KR102283913B1 - Organic Light Emitting Diode and Organic Light Emitting Diode Display Device, and Method for Fabricating the Same - Google Patents

Abstract

The present invention discloses an organic light emitting device, an organic light emitting display device having the same, and a method for manufacturing the same. The disclosed organic light emitting device of the present invention, an organic light emitting display device having the same, and a method for manufacturing the same include a hole injection layer on a first electrode disposed on a red sub-pixel region, a green sub-pixel region, and a blue sub-pixel region, , a hole transport layer on the hole injection layer, and red and green light emitting layers disposed on the hole transport layer and respectively disposed on the red and green sub-pixel regions. and a buffer layer on the red and green light emitting layers and the hole transport layer of 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. .

Description

{Organic Light Emitting Diode and Organic Light Emitting Diode Display Device, and Method for Fabricating the Same}

The present invention relates to an organic light emitting device, an organic light emitting display device using the same, and a manufacturing method thereof, and more particularly, to an organic light emitting device capable of improving the driving voltage, lifespan, current characteristics and color coordinates of the device and the same It relates to an organic light emitting display device and a method for manufacturing the same.

Recently, as we enter the information age in earnest, the field of display that visually expresses electrical information signals has developed rapidly, and in response to this, various flat panel display devices ( Flat Display Device) has been developed and is rapidly replacing the existing cathode ray tube (CRT).

Specific examples of such a flat panel display device include a liquid crystal display device (LCD), an organic light emitting display device (OLED), an electrophoretic display device (EPD, Electric Paper Display), Plasma Display Panel device (PDP), Field Emission Display device (FED), Electro luminescence Display Device (ELD) and Electro-Wetting Display (EWD) and the like. They commonly include a flat panel display panel that implements an image as an essential component, and the flat panel display panel includes a pair of face-to-face bonding substrates with a unique light emitting material or polarizing material layer therebetween.

An organic light emitting diode display device, which is one of such flat panel display devices, is a self-luminous device, and since it does not require a separate light source used in a liquid crystal display device that is a non-light emitting device, it can be lightweight and thin. In addition, the viewing angle and contrast ratio are superior to those of the liquid crystal display device, and it is advantageous in terms of power consumption, direct current low voltage driving is possible, the response speed is fast, and the internal component is solid, so it is strong against external shocks and has a wide operating temperature range. It has advantages.

In order to manufacture such an organic light emitting display device with a large area, the hole injection layer, the hole transport layer, the red light emitting layer and the green light emitting layer of the organic light emitting device are formed through a solution process using a liquid organic light emitting material, and the blue light emitting layer, The electron transport layer and the electron injection layer are formed using a vacuum deposition method.

At this time, due to a difference in morphology between the layer formed by the solution process and the layer formed by the vacuum deposition method, a charge accumulation phenomenon occurs. Accordingly, as the charge balance at the interface between the red and green light emitting layers and the blue light emitting layer is lowered, the lifespan of the device is reduced, color purity is lowered, and the like.

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

An organic light emitting diode device of the present invention, an organic light emitting display device having the same, and a method for manufacturing the same, are disposed on a red sub-pixel area, a green sub-pixel area, and a blue sub-pixel area to solve the problems of the prior art a first electrode and a hole injection layer on the first electrode, and a hole transport layer on the hole injection layer and a red and green light emitting layer disposed on the hole transport layer and disposed on the red and green sub-pixel regions, respectively do. and a buffer layer on the red and green light emitting layers and the hole transport layer of 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 a vacuum deposition method. That is, the buffer layer may be disposed on the red light emitting layer and the green light emitting layer formed by the solution process in the red sub-pixel region and the green sub-pixel region and the second hole transport layer formed by the solution process in the blue sub-pixel region.

The buffer layer according to the first embodiment of the present invention may be made 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 include a first layer, a second layer under the first layer, and a third layer under 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 formed of a compound represented by Formula 1, the second layer may include a compound represented by Formula 2, and the third layer may include a 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 having 1 to 1000 carbon atoms or an alkenyl group including a hydroxyl group, a phenyl group, or a halogen group substituent.

The organic electroluminescent device according to the present invention, an organic electroluminescent display device having the same, and a method for manufacturing the same include a red and green light emitting layer by disposing a buffer layer between the red and green light emitting layers and the hole transport layer formed by a solution process and the blue light emitting layer formed by the vacuum deposition method. and interfacial properties between the hole transport layer and the blue light emitting layer. In addition, the organic light emitting diode according to the present invention, an organic light emitting display device having the same, and a method for manufacturing the same have an effect of improving the driving voltage, lifespan, current characteristics and color coordinates of the organic light emitting diode.

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

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are exemplary, and thus the present invention is not limited to the illustrated matters. Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the case in which the plural is included is included unless otherwise explicitly stated.

In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description.

In the case of a description of the positional relationship, for example, when the positional relationship of two parts is described as 'on', 'on', 'on', 'beside', etc., 'right' Alternatively, one or more other parts may be positioned between the two parts unless 'directly' is used.

In the case of a description of a temporal relationship, for example, when a temporal relationship is described as 'after', 'following', 'after', 'before', etc., 'immediately' or 'directly' Unless ' is used, cases that are not continuous may be included.

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

Each feature of the various embodiments of the present invention may be partially or wholly combined or combined with each other, technically various interlocking and driving are possible, and each of the embodiments may be implemented independently of each other or may be implemented together in a related relationship. may be

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. And in the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals refer to like elements throughout.

1 is a diagram schematically illustrating a part of an organic light emitting display device according to a first embodiment of the present invention. Referring to FIG. 1 , in the organic light emitting display device according to the first embodiment of the present invention, a substrate 100 is divided into a red sub-pixel region R, a green sub-pixel region G, and a blue sub-pixel region B. ) and an organic electroluminescent device disposed on it. The organic light emitting 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 illustrated as a single layer in the drawing, the first electrode 111 is not limited thereto, and may be configured as a multi-layer.

A hole injection layer (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 .

In detail, the first hole transport 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 . Through this, it is possible to facilitate hole movement in the organic electroluminescent device. 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 transport layer 202a. In detail, a red light emitting layer 203a is disposed on the first hole transport layer 202a disposed in the red subpixel region R. In addition, a green light emitting layer 203b is disposed on the first hole transport layer 202a disposed in the green sub-pixel region G. As shown in FIG.

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

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

In addition, in the blue sub-pixel region, a charge accumulation phenomenon occurs due to a difference in the interface shape between the hole transport layer formed by the solution process and the blue light emitting layer formed by the vacuum deposition method. Accordingly, the charge balance at the interface between the hole transport layer and the blue light emitting layer is lowered, so that the lifetime of the device is reduced and the color does not appear clearly.

In order to solve this problem, the organic electroluminescent device according to the present invention has a red light emitting layer 203a and a green light emitting layer 203b formed by a solution process in a red sub-pixel region R and a green sub-pixel region G, and a blue sub-pixel region. and a buffer layer 210 disposed on the second hole transport layer 202b formed by the solution process in (b). In this case, since the forward injection layer 201, the hole transport layer 202, the red light emitting layer 203a, and the green light emitting layer 203b are formed by a solution process, it is easy to manufacture a large-area organic light emitting display device.

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

The buffer layer 210 may be formed on the red emission layer 203a, the green emission layer 203b, and the second hole transport layer 202b by a solution process. In this case, the buffer layer may be made of a compound represented by the following formula (1).

[Formula 1]

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

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

Through this, the distance between the molecular chains of the buffer layer 210 and the molecular chains of the red and green light emitting layers 203a and 203b and the second hole transport layer 202b under the buffer layer 210 may become dense. In addition, the distance between the molecular chains of the buffer layer 210 and the molecular chains of the blue light emitting layer 203c on the upper portion of the buffer layer 210 may become dense.

That is, by disposing the buffer layer 210 on the red light emitting layer 203a, the green light emitting layer 203b and the second hole transport layer 202b formed by a solution process, the blue light emitting layer 203b and the buffer layer formed by a vacuum deposition method The interfacial properties between 210 may be improved. In detail, since the upper surface of the buffer layer 210 in contact with the blue light emitting layer 203b is made flat, the interface characteristics between the buffer layer 210 and the blue light emitting layer 203b may be improved.

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

The buffer layer 210 may have a thickness of 1 nm to 100 nm. In this case, when the thickness of the buffer layer 210 is less than 1 nm, it may be difficult to form the buffer layer 210 . In addition, when the thickness of the buffer layer 210 exceeds 100 nm, the charge balance of the organic light emitting device may be reduced.

Also, the buffer layer 210 is not limited thereto, and the buffer layer 210 may further include a photoinitiator. Through this, ring opening polymerization of the material constituting the buffer layer 210 is facilitated, and thus the buffer layer 210 may be advantageous in having a conjugated structure. Accordingly, as the number of π-electrons in the buffer layer 210 increases, the mobility of the buffer layer 210 may be improved.

The photoinitiator may be included in 30% or less in each layer. When the photoinitiator is included in an amount exceeding 30%, the lifespan 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 . The 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 light emitting device of the organic light emitting display device according to the first embodiment of the present invention has a buffer layer 210 on the red light emitting layer 203a, the green light emitting layer 203b, and the second hole transport layer 202b formed by a solution process. With this arrangement, the interface characteristics between the blue light emitting layer 203b and the buffer layer 210 may be improved. Through this, there is an effect of improving the lifespan and color purity of the organic electroluminescent device.

Next, with reference to FIG. 2 , a part of the organic light emitting display device according to the second embodiment of the present invention will be described as follows. 2 is a diagram illustrating a part of an organic light emitting display device 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 above-described embodiment. A description that overlaps with the above-described embodiment may be omitted. Also, the same components have the same reference numerals.

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

In detail, the hole injection layer 201 is disposed on the first electrode 111 , and the 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 transport 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 transport 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 under the second layer 211b. ) can be made. 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 the red and green light emitting layers 203a and 203b and It may be disposed in contact with an upper portion of the second hole transport layer 202b.

The buffer layer 211 may be formed on the red emission layer 203a, the green emission layer 203b, and the second hole transport layer 202b by a solution process. 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 formed of a compound represented by the following Chemical Formula 1.

[Formula 1]

In Formula 1, n may be an integer ranging from 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 addition, R in the third layer 211c may be formed of -H.

A blue light emitting layer 203c is disposed on the first layer 211a of the buffer layer 211 . In this case, the buffer layer 211 may be formed to be bulkier as it is adjacent to the blue light emitting layer 203c. That is, as the buffer layer 211 is adjacent to the blue light emitting layer 203c, the filling rate increases, so that the buffer layer 210 may be disposed on the substrate 100 in a flat shape. Through this, the interface characteristics between the buffer layer 210 and the blue light emitting layer 203c may be improved.

Materials of the first to third layers 211a, 211b, and 211c of the buffer layer 211 are not limited thereto, and may be formed in various ways. For example, the first layer 211a of the buffer layer 211 may be formed of a compound represented by Chemical Formula 1 below.

[Formula 1]

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

In addition, the second layer 211b of the buffer layer 211 may be formed of a compound represented by Chemical Formula 2 below.

[Formula 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.

In addition, the third layer 211c of the buffer layer 211 may be formed of a compound represented by Chemical Formula 3 below.

[Formula 3]

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

That is, the second layer 211b of the buffer layer 211 is made of a material bulkier than the first layer 211a, and the third layer 211c is made of a material bulkier than the second layer 211b. can be done That is, the filling rate of the buffer layer 211 may be sequentially improved. Through this, since the buffer layer 211 is formed to be flat, the interface characteristics between the buffer layer 211 and the blue light emitting layer 203c may be improved.

Each of the first to third layers 211a, 211b, and 211c of the buffer layer 211 may have a thickness of 1 nm to 100 nm. When the first to third layers 211a, 211b, and 211c have a thickness of less than 1 nm, it may be difficult to form the buffer layer 211 . Also, when the thickness of the first to third layers 211a, 211b, and 211c exceeds 100 nm, the charge balance of the organic light emitting diode may be deteriorated.

Also, 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 transport 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 light emitting device of the organic light emitting display device according to the second embodiment of the present invention has a sequential filling rate on the red light emitting layer 203a, the green light emitting layer 203b, and the second hole transport layer 202b, which are formed by a solution process. By disposing the increasing triple-layered buffer layer 210 , the interface characteristics between the blue light emitting layer 203b and the buffer layer 210 may be improved. Through this, there is an effect of improving the lifespan and color purity of the organic electroluminescent device.

Next, with reference to FIG. 3 , a cross-sectional view of the red sub-pixel region in the organic light emitting display device according to the present invention is as follows. 3 is a cross-sectional view illustrating a red sub-pixel region in an organic light emitting display device 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. A description that overlaps with the above-described embodiments may be omitted. Also, the same components have the same reference numerals.

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

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 light emitting device includes a first electrode 111 , an organic light emitting 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 layer 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 layer 104 to overlap the channel region 101b of the semiconductor layer 101 . The gate electrode 105 may be an alloy formed from Cu, Mo, Al, Ag, Ti, Ta, or a combination thereof. In addition, although it is formed as a single metal layer in the drawings, it may be formed by stacking at least two or more metal layers in some cases.

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 layer 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 hole. Here, the source electrode 107 and the drain electrode 108 may be an alloy formed from Cu, Mo, Al, Ag, Ti, Ta, or a combination thereof. In addition, although it is formed as a single metal layer in the drawings, it may be formed by stacking at least two or more metal layers in some cases.

As described above, 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 figure shows a top gate structure in which a gate insulating layer 104 , a gate electrode 105 , a source electrode 107 , and a drain electrode 108 are sequentially disposed on the semiconductor layer 101 . The thin film transistor Tr can be changed within a range without departing from essential characteristics of the embodiment according to the present invention, such as a bottom gate structure and a double gate structure.

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

A first electrode 111 of the organic light emitting device connected to the drain electrode 108 by the contact hole is disposed on the planarization layer 110 . In this case, the first electrode 111 may be formed of 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 drawings, and the first electrode 111 may be formed in multiple layers. For example, it may be formed in a triple-layer structure in which a second layer is formed on a first layer and a third layer is formed on the second layer.

Here, the first layer and the third layer may be a transparent conductive material. 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, it may be Ag or a metal alloy layer containing Ag.

An organic light emitting layer 200 is disposed on the first electrode 111 of the organic light emitting 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 and an electron injection layer 205 . ) is composed of

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 transport 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 is not limited thereto.

In addition, the blue light emitting layer 203c, the electron transport 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.

In this case, 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, charge balance in the red sub-pixel region and lifespan of the device can be improved. The buffer layer 210 may be formed of a compound represented by Chemical Formula 1 below.

[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 drawings, and may be formed of a triple layer. In detail, the buffer layer 210 is a first layer disposed under the blue light-emitting layer 203c, a second layer disposed under the first layer, and disposed under the second layer, and is disposed on the red light-emitting layer 203a. It may be composed of a third layer disposed on the In this case, the first to third layers of the buffer layer 210 may be formed of a compound represented by the following Chemical Formula 1.

[Formula 1]

In Formula 1, it may be an integer ranging from 1 to 100. In addition, in the first layer of the buffer layer 210, R of Formula 1 is -OCH ₂ CH _{3 In} the second layer, R of Formula 1 is -OCH ₃ , and in the third layer, R of Formula 1 is can be -H.

In addition, 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 Chemical Formula 1 below.

[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 second layer of the buffer layer 210 may be made of a compound represented by the following formula (2).

[Formula 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.

In addition, the third layer of the buffer layer 210 may be made of a compound represented by the following Chemical Formula 3.

[Formula 3]

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

The second electrode 120 of the organic light emitting 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, the present invention is not limited thereto, and in general, it may include a material that can be used as a cathode electrode.

In addition, although not shown in the drawings, an auxiliary electrode may be further formed in the display area to lower the voltage drop of the second electrode 120 . In this way, an organic electroluminescent device may be disposed on the substrate 100 . 3 is not only applicable to the red sub-pixel region of the present invention, but may equally be applied to the green sub-pixel region.

Next, with reference to FIG. 4 , a cross-sectional view of the blue sub-pixel region in the organic light emitting display device according to the present invention is as follows. 4 is a cross-sectional view illustrating a blue sub-pixel region in an organic light emitting display device 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. A description that overlaps with the above-described embodiments may be omitted. Also, the same components have the same reference numerals.

Referring to FIG. 4 , the blue sub-pixel region of the organic light emitting display device according to the present invention includes a thin film transistor Tr disposed on a substrate 100 and the organic light emitting display device.

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 light emitting device includes a first electrode 111 , an organic light emitting layer 201 , and a second electrode 120 . The organic light emitting layer 201 includes a hole injection layer 201 , a second hole transport layer 202b , a buffer layer 210 , a blue light emitting 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. In addition, the light emitting layer 203c, the electron transport layer 204, and the electron injection layer 205 are formed by a vacuum deposition method.

In this case, since the buffer layer 210 having a high filling factor 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 lifespan of the device may be improved. The buffer layer 210 may be formed of a compound represented by Chemical Formula 1 below.

[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 drawings, and may be formed of a triple layer. In detail, the buffer layer 210 is a first layer disposed under the blue light-emitting layer 203c, a second layer disposed under the first layer, and disposed under the second layer, and is disposed on the red light-emitting layer 203a. It may be composed of a third layer disposed on the In this case, the first to third layers of the buffer layer 210 may be formed of a compound represented by the following Chemical Formula 1.

[Formula 1]

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

In addition, 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 Chemical Formula 1 below.

[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 second layer of the buffer layer 210 may be made of a compound represented by the following formula (2).

[Formula 2]

In Formula 2, k, 1 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 addition, the third layer of the buffer layer 210 may be formed of a compound represented by the following Chemical Formula 3.

[Formula 3]

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

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

Hereinafter, it will be described in more detail using the experimental examples and comparative examples of the present invention. However, the following experimental examples and comparative examples are intended to illustrate the present invention, and the present invention is not limited to the following experimental examples and comparative examples, and may be variously modified and changed.

<Experimental Examples and Comparative Examples>

A method of manufacturing an organic electroluminescent device according to an experimental example in the present invention 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 x 2 cm, and the ITO layer was partially removed using an etchant. ITO glass was washed with an ultrasonic cleaner for 15 minutes each in the order of Acetone, Methanol, and IPA, washed with ionized water, and dried at 230 ^o C for 30 minutes. Spin coating was carried out through the material of the comparative example and ^{dried at 110 o} C for 1 hour.

A hole injection layer, a hole transport layer, and a red or green light emitting layer material were sequentially spin-coated on the anode electrode, ITO. At this time, the hole injection layer was formed using TPD (N,N'-bis-(3-methylphenyl)-N,N'-bis-(phenyl)-benzidine), and the hole transport layer was TCTA:4,4',4''-Tris ( N- carbazolyl)-triphenylamine) was used.

After that, a triple-layered buffer 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 under the first layer, and a third layer under the second layer. The first to third layers of the buffer layer were formed of a compound represented by the following formula (1).

[Formula 1]

In the first layer of the buffer layer, n is an integer 1 and R is -OCH ₂ CH ₃ , in the second layer n is an integer 1 and R is -OCH ₃ , in the third layer n is an integer 1 and R is -H was composed of the compound. After the buffer layer was formed, a blue light emitting layer, an electron transport layer, and a cathode electrode were sequentially deposited using evaporation. At this time, the blue light emitting layer is TCTA(N,N'-dicarbazolyl-3,5-benzene,4,4',4''-tris(N-carbazolyl)triphenylamine):TmPyPb(1,3,5-tri(m) -pyrid-3-yl-phenyl)benzene) was used to form a blue host, and as a dopant, firpic was doped in an amount of 10% to fabricate 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 x 2 cm, and the ITO layer was partially removed using an etchant. ITO glass was washed with an ultrasonic cleaner for 15 minutes each in the order of Acetone, Methanol, and IPA, washed with ionized water, and dried at 230 ^o C for 30 minutes. Through spin coating through the material of the comparative example, it ^{was dried at 110 o} C for 1 hour.

A hole injection layer, a hole transport layer, and a red or green light emitting layer material were sequentially prepared through spin coating on the anode electrode, ITO. At this time, the hole injection layer was formed using TPD (N,N'-bis-(3-methylphenyl)-N,N'-bis-(phenyl)-benzidine), and the hole transport layer was TCTA:4,4' ,4''-tris (N-carbazolyl)-triphenylamine) was used.

Thereafter, a blue light emitting layer, an electron transport layer, and a cathode electrode were sequentially deposited using evaporation. At this time, the blue light emitting layer is TCTA(N,N'-dicarbazolyl-3,5-benzene,4,4',4''-Tris(N-carbazolyl)triphenylamine):TmPyPb(1,3,5-tri(m) -pyrid-3-yl-phenyl)benzene) was used to form a blue host, and the device was fabricated by doping 10% of firpic as a dopant.

<Characteristic evaluation of experimental examples and comparative examples>

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

comparative example
and
Experimental example drive 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 in Table 1, when a red light emitting layer is applied, looking at the results of the experimental examples and comparative examples of the present invention, the experimental example has a lower driving voltage, higher external quantum efficiency, and a clear color than the comparative example, It can be seen that the lifespan is long. In addition, the current efficiency of the experimental example was found to be at the same level as that of the comparative example.

5A to 5D are graphs comparing device characteristics according to the Experimental Example and Comparative Example 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 , it was found that the comparative example was high in the low luminance region, and the experimental example was high in the high luminance region. Referring to FIG. 5C , it can be seen that the color according to the experimental example appears somewhat more vividly 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.

Then, when the green light emitting layer was applied, the experimental results of the experimental examples and comparative examples of the present invention are shown in Table 2.

comparative example
and
Experimental example drive 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 in Table 2, when a green light emitting layer is applied, looking at the results of the experimental examples and comparative examples of the present invention, the experimental example has a lower driving voltage, a significantly higher current efficiency, and a clear color than the comparative example, It can be seen that the lifespan is long. In addition, the external quantum efficiency of the experimental example was found to be at the same level as that of the comparative example.

6A to 6D are graphs comparing device characteristics according to the Experimental Example and Comparative Example 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 slightly 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 somewhat more vividly 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 an organic electroluminescent device is manufactured by mixing a solution process and a vacuum deposition method, the device characteristics can be improved by inserting the buffer layer according to the present invention between the layer made of the solution process and the layer made of the vacuum deposition method. show that there is

Features, structures, effects, etc. described in the above-described embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to one embodiment. Furthermore, features, structures, effects, etc. illustrated in each embodiment can be combined or modified for other embodiments by those of ordinary skill in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

In addition, although the embodiments have been described above, these are merely examples and do not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are exemplified above in a range that does not depart from the essential characteristics of the present embodiment. It can be seen that various modifications and applications that have not been made are possible. For example, each component specifically shown in the embodiments may be implemented by modification. And the differences related to these modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

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 (13)

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 including a first hole transport layer disposed on the hole injection layer in the red and green sub-pixel regions and a second hole transport layer disposed on the hole injection layer in the blue sub-pixel region;
red and green light emitting layers disposed on the hole transport layer and respectively disposed on red and green sub-pixel regions;
a buffer layer on the red and green light emitting layers and the hole transport layer of 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;
a lower portion of the buffer layer contacts the red and green light emitting layers in the red and green sub-pixel regions, and contacts the second hole transport layer in the blue sub-pixel region;
The buffer layer is an organic electroluminescent device comprising a compound represented by the following formula (1).
[Formula 1]

In Formula 1,
n is an integer from 1 to 100, and R is -H, -OCH ₃ or -OCH ₂ CH ₃ .
delete delete delete The method of claim 1,
The buffer layer is an organic electroluminescent device comprising a first layer, a second layer under the first layer, and a third layer under the second layer.
6. The method of claim 5,
The first to third layers of the buffer layer are represented by the following Chemical Formula 1, and R is -OCH ₂ CH ₃ , -OCH ₃ , -H, respectively.
[Formula 1]

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

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

In Formula 2,
k,l and m are each an integer from 1 to 1000,
Formula 2 includes at least one substituted or unsubstituted oxide, oxetane, amine group, phosphine, phenyl group, or halogen group.
[Formula 3]

In Formula 3,
R ₁ , R ₂ , R _{3 ,} and R ₄ are each independently selected from an alkyl group having 1 to 1000 carbon atoms or an alkenyl group including a hydroxyl group, a phenyl group, or a halogen group substituent.
a substrate divided into 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 including a first hole transport layer disposed on the hole injection layer in the red and green sub-pixel regions and a second hole transport layer disposed on the hole injection layer in the blue sub-pixel region;
red and green light emitting layers disposed on the hole transport layer and respectively disposed on red and green sub-pixel regions;
a buffer layer on the red and green light emitting layers and the hole transport layer of 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;
a lower portion of the buffer layer contacts the red and green light emitting layers in the red and green sub-pixel regions, and contacts the second hole transport layer in the blue sub-pixel region;
The buffer layer is an organic light emitting display device including a compound represented by the following formula (1).
[Formula 1]

In Formula 1,
n is an integer from 1 to 100, and R is -H, -OCH ₃ or -OCH ₂ CH ₃ .
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 transport layer and respectively disposed on red and green sub-pixel regions;
forming a buffer layer on the red and green light emitting layers and the hole transport layer of 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
Including; forming a second electrode on the blue light emitting layer;
In the step of forming the buffer layer, a lower portion of the buffer layer is formed to contact the red and green light emitting layers in the red and green sub-pixel regions and to contact the hole transport layer in the blue sub-pixel region,
The buffer layer is a method of manufacturing an organic light emitting display device including a compound represented by the following formula (1).
[Formula 1]

In Formula 1,
n is an integer from 1 to 100, and R is -H, -OCH ₃ or -OCH ₂ CH ₃ .
10. The method of claim 9,
The hole injection layer, the hole transport layer, the red light emitting layer, the green light emitting layer and the buffer layer are organic light emitting display device manufacturing method is formed of a liquid organic light emitting material.
10. The method of claim 9,
The blue light emitting layer, the electron transport layer and the electron injection layer are formed by a vacuum deposition method for an organic light emitting display device manufacturing method. 9. The method of claim 8,
The buffer layer consists of a first layer, a second layer under the first layer, and a third layer under the second layer,
The first to third layers may include the compound represented by Chemical Formula 1 above.
9. The method of claim 8,
The buffer layer consists of a first layer, a second layer under the first layer, and a third layer under the second layer,
The first layer of the buffer layer is made of a compound represented by the following formula (1), the second layer is made of a compound represented by the following formula (2), and the third layer is made of a compound represented by the following formula (3).
[Formula 1]

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

In Formula 2,
k,l and m are each an integer from 1 to 1000,
Formula 2 includes at least one substituted or unsubstituted oxide, oxetane, amine group, phosphine, phenyl group, or halogen group.
[Formula 3]

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

Images