KR20190054722A - Electroluminescence display device - Google Patents

Abstract

An electroluminescent display device of the present invention is provided to minimize light loss. The electroluminescent display device comprises: a first electrode and a second electrode arranged on a substrate; a light emitting layer arranged between the first electrode and the second electrode; a reflective layer arranged on a lower part of the first electrode and reflecting light incident from the light emitting layer; and an optical path adjusting layer arranged between the first electrode and the reflective layer, and suppressing the generation of surface plasmon at an interface of the first electrode and the reflective layer.

Description

ELECTROLUMINESCENCE DISPLAY DEVICE [0002]

The present invention relates to an electroluminescence display device capable of improving light efficiency by minimizing light loss caused by a surface plasmon.

Recently, an electroluminescent device using poly (p-phenylenevinylene) (PPV), which is one of conjugate polymers, has been developed and research on organic materials such as conjugated polymers having conductivity has been actively conducted. Studies for applying such organic materials to thin film transistors (TFTs), sensors, lasers, photoelectric elements, etc. have been continuing, and researches on electroluminescent display devices have been actively conducted.

In the case of an electroluminescent device composed of inorganic phosphors, a driving voltage is required to be 200 V or more in alternating current, and since the manufacturing process of the device is formed by vacuum deposition, it is difficult to increase the size of the device. Especially, have. However, an electroluminescent device made of an organic material is advantageous in that it can develop an electroluminescent device capable of easily producing an electroluminescent device with excellent luminescence efficiency, facilitating large-sized surface preparation, simplifying the process, And is spotlighted as a display device.

Currently, an active matrix electroluminescent display device having an active driving element in each pixel is actively studied as a panel display device in the same manner as a liquid crystal display device.

However, in the electroluminescent display device described above, only about 20% of the light emitted from the light emitting layer is output to the outside, and about 80% of the light is lost, so that the light extraction efficiency is low.

An object of the present invention is to provide an electroluminescent display device capable of suppressing the generation of surface plasmon in the device and improving light extraction efficiency.

Another object of the present invention is to provide an electroluminescent display device capable of improving the light extraction efficiency and achieving a clear color by optimizing the optical path length of the micro cavity formed inside the device in the R, G, and B pixels.

According to one aspect of the present invention, an electroluminescent display includes a first electrode and a second electrode disposed on a substrate, a light emitting layer disposed between the first electrode and the second electrode, A reflective layer for reflecting the light incident from the light emitting layer and an optical path control layer disposed between the first electrode and the reflective layer and suppressing the generation of surface plasmon at the interface between the first electrode and the reflective layer.

According to another aspect of the present invention, an electroluminescent display device includes a substrate including R, G, and B pixels, and a second electrode formed on the substrate and disposed between the first electrode, the second electrode, And the light path lengths of the micro cavity structures of the R, G and B pixels are different from each other, and the optical path length is adjusted according to the thickness of the first electrode.

The present invention can prevent formation of surface plasmons by preventing the interface between the metal film and the organic material by disposing the light path control layer between the transparent electrode made of a metal and a reflective layer made of an organic material such as a metal oxide or a conductive polymer , The light loss due to the surface plasmon can be minimized and the light extraction efficiency of the electroluminescence display device can be improved.

In the present invention, since the optical path adjusting layer is disposed between the transparent electrode and the reflective layer, the reflective layer and the transparent electrode are separated from each other by a predetermined distance by the optical path control layer, so that the display by the surface plasmon generated at the interface between the metal layer and the organic layer It is possible to prevent light loss in the apparatus.

In addition, the present invention adjusts the optical path adjusting layer so that the optical path length of the micro cavities of the R, G, and B pixels corresponds to the peak wavelength of R, G, B monochromatic light, The light extraction efficiency is improved and the width of the emission spectrum of the outputted monochromatic light is narrowed, so that light of high purity can be outputted.

1 is a cross-sectional view illustrating a structure of an electroluminescent display device according to a first embodiment of the present invention.
2 is a cross-sectional view showing the structure of an electroluminescent display device having R, G, and B pixels of the present invention.
3 is a cross-sectional view illustrating a structure of an electroluminescent display device according to a first embodiment of the present invention.
4A through 4E illustrate a method of manufacturing an electroluminescent display device according to a first embodiment of the present invention.
5 is a cross-sectional view illustrating a structure of an electroluminescent display device according to a second embodiment of the present invention.
6 is a cross-sectional view illustrating a structure of an electroluminescent display device according to a third embodiment of the present invention.
7 is a cross-sectional view showing a structure of an electroluminescent display device according to a third embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to 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 the temporal relationship is described by 'after', 'after', 'after', 'before', etc., May not be continuous unless they are not 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, the present invention will be described in detail with reference to the accompanying drawings.

In general, the light efficiency of the electroluminescent display device is low because of the following reasons.

First, the light efficiency is lowered due to the waveguide phenomenon in the electroluminescence display device. The electroluminescence display device is composed of a plurality of layers having different refractive indexes. Therefore, when the light emitted from the light emitting layer is output to the outside through a plurality of lights, the light is refracted and propagated at a certain angle due to the difference in refractive index at the interface between the plurality of layers. For example, when the incident angle of the light incident on the interface of the layer is greater than the critical angle with respect to the normal, the incident light is reflected at the interface, and the reflected light propagates along the inside of the layer without being output to the outside. In other words, a part of light emitted from the light emitting layer can not be output to the outside, but is trapped inside the EL display device.

Second, the light efficiency of the electroluminescence display device is lowered by the surface plasmon. Surface plasmons are waves that propagate along the interface between a waveguide metal and a dielectric material caused by the collective oscillation of electrons in the metal film. The electric field of the light in the visible light band among the light emitted from the light emitting layer is mated with the surface plasmon, so that light absorption occurs and a large part of the light is lost in the form of surface plasmon.

In the present invention, efficiency deterioration due to surface plasmon is prevented from being a cause of efficiency reduction of the electroluminescent display device, and will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view illustrating a structure of an electroluminescent display device according to a first embodiment of the present invention.

1, the electroluminescent display includes a first electrode 130 and a second electrode 142 formed on a first substrate 110, a first electrode 130 and a second electrode 142 And a second substrate 150 attached by an adhesive layer 152 applied on the second electrode 142. The light emitting layer 140 emits light when a signal is applied thereto. The electroluminescent display device is a top emission display device in which light emitted from the light emitting layer 140 is output in an upward direction.

The first electrode 130 is an anode and includes a reflective layer 132 made of a metal having a high reflectivity such as Al, Ag, Au, or an alloy thereof and reflecting the light emitted from the light emitting layer 142, A light path control layer 134 disposed on the reflective layer 132 and a transparent electrode 136 formed on the light path control layer 134.

The transparent electrode 136 may be formed of a metal oxide such as ITO (Indium Tin Oxide), IGZO (Indium Gallium Zinc Oxide), or IZO (Indium Tin Oxide) or a transparent conductive polymer. The conductive polymer may be poly (3,4, -ethylene dioxythiophene), PEDOT-PSS, polyacetylene, polyparenylene, polyphenol, polyaniline or the like. It is not. The light path control layer 134 is made of an inorganic material having a refractive index similar to that of the transparent electrode 136.

The light emitting layer 140 may be a monochromatic light emitting layer in which R, G, and B monochromatic light are emitted, or may be a white light emitting layer in which white light is emitted. When the light emitting layer 140 is a white light emitting layer, the light emitting layer 140 may include a plurality of organic materials that emit red, green, and blue monochromatic light, A light emitting layer may be laminated and a color filter layer may be provided on the light emitting layer. The light emitting layer 140 may be formed of an inorganic material. For example, it may be a quantum dot. The light emitting layer 140 includes a light emitting layer that emits light when a voltage is applied from the first electrode 130 and the second electrode 142, an electron injection layer and a hole injection layer that inject electrons and holes into the light emitting layer, respectively, An electron transport layer and a hole transport layer that transport the injected electrons and holes to the light emitting layer, respectively. The light emitting layer for emitting light may be composed of a single layer or a multi-layered or stacked structure such as a tandem structure.

The second electrode 142 may be formed of a transparent metal oxide such as ITO, IGZO, or IZO as a cathode. Alternatively, the second electrode 142 may be formed as a semitransparent electrode layer by forming a thin metal such as Al or Ag, The reason for this is to form a microcavity structure between the reflective layer 132 of the first electrode 130 and the semitransparent second electrode 142.

The micro cavity improves the light extraction efficiency by using the reinforcing interference effect of the wavelength. Since the second electrode 142 has a resonant structure between the reflective layer 132 and the semi-transparent second electrode 142, if the same period and phase are continuously overlapped, the energy is amplified to generate a micro cavity effect and the emitted light is emitted in the vertical direction . By this microcavity, the light of a specific wavelength can be selectively emitted, and the width of the spectrum can be reduced, so that a clearer light than the original color can be realized.

The optical path control layer 134 of the first electrode 130 removes surface plasmons to prevent light loss due to surface plasmons. Surface plasmons are locally present on the surface of the metal film as similar particles in which free electrons induced in the surface of the metal film by the electric field of incident light are collectively vibrated. Such surface plasmons occur mainly at the interface between the metal film and the organic material, and absorb light transmitted through the interface, thereby causing light loss.

In the present invention, the light path control layer 134 is disposed between the reflective layer 132 made of a metal and the transparent electrode 136 made of an organic material such as a metal oxide or a conductive polymer, so that the metal film and the organic material do not form a direct interface It is possible to prevent surface plasmon from being formed at the interface between the metal material and the organic material.

In the case of an electroluminescent display having a structure in which the first electrode 130 is formed of one metal layer and a light is emitted from the light emitting layer 140 while a signal is applied to the light emitting layer 140, And between the first electrode 130 and the light emitting layer 140. Therefore, in the case of this electroluminescence display device, the light path control layer 134 may be disposed between the first electrode 130 and the light emitting layer 140 to remove or suppress the surface plasma generated between the metal film and the organic material. have.

However, in such a structure, the brightness of the electroluminescence display device is lowered by the light path control layer 134 disposed between the first electrode 130 and the light emitting layer 140. In order to prevent the luminance charge, the voltage applied to the first electrode 130 must be increased to increase the power consumption of the electroluminescence display device.

The present invention is not limited to disposing a separate light path control layer 134 between the metal film and the organic material in order to remove the surface plasmon generated in the electroluminescence display device, The light path control layer 134 is disposed between the reflective layer 132 and the transparent electrode 136. The reflective layer 132 and the transparent electrode 136 may be formed of a single metal layer.

Therefore, in the present invention, since the light path control layer 134 is not disposed between the transparent electrode 136 to which the actual voltage is applied and the light emitting layer 140, the luminance of the light path control layer 134 can be prevented from being lowered . A microcavity can be formed by the reflective layer 132 and the second electrode 142.

As described above, in the present invention, the actual voltage is applied to the transparent electrode 136, and the reflective layer 132 can reflect incident light. The light path control layer 134 can remove surface plasmons. Although the reflective layer 132, the light path control layer 134 and the transparent electrode 136 are referred to as one first electrode, for example, an anode in the drawings and the above description, only the transparent electrode 136 is an anode or a It may be referred to as one electrode.

The light path control layer 134 may be configured to control not only the surface plasmon of the electroluminescence display device but also the light having the optimum wavelength corresponding to the color by controlling the optical path length of the micro cavity of the electroluminescence display device, By outputting light having a small wavelength in the spectrum, a clear color can be realized.

This will be described with reference to FIG. 2 is a diagram showing the structure of an electroluminescent display device having R, G, and B pixels.

2, the reflective layer 132, the light path control layers 134R, 134G, and 134B, and the reflective layer 132 are formed on the R, G, and B pixels disposed on the first substrate 110 and the second substrate 150, respectively. An electrode 136, a light emitting layer 140, a second electrode 142, and an adhesive layer 152 are disposed. The thicknesses of the reflective layer 132, the transparent electrode 136, the light emitting layer 140, the second electrode 142, and the adhesive layer 152 are the same for R, G, and B pixels, , 134G, and 134B are different from each other in the R, G, and B pixels.

For example, the thickness d1 of the light path control layer 134R of the R pixel, the thickness d2 of the light path control layer 134G of the G pixel, the thickness d3 of the light path control layer 134B of the B pixel ) Can have a relationship of d1 < d2 < d3.

In the electroluminescent display, the microcavity is formed between the reflective layer 132 of the first electrode 130 and the second electrode 142 having a semi-transmissive property, and the optical path length of the microcavity in the R, G, L1, L2, and L3 may have a relationship of L1 < L2 < L3. The optical path lengths L1, L2 and L3 of the microcavities are set to be the same as the thicknesses of the optical path control layers (d1, d2 and d3) except for the thicknesses d1, d2 and d3 of the optical path control layers 134R, 134G and 134B. 134R, 134R, 134R, 134G, and 134B.

Therefore, the electroluminescent display device according to the present invention can adjust the thickness d1, d2, and d3 of the light path control layers 134R, 134G, and 134B so that the light path lengths of the microcavities in the R, (L1, L2, L3). By adjusting the light path lengths (L1, L2, L3), the spectral width of specific color light output from the pixel can be narrowed, so that a clear color can be realized.

The wavelength? Of the corresponding color light output from each of the R, G, and B pixels satisfies the following expression (1).

Where n is the refractive index of the material of the microcavity of the electroluminescent display and L is the length of the microcavity (e.g., the distance between the reflective layer 132 and the second electrode 142) and m (m = 1, , 3 ...) is the mode index of the particular mode.

As shown in Equation 1, the wavelength? Of light output from the R, G and B pixels is determined according to the optical path length L of the microcavity, and the optical path length L of the microcavity is the optical path length? G and B colors outputted from the R, G and B pixels are determined according to the thickness d of the control layer 134. The wavelength? Is determined according to the thicknesses (d1, d2, d3).

Thus, by setting the thicknesses of the light path control layers 134R, 134G, and 134B formed in the R, G, and B pixels to correspond to the peak wavelengths of R, G, and B monochromatic light, So that light of high color can be outputted.

Since the wavelength of the B-color is about 440-460 nm, the wavelength of the G-color is about 520-550 nm, and the wavelength of the R-color is about 600-650 nm, the light path control layers 134R, 134G D2, and d3 of the light emitting diodes 134a and 134b are set to d1 > d2 > d3, monochromatic light with high purity can be output from the electroluminescence display device.

Therefore, the electroluminescent display device according to the present invention is applicable to an electroluminescent display device in which the light-path control layers 134R, 134G (corresponding to the peak wavelengths of R, G, B monochromatic light of different thicknesses, for example, And 134B, the light extraction efficiency can be improved by the effect of constructive interference of the wavelength by the microcavity, and the light emission spectrum of the outputted monochromatic light can be narrowed to output light of high color.

The light path control layer 134 can prevent surface plasmon from being generated between the metal layer and the organic layer by separating the reflective layer 132, which is a metal layer, from the transparent electrode 134, which is an organic layer, The extraction efficiency can be further improved.

3 is a cross-sectional view illustrating a structure of an electroluminescent display device according to a first embodiment of the present invention. As shown in FIG. 2, the thicknesses of the light path control layers 134 formed on the R, G, and B pixels are different from each other. However, only one pixel is shown in FIG. 3 for convenience of explanation.

As shown in FIG. 3, a buffer layer 112 is formed on the first substrate 110, and a driving thin film transistor is disposed thereon. The substrate 110 uses a transparent material such as glass, but transparent and flexible plastic such as polyimide may also be used. The buffer layer 112 may be formed of a single layer or a plurality of layers.

The driving thin film transistor is formed in each of the plurality of pixel regions. The driving thin film transistor includes a semiconductor layer 122 formed in a pixel region on the buffer layer 112, a gate insulating layer 123 formed on a partial region of the semiconductor layer 122, An interlayer insulating layer 114 formed over the entire substrate 110 to cover the gate electrode 125 and an interlayer insulating layer 114 disposed on the interlayer insulating layer 114, And a source electrode 127 and a drain electrode 128 which are connected to the semiconductor layer 122 through a first contact hole 114a formed in the semiconductor layer 122. [ The source electrode 127 is connected to the semiconductor layer 122 through the first contact hole 114a formed in the interlayer insulating layer 114. The drain electrode 128 is connected to the semiconductor layer 122, .

The semiconductor layer 122 may be formed of an oxide semiconductor such as crystalline silicon or IGZO (Indium Gallium Zinc Oxide). The semiconductor layer 122 may include a channel layer in the central region and a doped layer on both sides, Is in contact with the doped layer.

The gate electrode 125 and the interlayer insulating layer 114 may be formed of a metal such as Cr, Mo, Ta, Cu, Ti, Al or an Al alloy. The gate insulating layer 123 and the interlayer insulating layer 114 may be formed of a metal such as SiOx or SiNx A single layer made of an insulating material or an inorganic layer made of a two-layered structure of SiOx and SiNx. The source electrode 127 and the drain electrode 128 may be formed of Cr, Mo, Ta, Cu, Ti, Al, or Al alloy.

In the drawings and the above description, the driving thin film transistor has a specific structure. However, the driving thin film transistor of the present invention is not limited to the illustrated structure, but can be applied to all the driving thin film transistors.

A protective layer 116 is formed on the substrate 110 on which the driving thin film transistor is formed. The protective layer 116 may be formed of an organic material such as photoacryl.

A reflective layer 132 is formed on the protective layer 116. The reflective layer 132 may be formed of a metal such as Al, Au, or Ag, or an alloy thereof. However, the reflective layer 132 is not limited thereto. The reflective layer 132 may be a single layer or a plurality of layers.

On the reflective layer 132, a light path control layer 134 is formed. The light path control layer 134 is made of a transparent material so as to not only separate the metal layer and the organic layer from each other by a certain distance but also adjust the optical path length of the microcavity. As the light path control layer 134, an inorganic material such as SiOx or SiNx may be used, but various inorganic materials may be used. The light path control layer 134 may be formed of a single layer or a plurality of layers. When formed of a plurality of layers, each layer may be composed of different materials.

A transparent electrode 136 is formed on the light path control layer 134. The transparent electrode 136 may be formed of a metal oxide such as ITO, IGZO or IZO or a conductive plastic such as poly (3,4-ethylene dioxythiophene), PEDOT-PSS, Conductive polymers such as acetylene, polypararylene, polyphenol, polyaniline and the like can be used, but are not limited to these materials.

A second contact hole 116a is formed in the protective layer 116, the reflective layer 132 and the optical path control layer 134. The transparent electrode 136 is electrically connected to the thin film transistor through the second contact hole 116a. Drain electrode 128, as shown in FIG.

A bank layer 138 is formed at the boundary of each pixel on the transparent electrode 136. The bank layer 138 is a kind of barrier rib, and it is possible to divide each pixel and prevent light of a specific color outputted from adjacent pixels from being mixed and outputted. Although the bank layer 138 is formed on the transparent electrode 136 in the drawing, the bank layer 138 may be formed on the protection layer 116 and the transparent electrode 136 may be formed on the bank layer 138 .

A light emitting layer 140 is formed on the first electrode 136 and the bank layer 138. The organic light emitting layer 140 may be an R-light emitting layer formed on R, G, or B pixels to emit red light, a G-light emitting layer emitting green light, or a B-light emitting layer emitting blue light, And may be a white light emitting layer emitting white light. When the light emitting layer 140 is a white light emitting layer, R, G and B color filter layers are formed in an upper region of the white light emitting layer 140 of R, G and B pixels to convert white light emitted from the white light emitting layer into red light, . The white light emitting layer may be formed by mixing a plurality of materials for emitting monochromatic light of R, G, and B, respectively, or by laminating a plurality of light emitting layers for emitting monochromatic light of R, G, and B, respectively.

The light emitting layer 140 may include an electron injection layer for injecting electrons and holes into the light emitting layer, an electron injection layer for injecting electrons and holes, and an electron transport layer and a hole transport layer for transporting the injected electrons and holes to the light emitting layer, respectively.

A second electrode 142, which is a cathode, is formed on the light emitting layer 140. The second electrode 142 is formed of a metal such as Al, Ag, or Au. The second electrode 142 may be a semi-transmissive layer having a thickness of several tens of nanometers and transmitting a part of incident light and partially reflecting the light.

An adhesive layer 152 is applied on the second electrode 142 and a second substrate 150 is disposed on the adhesive layer 152 to attach the second substrate 150 to the display device. As the adhesive layer, any material may be used as long as it has good adhesion and heat and water resistance. In the present invention, a thermosetting resin such as an epoxy compound, an acrylate compound, or an acrylic rubber may be used. In this case, the adhesive layer 152 can be cured by irradiating the adhesive layer with light such as ultraviolet rays.

The adhesive layer 152 serves not only to bond the first substrate 110 and the second substrate 150, but also to act as an encapsulant for preventing moisture from penetrating into the EL display device. Therefore, although the term of reference numeral 162 is referred to as an adhesive in the detailed description of the present invention, this is for convenience, and the adhesive layer may also be referred to as an encapsulant.

The second substrate 150 is an encapsulation cap for encapsulating the electroluminescence display device and may be formed of a material such as a PS (polystyrene) film, a PE (polyethylene) film, a PEN (polyethylene naphthalate) A protective film may be used and glass may be used.

A protective layer may be disposed between the second electrode 142 and the adhesive layer 152. The protective layer may be composed of a single layer of an organic layer, a plurality of layers of an organic layer / an inorganic layer or an inorganic layer / an organic layer / an inorganic layer.

In the electroluminescent display device having the above-described structure, the first electrode 130 is formed of the reflective layer 132, the optical path control layer 134, and the transparent electrode 136, and a surface plasmon is generated between the metal electrode layer and the organic layer The light extraction efficiency of the light emitting display device can be improved.

The electroluminescent display device according to the present invention has a structure in which the thickness of the first electrode 130, that is, the thickness of the light path control layer 134 is set to a peak wavelength of R, G, B monochromatic light output from R, The width of the emission spectrum of the monochromatic light output during the constructive interference by the microcavity in the display element can be narrowed so that not only the light extraction efficiency can be improved but also light of a clear color can be output.

4 is a view showing an actual manufacturing method of an electroluminescence display device, and a method of manufacturing the electroluminescence display device according to the first embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 4, an inorganic material such as SiOx or SiNx is laminated on a first substrate 110 such as glass or plastic to form a buffer layer 112. The buffer layer 112 may be formed as a single layer or a plurality of layers. Then, an oxide semiconductor, crystalline silicon, or the like is stacked over the entire surface of the substrate 110 by the CVD method, and then the semiconductor layer 122 is formed on the buffer layer 112 by etching. The crystalline silicon layer may be formed by directly laminating crystalline silicon, or may be formed by laminating amorphous silicon and then crystallizing an amorphous material by various crystallization methods such as laser crystallization. The n ⁺ or p ⁺ -type impurity is doped on both sides of the crystalline silicate layer to form a doping layer.

Thereafter, an inorganic insulating material such as SiOx or SiNx is deposited on the semiconductor layer 122 by CVD (Chemical Vapor Deposition), and an inorganic insulating material such as Cr, Mo, Ta, Cu, Ti, Al, A gate insulating layer 123 and a gate electrode 125 are formed by simultaneously etching the inorganic insulating material and the metal. The gate insulating layer 123 may be formed over the entire surface of the first substrate 110 and only the gate electrode 125 may be etched.

 An inorganic insulating material is then deposited on the entire surface of the substrate 110 on which the gate electrode 125 is formed to form an interlayer insulating layer 114 and a part of the interlayer insulating layer 114 is etched to form a semiconductor Thereby forming first contact holes 114a through which both side surfaces of the layer 122 are exposed.

Thereafter, an opaque metal having good conductivity such as Cr, Mo, Ta, Cu, Ti, Al, or Al alloy is deposited on the first substrate 110 by sputtering and then etched to form a first contact hole A source electrode 127 and a drain electrode 128 electrically connected to the semiconductor layer 122 are formed through the first electrode layer 114a and the driving thin film transistor is disposed on the first substrate 110. [

4B, an organic insulating material such as photo-acryl is stacked over the entire surface of the first substrate 110 on which the source electrode 127 and the drain electrode 128 are disposed to form a protective layer 116 .

4C, a reflective layer 132 is formed on the protective layer 116 by laminating and etching a metal having a good reflectivity such as Al, Ag, Au, and then forming a reflective layer 132 such as SiOx or SiNx An inorganic material is laminated by a CVD method to form an optical path control layer 134. The light path control layer 134 is formed to have different thicknesses depending on the R, G, and B pixels. The passivation layer 116, the reflective layer 132 and the light path control layer 134 are etched to form a second contact hole 116a through which the drain electrode 128 of the thin film transistor is exposed.

Thereafter, a metal oxide such as ITO, IGZO, or IZO or a conductive polymer is stacked on the light path control layer 134 and etched to form a transparent contact hole electrically connected to the drain electrode 128 through the second contact hole 116a. Electrode 136 is formed.

As shown in FIG. 4D, a bank layer 138 is formed in the boundary region of the pixel P on the transparent electrode 136 to divide the pixel. The bank layer 138 may be formed first, and the transparent electrode 136 may be formed.

The reflective layer 132, the light path control layer 134, and the transparent electrode 136 may be formed in separate processes. The light path control layer 134 having different thicknesses may be formed by different processes for each of R, G, and B pixels, or may be formed by a single process using a halftone mask.

The reflective layer 132 may be formed as a film (in this case, the reflective layer may be a reflective plate or a reflective film). In this case, a film-shaped reflection plate may be attached on the first substrate 110 on which the thin film transistor is formed, and then the light control layer 134 and the transparent electrode 136 may be formed by a photolithography process.

A light emitting layer 140 is formed on the transparent electrode 136 and the bank layer 136. A metal such as Al, Ag, or Au is deposited on the light emitting layer 140 by sputtering to a thickness of several tens nm, Thereby forming the second electrode 142.

4E, an adhesive is applied to the second electrode 142 to form an adhesive layer 152, a second substrate 150 such as a glass or a film is placed on the adhesive layer 152, The adhesive layer 152 is cured to complete the electroluminescent display device.

As described above, the first electrode 130 of the electroluminescence display device according to the first embodiment of the present invention is formed of the reflection layer 132, the light path control layer 134, and the transparent electrode 136, It is possible to prevent the surface plasmon from being generated in the electroluminescence display device by the adjustment layer 134, thereby improving the light extraction efficiency.

The electroluminescent display device of the present invention improves the light extraction efficiency by controlling the length of the optical path of the microcavity by controlling the thickness of the optical path control layer 134 of the first electrode 130, It is possible to output enhanced monochromatic light.

Since the optical path of the micro cavity is formed between the reflective layer 132 of the first electrode 130 and the second electrode 140 which is translucent, by controlling the thickness of the layer other than the optical path control layer 134, The length of the optical path of the cavity can also be adjusted.

5 is a cross-sectional view briefly showing a structure of an electroluminescent display device according to a second embodiment of the present invention. In the drawings, R, G, and B pixels are shown for convenience of explanation.

Since the structure of the electroluminescent display device of this embodiment is different from the structure of the electroluminescent display device of the first embodiment shown in FIG. 1 in that the first electrode 230 is described, the first electrode 230 will be described, The description of the structure is omitted or simplified.

5, a light emitting device including a first electrode 230, a light emitting layer 240, and a second electrode 242 is disposed on a first substrate 210, and a second substrate 250 is disposed thereon. And the first substrate 210 and the second substrate 250 are bonded together by the adhesive layer 252.

The first electrode 230 is composed of reflective layers 232R, 232G and 232B, an optical path control layer 234 and a transparent electrode 236. The light path control layer 234 is disposed between the reflection layers 232R, 232G and 232B made of a metal and the transparent electrode 236 made of an organic material such as a metal oxide material or a conductive polymer to suppress the generation of surface plasmon So that the light extraction efficiency of the electroluminescence display device can be improved.

The second electrode 242 is formed between the reflective layer 232 of the first electrode 230 and the second electrode 242 because a metal such as Al, Au, or Ag is formed in a semitransparent state with a small thickness of several tens of nm. So that the light emitted from the light emitting layer 240 can interfere with the micro cavity to enhance the light extraction efficiency of the electroluminescence display device.

The reflective layer 232 of the first electrode 230 is formed with different thicknesses t1, t2 and t3 in the R, G and B pixels so that the optical path length L1 of the microcavity in the R, G and B pixels , L2, and L3 are formed differently. The wavelengths of the monochromatic light are determined according to the optical path lengths L1, L2 and L3 of the microcavities and the optical path lengths L1, L2 and L3 of the microcavities correspond to the thicknesses t1, t2 and t3 of the reflection layer 232, The wavelength of the monochromatic light is determined according to the thicknesses t1, t2 and t3 of the reflection layer 232. [

As described above, the electroluminescent display device according to the embodiment of the present invention adjusts the thicknesses t1, t2 and t3 of the reflective layer 232 so that the luminance of R, G, and B monochromatic light output from the R, The optical extraction efficiency can be improved by adjusting the optical path lengths (L1, L2, L3) of the microcavity to correspond to the peak wavelengths of the emitted monochromatic light, It is possible to output light of high purity by narrowing the width.

6 and 7 are views illustrating a structure of an electroluminescent display device according to a third embodiment of the present invention. An electroluminescent display device of this structure is a bottom emission display device that outputs light in a downward direction. Description of the same contents as those described in Figs. 1 and 2 will be omitted.

6 and 7, a semiconductor layer 322, a gate insulating layer 323, a gate electrode 325, and a source electrode (not shown) are formed on a buffer layer 312 of a first substrate 310 made of transparent glass or plastic 327 and a drain electrode 328, and a protective layer 316 is formed on the thin film transistor. The protective layer 316 may be composed of an organic layer or may be composed of a plurality of layers of an organic layer and an inorganic layer.

A second contact hole 316a through which the drain electrode 328 of the thin film transistor is exposed is formed in the passivation layer 316 and a first electrode 330 is formed on the second contact hole 316a. The first electrode 330 is electrically connected to the drain electrode 328. A bank 338 is formed in the boundary region of the pixel and a light emitting layer 332 is formed on the first electrode 330 and the bank layer 338.

The first electrode 330 is formed of a semitransparent metal layer formed of a metal such as Al, Ag, or Au to a thickness of several tens nm. The light emitting layer 332 includes a light emitting layer for emitting actual light as voltage is applied thereto, an electron injection layer and a hole injection layer for injecting electrons and holes respectively into the light emitting layer, an electron transport layer for transporting the injected electrons and holes to the light emitting layer, A hole transport layer and the like.

A second electrode 340 is disposed on the light emitting layer 332. The second electrode 334 includes a transparent electrode 342 disposed on the light emitting layer 332 to apply a voltage to the light emitting layer 332 and a light emitting layer 332 disposed on the transparent electrode 342, A reflection layer 346 that reflects the first transparent electrode 343 and forms a micro cavity together with the translucent first electrode 330 and a transparent conductive layer 346 disposed between the transparent electrode 342 and the reflective layer 346 to suppress the generation of surface plasmon in the device. And an optical path control layer 344 for adjusting the optical path length inside the micro cavity.

The transparent electrode 342 is formed of a metal oxide such as ITO, IGZO, or IZO or a conductive polymer. The reflective layer 346 is formed of a metal having high reflectance such as Al, Ag, or Au. The light path control layer 344 may be formed of an inorganic material such as SiOx or SiNx, but is not limited thereto.

The light path adjusting layer 344 or the reflection layer 346 of the R, G, and B pixels are formed to have different thicknesses so that the optical path lengths of the microcavity structures of the R, G, and B pixels are formed differently, The width of the spectrum of the light is minimized, and a clear image can be realized.

The electroluminescent display device of the present invention may be applied to various devices such as a mobile device, a video phone, a smart watch, a watch phone, a wearable device, a foldable device, a rollable device, device, a bendable device, a flexible device, a curved device, an electronic organizer, an electronic book, a portable multimedia player (PMP), a personal digital assistant (PDA) Medical devices, desktop PCs, laptop PCs, netbook computers, workstations, navigation, vehicle navigation, vehicle displays, televisions, wall paper displays, notebooks , A monitor, a camera, a camcorder, a home appliance, and the like.

The present invention can be described as follows.

An electroluminescent display device according to an embodiment of the present invention includes a first electrode and a second electrode disposed on a substrate, a light emitting layer disposed between the first electrode and the second electrode, and a light emitting layer disposed below the first electrode, And a light path control layer disposed between the first electrode and the reflective layer for suppressing the generation of surface plasmon at the interface between the first electrode and the reflective layer.

According to another aspect of the present invention, the first electrode may be composed of a metal oxide or a conductive polymer.

According to another aspect of the present invention, the second electrode may be composed of a metal layer.

According to another aspect of the present invention, the light path control layer may be composed of an inorganic material.

According to another aspect of the present invention, the reflective layer and the second electrode may form a microcavity.

According to another aspect of the present invention, the optical path length of the microcavity may vary depending on the thickness of the optical path control layer.

According to another aspect of the present invention, the substrate may include R, G, and B pixels, and the thickness of the optical path control layer formed in each of the R, G, and B pixels may be a thickness of the monochromatic light corresponding to R, G, Can be adjusted according to the wavelength.

An electroluminescent display according to an embodiment of the present invention includes a substrate including R, G, and B pixels, and a light emitting layer formed on the substrate, the first electrode, the second electrode, Emitting layer, and the light path lengths of the micro-cavity structures of the R, G, and B pixels are different from each other, and the optical path length is adjusted according to the thickness of the first electrode.

According to another aspect of the present invention, the first electrode may include a reflective layer that reflects light incident from the light emitting layer, a transparent electrode that applies a voltage to the light emitting layer, and an optical path control layer disposed between the reflective layer and the transparent electrode .

According to another aspect of the present invention, the optical path length of the micro cavity structure may vary depending on the thickness of the optical path control layer.

According to another aspect of the present invention, the optical path length of the micro cavity structure may be varied depending on the thickness of the optical path control layer corresponding to the wavelength of the monochromatic light of the R, G, and B pixels.

According to another aspect of the present invention, the optical path length of the microcavity structure may vary depending on the thickness of the reflective layer.

While a great many are described in the foregoing description, it should be construed as an example of preferred embodiments rather than limiting the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

122: semiconductor layer 125: gate electrode
127: source electrode 128: drain electrode
130: first electrode 132: reflective layer
134: light path control layer 136: transparent electrode
140: light emitting layer 142: second electrode

Claims (12)

A first electrode and a second electrode disposed on the substrate;
A light emitting layer disposed between the first electrode and the second electrode;
A reflective layer disposed under the first electrode and reflecting light incident from the light emitting layer; And
And an optical path control layer disposed between the first electrode and the reflective layer and suppressing generation of surface plasmon at an interface between the first electrode and the reflective layer. The electroluminescent display of claim 1, wherein the first electrode comprises a metal oxide or a conductive polymer. The electroluminescent display of claim 1, wherein the second electrode comprises a metal layer. The electroluminescent display device of claim 1, wherein the light path control layer is made of an inorganic material. The electroluminescent display of claim 1, wherein the reflective layer and the second electrode form a microcavity. 6. The electroluminescent display device according to claim 5, wherein an optical path length of the microcavity varies depending on a thickness of the optical path control layer. The organic light emitting display according to claim 1, wherein the substrate includes R, G, and B pixels, and the thickness of the light path control layer formed in each of the R, G, and B pixels is a thickness of the monochromatic light corresponding to the R, An electroluminescent display device adjusted according to wavelength. A substrate including R, G, and B pixels; And
And a light emitting element formed on the substrate and including a first electrode, a second electrode, and a light emitting layer disposed between the first electrode and the second electrode,
Wherein the optical path lengths of the micro cavity structures of the R, G, and B pixels are different from each other, and the optical path length is adjusted according to the thickness of the first electrode. The plasma display panel of claim 8,
A reflective layer for reflecting light incident from the light emitting layer;
A transparent electrode for applying a voltage to the light emitting layer; And
And an optical path adjusting layer disposed between the reflective layer and the transparent electrode. The electroluminescent display of claim 9, wherein the optical path length of the microcavity structure is varied depending on the thickness of the optical path control layer. The electroluminescent display of claim 10, wherein an optical path length of the microcavity structure is varied depending on a thickness of the light path control layer corresponding to a wavelength of the monochromatic light of the R, G, and B pixels. The electroluminescent display device of claim 9, wherein an optical path length of the microcavity structure varies depending on a thickness of the reflective layer.

Images