KR101900815B1 - Organic light emitting diodes - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting device, and more particularly, to an organic light emitting device having improved color reproducibility, luminous efficiency, and lifetime.
A feature of the present invention resides in a light emitting device comprising a first stack including a first light emitting film containing a dopant of a blue (B) fluorescent component, a second light emitting film containing a dopant of a yellow green (YG) And a second stack including a third light emitting film including a dopant of the second light emitting layer.
As a result, the white OLED of the present invention can realize light emission characteristics of blue (B), yellow green (YG) and red (R) while having a two stack structure.
Further, the white OLED of the present invention can improve the color stability, reduce the power consumption, and improve the stability of the organic light emitting diode in the triplet state of the organic electroluminescent diode by arranging the phosphor and the fluorescent material in a hybrid structure, 75% of the internal quantum efficiency can be utilized, and the luminous efficiency and lifetime of the white OLED can be improved.

Description

[0001] The present invention relates to organic light emitting diodes

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting device, and more particularly, to an organic light emitting device having improved color reproducibility, luminous efficiency, and lifetime.

Until recently, CRT (cathode ray tube) was mainly used as a display device. However, a flat panel display device such as a plasma display panel (PDP), a liquid crystal display device (LCD), and an organic light emitting diode (OLED) Have been widely studied and used.

Among the above flat panel display devices, an organic light emitting element (hereinafter referred to as OLED) is a self-light emitting element, and a backlight used in a liquid crystal display device which is a non-light emitting element is not required.

In addition, it has a better viewing angle and contrast ratio than liquid crystal display devices, is advantageous in terms of power consumption, can be driven by DC low voltage, has a fast response speed, is resistant to external impacts due to its solid internal components, It has advantages.

Particularly, since the manufacturing process is simple, it is advantageous in that the production cost can be saved more than the conventional liquid crystal display device.

The OLED is a self-luminous element that emits light through the organic electroluminescent diode, and the organic electroluminescent diode emits light through the organic electroluminescent phenomenon.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a band diagram of an organic light emitting diode having an emission principle based on a general organic light emitting phenomenon.

As shown in the figure, the organic light emitting diode 10 includes an anode and a cathode 21, a hole transport layer (HTL) 33 located therebetween, and an electron transport layer And an emission material layer (EML) 40 interposed between the hole transport film 33 and the electron transport film 35.

A hole injecting layer (HIL) 37 is interposed between the anode electrode 21 and the hole transporting layer 33 to improve the luminous efficiency. The cathode electrode 25 and the electron transporting layer 35 are interposed between the anode electrode 21 and the hole transporting layer 33, An electron injection layer (EIL) 39 is interposed therebetween.

When the positive and negative voltages are applied to the anode electrode 21 and the cathode electrode 25, the organic light emitting diode 10 has the positive holes of the anode electrode 21 and the positive electrode of the cathode electrode 25, Electrons are transported to the light-emitting film 40 to form excitons. When the excitons are transited from the excited state to the ground state, light is generated and is emitted by the light-emitting film 40 in the form of visible light.

Recently, a hybrid type white organic light emitting diode (LED) 10 using a fluorescent material and a phosphor simultaneously has been developed. Such a hybrid type white organic light emitting diode 10 includes a light emitting layer (B) fluorescent material, yellow (Y), and green (G) phosphorescent material are mixed to realize white (W) light emission.

However, in order to realize white light, yellow (Y) and green (G) are used instead of red (R) because the light emitting method in which three wavelength lights of blue (B), green , The light transmittance of the red (R) wavelength band after passing through the color filter is low and the color reproduction rate is low.

Recently, OLEDs have been proposed to realize white (W) light emission through a phosphorescent material in which a blue (B) fluorescent material, a red (R) dopant and a green (G) dopant are mixed. However, The life of the red (R) dopant and the green (G) dopant is different, and color shift occurs continuously.

SUMMARY OF THE INVENTION It is a first object of the present invention to provide an OLED capable of significantly increasing lifetime and efficiency and satisfying a color reproduction rate.

The second object is to improve the efficiency of the process.

In order to achieve the above-mentioned object, the present invention provides a plasma display panel comprising: a first electrode; A first hole transport layer located above the first electrode; A first luminescent film located above the first hole transport film; A first electron transport film located above the first light emitting film; A charge generation film located above the first electron transport film; A second hole transport film, a second light emitting film, a third light emitting film, and a second electron transport film sequentially disposed on the charge generation film; And a second electrode located on the second electron transport film, wherein each of the first to third light emitting films is formed of an organic light emitting material having a light emission characteristic of blue, yellow green, Device.

Here, the first light emitting film may be a light emitting film doped with a yellow (YG) phosphorescent dopant, the second light emitting film may be a light emitting film doped with a blue (B) fluorescent dopant, Wherein the first light emitting film is a light emitting film doped with a blue (B) fluorescent dopant, the second light emitting film is a light emitting film doped with a yellow green (YG) phosphorescent dopant, The film is composed of a light-emitting film doped with a red (R) fluorescent dopant.

The red has a spectral wavelength band of 550 to 650 nm, and the energy level of the second hole transporting film is higher than the triplet excited state energy level of the second light emitting layer.

The third light emitting layer may include a first region in which a red (R) dopant and a host are mixed and deposited, and a second region and a third region in which a host is deposited on both sides of the first region, The host of the second light-emitting film overlaps the deposited region.

A hole injecting film is interposed between the first electrode and the first hole transporting film, and an electron injecting film is interposed between the second electrode and the second electron transporting film.

As described above, according to the present invention, a first stack including a first light emitting film containing a dopant of a blue (B) fluorescent component, a second light emitting film containing a dopant of a yellow green (YG) (B), yellow green (YG) and red (R) light emission characteristics while forming the second stack including the second stack including the third light emitting film containing the dopant of the red (R) , And the color reproduction ratio can be improved when the color filter is applied.

In addition, the white OLED of the present invention has an effect of improving the color stability by arranging the phosphor and the fluorescent material in a hybrid structure in which the fluorescent material and the fluorescent material are located in one stack, and has an effect of lowering power consumption. An internal quantum efficiency of 75%, which is a triplet state of a diode, can be utilized, thereby improving the luminous efficiency and lifetime of a white OLED.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a band diagram of an organic light emitting diode having an emission principle by a general organic light emitting phenomenon. FIG.
Figure 2 schematically illustrates a cross-section of an OLED according to an embodiment of the present invention.
FIG. 3 is a simplified view illustrating a cross-sectional structure of an organic light emitting diode according to a first embodiment of the present invention. FIG.
FIG. 4 is a band diagram of the organic light emitting diode of FIG. 3; FIG.
FIG. 5 is a simplified cross-sectional view of an organic light emitting diode according to a second embodiment of the present invention. FIG.
FIG. 6 is a band diagram of the organic light emitting diode of FIG. 5; FIG.
FIG. 7 is a graph illustrating an emission spectrum of an organic light emitting diode according to a second embodiment of the present invention, as a function of wavelength. FIG.
8A is a cross-sectional view schematically showing a deposition process of a third light-emitting film according to a second embodiment of the present invention.
FIG. 8B is a simplified cross-sectional view of an organic light emitting diode including a third light emitting film formed by FIG. 8A; FIG.
9 is a simplified view of a cross-sectional structure of an organic light emitting diode including another third light emitting film in the organic light emitting diode according to the second embodiment of the present invention.
10A is a cross-sectional view schematically illustrating a deposition process of a second light-emitting film and a third light-emitting film according to a second embodiment of the present invention.
FIG. 10B is a simplified view illustrating a cross-sectional structure of the organic light emitting diode formed by FIG. 10A; FIG.

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

2 schematically shows a cross section of an OLED.

As shown in the figure, a plurality of driving thin film transistors DTr and organic electroluminescent diodes E are formed in the pixel region P of the OLED 100 according to the present invention.

A semiconductor layer 103 is formed on the pixel region P of the first substrate 101 of the OLED 100. The semiconductor layer 103 is made of silicon and the central portion of the semiconductor layer 103 is formed of an active And source and drain regions 103a and 103c doped with a high concentration of impurities on both sides of the region 103b and the active region 103b.

A gate insulating layer 105 is formed on the semiconductor layer 103.

The gate electrode 107 and the gate wiring extending in one direction are formed on the gate insulating film 105 in correspondence with the active region 103b of the semiconductor layer 103 and not shown in the drawing.

The first interlayer insulating film 109a and the gate insulating film 105 under the first interlayer insulating film 109a are formed on the upper surface of the gate electrode 107 and the gate wiring (not shown) And first and second semiconductor layer contact holes 111a and 111b that respectively expose source and drain regions 103a and 103c located on both sides of the semiconductor layer 103b.

Next, upper portions of the first interlayer insulating film 109a including the first and second semiconductor layer contact holes 111a and 111b are separated from each other by a source exposed through the first and second semiconductor layer contact holes 111a and 111b, And source and drain electrodes 113 and 115 which are in contact with the source and drain regions 103a and 103c, respectively.

And a drain contact hole 117 exposing the drain electrode 115 to the upper portion of the first interlayer insulating film 109a exposed between the source and drain electrodes 113 and 115 and the two electrodes 113 and 115, An insulating film 109b is formed.

At this time, the semiconductor layer 103 including the source and drain electrodes 113 and 115 and the source and drain regions 103a and 103c contacting the electrodes 113 and 115 and the gate insulating film The gate electrode 105 and the gate electrode 107 constitute a driving thin film transistor DTr.

At this time, although not shown in the drawing, data lines (not shown) are formed which cross the gate wiring (not shown) and define the pixel region P. The switching thin film transistor (not shown) has the same structure as the driving thin film transistor DTr and is connected to the driving thin film transistor DTr.

The switching and driving thin film transistor (not shown) DTr is shown as an example of a top gate type in which the semiconductor layer 103 is a polysilicon semiconductor layer. As a variation thereof, the amorphous Or may be formed of a bottom gate type made of silicon nitride.

The first electrode 211, the organic light emitting layer 213, and the second electrode 215 constituting the organic electroluminescent diode E are sequentially formed on the second interlayer insulating film 109b, Respectively.

Here, the first electrode 211 is connected to the drain electrode 115 of the driving thin film transistor DTr through the drain contact hole 117 of the second interlayer insulating film 109b.

In this case, the first electrode 211 is formed of indium-tin-oxide (ITO), which is a relatively high work function value, to serve as an anode electrode, and the second electrode 215 is formed of a cathode cathode is made of a metal material having a relatively low work function value.

The organic light emitting layer 213 includes a hole transport film 221a and 221b in FIG. 3, a hole injection film 222 in FIG. 3, a light emitting film 223a, 223b and 223c in FIG. 3, 224a, 224b, and an electron injection film (225 in Fig. 3).

Since the light emitted from the organic light emitting layer 213 must be transmitted through the second electrode 215, the second electrode 215 is formed by forming a transparent conductive material thick on the semitransparent metal film on which a metal material having a low work function is deposited thinly Layer structure.

When a predetermined voltage is applied to the first electrode 211 and the second electrode 215 in accordance with a selected color signal, the OLED 100 emits light from the holes injected from the first electrode 211 and the holes injected from the second electrode 215 The excited electrons are transported to the organic light emitting layer 213 to form an exciton. When the excitons transit from the excited state to the ground state, light is emitted and emitted in the form of visible light.

At this time, the light emitted from the organic light emission passes through the second electrode 215 and exits to the outside, so that the OLED 100 realizes an image by the top emission method.

The first electrode 211 is formed for each pixel region P and a bank 119 is located between the first electrodes 211 formed for each pixel region P. [

The OLED 100 according to the present invention has improved color reproducibility as compared with the conventional OLED 100 and further improves the luminous efficiency and lifetime of the OLED 100 compared with the conventional OLED 100. This is because the organic EL layer 213 of the organic electroluminescent diode E This is because the luminous efficiency is improved.

FIG. 3 is a simplified diagram illustrating a cross-sectional structure of an organic light emitting diode according to a first embodiment of the present invention, and FIG. 4 is a band diagram of the organic light emitting diode of FIG.

The organic light emitting diode E includes a first electrode 211 which is an anode electrode and a second electrode 211 which is a cathode electrode, 215, and a first stack 229a, a charge generation layer (CGL) 227, and a second stack 229b stacked between the first electrode 211 and the second electrode 215 And an organic light emitting layer 213.

Here, holes and electrons are injected from the charge generation film 227 through the adjacent second hole transporting film 221b and the first electron transporting film 224a of the first and second stacks 229a and 229b, respectively, 223a, 223b, and 223c.

At this time, the charges generated in the charge generation film 227 are combined with the holes and electrons injected from the first electrode 211 and the second electrode 215 to emit light.

At this time, the charge generating film 227 can use various organic materials having strong electron donor and electron acceptor characteristics. Basically all materials used for P-type and N-type bonding are available.

The charge generation film 227 is preferably formed of P-type and N-type organic semiconductors in order to facilitate the deposition and improve the interfacial characteristics.

A P-type organic semiconductor is a donor capable of absorbing light to form an exciton and to separate electrons into holes and electrons at junctions with N-type organic semiconductors. At this time, the N type organic semiconductor can be a material that can accept electrons easily, that is, a material that can be easily reduced as an acceptor.

The first stack 229a includes a first hole transport layer (HTL) 221a, a first light emitting layer 223a, a first electron transport layer 223b, and a second electron transport layer 223b between the first electrode 211 and the charge generation layer 227. [ And a second stack 229b are sequentially stacked between the charge generation film 227 and the second electrode 215. The second stack 229b includes a second hole transport film 221b, A second light emitting film 223b, a third light emitting film 223c, and a second electron transport film 224b are stacked.

At this time, a hole injection layer (HIL) 222 is interposed between the first electrode 211 and the first hole transport layer 221a to improve the luminous efficiency, and the second electrode 215 and the second hole transport layer A second electron injection layer (EIL) 225 is interposed between the first and second hole transporting films 224b.

Here, the first light emitting film 223a is formed of a single light emitting film formed by doping phosphorescence yellow green with a host, and the second light emitting film 223b is formed of a blue (B) a dopant of a fluorescent component, and the third light emitting film 223c is composed of a light emitting film containing a dopant of a red (R) fluorescent component in one host.

That is, the organic electroluminescent diode (E) of the present invention has light emission characteristics of blue (B), yellow green (YG) and red (R).

Accordingly, in driving the white OLED (100 in FIG. 2) including the organic electroluminescent diode E of the present invention, the first light emitting film 223a, the second light emitting film 223b, and the third light emitting film 223c And white light is realized by mixing light emitted.

Since the red (R) fluorescent material has a spectral wavelength band of 550 to 650 nm, the white light realized through the white OLED 100 of the present invention has a wavelength band of blue (B), red (R) To realize a white light having a wide wavelength band of 450 to 650 nm.

The yellow-green (YG) emission characteristics are high because the luminosity characteristics are high, so that the spectral characteristics of the white light realized from the white OLED 100 according to the embodiment of the present invention can be improved.

Meanwhile, the organic electroluminescent diode E according to the present invention can improve the color stability and lower the power consumption by arranging the phosphor and the fluorescent material in a hybrid structure in which the phosphor and the fluorescent material are located in one stack 229a and 229b .

Particularly, it is possible to utilize the internal quantum efficiency of 75% which is the triplet state of the organic electroluminescent diode (E), so that the luminous efficiency and lifetime of the white OLED 100 can be improved.

FIG. 5 is a simplified diagram illustrating a cross-sectional structure of an organic light emitting diode according to a second embodiment of the present invention, and FIG. 6 is a band diagram of the organic light emitting diode of FIG.

As shown in the drawing, the organic light emitting diode 213 according to the second embodiment of the present invention will be described in more detail. The organic light emitting diode E includes a first electrode 211 as an anode electrode, a second electrode 211 as a cathode electrode 215, and a first stack 229a, a charge generation layer (CGL) 227, and a second stack 229b stacked between the first electrode 211 and the second electrode 215 And an organic light emitting layer 213.

Here, holes and electrons are injected from the charge generating film 227 through the adjacent second hole transporting film 221b and the first electron transporting layer 224a of the first and second stacks 229a and 229b to the light emitting film 223a , 223b, and 223c.

At this time, the charges generated in the charge generation film 227 are combined with the holes and electrons injected from the first electrode 211 and the second electrode 215 to emit light.

At this time, the charge generating film 227 can use various organic materials having strong electron donor and electron acceptor characteristics. Basically all materials used for P-type and N-type bonding are available.

For good deposition and good interface characteristics, the charge generating film is preferably formed of P-type and N-type organic semiconductors.

The P-type organic semiconductor is a donor capable of absorbing light to form an exciton and to separate electrons into holes and electrons at junctions with N-type organic semiconductors . At this time, the N type organic semiconductor can be a material that can accept electrons easily, that is, a material that can be easily reduced as an acceptor.

The first stack 229a includes a first hole transport film 221a, a second light emitting film 223b and a first electron transport film 224a between the first electrode 211 and the charge generating film 227 And the second stack 229b includes a second hole transport film 221b, a first light emitting film 223a, a third light emitting film 223b, a second light emitting film 223b, A second electron transport film 223c, and a second electron transport film 224b.

A first hole injection layer 222 is interposed between the first electrode 211 and the first hole transport layer 221a and a second hole injection layer 222 is formed between the second electrode 215 and the second hole transport layer The second electron injection film 225 is interposed between the first and second electron injection films 224a and 224b.

Here, a second light emitting film 223b composed of a light emitting film containing a dopant of a blue (B) fluorescent component is contained in one host in the first stack 229a, and a phosphorescence yellow green) doped with a red (R) fluorescent component and a third light emitting layer 223c containing a dopant of a red (R) fluorescent component in one host are included in the second stack 229b.

That is, the organic electroluminescent diode (E) of the present invention has light emission characteristics of blue (B), yellow green (YG) and red (R).

Accordingly, in driving the white OLED (100 in FIG. 2) including the organic electroluminescent diode E of the present invention, the first light emitting film 223a, the second light emitting film 223b, and the third light emitting film 223c And white light is realized by mixing light emitted.

Since the red (R) fluorescent material has a spectral wavelength band of 550 to 650 nm, the white light realized through the white OLED 100 of the present invention has a wavelength band of blue (B), red (R) To realize a white light having a wide wavelength band of 450 to 650 nm.

The yellow-green (YG) emission characteristics are high because the luminosity characteristics are high, so that the spectral characteristics of the white light realized from the white OLED 100 according to the embodiment of the present invention can be improved.

Here, the organic light emitting diode E of the present invention may be configured such that the third light emitting film 223c of the second stack 229b is made of a fluorescent material and the first light emitting film 223a is made of yellow The green (YG) luminescent film is made of a phosphorescent material so that the hole and the electron are recombined in the third luminescent film 223c made of the red (R) luminescent film, and the triplet The excitons are moved to the first luminescent film 223a made of the phosphor film as much as possible by energy transfer to obtain phosphorescence emission of yellow green (YG), thereby improving luminous efficiency.

That is, when holes and electrons form excitons in the light emitting films 223a and 223c, a singlet state and a triplet state are generated at a ratio of 3: 1. Here, a single-termed exciton can emit light and transition to a ground state, which is called fluorescence. However, it is prohibited that the triplet exciton transits light to a single ground state.

However, triplet excitons can also emit light by a perturbation such as spin-orbit coupling, which is called phosphorescence.

Here, by recombination of holes and electrons, phosphorescence allows all excitons formed in either single or triplet excited states to participate in light emission.

In contrast, only about 25% of the excitons in the fluorescent devices can produce fluorescent light emission from a singlet excited state. The remaining excitons generated in the lowest triplet excited state in a fluorescent device can not be converted to higher energy single-excited states in which the fluorescence is produced.

Therefore, the organic electroluminescent light emitting diode E of the present invention moves the triplet exciton generated in the third light emitting film 223c made of the fluorescent light emitting film to the first light emitting film 223a made of the phosphorescent film, ), Thereby improving the luminous efficiency of the organic electroluminescent diode (E).

At this time, the second hole transporting film 221b and the second electron transporting film 224b of the present invention are set to have an energy level higher than the energy level of the excited state of the triplet excitons of the first light emitting film 223a, , And the second hole transport film 221b is set to be higher by about 0.001 to 0.5 eV than the energy level of the excited state of the triplet exciton of the first light emitting film 223a.

Since the energy level of the second hole transporting film 221b and the second electron transporting film 224b is higher than that of the first light emitting film 223a, the triplet excitons of the first light emitting film 223a are formed in the second hole transporting film 221b and the second electron transport film 224b to prevent the luminous efficiency from dropping.

The first electron transport film 224a and the first hole transport film 221a are set to an energy level higher than the energy level of the excited state of the triplet triplet exciton of the first light emitting film 223a by 0.001 to 0.5 eV .

As described above, the first and second hole transporting films 221a and 221b and the first and second electron transporting films 224a and 224b on the upper and lower surfaces of the first and third light emitting films 223a and 223c, respectively, By increasing the energy level, it is possible to prevent each of the mono-excitons and the triplet excitons from moving to the upper and lower interfaces of the first and third light-emitting films 223a and 223c, thereby maximizing the light emission.

Accordingly, since the first and second hole transporting films 221a and 221b and the first and second electron transporting films 224a and 224b have a high triplet energy, the triplet exciton is extinguished Triplet-triplet collision annihilation in a triplet-triplet collision annihilation.

Thus, a delayed fluorescence is produced by one single exciton having a lifetime that is much longer than the lifetime of the fluorescence of the directly excited single-exciton. The emission efficiency of the organic electroluminescent diode E can be further improved by the delayed fluorescent light.

Therefore, in the present invention, the light emitting efficiency of the organic electroluminescent diode (E) is improved by 20% or more and the lifetime is increased by 50% or more within the same luminance.

Particularly, the organic electroluminescent diode E according to the present invention has a structure in which blue (B), yellow green (YG), and blue (B) light emitted from the first light emitting film 223a, the second light emitting film 223b, and the third light emitting film 223c, White light is realized by mixing red (R) light, thereby improving the color reproduction rate.

FIG. 7 is a graph illustrating emission spectra of an organic light emitting diode according to a second embodiment of the present invention. FIG.

Here, C1 represents a spectrums of wavelengths of organic light emitting diodes that emit white (W) light by mixing blue (B) fluorescent material, yellow (Y), and green (YG) (E in FIG. 5) that emits white (W) light by mixing blue (B) and red (R) phosphors with yellow (YG) phosphors according to an embodiment of the present invention Respectively.

Referring to FIG. 7, it can be seen that C1 can not implement the spectrum of the red (R) wavelength band.

When the white light emitted from the organic electroluminescent diode passes through red (R), green (G) and blue (B) color filters (not shown), the transmittance of light passing through the red (R) , The color of red (R) is lost a lot.

Therefore, the color reproduction rate is low.

On the other hand, it can be seen that all of the blue (B), yellow green (YG) and red (R) wavelength peaks have a uniform peak and a high peak value by further including a red (R) fluorescent substance as in the C2 embodiment of the present invention .

Therefore, the color reproduction rate in the corresponding color filter (not shown) is improved.

Particularly, since the red (R) fluorescence component according to the embodiment of the present invention has a spectral wavelength band of 550 to 650 nm, the white light realized through the white OLED (100 in FIG. 2) according to the embodiment of the present invention is blue B), a red (R), and a green (G) wavelength band.

Meanwhile, the first to third light emitting films 223a, 223b, and 223c according to the exemplary embodiment of the present invention are formed through a vacuum thermal deposition process. In the vacuum thermal deposition process, an organic material having a desired color is deposited (Not shown), the evaporation source (not shown) is heated in a chamber (not shown) where a vacuum is maintained, and the evaporated organic material is discharged through an outlet (not shown) (Not shown) to form the first to third light emitting films 223a, 223b, and 223c.

At this time, the first to third light emitting films 223a, 223b, and 223c are usually composed of a host-dopant system. In general, the host has a high energy gap, and the exciton formed in the host is energy transfer to a dopant having a lower energy gap.

That is, the first light emitting film 223a is formed by doping phosphorescence yellow green together with a phosphorescent yellow green (YG) dopant in one host, and the second light emitting film 223b is formed by doping One host includes a dopant of a blue (B) fluorescent component, and the third light emitting film 223c includes a dopant of a red (R) fluorescent component in one host.

At this time, the hosts of the first light emitting film 223a and the third light emitting film 223b may be different species, or may be made of the same species.

FIG. 8A is a cross-sectional view schematically showing a deposition process of a third light emitting film according to a second embodiment of the present invention, FIG. 8B is a cross-sectional view of a third light emitting film formed by FIG. Fig.

Here, the vacuum thermal deposition method is a method in which the crucibles 310a, 310b, and 310c containing the organic materials 330a, 330b, and 340 in the form of powder, the heaters 310a, 310b, and 310c provided in the crucibles 310a, 310b, and 310c, : ≪ / RTI > not shown).

As shown in FIG. 8A, the vacuum deposition equipment has a chamber 300 defining an enclosed reaction area A as an essential component, and a crucible unit 310 is provided therein.

Here, the crucible unit 310 includes first to third crucibles 310a, 310b, and 310c. The second crucible 310b located at the center contains a dopant 340 of a red (R) The first and second crucibles 310a and 310c located on both sides of the second crucible 310b contain first and second hosts 330a and 330b, respectively.

A dopant 340 of a red fluorescent material and a heater (not shown) for heating the hosts 330a and 330b are provided at the sides of each of the first to third crucibles 310a, 310b, and 310c do.

Here, the reaction region A is always kept in a vacuum state, and is provided with a substrate 101 on which a first electrode (211 in FIG. 5) as an anode electrode is formed, and arranged so as to face the crucible unit 310.

A mask M having an opening G in a region corresponding to a region where the dopant 340 and the host 330a or 330b are to be deposited is provided on the substrate 101. [

At this time, the substrate 101 is moved in the horizontal direction while being fixed by the substrate holder 350.

That is, the vacuum deposition apparatus of the present invention is a scan type in which the substrate 101 is horizontally moved, and the first to third crucibles 310a, 310b, 310c are fixed and deposited.

Therefore, the dopant 340 of the red (R) fluorescent component evaporated from the first to third crucibles 310a, 310b and 310c and the first and second hosts 330a and 330b are deposited in different deposition areas D1 , D2, D3).

The dopant 340 of the red fluorescence component evaporated from the second crucible 310b has a first deposition region D1 and the first host 330a evaporated from the first crucible 310a has a second deposition And the second host 330b having the region D2 and evaporated from the third crucible 310c has the third deposition region D3.

8B, the organic light emitting diode E according to the embodiment of the present invention includes a third light emitting layer 223c, a second deposition region D2 in which the first host 330a is deposited, A third deposition region D3 in which a second host 330b is deposited and a first deposition region D1 in which a dopant 340 of a red fluorescence component is deposited.

At this time, a region where the first deposition region D1, the second deposition region D2, the first deposition region D1, and the third deposition region D3 overlap with each other is generated, so that the third light-emitting film 223c The first host region h1 in which the first host 330a is deposited and the second host region h2 in which the second host 330b is deposited and the first and second host regions h1 and h2, (R) dopant and a host region R_DH in which the dopant 340 of the (R) fluorescent component and the first and second hosts 330a and 330b are mixed and deposited.

Here, the third light emitting film 223c emits red light through the red (R) dopant and the host region R_DH.
9 is a simplified view of a cross-sectional structure of an organic light emitting diode including another third light emitting layer in the organic light emitting diode according to the second embodiment of the present invention.

9, the organic light emitting diode E according to the embodiment of the present invention includes a third light emitting layer 223c, a second deposition region D2 on which a host is deposited, and a second deposition region D2 on which a host is deposited. And a first deposition region D1 in which a dopant is deposited.

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At this time, a region where the first deposition region D1 and the second deposition region D2 overlap with each other occurs, so that the third light emitting film 223c is formed by the host region h and the dopant of the red (R) (R) dopant and a host region (R_DH) mixed with each other.

Here, the third light emitting film 223c emits red light through the red (R) dopant and the host region R_DH.

This is possible by forming the crucible unit (310 in FIG. 8A) of the vacuum thermal evaporation apparatus only with the first crucible containing the dopant of the red (R) fluorescent component and the second crucible containing the host.

In addition, the host of the second light emitting film 223b and the third light emitting film 223c of the present invention may be made of the same species, which will be described in more detail.

10A is a cross-sectional view schematically illustrating a deposition process of a second light-emitting film and a third light-emitting film according to a second embodiment of the present invention. FIG. 10B is a cross-sectional view of the organic light- Fig.

As shown in FIG. 10A, the vacuum deposition equipment has a chamber 300 defining an enclosed reaction zone A1 and A2 as an essential component, and the first and second crucible units 310 and 320 .

Here, the reaction zone is divided into first and second reaction zones A1 and A2, and first and second crucible units 310 and 320 are provided in the first and second reaction zones A1 and A2, respectively The first reaction zone A1 is provided with a substrate 101 on which an anode electrode 211 (see FIG. 5) is formed, and is arranged to face the first crucible unit 310.

A mask M is provided on the substrate 101 with dopants 340a and 340b and openings G in regions corresponding to the regions where the hosts 330a, 330b and 330c are to be deposited.

The first crucible unit 310 includes first to third crucibles 310a, 310b and 310c and the second crucible unit 320 includes first and second crucibles 320a and 320b. The second crucible 310b positioned in the center of the first crucible unit 310 located in the first reaction zone A1 contains the dopant 340a of the yellow green phosphor YG and the second crucible 310b, The first and third crucibles 310a and 310c located on both sides of the first crucible 310a and the second crucible 310c are respectively accommodated in the first and second hosts 330a and 330b.

The first crucible 320a of the second crucible unit 320 located in the second reaction zone A2 contains the dopant 340b of the red fluorescent material and the one of the first crucible 320a, The third crucible 320b is located in the second crucible 320b.

At this time, the substrate 101 is moved in the horizontal direction while being fixed by the substrate holder 350.

That is, in the vacuum deposition apparatus of the present invention, the substrate 101 horizontally moves in the first and second reaction regions A1 and A2, and the first and second crucible units 310 and 320 are fixed, Scan type.

A dopant 340a of a yellow green (YG) phosphorescent material evaporated from the second crucible 310b of the first crucible unit 310 is formed on the substrate 101 in the first reaction zone A1, The first host 330a evaporated from the first crucible 310a is deposited in the second deposition region D2 and the second host 320b evaporated from the third crucible 310c And is deposited in the third deposition region D3.

The substrate 101 is then moved to the second reaction zone A2 so that the dopant 340b of the red fluorescence component evaporated from the first crucible 320a of the second crucible unit 320 reaches the fourth deposition And the third host 330c, which is evaporated from the second crucible 320b, is deposited in the fifth deposition region D5.

10B, the organic light emitting diode E according to the embodiment of the present invention includes a first light emitting layer 223a, a second deposition region D2 in which the first host 330a is deposited, A third deposition region D3 in which a second host 330b is deposited and a first deposition region D1 in which a dopant 340a of a yellow green phosphor is doped, A fourth deposition region D4 in which a dopant 340b of a red fluorescence component is deposited and a fifth deposition region D5 in which a third host 330c is deposited.

At this time, since the first deposition region D1 and the second deposition region D2, and the first deposition region D1 and the third deposition region D3 overlap each other, The first host region h1 in which the first host 330a is deposited and the second host region h2 in which the second host 330b is deposited and the first and second host regions h1 and h2, A green (YG) dopant and a host region GY_DH in which a dopant 340a of a green (YG) phosphorescent component and a first and a second host 330a and 330b are mixed and deposited.

Here, the first light emitting film 223a emits light of yellow green (YG) through the yellow green (YG) dopant and the host region GY_DH.

The third light emitting film 223c includes a red (R) dopant and a host region R_DH mixed with a dopant 340b of a red (R) fluorescent component and a third host 330c, And a third host region h3 on which the second host region 330c is deposited.

At this time, the red (R) dopant and the host region R_DH of the second host region h2 of the first light emitting film 223a and the third light emitting film 223c may be superposed and deposited.

The second host 330b of the second host region h2 of the first light emitting film 223a may be deposited on the red (R) dopant of the third light emitting film 223c and the host region R_DH.

As described above, the white OLED (100 in FIG. 2) of the present invention can realize the light emission characteristics of blue (B), yellow green (YG) and red (R) while having two stacks (229a and 229b) When the filter is applied, the color reproduction rate can be improved.

In addition, the white OLED of the present invention (100 in FIG. 2) can improve the color stability, reduce the power consumption, and reduce the power consumption by arranging the phosphor and the fluorescent material in a hybrid structure in which the fluorescent material is located in one stack 229b. It is possible to utilize the internal quantum efficiency of 75% which is the triplet state of the organic electroluminescent diode (E), thereby improving the luminous efficiency and lifetime of the white OLED (100 in FIG. 2).

The present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention.

211: first electrode, 215: second electrode,
The first and second electron transporting layers 224a and 224b are formed on the first and second electron transporting layers 223a and 223b, 225: electron injecting film)
229a, 229b: first and second stacks
E: Organic light emitting diode

Claims (8)

A first electrode;
A first hole transport layer located above the first electrode;
A first luminescent film located above the first hole transport film;
A first electron transport film located above the first light emitting film;
A charge generation film located above the first electron transport film;
A second hole transport film, a second light emitting film, a third light emitting film, and a second electron transport film sequentially disposed on the charge generation film;
The second electrode located on the second electron transport film
Wherein the third light emitting layer comprises a first region in which a red (R) fluorescent dopant and a host are mixed and deposited, and a second region in which a host is deposited on one side of the first region,
Wherein the first light emitting film is a light emitting film doped with a blue (B) fluorescent dopant, and the second light emitting film comprises a light emitting film doped with a yellow green (YG) phosphorescent dopant.
delete delete The method according to claim 1,
And the third light-emitting film has a spectral wavelength band of 550 to 650 nm.
The method according to claim 1,
Wherein the energy level of the triplet excited state of the second hole transport film is higher than the energy level of the triplet excitation state of the second light emitting film.
The method according to claim 1,
And a third region where a host is deposited on the other side of the first region.
The method according to claim 1,
Wherein the second light emitting layer comprises a first region in which a host is mixed and deposited with a yellow green (YG) phosphorescent dopant, and a second region and a third region in which a host is deposited on both sides of the first region.
The method according to claim 1,
Wherein a hole injection film is interposed between the first electrode and the first hole transporting film, and an electron injecting film is interposed between the second electrode and the second electron transporting film.

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