Laminated OLED device

Abstract

The utility model provides a laminated OLED device. The laminated OLED device comprises an anode layer; the at least two light-emitting structure layers are arranged on the anode layer in a stacked mode, each light-emitting structure layer comprises a hole transport layer, a light-emitting layer and an electron transport layer, and each light-emitting layer is arranged between the adjacent hole transport layer and the electron transport layer; each charge generation layer is arranged between every two adjacent light-emitting structure layers, and each charge generation layer comprises an N-type electron generation layer, a middle layer and a P-type hole generation layer which are sequentially arranged in a stacked mode; the cathode layer is arranged on one side, deviating from the anode layer, of the at least two light-emitting structure layers; the refractive index of the P-type hole generation layer is larger than that of the middle layer, and the difference value between the two is smaller than or equal to 0.3; the refractive index of the N-type electron generation layer is larger than that of the middle layer, and the difference between the refractive index and the refractive index is smaller than or equal to 0.4. According to the laminated OLED device provided by the utility model, the reflection of interfaces among the charge generation layers is reduced, and the efficiency of the device is high.

Description

Technical Field

[0001] The utility model relates to the technical field related to display panels, and in particular to a laminated OLED device. Background Art

[0002] Organic Light Emitting Diode (OLED) is a new generation of display technology that has developed rapidly in recent years. It has the advantages of self-luminescence, fast response, high luminous efficiency and brightness, ultra-thinness, wide viewing angle, wide operating temperature range, simple production process, low power consumption and flexibility. It is widely used in many fields such as flat panel displays, flexible displays, automotive displays and solid-state lighting.

[0003] With the continuous development of OLED technology, people gradually found that if a single-layer OLED device wants to achieve high brightness, it will cause a surge in heat due to excessive driving current, thereby reducing the performance and service life of the device. Therefore, achieving high luminous brightness and efficiency at a lower current density and improving the service life of the device are key factors in realizing the industrialization of OLED. The concept of stacked OLED was first proposed by Professor Junji Kido of Yamagata University in Japan in 2003. By connecting at least two OLED units in series through a charge generation layer, higher luminous brightness and current efficiency can be obtained; at the same time, when measured at the same current density, the aging properties of the stacked OLED device and the OLED unit are the same, but because the initial brightness of the stacked OLED is large, when converted to the same initial brightness, the life of the stacked OLED device will be significantly higher than that of the OLED unit. Therefore, it is a consensus in this field that a stacked OLED device can be used to obtain better luminous performance and longer service life.

[0004] It should be noted that the information of the utility model in the above background technology section is only used to enhance the understanding of the background of the utility model, and therefore may include information that does not constitute the prior art known to those skilled in the art. Utility Model Content

[0005] In view of the problems in the prior art, the purpose of the present invention is to provide a stacked OLED device. By setting the refractive index difference and K value between the N-type electron generation layer, the intermediate layer and the P-type hole generation layer of the charge generation layer, the reflection at the interface of each layer is reduced, the light loss is reduced, the transmittance is improved, and the efficiency of the device is improved.

[0006] The embodiment of the utility model provides a stacked OLED device, comprising:

[0007] Anode layer;

[0008] At least two light-emitting structure layers, at least two of which are stacked on the anode layer, the light-emitting structure layers comprising a hole transport layer, a light-emitting layer, and an electron transport layer, the light-emitting layer being disposed between adjacent hole transport layers and adjacent electron transport layers;

[0009] at least one charge generation layer, each of which is disposed between two adjacent light-emitting structure layers, and the charge generation layer comprises an N-type electron generation layer, an intermediate layer and a P-type hole generation layer which are stacked in sequence; and

[0010] A cathode layer, disposed on a side of at least two of the light-emitting structure layers away from the anode layer;

[0011] The refractive index of the P-type hole generating layer is greater than the refractive index of the intermediate layer, and the difference between the two is less than or equal to 0.3;

[0012] The refractive index of the N-type electron generating layer is greater than the refractive index of the intermediate layer, and the difference between the refractive index and the N-type electron generating layer is less than or equal to 0.4.

[0013] According to some examples of the present invention, the refractive index of the N-type electron generation layer is in the range of 1.5-1.9.

[0014] According to some examples of the present invention, the refractive index of the P-type hole generating layer is in the range of 1.4-2.0.

[0015] According to some examples of the present invention, the refractive index of the intermediate layer is less than 1.6.

[0016] According to some examples of the present invention, an absolute value of a difference between an extinction ratio of the intermediate layer and an extinction ratio of the N-type electron generation layer is less than or equal to 0.01.

[0017] According to some examples of the present invention, the absolute value of the difference between the extinction ratio of the intermediate layer and the extinction ratio of the P-type hole generating layer is less than or equal to 0.01.

[0018] The charge generation layer of the stacked OLED device of the utility model includes an N-type electron generation layer, an intermediate layer and a P-type hole generation layer. By setting the refractive index difference and K value between the N-type electron generation layer, the intermediate layer and the P-type hole generation layer, the reflection of the interface between the three is reduced, so as to reduce light loss, improve transmittance and thus improve the efficiency of the device and reduce device power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other features and advantages of the present application will become more apparent by describing in detail example embodiments thereof with reference to the attached drawings.

[0020] Figure 1It is a schematic structural diagram of a stacked OLED device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following describes the implementation of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed by the present invention. The present invention can also be implemented or applied through other different specific implementations, and the details in the present invention can also be modified or changed according to different viewpoints and application systems without departing from the spirit of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0022] The following is a detailed description of the embodiments of the present invention with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. The present invention can be embodied in a variety of different forms and is not limited to the embodiments described herein.

[0023] In the description of the present invention, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics represented in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials or characteristics represented may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples represented in the present invention and the features of different embodiments or examples, unless they are contradictory.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the representation of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0025] In order to clearly describe the present invention, components irrelevant to the description are omitted, and the same or similar components throughout the specification are given the same reference symbols.

[0026] Throughout the specification, when a device is said to be "connected" to another device, this includes not only the case of "direct connection" but also the case of "indirect connection" by placing other elements therebetween. In addition, when a device is said to "include" a certain component, unless otherwise stated, it does not exclude other components, but means that other components may be included.

[0027] When a device is said to be "on" another device, it may be directly on the other device, but there may also be other devices between it. In contrast, when a device is said to be "directly" on another device, there are no other devices between it.

[0028] Although the terms first, second, etc. are used to represent various elements in some examples, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, the first interface and the second interface, etc. are represented. Moreover, as used in this article, the singular forms "one", "one" and "the" are intended to also include plural forms, unless there is an opposite indication in the context. It should be further understood that the terms "comprising" and "including" indicate the existence of features, steps, operations, elements, components, projects, kinds, and / or groups, but do not exclude the existence, occurrence or addition of one or more other features, steps, operations, elements, components, projects, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Only when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way, will there be an exception to this definition.

[0029] The technical terms used herein are only used to refer to specific embodiments and are not intended to limit the present invention. The singular form used herein also includes the plural form as long as the sentence does not clearly indicate the opposite meaning. The meaning of "including" used in the specification is to specify specific characteristics, regions, integers, steps, operations, elements and / or components, and does not exclude the existence or addition of other characteristics, regions, integers, steps, operations, elements and / or components.

[0030] Although not defined differently, all terms, including technical and scientific terms used herein, have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with the content of relevant technical literature and current prompts, and as long as they are not defined, they shall not be overly interpreted as ideal or very formal meanings.

[0031] In order to overcome the above technical problems, the utility model provides a stacked OLED device, comprising: an anode layer; at least two light-emitting structure layers, at least two of the light-emitting structure layers are stacked on the anode layer, the light-emitting structure layer comprises a hole transport layer, a light-emitting layer, and an electron transport layer, and the light-emitting layer is arranged between adjacent hole transport layers and electron transport layers; at least one charge generation layer, each of the charge generation layers is arranged between two adjacent light-emitting structure layers, and the charge generation layer comprises an N-type electron generation layer, an intermediate layer and a P-type hole generation layer stacked in sequence; and a cathode layer, which is arranged on the side of at least two of the light-emitting structure layers away from the anode layer; the refractive index of the P-type hole generation layer is greater than the refractive index of the intermediate layer and the difference between the two is less than or equal to 0.3; the refractive index of the N-type electron generation layer is greater than the refractive index of the intermediate layer and the difference between the two is less than or equal to 0.4. The charge generation layer of the stacked OLED device of the utility model includes an N-type electron generation layer, an intermediate layer and a P-type hole generation layer. By setting the refractive index difference and K value between the N-type electron generation layer, the intermediate layer and the P-type hole generation layer, the reflection of the interface between the three is reduced, so as to reduce light loss, improve transmittance and thus improve the efficiency of the device and reduce device power consumption.

[0032] The structure of the stacked OLED device of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the various specific embodiments are not intended to limit the protection scope of the present invention.

[0033] Figure 1 This is a schematic structural diagram of a stacked OLED device according to an embodiment of the present invention. Specifically, the stacked OLED device includes:

[0034] The anode layer 10 may be a transparent metal oxide layer including, for example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and indium tin zinc oxide (ITZO).

[0035] At least two light emitting structure layers, at least two of the light emitting structure layers are stacked on the first electrode layer. It can be understood that the at least two light emitting structure layers refer to the number of the light emitting structure layers being N, and N≥2. Figure 1 In the embodiment of the present invention, the stacked OLED device includes two light-emitting structure layers, namely, light-emitting structure layer 2A, light-emitting structure layer 2B and light-emitting structure layer 2C. In fact, there can also be two or more light-emitting layers, that is, multiple light-emitting units can be used in the device of the present invention. Each of the light-emitting structure layers 2A / 2B may include a hole transport layer, a light-emitting layer, and an electron transport layer, and the light-emitting layer is arranged between the adjacent hole transport layer and the electron transport layer;

[0036] At least one charge generation layer, each charge generation layer is arranged between two adjacent light emitting structure layers, that is, the charge generation layer of the present application is used as a connecting layer between each two adjacent light emitting structure layers. The stacked OLED device of the present utility model is provided with N-1 charge generation layers. Figure 1 The stacked OLED device in the embodiment includes two light emitting structure layers, and accordingly, the stacked OLED device includes a charge generation layer 3. Each charge generation layer 3 includes an N-type electron generation layer 31, an intermediate layer 32 and a P-type hole generation layer 33 which are stacked in sequence.

[0037] The N-type electron generating layer 31 of the utility model can be 4,7-diphenyl-1,10-phenanthroline (Bphen); 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), also known as basolin 4,7-diphenyl-1,10-phenanthroline (C24H16N2), tris (8-hydroxyquinolinato) aluminum (Tris (8-hydroxyquinolinato) aluminum, Alq3), 7,7,8,8-tetracyanoquinodimethane (Tetracyanoquinodimethane, F4-TCN Q), fluorine-substituted copper phthalocyanine (F16CuPc), ZnPc phthalocyanine zinc 1,4,5,8,9,11-hexaazatriphenylhexanitrile (HATCN), etc., but not limited to them. The doping metal of the N-type electron generation layer can be potassium (K), sodium (Na), magnesium (Mg), niobium (Yb) or ytterbium (Nb). The N-type electron generation layer 31 can be prepared by line source evaporation. Line source evaporation can improve the uniformity of large-area evaporation film formation. At the same time, the temperature of the line source evaporation preparation temperature can be controlled. For example, the line source evaporation temperature is less than 500°C, which can improve the quality of the organic film layer, increase the evaporation rate, and control the composition and thickness of the organic film layer. Preferably, the thickness of the N-type electron generation layer 31 is between 50 angstroms and 200 angstroms.

[0038] The intermediate layer 32 may be a metal layer or alloy layer formed of silver, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, zinc, cadmium, gallium, thallium, silicon, germanium, etc. The thickness of the intermediate layer 32 is between 5 angstroms and 20 angstroms.

[0039] The P-type hole generating layer 33 can be F4-TCNQ, TPBI, NPB, m-MTDATA, 2-TNATA, PTCDA, TCTA, F16CuPc or CuPc, etc., wherein F4-TCNQ is 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane; TPBI is 2,2',2"-(1,3,5-benzenetriyl)-tri(1-phenyl-1-h-benzimidazole); NPB is N,N'-di(naphthalene-1-yl)-N,N'-di(phenyl)-benzidine; m-MTDATA is 4,4',4"-tris(N-3-methoxy)-1,4-diphenylamine; thylphenyl-N-phenyl-amino) triphenylamine; 2-TNATA is 4,4',"tri(N-(naphthalen-2-yl)-N-phenyl-amino) triphenylamine; PTCDA is 3,4,9,10-perylenetetracarboxylic dianhydride; TCTA is 4,4',4"-tri(carbazol-9-yl) triphenylamine; F16CuPc is copper (II) 1, 2, 3, 4, 8, 9, 10, 11, 15, 16, 17, 18, 22, 23, 24, 25-hexafluoro-29h, 31phthalocyanine; CuPc is copper (II) phthalocyanine. The thickness of the P-type hole generating layer 33 can be between 40 angstroms and 200 angstroms. The cathode layer 90 is arranged on the side of at least two of the light-emitting structure layers away from the anode layer 10. Of course, the stacked OLED device of the utility model can also include a light extraction layer on the light-emitting side, which is not elaborated here.

[0040] In the present invention, the refractive index of the P-type hole generation layer 33 is greater than the refractive index of the intermediate layer 32, and the difference between the two is less than or equal to 0.3; the refractive index of the N-type electron generation layer 31 is greater than the refractive index of the intermediate layer 32, and the difference between the two is less than or equal to 0.4. The refractive index n value of each functional layer of the stacked OLED device determines the propagation speed of light in the functional layer. The higher the refractive index, the slower the propagation speed of light in the functional layer. The extinction ratio k value represents the absorption coefficient of the functional layer for light of a specific wavelength. The higher the absorption coefficient, the stronger the absorption capacity of the functional layer for light of a specific wavelength. In the present invention, the refractive index of the intermediate layer 32 is less than the refractive index of the P-type hole generation layer 33 and the N-type electron generation layer 31, that is, the refractive index of the N-type electron generation layer 31, the intermediate layer 32 and the P-type hole generation layer 33 first decreases and then increases.

[0041] Preferably, the refractive index of the N-type electron generation layer 31 is in the range of 1.5-1.9, the refractive index of the P-type hole generation layer 33 is in the range of 1.4-2.0, and the refractive index of the intermediate layer 32 is less than 1.6.

[0042] Table 1 shows the low grayscale blue device efficiency (BI) of the comparative example and two embodiments of the utility model. Among them, the N-type electron generation layer of the comparative example is Alq3, with a refractive index of 1.7; the intermediate layer is zinc, with a refractive index of 2; and the P-type hole generation layer is CuPc, with a refractive index of 1.7. The N-type electron generation layer of Example 1 is Alq3, with a refractive index of 1.7; the intermediate layer is copper, with a refractive index of 1.39; and the P-type hole generation layer is F4-TCNQ, with a refractive index of 1.52. The N-type electron generation layer of Example 2 is Bplen, with a refractive index of 1.71; the intermediate layer is copper, with a refractive index of 1.39; and the P-type hole generation layer is NPB, with a refractive index of 1.43.

[0043] Table 1 shows the low grayscale blue device efficiency (BI) of the comparative example and two embodiments of the present invention.

[0044] N value N-type electron generation layer Middle Layer P-type hole generating layer Blue device efficiency (BI) Comparative Example 1.7 2 1.7 250 Example 1 1.7 1.39 1.52 290 Example 2 1.71 1.39 1.43 350

[0045] It can be seen from Table 1 that the low grayscale blue device efficiency of the stacked OLED device of the present invention is higher than the low grayscale blue device efficiency of the comparative example.

[0046] In addition, the optical nk value of each functional layer is the product of the refractive index n and the extinction ratio k value. The refractive index n and the extinction ratio k value of the N-type electron generation layer 31, the intermediate layer 32 and the P-type hole generation layer 33 can be further determined according to the structure of the stacked OLED device to obtain the best optical performance, thereby reducing the light loss on each interface in the charge generation layer 3, improving the efficiency of the device, and reducing the power consumption of the device. Preferably, the absolute value of the difference between the extinction ratio of the intermediate layer 32 and the extinction ratio of the N-type electron generation layer 31 is less than or equal to 0.01; the absolute value of the difference between the extinction ratio of the intermediate layer 32 and the extinction ratio of the P-type hole generation layer 33 is less than or equal to 0.01.

[0047] By designing the device structure and selecting the charge generation layer material, the refractive index and extinction ratio k value of the N-type electron generation layer 31, the intermediate layer 32 and the P-type hole generation layer 33 meet the above settings, so that the reflection of light at the interface in the charge generation layer is reduced to reduce light loss. The reflectivity between the interfaces is reduced, the transmittance is increased, and the device efficiency is improved.

[0048] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

[0049] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A stacked OLED device, characterized in that: include: Anode layer; At least two light-emitting structure layers, at least two of which are stacked on the anode layer, the light-emitting structure layers comprising a hole transport layer, a light-emitting layer, and an electron transport layer, the light-emitting layer being disposed between adjacent hole transport layers and adjacent electron transport layers; at least one charge generation layer, each of which is disposed between two adjacent light-emitting structure layers, and the charge generation layer comprises an N-type electron generation layer, an intermediate layer and a P-type hole generation layer which are stacked in sequence; and A cathode layer, disposed on a side of at least two of the light-emitting structure layers away from the anode layer; The refractive index of the P-type hole generating layer is greater than the refractive index of the intermediate layer, and the difference between the two is less than or equal to 0.3; The refractive index of the N-type electron generating layer is greater than the refractive index of the intermediate layer, and the difference between the refractive index and the N-type electron generating layer is less than or equal to 0.

4.

2. The stacked OLED device according to claim 1, characterized in that: The refractive index of the N-type electron generating layer is in the range of 1.5-1.

9.

3. The stacked OLED device according to claim 1, characterized in that: The refractive index of the P-type hole generating layer is in the range of 1.4-2.

0.

4. The stacked OLED device according to claim 1, characterized in that: The refractive index of the intermediate layer is less than 1.

6.

5. The stacked OLED device according to claim 1, characterized in that: An absolute value of a difference between an extinction ratio of the intermediate layer and an extinction ratio of the N-type electron generation layer is less than or equal to 0.

01.

6. The stacked OLED device according to claim 1, characterized in that: An absolute value of a difference between an extinction ratio of the intermediate layer and an extinction ratio of the P-type hole generating layer is less than or equal to 0.01.

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