KR101400058B1 - Organic Light Emitting Display Device - Google Patents

Abstract

The present invention relates to a substrate; A thin film transistor formed on the substrate; A first electrode formed on the thin film transistor; A second stack including a first stack including a first light emitting layer formed on the first electrode and emitting a first color, a second light emitting layer formed on the first electrode and emitting a second color, An organic light emitting layer including a CGL (Charge Generation Layer) layer formed between the first stack and the second stack; (First peak wavelength) of the first color on a photoluminescence (PL) spectrum determined according to a dopant characteristic of the first and second light emitting layers, and a second electrode formed on the organic light emitting layer, (Second peak wavelength) of the first color on the emittance spectrum determined according to the optical characteristics of the organic light emitting device, and is located in a shorter wavelength region than the peak wavelength (second peak wavelength) of the first color on the photoluminescence (Fourth peak wavelength) of the first color is located in a shorter wavelength or a longer wavelength region than the peak wavelength of the second color (fourth peak wavelength) in the emittance spectrum ,
According to the present invention, it is possible to improve the matching of the PL spectrum and the emittance spectrum, thereby reducing the color shift phenomenon as the viewing angle increases, thereby improving the color viewing angle characteristics.

Description

[0001] The present invention relates to an organic light emitting display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display capable of improving a color viewing angle.

Generally, a light emitting device can be classified into an organic light emitting display device using an organic material to form a light emitting layer and an inorganic light emitting display device using an inorganic material to form a light emitting layer. In the organic light emitting display device, an electron injected from an electron injection electrode (cathode) and a hole injected from a hole injection electrode (anode) Emitting device that emits light when excitons emit energy and has advantages such as low power driving, self light emission, wide viewing angle, realization of high resolution and full color, and fast response speed.

Such organic light emitting display devices have recently been recognized as one of the most important display devices due to the development of an organic light emitting display device capable of emitting white light due to the wide application fields such as backlight or illumination.

The organic light emitting diode displays a white color by using a single layer light emitting method, a multilayer light emitting method, a color conversion method, and a device laminating method. Among these methods, light is emitted in various layers, And a white color is realized by the light emitting layer.

Specifically, in the case of an organic light emitting display according to a multilayered light emitting system having a two stack structure, as shown in FIG. 1, emits light of an EL (Electroluminescent) spectrum having two peaks on the outside.

However, the above-described conventional OLED display has the following problems.

FIG. 1 is a graph showing a PL spectrum of the organic light emitting display according to the related art in which the EL spectrum and the emittance spectrum vary with the viewing angle, B) and the yellow-green light (YG).

1, the EL spectrum 30 obtained by spectral analysis of the final light emitted by the organic light emitting display device has a PL spectrum 10 as a spectrum of light emitted from the light emitting layer, a thickness of a layer constituting the organic light emitting layer And is expressed as a product of an emittance spectrum (20) that varies depending on optical characteristics.

As shown in the PL spectrum (10), it consists of a light emitting layer emitting blue peak wavelength (B PL) and a light emitting layer emitting yellow peak wavelength (YG PL), and emits white light. However, the white light of such a configuration has a problem that the luminance reduction characteristics of the blue light and the sulfur green light are different depending on the viewing angle, and the color viewing angle characteristic is deteriorated.

That is, as shown in the EL spectrum 30 and FIG. 2, as the viewing angle increases from 0 ° to 60 °, the luminance of the blue light decreases sharply, whereas the luminance of the yellow green decreases relatively slowly. Therefore, a color shift phenomenon occurs between the white light realized at the front (viewing angle 0 °) and the white light realized at the side toward the side (viewing angle increases), which is a problem (deterioration of the color viewing angle characteristic).

Further, as can be seen from the EL spectrum 30, the intensity of the red light is smaller than the intensity of the blue and green light. Therefore, the current density of the red sub-pixel is increased in order to obtain a sufficient luminance, thereby increasing the voltage and decreasing the luminous efficiency of the panel.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to improve the color viewing angle characteristics and improve the luminous efficiency of the panel.

It is another object of the present invention to provide an organic light emitting display having improved color reproducibility.

In order to achieve the above-mentioned object, the present invention provides a semiconductor device comprising: a substrate; A thin film transistor formed on the substrate; A first electrode formed on the thin film transistor; A second stack including a first stack including a first light emitting layer formed on the first electrode and emitting a first color, a second light emitting layer formed on the first electrode and emitting a second color, An organic light emitting layer including a CGL (Charge Generation Layer) layer formed between the first stack and the second stack; (First peak wavelength) of the first color on a photoluminescence (PL) spectrum determined according to a dopant characteristic of the first and second light emitting layers, and a second electrode formed on the organic light emitting layer, (Second peak wavelength) of the first color on the emittance spectrum determined according to the optical characteristics of the organic light emitting device, and is located in a shorter wavelength region than the peak wavelength (second peak wavelength) of the first color on the photoluminescence (Third peak wavelength) of the second color is located in a shorter wavelength or a longer wavelength region than a peak wavelength (fourth peak wavelength) of the second color on the emittance spectrum .

At this time, the difference between the peak wavelength of the first color and the peak wavelength of the first color on the emittance spectrum on the photoluminescence (PL) spectrum is 10 nm or less, and the difference between the peak wavelength of the first color on the photoluminescence (PL) spectrum And the difference between the peak wavelength of the second color and the peak wavelength of the second color on the emittance spectrum is ± 10 nm or less.

The first color is blue, and the second color is yellow and green.

The dopant concentration of the second light emitting layer is 10% or more and 25% or less of the host.

And the dopant material of the second light emitting layer has a peak wavelength of the second color having a wavelength of 540 nm or more and 575 nm or less.

The color coordinate change amount? U'v 'on the CIE 1976 color coordinate system in the viewing angle direction of 0 ° to 60 ° of the light emitted from the organic light emitting display device is 0.02 or less.

And an overcoat layer and an optical compensation layer between the thin film transistor and the first electrode.

And the refractive index of the optical compensation layer has a value of 1.8 or more and 2.3 or less.

And the thickness of the optical compensation layer has a value of not less than 1100 angstroms and not more than 2500 angstroms.

(Full Width at Half Maximum) of the peak wavelength of the second color (the third peak wavelength) on the light emission (PL) spectrum is 80 nm or more.

According to the present invention, the following effects can be obtained.

The present invention has an effect of improving the color viewing angle characteristic by reducing the color shift phenomenon with the increase of the viewing angle by improving the matching of the PL spectrum and the emittance spectrum.

Further, there is an effect of improving the luminous efficiency of the red light in the EL spectrum, thereby reducing the voltage and improving the luminous efficiency of the panel.

Further, the full width at half maximum of the peak wavelength on the PL spectrum is widened, and the color reproduction ratio and the luminous efficiency are increased.

FIG. 1 is a view showing a PL spectrum in which the EL spectrum and the emittance spectrum which change according to the viewing angle in the conventional organic light emitting display device, and the substantially no change according to the viewing angle.
FIG. 2 is a graph showing a decrease in luminance due to an increase in viewing angle of blue light (B) and yellow green light (YG) in the conventional OLED display of FIG.
3 is a cross-sectional view of an OLED display according to an embodiment of the present invention.
4 is a view illustrating a structure of an organic light emitting layer of an organic light emitting display according to an embodiment of the present invention.
5 is a graph showing a PL spectrum and an emittance spectrum of an organic light emitting diode display according to the present invention.
FIG. 6 is a graph illustrating characteristics of an organic light emitting display according to an embodiment of the present invention having an optical compensation layer having a thickness of 1600A after increasing doping amount of a sulfur-doped green dopant to 14% and 20%.
FIG. 7 is a graph showing the amount of color coordinate change according to the viewing angle in Experimental Example 1 of FIG.
8 is a graph showing an EL spectrum according to the doping amount in Experimental Example 1 of FIG.
FIG. 9 is a graph illustrating the characteristics of the organic light emitting diode display according to the present invention in which an optical compensation layer having a thickness of 2200 A is formed, after increasing the doping amount of the sulfur-green dopant to 14% and 20%.
FIG. 10 is a graph showing the amount of color coordinate change according to the viewing angle in Experimental Example 2 of FIG.
11 is a graph showing an EL spectrum according to doping amount in Experimental Example 2 of FIG.
FIG. 12 is a graph illustrating the characteristics of the organic light emitting diode display according to the present invention in which the optical compensation layer is not formed after increasing the doping amount of the sulfur-doped green dopant to 14% and 20%.
13 is a graph showing the amount of color coordinate change according to the viewing angle in Experimental Example 3 of FIG.
14 is a graph showing an EL spectrum according to the doping amount in Experimental Example 3 of FIG.
FIG. 15 is a diagram showing the intensity variation amount according to the half width variation on the PL spectrum. FIG.
FIG. 16 is a chart for analyzing the luminance and current density per unit area of the spectra shown in FIG. 15 on an RGB channel.
FIG. 17 is a diagram showing the amount of intensity variation according to the change of the YG peak wavelength. FIG.
FIG. 18 is a chart for analyzing the efficiency and the current density according to the change in the peak luminance of each of the R, G, and B channels after transmission of the color filter (CF) of the spectrum shown in FIG.

Hereinafter, the organic light emitting diode display according to the present invention will be described in detail with reference to the drawings.

In describing an embodiment of the present invention, when it is stated that a structure is formed "on" or "under" another structure, such a substrate is not limited to the case where these structures are in contact with each other, The present invention is not limited thereto.

FIG. 3 is a cross-sectional view of an organic light emitting display according to an exemplary embodiment of the present invention, and FIG. 4 is a view illustrating a structure of an organic light emitting layer of an organic light emitting display according to an exemplary embodiment of the present invention.

3, the OLED display 100 according to an exemplary embodiment of the present invention includes a substrate 110, a thin film transistor (TFT), an overcoat layer 150, an optical compensation layer 155, A first electrode layer 160, a bank layer 170, an organic light emitting layer 180, and a second electrode 190. At this time, the thin film transistor TFT includes a gate electrode 115, a gate insulating layer 120, a semiconductor layer 131, a source electrode 133, a drain electrode 135, a first passivation layer 140, An organic light emitting layer 180 and a second electrode 190. The organic light emitting layer 180 is formed on the first electrode 160,

The substrate 110 may be formed of glass or a transparent plastic.

The gate electrode 115 is formed on the substrate 110 and is connected to the gate line GL. The gate electrode 115 may be formed of a material selected from the group consisting of Mo, Al, Cr, Au, Ti, Ni, Ne, Or may be a multilayer of one or alloys thereof.

The gate insulating layer 120 may be formed on the gate electrode 115 and may be a silicon oxide layer (SiOx), a silicon nitride layer (SiNx), or a multilayer thereof.

The semiconductor layer 131 is formed on the gate insulating layer 120 and may include amorphous silicon or polycrystalline silicon crystallized therefrom. The etch stopper (not shown) may be formed on the semiconductor layer 131 to protect the semiconductor layer 131, but it may be omitted depending on the case.

The source electrode 133 and the drain electrode 135 may be formed on the semiconductor layer 131. The source electrode 133 and the drain electrode 135 may be formed of a single layer or a multilayer and may be formed of at least one of Mo, Al, Cr, Au, Ti, ), Neodymium (Nd), and copper (Cu), or an alloy thereof.

The first passivation layer 140 is formed on the source electrode 133 and the drain electrode 135 and may be a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof.

A color filter 145 is formed on the first passivation layer 140 on the red sub-pixel, the blue sub-pixel, and the green sub-pixel, and converts the white light emitted from the organic light-emitting layer into red, .

The overcoat layer 150 is formed on the color filter 145 and may be an acrylic resin or a polyimide resin, a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof.

The optical compensation layer 155 is formed on the overcoat layer 150 and may be formed of a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof.

In particular, the optical compensation layer 155 is formed of a material having a refractive index of 1.8 or more and 2.3 or less, and the thickness of the optical compensation layer 155 is formed to a value of 1100 or more and 2500 or less, ) And an effect of improving the luminous efficiency.

The first electrode 160 is formed on the optical compensation layer 155 and may be made of transparent indium tin oxide (ITO) or indium zinc oxide (IZO). However, the first electrode 160 is not limited thereto. The first electrode 160 is electrically connected to the source electrode 133, and a contact hole is formed in a predetermined region of the first passivation layer 140 and the overcoat layer 150. The first electrode 160 may be an anode electrode.

The bank layer 170 is formed on the first electrode 160 and may include an organic material such as a benzocyclobutene (BCB) resin, an acrylic resin, or a polyimide resin. The bank layer 170 is spaced apart from the first electrode 160 by a predetermined opening so that the light emitted from the organic light emitting layer 180 can escape.

The organic light emitting layer 180 is formed on the bank layer 170 and emits white light. 4, the organic light emitting layer 180 includes a first stack 181 formed on the first electrode 160, a CGL layer 183 formed on the first electrode 160, And a second stack 185 formed on the first electrode 160.

Although the second stack 185 is shown on the first stack 181 in FIG. 4, the first stack 181 may be formed on the second stack 185, although not limited thereto.

The first stack 181 includes a first light emitting layer formed on the first electrode 160 and emitting blue light. In detail, the first stack 181 includes an electron injection layer (EIL), an electron transport layer (ETL), a first emission layer (EML), a hole transport layer ) And a hole injection layer (HIL).

The second stack 185 is formed on the first electrode 160 and includes a second light emitting layer that emits yellow green light. More specifically, an electron injection layer (EIL), an electron transport layer (ETL), a second emission layer (EML), a hole transport layer (HTL), and a hole injection layer Injection Layer: HIL).

The thicknesses of the optical compensation layer 155, the first electrode 160, and the organic light emitting layer 180 are factors for determining the emittance spectrum of the organic light emitting display device. .

[Equation 1]

Where n is the refractive index, d is the distance from the cathode to the light emitting layer, and lambda is the distance from the cathode to the light emitting layer. In this case, the first term refers to the optical compensation layer 155, the second term refers to the first electrode 160 and the third term refers to the organic light emitting layer 180, Indicates a blue peak wavelength.

On the other hand, the distance from the cathode to the light emitting layer can be determined according to the following equation (2).

&Quot; (2) "

Here, m is a positive number, n is a refractive index, d is a distance from a cathode electrode to a light emitting layer, and? Is a blue peak wavelength or a yellow green peak wavelength.

A Charge Generation Layer (CGL) layer is formed between the first stack and the second stack.

When driving voltage is applied to the first electrode 160 and the second electrode 190, electrons passing through the hole transporting layer and the electron transporting layer are transferred to the light emitting layers (first and second light emitting layers) to form excitons, As a result, the light emitting layers (first and second light emitting layers) emit visible light. The light emitted from the first and second light emitting layers emits in the form of white light outside the organic light emitting layer 180.

At this time, the divergent white light passes through the color filter 145 and is emitted to the outside toward the substrate. At this time, the light passing through the red color filter is changed to red, the light passing through the blue color filter is changed to blue, and the light passing through the green color filter is changed to green.

Hereinafter, the characteristics of the light emitted from the organic light emitting layer 180 will be described in detail with reference to FIG.

5 is a graph showing a PL spectrum and an emittance spectrum of an organic light emitting diode display according to the present invention.

As can be seen from FIG. 5, the PL spectrum S1 of the OLED display according to the present invention includes a first peak wavelength P1 and a third peak wavelength P3. Further, the emittance spectrum S2 includes a second peak wavelength P2 and a fourth peak wavelength P4.

In the PL spectrum S1, the first peak wavelength P1 refers to the peak wavelength of the first color emitted by the first emitting layer, and the third peak wavelength P3 refers to the peak wavelength of the second color emitted from the second emitting layer It says.

In the emittance spectrum S2, the second peak wavelength P2 refers to the peak wavelength of the first color and the fourth peak wavelength P4 refers to the peak wavelength of the second color.

Here, the PL spectrum (the same as the emission spectrum) is a spectrum in which light emitted from the light emitting layer is analyzed, and refers to a spectrum having characteristics inherent to the characteristics of the dopant doped in the light emitting layer, that is, properties inherent to the dopant and the doping amount.

The emittance spectrum refers to a spectrum having unique characteristics depending on the optical characteristics (thickness, refractive index, etc.) of the layer constituting the organic light emitting layer and the optical compensation layer. In detail, the emittance spectrum may be measured in consideration of the optical characteristics of the layers and the optical compensation layer of the organic light emitting layer and the optical characteristics of the organic light emitting display.

Here, the optical characteristics of the organic light emitting display device refers to characteristics such as the thickness and the refractive index of the components located on all the paths through which the light emitted from the organic light emitting layer passes. The organic light emitting layer and the optical compensation layer may include an overcoat layer, a color filter layer, a protective layer, a thin film transistor layer, a substrate, a polarizing plate, a sealing layer, and the like, in addition to the organic light emitting layer and the optical compensation layer. have.

Further, the EL spectrum is obtained by analyzing the spectrum of the light finally exiting the organic light emitting display device, and is influenced by the characteristics of the PL spectrum and the emittance spectrum.

By adjusting the thickness of the layer of the organic light emitting layer and the thickness of the optical compensation layer, the emittance spectrum can be changed, thereby changing the second peak wavelength P2 and the fourth peak wavelength P4.

On the other hand, by adjusting the optical characteristics (thickness, refractive index, etc.) of the layer and the optical compensation layer of the organic light emitting layer, the emittance spectrum can be changed, thereby changing the second peak wavelength P2 and the fourth peak wavelength P4 . At this time, the second peak wavelength P2 and the fourth peak wavelength P4 in the emittance spectrum change simultaneously by adjusting the optical characteristics (thickness, refractive index, etc.) of the layer and the optical compensation layer of the organic light emitting layer, You need to adjust.

The first peak wavelength P1 can be shifted in the PL spectrum by controlling the doping amount of the dopant of the first light emitting layer or by changing the dopant material and the doping amount of the dopant of the second light emitting layer can be controlled, The third peak wavelength P3 can be shifted in the PL spectrum.

The organic light emitting display according to the present invention may further include a second organic light emitting diode (OLED) having a peak wavelength of a first color on a photoluminescence (PL) spectrum (S1) determined according to a dopant characteristic of the first and second light emitting layers (Second peak wavelength: P1) of the first color on the emittance spectrum S2 determined according to the optical characteristics of the layer and the optical compensation layer constituting the organic light emitting layer, And the peak wavelength (third peak wavelength: P3) of the second color is positioned on the emittance spectrum (S2) on the photoluminescence (PL) spectrum (S1) (Fourth peak wavelength: P4) of the two colors.

This is because, when the first peak wavelength P1 and the second peak wavelength P2 are made to coincide and the third peak wavelength P3 and the fourth peak wavelength P4 are coincident with each other, the luminance reduction rate of the first- The color change phenomenon becomes larger and the color viewing angle characteristic is lowered as the viewing angle is increased.

Therefore, the first peak wavelength P1 is designed to have a shorter wavelength than the second peak wavelength P2, and the third peak wavelength P3 is designed to have a shorter wavelength or a longer wavelength than the fourth peak wavelength P4, Thereby suppressing the change phenomenon and improving the color viewing angle characteristic.

The difference between the first peak wavelength P1 and the second peak wavelength P2 is 10 nm or less and the difference between the third peak wavelength P3 and the fourth peak wavelength P4 is ± 10 nm or less But the present invention is not limited thereto.

On the other hand, the dopant concentration of the second light emitting layer can be doped to not less than 10% and not more than 25% of the host.

At this time, when the dopant concentration of the second light emitting layer is less than 10% with respect to the host, the third peak wavelength P3 becomes shorter than the fourth peak wavelength P4. In this case, when the EL spectrum is analyzed, the change in luminance of the second color light with increasing viewing angle tends to decrease after a slight increase. On the other hand, since the luminance change of the first color light continuously decreases with the increase of the viewing angle, it is difficult to improve the color viewing angle due to a large difference in luminance between the first color light and the second color light.

When the dopant concentration of the second light emitting layer exceeds 25% with respect to the host, the third peak wavelength P3 becomes longer than the fourth peak wavelength P4, so that the color viewing angle characteristic is improved, but the intensity of the second color light decreases . In this case, even if the intensity of the red light is slightly increased, the intensity of the second color light is decreased, and the luminous efficiency of the entire panel is reduced and the power consumption is increased.

On the other hand, the dopant material of the second light emitting layer can be selected so that the third peak wavelength (P3) in the PL spectrum has a wavelength of 540 nm or more and 575 nm or less.

That is, in order to allow the second emission layer to emit the third peak wavelength P3 shifted to a shorter wavelength or a longer wavelength than the fourth peak wavelength P4 of the emission spectrum of the organic emission layer 180, The dopant concentration may be increased (not less than 10% and not more than 25%) or a relatively long wavelength (not less than 540 nm and not more than 575 nm) dopant may be used.

The first color may be blue, and the second color may be yellow and green. However, the present invention is not limited thereto. Hereinafter, the first color is blue and the second color is yellow green.

On the other hand, the color coordinate change amount? U'v 'on the CIE 1931 color coordinate system in the viewing angle direction of 0 ° to 60 ° of the light emitted from the organic light emitting display device is set to 0.02 or less. In this case, between the color coordinate change amount CIE 1931 chromaticity coordinates (u ', v') based on the initial color coordinates _{(u '0, v' 0} ) and the predetermined time t is the color coordinates (u _'t, v' _t) after the last of It is defined as the color coordinate difference.

When the amount of color coordinate change is less than 0.02, the user does not recognize color shift due to the viewing angle.

As described above, when the first peak wavelength P1 is designed to have a shorter wavelength than the second peak wavelength P2 and the third peak wavelength P3 is designed to have a shorter wavelength or a longer wavelength than the fourth peak wavelength P4, , The matching of the PL spectrum and the emittance spectrum is improved, the color shift phenomenon is increased with the increase of the viewing angle, and the color viewing angle characteristic is improved. Further, the luminous efficiency of the red light in the EL spectrum is improved to reduce the voltage, and the luminous efficiency of the panel is improved.

Here, the Voled voltage is a voltage applied to the first electrode (anode electrode) and the second electrode (cathode electrode), and refers to a voltage applied to the sub-pixel having the highest current density among the RGBW sub-pixels.

The organic light emitting display according to the present invention has a full width at half maximum of the peak wavelength of the second color (the third peak wavelength) on the light emission (PL) spectrum in order to improve the color reproduction rate and improve the luminous efficiency, Is formed to be 80 nm or more. Here, the half width (FWHM) means a wavelength range at an amplitude corresponding to 1/2 of the peak of the spectrum.

In one embodiment, the second color may be yellow-green (YG). Since the spectrum of the yellow-green is used to implement the RGB channels including red and green, the half-width of the second color peak wavelength increases, and the luminous efficiency of the red and green channels increases. In addition, the color reproduction rate can be improved by this.

In one embodiment, the half width of the peak wavelength of the second color may be 80 nm or more. In addition, since the emission efficiency of the red and green channels can be largely varied depending on the value of the peak wavelength even if they have the same half width, the peak wavelength can be formed to a value of 540 nm or more and 575 nm or less ).

As described above, in order to realize a spectrum having a half width broadened at the peak wavelength of the second color, a method of using a dopant having a wide half-width, a method of controlling a doping ratio, and a method using a multi- .

Referring again to FIG. 3, the second electrode 190 is formed on the organic light emitting layer 180 and may be formed of a metal material such as aluminum (Al), calcium (Ca), magnesium (Mg) Tin Oxide) or IZO (Indium Zinc Oxide) may be used. At this time, the second electrode 190 may be a cathode electrode.

Hereinafter, results of an experimental example of the organic light emitting diode display according to the present invention will be described in detail.

<Experimental Example 1>

6 is a graph illustrating characteristics of the organic light emitting display according to the present invention in which the optical compensation layer having a thickness of 1600 A is formed after increasing the doping amount of the sulfur-green dopant to 14% and 20%.

As shown in FIG. 6, the thickness of the optical compensation layer was 1600 ANGSTROM, and the thickness of HTL1 / HL3 / ETL2 was 1250, 350, and 450 ANGSTROM. The doping amount of the sulfur-green dopant was 14% and 20% relative to the host.

When the doping amount of the sulfur green dopant is 20% relative to the host, the panel efficiency is increased, the Voled value is decreased, and the color coordinate variation is decreased compared with 14% doping.

FIG. 7 is a graph showing the amount of color coordinate change according to the viewing angle in Experimental Example 1 of FIG.

As shown in FIG. 7, the doping amount of the sulfur-green dopant was doped to 20% of the host, and the amount of change of the color coordinates was analyzed three times to show L11, L12 and L13. The doping amount of the sulfur- %, And the amount of change in color coordinates was analyzed three times to express L11, L12, and L13.

When the doping amount of the sulfur green dopant is 20% relative to the host, it is understood that the chromaticity coordinate variation is decreased and the color viewing angle characteristic is improved as compared with the case where the doping amount is 14%.

8 is a graph showing an EL spectrum according to the doping amount in Experimental Example 1 of FIG.

Doping such that the doping amount of the sulfur green dopant is increased by 20% and 14% with respect to the host, the EL spectrum moves toward the longer wavelength, the luminous efficiency of the red light is improved, the Voled voltage is decreased, and the luminous efficiency of the panel is improved.

<Experimental Example 2>

FIG. 9 is a graph illustrating the characteristics of the organic light emitting diode display according to the present invention in which an optical compensation layer having a thickness of 2200 A is formed, after increasing the doping amount of the sulfur-green dopant to 14% and 20%.

As shown in FIG. 9, the thickness of the optical compensation layer was formed to be 2200 ANGSTROM, and the thickness of HTL1 / HL3 / ETL2 was formed to be 600, 450, and 450 ANGSTROM. The doping amount of the sulfur-green dopant was 20% (a) and 14% (b) relative to the host.

The panel efficiency was increased, the Voled value was decreased, and the amount of change in the chromaticity coordinates was decreased when doping such that the doping amount of the sulfur green dopant was 20% (a) with respect to the host was 14% (b) Able to know.

FIG. 10 is a graph showing the amount of color coordinate change according to the viewing angle in Experimental Example 2 of FIG.

As can be seen from FIG. 10, when the doping amount of the sulfur-doped green dopant is 20% (a) relative to the host, the amount of color coordinate change is decreased and the color viewing angle characteristics are improved have.

11 is a graph showing an EL spectrum according to doping amount in Experimental Example 2 of FIG.

11, when the doping amount of the sulfur-green dopant is increased to 20% (a) and 14% (b) relative to the host, the peak wavelength of the broad green wavelength in the EL spectrum shifts toward the longer wavelength, Since the spectrum is changed, the luminous efficiency of the red light is improved, the Voled voltage is reduced, and the luminous efficiency of the panel is improved.

<Experimental Example 3>

FIG. 12 is a graph illustrating the characteristics of the organic light emitting diode display according to the present invention in which the optical compensation layer is not formed after increasing the doping amount of the sulfur-doped green dopant to 14% and 20%.

As shown in FIG. 12, the doping amount of the sulfur-green dopant was 14% and 20% relative to the host without forming the optical compensation layer.

The panel efficiency was slightly increased, the Voled value was decreased, and the amount of color coordinate change was decreased when the doping amount of the sulfur green dopant was 20% relative to that of the host when the doping amount was 14%.

13 is a graph showing the amount of color coordinate change according to the viewing angle in Experimental Example 3 of FIG.

As can be seen from FIG. 13, when the doping amount of the sulfur green dopant is 20% relative to the host, it is understood that the color coordinate variation is decreased and the color viewing angle characteristics are improved as compared with the case of doping with 14%.

14 is a graph showing an EL spectrum according to the doping amount in Experimental Example 3 of FIG.

As can be seen from Fig. 14, when the doping amount of the sulfur-green dopant is increased to 20% and 14% relative to the host, the peak wavelength of the green wavelength shifts to the longer wavelength in the EL spectrum and consequently changes the EL spectrum The luminous efficiency of the red light is improved, the Voled voltage is reduced, and the luminous efficiency of the panel is thereby improved.

<Experimental Example 4>

FIG. 15 is a diagram showing the intensity variation amount according to the half width variation on the PL spectrum. FIG. In Fig. 15, the horizontal axis indicates wavelength (nm) and the vertical axis indicates luminance (intensity, a.u).

As can be seen from FIG. 15, the region corresponding to the YG peak in the PL spectrum (Broad YG) having the extended half width exhibits a higher luminance in the red and green regions than the PL spectrum (Narrow YG) having the narrow half width.

FIG. 16 is a chart for analyzing the luminance and current density per unit area of the spectra shown in FIG. 15 on an RGB channel.

As can be seen from FIG. 16, the luminous efficiency (cd / A) of the red (R) channel is the same, the current density (mA / cm 2) ) Emission efficiency (cd / A) of the channel was increased and the current density (mA / cm 2) was decreased. In addition, in the overall panel efficiency, the luminous efficiency (cd / A) was increased from 28.97 to 31.10, and the color reproduction ratio was improved from 115 to 119.8.

FIG. 17 is a diagram showing the amount of intensity variation according to the change of the YG peak wavelength. FIG. In Fig. 17, the horizontal axis indicates wavelength (nm) and the vertical axis indicates luminance (intensity, a.u).

As can be seen from FIG. 17, the spectral shape is changed as the wavelength of the YG peak changes in the PL spectrum (Broad YG) having the extended half width, and thus the efficiency of the entire panel is changed.

FIG. 18 is a chart for analyzing the efficiency and the current density according to the change in the peak luminance of each of the R, G, and B channels after transmission of the color filter (CF) of the spectrum shown in FIG.

As can be seen from FIG. 18, the luminous efficiency (cd / A) of the red (R) channel in the PL spectrum (Broad YG) with the extended half width is the highest at 8.94 and the luminous efficiency cd / A) is highest at 35.61 at 540 nm. The current density (mA / cm 2) of the red (R) channel is 53.6 at 540 nm, and the current density (mA / cm 2) of the green (G) channel is 34.8 at the highest at 575 nm.

However, in the overall panel efficiency, the luminous efficiency (cd / A) of the spectrum having the YG peak wavelength of 564 nm is the most excellent at 31.10 and the color reproducibility is the best at 119.8.

It will be understood by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and from the equivalent concept are to be construed as being included in the scope of the present invention .

100 - organic light emitting diode display 110 - substrate
TFT - Thin film transistor 115 - Gate electrode
120 - gate insulating layer 131 - semiconductor layer
133 - source electrode 135 - drain electrode
140 - First protective layer 145 - Color filter
150 - Overcoat layer 155 - Optical compensation layer
160 - first electrode 170 - bank layer
180 organic light emitting layer 190 second electrode

Claims (11)

Board;
A thin film transistor formed on the substrate;
A first electrode formed on the thin film transistor;
A second stack including a first stack including a first light emitting layer formed on the first electrode and emitting a first color, a second light emitting layer formed on the first electrode and emitting a second color, An organic light emitting layer including a CGL (Charge Generation Layer) layer formed between the first stack and the second stack; And
And a second electrode formed on the organic light emitting layer,
The peak wavelength (first peak wavelength) of the first color on the photoluminescence (PL) spectrum determined according to the dopant characteristics of the first and second light emitting layers is determined according to the optical characteristics of the organic light emitting device Is located in a shorter wavelength region than the peak wavelength of the first color (second peak wavelength) on the emittance spectrum,
The dopant concentration of the second light emitting layer is set to 10% or more and 25% or less of the host (Host), or the second light emitting layer emits a wavelength of 540 nm or more and 575 nm or less, And a peak wavelength (third peak wavelength) of the second color on the photoluminescence (PL) spectrum is larger than a peak wavelength (second peak wavelength) of the second color on the emittance spectrum 4 &lt; / RTI &gt; peak wavelength). &Lt; / RTI &gt; The method according to claim 1,
The difference between the peak wavelength of the first color (the first peak wavelength) on the photoluminescence (PL) spectrum and the peak wavelength of the first color on the emittance spectrum (the second peak wavelength) Or less,
The difference between the peak wavelength (the third peak wavelength) of the second color on the photoluminescence (PL) spectrum and the peak wavelength (the fourth peak wavelength) of the second color on the emittance spectrum is ± Lt; RTI ID = 0.0 &gt; nm. &Lt; / RTI &gt; The method according to claim 1,
Wherein the first color is blue, and the second color is yellow and green. delete delete The method according to claim 1,
Wherein the color coordinate change amount (DELTA u'v ') on the CIE 1931 color coordinate system in the viewing angle direction of 0 DEG to 60 DEG of the light emitted from the OLED display device is 0.02 or less. The method according to claim 1,
And an overcoat layer and an optical compensation layer between the thin film transistor and the first electrode. 8. The method of claim 7,
Wherein the refractive index of the optical compensation layer is 1.8 or more and 2.3 or less. 8. The method of claim 7,
Wherein the thickness of the optical compensation layer is greater than or equal to 1100 and less than or equal to 2500. The method according to claim 1,
Wherein the half width (Full Width at Half Maximum) of the peak wavelength of the second color (the third peak wavelength) on the light emission (PL) spectrum is 80 nm or more. 11. The method of claim 10,
And the peak wavelength of the peak wavelength of the second color (the third peak wavelength) on the light emission (PL) spectrum is 540 nm or more and 575 nm or less.

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