Laminated light-emitting device, display panel and display device

Abstract

The invention discloses a laminated light-emitting device, which comprises a first light-emitting function part and a second light-emitting function part, and is characterized in that the thickness of the second light-emitting function part is smaller than or equal to that of the first light-emitting function part; the reduction effect of the first light-emitting function part on the surface plasmon effect is better than the reduction effect of the second light-emitting function part on the surface plasmon effect, so that the improvement of the light extraction efficiency of the light-emitting material layer close to the first electrode is better than the improvement of the light extraction efficiency of the light-emitting material layer far away from the first electrode. Therefore, the light extraction efficiency of the two light-emitting material layers can be well balanced, the light extraction efficiency of different light-emitting material layers tends to be consistent, the light extraction efficiency of the whole laminated light-emitting device is improved, and the power efficiency of the laminated light-emitting device is further improved. The invention further provides a display panel comprising the laminated light-emitting device and a display device comprising the display panel.

Description

Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular to a stacked light-emitting device, a display panel and a display apparatus. Background Art

[0002] A stacked light-emitting device is a device that connects multiple light-emitting units in series through a charge generation layer. Compared with a single-layer light-emitting device, a stacked light-emitting device has higher luminous brightness, current efficiency and service life.

[0003] However, in practical applications, stacked light-emitting devices generally have the problem of low power efficiency compared to single-layer light-emitting devices.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] The purpose of the present disclosure is to overcome the common problems of high operating voltage and low power efficiency of stacked light-emitting devices compared to single-layer light-emitting devices, and to provide a stacked light-emitting device, a display panel and a display device.

[0006] According to one aspect of the present disclosure, there is provided a stacked light-emitting device, comprising a first electrode, a second electrode, a first light-emitting material layer, a second light-emitting material layer, a first light-emitting functional layer and a second light-emitting functional layer, wherein the second electrode is arranged opposite to the first electrode; the first light-emitting material layer is arranged between the first electrode and the second electrode, and the first light-emitting material layer comprises a first blue light-emitting unit; the second light-emitting material layer is arranged between the first light-emitting material layer and the second electrode, and the second light-emitting material layer comprises a second blue light-emitting unit; the first light-emitting functional layer comprises a first light-emitting functional portion, and the first light-emitting functional portion is arranged between the first blue light-emitting unit and the first electrode; the second light-emitting functional layer comprises a second light-emitting functional portion, and the second light-emitting functional portion is arranged between the first blue light-emitting unit and the second blue light-emitting unit, and the thickness of the second light-emitting functional portion is less than or equal to the thickness of the first light-emitting functional portion.

[0007] In one embodiment of the present disclosure, the thickness of the first blue light-emitting unit is greater than or equal to the thickness of the second blue light-emitting unit.

[0008] In one embodiment of the present disclosure, the first light-emitting material layer also includes a first red light-emitting unit, the second light-emitting material layer includes a second red light-emitting unit, the first light-emitting functional layer also includes a third light-emitting functional portion, the third light-emitting functional portion is arranged between the first red light-emitting unit and the first electrode, the second light-emitting functional layer also includes a fourth light-emitting functional portion, the fourth light-emitting functional portion is arranged between the first red light-emitting unit and the second red light-emitting unit, and the thickness of the fourth light-emitting functional portion is greater than or equal to the thickness of the third light-emitting functional portion.

[0009] In one embodiment of the present disclosure, the first light-emitting material layer also includes a first green light-emitting unit, the second light-emitting material layer also includes a second green light-emitting unit, the first light-emitting functional layer also includes a fifth light-emitting functional portion, the fifth light-emitting functional portion is arranged between the first green light-emitting unit and the first electrode, the second light-emitting functional layer also includes a sixth light-emitting functional portion, the fourth light-emitting functional portion is arranged between the first green light-emitting unit and the second green light-emitting unit, and the thickness of the sixth light-emitting functional portion is greater than or equal to the thickness of the fifth light-emitting functional portion.

[0010] In one embodiment of the present disclosure, a first hole transport layer is provided on a side of the first light-emitting functional unit, the third light-emitting functional unit and the fifth light-emitting functional unit close to the first electrode, and a second hole transport layer is provided on a side of the second light-emitting functional unit, the fourth light-emitting functional unit and the sixth light-emitting functional unit close to the first electrode, and the thickness of the first hole transport layer is greater than or equal to the thickness of the second hole transport layer.

[0011] In one embodiment of the present disclosure, the refractive index of the first hole transport layer is less than the refractive index of the second hole transport layer.

[0012] In one embodiment of the present disclosure, when the wavelength of the output light of the stacked light emitting device is 455-462 nm, the difference between the refractive index of the first hole transport layer and the refractive index of the second hole transport layer is greater than or equal to 0.2.

[0013] In one embodiment of the present disclosure, the first light-emitting functional portion includes a first electron blocking unit, and the second light-emitting functional portion includes a second electron blocking unit. The first electron blocking unit is arranged between the first hole transport layer and the first blue light-emitting unit, and the second electron blocking unit is arranged between the second hole transport layer and the second blue light-emitting unit. The thickness of the first electron blocking unit is greater than or equal to the thickness of the second electron blocking unit.

[0014] In one embodiment of the present disclosure, the third light-emitting functional portion includes a third electron blocking element, and the fourth light-emitting functional portion includes a fourth electron blocking unit. The third electron blocking unit is arranged between the first hole transport layer and the first red light-emitting unit, and the fourth electron blocking unit is arranged between the second hole transport layer and the second red light-emitting unit. The thickness of the third electron blocking unit is less than or equal to the thickness of the fourth electron blocking unit.

[0015] In one embodiment of the present disclosure, the fifth light-emitting functional portion includes a fifth electron blocking unit, the sixth light-emitting functional portion includes a sixth electron blocking unit, the fifth electron blocking unit is arranged between the first hole transport layer and the first green light-emitting unit, the sixth electron blocking unit is arranged between the second hole transport layer and the second green light-emitting unit, and the thickness of the fifth electron blocking unit is less than or equal to the thickness of the sixth electron blocking unit.

[0016] In one embodiment of the present disclosure, when the wavelength of the output light of the stacked light emitting device is 455-462 nm, the refractive index of the first electron blocking unit is less than or equal to the refractive index of the second electron blocking unit.

[0017] In one embodiment of the present disclosure, the second light-emitting functional layer includes a first hole blocking layer, a first electron transport layer and a charge generating layer, the charge generating layer is arranged between the first light-emitting material layer and the second hole transport layer, the charge generating layer includes an N-type doped layer and a P-type doped layer, the P-type doped layer is arranged on the side of the N-type doped layer away from the first light-emitting material layer, the first electron transport layer is arranged on the side of the N-type doped layer close to the first light-emitting material layer, the first hole blocking layer is arranged on the side of the first electron transport layer close to the first light-emitting material layer, the stacked light-emitting device also includes a third light-emitting functional layer, the third light-emitting functional layer includes a second hole blocking layer, the second hole blocking layer is arranged on the side of the second light-emitting material layer away from the first electrode, and the electron mobility of the first hole blocking layer is equal to the electron mobility of the second hole blocking layer.

[0018] In one embodiment of the present disclosure, the second light-emitting functional layer includes a first hole blocking layer and a charge generating layer, the charge generating layer is arranged between the first light-emitting material layer and the second hole transport layer, the charge generating layer includes an N-type doped layer and a P-type doped layer, the P-type doped layer is arranged on the side of the N-type doped layer away from the first light-emitting material layer, the first hole blocking layer is arranged on the side of the N-type doped layer close to the first light-emitting material layer, the third light-emitting functional layer includes a second hole blocking layer, the second hole blocking layer is arranged on the side of the second light-emitting material layer away from the first electrode, the stacked light-emitting device also includes a third light-emitting functional layer, the third light-emitting functional layer includes a second hole blocking layer, the second hole blocking layer is arranged on the side of the second light-emitting material layer away from the first electrode, and the electron mobility of the first hole blocking layer is greater than the electron mobility of the second hole blocking layer.

[0019] In one embodiment of the present disclosure, the first light-emitting material layer also includes a first red light-emitting unit and a first green light-emitting unit, the second light-emitting material layer includes a second red light-emitting unit and a second green light-emitting unit, the sum of the thicknesses of the first red light-emitting unit and the second red light-emitting unit is greater than or equal to the sum of the thicknesses of the first green light-emitting unit and the second green light-emitting unit, and the sum of the thicknesses of the first green light-emitting unit and the second green light-emitting unit is greater than or equal to the sum of the thicknesses of the first blue light-emitting unit and the second blue light-emitting unit.

[0020] In one embodiment of the present disclosure, the doping material of the N-type doping layer is a low work function metal or a low work function metal salt, and the doping concentration of the N-type doping layer is in the range of 1.2%±0.8%, and the doping material of the P-type doping layer is an organic electronic material or an inorganic metal oxide material, and the doping concentration of the P-type doping layer is in the range of 10%±5%.

[0021] According to another aspect of the present disclosure, a display panel is provided, comprising the stacked light emitting device provided by any one aspect of the present disclosure.

[0022] According to another aspect of the present disclosure, a display device is provided, including the display panel provided by another aspect of the present disclosure.

[0023] The stacked light-emitting device disclosed in the present invention includes a first light-emitting functional part and a second light-emitting functional part. The first light-emitting functional part is arranged between the first light-emitting unit and the first electrode, and the second light-emitting functional part is connected between two adjacent first light-emitting units. The first light-emitting functional part and the second light-emitting functional part can reduce the influence of the surface plasmon effect on the light extraction efficiency. Since the thickness of the second light-emitting functional part is less than or equal to the thickness of the first light-emitting functional part, the first light-emitting functional part has a better effect of reducing the surface plasmon effect than the second light-emitting functional part, so that the improvement of the light extraction efficiency of the light-emitting material layer close to the first electrode is better than the improvement of the light extraction efficiency of the light-emitting material layer far from the first electrode. In this way, the light extraction efficiencies of the two light-emitting material layers can be better balanced, the light extraction efficiencies of different light-emitting material layers can be made consistent, the light extraction efficiency of the entire stacked light-emitting device is improved, and the power efficiency of the stacked light-emitting device is improved.

[0024] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0026] Figure 1 A schematic cross-sectional view of a stacked light-emitting device according to an embodiment of the present disclosure when the second light-emitting functional layer includes a first electron transport layer.

[0027] Figure 2 A schematic diagram of a curve showing the relationship between driving voltage and brightness of two groups of blue stacked sub-light-emitting devices involved in an embodiment of the present disclosure when an optical test is performed on two groups of blue stacked sub-light-emitting devices because the second light-emitting functional layer includes a first electron transport layer.

[0028] Figure 3 The cross-sectional schematic diagram of the stacked light-emitting device involved in the embodiment of the present disclosure is when the second light-emitting functional layer does not include the first electron transport layer.

[0029] Figure 4When the second light-emitting functional layer does not include the first electron transport layer, when two groups of blue stacked sub-light-emitting devices are optically tested, a curve diagram of the relationship between the driving voltage and the brightness of the two groups of blue stacked sub-light-emitting devices involved in an embodiment of the present disclosure is shown.

[0030] In the figure: 1-first electrode, 2-second electrode, 3-first luminescent material layer, 31-first red luminescent unit, 32-first green luminescent unit, 33-first blue luminescent unit, 4-second luminescent material layer, 41-second red luminescent unit, 42-second green luminescent unit, 43-second blue luminescent unit, 5-first luminescent functional layer, 51-hole injection layer, 52-first hole transport layer, 53-first electron blocking layer, 531-first electron blocking unit, 532-third electron blocking unit, 533-fifth electron blocking unit, 501-first luminescent functional unit, 502-third luminescent functional unit, 503-fifth luminescent functional unit, 6-second luminescent functional unit Energy layer, 61-first hole blocking layer, 62-first electron transport layer, 63-charge generation layer, 631-N-type doping layer, 632-P-type doping layer, 64-second hole transport layer, 65-second electron blocking layer, 651-second electron blocking unit, 652-fourth electron blocking unit, 653-sixth electron blocking unit, 601-second light-emitting functional part, 602-fourth light-emitting functional part, 603-sixth light-emitting functional part, 7-third light-emitting functional layer, 71-second hole blocking layer, 72-second electron transport layer, 73 electron injection layer, 100-blue stacked sub-light-emitting device, 200-red stacked sub-light-emitting device, 300-green stacked sub-light-emitting device. DETAILED DESCRIPTION

[0031] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will be comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their detailed description will be omitted. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0032] Although relative terms such as "upper" and "lower" are used in this specification to describe the relative relationship of one component of the illustration to another component, these terms are used in this specification only for convenience, such as according to the orientation of the examples described in the drawings. It is understood that if the device of the illustration is turned upside down, the component described as "upper" will become the component "lower". When a structure is "on" other structures, it may mean that the structure is formed integrally on the other structure, or that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure through another structure.

[0033] The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express an open-ended inclusive meaning and mean that additional elements / components / etc. may exist in addition to the listed elements / components / etc.; the terms "first", "second" and "third" etc. are used merely as labels and are not intended to limit the quantity of their objects.

[0034] Compared with liquid crystal display panels, organic light emitting diode (OLED) display panels have the advantages of high color saturation, low driving voltage, wide viewing angle display, flexibility, fast response speed, simple manufacturing process, etc. Therefore, they have gradually replaced the mainstream position of liquid crystal display panels in the field of small-size displays (for example, mobile phones, watches and other electronic products), and their development trend is rapidly concentrating on the medium and large-size fields. At present, notebooks and car display devices using organic light emitting diode display panels have appeared.

[0035] The organic light emitting diode includes a hole transport layer, a light emitting material layer and an electron transport layer. The hole transport layer and the electron transport layer are arranged between the first electrode 1 (indium tin oxide ITO) and the second electrode 2 (Al), and the light emitting material layer is arranged between the hole transport layer and the electron transport layer. In order to improve the performance of the light emitting device, a light emitting layer doped light emitting device has also been proposed. A light emitting layer doped light emitting device is an organic light emitting device that adjusts its light emitting characteristics by adding specific dopants to the light emitting material layer. These dopants can be fluorescent dyes, phosphorescent dyes or other types of light emitting materials that can absorb energy and emit light of a specific color. By precisely controlling the concentration and type of the dopant, the light emitting color, brightness and efficiency of the device can be optimized.

[0036] In order to further improve the light-emitting performance of the light-emitting device, a stacked light-emitting device came into being. The stacked light-emitting device is a light-emitting device in which multiple light-emitting elements are connected in series through the charge generation layer 63 and is controlled by only one external power source. Compared with a single-layer light-emitting device, the stacked light-emitting device has higher light-emitting brightness and current efficiency. The light-emitting brightness and current efficiency increase exponentially with the increase in the number of light-emitting elements connected in series. Under the same current density, the service life of the stacked light-emitting device is also increased exponentially compared with the single-layer light-emitting device.

[0037] The key reason why the stacked light-emitting device has better performance than the single-layer light-emitting device is that there is a charge generation layer 63 inside it, which is one of the most important factors affecting the performance of the stacked device. At present, the charge generation layer 63 in the stacked light-emitting device is generally between the first light-emitting material layer 3 and the second light-emitting material layer 4. The charge generation layer 63 is used to generate electrons and holes. After separation, the electrons and holes are injected and transmitted to the first light-emitting material layer 3 and the second light-emitting material layer 4 respectively, and recombine with the holes injected by the first electrode 1 and the electrons injected by the second electrode 2.

[0038] At present, in order to obtain a higher aperture ratio, light-emitting devices generally adopt a top emission structure. Top emission has a higher aperture ratio and device efficiency. For total reflection, the first electrode 1 basically adopts a thicker silver electrode. The silver electrode can improve the light emission rate, but it will produce plasma resonance effect and waveguide effect. The light-emitting device will lose a considerable proportion of light efficiency due to the plasma resonance effect and waveguide effect. Among them, surface plasma will cause about 30-35% of light loss, resulting in a light output ratio of only about 20-25%. It can be seen that the current stacked light-emitting devices generally have the problem of low power efficiency compared with single-layer light-emitting devices.

[0039] Therefore, in order to improve the light extraction efficiency of the stacked light-emitting device and reduce the optical loss caused by the two effects, the thickness of the film layer between the first electrode 1 and the light-emitting material layer and between adjacent light-emitting material layers in the stacked light-emitting device is limited to ensure that the light-emitting area of ​​the stacked light-emitting device is as far away from the first electrode 1 as possible.

[0040] Based on this, the present disclosure provides a stacked light emitting device. Figures 1 to 4As shown, the stacked light-emitting device includes a first electrode 1, a second electrode 2, at least two light-emitting material layers, a first light-emitting functional layer 5 and a second light-emitting functional layer 6, wherein the second electrode 2 is arranged opposite to the first electrode 1; at least two light-emitting material layers are arranged between the first electrode 1 and the second electrode 2, and each light-emitting material layer includes a first light-emitting unit; the first light-emitting functional layer 5 includes a first light-emitting functional portion 501, and the first light-emitting functional portion 501 is arranged between the first light-emitting unit and the first electrode 1; the second light-emitting functional layer 6 includes a second light-emitting functional portion 601, and the second light-emitting functional portion 601 is connected between two adjacent first light-emitting units, and the thickness of the second light-emitting functional portion 601 is less than or equal to the thickness of the first light-emitting functional portion 501.

[0041] The stacked light-emitting device includes a first light-emitting functional portion 501 and a second light-emitting functional portion 601. The first light-emitting functional portion 501 is arranged between the first light-emitting unit and the first electrode 1, and the second light-emitting functional portion 601 is connected between two adjacent first light-emitting units. The first light-emitting functional portion 501 and the second light-emitting functional portion 601 can reduce the influence of the surface plasmon effect on the light extraction efficiency. Since the thickness of the second light-emitting functional portion 601 is less than or equal to the thickness of the first light-emitting functional portion 501, the first light-emitting functional portion 501 has a better effect of reducing the surface plasmon effect than the second light-emitting functional portion 601, so that the improvement of the light extraction efficiency of the light-emitting material layer close to the first electrode 1 is better than the improvement of the light extraction efficiency of the light-emitting material layer far from the first electrode 1. In this way, the light extraction efficiencies of the two light-emitting material layers can be better balanced, and the light extraction efficiencies of different light-emitting material layers can be made consistent, thereby improving the light extraction efficiency of the entire stacked light-emitting device, and further improving the power efficiency of the stacked light-emitting device.

[0042] The stacked light emitting device involved in the embodiment of the present disclosure is described in detail below with reference to specific examples.

[0043] like Figure 1 As shown, the stacked light-emitting device includes a first electrode 1, a second electrode 2, a first light-emitting material layer 3, a second light-emitting material layer 4, a first light-emitting functional layer 5, a second light-emitting functional layer 6 and a third light-emitting functional layer 7. The first light-emitting material layer 3 is arranged between the first electrode 1 and the second electrode 2, the second light-emitting material layer 4 is arranged between the first light-emitting material layer 3 and the second electrode 2, the first light-emitting functional layer 5 is arranged between the first electrode 1 and the first light-emitting material layer 3, the second light-emitting functional layer 6 is arranged between the first light-emitting material layer 3 and the second light-emitting material layer 4, and the third light-emitting functional layer 7 is arranged between the second light-emitting material layer 4 and the second electrode 2.

[0044] The first light-emitting functional layer 5 includes a hole injection layer 51, a first hole transport layer 52 and a first electron blocking layer 53. The hole injection layer 51 is arranged between the first electrode 1 and the second electrode 2, the first hole transport layer 52 is arranged on the side of the hole injection layer 51 away from the first electrode 1, and the first electron blocking layer 53 is arranged on the side of the first hole transport layer 52 away from the first electrode 1. The first electron blocking layer 53 includes a first electron blocking unit 531, a third electron blocking unit 532 and a fifth electron blocking unit 533. The thickness of the first electron blocking unit 531 is less than the thickness of the fifth electron blocking unit 533, and the thickness of the fifth electron blocking unit 533 is less than the thickness of the third electron blocking unit 532.

[0045] The first light-emitting material layer 3 includes a first red light-emitting unit 31, a first green light-emitting unit 32 and a first blue light-emitting unit 33. The first blue light-emitting unit 33 is arranged on a side of the first electron blocking unit 531 away from the first electrode 1, the first red light-emitting unit 31 is arranged on a side of the third electron blocking unit 532 away from the first electrode 1, and the first green light-emitting unit 32 is arranged on a side of the fifth electron blocking unit 533 away from the first electrode 1. A side of the first red light-emitting unit 31 away from the first electrode 1 is higher than a side of the first green light-emitting unit 32 away from the first electrode 1, and a side of the first green light-emitting unit 32 away from the first electrode 1 is higher than a side of the first blue light-emitting unit 33 away from the first electrode 1.

[0046] The second light-emitting functional layer 6 includes a first hole blocking layer 61, a first electron transport layer 62, a charge generating layer 63, a second hole transport layer 64 and a second electron blocking layer 65. The first hole blocking layer 61 is arranged on the side of the first electron blocking unit 531 away from the first electrode 1, the first electron transport layer 62 is arranged on the side of the first hole blocking layer 61 away from the first electrode 1, the charge generating layer 63 includes an N-type doping layer 631 and a P-type doping layer 632, the N-type doping layer 631 is arranged on the side of the first electron transport layer 62 away from the first electrode 1, the P-type doping layer 632 is arranged on the side of the N-type doping layer 631 away from the first electrode 1, and the second hole transport layer 64 is arranged on the side of the P-type doping layer 632 away from the first electrode 1.

[0047] The doping material of the N-type doping layer 631 is a low work function metal or a low work function metal salt, and the doping concentration of the N-type doping layer 631 is within the range of 1.2%±0.8%, and the doping material of the P-type doping layer 632 is an organic electronic material or an inorganic metal oxide material, and the doping concentration of the P-type doping layer 632 is within the range of 10%±5%. When the doping material of the N-type doping layer 631 is a low work function metal, the doping material of the N-type doping layer 631 can be at least one of ytterbium or lithium, and when the doping material of the N-type doping layer 631 is a low work function metal salt, the doping material of the N-type doping layer 631 can be at least one of lithium carbonate and cesium carbonate.

[0048] The second electron blocking layer 65 is arranged on the side of the second hole transport layer 64 away from the first electrode 1, and the second electron blocking layer 65 includes a second electron blocking unit 651, a fourth electron blocking unit 652 and a sixth electron blocking unit 653. The thickness of the second electron blocking unit 651 is less than the thickness of the sixth electron blocking unit 653, and the thickness of the sixth electron blocking unit 653 is less than the thickness of the fourth electron blocking unit 652.

[0049] The second light-emitting material layer 4 includes a second red light-emitting unit 41, a second green light-emitting unit 42 and a second blue light-emitting unit 43. The second blue light-emitting unit 43 is arranged on the side of the second electron blocking unit 651 away from the first electrode 1, the second red light-emitting unit 41 is arranged on the side of the fourth electron blocking unit 652 away from the first electrode 1, and the second green light-emitting unit 42 is arranged on the side of the sixth electron blocking unit 653 away from the first electrode 1. The side of the second red light-emitting unit 41 away from the first electrode 1 is higher than the side of the second green light-emitting unit 42 away from the first electrode 1, and the side of the second green light-emitting unit 42 away from the first electrode 1 is higher than the side of the second blue light-emitting unit 43 away from the first electrode 1.

[0050] It should be noted that the first light-emitting material layer 3 also includes a first red light-emitting unit 31 and a first green light-emitting unit 32, the second light-emitting material layer 4 includes a second red light-emitting unit 41 and a second green light-emitting unit 42, the sum of the thicknesses of the first red light-emitting unit 31 and the second red light-emitting unit 41 is greater than or equal to the sum of the thicknesses of the first green light-emitting unit 32 and the second green light-emitting unit 42, and the sum of the thicknesses of the first green light-emitting unit 32 and the second green light-emitting unit 42 is greater than or equal to the sum of the thicknesses of the first blue light-emitting unit 33 and the second blue light-emitting unit 43.

[0051] The third light-emitting functional layer 7 includes a second hole blocking layer 71, a second electron transport layer 72 and an electron injection layer 73, wherein the second hole blocking layer 71 is arranged on the side of the second red light-emitting unit 41 away from the first electrode 1, the second electron transport layer 72 is arranged on the side of the second hole blocking layer 71 away from the first electrode 1, and the electron injection layer 73 is arranged on the side of the second electron transport layer 72 away from the first electrode 1. The second electrode 2 is arranged on the side of the electron injection layer 73 away from the first electrode 1.

[0052] The stacked light-emitting device generally includes a red stacked sub-light-emitting device 200, a green stacked sub-light-emitting device 300 and a blue stacked sub-light-emitting device 100. From the perspective of device optics, the blue stacked sub-light-emitting device 100 is a currently commonly used fluorescent light-emitting system. The blue stacked sub-light-emitting device 100 has the greatest impact on white light because the operating voltage of the blue stacked sub-light-emitting device 100 is greater than the operating voltages of the red stacked sub-light-emitting device 200 and the green stacked sub-light-emitting device 300. From the perspective of compounding into white light, improving the performance of the blue stacked sub-light-emitting device 100, especially the efficiency of the blue stacked sub-light-emitting device 100, has a more obvious improvement in white light efficiency. Therefore, in the design process of the stacked light-emitting device, special attention should be paid to the performance of the blue stacked sub-light-emitting device 100.

[0053] The first light-emitting functional layer 5 includes a first light-emitting functional portion 501, which is arranged between the first light-emitting unit and the first electrode 1, and the first light-emitting functional portion 501 is arranged between the first electrode 1 and the first blue light-emitting unit 33. The second light-emitting functional portion 601 is arranged between the first blue light-emitting unit 33 and the second blue light-emitting unit 43, and the thickness of the second light-emitting functional portion 601 is less than or equal to the thickness of the first light-emitting functional portion 501.

[0054] Since the thickness of the second light-emitting functional portion 601 is less than or equal to the thickness of the first light-emitting functional portion 501, the first light-emitting functional portion 501 has a better effect of reducing the surface plasmon effect than the second light-emitting functional portion 601, so that the improvement of the light extraction efficiency of the first blue light-emitting unit 33 close to the first electrode 1 is better than the improvement of the light extraction efficiency of the second blue light-emitting unit 43 far from the first electrode 1. In this way, the light extraction efficiencies of the first blue light-emitting unit 33 and the second blue light-emitting unit 43 can be better balanced, and the light extraction efficiencies of the first blue light-emitting unit 33 and the second blue light-emitting unit 43 are made consistent, thereby improving the light extraction efficiency of the entire blue stacked sub-light-emitting device 100, and thereby improving the power efficiency of the stacked light-emitting device.

[0055] The performance of the red stacked sub-light emitting device 200 and the green stacked sub-light emitting device 300 is improved, and the white light efficiency can also be improved. The first light-emitting functional layer 5 also includes a third light-emitting functional portion 502, which is disposed between the first red light-emitting unit 31 and the first electrode 1, and the second light-emitting functional layer 6 also includes a fourth light-emitting functional portion 602, which is disposed between the first red light-emitting unit 31 and the second red light-emitting unit 41, and the thickness of the fourth light-emitting functional portion 602 is greater than or equal to the thickness of the third light-emitting functional portion 502. The first light-emitting functional layer 5 also includes a fifth light-emitting functional portion 503, which is disposed between the first green light-emitting unit 32 and the first electrode 1, and the second light-emitting functional layer 6 also includes a sixth light-emitting functional portion 603, which is disposed between the first green light-emitting unit 32 and the second green light-emitting unit 42, and the thickness of the sixth light-emitting functional portion 603 is greater than or equal to the thickness of the fifth light-emitting functional portion 503.

[0056] For the red stacked sub-light-emitting device 200, the third light-emitting functional portion 502 has a better effect of reducing the surface plasmon effect than the fourth light-emitting functional portion 602, so that the improvement in the light extraction efficiency of the first red light-emitting unit 31 close to the first electrode 1 is better than the improvement in the light extraction efficiency of the second red light-emitting unit 41 far from the first electrode 1. In this way, the light extraction efficiencies of the first red light-emitting unit 31 and the second red light-emitting unit 41 can be better balanced, and the light extraction efficiencies of the first red light-emitting unit 31 and the second red light-emitting unit 41 can be made consistent, thereby improving the light extraction efficiency of the entire red stacked sub-light-emitting device 200 and thereby improving the power efficiency of the stacked light-emitting device.

[0057] The first light-emitting functional unit 501, the third light-emitting functional unit 502 and the fifth light-emitting functional unit 503 share the hole injection layer 51 and the first hole transport layer 52, the first electron blocking unit 531 is provided in the first light-emitting functional unit 501, the third electron blocking unit 532 is provided in the third light-emitting functional unit 502, and the fifth electron blocking unit 533 is provided in the fifth light-emitting functional unit 503. The second light-emitting functional unit 601, the fourth light-emitting functional unit 602 and the sixth light-emitting functional unit 603 share the first hole blocking layer 61, the first electron transport layer 62, the N-type doping layer 631, the P-type doping layer 632 and the second hole transport layer 64, the second electron blocking unit 651 is provided in the second light-emitting functional unit 601, the fourth electron blocking unit 652 is provided in the fourth light-emitting functional unit 602, and the sixth electron blocking unit 653 is provided in the sixth light-emitting functional unit 603.

[0058] For the blue light emitting unit, it is necessary to satisfy that the thickness of the first hole transport layer 52 is greater than or equal to the thickness of the second hole transport layer 64, so that the thickness increase of the first functional part is greater than the thickness increase of the second light emitting functional part 601. The first hole transport layer 52 and the second hole transport layer 64 use materials with different structures, the refractive index of the first hole transport layer 52 is less than the refractive index of the second hole transport layer 64, and the optical path length of the first hole transport layer 52 is greater than the optical path length of the second hole transport layer 64. Therefore, the thickness of the first hole transport layer 52 is greater than the thickness of the second hole transport layer 64, which can ensure that the first hole transport layer 52 and the second hole transport layer 64 reach the same refraction angle for the outgoing light. In this embodiment, when the wavelength of the outgoing light of the stacked light emitting device is 455-462nm, the outgoing light is in the blue light band, and the difference between the refractive index of the first hole transport layer 52 and the refractive index of the second hole transport layer 64 is greater than or equal to 0.2.

[0059] The first electron blocking unit 531 is disposed between the first hole transport layer 52 and the first blue light emitting unit 33, and the second electron blocking unit 651 is disposed between the second hole transport layer 64 and the second blue light emitting unit 43. In order to further ensure that the thickness of the first light emitting functional unit 501 is greater than the thickness of the second light emitting functional unit 601, the thickness of the first electron blocking unit 531 is set to be greater than or equal to the thickness of the second electron blocking unit 651, so that the increase in thickness of the first functional unit is greater than the increase in thickness of the second light emitting functional unit 601. When the wavelength of the output light of the stacked light emitting device is 455-462nm, the refractive index of the first electron blocking unit 531 is less than or equal to the refractive index of the second electron blocking unit 651, and the optical path length of the first electron blocking unit 531 is greater than the optical path length of the second electron blocking unit 651. Therefore, the thickness of the first electron blocking unit 531 is greater than the thickness of the second electron blocking unit 651, which can ensure that the first electron blocking unit 531 and the second electron blocking unit 651 reach the same refraction angle for the output light.

[0060] The third electron blocking unit 532 is disposed between the first hole transport layer 52 and the first red light emitting unit 31, and the fourth electron blocking unit 652 is disposed between the second hole transport layer 64 and the second red light emitting unit 41. In order to achieve that the thickness of the fourth light emitting functional unit 602 is greater than the thickness of the third light emitting functional unit 502, the thickness of the third electron blocking unit 532 is set to be less than or equal to the thickness of the fourth electron blocking unit 652. The fifth electron blocking unit 533 is disposed between the first hole transport layer 52 and the first green light emitting unit 32, and the sixth electron blocking unit 653 is disposed between the second hole transport layer 64 and the second green light emitting unit 42. The thickness of the fifth electron blocking unit 533 is less than or equal to the thickness of the sixth electron blocking unit 653.

[0061] For the blue stacked sub-light emitting device 100, in addition to setting the thickness of the first hole transport layer 52 to be greater than the thickness of the second hole transport layer 64, and the thickness of the first electron blocking unit 531 to be greater than the thickness of the second electron blocking unit 651, so that the thickness of the first light-emitting functional part 501 is greater than or equal to the thickness of the second light-emitting functional part 601, the thickness of the first blue light-emitting layer can also be set to be greater than or equal to the thickness of the second blue light-emitting layer, so that the improvement of the light extraction efficiency of the first blue light-emitting unit 33 close to the first electrode 1 is better than the improvement of the light extraction efficiency of the second blue light-emitting unit 43 far from the first electrode 1. The stacked light-emitting device of this structure can achieve a 3% increase in current efficiency, a light attenuation less than or equal to that of a single-layer blue sub-light-emitting device, and basically does not affect the service life of the light-emitting device.

[0062] In addition, for the red stacked sub-light-emitting device 200, the thickness of the first hole transport layer 52 is greater than or equal to the thickness of the second hole transport layer 64, and the thickness of the third electron blocking unit 532 is less than or equal to the thickness of the fourth electron blocking unit 652, so that the improvement of the light extraction efficiency of the first red light-emitting unit 31 close to the first electrode 1 is better than the improvement of the light extraction efficiency of the second red light-emitting unit 41 far from the first electrode 1. For the green stacked sub-light-emitting device 300, the thickness of the first hole transport layer 52 is greater than or equal to the thickness of the second hole transport layer 64, and the thickness of the fifth electron blocking unit 533 is less than or equal to the thickness of the sixth electron blocking unit 653, so that the improvement of the light extraction efficiency of the first green light-emitting unit 32 close to the first electrode 1 is better than the improvement of the light extraction efficiency of the second green light-emitting unit 42 far from the first electrode 1.

[0063] In order to make the improvement of the light extraction efficiency of the first red light emitting unit 31 close to the first electrode 1 better than the improvement of the light extraction efficiency of the second red light emitting unit 41 far from the first electrode 1, the thickness of the first red light emitting unit 31 can be set to be less than or equal to the thickness of the second red light emitting unit 41. In order to make the improvement of the light extraction efficiency of the first green light emitting unit 32 close to the first electrode 1 better than the improvement of the light extraction efficiency of the second green light emitting unit 42 far from the first electrode 1, the thickness of the first green light emitting unit 32 can be set to be less than or equal to the thickness of the second green light emitting unit 42.

[0064] The material of the first electrode 1 may be indium zinc oxide, and the chemical structure of the main material of the hole injection layer 51 is chemical structure formula 1-1:

[0065]

[0066] The organic doping material of the hole injection layer 51 is 4-[[2,3-bis[cyano-(4-cyano-2,3,5,6-tetrafluorophenyl)methyl]cyclopropyl]-cyanomethyl]-2,3,5,6-tetrafluorobenzonitrile (NDP9), and the organic doping material accounts for 3%. The chemical structure of the material of the first hole transport layer 52 is chemical structure formula 1-1, the material of the first electron blocking unit 531 is 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), and the first blue light-emitting unit 33 includes a blue light-emitting main material and a blue light-emitting doping material. The chemical structure of the blue light-emitting main material is chemical structure formula 2-1, and the chemical structure of the blue light-emitting doping material is chemical structure formula 2-2:

[0067]

[0068] The doping material ratio of the first blue light-emitting unit 33 can be 1%, the material of the first hole blocking layer 61 is 2,2",2"-(1,3,5-phenyltriylphenyl)tribenzyldiazonium (TPBI), the material of the first electron transport layer 62 is 8-hydroxyquinoline-lithium (Liq) doped with 50% in bathocuproine (BCP), the material of the N-type doping layer 631 is ytterbium (Yb) doped with 1% in bathocuproine (BCP), and the material of the P-type doping layer 632 is 2,3,5,6-tetrafluoro-7,7,8,-tetracyanodione doped with 6% in BCP. The second hole transport layer 64 has a chemical formula of 1-1, the second electron blocking unit 651 has a material of 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), the second blue light emitting unit 43 includes a blue light emitting main material and a blue light emitting doping material, the chemical formula of the blue light emitting main material is chemical formula 2-1, the chemical formula of the blue light emitting doping material is chemical formula 2-2, and the doping material ratio of the second blue light emitting unit 43 can be 1%. The material of the second hole blocking layer 71 is 2,2",2"-(1,3,5-phenyltriylphenyl)tribenzyldiazonium (TPBI), the material of the second electron transport layer 72 is 8-hydroxyquinoline-lithium (Liq) doped with 50% in bathocuproin (BCP), the material of the electron injection layer 73 is ytterbium (Yb), and the material of the second electrode 2 is a magnesium-silver mixture, and the ratio of magnesium to silver is 1:9.

[0069] In the related art, for the blue stacked sub-light-emitting device, the thickness of the hole injection layer 51 is 10nm, the thickness of the first hole transport layer 52 is 19nm, the thickness of the first electron blocking unit 531 is 5nm, the thickness of the first blue light-emitting unit 33 is 20nm, the thickness of the first hole blocking layer 61 is 5nm, the thickness of the first electron transport layer 62 is 100nm, the thickness of the N-type doping layer 631 is 15nm, the thickness of the P-type doping layer 632 is 8nm, the thickness of the second hole transport layer 64 is 21nm, the thickness of the second electron blocking unit 651 is 5nm, the thickness of the second blue light-emitting unit 43 is 20nm, the thickness of the second hole blocking layer 71 is 5nm, the thickness of the second electron transport layer 72 is 30nm, the thickness of the electron injection layer 73 is 1nm, and the thickness of the second electrode 2 is 13nm.

[0070] In this embodiment, for the blue stacked sub-light-emitting device 100, the thickness of the hole injection layer 51 is 10 nm, the thickness of the first hole transport layer 52 is 27 nm, the thickness of the first electron blocking unit 531 is 10 nm, the thickness of the first blue light-emitting unit 33 is 20 nm, the thickness of the first hole blocking layer 61 is 3 nm, the thickness of the first electron transport layer 62 is 5 nm, the thickness of the N-type doping layer 631 is 12 nm, the thickness of the P-type doping layer 632 is 7 nm, the thickness of the second hole transport layer 64 is 16 nm, the thickness of the second electron blocking unit 651 is 3 nm, the thickness of the second blue light-emitting unit 43 is 20 nm, the thickness of the second hole blocking layer 71 is 5 nm, the thickness of the second electron transport layer 72 is 30 nm, the thickness of the electron injection layer 73 is 1 nm, and the thickness of the second electrode 2 is 13 nm.

[0071] The red stacked sub-light emitting device 200 is different from the blue stacked sub-light emitting device 100 in that the thickness of the third electron blocking unit 532 is 8 nm, the thickness of the first red light emitting unit 31 is 45 nm, the thickness of the fourth electron blocking unit 652 is 26 nm, and the thickness of the second red light emitting unit 41 is 45 nm. The first red light emitting unit 31 and the second red light emitting unit 41 both include a red light emitting main material and a red light emitting doping material, and the red light emitting doping material may account for 2%. The red light emitting main material is Bebp2, and the chemical formula of the red light emitting main material is Chemical Formula 3-1, the red light emitting doping material is Ir(MDQ)2(acac), and the chemical formula of the red light emitting doping material is Chemical Formula 3-2:

[0072]

[0073] The green stacked sub-light emitting device 300 is different from the blue stacked sub-light emitting device 100 in that the thickness of the third electron blocking unit 532 is 18 nm, the thickness of the first green light emitting unit 32 is 35 nm, the thickness of the fourth electron blocking unit 652 is 43 nm, and the thickness of the second green light emitting unit 42 is 35 nm. The first green light emitting unit 32 and the second green light emitting unit 42 both include a green light emitting main material and a green light emitting doping material, and the green light emitting doping material may account for 6%. The green light emitting main material is TPBi, and the chemical formula of the green light emitting main material is chemical formula 4-1. The green light emitting doping material is Ir(ppy)3, and the chemical formula of the green light emitting doping material is chemical formula 4-2:

[0074]

[0075] for Figure 1 The blue stacked sub-light emitting device 100 in the embodiment of the present invention was verified as follows: the first hole transport layer 52 and the second hole transport material layer were set to the same material as a control group, the first hole transport layer 52 and the second hole transport material layer were set to different materials, and at 455-462nm, the difference between the refractive index S1 of the first hole transport layer 52 and the refractive index S2 of the second hole transport layer 64 was S1-S2=0.1, and at 10mA / cm 2 Under the conditions, two groups of blue stacked sub-light-emitting devices 100 were optically tested, and the test data of the blue stacked sub-light-emitting devices 100 are as follows: when S1-S2=0.1, the current efficiency is 92.2Cd / A; when S1-S2=0, the current efficiency is 89.5Cd / A. It can be seen that when the refractive index S1 of the first hole transport layer 52 is greater than the refractive index S2 of the second hole transport layer 64, the current efficiency of the blue stacked sub-light-emitting device 100 can be significantly improved. Figure 2 As shown, under the same driving voltage, when S1-S2 is 0.1, the driving voltage and brightness curve of the blue stacked sub-light-emitting device 100 is L1, and when S1-S2 is 0, the driving voltage and brightness curve of the blue stacked sub-light-emitting device 100 is L2. Obviously, under the same driving voltage, the brightness corresponding to L1 is higher than the brightness corresponding to L2.

[0076] like Figure 3 As shown, Figure 1 The difference is that a first hole blocking layer 61, a charge generating layer 63, a second hole transport layer 64 and a second electron blocking unit 651 are provided between the first blue light-emitting unit 33 and the second blue light-emitting unit 43, the thickness of the first hole transport layer 52 is greater than or equal to the thickness of the second hole transport layer 64, and the thickness of the first electron blocking unit 531 is greater than or equal to the thickness of the second electron blocking unit 651.

[0077] In addition, for the red stacked sub-light-emitting device 200, a first hole blocking layer 61, a charge generating layer 63, a second hole transport layer 64 and a fourth electron blocking unit 652 are provided between the first red light-emitting unit 31 and the second red light-emitting unit 41, the thickness of the first hole transport layer 52 is greater than or equal to the thickness of the second hole transport layer 64, and the thickness of the third electron blocking unit 532 is less than or equal to the thickness of the fourth electron blocking unit 652.

[0078] For the green stacked sub-light-emitting device 300, a first hole blocking layer 61, a charge generating layer 63, a second hole transport layer 64 and a sixth electron blocking unit 653 are provided between the first green light-emitting unit 32 and the second green light-emitting unit 42, the thickness of the first hole transport layer 52 is greater than or equal to the thickness of the second hole transport layer 64, and the thickness of the fifth electron blocking unit 533 is less than or equal to the thickness of the sixth electron blocking unit 653.

[0079] Because the first electron transport layer 62 is removed, in order to ensure the electron transport rate, it is necessary to increase the electron mobility of the first hole blocking layer 61 , that is, to set the electron mobility of the first hole blocking layer 61 greater than the electron mobility of the second hole blocking layer 71 .

[0080] The stacked light-emitting device with this structure can achieve a 2% increase in current efficiency, and the light attenuation is less than or equal to that of a single-layer blue sub-light-emitting device, and basically does not affect the service life of the light-emitting device.

[0081] In the related art, for the blue stacked sub-light-emitting device, the thickness of the hole injection layer 51 is 10nm, the thickness of the first hole transport layer 52 is 24nm, the thickness of the first electron blocking unit 531 is 5nm, the thickness of the first blue light-emitting unit 33 is 20nm, the thickness of the first hole blocking layer 61 is 5nm, the thickness of the N-type doping layer 631 is 15nm, the thickness of the P-type doping layer 632 is 8nm, the thickness of the second hole transport layer 64 is 26nm, the thickness of the second electron blocking unit 651 is 5nm, the thickness of the second blue light-emitting unit 43 is 20nm, the thickness of the second hole blocking layer 71 is 5nm, the thickness of the second electron transport layer 72 is 30nm, the thickness of the electron injection layer 73 is 1nm, and the thickness of the second electrode 2 is 13nm.

[0082] In this embodiment, for the blue stacked sub-light-emitting device 100, the thickness of the hole injection layer 51 is 10 nm, the thickness of the first hole transport layer 52 is 32 nm, the thickness of the first electron blocking unit 531 is 10 nm, the thickness of the first blue light-emitting unit 33 is 20 nm, the thickness of the first hole blocking layer 61 is 3 nm, the thickness of the N-type doping layer 631 is 12 nm, the thickness of the P-type doping layer 632 is 7 nm, the thickness of the second hole transport layer 64 is 21 nm, the thickness of the second electron blocking unit 651 is 3 nm, the thickness of the second blue light-emitting unit 43 is 20 nm, the thickness of the second hole blocking layer 71 is 5 nm, the thickness of the second electron transport layer 72 is 30 nm, the thickness of the electron injection layer 73 is 1 nm, and the thickness of the second electrode 2 is 13 nm.

[0083] for Figure 3 The blue stacked sub-light emitting device 100 in the embodiment of the present invention was verified as follows: the first hole transport layer 52 and the second hole transport material layer were set to the same material as a control group, the first hole transport layer 52 and the second hole transport material layer were set to different materials, and at 455-462nm, the difference between the refractive index S1 of the first hole transport layer 52 and the refractive index S2 of the second hole transport layer 64 was S1-S2=0.1, and at 10mA / cm 2 Under the conditions, two groups of blue stacked sub-light-emitting devices 100 were optically tested, and the test data of the blue stacked sub-light-emitting devices 100 are as follows: when S1-S2=0.1, the current efficiency is 86.9Cd / A; when S1-S2=0, the current efficiency is 85.1Cd / A. It can be seen that when the refractive index S1 of the first hole transport layer 52 is greater than the refractive index S2 of the second hole transport layer 64, the current efficiency of the blue stacked sub-light-emitting device 100 can be significantly improved. Figure 4 As shown, under the same driving voltage, when S1-S2=0.1, the driving voltage and brightness relationship curve of the blue stacked sub-light-emitting device 100 is L4, and when S1-S2 is 0, the driving voltage and brightness relationship curve of the blue stacked sub-light-emitting device 100 is L3. Obviously, under the same driving voltage, the brightness corresponding to L4 is higher than the brightness corresponding to L3.

[0084] When the electron mobility of the first hole blocking layer 61 is set to be greater than the electron mobility of the second hole blocking layer 71 , the material of the first hole blocking layer 61 is 4,7-diphenyl-1,10-phenanthroline (Bphen).

[0085] Two groups of blue stacked light-emitting devices were set up, and optical tests were performed on the two groups of blue stacked sub-light-emitting devices 100 under the condition of 10 mA / cm2. In the first group of blue stacked light-emitting devices, when the material of the first hole blocking layer 61 is 4,7-diphenyl-1,10-phenanthroline (Bphen), the material of the second hole blocking layer 71 is 2,2",2"-(1,3,5-phenyltriylphenyl)tribenzyldiazonium (TPBI); in the second group of blue stacked light-emitting devices, the material of the first hole blocking layer 61 is 2,2",2"-(1,3,5-phenyltriylphenyl)tribenzyldiazonium (TPBI), and the material of the second hole blocking layer 71 is 2,2",2"-(1,3,5-phenyltriylphenyl)tribenzyldiazonium (TPBI).

[0086] The specific test data are as follows: when the material of the first hole blocking layer 61 is 2,2",2"-(1,3,5-phenyltriylphenyl)tribenzyldiazonium (TPBI), the voltage is 9.32V and the current efficiency is 86.9Cd / A; when the material of the first hole blocking layer 61 is 4,7-diphenyl-1,10-phenanthroline (Bphen), the voltage is 9.21V and the current efficiency is 87.8Cd / A. The first group of blue stacked light-emitting devices can achieve a 1% reduction in operating voltage and a 1% increase in current efficiency.

[0087] The embodiment of the present disclosure also provides a display module, and the display device may include the flexible circuit board mentioned in the embodiment of the present disclosure. The specific structure and beneficial effects of the display module can refer to the flexible circuit board, and the specific structure and beneficial effects of the flexible circuit board have been described in detail above, so they will not be repeated here.

[0088] The present disclosure also provides a display panel, which may include the laminated light emitting device mentioned in the present disclosure. The structure and beneficial effects of the display panel can refer to the laminated light emitting device, and the specific structure and beneficial effects of the laminated light emitting device have been described in detail above, so they will not be repeated here.

[0089] The present disclosure also provides a display device, which may include the display panel mentioned in the present disclosure. The structure and beneficial effects of the display device can refer to the display panel, and the specific structure and beneficial effects of the display panel can refer to the stacked light-emitting device, so it will not be repeated here.

[0090] It should be noted that, in addition to the display panel, the display device also includes other necessary components and components, such as a housing, a circuit board, a power cord, etc. Those skilled in the art may make corresponding supplements according to the specific use requirements of the display device, which will not be repeated here.

[0091] The display device can be a traditional electronic device, such as a mobile phone, a computer, a television, and a camcorder, or it can be an emerging wearable device, such as a virtual reality device and an augmented reality device, which are not listed here one by one.

[0092] It should be noted that the above embodiments are interoperable and can be combined with each other to form other schemes, and the scheme of the present disclosure is not limited to the schemes described in the above embodiments. After considering the specification and practicing the invention disclosed herein, those skilled in the art will easily think of other embodiments of the present disclosure. This application is intended to cover any modification, use or adaptive change of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field that are not disclosed in the present disclosure. The description and embodiments are to be regarded as exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A stacked light emitting device, characterized in that: include: a first electrode; a second electrode, arranged opposite to the first electrode; A first light-emitting material layer, disposed between the first electrode and the second electrode, wherein the first light-emitting material layer includes a first blue light-emitting unit; A second light-emitting material layer, disposed between the first light-emitting material layer and the second electrode, the second light-emitting material layer comprising a second blue light unit; A first light-emitting functional layer, comprising a first light-emitting functional portion, wherein the first light-emitting functional portion is disposed between the first blue light-emitting unit and the first electrode; The second light-emitting functional layer includes a second light-emitting functional portion, wherein the second light-emitting functional portion is disposed between the first blue light-emitting unit and the second blue light-emitting unit, and a thickness of the second light-emitting functional portion is less than or equal to a thickness of the first light-emitting functional portion.

2. The stacked light emitting device according to claim 1, characterized in that: The thickness of the first blue light emitting unit is greater than or equal to the thickness of the second blue light emitting unit.

3. The stacked light emitting device according to claim 2, characterized in that: The first light-emitting material layer also includes a first red light-emitting unit, the second light-emitting material layer includes a second red light-emitting unit, the first light-emitting functional layer also includes a third light-emitting functional portion, the third light-emitting functional portion is arranged between the first red light-emitting unit and the first electrode, the second light-emitting functional layer also includes a fourth light-emitting functional portion, the fourth light-emitting functional portion is arranged between the first red light-emitting unit and the second red light-emitting unit, and the thickness of the fourth light-emitting functional portion is greater than or equal to the thickness of the third light-emitting functional portion.

4. The stacked light emitting device according to claim 3, characterized in that: The first light-emitting material layer also includes a first green light-emitting unit, the second light-emitting material layer also includes a second green light-emitting unit, the first light-emitting functional layer also includes a fifth light-emitting functional portion, the fifth light-emitting functional portion is arranged between the first green light-emitting unit and the first electrode, the second light-emitting functional layer also includes a sixth light-emitting functional portion, the fourth light-emitting functional portion is arranged between the first green light-emitting unit and the second green light-emitting unit, and the thickness of the sixth light-emitting functional portion is greater than or equal to the thickness of the fifth light-emitting functional portion.

5. The stacked light emitting device according to claim 4, characterized in that: A first hole transport layer is provided on a side of the first light-emitting functional unit, the third light-emitting functional unit and the fifth light-emitting functional unit close to the first electrode, and a second hole transport layer is provided on a side of the second light-emitting functional unit, the fourth light-emitting functional unit and the sixth light-emitting functional unit close to the first electrode, and a thickness of the first hole transport layer is greater than or equal to a thickness of the second hole transport layer.

6. The stacked light emitting device according to claim 5, characterized in that: The refractive index of the first hole transport layer is smaller than the refractive index of the second hole transport layer.

7. The stacked light emitting device according to claim 6, characterized in that: When the wavelength of the output light of the stacked light emitting device is 455-462 nm, the difference between the refractive index of the first hole transport layer and the refractive index of the second hole transport layer is greater than or equal to 0.

2.

8. The stacked light emitting device according to claim 5, characterized in that: The first light-emitting functional portion includes a first electron blocking unit, and the second light-emitting functional portion includes a second electron blocking unit. The first electron blocking unit is arranged between the first hole transport layer and the first blue light-emitting unit, and the second electron blocking unit is arranged between the second hole transport layer and the second blue light-emitting unit. The thickness of the first electron blocking unit is greater than or equal to the thickness of the second electron blocking unit.

9. The stacked light emitting device according to claim 8, characterized in that: The third light-emitting functional portion includes a third electron blocking element, and the fourth light-emitting functional portion includes a fourth electron blocking unit. The third electron blocking unit is arranged between the first hole transport layer and the first red light-emitting unit, and the fourth electron blocking unit is arranged between the second hole transport layer and the second red light-emitting unit. The thickness of the third electron blocking unit is less than or equal to the thickness of the fourth electron blocking unit.

10. The stacked light emitting device according to claim 9, characterized in that: The fifth light-emitting functional portion includes a fifth electron blocking unit, and the sixth light-emitting functional portion includes a sixth electron blocking unit. The fifth electron blocking unit is arranged between the first hole transport layer and the first green light-emitting unit, and the sixth electron blocking unit is arranged between the second hole transport layer and the second green light-emitting unit. The thickness of the fifth electron blocking unit is less than or equal to the thickness of the sixth electron blocking unit.

11. The stacked light emitting device according to claim 8, characterized in that: When the wavelength of the output light of the stacked light emitting device is 455-462 nm, the refractive index of the first electron blocking unit is less than or equal to the refractive index of the second electron blocking unit.

12. The stacked light emitting device according to claim 10, characterized in that: The second light-emitting functional layer includes a first hole blocking layer, a first electron transport layer and a charge generating layer, wherein the charge generating layer is arranged between the first light-emitting material layer and the second hole transport layer, the charge generating layer includes an N-type doped layer and a P-type doped layer, the P-type doped layer is arranged on a side of the N-type doped layer away from the first light-emitting material layer, the first electron transport layer is arranged on a side of the N-type doped layer close to the first light-emitting material layer, the first hole blocking layer is arranged on a side of the first electron transport layer close to the first light-emitting material layer, the stacked light-emitting device also includes a third light-emitting functional layer, the third light-emitting functional layer includes a second hole blocking layer, the second hole blocking layer is arranged on a side of the second light-emitting material layer away from the first electrode, and the electron mobility of the first hole blocking layer is equal to the electron mobility of the second hole blocking layer.

13. The stacked light emitting device according to claim 10, characterized in that: The second light-emitting functional layer includes a first hole blocking layer and a charge generating layer, the charge generating layer is arranged between the first light-emitting material layer and the second hole transport layer, the charge generating layer includes an N-type doped layer and a P-type doped layer, the P-type doped layer is arranged on the side of the N-type doped layer away from the first light-emitting material layer, and the first hole blocking layer is arranged on the side of the N-type doped layer close to the first light-emitting material layer, the third light-emitting functional layer includes a second hole blocking layer, and the second hole blocking layer is arranged on the side of the second light-emitting material layer away from the first electrode, the stacked light-emitting device also includes a third light-emitting functional layer, the third light-emitting functional layer includes a second hole blocking layer, and the second hole blocking layer is arranged on the side of the second light-emitting material layer away from the first electrode, and the electron mobility of the first hole blocking layer is greater than the electron mobility of the second hole blocking layer.

14. The stacked light emitting device according to claim 4, characterized in that: The first light-emitting material layer also includes a first red light-emitting unit and a first green light-emitting unit, the second light-emitting material layer includes a second red light-emitting unit and a second green light-emitting unit, the sum of the thicknesses of the first red light-emitting unit and the second red light-emitting unit is greater than or equal to the sum of the thicknesses of the first green light-emitting unit and the second green light-emitting unit, and the sum of the thicknesses of the first green light-emitting unit and the second green light-emitting unit is greater than or equal to the sum of the thicknesses of the first blue light-emitting unit and the second blue light-emitting unit.

15. The stacked light emitting device according to claim 12 or 13, characterized in that: The doping material of the N-type doping layer is a low work function metal or a low work function metal salt, and the doping concentration of the N-type doping layer is in the range of 1.2%±0.8%. The doping material of the P-type doping layer is an organic electronic material or an inorganic metal oxide material, and the doping concentration of the P-type doping layer is in the range of 10%±5%.

16. A display panel, characterized in that: A stacked light emitting device comprising any one of claims 1 to 15.

17. A display device, characterized in that: Includes the display panel as claimed in claim 16.

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