KR100696497B1 - An organic electroluminescent device and a flat display device comprising the same - Google Patents

Abstract

The present invention is a pixel electrode; Counter electrode; And an organic layer including a hole injection layer, a hole transporting layer, and a light emitting layer between the pixel electrode and the counter electrode, wherein the sum of the thickness of the hole injection layer and the thickness of the hole transporting layer is different for each color of light emission, and is red and green. The present invention relates to an organic electroluminescent device in which the sum of the thicknesses of the hole injection layer and the hole transport layer is reduced according to the order of blue light emission colors, and a flat panel display device having the organic electroluminescent device. The organic electroluminescent device has excellent efficiency and color coordinates.

Description

An organic electroluminescent device and a flat display device comprising the same

1 is a view schematically showing the structure of an embodiment of an organic electroluminescent device according to the present invention,

2 is a view schematically showing an organic electroluminescent device having all of the red, green, and blue light emitting layers according to the present invention;

3 to 6 are schematic views of a flat panel display device capable of displaying a screen on both sides of a flat panel display device having an embodiment of an organic light emitting device according to the present invention;

7 and 8 show the efficiency and color coordinates of the red light emitting device of one embodiment of the organic electroluminescent device according to the present invention,

9 and 10 show the efficiency and color coordinates of the green light emitting device of one embodiment of the organic electroluminescent device according to the present invention,

11 illustrates power consumption of a blue light emitting device in one embodiment of the organic electroluminescent device according to the present invention.

<Description of Signs for Main Parts of Drawings>

210, 310a, 310b: pixel electrode 216: hole injection layer

218: hole transport layer 220, 225, 230: light emitting layer

240: electron transport layer 250: electron injection layer

260, 350a, 350b: counter electrode 330a, 330b: organic layer

The present invention relates to an organic light emitting display device and a flat panel display, and more particularly, to an organic light emitting display device having an improved efficiency and color coordinates and a flat display device having the same.

An organic electroluminescent device is a self-luminous device that utilizes a phenomenon in which light is generated while electrons and holes are combined in an organic layer when a current flows through a fluorescent or phosphorescent organic film. It has a structure. In addition, high-definition can be realized, wide viewing angle can be secured, and video can be fully realized. In addition, high color purity, low power consumption, and low voltage driving are possible, and thus have electrical characteristics suitable for portable electronic devices.

The organic EL device generally uses a multilayer structure such as an electron injection layer, a light emitting layer, a hole transporting layer, etc., instead of using only a single light emitting layer as an organic layer for improving efficiency and lowering a driving voltage. For example, Japanese Patent Laid-Open No. 2002-252089 discloses an organic electroluminescent device having a socket hole transport layer.

However, the conventional organic electroluminescent device cannot achieve satisfactory levels of efficiency, color coordinates, and lifespan. Therefore, an improvement thereof is urgent.

In order to solve the problems of the prior art as described above, the present invention by optimizing the total of the hole injection layer thickness and the hole transport layer thickness for each emission color, the organic electroluminescent device having improved efficiency and color coordinates for each emission color and An object of the present invention is to provide a flat panel display device including the organic electroluminescent element.

In order to achieve the above object of the present invention, the first aspect of the present invention,

Pixel electrodes; Counter electrode; And an organic layer including a hole injection layer, a hole transporting layer, and a light emitting layer between the pixel electrode and the counter electrode, wherein the sum of the thickness of the hole injection layer and the thickness of the hole transporting layer is different for each color of light emission, and is red and green. The present invention provides an organic electroluminescent device in which the sum of the thicknesses of the hole injection layer and the hole transport layer decreases according to the order of blue light emission colors.

In order to achieve the another object of the present invention, a second aspect of the present invention includes the organic electroluminescent element as described above, wherein the pixel electrode of the organic electroluminescent element is electrically connected to the source electrode or the drain electrode of the thin film transistor. Provided is a connected flat panel display.

In order to achieve another object of the present invention, the third aspect of the present invention,

A transparent substrate having a first display portion and a second display portion;

At least one first organic electroluminescent device which is located in the first display unit and emits light in at least a first direction perpendicular to the substrate and has a first pixel electrode, a first counter electrode and a first organic layer interposed therebetween device; And

At least one second organic electric field positioned in the second display unit and emitting light in a second direction opposite to the first direction and having a second pixel electrode, a second counter electrode, and a second organic layer interposed therebetween Including a light emitting element,

Provided is a flat panel display device in which at least one of the first organic electroluminescent element and the second organic electroluminescent element is an organic electroluminescent element as described above.

The organic electroluminescent device according to the present invention is improved efficiency and color coordinates, it can be obtained a flat panel display device having improved reliability.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

The organic electroluminescent device according to the present invention includes a pixel electrode and a counter electrode, and includes a hole injection layer, a hole transport layer, and a light emitting layer between the pixel electrode and the counter electrode, wherein the thickness of the hole injection layer and the hole transport layer The sum of the thicknesses is different for each of the emission colors, and the sum of the thickness of the hole injection layer and the thickness of the hole transport layer decreases according to the order of the emission colors of red, green, and blue. This is in consideration of the fact that the resonance effects are different for each of the emission colors. Thus, by controlling the thicknesses of the hole injection layer and the hole transport layer for each emission color, efficiency and color purity may be improved for each emission color.

In one embodiment of the organic electroluminescent device according to the present invention, when the light emitting color is red, the sum of the thickness of the hole injection layer and the thickness of the hole transport layer is 2000 kPa to 2400 kPa, more preferably 2100 kPa to 2300 kPa Can be. In particular, when the emission color is red, the sum of the thickness of the hole injection layer and the thickness of the hole transport layer may be 2200 kPa. When the sum of the thickness of the hole injection layer and the thickness of the hole transport layer is more than 2400 kHz or less than 2000 kHz, the hole injection characteristics and hole transfer characteristics suitable for the resonance effect of the red light emitting layer may not be obtained, so that the color purity may be lowered and the efficiency may be reduced. have. In addition, when the voltage exceeds 2400 kV, the driving voltage may increase.

The thickness of each of the hole injection layer and the hole transport layer may be variously selected within the above range. For example, the hole injection layer may have a thickness of 800 kPa to 1200 kPa. The thickness of each of the hole injection layer and the hole transport layer may be adjusted according to the material of each layer or the material of the pixel electrode, and the like, and may be variously selected within the total range of the thickness of the hole injection layer and the thickness of the hole transport layer as described above. Can be. As an example, when the thickness of the hole injection layer is 1000 kPa, the thickness of the hole transport layer may be 1000 kPa to 1400 kPa, preferably 1100 kPa to 1300 kPa, more preferably 1200 kPa, but the present invention is not limited thereto.

In one embodiment of the organic electroluminescent device according to the present invention, when the emission color is green, the sum of the thickness of the hole injection layer and the thickness of the hole transport layer may be 1600 kPa to 2000 kPa, more preferably 1700 kPa to 1900 kPa. have. In particular, when the light emitting color is green, the sum of the thickness of the hole injection layer and the thickness of the hole transport layer may be 1800 μs. When the sum of the thickness of the hole injection layer and the thickness of the hole transporting layer is more than 2000 kHz or less than 1600 kHz, color purity may be deteriorated due to poor hole injection and hole transport characteristics suitable for the resonance effect of the green light emitting layer. can do. In addition, when the voltage exceeds 2000 kV, the driving voltage may increase. The thickness of each of the hole injection layer and the hole transport layer may be variously selected within the above range. For example, the hole injection layer may have a thickness of 800 kPa to 1200 kPa. The thickness of each of the hole injection layer and the hole transport layer may be adjusted according to the material of each layer or the material of the pixel electrode, and the like, and may be variously selected within the total range of the thickness of the hole injection layer and the thickness of the hole transport layer as described above. Can be. As an example, when the thickness of the hole injection layer is 1000 kPa, the thickness of the hole transport layer may be 600 kPa to 1000 kPa, preferably 700 kPa to 900 kPa, more preferably 800 kPa, but is not limited thereto.

In one embodiment of the organic electroluminescent device according to the present invention, when the light emitting color is blue, the sum of the thickness of the hole injection layer and the thickness of the hole transport layer may be 1200 kPa to 1600 kPa, more preferably 1300 kPa to 1500 kPa. have. In particular, when the emission color is blue, the sum of the thickness of the hole injection layer and the thickness of the hole transport layer may be 1400 kPa. When the sum of the thickness of the hole injection layer and the thickness of the hole transporting layer is more than 1600 GPa or less than 1200 GPa, color purity may be deteriorated because it may not have hole injection performance and hole transfer characteristics suitable for the resonance effect of the blue light emitting layer, May decrease. In addition, when the sum of the thickness of the hole injection layer and the thickness of the hole transport layer exceeds 1600 kV, the driving voltage may increase. The thickness of each of the hole injection layer and the hole transport layer may be variously selected within the above range. For example, the hole injection layer may have a thickness of 800 kPa to 1200 kPa. The thickness of each of the hole injection layer and the hole transport layer may be adjusted according to the material of each layer or the material of the pixel electrode, and the like, and may be variously selected within the total range of the thickness of the hole injection layer and the thickness of the hole transport layer as described above. Can be. As an example, when the thickness of the hole injection layer is 1000 kPa, the thickness of the hole transport layer may be 200 kPa to 600 kPa, preferably 300 kPa to 500 kPa, more preferably 400 kPa, but is not limited thereto.

The material constituting the hole injection layer provided in the organic electroluminescent device according to the present invention is not particularly limited. Specific examples include copper phthalocyanine (CuPc) or starburst amines TCTA, m-MTDATA, IDE406 (from Idemitsu Corp.), Pani / DBSA (Polyaniline / Dodecylbenzenesulfonic acid: polyaniline / dodecylbenzenesulfonic acid) or PEDOT / PSS (Poly (3,4-ethylenedioxythiophene) / Poly (4-styrenesulfonate): poly (3,4-ethylenedioxythiophene) / poly (4-styrenesulfonate)) and the like, but are not limited thereto. .

                 Pani / DBSA

                 PEDOT / PSS

The material constituting the hole transport layer provided in the organic electroluminescent device according to the present invention is not particularly limited. Specific examples include 1,3,5-tricarbazolylbenzene, 4,4'-biscarbazolylbiphenyl, polyvinylcarbazole, m-biscarbazolylphenyl, 4,4'-biscarbazolyl-2,2 '-Dimethylbiphenyl, 4,4', 4 "-tri (N-carbazolyl) triphenylamine, 1,3,5-tri (2-carbazolylphenyl) benzene, 1,3,5-tris (2 -Carbazolyl-5-methoxyphenyl) benzene, bis (4-carbazolylphenyl) silane, N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1-biphenyl] -4,4'diamine (TPD), N, N'-di (naphthalen-1-yl) -N, N'-diphenyl benzidine (α-NPD), N, N'-diphenyl-N, N ' -Bis (1-naphthyl)-(1,1'-biphenyl) -4,4'-diamine (NPB), IDE320 (manufactured by Idemitsu Co., Ltd.), poly (9,9-dioctylfluorene-co- N- (4-butylphenyl) diphenylamine) (poly (9,9-dioctylfluorene-co-N- (4-butylphenyl) diphenylamine) (TFB) or poly (9,9-dioctylfluorene-co-bis -N, N-phenyl-1,4-phenylenediamine (poly (9,9-dioctylfluorene-co-bis- (4-butylphenyl-bis-N, N-phenyl-1,4-phenylenediamin) (PFB), etc.) Include but are not limited to.

Hereinafter, an embodiment of the organic electroluminescent device and a method of manufacturing the same according to the present invention will be described with reference to FIGS. 1 and 2. 1 schematically shows a cross-sectional view of an organic electroluminescent device according to the present invention, and FIG. 2 shows an organic electroluminescent device according to the present invention so as to be simultaneously viewed for each emission color.

First, the pixel electrode 210 is formed on the substrate 200. Here, the substrate 200 may be a substrate used in a conventional organic electroluminescent device. In consideration of transparency, surface smoothness, ease of handling, and waterproofness, an organic substrate or a plastic substrate may be variously used. The pixel electrode 210 is a metal having excellent conductivity, such as lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg). -In), magnesium-silver (Mg-Ag), calcium (Ca) -aluminum (Al), aluminum (Al) -ITO and the like can be provided as a reflective electrode, various modifications are possible.

Thereafter, the pixel defining layer 214 defining the organic layer formation region is formed at a predetermined position. The pixel defining layer may be formed using various methods such as a deposition method or a coating method using inorganic or insulating organic materials such as silicon oxide and nitride.

The hole injection layer 216 and the hole transport layer 218 are sequentially formed by vacuum thermal deposition or spin coating on the pixel electrode 210 along the region defined by the pixel defining layer 214. According to FIG. 2, it can be seen that the sum of the thicknesses of the hole injection layer 216 and the hole transport layer 218 sequentially decreases according to the red light emitting area R, the green light emitting area G, and the blue light emitting area B. FIG. Can be. In this case, the thickness of the hole injection layer 216 of each of the R, G, and B light emitting regions may be the same or different. The sum of the thickness of the hole injection layer 216 and the thickness of the hole transport layer 218 and the detailed description of the material forming each layer are the same as described above, and thus will be omitted.

There are various methods of differently forming the sum of the thickness of the hole injection layer and the thickness of the hole transport layer for each of the R, G, and B regions. For example, the hole injection layer and the hole transport layer having the thickness as described above may be formed separately for each of the R, G, and B regions. In another example, the hole injection layer or the hole transport layer is deposited on the entire surface of the hole injection layer and the hole transport layer in the thinnest B region, and then the hole injection layer and the hole transport layer are obtained in order to obtain the required thickness in the R region and the G region. May be further deposited, but is not limited thereto.

Light emitting layers 220, 225, and 230 for each color are formed on the hole injection layer 216 and the hole transport layer 218. The material constituting the light emitting layer of the present invention is not particularly limited.

The red light-emitting layer includes, for example, DCM1, DCM2, Eu (thenoyltrifluoroacetone) 3 (Eu (TTA) 3, butyl-6- (1,1,7,7-tetramethyl zulolidil-9-enyl) -4H-pyran ) {butyl-6- (1,1,7,7, -tetramethyljulolidyl-9-enyl) -4H-pyran: DCJTB} And the like can be used. Alternatively, Alq3 may be formed by doping a dopant such as DCJTB, or by co-depositing Alq3 and rubrene and doping the dopant, 4,4'-N, N'-dicarbazole-biphenyl (4,4'-N Various modifications are possible, such as doping of a dopant such as BTPIr to -N'-dicarbazole-biphenyl) (CBP).

             DCJTB

For example, coumarin 6, C545T, quinacridone, Ir (ppy) _3, etc. may be used as the green light emitting layer. On the other hand, various modifications are possible, such as using Ir (ppy) 3 as a dopant for CBP or coumarin-based material as a dopant for Alq 3 as a host. Specific examples of the coumarin dopant include C314S, C343S, C7, C7S, C6, C6S, C314T, and C545T.

The blue light emitting layer may include, for example, oxadiazole dimer dyes (Bis-DAPOXP), spiro compounds (Spiro-DPVBi, Spiro-6P), triarylamine compounds, and bis ( Styryl) amine (bis (styryl) amine) (DPVBi, DSA), compound (A) Flrpic, CzTT, Anthracene, TPB, PPCP, DST, TPA, OXD-4, BBOT, AZM-Zn, naphthalene moiety BH-013X (Idemitsu Co., Ltd.), which is an aromatic hydrocarbon compound, can be used in various ways. On the other hand, various modifications are possible, for example, IDE105 (trade name, manufactured by Idemitsu Corporation) can be used as the dopant for IDE140 (trade name, manufactured by Idemitsu Corporation).

The thickness of the light emitting layer is 100 kPa to 500 kPa, preferably 100 kPa to 400 kPa. Meanwhile, the thicknesses of the light emitting layers in the R, G, and B regions may be the same or different from each other. If the thickness of the light emitting layer is less than 200 kW, the lifetime is reduced, and if the thickness of the light emitting layer is more than 500 kW, the driving voltage rise is high, which is not preferable.

A hole suppression layer (not shown) may be selectively formed on the light emitting layer by vacuum deposition or spin coating a material for hole suppression. The material for the hole suppression layer used at this time is not particularly limited, but should have ionization potential higher than that of the light emitting compound while having electron transport ability, typically bis (2-methyl-8-quinolato)-(p-phenylphenolato) -aluminum ( Balq), bathocuproine (BCP), tris (N-arylbenzimidazole) (TPBI), and the like.

The thickness of the hole suppression layer is 30 kPa to 60 kPa, preferably 40 kPa to 50 kPa. This is because when the thickness of the hole suppression layer is less than 30 kW, the hole suppression property may not be well implemented, and when the hole suppression layer is more than 60 kW, the driving voltage may increase.

An electron transport layer 240 is selectively formed by vacuum deposition or spin coating an electron transport material on the light emitting layer or the hole suppression layer. The electron transporting material is not particularly limited and may be Alq 3 or the like.

The electron transport layer 240 may have a thickness of 100 kPa to 400 kPa, preferably 250 kPa to 350 kPa. This is because when the thickness of the electron transport layer 240 is less than 100 kV, the charge transport may be broken due to excessive electron transport speed, and when the electron transport layer 240 exceeds 400 kV, the driving voltage may increase.

The electron injection layer 250 may be formed on the emission layer, the hole suppression layer, or the electron transport layer by using a vacuum deposition method or a spin coating method. Materials for forming the electron injection layer 250 may include materials such as BaF ₂ , LiF, NaCl, CsF, Li ₂ O, BaO, Liq, but are not limited thereto.

The electron injection layer 250 may have a thickness of 2 kPa to 10 kPa, preferably 2 kPa to 5 kPa. Among these, 2 GPa-4 GPa are especially suitable thickness. If the thickness of the electron injection layer 250 is less than 2 kW, it may not serve as an effective electron injection layer, and if the thickness of the electron injection layer 250 exceeds 10 kW, the driving voltage may be increased. Because.

Subsequently, the organic electroluminescent device is completed by depositing a material for the counter electrode on the electron injection layer to form the counter electrode 260.

As the material for the counter electrode, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), zinc oxide (ZnO), and the like, which are transparent metal oxides having excellent conductivity, may be used. Alternatively, lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), calcium It is possible to form a transparent electrode by forming (Ca) -aluminum (Al) or the like into a thin film. Of course, the material forming the counter electrode is not limited to the above-described metal and metal combination. The pixel electrode and the counter electrode may serve as an anode and a cathode, respectively, and vice versa.

In the above, an embodiment of the organic electroluminescent device and a method of manufacturing the same have been described with reference to FIGS. 1 and 2, but the organic layer is selected from the group consisting of a hole suppression layer, an electron transport layer, an electron injection layer, and an electron suppression layer. Organic electroluminescent devices of various structures are possible, such as one or more layers may be further provided.

The organic EL device according to the present invention may be provided in various types of flat panel display devices, for example, passive matrix organic light emitting display devices and active matrix organic light emitting display devices. In particular, when provided in an active matrix organic light emitting display device, the pixel electrode may be electrically connected to a source electrode or a drain electrode of the thin film transistor.

In addition, the organic EL device according to the present invention may be provided in a flat panel display that can display a screen on both sides. The flat panel display includes a transparent substrate having a first display unit and a second display unit; At least one first organic electroluminescent element positioned in the first display unit and emitting light in at least a first direction perpendicular to the substrate and having a first pixel electrode, a first counter electrode, and a first organic layer interposed therebetween ; And at least one second organic light positioned in the second display unit and emitting light in a second direction opposite to the first direction and having a second pixel electrode, a second counter electrode, and a second organic layer interposed therebetween. Including an electroluminescent device, at least one of the first organic electroluminescent device and the second organic electroluminescent device may be an organic electroluminescent device according to the present invention as described above.

The first display unit and the second display unit of the flat panel display device may be positioned on the same surface of the transparent substrate or on opposite surfaces of the transparent substrate. Various embodiments of the flat panel display device according to the present invention are shown in FIGS. 3 to 6, respectively.

The flat panel display shown in FIG. 3 includes a first organic electroluminescent element 370a and a second organic electroluminescent element 370b in the same direction with respect to the substrate 300, but includes the first display unit a and the second organic electroluminescent element 370b. The direction in which light is emitted from the display portion b is different. The first organic EL device 370a including the first pixel electrode 310a, the first organic layer 330a, and the second counter electrode 350a is a top emission type emitting light in a direction opposite to the substrate 300. The first pixel electrode 310a is a reflective electrode and the first counter electrode 350a is a transparent electrode. The first organic EL device 370a may be an organic EL device according to the present invention as described above.

Meanwhile, the second organic electroluminescent element 370b provided on the same surface as the first organic electroluminescent element 370a with respect to the substrate 300 may include the second pixel electrode 310b, the second organic layer 330b, and the first organic electroluminescent element 370b. Including a back electrode 350b, a light emitting type for emitting light toward the substrate 300, the second pixel electrode 310b is a transparent electrode, the second counter electrode 350b is provided as a reflective electrode . The second organic electroluminescent device may have various known structures.

The flat panel display illustrated in FIG. 4 includes a first organic electroluminescent element 470a and a second organic electroluminescent element 470b in opposite directions with respect to the substrate 400, and includes the first display unit a and the first organic electroluminescent element 470b. 2 The direction in which light is emitted from the display portion b is different. A first organic electroluminescent element 470a and a first pixel electrode 410b and a second organic layer 430b including a first pixel electrode 410a, a first organic layer 430a, and a first counter electrode 450a; The second organic EL device 470a including the second counter electrode 450b is a top emission type in which light is emitted in a direction opposite to the substrate 400, and includes a first pixel electrode 410a and a second pixel electrode ( 410b is a reflective electrode, and the first counter electrode 450a and the second counter electrode 450b are provided as transparent electrodes. At least one of the first organic electroluminescent device and the second organic electroluminescent device may be an organic electroluminescent device as described above.

The flat panel display illustrated in FIG. 5 includes a first organic electroluminescent element 570a and a second organic electroluminescent element 570b in the same direction with respect to the substrate 500, and is emitted from the first display unit a. Light is in a direction opposite to the substrate, and light emitted from the second display portion b is in both directions with respect to the substrate. The first organic electroluminescent element 570a including the first pixel electrode 510a, the first organic layer 530a, and the second counter electrode 550a has a top emission type, and the first pixel electrode is a reflective electrode, and the first The counter electrode 550a is provided as a transparent electrode. The first organic EL device 570a may be an organic EL device according to the present invention as described above.

On the other hand, the second organic EL device 570b provided on the same surface as the first organic EL device 570a with respect to the substrate 500 may include a second pixel electrode 510b, a second organic layer 530b, and Including a second counter electrode 550b, and as a double-sided light emission type, both the second pixel electrode 510b and the second counter electrode 550b are provided as transparent electrodes. The second organic electroluminescent device may have various known structures.

The flat panel display illustrated in FIG. 6 includes a first organic electroluminescent element 670a and a second organic electroluminescent element 670b in opposite directions with respect to the substrate 600. Light emitted from the first display unit a is opposite to the substrate, and light emitted from the second display unit b is bidirectional with respect to the substrate. The first organic electroluminescent element 670a including the first pixel electrode 610a, the first organic layer 630a, and the second counter electrode 650a has a top emission type, and the first pixel electrode is a reflective electrode, and the first The counter electrode 650a is provided as a transparent electrode. The first organic EL device 670a may be an organic EL device according to the present invention as described above.

On the other hand, the second organic electroluminescent element 670b provided on the surface opposite to the first organic electroluminescent element 670a with respect to the substrate 600 may include a second pixel electrode 610b, a second organic layer 630b, and a first organic electroluminescent element 670b. Including the two opposite electrodes 650b, the two-sided light emission type, both the second pixel electrode 610b and the second opposite electrode 650b are provided as transparent electrodes. The second organic electroluminescent device may have various known structures.

Although the flat panel display according to the present invention has been described with reference to the flat panel display shown in FIGS. 3 and 6 as an example, the present invention is not limited thereto, and various modifications can be made within the range including the organic electroluminescent device according to the present invention as described above. Yes it is possible.

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited only to the following examples.

EXAMPLE

The following production examples illustrate a method of manufacturing organic electroluminescent devices each having a red, green, and blue light emitting layer.

Preparation Example R1

As a reflective pixel electrode, a 1300Å thick (aluminum and ITO) (SDI) substrate is cut into 50 mm x 50 mm x 0.7 mm, ultrasonically cleaned in isopropyl alcohol and pure water for 5 minutes, and then UV for 30 minutes. Ozone was used after washing.

A hole injection layer having a thickness of 1000 Å was formed on the pixel electrode using m-TDATA, which is a hole injection material, and then a hole transport layer having a thickness of 1200 Å was formed by depositing NPB, a hole transporting material, on the hole injection layer.

CBP and BPTIr were formed to have a thickness of 300 Å on the hole transport layer to form a red light emitting layer, and then a Balq was deposited on the light emitting layer to form a hole suppression layer having a thickness of 50 Å. Alq3 was formed to have a thickness of 250 kV on the hole suppression layer to form an electron transport layer, and an electron injection layer was formed by forming LiF on the electron transport layer to have a thickness of 3 mW. Then, MgAg 180 mV was formed as a transparent counter electrode. An electroluminescent device was manufactured. This is called sample R1.

Preparation Example R2

An organic electroluminescent device was formed in the same manner as in Preparation Example R1, except that the hole transport layer in Preparation Example R1 was formed to have a thickness of 1000 GPa. This is called sample R2.

Preparation Example R3

An organic electroluminescent device was formed in the same manner as in Preparation Example R1, except that the hole transport layer was manufactured to a thickness of 1400 μs. This is called sample R3.

Preparation Example R

An organic electroluminescent device was formed in the same manner as in Preparation Example R1, except that the hole transport layer of Preparation Example R1 was formed to have a thickness of 800 GPa. This is called sample R.

Preparation Example G1

A hole transporting material was deposited to form a hole transporting layer of 800 Å in thickness, and the same as in Preparation Example R1 except that a green light emitting layer was formed by forming CBP and Irppy with a thickness of 300 Å as the green light emitting material instead of the red light emitting layer. An organic electroluminescent device was formed by the method. This is called sample G1.

Preparation Example G2

An organic electroluminescent device was formed in the same manner as in Preparation Example G1, except that the hole transport layer in Preparation Example G1 was formed to have a thickness of 600 GPa. This is called sample G2.

Preparation Example G3

An organic electroluminescent device was formed in the same manner as in Preparation Example G1, except that the hole transport layer in Preparation Example G1 was formed to have a thickness of 900 GPa. This is called sample G3.

Preparation Example G

An organic electroluminescent device was formed in the same manner as in Preparation Example G1, except that the hole transport layer in Preparation Example G1 was formed to have a thickness of 500 GPa. This is called sample G.

Preparation Example B1

NPB, which is a hole transporting material, was deposited to have a thickness of 400 kV to form a hole transporting layer, and instead of the red light emitting layer, a blue light emitting layer was formed by forming 150 140 of IDE140 (manufactured by Idemistu) and IDE105 (manufactured by Idemistu) as a blue light emitting material. Except for forming an organic EL device in the same manner as in Preparation Example R1. This is called sample B1.

Preparation Example B2

An organic electroluminescent device was formed in the same manner as in Preparation Example B1, except that the hole transport layer of Preparation Example B1 was formed to have a thickness of 300 GPa. This is called sample B2.

Preparation Example B3

An organic electroluminescent device was formed in the same manner as in Preparation Example B1, except that the hole transport layer in Preparation Example B1 was formed to have a thickness of 500 GPa. This is called sample B3.

Preparation Example B

An organic electroluminescent device was formed in the same manner as in Preparation Example B1, except that the hole transport layer in Preparation Example B1 was formed to have a thickness of 200 GPa. This is called sample B.

Evaluation Example 1 Evaluation of Efficiency, Color Coordinates, and Power Consumption of Samples Obtained from the Production Examples

Performance evaluation was performed on the samples. To this end, the efficiency and color coordinates of the samples R1, R2, R3 and R and the samples G1, G2, G3 and G were evaluated and shown in FIGS. 7 to 10. Efficiency and color purity were evaluated using an IVL measuring device (PhotoResearch PR650, Keithley 238).

On the other hand, the performance of the samples B1, B2, B3 and B was evaluated by measuring the power consumption of each sample, the results are shown in FIG. In the case of blue light emission, the change in color coordinates has a sensitive effect on the overall power consumption. Therefore, performance was evaluated based on power consumption considering both color coordinates and efficiency. Power consumption was calculated by calculating efficiency and color purity using IVL measuring device (PhotoResearch PR650, Keithley 238).

7 to 11 show the thickness of the hole transport layer of each sample.

7 is a graph showing the efficiency of samples R1, R2, R3 and R. According to FIG. 7, the efficiency of the sample R is less than 1, but the efficiency of the sample R1 is 6 or more, indicating that the sample R1 has a very high efficiency.

8 is a graph showing color coordinates of samples R1, R2, R3, and R. FIG. Considering the red NTSC level (0.67, 0.32), the color coordinate of sample R is (0.635, 0.36), which is far below the red NTSC level, but the color coordinate of sample R1 is (0.672, 0.32), which is very excellent. Can be.

9 is a graph showing the efficiency of samples G1, G2, G3 and G. According to FIG. 9, the efficiency of the sample G is only 5, but the efficiency of the sample G1 is about 25, which is 5 times that of the sample G1. Thus, it can be seen that the sample G1 has a very high efficiency.

10 is a graph showing color coordinates of samples G1, G2, G3, and G. FIG. Considering the green NTSC level (0.21, 0.71), the color coordinate of sample G is (0 14, 0.65), which is far below the green NTSC level, but the color coordinate of sample G1 is (0.21, 0.726), which is very good. Able to know.

11 is a graph showing power consumption of samples B1, B2, B3, and B. FIG. According to FIG. 11, the power consumption of the sample B is very high at 570 mW, but the power consumption of the sample B1 is only about 400 mW, and the sample B1 has excellent power consumption.

Example 1

This embodiment is an organic electroluminescent device in which the thickness of the hole injection layer and the hole transport layer is optimized, and describes an embodiment of a method of manufacturing an organic electroluminescent device having both red, green, and blue light emitting layers.

After preparing a substrate having a thin film transistor array, a pixel electrode having a thickness of 1000 Å made of aluminum was formed in a stripe form. In this case, the pixel electrode is formed to be electrically connected to the source electrode or the drain electrode of the thin film transistor provided under the substrate.

A pixel defining layer is formed on the pixel electrode to define regions in which red, green, and blue light emitting layers are to be provided, and then a hole injection layer having a thickness of 1000 Å is formed in the hole injection material m-TDATA along the pixel defining layer. After the formation, NPB, which is a hole transporting material, was deposited on the hole injection layer to a thickness of 400 mm 3. Subsequently, NPB, which is a hole transporting material, is deposited to have a thickness of 400 kPa in the region where the green light emitting layer is to be formed by using a photo mask, and NPB, which is a hole transporting material, is deposited to be 800 kPa in the region where the red light emitting layer is to be formed. The hole transport layer thickness of the region to be formed was 1200 Å, the hole transport layer thickness of the region where the green light emitting layer was to be formed was 800 Å, and the thickness of the region where the blue light emitting layer was to be formed was 400 Å.

Form CBP and BTPIr 300 Å thick as the red light emitting material, CBP and Irppy as 300 Å thick as the green light emitting material, and IDE140 (manufactured by Idemistu) and IDE105 (manufactured by Idemistu) as the blue light emitting material. ) Was formed to a thickness of 150 kHz to form a red light emitting layer, a green light emitting layer, and a blue light emitting layer, respectively.

Balq was deposited on the emission layer to form a hole suppression layer having a thickness of 50 kHz. An Alq3 was formed to a thickness of 250 kV on the hole suppression layer to form an electron transport layer, and a LiF was formed to a thickness of 3 kPa on the electron transport layer. Prepared.

Evaluation Example 2-Performance Evaluation of Organic Electroluminescent Devices Obtained from Example 1

The voltage, current, brightness, efficiency, and color coordinates of the organic electroluminescent device obtained in Example 1 were evaluated using the same method as described in Evaluation Example 1. The results are shown in Table 1 below:

Voltage (V) Current (mA / cm ² ) Luminance (cd / m ² ) Efficiency (cd / A) x color coordinate y color coordinate Red light emitting layer 8.17 37.19 2000 5.39 0.67 0.32 Green light emitting layer 6.56 16.40 4000 24.45 0.21 0.72 Blue light emitting layer 6.36 42.92 600 1.40 0.14 0.06

According to Table 1, it can be seen that the organic electroluminescent device obtained in Example 1 has excellent luminance, efficiency and color purity for each emission color.

Example 2

The present embodiment describes an embodiment of a method of manufacturing a flat panel display device having two or more organic electroluminescent elements, which can be displayed on both sides.

A transparent substrate having a first display region and a second display region and having a thin film transistor was prepared. In the first display area of the substrate, a first organic electroluminescent element was formed by the same method as described in Example 1. Thereafter, a second organic electroluminescent element having a laminated structure as shown in Table 2 is formed on the same surface as the surface on which the first organic electroluminescent element is formed, and the screen is double-sided having a structure as shown in FIG. 3. The flat display apparatus which can display was manufactured. That is, the first organic electroluminescent element is a top emission type having a reflective pixel electrode and a transparent counter electrode, and the second organic electroluminescent element is formed of a bottom emission type having a transparent pixel electrode and a reflective counter electrode. It was.

Red light emitting area Green luminous area Blue emitting area Pixel electrode ITO (1500Å) ITO (1500Å) ITO (1500Å) Hole transport layer NPB (500 Å) NPB (500 Å) NPB (500 Å) Light emitting layer host CBP (300Å) CBP (300Å) IDE140 (200Å) Light emitting layer dopant BTPIr (10% by weight) Ir (ppy) 3 (5% by weight) IDE105 (5% by weight) Hole suppression layer Balq (50 yen) Balq (50 yen) Balq (50 yen) Electron transport layer Alq3 (200 Å) Alq3 (200 Å) Alq3 (200 Å) Electron injection layer LiF (10Å) LiF (10Å) LiF (10Å) Counter electrode Al (3000Å) Al (3000Å) Al (3000Å)

Evaluation Example 3-Performance Evaluation of the Flat Panel Display Device Obtained from Example 2

The voltage, current, brightness, efficiency, and color coordinates of the first and second organic electroluminescent elements of the flat panel display obtained in Example 2 were evaluated using the same method as described in Evaluation Example 1. The performance evaluation results of the first organic electroluminescent device are as described in Table 1 above, and the performance evaluation results of the second organic electroluminescent device are as described in Table 3 below:

Voltage (V) Current (mA / cm ² ) Luminance (cd / m ² ) Efficiency (cd / A) x color coordinate y color coordinate Red light emitting layer 6.803 12.779 600 4.712 0.677 0.320 Green light emitting layer 6.641 3.516 1000 28.518 0.316 0.619 Blue light emitting layer 6.142 14.020 700 4.986 0.148 0.152

From Tables 2 and 3, it can be seen that the flat panel display device capable of displaying both sides according to the present invention has excellent performance.

The sum of the thickness of the hole injection layer and the thickness of the transporting transport layer of the organic electroluminescent device according to the present invention as described above is different for each of the light emission color, but is reduced in the order of red, green and blue, so that the improved efficiency and color coordinate Can be improved. The organic electroluminescent device can be used to fabricate a flat panel display with high reliability.

Claims (16)

Pixel electrodes; Counter electrode; And an organic layer including a hole injection layer, a hole transporting layer, and a light emitting layer between the pixel electrode and the counter electrode, wherein the sum of the thickness of the hole injection layer and the thickness of the hole transporting layer is different for each color of light emission, and is red and green. And the sum of the thicknesses of the hole injection layer and the hole transport layer decreases according to the order of blue light emission colors. The organic electroluminescent device according to claim 1, wherein when the emission color is red, the sum of the thickness of the hole injection layer and the thickness of the hole transport layer is 2000 kPa to 2400 kPa. The organic electroluminescent device according to claim 2, wherein the hole injection layer has a thickness of 1000 kPa and the hole transport layer has a thickness of 1000 kPa to 1400 kPa. The organic electroluminescent device according to claim 1, wherein when the emission color is green, the sum of the thickness of the hole injection layer and the thickness of the hole transport layer is 1600 kPa to 2000 kPa. The organic electroluminescent device according to claim 4, wherein the hole injection layer has a thickness of 1000 kPa and the hole transport layer has a thickness of 600 kPa to 1000 kPa. The organic electroluminescent device according to claim 1, wherein when the emission color is blue, the sum of the thickness of the hole injection layer and the thickness of the hole transport layer is 1200 kPa to 1600 kPa. The organic electroluminescent device according to claim 6, wherein the hole injection layer has a thickness of 1000 kPa and the hole transport layer has a thickness of 200 kPa to 600 kPa. The method of claim 1, wherein the hole injection layer is copper phthalocyanine (CuPc), TCTA, m-MTDATA, Pani / DBSA (Polyaniline / Dodecylbenzenesulfonic acid: polyaniline / dodecylbenzenesulfonic acid) and PEDOT / PSS (Poly (3, 4- ethylenedioxythiophene) / Poly (4-styrenesulfonate): an organic electroluminescent device comprising at least one material selected from the group consisting of poly (3,4-ethylenedioxythiophene) / poly (4-styrenesulfonate)). The method of claim 1, wherein the hole transport layer is N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1-biphenyl] -4,4'diamine, N, N'- Di (naphthalen-1-yl) -N, N'-diphenyl benzidine and N, N'-diphenyl-N, N'-bis (1-naphthyl)-(1,1'-biphenyl) -4 An organic electroluminescent device comprising at least one material selected from the group consisting of 4'-diamine. The organic electroluminescent device according to claim 1, wherein the organic layer further comprises at least one layer selected from the group consisting of a hole suppression layer, an electron transport layer, an electron injection layer, and an electron suppression layer. A flat panel display device comprising the organic electroluminescent element according to any one of claims 1 to 10, wherein a pixel electrode of the organic electroluminescent element is electrically connected to a source electrode or a drain electrode of the thin film transistor. A transparent substrate having a first display portion and a second display portion; A first organic electroluminescent device positioned in the first display unit and emitting light in a first direction perpendicular to the substrate, the first organic electroluminescent device having a first pixel electrode, a first counter electrode, and a first organic layer interposed therebetween; And A second organic electroluminescent element disposed in the second display unit and emitting light in a second direction opposite to the first direction and having a second pixel electrode, a second counter electrode, and a second organic layer interposed therebetween; Including, 12. The flat panel display of claim 1, wherein at least one of the first organic electroluminescent element and the second organic electroluminescent element is an organic electroluminescent element according to any one of claims 1 to 10. The flat panel display of claim 12, wherein the first display unit and the second display unit are positioned on the same surface of the transparent substrate. The method of claim 13, wherein the first pixel electrode of the first organic electroluminescent element is a reflective electrode, the first counter electrode is a transparent electrode, the second pixel electrode of the second organic electroluminescent element is a transparent electrode, And a second counter electrode is a reflective electrode. The flat panel display of claim 12, wherein the first display unit and the second display unit are positioned on opposite surfaces of the transparent substrate, respectively. The method of claim 15, wherein the first pixel electrode and the second pixel electrode of the first organic electroluminescent device and the second organic electroluminescent device is a transparent electrode, the first counter electrode and the second counter electrode is a reflective electrode. Flat panel display device.

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