WO2016111534A1 - Tandem type organic light emitting device - Google Patents

Abstract

The present invention relates to a tandem type organic light emitting device and, more specifically, to a tandem type organic light emitting device which exhibits low operation voltage, high power efficiency and an excellent color rendering index (CRI). To this end, the present invention provides a tandem type organic light emitting device, the device comprising: a base substrate; a first electrode formed on the base substrate; a second electrode formed to oppose the first electrode; and first to third organic light emitting layers formed in sequence from the first electrode, between the first electrode and the second electrode. The first organic light emitting layer comprises a first light emitting layer for emitting blue light, the second organic light emitting layer comprises a second light emitting layer for emitting yellow light, and the third organic light emitting layer comprises a third light emitting layer for emitting red light.

Description

Tandem organic light emitting device

The present invention relates to a tandem organic light emitting device, and more particularly, to a tandem organic light emitting device having low operating voltage, high power efficiency and excellent color rendering index (CRI).

Recently, displays and lighting devices are required to be lighter, thinner, more efficient, and more environmentally friendly. In order to revive these demands, researches using organic light emitting devices have been conducted.

The organic light emitting device is classified into a single type consisting of one organic light emitting layer and a tandem type in which two or more organic light emitting layers are stacked in series according to a method of forming an organic light emitting layer. Among these, tandem organic light emitting diodes have advantages of high stability and long life compared to single organic light emitting diodes, and thus may be used in display devices or lighting devices requiring high brightness and long lifespan.

On the other hand, the white organic light emitting device has a different organic light emitting layer for emitting light of a plurality of colors between the anode and the cathode. In this case, a charge generation layer is formed between each organic emission layer. In this case, in order to improve device characteristics such as power efficiency and color rendering index (CRI) of the organic light emitting device without adding a component having a separate function, it is necessary to optimize the arrangement order between the organic light emitting layers and the distance between the anode or cathode and the organic light emitting layer. There is.

[Preceding technical literature]

Japanese Patent Publication No. 4649676 (2010.12.24.)

The present invention has been made to solve the problems of the prior art as described above, the object of the present invention is to provide a tandem organic light emitting device showing a low operating voltage, high power efficiency and excellent color rendering index (CRI).

To this end, the present invention, the base substrate; A first electrode formed on the base substrate; A second electrode formed to face the first electrode; A first to third organic light emitting layer sequentially formed from the first electrode between the first electrode and the second electrode, wherein the first organic light emitting layer includes a first light emitting layer emitting blue light, The second organic light emitting layer includes a second light emitting layer for emitting yellow light, and the third organic light emitting layer includes a third light emitting layer for emitting red light.

Here, the distance between the second light emitting layer and the third light emitting layer may be longer than the distance between the first light emitting layer and the second light emitting layer and the distance between the third light emitting layer and the second electrode.

In this case, the distance between the second light emitting layer and the third light emitting layer may be 100 ~ 300nm.

The distance between the first emission layer and the second emission layer and the distance between the third emission layer and the second electrode may be less than 100 nm.

And when the distance between the first electrode and the second electrode is 500 nm or less, the distance between the first light emitting layer and the second electrode is 292 nm, and the distance between the second light emitting layer and the second electrode is 200 nm. The distance between the third light emitting layer and the second electrode may be 60 nm, and the distance between the first electrode and the first light emitting layer may be 95 nm.

The display device may further include a first charge generation layer formed between the first organic emission layer and the second organic emission layer, and a second charge generation layer formed between the second organic emission layer and the third organic emission layer.

In this case, the electronic device may further include a third charge generation layer formed between the first emission layer and the first electrode.

In addition, a hole layer is formed on one side of each of the first to third light emitting layers, and an electron layer is formed on the other side, and the hole layer is formed in the direction of the first electrode, and the electron layer is in the direction of the second electrode. Can be formed.

The base substrate may be made of a flexible substrate.

In this case, the base substrate may be made of thin glass having a thickness of 1.5 mm or less.

According to the present invention, the arrangement order of the blue light emitting layer, the yellow light emitting layer and the red light emitting layer disposed between the anode electrode and the cathode electrode, the distance between the light emitting layers and the cathode or the light emitting layers and the anode electrode and the distance between the light emitting layers is controlled, By optimizing the arrangement of the light emitting layers, it is possible to lower the operating voltage of the tandem organic light emitting diode, thereby increasing power efficiency and improving the color rendering index (CRI) of the tandem organic light emitting diode.

1 is a schematic cross-sectional view showing the structure of a tandem organic light emitting device according to an embodiment of the present invention.

2 is a graph showing the EL spectrum of the tandem organic light emitting device according to Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 of the present invention.

3 is a graph showing EL spectra of tandem organic light emitting diodes according to Example 3, Comparative Example 6, and Comparative Example 7 of the present invention;

4 is a diagram showing simulated contour plots of normalized radiance intensity, and FIG. 5 is a diagram showing normalized radiance according to an electron layer thickness. Is a diagram conceptually showing electron layer thicknesses in a three stack dendum structure.

7 and 8 are diagrams illustrating power efficiency and EL spectra of manufactured unit devices.

Hereinafter, a tandem organic light emitting diode according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In addition, in describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

As shown in FIG. 1, the tandem organic light emitting device 100 according to the embodiment of the present invention includes a base substrate 110, a first electrode 120, a second electrode 130, and an organic light emitting layer. do.

The base substrate 110 serves as a path for emitting light generated from the organic light emitting layer to the outside. To this end, the base substrate 110 is disposed in front of the organic light emitting layer, that is, a path through which light generated from the organic light emitting layer is emitted to the outside. In addition, the base substrate 110 serves to protect the first electrode 120, the second electrode 130, and the organic light emitting layer from the external environment. To this end, that is, in order to encapsulate the first electrode 120, the second electrode 130, and the organic light emitting layer, the base substrate 110 is formed along a rim thereof, for example, through a sealing material such as epoxy. It is bonded to a rear substrate (not shown) disposed on the second electrode 130 to face the second electrode 130. In this case, a space occupied by the first electrode 120, the second electrode 130, and the organic light emitting layer is formed among the internal spaces defined by the base substrate 110 and the rear substrate (not shown) facing each other and the sealing material formed at the edges thereof. The other inner space may be filled with an inert gas or be formed in a vacuum atmosphere.

On the other hand, a separate external light extraction layer (not shown) is formed on the surface of the base substrate 110 in contact with the outside to improve the efficiency of extracting light emitted from the organic light emitting layer to the outside, or the surface itself forms a lens array shape. Can be. In addition, an internal light extraction layer (not shown) may be formed between the base substrate 110 and the first electrode 120.

The base substrate 110 is a transparent substrate and is not limited as long as it has excellent light transmittance and excellent mechanical properties. For example, a polymer-based material which is an organic film capable of thermosetting or UV curing may be used as the base substrate 110. In addition, the base substrate 110 is a chemically tempered glass of soda lime glass _{(SiO 2 -CaO-Na 2 O} ) or alumino-silicate glass _{(SiO 2 -Al 2 O 3 -Na} 2 O) may be used. Here, when the tandem organic light emitting device 100 according to the embodiment of the present invention is used for lighting, soda-lime glass may be used as the base substrate 110. In addition, a substrate made of metal oxide or metal nitride may be used as the base substrate 110. In addition, in the embodiment of the present invention, a flexible substrate may be used as the base substrate 110. In particular, a thin glass having a thickness of 1.5 mm or less may be used. In this case, the thin glass may be manufactured through a fusion method or a floating method. Meanwhile, a back substrate (not shown) forming encapsulation with the base substrate 110 may be made of the same or different material as that of the base substrate 110.

The first electrode 120 is formed on the base substrate 110. The first electrode 120 is a transparent electrode which serves as an anode of the tandem organic light emitting diode 100 and is organic in a material having a high work function so that hole injection into the organic light emitting layer is easily performed. The light emitted from the light emitting layer may be made of a material that can transmit well. For example, the first electrode 120 may be made of ITO.

The second electrode 130 is formed to face the first electrode 120. Accordingly, a plurality of organic emission layers are positioned between the second electrode 130 and the first electrode 120. The second electrode 130 is a metal electrode serving as a cathode of the tandem organic light emitting device 100, and among the materials reflecting light emitted from the organic light emitting layer to the front, that is, the base substrate 110, The work function may be made of a material having a small work function to facilitate electron injection into the light emitting layer. For example, the second electrode 130 may be formed of a metal thin film such as Al, Al: Li, or Mg: Ag.

At least two organic light emitting layers are formed between the first electrode 120 and the second electrode 130 to form the tandem organic light emitting device 100. The tandem organic light emitting device 100 according to the embodiment of the present invention is formed including three organic light emitting layers. That is, in the tandem organic light emitting device 100 according to the embodiment of the present invention, the first organic light emitting layer 140 is sequentially formed from the first electrode 120 between the first electrode 120 and the second electrode 130. , The second organic light emitting layer 150 and the third organic light emitting layer 160 are formed. In this case, the first organic light emitting layer 140 and the second organic light emitting layer 150 are connected through a first charge generation layer (CGL) 170 formed therebetween, and the second organic light emitting layer 150 ) And the third organic light emitting layer 160 are connected through the second charge generation layer 180 formed therebetween.

In an embodiment of the present invention, the first organic emission layer 140 includes a first emission layer 141 that emits blue light. In this case, the first emission layer 141 may be formed of a material emitting blue light having a wavelength of 450 ± 5 nm. In addition, the second organic emission layer 150 includes a second emission layer 151 emitting yellow light. In this case, the second light emitting layer 151 may be formed of a material emitting yellow light having a wavelength of 540 ± 5 nm. The third organic light emitting layer 160 includes a third light emitting layer 161 emitting red light. In this case, the third emission layer 161 may be formed of a material that emits red light in a wavelength range of 610 ± 5nm. As described above, the tandem organic light according to the embodiment of the present invention is produced by the mixing effect of the blue light, the yellow light, and the red light emitted from the first light emitting layer 141, the second light emitting layer 151, and the third light emitting layer 161, respectively. The light emitting device 100 emits white light.

Here, the tandem organic light emitting device 100 according to the embodiment of the present invention has a blue / yellow / red first to third light emitting layer (1) from the first electrode 120 when viewed from the first electrode 120. 141, 151, and 161 form a structure arranged in sequence. In this embodiment, the distance between the second light emitting layer 151 and the third light emitting layer 161 is the distance between the first light emitting layer 141 and the second light emitting layer 151 and the third light emitting layer 161 and the third light emitting layer 161. It may be formed longer than the distance between the two electrodes (130). For example, the distance between the second light emitting layer 151 and the third light emitting layer 161 may be 100 to 300 nm. In this case, each of the first light emitting layer 141, the second light emitting layer 151, the third light emitting layer 161, and the second electrode 130 may have a distance between them less than 100 nm. Further, in the embodiment of the present invention, the distance between the second electrode 130 and the first light emitting layer 141, the distance between the second electrode 130 and the second light emitting layer 151, the second electrode 130 and the third light emitting layer The distance between the 161 and the distance between the first light emitting layer 141 and the first electrode 120 is controlled to a predetermined range. For example, when the distance between the first electrode 120 and the second electrode 130 is 500 nm or less, the distance between the first light emitting layer 141 and the second electrode 130 is 292 nm and the second light emitting layer 151. ) And the distance between the second electrode 130 is 200 nm, the distance between the third light emitting layer 161 and the second electrode 130 is 60 nm, and the distance between the first electrode 120 and the first light emitting layer 141 is 95 nm. Controlling to nm may be most desirable to improve device performance of the tandem organic light emitting device 100.

As described above, in the exemplary embodiment of the present invention, the first light emitting layer 141 which emits blue light sequentially from the first electrode 120, and emits yellow light between the first electrode 120 and the second electrode 130. The second light emitting layer 151 and the third light emitting layer 161 emitting red light are arranged, and the distance between the light emitting layers 141, 151, 161 and the second electrode 130 is controlled. Through this, in the tandem organic light emitting device 100 according to the embodiment of the present invention, the arrangement of the light emitting layers 141, 151, and 161 is optimized, resulting in low operating voltage, high power efficiency, and excellent color rendering index (CRI). It can be implemented.

Meanwhile, the first organic emission layer 140 includes a hole layer 142 formed on one side of the first emission layer 141 and an electron layer 143 formed on the other side of the first emission layer 141. In addition, the second organic emission layer 150 includes a hole layer 152 formed on one side of the second emission layer 151 and an electron layer 153 formed on the other side of the second emission layer 151. The third organic emission layer 160 includes a hole layer 162 formed on one side of the third emission layer 161 and an electron layer 163 formed on the other side of the third emission layer 161. In this case, the hole layers 142, 152, and 162 are formed in the direction of the first electrode 120, and the electron layers 143, 153, and 163 are formed in the direction of the second electrode 130.

Although not shown in detail, each of the hole layers 142, 152, and 162 may have a stacked structure of a hole injection layer HIL and a hole transport layer HTL, and the hole transport layer HTL may be, for example, a p-type. It may be made of a multilayer structure including a hole transport layer. In addition, the electron layers 143, 153, and 163 may have a stacked structure of an electron injection layer EIL and an electron transport layer ETL, and the electron transport layer ETL may have a multilayer structure including, for example, an n-type electron transport layer. Can be done.

Accordingly, in the case of the first organic emission layer 140, holes move from the first electrode 120 to the first emission layer 141 through the hole layer 142 and electrons from the first charge generation layer 170. Is moved to the first emission layer 141 through the electron layer 143. In this case, a third charge generation layer (not shown) may be formed between the first organic emission layer 140 and the first electrode 120, and between the third charge generation layer (not shown) and the first electrode 120. A hole injection layer HIL (not shown) may be formed therein. In this case, in the first organic emission layer 140, holes are injected from the first electrode 120 through the hole injection layer HIL, the third charge generation layer (not shown), and the hole layer 142. Will be moved to. Also, in the case of the second organic light emitting layer 150, holes move from the first charge generation layer 170 to the second light emitting layer 151 through the hole layer 152, and from the second charge generation layer 180. Electrons move to the second emission layer 151 through the electron layer 153. In the third organic emission layer 160, holes move from the second charge generation layer 180 to the third emission layer 161 through the hole layer 162, and electrons from the second electrode 130 are electrons. The third light emitting layer 163 is moved through the layer 163.

When forward voltage is applied to the first electrode 120 and the second electrode 130, electrons and holes are moved to the respective light emitting layers 141, 151, and 161 through the above path. As such, the electrons and holes injected into the light emitting layers 141, 151, and 161 recombine in the light emitting layers 141, 151, and 161 to generate excitons, and the excitons are in an excited state. The light is emitted while transitioning to the ground state, wherein the brightness of the emitted light flows between the first electrode 120 serving as the anode electrode and the second electrode 130 serving as the cathode electrode. It is proportional to the amount of current.

Example 1

Tandem organic light emitting device consisting of a laminated structure of anode electrode / hole layer / blue light emitting layer / electron layer / charge generating layer / hole layer / yellow light emitting layer / electron layer / charge generating layer / hole layer / red light emitting layer / electron layer / cathode electrode Was produced.

Comparative Example 1

Tandem organic light emitting device consisting of a laminated structure of anode electrode / hole layer / yellow light emitting layer / electron layer / charge generating layer / hole layer / blue light emitting layer / electron layer / charge generating layer / hole layer / red light emitting layer / electron layer / cathode electrode Was produced.

Comparative Example 2

Tandem organic light emitting device consisting of a laminated structure of anode electrode / hole layer / red light emitting layer / electron layer / charge generating layer / hole layer / yellow light emitting layer / electron layer / charge generating layer / hole layer / blue light emitting layer / electron layer / cathode electrode Was produced.

Comparative Example 3

Tandem organic light emitting device consisting of a laminated structure of anode electrode / hole layer / yellow light emitting layer / electron layer / charge generating layer / hole layer / red light emitting layer / electron layer / charge generating layer / hole layer / blue light emitting layer / electron layer / cathode electrode Was produced.

@ 3,000nit Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Operating voltage (V) 10.2 10.9 10.5 12.3 Power efficiency (lm / W) 25.6 14.2 17.5 6.1 CIE (x, y) (0.453, 0.463) (0.424, 0.393) (0.453, 0.463) (0.362, 0.374) CRI 75.4 88.5 41.9 85.9

2 is a graph showing the EL spectrum of the tandem organic light emitting device according to Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 of the present invention. Referring to Table 1 above, which shows the operating voltage, power efficiency, CIE, and CRI of the tandem organic light emitting diode according to Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 showing such an EL spectrum, Example 1 in which the light emitting layer, the yellow light emitting layer, and the red light emitting layer are arranged in sequence shows a slightly lower color rendering index (CRI) than Comparative Example 1 and Comparative Example 3, but the driving voltage is lower than that of Comparative Examples 1, 2, and 3, It was confirmed that the moonlight shows high power efficiency.

Example 2

In the tandem organic light emitting device having the same structure as Example 1, the distance between the blue light emitting layer and the cathode electrode, the distance between the yellow light emitting layer and the cathode electrode, and the distance between the red light emitting layer and the cathode were 292 nm, 200 nm, and 60 nm, respectively. Controlled.

Comparative Example 4

In the tandem organic light emitting diode having the same structure as Example 1, the distance between the blue light emitting layer and the cathode electrode, the distance between the yellow light emitting layer and the cathode electrode, and the distance between the red light emitting layer and the cathode were 312 nm, 220 nm, and 60 nm, respectively. Controlled.

Comparative Example 5

In the tandem organic light emitting device having the same structure as Example 1, the distance between the blue light emitting layer and the cathode electrode, the distance between the yellow light emitting layer and the cathode electrode, and the distance between the red light emitting layer and the cathode were 284 nm, 192 nm, and 60 nm, respectively. Controlled.

@ 3,000nit Example 2 Comparative Example 4 Comparative Example 5 Operating voltage (V) 9.62 10.6 9.84 Power efficiency (lm / W) 44.9 22.7 34.4 CIE (x, y) (0.465, 0.448) (0.508, 0.438) (0.448, 0.455) CRI 80.5 75.5 75.0

Referring to Table 2 showing the operating voltage, power efficiency, CIE, and CRI of the tandem organic light emitting diode according to Example 2, Comparative Example 4 and Comparative Example 5 of the present invention, the distance between the blue light emitting layer and the cathode electrode, and the yellow light emitting layer Example 1, in which the distance between the cathode and the cathode, and the distance between the red light emitting layer and the cathode, were controlled at 292 nm, 200 nm, and 60 nm, respectively, has a lower driving voltage and significantly higher power efficiency than Comparative Example 4 and Comparative Example 5. The color rendering index (CRI) was also found to be relatively good.

Example 3

In the tandem organic light emitting device having the same structure as in Example 2, the distance between the blue light emitting layer and the anode electrode was controlled to 95 nm.

Comparative Example 6

In the tandem organic light emitting device having the same structure as in Example 2, the distance between the blue light emitting layer and the anode electrode was controlled to 65 nm.

Comparative Example 7

In the tandem organic light emitting device having the same structure as in Example 2, the distance between the blue light emitting layer and the anode electrode was controlled to 125 nm.

@ 3,000nit Example 3 Comparative Example 6 Comparative Example 7 Operating voltage (V) 8.34 8.51 8.51 Power efficiency (lm / W) 43.5 44.5 43.8 CIE (x, y) (0.427, 0.450) (0.420, 0.465) (0.436, 0.448) CRI 81.9 79.3 85.8

3 is a graph showing EL spectra of tandem organic light emitting diodes according to Example 3, Comparative Example 6, and Comparative Example 7 of the present invention. Referring to Table 3, which shows the operating voltage, power efficiency, CIE, and CRI of the tandem organic light emitting diode according to Example 3, Comparative Example 6, and Comparative Example 7, which show such an EL spectrum, the distance between the blue light emitting layer and the anode electrode Example 3, which is controlled to 95 nm, has a lower operating voltage than Comparative Example 6 and Comparative Example 7, and it is confirmed that there is no difference in power efficiency and color rendering index (CRI).

In the embodiments 1-3, and Comparative Examples 1-7, the optimal arrangement of the light emitting layers in the tandem organic light emitting device is arranged from the anode electrode to the blue light emitting layer, the yellow light emitting layer and the red light emitting layer in turn, and the blue light emitting layer and the cathode electrode The distance between the yellow light emitting layer and the cathode, the distance between the red light emitting layer and the cathode was 292 nm, 200 nm, 60 nm and the distance between the blue light emitting layer and the anode electrode was 95 nm, respectively.

4 is a diagram illustrating simulated contour plots of normalized radiance intensity, and FIG. 5 is a diagram illustrating normalized radiance according to an electron layer thickness.

Prior to fabricating three-stack tandem devices, phosphorescent red, yellow-green and fluorescent bluebottom emission unit devices before were fabricated. . The radiance distribution of the light emitting layer was simulated by varying the thickness of the electron and hole layers. As a result, it can be seen that the radiance distribution is more sensitive to the thickness of the electronic layer than the thickness of the hole layer.

6 conceptually shows electron layer thicknesses in a three-stack dendum structure.

7 and 8 are diagrams illustrating power efficiency and EL spectra of manufactured unit devices.

Monochromatic OLEDs were produced. Their dimensions are as follows.

Device R (Red): ITO (150 nm) / p-hole layer (82 nm) / hole layer (43 nm) / R-light emitting layer (15 nm) / electron layer (10 nm) / n-electron layer (50 nm ) / Al (100 nm).

Device YG (Yello-Green): ITO (150 nm) / p-hole layer (82 nm) / hole layer (43 nm) / YG- light emitting layer (15 nm) / electron layer (10 nm) / n-electron layer ( 40 nm) / Al (100 nm).

Device B (Blue): ITO (150 nm) / p-hole layer (40 nm) / hole layer (25 nm) / B-light emitting layer (15 nm) / electron layer (10 nm) / n-electron layer (20 nm ) / Al (100 nm).

As shown in FIG. 7, for device R (2.5V), device YG (2.5V) and device B (2.9V), respectively, 40.6 lm / W (22.8%), 109.4 lm / W (24.0%), And 8.7 lm / W (5.1%) of power efficiency. From these results, it is possible to predict the power efficiency of a three-stack tandem white device, provided there is no electrical and optical loss due to the interconnecting of the units. The calculated Power Efficiency (PE) and External Quantum Efficiency (EQE) of the 3-stack white device are 55 lm / W and 52% at luminance 1000 nit (7.5V).

As shown in Fig. 8, the normalized unit spectra can be superimposed to calculate the EL spectrum of the tandem device.

As described above, although the present invention has been described with reference to the limited embodiments and the drawings, the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

[Description of the code]

100: tandem organic light emitting device 110: base substrate

120: first electrode 130: second electrode

140: first organic light emitting layer 141: first light emitting layer

150: second organic light emitting layer 151: second light emitting layer

160: third organic light emitting layer 161: third light emitting layer

170: first charge generation layer 180: second charge generation layer

142, 152, 162: hole layer 143, 153, 163: electron layer

Claims (10)

A base substrate; A first electrode formed on the base substrate; A second electrode formed to face the first electrode; Including the first to third organic light emitting layer which is sequentially formed from the first electrode between the first electrode and the second electrode, The first organic emission layer includes a first emission layer emitting blue light, the second organic emission layer includes a second emission layer emitting yellow light, and the third organic emission layer is a third emission layer emitting red light Tandem organic light emitting device comprising a. The method of claim 1, And a distance between the second light emitting layer and the third light emitting layer is longer than the distance between the first light emitting layer and the second light emitting layer and the distance between the third light emitting layer and the second electrode. The method of claim 2, Tandem organic light emitting device, characterized in that the distance between the second light emitting layer and the third light emitting layer is 100 ~ 300nm. The method of claim 3, The distance between the first light emitting layer and the second light emitting layer and the distance between the third light emitting layer and the second electrode is less than 100nm, tandem organic light emitting device. The method of claim 1, When the distance between the first electrode and the second electrode is 500 nm or less, the distance between the first light emitting layer and the second electrode is 292 nm, the distance between the second light emitting layer and the second electrode is 200 nm, 3, the distance between the light emitting layer and the second electrode is 60nm, the distance between the first electrode and the first light emitting layer is 95nm, tandem organic light emitting device. The method of claim 1, And a first charge generating layer formed between the first organic light emitting layer and the second organic light emitting layer, and a second charge generating layer formed between the second organic light emitting layer and the third organic light emitting layer. Organic light emitting device. The method of claim 6, And a third charge generating layer formed between the first organic light emitting layer and the first electrode. The method of claim 1, A hole layer is formed on one side of each of the first to third light emitting layers, and an electron layer is formed on the other side. And the hole layer is formed in the direction of the first electrode, and the electron layer is formed in the direction of the second electrode. The method of claim 1, The base substrate is a tandem organic light emitting device, characterized in that consisting of a flexible substrate. The method of claim 9, The base substrate is a tandem organic light emitting device, characterized in that made of thin glass with a thickness of 1.5mm or less.

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