 are integrated, which can reduce the mask cost.

[0076] Furthermore, different guest materials have different absorption capabilities for visible light in different wavelength ranges, and different materials have different light transmittances. Different guest materials are selected to be doped in the main material of the first charge generating unit 41, so that the first charge generating unit 41 corresponding to the red light-emitting layer BEML, the green light-emitting layer GEML and the blue light-emitting layer BMEL has a stronger ability to absorb light, and at the same time, the charge generating unit 4 has a higher working efficiency and can release more charges. By controlling the transmittance of the charge generating unit 4, the charge generating units 4 corresponding to the three-color light-emitting layers have the same or similar absorption capabilities for light in different wavelength bands, so that the charge generating unit 4 absorbs light more efficiently, ensuring the photoelectric conversion efficiency, and can better control the luminous brightness of the three-color light-emitting layers, ensuring that the final display result of the light-emitting device 100 will not have color deviation, and improving power efficiency.

[0077] In some examples, during the manufacturing process, a mask is added to separate the first charge generating unit 41 and the second charge generating unit 42, so that the charge generating units of light-emitting devices of different colors are arranged at intervals, and the host material and the guest material used in the first charge generating unit 41 and the second charge generating unit 42 of the light-emitting devices 100 of different colors need to be different. This makes the charge generating units 4 corresponding to the light-emitting layers of the three colors have the same or similar absorption capacity for light of different wavelengths, so that the charge generating units 4 absorb light more efficiently, ensure the photoelectric conversion efficiency, and better control the luminous brightness of the three color light-emitting layers, ensure that the final display result of the light-emitting device 100 will not have color deviation, and improve power efficiency.

[0078] In some examples, the materials of the first charge generating unit 41 and the second charge generating unit 42 of each charge generating unit 4 are different; the stacked first charge generating unit 41 and the second charge generating unit 42 are used as a charge generating unit 4, and each charge generating unit 4 satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 80%; the second charge generating unit 42 satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 90%; the second charge generating unit 42 satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 92%.

[0079] It should be noted that the transmittance of the charge generation unit 4 is negatively correlated with the photoelectric conversion efficiency, that is, the greater the transmittance of the charge generation unit 4, the lower the photoelectric conversion efficiency. In order to ensure that the charge generation unit 4 can generate enough first charges and second charges to excite the first light-emitting layer and the second light-emitting layer to maintain the original brightness after reducing the voltage applied by the first electrode 1 and the second electrode 2, it is necessary to ensure that the photoelectric conversion efficiency of the charge generation unit 4 reaches 35% or more. Therefore, it is necessary to reduce the transmittance of the charge generation unit 4 to light by a certain amount to ensure that the photoelectric conversion efficiency reaches 35% or more. However, since the charge generation unit 4 is arranged between the two light-emitting units 3, in order to ensure the light output rate of the two light-emitting units 3, especially the light-emitting unit 3 close to the first electrode 1, its light output needs to pass through the charge generation unit 4. Therefore, while ensuring that the photoelectric conversion efficiency reaches 35%, it is also necessary to ensure that the charge generation unit 4 has a high transmittance.

[0080] In some examples, the first guest materials of the second charge generating units 42 of each light emitting device 100 are different; the first charge generating unit 41 satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 80%; the first charge generating unit 41 satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 90%; the first charge generating unit 41 satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 92%. In order to ensure that the charge generating unit 4 formed by stacking the first charge generating unit 41 and the second charge generating unit 42 has good transmittance of visible light in different wavelength bands, the transmittance of visible light in different wavelength bands of the second charge generating unit 42 can be greater than the light transmittance of the charge generating unit 4.

[0081] In some examples, such as Figure 6As shown, in order to reduce the process flow and save the manufacturing cost, the first charge generating unit 41 and the second charge generating unit 42 are also made into an integrated structure. And it satisfies that the transmittance of the first charge generating unit 41 and the second charge generating unit 42 of each light-emitting device 100 is greater than 80% when the wavelength of visible light is within the range of 380nm to 480nm; the transmittance of the first charge generating unit 41 and the second charge generating unit 42 is greater than 90% when the wavelength of visible light is within the range of 480nm to 580nm; the transmittance of the first charge generating unit 41 and the second charge generating unit 42 is greater than 92% when the wavelength of visible light is within the range of 580nm to 680nm. The thickness of the first charge generating unit 41 is 4nm-10nm, and the thickness of the second charge generating unit 42 is 5nm-15nm.

[0082] In a third aspect, the embodiments of the present disclosure further provide a display device, which includes the light-emitting device 100 of any one of the above embodiments. The display panel provided by the embodiments of the present disclosure has great advantages in being applied to products with small and medium-sized display panels, such as mobile phones, tablet computers, vehicle-mounted devices, wearable devices, etc. Since the stacked light-emitting device 100 in the display panel improves power efficiency and current efficiency and reduces operating voltage compared to the traditional stacked light-emitting device 100, the display effect of the stacked light-emitting device 100 on the display panel can be better optimized, such as light brightness, color and other effects.

[0083] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A light-emitting device, comprising a first electrode and a second electrode arranged opposite to each other, and at least two layers of light-emitting units arranged between the first electrode and the second electrode and stacked; characterized in that: The light emitting device further comprises: a charge generating unit disposed between the adjacent light emitting units; The charge generating unit satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 60%; the charge generating unit satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 75%; the charge generating unit satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 80%; The charge generating unit comprises a first charge generating unit and a second charge generating unit which are sequentially arranged in a direction from the second electrode to the first electrode; The transmittance of the first charge generating unit to visible light of different wavelength bands is greater than the light transmittance of the charge generating unit; the transmittance of the first charge generating unit to visible light within the wavelength range of 380nm to 480nm is greater than 80%; the transmittance of the first charge generating unit to visible light within the wavelength range of 480nm to 580nm is greater than 85%; the transmittance of the first charge generating unit to visible light within the wavelength range of 580nm to 680nm is greater than 85%; the material of the first charge generating unit includes a first host material and a first guest material doped in the first host material, and the first charge generating unit is configured to generate a first charge, and the first guest material is configured to absorb the light emitted by the light-emitting unit so that the first charge generating unit generates the first charge; the doping concentration of the first guest material in the first host material is between 0.5% and 1.5%; The transmittance of the second charge generating unit to visible light of different wavelength bands is greater than the light transmittance of the charge generating unit; the transmittance of the second charge generating unit to visible light in the wavelength range of 380nm to 480nm is greater than 80%; the transmittance of the second charge generating unit to visible light in the wavelength range of 480nm to 580nm is greater than 85%; the transmittance of the second charge generating unit to visible light in the wavelength range of 580nm to 680nm is greater than 85%; the second charge generating unit includes a second main material and a second guest material doped in the second main material; the doping concentration of the second guest material in the second main material is between 0.4% and 2.0%; The thickness of the second charge generating unit is greater than that of the first charge generating unit; the thickness of the first charge generating unit is 4nm-10nm; the thickness of the second charge generating unit is 5nm-15nm.

2. The light emitting device according to claim 1, characterized in that: The first main material includes any one of pyridine, pyrimidine and triazine ring substances.

3. The light emitting device according to claim 1, characterized in that: The first guest material includes an organic electronic type material.

4. The light emitting device according to claim 3, characterized in that: The first guest material includes any one of fullerene derivatives and phthalocyanine compounds.

5. The light emitting device according to claim 1, characterized in that: The second host material includes any one of triphenylamine, fluorene, aromatic amine, or carbazole materials.

6. The light emitting device according to claim 1, characterized in that: The second guest material includes a metal or a metal salt having a work function in the range of 2 electron volts (1.8 eV) to 3.0 eV.

7. The light emitting device according to claim 6, characterized in that: The second guest material is at least one of ytterbium, lithium, cesium, lithium carbonate or cesium carbonate.

8. The light emitting device according to claim 1, characterized in that: The light-emitting unit includes a light-emitting layer and a sub-functional layer; the sub-functional layer includes at least one of a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, a hole blocking layer, and an electron blocking layer.

9. A display substrate, characterized in that: The display substrate comprises the light emitting device according to any one of claims 1-8.

10. The display substrate according to claim 9, characterized in that: The display substrate includes a plurality of pixel units, each of which includes a plurality of light-emitting devices, and the light-emitting colors of the plurality of light-emitting devices are different; The charge generating units of the light emitting devices of different colors are arranged at intervals.

11. The display substrate according to claim 10, characterized in that: The charge generating units of at least some of the light emitting devices are made of different materials.

12. The display substrate according to claim 10, characterized in that: The charge generating unit satisfies that the transmittance of visible light in the wavelength range of 380nm to 480nm is greater than 80%; the charge generating unit satisfies that the transmittance of visible light in the wavelength range of 480nm to 580nm is greater than 90%; the charge generating unit satisfies that the transmittance of visible light in the wavelength range of 580nm to 680nm is greater than 92%.

13. The display substrate according to claim 9, characterized in that: The display substrate includes a plurality of pixel units, each of which includes a plurality of light-emitting devices, and the light-emitting colors of the plurality of light-emitting devices are different; The charge generating units of the light emitting devices of different colors are connected as one.

14. A display device, characterized in that: The display device comprises the display substrate according to any one of claims 9 to 13.

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