Organic Light Emitting Diodes

Abstract

The technology described in the present invention relates to an organic light emitting diode, comprising: a first electrode; a second electrode overlapping the first electrode; an organic light emitting layer between the first electrode and the second electrode; and a covering layer on the second electrode, wherein the covering layer has an absorptivity of 0.25 or greater for light with a wavelength of 405 nm, thereby preventing degradation of the organic light emitting layer by blocking light in a harmful wavelength region, and providing an organic light emitting diode in which blue light emitting efficiency is not deteriorated.

Description

[0001] This application is a divisional application of the invention patent application with the application date of April 7, 2017, application number 201710224996.8, and invention name “Organic Light Emitting Diode”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to and the benefit of Korean Patent Application No. 10-2016-0042916, filed on April 7, 2016, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0004] The present disclosure relates to organic light emitting diodes and, more particularly, to organic light emitting diodes that perceive minimal damage from harmful wavelengths of radiation. Background Art

[0005] Recently, display devices including organic light emitting diodes have become increasingly popular. As more people use display devices including organic light emitting diodes, display devices are used in a wider range of environments than before.

[0006] However, in a display device including an organic light emitting diode, the organic light emitting layer is easily damaged by environmental elements. This results in an undesirably short product life. A display device that can be used in various environments and provides excellent light efficiency without being easily damaged by environmental elements is needed.

[0007] The above information disclosed in this Background section is for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. Summary of the invention

[0008] Example embodiments provide an organic light emitting diode that is prevented from being degraded by harmful wavelengths.

[0009] An organic light emitting diode according to an exemplary embodiment of the described technology includes: a first electrode; a second electrode overlapping the first electrode; an organic light emitting layer between the first electrode and the second electrode; and a covering layer on the second electrode, wherein the covering layer has an absorptivity of 0.25 or more for light having a wavelength of 405 nm.

[0010] The cover layer may have an absorptivity of less than 0.25 at a wavelength of 430 nm.

[0011] The overlay can meet the following conditions:

[0012] k 1 -k 2 >0.10

[0013] where k 1 is the absorbance at 405 nm, and k 2 is the absorbance at 430nm wavelength.

[0014] The cover layer may have a refractive index of 2.0 or more in a wavelength range of 430 nm to 470 nm.

[0015] The organic light emitting layer may include a blue light emitting layer, and a light emitting spectrum peak wavelength of a blue light emitting material included in the blue light emitting layer may be 430 nm to 500 nm.

[0016] The second electrode may have a light transmittance of 20% or more in a wavelength range of 430 nm to 500 nm.

[0017] The organic light emitting layer may include a blue light emitting layer, a red light emitting layer, and a green light emitting layer, and the cover layer may overlap the blue light emitting layer, the red light emitting layer, and the green light emitting layer, respectively.

[0018] The covering layer may include carbon atoms and hydrogen atoms, and may include at least one selected from the group consisting of aromatic hydrocarbon compounds, aromatic heterocyclic compounds and amine compounds, wherein the aromatic hydrocarbon compounds, aromatic heterocyclic compounds and amine compounds include substituents having at least one of the group consisting of oxygen atoms, sulfur atoms, nitrogen atoms, fluorine atoms, silicon atoms, chlorine atoms, bromine atoms and iodine atoms.

[0019] The capping layer may have a thickness of 200 nm or less.

[0020] The cover layer may have an absorptivity of 1.0 or less at a wavelength of 405 nm.

[0021] The cover layer may block 50% or more of light at a wavelength of 405 nm.

[0022] The organic light emitting layer may be combined with multiple layers representing different colors to emit white light.

[0023] The plurality of layers may include a structure in which 2 layers or 3 layers are deposited.

[0024] According to the exemplary embodiments, by blocking light in a harmful wavelength region, degradation of the organic light emitting layer may be prevented, and blue light emission efficiency of the organic light emitting diode may not be deteriorated. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FIG. 1 is a view schematically showing a structure of an organic light emitting diode according to an exemplary embodiment of the technology described herein.

[0026] Figure 2FIG. 1 is a view schematically showing a structure of an organic light emitting diode according to another exemplary embodiment of the technology described herein.

[0027] Figure 3 Graphs showing the absorptivity, refractive index, transmittance, and sunlight spectrum of the cover material corresponding to Exemplary Embodiment 1.

[0028] Figure 4 Graph showing the absorptivity, refractive index, transmittance and sunlight spectrum of the cover material corresponding to Comparative Example 1.

[0029] <Description of symbols>

[0030] 110: First electrode

[0031] 120: Second electrode

[0032] 130R: Red light emitting layer

[0033] 130R': Red resonance auxiliary layer

[0034] 130G: Green light emitting layer

[0035] 130G': Green resonance auxiliary layer

[0036] 130B: Blue light emitting layer

[0037] BIL: auxiliary layer

[0038] 140: Overlay

[0039] 150: Pixel limiting layer

[0040] 160: Hole transport layer

[0041] 170: Electron transport layer DETAILED DESCRIPTION

[0042] The described technology will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. As those skilled in the art will appreciate, the described embodiments can be modified in various different ways without departing from the spirit or scope of the described technology.

[0043] In order to clearly explain the described technology, aspects or portions that are not directly related to the described technology are omitted, and the same reference numerals are attached to the same or similar constituent elements throughout the entire specification.

[0044] In addition, for better understanding and ease of description, the size and thickness of each configuration shown in the drawings are arbitrarily shown, and the described technology is not limited thereto. In the drawings, the thickness of layers, films, plates, regions, etc. are exaggerated for clarity. In the drawings, the thickness of some layers and regions may be exaggerated for better understanding and ease of description.

[0045] It should be understood that when an element such as a layer, film, region or substrate is referred to as being "on" another element, it can be directly on the other element, or there can be an intervening element. Conversely, when an element is referred to as being "directly on" another element, there are no intervening elements. In addition, in this specification, the words "on..." or "above..." mean to be placed above or below an object part, and do not necessarily mean to be placed on the upper side of the object part based on the direction of gravity.

[0046] In addition, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

[0047] In addition, in this specification, the phrase "on a plane" means observing a part of an object from the top, and the phrase "on a cross section" means observing a part of an object cut vertically from the side.

[0048] Figure 1 FIG. 2 is a view schematically showing the structure of an organic light emitting diode according to the present exemplary embodiment. Figure 1 As shown, the organic light emitting diode according to the present exemplary embodiment includes a first electrode 110 , a second electrode 120 , an organic light emitting layer 130 , and a capping layer 140 .

[0049] The first electrode 110 is formed on the substrate and may function as an anode to emit electrons into the organic light emitting layer 130. However, the first electrode 110 is not limited thereto, and may be a cathode when the second electrode 120 functions as an anode.

[0050] The organic light emitting diode according to the present exemplary embodiment may be a top emission organic light emitting diode. Therefore, the first electrode 110 may be used as a reflective layer that does not emit light emitted from the organic light emitting layer 130 to the rear surface. Here, the reflective layer means a layer having a property of reflecting light emitted from the organic light emitting layer 130 so as to be emitted to the outside through the second electrode 120. The reflective property may mean that the reflectivity of the incident light is about 70% or more to about 100% or less, or about 80% or more to about 100% or less.

[0051] The first electrode 110 according to the present exemplary embodiment may include silver (Ag), aluminum (Al), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti), gold (Au), palladium (Pd) or an alloy thereof, and may be used as a reflective layer while having an anode function, and may be a three-layer structure of silver (Ag) / indium tin oxide (ITO) / silver (Ag) or indium tin oxide (ITO) / silver (Ag) / indium tin oxide (ITO).

[0052] As described later, the second electrode 120 is disposed to overlap the first electrode 110 via the organic light emitting layer 130 interposed therebetween. The second electrode 120 according to the present exemplary embodiment may function as a cathode. However, it is not limited thereto, and when the first electrode 110 functions as a cathode, the second electrode 120 may be an anode.

[0053] The second electrode 120 according to the present exemplary embodiment may be a transflective electrode for emitting light emitted from the organic light emitting layer 130 to the outside. Here, the transflective electrode means an electrode having a transflective property of transmitting a portion of incident light to the second electrode 120 and reflecting the remaining portion of light to the first electrode 110. Here, the transflective property may mean a reflectivity of about 0.1% or more and about 70% or less, or about 30% or more and about 50% or less with respect to incident light.

[0054] The second electrode 120 according to the present exemplary embodiment may include an oxide having transflective properties and conductivity such as ITO or IZO, or silver (Ag), magnesium (Mg), aluminum (Al), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti), gold (Au), palladium (Pd), or an alloy.

[0055] In this case, the second electrode 120 of the present exemplary embodiment can smoothly emit the light emitted from the organic light emitting layer 130 to the outside, and in particular, in order to smoothly emit blue light, it can have a transmittance of about 20% or more for light with a wavelength of 430nm to 500nm. This is the minimum transmittance of the color achieved by the organic light emitting diode according to the present exemplary embodiment, and it is preferred to be closer to 100%.

[0056] In the organic light emitting layer 130, holes and electrons transferred from the first electrode 110 and the second electrode 120 meet each other, thereby forming excitons to emit light. Figure 1 In the embodiment, the organic light-emitting layer 130 includes a blue light-emitting layer 130B, and may also include a red light-emitting layer 130R and a green light-emitting layer 130G, or may have a single-layer structure in which the blue light-emitting layer 130B, the red light-emitting layer 130R and the green light-emitting layer 130G are respectively arranged in the same layer on the first electrode 110.

[0057] Blue, red and green are three primary colors for realizing colors, and their combination can realize various colors. The blue light emitting layer 130B, the red light emitting layer 130R and the green light emitting layer 130G form blue pixels, red pixels and green pixels respectively. The blue light emitting layer 130B, the red light emitting layer 130R and the green light emitting layer 130G can be disposed on the upper surface of the first electrode 110.

[0058] A hole transport layer 160 may be further included between the first electrode 110 and the organic light emitting layer 130. The hole transport layer 160 may include at least one of a hole injection layer and a hole transport layer. The hole injection layer facilitates the injection of holes from the first electrode 110, and the hole transport layer transports holes from the hole injection layer. The hole transport layer 160 may be formed of a double layer in which the hole transport layer is formed on the hole injection layer, and may be formed of a single layer in which a material forming the hole injection layer and a material forming the hole transport layer are mixed.

[0059] An electron transfer layer 170 may be further included between the second electrode 120 and the organic light emitting layer 130. The electron transfer layer 170 may include at least one of an electron injection layer and an electron transport layer. The electron injection layer facilitates the injection of electrons from the second electrode 120, and the electron transport layer transports electrons transferred from the electron injection layer. The electron transfer layer 170 may be formed of a double layer in which the electron transport layer is formed on the electron injection layer, and may be formed of a single layer in which a material forming the electron injection layer and a material forming the electron transport layer are mixed.

[0060] However, the inventive concept is not limited thereto, and an organic light emitting diode according to an exemplary variation may include an organic light emitting layer 130 having a multi-layer structure. The organic light emitting layer 130 will be referred to as Figure 2 Further description.

[0061] Figure 2 An organic light emitting diode including an organic light emitting layer 130 having a multi-layer structure according to another exemplary embodiment of the described technology is schematically illustrated.

[0062] exist Figure 2 In the exemplary embodiment shown, the configuration other than the organic light emitting layer 130 is the same as that according to the reference Figure 1 The configuration of the organic light emitting diode of the described exemplary embodiment is similar. Therefore, the first electrode 110 and the second electrode 120 are arranged to overlap, the organic light emitting layer 130 is between the first electrode 110 and the second electrode 120 , and the capping layer 140 is on the second electrode 120 .

[0063] In this case, the organic light emitting layer 130 according to the present exemplary embodiment is formed by depositing a plurality of layers 130a, 130b, and 130c. The layers 130a, 130b, and 130c of the organic light emitting layer 130 respectively represent different colors, thereby emitting white light by combining.

[0064] like Figure 2 As shown, the organic light emitting layer 130 according to the present exemplary embodiment may have a three-layer structure in which three layers 130a, 130b, and 130c are deposited; however, the inventive concept is not limited thereto, and the organic light emitting layer 130 may have a structure consisting of two layers.

[0065] As an example, the three-layered organic light emitting layer 130 may include a blue light emitting layer 130a, a yellow light emitting layer 130b, and a blue light emitting layer 130c. However, this is not a limitation of the disclosed concept, and any light emitting layer capable of emitting white light by color combination may be included within the scope of the exemplary embodiments of the described technology.

[0066] Also, although not shown in the drawings, in the case of a two-layered structure of an organic light emitting layer, the two-layered structure may include a blue light emitting layer and a yellow light emitting layer.

[0067] In addition, although not shown in the figure, the charge generation layer may be Figure 2 Between adjacent layers among the multiple layers 130a, 130b and 130c.

[0068] In the display device using the organic light emitting diode according to the present exemplary embodiment, in order to convert the emitted white light into other colors, a color filter layer disposed on the second electrode 120 may be further included.

[0069] For example, the color filter layer may convert white light passing through the second electrode 120 into blue, red, or green, and to this end, may include a plurality of sub-color filter layers respectively corresponding to a plurality of sub-pixels of the organic light emitting diode. The color filter layer converts the color of light emitted from the second electrode 120, so that if the color filter layer is disposed only on the second electrode 120, various position designs may be possible.

[0070] In order to protect the display device from external moisture or oxygen, the color filter layer may be disposed on or under the encapsulation layer, and various arrangement structures of the color filter layer are possible, so that the implementation scope of the present exemplary embodiment can be applied to these arrangement structures.

[0071] In addition to emitting white light by including the organic light emitting layer 130 composed of a plurality of layers 130a, 130b, and 130c stacked on each other, Figure 2 The organic light emitting diode according to the exemplary embodiment is shown Figure 1 Therefore, the following reference is made to Figure 1 The following description of the organic light emitting diode can also be applied to Figure 2 An exemplary embodiment is shown.

[0072] The blue light emitting material included in the blue light emitting layer 130B according to the present exemplary embodiment has a peak wavelength ranging from about 430 nm to 500 nm in a photoluminescence (PL) spectrum.

[0073] like Figure 1 As shown, an auxiliary layer BIL for improving the efficiency of the blue light emitting layer 130B may be below the blue light emitting layer 130B. The auxiliary layer BIL may have a function of improving the efficiency of the blue light emitting layer 130B by controlling hole charge balance.

[0074] Likewise, if Figure 1 As shown, the red resonance auxiliary layer 130R' and the green resonance auxiliary layer 130G' may be respectively under the red light emitting layer 130R and the green light emitting layer 130G. The red resonance auxiliary layer 130R' and the green resonance auxiliary layer 130G' are added to match the resonance distance of each color. Alternatively, a separate resonance auxiliary layer may not be formed under the blue light emitting layer 130B and the auxiliary layer BIL.

[0075] The pixel defining layer 150 may be on the first electrode 110. Figure 1 As shown, the pixel defining layers 150 are respectively between the blue light emitting layer 130B, the red light emitting layer 130R, and the green light emitting layer 130G, thereby dividing the light emitting layer for each color.

[0076] The capping layer 140 is formed on the second electrode 120 to control the length of the optical path of the element, thereby adjusting the optical interference distance. Figure 1 As shown, unlike the auxiliary layer BIL, the red resonance auxiliary layer 130R′, and the green resonance auxiliary layer 130G′, the capping layer 140 according to the present exemplary embodiment may be commonly included in each of the blue pixel, the red pixel, and the green pixel.

[0077] The organic light emitting layer 130 according to the present exemplary embodiment (particularly, the reaction to exposure to light such as sunlight) is damaged by wavelengths around 405 nm, so that the performance of the organic light emitting diode may be deteriorated. Therefore, 405 nm is a wavelength of light that causes the organic light emitting diode to deteriorate, and will be referred to as a "harmful wavelength" herein.

[0078] The capping layer 140 according to the present exemplary embodiment is formed by including a material that blocks light around 405 nm, which is a harmful wavelength region, of light incident on the organic light emitting layer 130 to prevent degradation of the organic light emitting layer 130 included in the organic light emitting diode.

[0079] The capping layer 140 according to the present exemplary embodiment may include a material satisfying Formula 1 below.

[0080] k 1 -k 2 >0.10[Formula 1]

[0081] In formula 1, k 1 is the absorptivity of light with a wavelength of 405 nm, and k 2 is the absorbance of light having a wavelength of 430 nm.

[0082] In order to block light in the 405 nm region which is a harmful wavelength region, the cover layer 140 according to the present exemplary embodiment may have a k value of 0.25 or more. 1 As the absorbance at 405nm. 1 When it is less than 0.25, the capping layer 140 according to the present exemplary embodiment cannot effectively block light of 405 nm wavelength in the harmful wavelength region, making it difficult to obtain the effect of preventing the organic light emitting layer 130 from being degraded.

[0083] According to the present exemplary embodiment, after the capping layer 140 according to the present exemplary embodiment is formed by depositing an organic material on a silicon substrate as a thin film having a thickness of 70 nm, the absorption rate k is measured using a FILMETRICS F10-RT-UV device. 1 and k 2 And the value of the refractive index described below.

[0084] With k 1 As k increases, more light at 405 nm in the harmful wavelength region is blocked. As an example of the present exemplary embodiment, the material forming the cover layer 140 may be selected so that k 1 is 0.8 or less, and preferably, the material forming the cover layer 140 may be selected so that k 1 However, this is only an example, and the selection range of the material forming the cover layer 140 may be determined by considering various factors such as the thickness of the cover layer 140 and the use environment.

[0085] On the other hand, the organic light emitting layer 130 according to the present exemplary embodiment has a high transmittance for light of a wavelength of 430 nm, which is blue light, while blocking light of a wavelength of 405 nm, which is in a harmful wavelength region. Thus, the harmful wavelength is blocked without impairing the efficiency of the blue series light. For this reason, the cover layer 140 according to the present exemplary embodiment may have an absorptivity k of less than 0.25 for light of a wavelength of 430 nm, which is a wavelength of the blue series light. 2 .

[0086] When k 2 When it is greater than 0.25, the ratio of blue light absorbed by the capping layer 140 increases, so that it may be difficult to realize various colors through the organic light emitting diode according to the present exemplary embodiment.

[0087] When k 2 When it is closer to 0, the ratio of blue light absorbed by the cover layer 140 decreases, so that the efficiency of blue light can be increased.

[0088] In this case, the cover layer 140 according to the present exemplary embodiment may include a material having a high refractive index for blue series light. In this way, the luminous efficiency in the blue region is not weakened. Specifically, the cover layer 140 according to the present exemplary embodiment may have a refractive index of 2.0 or more in the wavelength range of 430nm to 470nm. If the refractive index of the cover layer 140 is increased, a resonance effect may be further generated by refraction, so that the luminous efficiency may be improved.

[0089] In order to smoothly generate the resonance effect, the capping layer 140 according to the present exemplary embodiment may have a thickness of 200 nm or less (excluding 0). As an example, the capping layer 140 may be formed to have a thickness of 60 nm to 80 nm, but the inventive concept is not limited thereto.

[0090] In the above formula 1, it is preferred that k 1 and k 2 Therefore, in formula 1, k 1 and k 2 The difference between them may be greater than 0.1, which is the absorption rate k for light of 405 nm wavelength which is a harmful wavelength region. 1 The absorption rate k for the light with a wavelength of 430 nm, which is the wavelength region of blue light, is 2 The lower limit of the difference between .

[0091] In k 1 and k 2When the difference between the two is less than 0.1, the light in the harmful wavelength region can still be blocked, but the luminous efficiency of the blue light may be reduced. Alternatively, the luminous efficiency of the blue light can be maintained, but the light in the harmful wavelength region may not be effectively blocked, so that it is impossible to prevent the degradation of the organic light emitting layer 130.

[0092] Therefore, in order to obtain a desired level of luminous efficiency of blue light while effectively blocking light in the harmful wavelength region, it is preferred that the absorption rate k for light of 405 nm wavelength in the harmful wavelength region is 1 The absorption rate k for the blue light wavelength region of 430 nm 2 The difference between them is greater than 0.1. 1 -k 2 As the absorption rate of light in the blue region increases, the absorption rate of light in the blue region decreases, and at the same time a large percentage of light in the harmful wavelength region is absorbed, so that the overall efficiency can be improved. It is further preferred that the absorption rate k for light of 405 nm wavelength in the harmful wavelength region is 1 The absorption rate k for the blue light wavelength region of 430 nm 2 The difference between them is greater than 0.3, and more preferably, the absorption rate k for light of 405 nm wavelength in the harmful wavelength region is 1 The absorption rate k for the blue light wavelength region of 430 nm 2 The difference between them is greater than 0.5. 1 and k 2 The larger the difference is, the higher the transmittance in the blue region can be, while more light in the harmful wavelength region is absorbed.

[0093] Therefore, it can be confirmed that the absorption rate k for the light of 405nm wavelength in the harmful wavelength region is 1 The absorption rate k for the blue light wavelength region of 430 nm 2 The difference greater than 0.1 is a threshold value of the minimum value capable of maintaining the transmission efficiency of light in the blue region while absorbing light in the harmful wavelength region.

[0094] The cover layer 140 according to the present exemplary embodiment, which is an organic material including carbon atoms and hydrogen atoms, may include at least one selected from the group including aromatic hydrocarbon compounds, aromatic heterocyclic compounds, and amine compounds, wherein the aromatic hydrocarbon compounds, aromatic heterocyclic compounds, and amine compounds include a substituent having at least one selected from the group including oxygen atoms, sulfur atoms, nitrogen atoms, fluorine atoms, silicon atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0095] Specific examples of the compound that may be used as the capping layer 140 according to the present exemplary embodiment may be materials according to Chemical Formula 1 to Chemical Formula 7 below.

[0096] Chemical formula 1

[0097]

[0098] N 4 , N 4’ -bis(4-9H-carbazol-9-yl)phenyl)-N 4 , N 4’ -Diphenyl-[1,1'-biphenyl]-4,4'-diamine

[0099] Chemical formula 2

[0100]

[0101] N 4 , N 4’ -bis[1,1'-biphenyl]-4-yl)-N 4 , N 4’ -Bis(dibenzo[b,d]furan-2-yl)-[1,1'-biphenyl]-4,4'-diamine

[0102] Chemical formula 3

[0103]

[0104] N 4 , N 4’ -[1,1'-biphenyl]-4,4'-diyl)bis(N 4 , N 4 , N 4’ -triphenyl-[1,1'-biphenyl]-4,4'-diamine)

[0105] Chemical formula 4

[0106]

[0107] N 4 , N 4’ -bis[1,1'-biphenyl]-4-yl)-N 4 , N 4’ -Bis(4'-methyl-[1,1'-biphenyl]-4-yl)-[1,1'-biphenyl]-4,4'-diamine

[0108] Chemical formula 5

[0109]

[0110] N 4 , N 4’ -bis[1,1'-biphenyl]-4-yl)-N 4 , N 4’-Diphenyl-[1,1':4',1"-triphenyl]-4,4"-diamine

[0111] Chemical formula 6

[0112]

[0113] N,N'-((9H-fluorene-9,9-diyl)bis(3,1-phenylene))bis(N-([1,1'-biphenyl]-4-yl)-[1,1'-biphenyl]-4-amine)

[0114] Chemical formula 7

[0115]

[0116] N 4 , N 4’ -bis(dibenzo[b,d]thiophen-2-yl)-N 4 , N 4’ -Bis(4'-methyl-[1,1'-biphenyl]-4-yl)-[1,1'-biphenyl]-4,4'-diamine

[0117] Hereinafter, in order to confirm the effect of the organic light emitting diode according to the present exemplary embodiment, among Chemical Formulas 1 to 7, Chemical Formulas 1 to 6 are selected as Exemplary Embodiments 1 to 6, and materials such as Chemical Formulas 8 and 9 are selected as Comparative Examples 1 and 2 to measure the absorption rate, refractive index and blocking rate, and confirm the blocking effect.

[0118] Chemical formula 8

[0119]

[0120] N 4 , N 4’ -Diphenyl-N 4 , N 4’ -Bis(9-phenyl-9H-carbazol-3-yl)-[1,1'-biphenyl]-4,4'-diamine

[0121] Chemical formula 9

[0122]

[0123] N 4 , N 4’ -di(naphthalen-1-yl)-N 4 , N 4’ -Diphenyl-[1,1'-biphenyl]-4,4'-diamine

[0124] Figure 3is a graph showing the absorptivity, refractive index, transmittance and optical spectrum of the cover material corresponding to Exemplary Embodiment 1, and Figure 4 To show the graphs of the absorbance, refractive index, transmittance, and sunlight spectrum of the cover material corresponding to Comparative Example 1, the absorbance, refractive index, and blocking rate of each material corresponding to Exemplary Embodiment 1 to Exemplary Embodiment 6 and Comparative Examples 1 and 2 were measured at the same time, and the calculation results are summarized in Table 1. "Blocking rate" means "(incident light-transmitted light) / incident light×100%".

[0125] (Table 1)

[0126]

[0127]

[0128] As described in Table 1, the materials for the cover layer 140 according to Comparative Examples 1 and 2 have an absorptivity k of less than 0.25 at a wavelength of 405 nm. 1 . k 2 Comparative Example 1, in which k is 0, satisfies the conditions of the present exemplary embodiment. However, in Comparative Example 1, the refractive index n at a wavelength of 450 nm is less than 2, and according to Formula 1, k 1 and k 2 The difference between is less than 0.1. In Comparative Example 1, except for k 2 Except for the above, the conditions of the cover layer 140 according to the present exemplary embodiment are not all satisfied. 2 is 0, and according to formula 1, k 1 and k 2 The difference between them is greater than 0.1, however the material has an absorptivity k of 0.248 1 , which is less than 0.25.

[0129] In this case, based on the blocking rate of Comparative Example 1 to block light of 405 nm wavelength in a harmful wavelength region, the blocking rates of Exemplary Embodiments 1 to 6 and Comparative Example 2 are relatively calculated and described as a blocking effect.

[0130] Even if all other conditions are met as in Comparative Example 2 and only k 1 It can also be confirmed that the blocking effect of blocking the 405 nm wavelength in the harmful wavelength region is improved by 20% or more compared with Comparative Example 1.

[0131] However, as shown in Table 1, in the case of Exemplary Embodiment 1 to Exemplary Embodiment 6, it can be confirmed that the effect of blocking light of 405 nm wavelength in the harmful wavelength region is exerted at a ratio of at least more than 50% compared with Comparative Example 1.

[0132] Moreover, when comparing Comparative Example 1 with Exemplary Embodiments 1 to 6, referring to Exemplary Embodiment 3 in which the blocking effect was measured to be the lowest, which was improved by 57% compared with Comparative Example 1, it can be confirmed that the blocking effect of Exemplary Embodiment 3 is improved by more than half relative to Comparative Example 1.

[0133] Next, when the organic light emitting diodes including the cover layer 140 according to Exemplary Embodiments 1 to 6 and Comparative Examples 1 and 2 were exposed to a light source having a wavelength of 405 nm including a harmful wavelength region for a predetermined time, a comparison result of the degree of degradation of the organic light emitting layer 130 included in the organic light emitting diodes is described in Table 2. The light source used according to the present exemplary embodiment is an artificial sunlight light source that emits artificial light similar to the spectrum of sunlight.

[0134] (Table 2)

[0135]

[0136]

[0137] Each sample was manufactured to have a color temperature of 7200K as measured in the 0 cycle exposure time. Next, if each sample was exposed to a light source having a wavelength of 405nm including a harmful wavelength region for a predetermined time, the organic light emitting layer 130 included in each sample was damaged by the harmful wavelength, so that the color temperature changed. Therefore, it can be considered that when the amount of color temperature change is large, the degradation of the organic light emitting layer 130 is generated in large quantities.

[0138] As shown in Table 2, in the case of Comparative Examples 1 and 2, the temperature change is greater than 400 K. When the amount of color temperature change is 400 K or more, the white change can be detected by the user or by the naked eye, so that the sample is considered to be a defective board. In contrast, in the case of Exemplary Embodiments 1 to 6, the change in color temperature is small, ranging from 10 K to 80 K, which is very different from 400 K, which is an amount of color temperature change that can be detected by the naked eye.

[0139] Therefore, light of 405 nm wavelength, which is a harmful wavelength region, is blocked by the capping layer 140 included in Exemplary Embodiments 1 to 6, compared to Comparative Examples 1 and 2. The presence of the capping layer 140 reduces degradation of the organic light emitting layer 130 .

[0140] Hereinbefore, the organic light emitting diode according to the present exemplary embodiment has been described. According to the described technology, degradation of the organic light emitting layer 130 can be prevented by blocking light of a harmful wavelength region, and an organic light emitting diode in which blue light emitting efficiency is not deteriorated can be provided.

[0141] While the invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but on the contrary is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A light emitting diode, comprising: a first electrode; a second electrode overlapping the first electrode; a light emitting layer between the first electrode and the second electrode; as well as a covering layer on the second electrode, wherein the cover layer has an absorptivity of 0.25 or more for light of 405 nm wavelength, The covering layer includes a compound represented by chemical formula A: [Chemical formula A] A1 is R1 to R4 are each independently selected from 2. The light emitting diode according to claim 1, wherein The cover layer has an absorptivity of less than 0.25 at a wavelength of 430 nm.

3. The light emitting diode according to claim 1, wherein The covering layer satisfies: k1-k2>0.10 Wherein k1 is the absorbance at a wavelength of 405 nm, and k2 is the absorbance at a wavelength of 430 nm.

4. The light emitting diode according to claim 1, wherein The cover layer has a refractive index of 2.0 or more at a wavelength range of 430 nm to 470 nm.

5. The light emitting diode according to claim 1, wherein The light-emitting layer includes a blue light-emitting layer, and The blue light emitting material included in the blue light emitting layer has a light emitting spectrum peak wavelength of 430 nm to 500 nm.

6. The light emitting diode according to claim 1, wherein The second electrode has a light transmittance of 20% or more at a wavelength range of 430 nm to 500 nm.

7. The light emitting diode according to claim 1, wherein The cover layer blocks 50% or more of light having a wavelength of 405 nm.

8. The light emitting diode according to claim 1, wherein The light emitting layer is combined with multiple layers representing different colors.

9. The light emitting diode according to claim 8, wherein The plurality of layers includes a structure in which 2 layers or 3 layers are deposited.

10. The light emitting diode according to claim 1, wherein The cover layer has an absorptivity of 1.0 or less at a wavelength of 405 nm.

11. The light emitting diode according to claim 1, wherein The capping layer has a thickness of 200 nm or less.

12. The light emitting diode according to claim 1, wherein the compound represented by Chemical Formula A comprises one or more selected from the group consisting of compounds represented by Chemical Formula 1 to Chemical Formula 7: [Chemical formula 1] [Chemical formula 2] [Chemical formula 3] [Chemical formula 4] [Chemical formula 5] [Chemical formula 6] [Chemical formula 7]

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