KR102154489B1 - Organic Electro-Luminescence Device - Google Patents

Abstract

The present invention discloses an organic electroluminescent device. The disclosed organic light emitting diode device includes: a substrate in which a plurality of red (R), green (G), blue (B), and white (W) pixel regions are partitioned; Driving thin film transistors and red (R), green (G), blue (B), and white (W) color filters formed in pixel regions on the substrate; An organic light emitting diode connected to the driving thin film transistor formed in each of the pixel regions and disposed on the red (R), green (G), blue (B), and white (W) color filters; And a low-reflective layer disposed between the substrate and the organic light emitting diode in at least one of the red (R), green (G), blue (B), and white (W) pixel regions.

Description

Organic Electro-Luminescence Device

The present invention relates to an organic electroluminescent device.

Until recently, CRT (cathode ray tube) was mainly used as a display device. However, recently, flat panels such as plasma display panels (PDP), liquid crystal display devices (LCDs), organic electro-luminescence devices (OLEDs) that can replace CRTs Display devices are widely studied and used.

Among the flat panel display devices as described above, the organic light emitting device (hereinafter referred to as OLED) is a self-luminous device, and since it does not require a backlight used in a liquid crystal display device that is a non-light emitting device, it is possible to have a lightweight and thin type.

In addition, the viewing angle and contrast ratio are excellent compared to the liquid crystal display device, and it is advantageous in terms of power consumption, DC low voltage driving is possible, the response speed is fast, and the internal components are solid, so it is strong against external shocks and the operating temperature range is also wide. Have.

In particular, since the manufacturing process is simple, there is an advantage that the production cost can be reduced more than that of the existing liquid crystal display device. OLEDs with such characteristics are largely divided into a passive matrix type and an active matrix type. In the passive matrix type, devices are formed in a matrix form crossing signal lines, whereas the active matrix type is a pixel A thin film transistor, which is a switching element that turns on/off, and a driving thin film transistor that passes current and a capacitor that maintains voltage for one frame in the driving thin film transistor are positioned for each pixel.

In addition, in the OLED, an organic light emitting diode is formed for each pixel. The organic light emitting diode includes an anode, a cathode, and an organic light emitting layer.

In the organic light emitting diode, when a voltage is applied between an anode and the cathode, holes are injected from the anode into the organic emission layer, and electrons are injected from the cathode into the organic emission layer. Holes and electrons injected into the organic emission layer combine in the organic emission layer to generate excitons, and the excitons transition from an excited state to a ground state to emit light.

Recently, the passive matrix type has many limiting factors such as resolution, power consumption, and lifespan, and thus active matrix type OLEDs capable of realizing a high resolution or a large screen are actively being studied.

In particular, in order to improve the screen quality of OLEDs, a technology has been developed to prevent external light from being reflected in the substrate area or totally reflected inside the substrate by attaching a polarizing plate on the substrate.

However, the technology of attaching a polarizing plate on the entire surface of the OLED substrate has the effect of absorbing external light and reducing the reflectance, but the light generated from the organic light emitting layer of the organic light emitting diode is absorbed to the outside of the substrate, reducing the luminous efficiency. there is a problem.

In the present invention, a low-reflective film is formed for each red (R), green (G), blue (B) and white (W) pixel or only white (W) pixels of an organic light emitting diode, thereby lowering the contrast ratio due to external light. The purpose is to provide an organic electroluminescent device that prevents

In addition, an object of the present invention is to provide an organic light-emitting device that prevents luminance defects in a white (W) pixel area when a black mode is implemented by forming a low-reflection film on a white (W) pixel of an organic light-emitting device. .

The organic electroluminescent device of the present invention for solving the problems of the prior art as described above includes a substrate in which a plurality of red (R), green (G), blue (B) and white (W) pixel regions are partitioned; Driving thin film transistors and red (R), green (G), blue (B), and white (W) color filters formed in pixel regions on the substrate; An organic light emitting diode connected to the driving thin film transistor formed in each of the pixel regions and disposed on the red (R), green (G), blue (B), and white (W) color filters; And a low-reflective layer disposed between the substrate and the organic light emitting diode in at least one of the red (R), green (G), blue (B), and white (W) pixel regions.

In addition, the organic light emitting diode of the present invention includes: a first substrate in which a plurality of red (R), green (G), blue (B), and white (W) pixel regions are partitioned; A driving thin film transistor and an organic light emitting diode formed in pixel regions on the first substrate; A capping layer formed on the driving thin film transistor and the organic light emitting diode; A second substrate facing the first substrate; Red (R), green (G), blue (B) and white formed on the second substrate to correspond to the plurality of red (R), green (G), blue (B) and white (W) pixel regions (W) color filters; And a low-reflective layer disposed between the capping layer of the first substrate and the second substrate in at least one of the red (R), green (G), blue (B), and white (W) pixel regions. Includes.

The organic electroluminescent device of the present invention forms a low-reflective film for each of red (R), green (G), blue (B) and white (W) pixels or only white (W) pixels of the organic electroluminescent device, There is an effect of preventing a decrease in the contrast ratio due to.

In addition, the organic light emitting diode of the present invention has an effect of preventing luminance defects in the white (W) pixel region when implementing the black mode by forming a low-reflective layer on the white (W) pixel of the organic light emitting device.

1 is a cross-sectional view showing the structure of an OLED according to a first embodiment of the present invention.
2 is a diagram showing a pixel structure of an OLED according to a first embodiment of the present invention.
3A and 3B are graphs showing the refractive index and extinction coefficient of the metal used in the low-reflective film of the first embodiment of the present invention.
4A to 6B are diagrams comparing a comparative example and an example of the present invention when driving black OLED.
7 is a view showing the light efficiency characteristics of the OLED according to the first embodiment of the present invention.
8A is a cross-sectional view showing the structure of an OLED according to a second embodiment of the present invention.
8B is a diagram schematically illustrating a structure of a white (W) pixel area of FIG. 8A.
9A is a cross-sectional view showing the structure of an OLED according to a third embodiment of the present invention.
9B is a diagram schematically illustrating a structure of a white (W) pixel area of FIG. 9A.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms different from each other, and only these embodiments make the disclosure of the present invention complete, and common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have it, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are exemplary, and the present invention is not limited to the illustrated matters. The same reference numerals refer to the same components throughout the specification. In addition, in describing the present invention, when it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

When'include','have','consists of' and the like mentioned in the present specification are used, other parts may be added unless'only' is used. In the case of expressing the constituent elements in the singular, it includes the case of including the plural unless specifically stated otherwise.

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

In the case of a description of the positional relationship, for example, if the positional relationship of two parts is described as'upper','upper of','lower of','next to','right' Or, unless'direct' is used, one or more other parts may be located between the two parts.

In the case of a description of a temporal relationship, for example,'after','following','after','before', etc. It may also include cases that are not continuous unless' is used.

First, second, etc. are used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one component from another component. Accordingly, the first component mentioned below may be a second component within the technical idea of the present invention.

Each of the features of the various embodiments of the present invention can be partially or entirely combined or combined with each other, technically various interlocking and driving are possible, and each of the embodiments can be implemented independently of each other or can 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. In addition, in the drawings, the size and thickness of the device may be exaggerated for convenience. The same reference numbers throughout the specification denote the same elements.

On the other hand, the OLED 100 is divided into a top emission type and a bottom emission type according to the transmission direction of the emitted light. Hereinafter, the first and second embodiments of the present invention are provided with a bottom emission type. As an example, the third embodiment of the present invention will be described with a top emission method in FIG. 9 as an example.

1 is a cross-sectional view showing the structure of an OLED according to a first embodiment of the present invention.

Referring to FIG. 1, in the OLED 100 according to the first embodiment of the present invention, a driving region DA and a bank 221 are formed in a region in which a driving thin film transistor 210 (DTr) is formed for convenience of description. The non-pixel area (NA), red (R), green (G), blue (B), and white (W) color filters 223a, 223b, 223c, and 223d are formed as a light emitting area. It is defined as (PA). In addition, the white (W) color filter 223d does not have a separate color filter pattern, but for convenience of explanation, the transparent organic layer 120 formed in the white (W) pixel region is used as a white (W) color filter 223d. ).

In the first embodiment of the present invention, a low-reflective film 250 is formed in an area corresponding to the area where the white (W) color filter 223d is formed, so that external light is reflected from the area of the substrate 101 to cause luminance defects. Was prevented. In addition, the low-reflective film 250 proceeds to the inside of the white (W) color filter 223d and the organic light emitting diode (E) region through the substrate 101, and is reflected from the reflective electrode (the second electrode 232) to provide luminance. Problems causing defects can be prevented.

As shown in Fig. 1, the lower light emitting type OLED 100 according to the present invention includes a driving thin film transistor 210 (DTr), a switching thin film transistor (not shown), and a substrate 101 on which an organic light emitting diode E is formed. , And a capping layer 140 that faces the substrate 101 and is formed for encapsulation. The capping layer 140 may be a flexible substrate such as plastic or a metal substrate.

In addition, the substrate 10 is a transparent flexible substrate, and may be glass or plastic, but is not limited thereto.

Further, although not shown in the drawings, a moisture absorbent for removing moisture penetrating from the outside may be formed on the inner surface of the capping layer 140.

In the non-pixel region (NA) of the substrate 101, a driving thin film composed of a gate electrode 201, a gate insulating layer 102, a channel layer 204, source and drain electrodes 207a and 207b, and an etch stopper 205 A transistor 210 (DTr) is formed, and in the light emitting area PA, the gate insulating film 102, the protective film 109 and the red (R), green (G), blue (B) and white are on the substrate 101. (W) Color filters 223a, 223b, 223c, and 223d are formed.

In addition, the channel layer 204 of the driving thin film transistor 210 is an oxide semiconductor containing at least one of indium (In), zinc (Zn), gallium (Ga), or hafnium (Hf) in order to implement high-speed response characteristics. Can be formed as

In addition, although not shown in the drawing, between the gate electrode 201 of the driving thin film transistor 210 (DTr) and the substrate 101, a buffer layer composed of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or multiple layers thereof is formed on the substrate 101. ) Can be formed more on the front.

As described above, the driving thin film transistor 210 and the red (R), green (G), and blue (B) color filters 223a on the substrate 101 of the non-pixel region NA and the emission region PA, When 223b and 223c and the low-reflective layer 250 are formed, an organic layer 120 is formed on the entire surface of the substrate 101. In the white (W) pixel area, the transparent organic layer 120 serves as the white (W) color filter 223d without a separate color filter.

The organic layer 120 serves as an overcoat layer capable of alleviating a lower step, and may be a benzocyclobutene (BCB) layer, a polyimide layer, or a polyacrylic layer.

In addition, a bank layer 221 is patterned in the non-pixel area NA to partition each pixel area on the organic layer 120, and a first electrode is formed on the organic layer 120 corresponding to the emission area PA. (230: anode), the organic light emitting layer 231, and the organic light emitting diode (E) consisting of the second electrode (232: Cathode) is formed.

The first electrode 230 may be an anode electrode, and is formed by stacking at least one of transparent conductive materials such as Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), and Indium Tin Zinc Oxide (ITZO). can do. In addition, the first electrode 230 is electrically connected to the drain electrode 207b of the driving thin film transistor 210 by a contact hole formed in the organic layer 120.

The organic light emitting layer 231 is a hole injection layer (HIL), a hole transporting layer (HTL), an emitting layer (EML: Emitting Material Layer), an electron transporting layer (ETL), and an electron injection layer. (EIL: Electron Injection Layer) can be included. The hole transport layer may further include an electron blocking layer (EBL), and the electron transport layer (ETL) may be formed using a low molecular weight material such as PBD, TAZ, Alq3, BAlq, TPBI, and Bepp2. .

Since the color of the organic emission layer 231 is different depending on the organic material, red (R), green (G), and blue (B) emission layers are formed for each pixel area to implement full color or , It can be implemented as a white light emitting layer. In the exemplary embodiment of the present invention, a description will be made focusing on the case of the white organic emission layer 231 that generates white light.

The second electrode 232 may be a cathode electrode, and may be formed of a metal film such as aluminum (Al) or silver (Ag) having high reflectivity.

As described above, when the organic light emitting diode E is formed on the substrate 101, a capping layer 140 for encapsulation is formed on the entire surface of the substrate 101.

In the present invention, external light is absorbed by the low-reflective film 250 formed in the substrate 101 region, thereby reducing the amount of reflected light reflected in the substrate 101 region, thereby causing poor luminance in the white (W) region when driving black. Prevent.

In the drawing, the low-reflective layer is formed between the organic layer 120 and the protective layer 109 used as an overcoat layer, but is not limited thereto. Accordingly, in some cases, the low-reflective layer 250 may be formed between the substrate 101 and the gate insulating layer 102, and between the gate insulating layer 102 and the protective layer 109.

It is preferable that the low-reflective layer 250 is formed of a metal having a refractive index (n) and an extinction coefficient (k) similar to each other. For example, chromium (Cr) or molybdenum (Mo) may be used. However, since it is not limited thereto, metal materials such as aluminum (Al), silver (Ag), titanium (Ti), tantalum (Ta), tungsten (W), and copper (Cu) may be used.

In addition, although the first embodiment of the present invention has been described focusing on the formation of the low-reflective layer 250 only in the white (W) pixel region, the present invention is not limited thereto. Accordingly, a low-reflective layer can be formed in all of the red (R), green (G), and blue (B) pixel regions. When a low-reflective layer is formed in the red (R), green (G), and blue (B) pixel areas, the red (R), green (G), and blue (B) color filters 223a, 223b, 223c are centered. It can be formed on the lower side or the upper side.

That is, the first electrode 230 and the red (R), green (G), and blue (B) color filters 223a, 223b and 223c are centered on the red (R), green (G), and blue (B) color filters 223a, 223b, and 223c. ) A low-reflective layer may be formed between the color filters 223a, 223b, and 223c or between the red (R), green (G), and blue (B) color filters 223a, 223b, 223c and the substrate 101 have.

The organic electroluminescent device of the present invention forms a low-reflective film for each of red (R), green (G), blue (B) and white (W) pixels or only white (W) pixels of the organic electroluminescent device, There is an effect of preventing a decrease in the contrast ratio due to.

2 is a diagram showing a pixel structure of an OLED according to a first embodiment of the present invention, and FIGS. 3A and 3B are graphs showing the refractive index and extinction coefficient of the metal used for the low-reflective film of the first embodiment of the present invention. .

Referring to FIG. 2 along with FIG. 1, the substrate 101 of the OLED is divided into red (R), green (G), blue (B) and white (W) regions, and an organic film ( A low-reflective film 250 is formed between the 120 and the substrate 101.

Referring to FIGS. 3A and 3B, it is preferable that the low-reflective layer 250 formed in the embodiment of the present invention has excellent light absorption and can transmit light generated from the organic light emitting layer without loss of light.

First, since a metal having a large light absorptivity has a refractive index (n) and an extinction coefficient (k) that are similar to each other, a metal having an n/k value of 1 or less is suitable for use as the low-reflective film 250. Therefore, metals having a refractive index (n) and extinction coefficient (k) ratio (n/k) of 0.3 to 1.2 are used as the low-reflective film.

In addition, since a metal having a high light absorption rate has a relatively low light transmittance, in order to use a metal having a high light absorption rate as a low-reflective film, it is desirable to secure the transmittance by forming it thinly in angstroms (Å).

In general, in embodiments of the present invention, the thickness of the low-reflective layer 250 may be selectively formed in the range of 10 to 200Å.

Looking at the graphs of the refractive index and extinction coefficient of FIGS. 3A and 3B, it can be seen that the refractive index and extinction coefficient of chromium (Cr: n/k=1.01) or molybdenum (Mo: n/k=0.35) are similar to each other.

Therefore, since a metal having a similar refractive index (n) and extinction coefficient (k) has a high light absorption rate, chromium (Cr) or molybdenum (Mo) has a high light absorption rate in the visible light region. Accordingly, reflection of external light may be lowered and luminous efficiency of the organic light emitting layer may be increased.

However, since metals generally absorb light, when the thickness to be formed is adjusted, not only chromium (Cr) or molybdenum (Mo) but also other opaque metals may be used. For example, any material capable of a sputtering process and an etching process may be used as a low-reflective layer.

In addition, when the refractive index (n) value of a metallic material increases, the transmittance increases, the wavelength of light decreases, and when the extinction coefficient (k) value increases, the light absorption rate increases. Therefore, the refractive index (n) and extinction coefficient (k) values All of these have large values, and if the ratio (n/k) is close to 1, the transmittance of internal light generated from the organic light emitting layer can be increased while increasing the external light absorption rate.

As mentioned above, when a metal with a large extinction coefficient (k) value and a small refractive index (n) value is used as a low-reflective film, the external light absorption rate is excellent, while the internal light transmittance is low, so the physical thickness is reduced. By adjusting, the transmittance can be secured.

In addition, the low-reflective film 250 used in the exemplary embodiment of the present invention can be used for micro-cavity optical design.

Σ{nx*(dx/λb)}+Σ{nE*(dE/λb)}+Σ{ny*(dy/λb)}=1.85~3.15......(Equation 1)

(n is the refractive index, x is the inorganic material, d is the thickness, E is the first electrode, y is the organic emission layer, λb is the blue peak wavelength, and 1.85-3.15 is the point where the wavelength is twice the wavelength (reinforced interference))

That is, by adjusting the thickness of the inorganic material used as the low-reflective layer, the first electrode, and the organic light-emitting layer based on the organic light-emitting diode generating blue wavelength light, it is possible to design a micro-cavity optical design that can increase light efficiency.

Here, if the transmittance before the organic light-emitting diode is formed satisfies the requirement of 80% or more, and the thickness of layers formed by inorganic materials such as metal is fixed, the optimum microcirculation is achieved by adjusting the thickness of organic materials such as organic light-emitting layers. Cavity optical design can be done.

As shown in FIG. 2, in the white (W) region, the organic layer 120 serves as a white (W) color filter without a separate color filter pattern. Accordingly, when external light is incident through the substrate 101, the light that has passed through the substrate 101 region and the substrate 101 is reflected by the second electrode 232 of the organic light emitting diode E, and light is emitted.

This reflected light appears in a gray form by the reflected light when the black luminance is implemented, which causes the screen quality to deteriorate.

However, in the exemplary embodiment of the present invention, since the low-reflective film 250 having a high light absorption rate is formed between the substrate 101 and the organic film 120, the amount of light reflected from the substrate 101 area can be reduced.

In addition, since the light that has passed through the low-reflective layer 250 is reflected by the second electrode 232 of the organic light-emitting diode E and then is absorbed by the low-reflective layer 250 again, the generation of luminance due to the secondary reflected light is prevented. Can be reduced.

4A to 6B are diagrams comparing a comparative example and an example of the present invention when the OLED is driven in black.

Referring to FIGS. 4A and 4B, as in Comparative Example 1, a polarizing plate was disposed to reduce reflected light generated in a substrate region by external light.

That is, a first electrode, an organic light emitting layer, a second electrode, and a capping layer are formed on one surface of the substrate, and a polarizing plate is attached to the entire area of the other surface of the substrate to absorb external light.

In Comparative Example 1, since most of the light incident from the outside is absorbed by the polarizing plate, there is an advantage of reducing reflected light generated in the substrate region.

However, since the polarizing plate also absorbs light generated from the organic light-emitting layer, the luminous efficiency of the organic light-emitting diode is reduced.

As shown in FIG. 4B, when black driving is performed on the OLED of Comparative Example 1, it can be seen that when the black luminance is realized, the reflected light is small and high-quality black color is implemented. However, light generated for image display in the organic light-emitting layer is also absorbed by the polarizing plate, thereby reducing light efficiency.

5A and 5B, as mentioned in FIGS. 4A and 4B, when a polarizing plate is attached to the substrate of the organic light emitting diode, reflected light generated from the substrate can be reduced, but the luminous efficiency of the organic light emitting diode Since this was low, the polarizing plate was removed.

Accordingly, in Comparative Example 2, the luminous efficiency of the organic light emitting diode is improved, but the reflected light generated from the substrate or the second electrode of the organic light emitting diode cannot be removed by external light.

As shown in FIG. 5B, when black driving is performed on the OLED of Comparative Example 2, it can be seen that gray color is realized by reflected light when black luminance is realized. That is, light loss generated by the organic light emitting diode can be minimized, but when the black luminance is realized, the contrast ratio is lowered by the reflected light.

Referring to FIGS. 6A and 6B, when a low-reflective film is formed on one surface of a substrate, as in the exemplary embodiment of the present invention, since external light is absorbed in the substrate region, the amount of reflected light in the substrate region can be reduced.

As shown in FIG. 6B, it can be seen that when the black luminance is implemented, a gum-violet color is displayed. That is, it can be seen that a black color corresponding to Comparative Example 1 in which the polarizing plate is attached to the substrate and Comparative Example 2 in which the polarizing plate is completely removed is realized.

7 is a view showing the light efficiency characteristics of the OLED according to the first embodiment of the present invention.

Referring to FIG. 7, in Comparative Examples 1 and 2 of FIGS. 4A and 5A and the first embodiment of the present invention, the thickness of the low-reflective film is set to 60Å (Example 1(a)) and the thickness of the low-reflective film is set to 100Å. The light efficiency characteristics in the case of (Example 1(b)) were compared.

In addition, Example 1(a) and Example 1(b) are in which low-reflective films are formed in all of the red (R), green (G), blue (B) and white (W) pixel regions of the organic light emitting device. This is the case.

Comparative Example 1 is a case in which a polarizing plate for absorbing light is disposed on the back of the substrate of the organic light emitting device, and at this time, the light efficiency (Cd) in the red (R), green (G), blue (B) and white (W) pixel regions /A) was set to 100.

As described in FIGS. 4A and 4B, in Comparative Example 1, although the polarizing plate has an effect of reducing the reflectance of external light, there is a problem of lowering the luminous efficiency of the organic light emitting diode.

In Comparative Example 2, the polarizing plate attached to the substrate of the organic light emitting diode was removed to improve the luminous efficiency. Compared to Comparative Example 1, the red (R), green (G), blue (B), and white (W) pixel regions It can be seen that the light efficiency increases to 238%, 238%, 231%, and 237% respectively.

As in Example 1 (a) of the present invention, when the thickness of the low-reflective film formed on the organic light emitting device is 60Å, red (R), green (G), blue (B), and white (W) pixels It can be seen that the regions have light efficiencies of 212%, 212%, 144%, and 201%, respectively.

In addition, as in Example 1(b) of the present invention, when the thickness of the low-reflective film formed on the organic light emitting device is 100Å, red (R), green (G), blue (B), and white (W ) It can be seen that the pixel area has light efficiency of 183%, 165%, 131%, and 158%, respectively.

That is, as in the embodiment of the present invention, a low-reflective film having a high light absorption rate is used, but if the thickness is formed in the range of 10 to 200Å, the light efficiency characteristics can be greatly improved while reducing reflected light compared to Comparative Example 1 with a polarizer attached. It can have an effect.

FIG. 8A is a cross-sectional view showing a structure of an OLED according to a second embodiment of the present invention, and FIG. 8B is a diagram schematically showing the structure of a white (W) pixel area of FIG. 8A.

Hereinafter, the same reference numerals as those in FIG. 1 denote the same components, and description will be made centering on parts distinguished from the first embodiment of the present invention.

8A and 8B, the organic light emitting device 200 of the second embodiment according to the present invention includes a gate electrode 201, a gate insulating layer 102, and a channel in the non-pixel area NA of the substrate 101. A driving thin film transistor 210 comprising a layer 204, source and drain electrodes 207a and 207b, and an etch stopper 205 is disposed, and a gate insulating film 102 on the substrate 101 in the light emitting region PA, The passivation layer 109 and red (R), green (G), blue (B) and white (W) color filters 223a, 223b, 223c, and 223d are formed, respectively.

In addition, on the organic layer 120 above the red (R), green (G), blue (B) and white (W) color filters 223a, 223b, 223c, 223d, an organic light emitting diode for each pixel area (E) is formed.

A first low-reflection film 251 is formed between the passivation film 109 and the organic film 120 in the white (W) color filter 223d of the second embodiment of the present invention, and the first low-reflection film 251 A second low-reflective layer 350 is formed between the organic layer 120 and the first electrode 230 corresponding to.

The first low-reflective film 251 and the second low-reflective film 350 may be formed of the metal described in the first embodiment of the present invention, and are formed on each of the first and second low-reflective films 251 and 350. Different metals can be used.

In addition, the thicknesses of the first and second low-reflective films 251 and 350 may be selectively formed from 10 to 200Å, and the first and second low-reflective films 251 and 350 may have different thicknesses. have.

In addition, although the first low-reflective layer 251 is formed on the protective layer 120 in the drawing, it is not limited thereto. Accordingly, in some cases, the first low-reflection layer 251 may be formed between the substrate 101 and the gate insulating layer 102, and between the gate insulating layer 102 and the protective layer 109.

In addition, the second low-reflective layer 350 is formed between the first electrode 230 and the organic layer 120, but is not limited thereto. Accordingly, in some cases, the second low-reflective layer 350 may be formed between the gate insulating layer 102 and the protective layer 109 or between the protective layer 109 and the organic layer 120. In this case, the position of the first low-reflective film 251 is formed under the second low-reflective film 350.

For example, when the second low-reflective film 350 is formed between the gate insulating film 102 and the protective film 109, the first low-reflective film 251 is formed between the gate insulating film 102 and the substrate 101, When the second low-reflective layer 350 is formed between the protective layer 109 and the organic layer 120, the first low-reflective layer 251 is formed between the gate insulating layer 102 and the protective layer 109.

In addition, in the OLED 200 of FIG. 8A, the first and second low-reflective films 251 and 350 have been described mainly in the white (W) pixel region, but as in the first embodiment of the present invention, the first And the second low-reflective layers 251 and 350 may also be formed in red (R), green (G), and blue (B) pixel regions.

Referring to FIG. 8B, a first low reflection film is formed between the substrate and the organic film, and a second low reflection film is formed between the organic film and the first electrode of the organic light emitting diode.

In the second embodiment of the present invention, external light is sequentially absorbed by the first and second low-reflective layers, so that the amount of reflected light generated in the substrate region and the lower region of the organic light emitting diode can be reduced.

In addition, external light travels to the organic light-emitting diode region, and light reflected from the second electrode of the organic light-emitting diode is also absorbed by the first and second low-reflective layers, so that a high-quality black color can be realized when driving black.

9A is a cross-sectional view showing a structure of an OLED according to a third exemplary embodiment of the present invention, and FIG. 9B is a schematic view showing the structure of a white (W) pixel area of FIG. 9A.

In the third embodiment of the present invention, a top emission type organic electroluminescent device will be described as an example. In addition, in the third embodiment of the present invention, the reference numerals are different from those of the first and second embodiments of the present invention, but the same construction as the first and second embodiments of the present invention may be formed of the same material and structure.

For example, in the third embodiment of the present invention, a low-reflective film is formed on the capping layer 540, and the reference numeral 560 is used. , It can be implemented in the same manner as the low-reflective film described in the second embodiment.

9A and 9B, the OLED 300 according to the third embodiment of the present invention includes a driving area DA and a bank 321 in an area in which a driving thin film transistor DTr is formed for convenience of description. The formed region is defined as a non-pixel region NA, and a pixel region in which light is generated by the organic light emitting diode E is defined as an emission region PA, respectively.

As shown, the top emission type organic light emitting device 300 according to the present invention includes a driving thin film transistor (DTr), a switching thin film transistor (DTr, not shown), and a first substrate 401 on which an organic light emitting diode (E) is formed. ), and a color filter substrate bonded while facing the first substrate 401.

A capping layer 540 for encapsulating the driving transistor DTr and the organic light emitting diode E is formed on the first substrate 401. In addition, the first substrate 401 may be a flexible substrate such as plastic or a metal substrate.

The color filter substrate includes a second substrate 400 made of a transparent flexible substrate or a metal substrate, such as a first substrate 401, and an organic light emitting diode of the first substrate 401 on the second substrate 400. Red (R), green (G), blue (B), and white (W) color filters 411a, 411b, 411c, 411d, and a flat layer 450 are included to correspond to E).

In the white (W) color filter 411d, a separate color filter pattern is not formed, and the transparent flat layer 450 is used as the white (W) color filter 411d.

In the non-pixel region NA of the first substrate 401, a gate electrode 301, a gate insulating film 402, a channel layer 304, source and drain electrodes 307a and 307b, and an etch stopper 305 are formed. A driving thin film transistor 310 (DTr) is formed, and a gate insulating layer 402, a protective layer 409, and an organic layer 420 are formed on the first substrate 401 in the emission area PA.

The organic layer 420 is formed on the entire area of the first substrate 401 including the non-pixel area NA and the emission area PA, and on the organic layer 420 corresponding to the emission area PA, FIG. 1 As described above, the organic light emitting diode E is formed including the first electrode 330, the organic light emitting layer 331, and the second electrode 332.

However, in the third embodiment of the present invention, it relates to a top emission type OLED, and the first electrode 330 is a first transparent electrode 330a, a reflective electrode 330b, and a second transparent electrode, as shown in FIG. 9B. (330c). Further, the second electrode 332 is also an opaque metal in the first embodiment of the present invention, but in the third embodiment of the present invention, a metal made of a transparent conductive material like the first electrode in the first embodiment is used.

In addition, the organic light emitting diode (E) is separated by red (R), green (G), blue (B), and white (W) pixel regions by the bank layer 321 formed on the non-pixel region NA. Is formed.

In addition, the channel layer 304 of the driving thin film transistor 310 is an oxide semiconductor containing at least one of indium (In), zinc (Zn), gallium (Ga), or hafnium (Hf) in order to implement high-speed response characteristics. Can be formed as

In addition, although not shown in the drawing, before forming the gate electrode 301 of the driving thin film transistor 310 (DTr) on the first substrate 401, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a multilayer thereof is used. The configured buffer layer may be further formed on the entire surface of the first substrate 401.

As described above, when the driving thin film transistor 310 and the organic light emitting diode E are formed on the first substrate 401 of the non-pixel region NA and the light emitting region PA, the front surface of the first substrate 401 A capping layer 540 is formed on.

In addition, a low-reflective layer 560 is formed on the capping layer 540 of the first substrate 401 corresponding to the white (W) color filter 411d formed on the second substrate.

In the third embodiment of the present invention, since it is a top emission type organic electroluminescent device, external light is incident through the rear surface of the second substrate 400 of the color filter substrate, and the incident light is transmitted to the white (W) color filter 411d. The amount of reflected light can be reduced by being absorbed by the corresponding low-reflective layer 560.

Accordingly, even in the third embodiment of the present invention, it is possible to prevent luminance defects in the white (W) region when driving black.

As described in the first embodiment of the present invention, it is preferable that the low-reflective layer 560 uses a metal having a refractive index n and an extinction coefficient k having similar values.

For example, chromium (Cr) or molybdenum (Mo) may be used. However, since it is not limited thereto, metal materials such as aluminum (Al), silver (Ag), titanium (Ti), tantalum (Ta), tungsten (W), and copper (Cu) may be used.

In addition, the low-reflective layer 560 may be formed between the second substrate 400 and the white (W) color filter 411d, or may be formed on the flat layer 450.

In addition, in the drawings, the low-reflective film 560 is formed in the white (W) pixel area of the OLED 300, but the low-reflective film 560 has red (R), green (G), and blue (B ) All may be formed in the pixel areas.

That is, the first substrate corresponding to the red (R), green (G), blue (B) and white (W) color filters 411a, 411b, 411c, 411d formed on the second substrate 400, respectively ( It may be formed on the capping layer 540 of 401).

In addition, the low-reflective layer 560 is between the second substrate 400 and the red (R), green (G), blue (B), and white (W) color filters 411a, 411b, 411c, 411d, or It may be formed on the flat layer 450 corresponding to the red (R), green (G), blue (B), and white (W) color filters 411a, 411b, 411c, and 411d.

Referring to FIG. 9B, in a third embodiment of the present invention, an organic light emitting diode E comprising a first electrode 330, an organic emission layer 331, and a second electrode 332 on a first substrate 401 Is disposed, and a capping layer 540, a low-reflective layer 560, and a second substrate 400 on which a white (W) color filter is formed are sequentially stacked on the organic light emitting diode E.

Accordingly, when external light is incident through the rear surface of the second substrate 400, it is absorbed by the low-reflective layer 560, and the amount of reflected light in the area of the second substrate 400 can be reduced.

100: OLED 101: substrate
102: gate insulating film 109: protective film
120: organic layer 221: bank layer
140: capping layer 201: gate electrode
204: channel layer E: organic light emitting diode

Claims (15)

A substrate in which a plurality of red (R), green (G), blue (B), and white (W) pixel regions are partitioned;
Driving thin film transistors and red (R), green (G), blue (B), and white (W) color filters formed in pixel regions on the substrate;
An organic light emitting diode connected to the driving thin film transistor formed in each of the pixel regions and disposed on the red (R), green (G), blue (B), and white (W) color filters; And
A low-reflective layer disposed between the substrate and the organic light emitting diode in at least one of the red (R), green (G), blue (B) and white (W) pixel areas,
The low-reflective layer is a material having a refractive index (n) and an extinction coefficient (k) ratio (n/k) of 0.3 to 1.2,
The low-reflective layer has a thickness of 10 to 200Å.
The organic electroluminescent device of claim 1, wherein the white (W) color filter is an organic layer disposed in the white (W) pixel area.
The organic light-emitting device of claim 2, wherein the low-reflective layer disposed in the white (W) pixel area is disposed between the organic layer and the substrate.
The method of claim 1, wherein the low-reflective layer is a first low-reflective layer and a second low-reflective layer formed on different layers in each of red (R), green (G), blue (B), and white (W) pixel areas. Organic electroluminescent device, characterized in that consisting of.
delete delete The organic electroluminescent device according to claim 1, wherein the low-reflective layer is made of chromium (Cr) or molybdenum (Mo).
The organic light emitting diode of claim 1, wherein the organic light emitting layer of the organic light emitting diode is a white organic light emitting layer.
A first substrate in which a plurality of red (R), green (G), blue (B), and white (W) pixel regions are partitioned;
A driving thin film transistor and an organic light emitting diode formed in pixel regions on the first substrate;
A capping layer formed on the driving thin film transistor and the organic light emitting diodes;
A second substrate facing the first substrate;
Red (R), green (G), blue (B) formed on the second substrate to correspond to the plurality of red (R), green (G), blue (B), and white (W) pixel regions White (W) color filters; And
In at least one of the red (R), green (G), blue (B) and white (W) pixel regions, a low-reflective layer disposed between the capping layer of the first substrate and the second substrate is formed. Including,
The low-reflective layer is a material having a refractive index (n) and an extinction coefficient (k) ratio (n/k) of 0.3 to 1.2,
The low-reflective layer has a thickness of 10 to 200Å.
A first substrate in which a plurality of red (R), green (G), blue (B), and white (W) pixel regions are partitioned;
A driving thin film transistor and an organic light emitting diode formed in pixel regions on the first substrate;
A capping layer formed on the driving thin film transistor and the organic light emitting diodes;
A second substrate facing the first substrate;
Red (R), green (G), blue (B) formed on the second substrate to correspond to the plurality of red (R), green (G), blue (B), and white (W) pixel regions White (W) color filters; And
In at least one of the red (R), green (G), blue (B) and white (W) pixel regions, a low-reflective layer disposed between the capping layer of the first substrate and the second substrate is formed. Including,
The white (W) color filter is a flat layer formed on the entire surface of the second substrate to cover the red (R), green (G), and blue (B) color filters.
The organic electroluminescent device of claim 10, wherein the low-reflective layer disposed in the white (W) pixel area is disposed between the flat layer and the second substrate.
The organic electroluminescent device according to claim 10, wherein the low-reflective layer is a material having a refractive index (n) and an extinction coefficient (k) ratio (n/k) of 0.3 to 1.2.
The organic electroluminescent device according to claim 10, wherein the low-reflective layer has a thickness of 10 to 200Å.
The organic electroluminescent device of claim 9, wherein the low-reflective layer is made of chromium (Cr) or molybdenum (Mo).
The organic light-emitting device of claim 9, wherein the organic light-emitting layer of the organic light-emitting diode is a white organic light-emitting layer.

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