KR20160094553A - Organic Light Emitting Diode and Organic Light Emitting Diode Display Device, and Method for Fabricating the Same - Google Patents

Abstract

An organic electroluminescent device and an organic electroluminescent display device using the same, and a manufacturing method thereof are disclosed. The organic electroluminescent device comprises: a hole injection layer disposed on a first electrode disposed on a red subpixel region, a green subpixel region, and a blue subpixel region; a hole transport layer on the hole injection layer; and red and green light emitting layers disposed on the hole transport layer, and disposed on the red and green subpixel regions, respectively. The organic electroluminescent device further comprises: a buffer layer on the hole transport layer in the red and green light emitting layers and the blue subpixel region; a blue light emitting layer on the buffer layer; an electron transport layer on the blue light emitting layer; an electron injection layer on the electron transport layer; and a second electrode on the electron injection layer.

Description

[0001] The present invention relates to an organic electroluminescent device, an organic electroluminescent display device using the same, and a method of manufacturing the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device and an organic electroluminescent device using the same and a method of manufacturing the same. More particularly, the present invention relates to an organic electroluminescent device capable of improving driving voltage, lifetime, current characteristics, And a method of manufacturing the same.

In recent years, as the information age has come to a full-fledged information age, a display field for visually representing electrical information signals has been rapidly developed. In response to this, various flat panel display devices having excellent performance of thinning, lightweighting, Flat Display Device) has been developed to replace CRT (Cathode Ray Tube).

Specific examples of such flat panel display devices include a liquid crystal display device (LCD), an organic light emitting display (OLED), an electrophoretic display (EPD) A plasma display panel (PDP), a field emission display (FED), an electroluminescence display (ELD), and an electro-wetting display (EWD) And the like. In general, a flat panel display panel, which realizes images, is an essential component. The flat panel display panel includes a pair of substrates bonded together with an intrinsic light emitting material or a polarizing material layer therebetween.

The organic light emitting diode (OLED) display device, which is one of such flat panel display devices, is a self-luminous device and can be lightweight and thin because a separate light source used in a liquid crystal display device, which is a non-light emitting device, is not required. In addition, it has superior viewing angle and contrast ratio compared with liquid crystal display devices, is advantageous in terms of power consumption, can be driven by DC low voltage, has a quick response speed, is resistant to external impacts due to its solid internal components, It has advantages.

In order to fabricate such an organic light emitting display device in a large area, a hole injection layer, a hole transporting layer, a red light emitting layer and a green light emitting layer of an organic electroluminescent device are formed through a solution process using a liquid organic light emitting material, The electron transporting layer and the electron injecting layer are formed by vacuum deposition.

At this time, due to the morphology difference between the layer formed by the solution process and the layer formed by the vacuum deposition method, a charge accumulation phenomenon occurs. Therefore, the charge balance is lowered at the interface between the red and green light-emitting layers and the blue light-emitting layer, thereby deteriorating the life of the device and deteriorating the color purity.

It is an object of the present invention to provide an organic electroluminescent device that improves driving voltage, lifetime, current characteristics, and color coordinates of a device, an organic light emitting display having the same, and a method of manufacturing the same.

According to an aspect of the present invention, there is provided an organic electroluminescent display device, an organic electroluminescent display device including the organic electroluminescent display device, and a method of manufacturing the same. The organic electroluminescent display device includes a red sub pixel region, a green sub pixel region, Emitting layer disposed on the red and green sub-pixel regions, the red and green sub-pixel regions being disposed on the hole transport layer and the hole transport layer on the hole injection layer and including a first electrode and a hole injection layer on the first electrode, do. And a buffer layer on the hole transport layer in the red and green light emitting layers and the blue sub pixel region, a blue light emitting layer on the buffer layer, an electron transport layer on the blue light emitting layer, an electron injection layer on the electron transport layer and a second electrode on the electron injection layer .

Here, the hole injection layer, the hole transport layer, the red emission layer, the green emission layer, and the buffer layer may be formed by a solution process, and the blue emission layer, the electron transport layer, and the electron injection layer may be formed by vacuum deposition. That is, the buffer layer may be disposed on the red light emitting layer formed by the solution process in the red sub pixel region and the green sub pixel region, and on the second hole transport layer formed by the solution process in the green light emitting layer and the blue sub pixel region.

The buffer layer according to the first embodiment of the present invention may be composed of a compound represented by the following formula (1).

In Formula 1, n is an integer of 1 to 100, and R is -H, -OCH _3, or -OCH ₂ CH ₃ .

In addition, the buffer layer according to the second embodiment of the present invention may be composed of a first layer, a second layer below the first layer, and a third layer below the second layer. In this case, the first layer of the buffer layer may be represented by Formula 1, and R may be -OCH ₂ CH ₃ , -OCH ₃ , -H, respectively.

In addition, the first layer of the buffer layer may be composed of the compound represented by Formula 1, the second layer may be composed of the compound represented by Formula 2, and the third layer may be composed of the compound represented by Formula 3 below.

In Formula 2, k, l and m are each an integer of 1 to 1000, and Formula 2 includes at least one substituted or unsubstituted oxide, oxetane, amine group, phosphine, phenyl group or halogen group.

In Formula 3, R ₁ , R ₂ , R _3, and R ₄ are each independently selected from an alkyl group or an alkenyl group having 1 to 1000 carbon atoms including substituents of a hydroxyl group, a phenyl group, or a halogen group.

The organic electroluminescent device, the organic electroluminescent display device having the same, and the method of manufacturing the same according to the present invention are characterized in that a buffer layer is disposed between red, green and blue hole-transport layers formed by a solution process and a blue light- And the interface characteristics between the hole transporting layer and the blue light emitting layer can be improved. Further, the organic electroluminescent device according to the present invention, the organic electroluminescent display device having the same, and the manufacturing method thereof can improve the driving voltage, lifetime, current characteristic, and color coordinate of the organic electroluminescent device.

1 is a schematic view illustrating an organic electroluminescent device according to a first embodiment of the present invention.
2 is a diagram illustrating a portion of an organic light emitting display according to a second embodiment of the present invention.
3 is a cross-sectional view of a red sub-pixel region in the organic light emitting display according to the present invention.
4 is a cross-sectional view of a blue sub-pixel region in an organic light emitting display according to the present invention.
FIGS. 5A to 5D are graphs comparing device characteristics according to Experimental Examples and Comparative Examples of the present invention when a red light emitting layer is used.
6A to 6D are graphs comparing device characteristics according to Experimental Examples and Comparative Examples of the present invention when a green light emitting layer is used.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

In the case where the word 'includes', 'having', 'done', etc. are used in this specification, other parts can be added unless '~ only' is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

In the case of a description of a temporal relationship, for example, if a temporal posterior relationship is described by 'after', 'after', 'after', 'before', etc., 'May not be contiguous unless it is used.

The first, second, etc. are used to describe various components, but these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

1 is a schematic view showing a part of an organic light emitting display according to a first embodiment of the present invention. 1, an organic light emitting display according to a first embodiment of the present invention includes a substrate 100 divided into a red sub pixel region R, a green sub pixel region G and a blue sub pixel region B, ) Of the organic electroluminescent device. The organic electroluminescent device includes a first electrode 111, an organic light emitting layer 200, and a second electrode 120.

The first electrode 111 of the organic electroluminescent device may be an anode electrode. Here, although the first electrode 111 is shown as a single layer in the drawing, the first electrode 111 is not limited to this, but may be composed of multiple layers.

A hole injection layer 201 (HIL) of the organic light emitting layer 200 is disposed on the first electrode 111. A hole transport layer 202 is disposed on the hole injection layer 201.

Specifically, the first hole transporting layer 202a is disposed on the red sub pixel region R and the green sub pixel region G, and the second hole transport layer 202b is disposed on the blue sub pixel region B . Thus, hole transport in the organic electroluminescent device can be facilitated. However, the organic electroluminescent device is not limited thereto, and the hole injection layer 201 may be omitted.

A red light emitting layer 203a and a green light emitting layer 203b are disposed on the first hole transporting layer 202a. In detail, a red light emitting layer 203a is disposed on the first hole transporting layer 202a disposed in the red sub pixel region R. A green light emitting layer 203b is disposed on the first hole transporting layer 202a disposed in the green sub pixel region G. [

In order to realize a large area organic electroluminescence display, a hole injection layer, a hole transport layer, a red light emitting layer and a green light emitting layer of an organic electroluminescent device are formed through a solution process using a liquid organic light emitting material, and a blue light emitting layer, And the electron injection layer are formed by vacuum deposition.

At this time, in the red and green sub pixel regions, a charge accumulation phenomenon occurs due to the morphology difference between the red and green emission layers formed by the solution process and the blue emission layer formed by the vacuum deposition method. Therefore, the charge balance is lowered at the interface between the red and green light emitting layers and the blue light emitting layer, so that the lifetime of the device is lowered and the color is not clearly displayed.

In the blue sub pixel region, the charge accumulation phenomenon occurs due to the difference in the interface type between the hole transport layer formed by the solution process and the blue light emitting layer formed by the vacuum evaporation method. Therefore, the charge balance is lowered at the interface between the hole transporting layer and the blue light emitting layer, so that the lifetime of the device is lowered and the color is not clearly displayed.

The organic electroluminescent device according to the present invention includes a red light emitting layer 203a and a green light emitting layer 203b formed in a solution process in a red sub pixel region R and a green sub pixel region G, and a buffer layer 210 disposed on the second hole transporting layer 202b formed by the solution process in FIG. At this time, since the transmission injection layer 201, the hole transport layer 202, the red light emitting layer 203a, and the green light emitting layer 203b are formed by the solution process, it is easy to manufacture a large area organic light emitting display device.

The blue light emitting layer 203c, the electron transport layer 204, and the electron injection layer 205, which are sequentially formed on the buffer layer 210, may be formed by a vacuum deposition method. Thus, the characteristics of the device can be improved.

The buffer layer 210 may be formed by a solution process on the red light emitting layer 203a, the green light emitting layer 203b, and the second hole transporting layer 202b. At this time, the buffer layer may be composed of a compound represented by the following general formula (1).

[Chemical Formula 1]

In Formula 1, n may be an integer of 1 to 100. And, R can be -H, -OCH ₃ or -OCH ₂ CH _3.

A blue light emitting layer 203c is disposed on the buffer layer 210 of Formula 1. The blue light emitting layer 203c may be disposed in the red, green, and blue sub-pixel regions R, G, and B. The lower part of the buffer layer 210 is cross-linked with the red and green light emitting layers 203a and 203b and the second hole transporting layer 202b and the upper part of the buffer layer 210 is connected to the blue light emitting layer 203c ).

The gap between the molecular chains of the buffer layer 210 and the molecular chains of the red, green light emitting layers 203a and 203b and the second hole transporting layer 202b may be denser at the lower portion of the buffer layer 210. [ In addition, the distance between the molecular chain of the buffer layer 210 and the molecular chain of the blue light-emitting layer 203c may be increased at the upper portion of the buffer layer 210.

That is, the buffer layer 210 is disposed on the red light emitting layer 203a, the green light emitting layer 203b, and the second hole transporting layer 202b formed by a solution process, so that the blue light emitting layer 203b formed by the vacuum evaporation method, The interfacial characteristics between the first electrode 210 and the second electrode 210 can be improved. In detail, the upper surface of the buffer layer 210 contacting the blue light emitting layer 203b is made flat, so that the interface characteristics between the buffer layer 210 and the blue light emitting layer 203b can be improved.

Here, since the buffer layer 210 is made of a bulk polymer as shown in Formula 1, the packing factor of the buffer layer 210 is increased. Accordingly, the buffer layer 210 may be disposed on the substrate 100 in a flat shape.

The thickness of the buffer layer 210 may be 1 nm to 100 nm. At this time, if the thickness of the buffer layer 210 is less than 1 nm, it may be difficult to form the buffer layer 210. If the thickness of the buffer layer 210 exceeds 100 nm, the charge balance of the organic electroluminescent device may be degraded.

In addition, the buffer layer 210 is not limited thereto, and the buffer layer 210 may further include a photoinitiator. Accordingly, the material of the buffer layer 210 facilitates ring opening polymerization, so that the buffer layer 210 may have a conjugation structure. Therefore, the mobility of the buffer layer 210 can be improved by increasing the number of? -Electrons in the buffer layer 210.

The photoinitiator may be contained in 30% or less of each layer. If the photoinitiator is contained in an amount exceeding 30%, the lifetime of the organic electroluminescent device may be reduced.

An electron transporting layer 204 is disposed on the blue light emitting layer 203b. An electron injection layer 205 may be disposed on the electron transport layer 204. A second electrode 120 of the organic electroluminescent device is disposed on the electron injection layer 205. Here, the second electrode 120 may be a cathode electrode.

The organic EL device according to the first embodiment of the present invention includes a buffer layer 210 on a red light emitting layer 203a, a green light emitting layer 203b and a second hole transporting layer 202b formed by a solution process, The interface characteristics between the blue light emitting layer 203b and the buffer layer 210 can be improved. Accordingly, the lifetime and color purity of the organic electroluminescent device can be improved.

Next, referring to FIG. 2, a part of an organic light emitting display according to a second embodiment of the present invention will be described. 2 is a diagram illustrating a portion of an organic light emitting display according to a second embodiment of the present invention. The organic light emitting display device according to the second embodiment may include the same components as those of the previously described embodiments. The description overlapping with the embodiment described above can be omitted. The same components have the same reference numerals.

2, an organic light emitting display according to a second exemplary embodiment of the present invention includes an organic electroluminescent device including a first electrode 111, an organic light emitting layer 250, and a second electrode 120 . The organic electroluminescent device includes a first electrode 111, an organic emission layer 250, and a second electrode 120.

In detail, a hole injection layer 201 is disposed on the first electrode 111, and a hole transport layer 202 is disposed on the hole injection layer 201. The hole transport layer 202 is divided into a first hole transport layer 202a disposed on the red and green sub pixel regions R and G and a second hole transport layer 202b disposed on the blue sub pixel region B. do.

Red and green light emitting layers 203a and 203b are disposed on the first hole transporting layer 202a disposed in the red and green sub pixel regions R and G, respectively. A buffer layer 210 is disposed on the red and green light emitting layers 203a and 203b and the second hole transporting layer 202b.

The buffer layer 211 may be formed of a triple layer. In detail, the buffer layer 211 includes a first layer 211a, a second layer 211b disposed under the first layer 211a, and a third layer 211c disposed below the second layer 211b. ). That is, the first layer 211a of the buffer layer 211 is disposed in contact with the lower portion of the blue light emitting layer 203c, and the third layer 211c of the buffer layer 211 includes red and green light emitting layers 203a and 203b, And may be disposed in contact with the top of the second hole transport layer 202b.

The buffer layer 211 may be formed by a solution process on the red light emitting layer 203a, the green light emitting layer 203b, and the second hole transporting layer 202b. In detail, the first to third layers 211a, 211b and 211c of the buffer layer 211 may be formed by a solution process. In this case, the first to third layers 211a, 211b and 211c of the buffer layer 211 may be made of a compound represented by the following Chemical Formula 1.

[Chemical Formula 1]

In Formula 1, n may be an integer of 1 to 100. And, in the first layer (211a) R may be -OCH ₂ CH _3. In the second layer (211b) R may be -OCH _3. In the third layer 211c, R may be -H.

On the first layer 211a of the buffer layer 211, a blue light emitting layer 203c is disposed. At this time, the buffer layer 211 may be made bulky so as to be adjacent to the blue light emitting layer 203c. That is, as the buffer layer 211 becomes closer to the blue light emitting layer 203c, the filling rate becomes higher, so that the buffer layer 210 can be arranged on the substrate 100 in a flat shape. Thus, the interface characteristics between the buffer layer 210 and the blue light emitting layer 203c can be improved.

The materials of the first to third layers 211a, 211b, and 211c of the buffer layer 211 are not limited thereto and may be variously formed. For example, the first layer 211a of the buffer layer 211 may be formed of a compound represented by Formula 1 below.

[Chemical Formula 1]

In Formula 1, n may be an integer of 1 to 100. And, R can be -H, -OCH ₃ or -OCH ₂ CH _3.

The second layer 211b of the buffer layer 211 may be formed of a compound represented by Formula 2 below.

(2)

In Formula 2, k, l and m are each an integer of 1 to 1000, and Formula 2 includes at least one substituted or unsubstituted oxide, oxetane, amine group, phosphine, phenyl group or halogen group.

The third layer 211c of the buffer layer 211 may be formed of a compound represented by the following Chemical Formula 3.

(3)

In Formula 3, R ₁ , R ₂ , R _3, and R ₄ are each independently selected from an alkyl group or an alkenyl group having 1 to 1000 carbon atoms including substituents of a hydroxyl group, a phenyl group, or a halogen group.

That is, the second layer 211b of the buffer layer 211 is made of a material that is bulkier than the first layer 211a, and the third layer 211c is made of a material that is bulkier than the second layer 211b Lt; / RTI > That is, the filling rate of the buffer layer 211 can be sequentially improved. Accordingly, the buffer layer 211 is formed flat, so that the interface characteristics between the buffer layer 211 and the blue light emitting layer 203c can be improved.

The thicknesses of the first to third layers 211a, 211b, and 211c of the buffer layer 211 may be 1 nm to 100 nm, respectively. If the thicknesses of the first to third layers 211a, 211b, and 211c are less than 1 nm, it may be difficult to form the buffer layer 211. In addition, when the thickness of the first to third layers 211a, 211b, and 211c exceeds 100 nm, the charge balance of the organic electroluminescent device may be degraded.

In addition, the buffer layer 211 is not limited thereto, and the first to third layers 211a, 211b, and 211c of the buffer layer 211 may further include a photoinitiator. An electron transporting layer 204 is disposed on the blue light emitting layer 203c. An electron injection layer 205 and a second electrode 120 are sequentially disposed on the electron transport layer 204.

The organic electroluminescent device of the organic electroluminescent display device according to the second embodiment of the present invention is characterized in that a filling rate is sequentially applied on the red light emitting layer 203a, the green light emitting layer 203b and the second hole transporting layer 202b formed by the solution process The interfacial characteristics between the blue light emitting layer 203b and the buffer layer 210 can be improved. Accordingly, the lifetime and color purity of the organic electroluminescent device can be improved.

3, a cross-sectional view of a red sub-pixel region in an organic light emitting display according to the present invention will be described. 3 is a cross-sectional view of a red sub-pixel region in the organic light emitting display according to the present invention. The organic light emitting display device according to the present invention may include the same components as those of the above-described embodiments. The description overlapping with the embodiments described above may be omitted. The same components have the same reference numerals.

 Referring to FIG. 3, a thin film transistor (Tr) and an organic light emitting display device are disposed on a substrate 100 in red and green sub-pixel regions of an organic light emitting display according to the present invention.

The thin film transistor Tr includes a semiconductor layer 101, a gate electrode 105, a source electrode 107, and a drain electrode 108. The organic electroluminescent device includes a first electrode 111, an organic emission layer 200, and a second electrode 120.

In detail, the semiconductor layer 101 is disposed on the substrate 100. The semiconductor layer 101 includes a source region 101a, a channel region 101b, and a drain region 101c. A gate insulating film 104 is disposed on the semiconductor layer 101. The gate insulating layer 104 may be disposed on the entire surface of the substrate 100 including the semiconductor layer 101.

A gate electrode 105 is disposed on the gate insulating film 104 so as to overlap the channel region 101b of the semiconductor layer 101. [ The gate electrode 105 may be an alloy formed of Cu, Mo, Al, Ag, Ti, Ta, or a combination thereof. Further, although the single metal layer is shown in the drawing, at least two or more metal layers may be laminated.

An interlayer insulating layer 106 is disposed on the gate electrode 105. The interlayer insulating layer 106 may be disposed on the entire surface of the substrate 100 including the gate electrode 105. [ A contact hole for exposing the source region 101 and the drain region 103 is formed in the interlayer insulating layer 106 and the gate insulating layer 104.

Thereafter, a source electrode 107 and a drain electrode 108 are disposed on the contact hole and the interlayer insulating film 106. The source electrode 107 and the drain electrode 108 are connected to the source region 101 and the drain region 103 of the semiconductor layer 100 by the contact holes. The source electrode 107 and the drain electrode 108 may be made of Cu, Mo, Al, Ag, Ti, Ta, or a combination thereof. Further, although the single metal layer is shown in the drawing, at least two or more metal layers may be laminated.

Thus, the thin film transistor Tr is disposed on the substrate 100. However, the structure of the thin film transistor Tr is not limited thereto. Although the top gate structure in which the gate insulating film 104, the gate electrode 105, the source electrode 107, and the drain electrode 108 are sequentially disposed on the semiconductor layer 101 is shown in FIG. The thin film transistor Tr can be changed within a range that does not deviate from the essential characteristics of the embodiment according to the present invention such as a bottom gate structure and a double gate structure.

A protective film 109 is disposed on the substrate 100 on which the thin film transistor Tr is disposed. A planarizing film 100 is disposed on the protective film 109. A contact hole exposing the drain electrode 108 of the thin film transistor Tr is formed in the protective film 109 and the planarization film 110.

A first electrode 111 of the organic electroluminescent device connected to the drain electrode 108 by the contact hole is disposed on the planarization layer 110. At this time, the first electrode 111 may be formed as a single layer made of a transparent conductive material having a relatively high work function value.

The shape of the first electrode 111 is not limited to the drawing, and the first electrode 111 may be formed of multiple layers. For example, a triple-layer structure in which a second layer is formed on the first layer and a third layer is formed on the second layer.

Here, the first layer and the third layer may be transparent conductive materials. For example, the transparent conductive material may be ITO or IZO. The second layer may be a reflective layer. In this case, the second layer may be a metal or a metal alloy layer. For example, a metal alloy layer containing Ag or Ag.

An organic light emitting layer 200 is disposed on the first electrode 111 of the organic electroluminescent device. The organic emission layer 200 includes a hole injection layer 201, a first hole transport layer 202a, a red emission layer 203a, a buffer layer 210, a blue emission layer 203c, an electron transport layer 204, ).

Here, the hole injection layer 201, the first hole transport layer 202a, the red light emitting layer 203a, and the buffer layer 210 may be formed by a solution process. For example, the hole injection layer 201, the first hole transporting layer 202a, the red light emitting layer 203a, and the buffer layer 210 may be formed by ink-jet, spin coating, or slot die ), But the present invention is not limited thereto.

The blue light emitting layer 203c, the electron transporting layer 204, and the electron injection layer 205 may be formed by a vacuum deposition method. For example, it may be formed by a method such as evaporation or CVD (chemical vapor deposition), but is not limited thereto.

At this time, since the buffer layer 210 having a high filling factor is disposed between the red light emitting layer 203a and the blue light emitting layer 203c, the charge balance of the red sub pixel region and the lifetime of the device can be improved. The buffer layer 210 may be formed of a compound represented by Formula 1 below.

[Chemical Formula 1]

In Formula 1, n is an integer of 1 to 100, and R is -H, -OCH _3, or -OCH ₂ CH ₃ .

In addition, the buffer layer 210 is not limited to the drawing, and may be formed of a triple layer. In detail, the buffer layer 210 is disposed on the lower part of the second layer disposed below the blue light emitting layer 203c, the second layer disposed on the lower part of the first layer, As shown in FIG. At this time, the first to third layers of the buffer layer 210 may be made of a compound represented by the following Chemical Formula 1.

[Chemical Formula 1]

In Formula 1, R may be an integer of 1 to 100. In the first layer of the buffer layer 210, R in the formula (1) is -OCH ₂ CH _{3. In} the second layer, R in the formula (1) is -OCH _{3. In} the third layer, -H.

Also, the material of the buffer layer 210 is not limited thereto. The first layer of the buffer layer 210 may be formed of a compound represented by Formula 1 below.

[Chemical Formula 1]

In Formula 1, n is an integer of 1 to 100, and R is -H, -OCH _3, or -OCH ₂ CH ₃ .

The second layer of the buffer layer 210 may be formed of a compound represented by Formula 2 below.

(2)

In Formula 2, k, l and m are each an integer of 1 to 1000, and Formula 2 includes at least one substituted or unsubstituted oxide, oxetane, amine group, phosphine, phenyl group or halogen group.

The third layer of the buffer layer 210 may be formed of a compound represented by the following Chemical Formula 3.

(3)

In Formula 3, R ₁ , R ₂ , R _3, and R ₄ are each independently selected from an alkyl group or an alkenyl group having 1 to 1000 carbon atoms including substituents of a hydroxyl group, a phenyl group, or a halogen group.

A second electrode 120 of the organic electroluminescent device is disposed on the organic light emitting layer 200. The second electrode 120 may be formed of a metal or a metal alloy having a low work function. However, it is not limited thereto and may include a material which can be generally used as a cathode electrode.

Although not shown in the drawing, auxiliary electrodes may be further formed in the display region to lower the voltage drop of the second electrode 120. As described above, the organic electroluminescent device may be disposed on the substrate 100. 3 is not limited to the red subpixel region of the present invention, but may be applied to the green subpixel region as well.

Referring to FIG. 4, a cross-sectional view of a blue sub-pixel region in an organic light emitting display according to the present invention will now be described. 4 is a cross-sectional view of a blue sub-pixel region in an organic light emitting display according to the present invention. The organic light emitting display device according to the present invention may include the same components as those of the above-described embodiments. The description overlapping with the embodiments described above may be omitted. The same components have the same reference numerals.

Referring to FIG. 4, a thin film transistor (Tr) and an organic light emitting display (OLED) are disposed on a substrate 100 in a blue sub pixel region of an organic light emitting display according to the present invention.

The thin film transistor Tr includes a semiconductor layer 101, a gate electrode 105, a source electrode 107, and a drain electrode 108. The organic electroluminescent device includes a first electrode 111, an organic emission layer 201, and a second electrode 120. The organic emission layer 201 includes a hole injection layer 201, a second hole transport layer 202b, a buffer layer 210, a blue emission layer 203c, an electron transport layer 204 and an electron injection layer 205.

Here, the hole injection layer 201, the second hole transport layer 202b and the buffer layer 210 are formed by a solution process. The light emitting layer 203c, the electron transport layer 204, and the electron injection layer 205 are formed by a vacuum evaporation method.

At this time, since the buffer layer 210 having a high filling rate is disposed between the second hole transport layer 202b and the blue light emitting layer 203c, the charge balance of the blue sub pixel region and the lifetime of the device can be improved. The buffer layer 210 may be formed of a compound represented by Formula 1 below.

[Chemical Formula 1]

In Formula 1, n is an integer of 1 to 100, and R is -H, -OCH _3, or -OCH ₂ CH ₃ .

In addition, the buffer layer 210 is not limited to the drawing, and may be formed of a triple layer. In detail, the buffer layer 210 is disposed on the lower part of the second layer disposed below the blue light emitting layer 203c, the second layer disposed on the lower part of the first layer, As shown in FIG. At this time, the first to third layers of the buffer layer 210 may be made of a compound represented by the following Chemical Formula 1.

[Chemical Formula 1]

In Formula 1, n is an integer of 1 to 100. In the first layer of the buffer layer 210, R is -OCH ₂ CH ₃ , R in the second layer is -OCH _3, and R in the third layer is -H.

Also, the material of the buffer layer 210 is not limited thereto. The first layer of the buffer layer 210 may be formed of a compound represented by Formula 1 below.

[Chemical Formula 1]

In Formula 1, n is an integer of 1 to 100, and R is -H, -OCH _3, or -OCH ₂ CH ₃ .

The second layer of the buffer layer 210 may be formed of a compound represented by Formula 2 below.

(2)

In Formula 2, k, l and m are each an integer of 1 to 1000, and Formula 2 includes at least one substituted or unsubstituted oxide, oxetane, amine group, phosphine, phenyl group or halogen group.

The third layer of the buffer layer 210 may be formed of a compound represented by the following Chemical Formula 3.

(3)

In Formula 3, R ₁ , R ₂ , R _3, and R ₄ are each independently selected from an alkyl group or an alkenyl group having 1 to 1000 carbon atoms including a substituent of a hydroxyl group, a phenyl group, or a halogen group.

A second electrode 120 of the organic electroluminescent device is disposed on the organic light emitting layer 200. As described above, the thin film transistor Tr and the organic electroluminescent device may be disposed on the substrate 100.

Hereinafter, the present invention will be described in more detail with reference to experimental examples and comparative examples. However, the following Experimental Examples and Comparative Examples are for illustrating the present invention, and the present invention is not limited to the following Experimental Examples and Comparative Examples, and can be variously modified and changed.

<Experimental Example and Comparative Example>

A method of manufacturing an organic electroluminescent device according to an experimental example of the present invention is described as follows. ITO glass having a sheet resistance of 30 Ω, a thickness of 1.08 mm and a light transmittance of 80% or more was cut into a size of 2 cm × 2 cm, and then the ITO layer was partially removed using an etchant. The ITO glass was washed with an ultrasonic cleaner for 15 minutes each in the order of Acetone, Methanol and IPA, followed by washing with ionized water and drying at 230 ^° C for 30 minutes. The material of the comparative example was spin-coated and dried at 110 ^° C for 1 hour.

A hole injecting layer, a hole transporting layer, and a red or green light emitting layer material were sequentially spin-coated on ITO as an anode electrode. In this case, the hole injection layer was formed using TPD (N, N'-bis- (3-methylphenyl) -N, N'- , 4 '' - Tris ( N- carbazolyl) -triphenylamine).

Thereafter, a buffer layer of a triple layer was spin-coated on the light emitting layer material. At this time, the buffer layer was composed of a first layer, a second layer below the first layer, and a third layer below the second layer. The first to third layers of the buffer layer were formed from a compound represented by the following formula (1).

[Chemical Formula 1]

In the first layer of the buffer layer, n is an integer of 1 and R is -OCH ₂ CH _{3. In} the second layer, n is an integer of 1 and R is -OCH _{3. In} the third layer, n is an integer of 1, -H phosphorus compound. After forming a buffer layer, a blue light emitting layer, an electron transport layer and a cathode were sequentially deposited by evaporation. At this time, the blue light-emitting layer is formed by using TCTA (N, N'-dicarbazolyl-3,5-benzene, 4,4 ', 4 "-tris (N-carbazolyl) triphenylamine): TmPyPb -pyrid-3-yl-phenyl) benzene) to form a blue host, and a dopant was doped with 10% firpic to prepare a device

The manufacturing method of the organic electroluminescent device according to the comparative example is as follows. ITO glass having a sheet resistance of 30 Ω, a thickness of 1.08 mm and a light transmittance of 80% or more was cut into a size of 2 cm × 2 cm, and then the ITO layer was partially removed using an etchant. The ITO glass was washed with an ultrasonic cleaner for 15 minutes each in the order of Acetone, Methanol and IPA, followed by washing with ionized water and drying at 230 ^° C for 30 minutes. And then dried at 110 ^° C for 1 hour through spin coating through the above comparative material.

A hole injecting layer, a hole transporting layer, and a red or green light emitting layer material were sequentially formed on ITO, which is an anode electrode, by spin coating. In this case, the hole injection layer was formed using TPD (N, N'-bis- (3-methylphenyl) -N, N'- , 4 &quot; -tris (N-carbazolyl) -triphenylamine).

Thereafter, a blue light emitting layer, an electron transport layer, and a cathode were sequentially deposited by evaporation. At this time, the blue light-emitting layer was formed by using TCTA (N, N'-dicarbazolyl-3,5-benzene, 4,4 ', 4 "-tris (N-carbazolyl) triphenylamine): TmPyPb -pyrid-3-yl-phenyl) benzene) to form a blue host. The dopant was doped with 10% of firpic.

<Evaluation of Characteristics of Experimental Example and Comparative Example>

When the red light emitting layer is applied, the experimental results of the present invention and the comparative example are shown in Table 1.

Comparative Example
And
Experimental Example Driving voltage
(V) External quantum efficiency
(%) Current efficiency
(Cd / A) Color coordinates
(xy) life span
(h / s) Comparative Example 6.6 10.1 12.8 0.652, 0.346 10.1 Experimental Example 4.2 11.7 12.8 0.664, 0.335 19.4

As can be seen from Table 1, when the red light emitting layer is applied, the results of Experimental Examples and Comparative Examples of the present invention are as follows: Experimental Example shows that the driving voltage is low, the external quantum efficiency is high, It can be seen that the lifetime is long. In addition, the current efficiency of the experimental example was found to be equivalent to that of the comparative example.

FIGS. 5A to 5D are graphs comparing device characteristics according to Experimental Examples and Comparative Examples of the present invention when a red light emitting layer is used. Referring to FIG. 5A, it can be seen that the driving voltage according to the experimental example is significantly lower than the driving voltage according to the comparative example. Referring to FIG. 5B, the current efficiency is high in the low luminance region and high in the high luminance region. Referring to FIG. 5C, it can be seen that the color according to the experimental example appears more clearly than the color according to the comparative example. Also, referring to FIG. 5D, it can be seen that the lifetime of the device according to the experimental example is significantly higher than that of the device according to the comparative example.

Next, in the case of applying the green light emitting layer, the experimental results of the present invention and the comparative example are shown in Table 2.

Comparative Example
And
Experimental Example Driving voltage
(V) External quantum efficiency
(%) Current efficiency
(Cd / A) Color coordinates
(xy) life span
(h / s) Comparative Example 5.0 17.1 63.0 0.321, 0.629 17.3 Experimental Example 4.5 17.0 52.2 0.314, 0.632 20.5

As can be seen from Table 2, when the green light emitting layer is applied, the results of Experimental Examples and Comparative Examples of the present invention are as follows. Experimental Example shows that the driving voltage is low, the current efficiency is remarkably high, It can be seen that the lifetime is long. In addition, the external quantum efficiency of the experimental example was found to be equivalent to that of the comparative example.

6A to 6D are graphs comparing device characteristics according to Experimental Examples and Comparative Examples of the present invention when a green light emitting layer is used. Referring to FIG. 5A, it can be seen that the driving voltage according to the experimental example is somewhat lower than the driving voltage according to the comparative example. Referring to FIG. 6B, it can be seen that the current efficiency is almost the same in the experimental example and the comparative example at the same luminance. Referring to FIG. 6C, it can be seen that the color according to the experimental example appears more clearly than the color according to the comparative example. Also, referring to FIG. 6D, it can be seen that the lifetime of the device according to the experimental example is higher than that of the device according to the comparative example.

The above results show that when the organic light emitting device is manufactured by using the solution process and the vacuum deposition process in combination, the buffer layer according to the present invention is inserted between the layer comprising the solution process and the layer comprising the vacuum deposition process, Respectively.

The features, structures, effects and the like described in the foregoing embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiments may be modified and implemented. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

100: substrate
111: first electrode
120: second electrode
200: organic light emitting layer
201: Hole injection layer
202: hole transport layer
203: light emitting layer
204: electron transport layer
205: electron injection layer
210: buffer layer

Claims (11)

A first electrode on the red sub pixel region, the green sub pixel region, and the blue sub pixel region;
A hole injection layer on the first electrode;
A hole transport layer on the hole injection layer;
Red and green light-emitting layers disposed on the red, green, and blue sub-pixel regions, respectively, disposed on the hole transport layer;
A buffer layer on the hole transport layer in the red and green light emitting layers and the blue sub pixel region;
A blue light-emitting layer on the buffer layer;
An electron transport layer on the blue light emitting layer;
An electron injection layer on the electron transport layer; And
And a second electrode on the electron injection layer.
The method according to claim 1,
The hole transport layer is divided into a first hole transport layer and a second hole transport layer,
Wherein the first hole transport layer is disposed in the red and green sub pixel regions,
And the second hole transport layer is disposed in the blue sub pixel region.
The method according to claim 1,
The lower portion of the buffer layer
A red and a green light emitting layer in the red and green sub pixel regions,
And the second hole transport layer in the blue sub pixel region.
The method according to claim 1,
Wherein the buffer layer comprises a compound represented by the following general formula (1).
[Chemical Formula 1]

In Formula 1,
n is an integer of from 1 to 100, R is -H, -OCH ₃ or -OCH ₂ CH _3.
The method according to claim 1,
Wherein the buffer layer comprises a first layer, a second layer below the first layer, and a third layer below the second layer.
6. The method of claim 5,
The first layer to the third layer of the buffer layer is represented by the following general formula (1), R are each _{-OCH 2 CH 3, -OCH 3,} -H is an organic electroluminescent device.
[Chemical Formula 1]

In Formula 1,
n is an integer of 1 to 100;
6. The method of claim 5,
Wherein the first layer of the buffer layer comprises a compound represented by the following formula (1), the second layer comprises a compound represented by the following formula (2), and the third layer comprises a compound represented by the following formula (3).
[Chemical Formula 1]

In Formula 1,
n is an integer of from 1 to 100, R is -H, -OCH ₃ or -OCH ₂ CH _3.
(2)

In Formula 2,
k, l, and m are each an integer of 1 to 1000,
The formula (2) includes at least one or more substituted or unsubstituted oxides, oxetanes, amine groups, phosphines, phenyl groups or halogen groups.
(3)

In Formula 3,
R ₁ , R ₂ , R _3, and R ₄ are each independently selected from an alkyl group or an alkenyl group having 1 to 1000 carbon atoms including a substituent group of a hydroxyl group, a phenyl group, or a halogen group.
A red sub-pixel region, a red sub-pixel region, a green sub-pixel region, and a blue sub-pixel region;
A thin film transistor on the substrate;
A first electrode electrically connected to the thin film transistor;
A hole injection layer on the first electrode;
A hole transport layer on the hole injection layer;
Red and green light-emitting layers disposed on the red, green, and blue sub-pixel regions, respectively, disposed on the hole transport layer;
A buffer layer on the hole transport layer in the red and green light emitting layers and the blue sub pixel region;
A blue light-emitting layer on the buffer layer;
An electron transport layer on the blue light emitting layer;
An electron injection layer on the electron transport layer; And
And a second electrode on the electron injection layer
Wherein the buffer layer comprises the buffer layer according to any one of claims 2 to 7.
Forming a first electrode on a substrate divided into a red sub pixel region, a green sub pixel region and a blue sub pixel region;
Forming a hole injection layer on the first electrode;
Forming a hole transport layer on the hole injection layer;
Forming red and green light emitting layers disposed on the hole transporting layer and disposed on the red and green sub pixel regions, respectively;
Forming a buffer layer on the hole transporting layer in the red and green light emitting layer and the blue sub pixel region;
Forming a blue light emitting layer on the buffer layer
Sequentially forming an electron transport layer and an electron injection layer on the blue light emitting layer; And
And forming a second electrode on the blue light emitting layer.
10. The method of claim 9,
Wherein the hole injection layer, the hole transport layer, the red light emitting layer, the green light emitting layer, and the buffer layer are formed of a liquid organic light emitting material.
10. The method of claim 9,
Wherein the blue light emitting layer, the electron transporting layer, and the electron injecting layer are formed by a vacuum evaporation method.

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