KR20150065011A - Organic Light Emitting Display Device - Google Patents

Abstract

The present invention includes an organic light emitting display device which includes a display panel, and red, green, and blue sub pixels formed on the display panel. The red, green, and blue sub pixels are located between a bottom electrode and a light emitting layer and include mixing layers with a hole injection capacity and a hole transport capacity, respectively. The mixing layer is formed by mixing at least three heterogeneous materials.

Description

[0001] The present invention relates to an organic light emitting display device,

The present invention relates to an organic light emitting display.

An organic electroluminescent device used in an organic electroluminescent display device is a self-luminous device in which a light emitting layer is formed between two electrodes. An organic electroluminescent device is a device in which electrons and holes are injected into the light emitting layer from an electron injection cathode and an anode, respectively, and excitons, in which injected electrons and holes are combined, And emits light when it is dropped to the ground state.

The organic light emitting display device using the organic electroluminescent device has a top emission mode, a bottom emission mode and a dual emission mode depending on a direction in which light is emitted, Passive matrix type and active matrix type according to the type of the light source.

In the organic light emitting display, when a scan signal, a data signal, a power supply, and the like are supplied to a plurality of subpixels arranged in a matrix form, the selected subpixel emits light, thereby displaying an image.

A method of manufacturing a display panel of an organic light emitting display includes a deposition method, a solubilization method, and a hybrid method in which a deposition method and a solubilization method are combined. The hybrid scheme means that the organic light emitting diode included in the subpixel of the display panel is formed from a hole injecting layer to a light emitting layer using a solution or a solution method and using a deposition method from the light emitting layer to the electron injecting layer.

A buffer layer is present at the interface of the organic light emitting diode formed with the hybrid structure. The buffer layer transports electrons to the red and green light emitting layers, and has a high migration And should have a bipolar material capability with mobility.

In this case, the buffer layer should have good mobility for electrons and holes. However, if one of the mobility is insufficient, the charge balance is distorted and electrons or holes are formed in the buffer layer, not in the light emitting layer, . Therefore, the buffer layer existing at the interface of the organic light emitting diode formed with the hybrid structure causes a phenomenon of lowering the light efficiency when the injection of electrons or holes is not desired, and a method for improving the efficiency is required.

The present invention for solving the problems of the background art described above provides an organic electroluminescent display device which facilitates the solubilization process and can improve the light efficiency of the red, green and blue subpixels and simplify the process.

According to an aspect of the present invention, And a red, green, and blue subpixels formed on the display panel, wherein the red, green, and blue subpixels each include a mixed layer positioned between the lower electrode and the light emitting layer and having a hole injecting capability and a hole transporting capability, And the mixed layer is formed by mixing at least three heterogeneous materials.

The mixed layer may include a hole injection material, a hole transport material, and a transition metal compound material.

The mixing ratio of the hole injecting material, the hole transporting material, and the transition metal compound may have a relation of the hole injecting material, the hole transporting material, and the transition metal compound.

The hole injecting material may comprise 50 to 60 parts by weight, the hole transporting material may include 10 to 40 parts by weight, and the transition metal compound may be 0.1 to 5 parts by weight based on 100 parts by weight of the mixed layer.

The hole injecting material, the hole transporting material, and the transition metal compound material may be mixed in a ratio of 60: 35: 5.

The transition metal compound material may be an oxide.

The mixed layer and the light emitting layer may be formed by a solution process.

The blue light emitting layer is not formed in a BCL (Blue Common Layer) structure using a mixed layer formed by mixing a hole injecting material, a hole transporting material, and a transition metal compound material, but is positioned in the same layer as the red and green light emitting layers, There is an effect of providing an organic electroluminescent display device which can provide ease of use. Further, the present invention provides an organic electroluminescent display device which can simplify the process because the light efficiency of red, green and blue subpixels is improved by a single mixed layer through a solubilization process.

1 is a block diagram schematically showing an organic light emitting display device according to a first embodiment of the present invention.
Figure 2 is an illustration of the subpixel shown in Figure 1;
Fig. 3 schematically shows a cross section of the display panel shown in Fig. 1; Fig.
Fig. 4 is a first exemplary view showing a part of Fig. 3 in detail. Fig.
5 is a second exemplary view showing a part of FIG. 3 in detail;
6 is a cross-sectional structural view of a subpixel for explaining a hybrid method proposed in the related art.
FIG. 7 is a view showing a part of an organic light emitting layer included in a subpixel according to an embodiment of the present invention; FIG.
8 is a characteristic graph for an experimental example in which a hole injecting material and a hole transporting material are mixed.
9 is a characteristic graph of an embodiment of the present invention in which a hole injecting material, a hole transporting material, and a transition metal compounding material are mixed.
10 is a configuration diagram of a subpixel according to an embodiment of the present invention;
11 is a cross-sectional view of a subpixel according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram schematically showing an organic light emitting display according to an embodiment of the present invention. FIG. 2 is an exemplary view of the subpixel shown in FIG. 1, and FIG. 3 is a cross- 4 is a first exemplary view showing a part of FIG. 3 in detail, FIG. 5 is a second exemplary view showing a part of FIG. 3 in detail, and FIG. 6 is a cross- Sectional structure of a subpixel to be described.

1, an organic light emitting display according to an embodiment of the present invention includes a timing controller 120, a scan driver 130, a data driver 140, and a display panel 150. Referring to FIG.

The timing controller 120 collects device information (Extended Display Identification Data (EDID), compensation data, etc.) including the resolution, frequency, and timing information of the display panel 150 from an external memory unit through an I2C interface or the like. The timing controller 120 outputs a gate timing control signal GDC for controlling the operation timing of the scan driver 130 and a data timing control signal DDC for controlling the operation timing of the data driver 140. The timing controller 120 supplies the data driver 140 with the data signal DATA along with the data timing control signal DDC.

The data driver 140 samples and latches the data signal DATA in response to the data timing control signal DDC supplied from the timing controller 120, and converts the sampled data signal into a gamma reference voltage. The data driver 140 may be implemented as an integrated circuit (IC), mounted on the display panel 150, or mounted on an external substrate connected to the display panel 150. The data driver 140 supplies the data signal DATA to the sub-pixels SP included in the display panel 150 through the data lines DL.

The scan driver 130 outputs a scan signal while shifting the level of the gate voltage in response to the gate timing control signal GDC supplied from the timing controller 120. The scan driver 130 may be implemented as an integrated circuit and mounted on the display panel 150 or on an external substrate connected to the display panel 150. In addition, the scan driver 130 may be formed on the display panel 150 in the form of a gate-in-panel. The scan driver 130 supplies the scan signals to the sub-pixels SP included in the display panel 150 through the scan lines GL.

The display panel 150 displays an image corresponding to the scan signal supplied from the scan driver 130 and the data signal DATA supplied from the data driver 140. The display panel 150 includes sub-pixels SP for controlling light to display an image. The display panel 150 may be implemented by top emission, bottom emission, or dual emission depending on the structure of the subpixels SP.

As shown in FIG. 2, one subpixel SP is supplied with a scan signal supplied through a switching transistor SW and a switching transistor SW connected to a scan line GL1 and a data line DL1, And a pixel circuit PC that operates in response to the data signal DATA.

The pixel circuit PC includes a driving transistor, a capacitor, and an organic light emitting diode. When the pixel circuit PC includes a driving transistor, a capacitor, and an organic light emitting diode, the subpixel SP has a 2T (Transistor) 1C (Capacitor) structure. However, when a compensation circuit for compensating not only the driving transistor, the capacitor, and the organic light emitting diode but also the driving transistor is added to the pixel circuit PC, it is composed of 3T1C, 4T1C, 5T2C and the like.

The subpixels SP include red subpixels, green subpixels, and blue subpixels. However, it may be configured to include a white subpixel, a red subpixel, a green subpixel, and a blue subpixel in order to increase the light efficiency of the display panel 150 and to prevent the decline in luminance and color saturation of pure color. In this case, the white subpixel, the red subpixel, the green subpixel, and the blue subpixel may be implemented using a white organic light emitting diode and an RGB color filter, or may be implemented by a method in which a light emitting material included in an organic light emitting diode is formed in white, Or the like.

As shown in FIG. 3, the display panel 150 includes a lower substrate 151 and an upper substrate 152. The lower substrate 151 and the upper substrate 152 are bonded together by an adhesive such as a sealant. However, when the upper substrate 152 is made of a film, it is formed on the lower substrate 151 in the form of a deposition.

On one surface of the lower substrate 151, subpixels including an organic light emitting diode are formed. Subpixels including organic light emitting diodes and the like are vulnerable to outside air such as oxygen or moisture. Thus, an upper substrate 152 is formed on the lower substrate 151 to seal the sub-pixels.

On the upper substrate 152, a protective film 155 for protecting the upper surface of the display panel 150 is formed. The protective film 155 serves to prevent the display panel 150 from being damaged due to an external stimulus or impact that may be applied to the upper surface of the display panel 150, which may be omitted.

4 and 5, a switching transistor (not shown), a driving transistor DR, a capacitor (not shown) and an organic light emitting diode (OLED) are formed on one surface of the lower substrate 151. A switching transistor (not shown), a driving transistor DR, a capacitor (not shown) and an organic light emitting diode (OLED) are connected to various wirings formed on one surface of the lower substrate 151.

The driving transistor DR includes a gate electrode 161, a semiconductor layer 163, a source electrode 164a, and a drain electrode 164b. The gate electrode 161 is formed on one surface of the lower substrate 151. A first insulating layer 162 is formed on the gate electrode 161. The semiconductor layer 163 is formed on the first insulating film 162. The source electrode 164a and the drain electrode 164b are formed so as to be in contact with one side and the other side of the semiconductor layer 163, respectively. A second insulating film 165 is formed on the source electrode 164a and the drain electrode 164b.

The organic light emitting diode OLED includes a lower electrode 166, an organic light emitting layer 168, and an upper electrode 169. The lower electrode 166 is formed on the second insulating film 165. The lower electrode 166 is formed to be connected to the drain electrode 164b of the driving transistor DR exposed through the second insulating film 165. [ The lower electrode 166 is formed separately for each subpixel. The lower electrode 166 is selected as the anode electrode (or cathode electrode). On the lower electrode 166, a bank layer 167 is formed. The bank layer 167 is a layer that defines the opening region of the subpixel. An organic light emitting layer 168 is formed on the lower electrode 166.

The organic light emitting layer 168 includes a hole injection layer (HIL), a hole transport layer (HTL), a light emitting layer (EML), an electron transport layer (ETL) and an electron injection layer (EIL). However, at least one of the functional layers (HIL, HTL, ETL, EIL) other than the light emitting layer (EML) of the organic light emitting layer 168 may be omitted. The upper electrode 169 is formed on the organic light emitting layer 168. The upper electrode 169 is formed in the form of an opposing electrode commonly connected to all subpixels. The upper electrode 169 is selected as a cathode electrode (or an anode electrode).

As shown in FIG. 4, the upper substrate 152 may be formed in a multilayer film form or in a single film form, though it is not shown. When the upper substrate 152 is formed in the form of a multilayer film, it may be formed of an organic film and an inorganic film, and when the upper substrate 152 is formed in the form of a single layer film, it may be formed of an organic film or an inorganic film.

As shown in FIG. 5, the upper substrate 152 may be formed in the form of N (N is an integer of 3 or more) layer film. In this case, the upper substrate 152 may be formed of an organic-inorganic hybrid layer composed of the organic layer 152a, the inorganic layer 152b, the organic layer 152c, and the inorganic layer 152d. Although not shown, the interior of the organic / inorganic composite layer may further include a moisture absorption layer or the like for absorbing moisture or oxygen.

Meanwhile, the organic light emitting diodes included in the sub-pixels of the display panel are formed in a hybrid manner. Hereinafter, problems of the conventional hybrid method will be described.

As shown in FIG. 6, in the conventional hybrid method, a solution process is used from the hole injection layer 168_HIL to the red and green light emitting layers 168R and 168G, and the buffer layer 168 BUF) The evaporation process is used from the light emitting layer 168B to the upper electrode 169. [

A buffer layer 168_BUF exists at the interface of the organic light emitting diode formed with the conventional hybrid structure. The buffer layer 168_BUF transfers electrons to the red and green light emitting layers 168R and 168G and emits electrons to the blue light emitting layer 168B It must have a bipolar material capability with high mobility so that holes can be injected smoothly.

The buffer layer 168_BUF should have good mobility with respect to electrons and holes. However, if either one of the mobility is insufficient, the charge balance is distorted and electrons or holes are injected into the light emitting layers 168R, 168G, and 168B The buffer layer 168_BUF is formed in the buffer layer 168_BUF to reduce color purity and light efficiency.

As a result of an experiment using the conventional hybrid structure shown in FIG. 6, a color interference phenomenon in which a blue peak occurs in the spectrum for red and green was observed. The color interference phenomenon in which a blue peak occurs in red and green is due to the fact that the buffer layer 168_BUF can not smoothly transport electrons to the red and green light emitting layers 168R and 168G.

On the other hand, when the buffer layer 168_BUF interposed in the conventional hybrid structure is not used, it is possible to reduce the problem that blue color interferes with red and green. However, if the buffer layer 168_BUF is not used for the blue light emitting layer 168B, the recombination region of electrons and holes is formed at the interface between the solubilized layer and the deposited layer, thereby reducing the efficiency and lifetime of the device.

FIG. 7 is a graph showing a partial layer of the organic light emitting layer included in a subpixel according to an embodiment of the present invention, FIG. 8 is a characteristic graph of an experimental example in which a hole injecting material and a hole transporting material are mixed, A hole injecting material, a hole transporting material, and a transition metal compounding material according to an embodiment of the present invention.

7, an embodiment of the present invention includes a method of mixing at least three different materials between the lower electrode 166 and the red, green, and blue light emitting layers 168RGB to overcome and overcome the problems described above Thereby forming a mixed layer 168_MIX.

The mixed layer 168_MIX is made of a hole injecting material, a hole transporting material, and a transition metal compounding material. The mixed layer 168_MIX in which the hole injecting material, the hole transporting material and the transition metal compounding material are mixed can serve as the hole injecting layer and the hole transporting layer, so that the process can be simplified while improving the characteristics of the device. That is, the mixed layer 168_MIX has a hole injecting ability and a hole transporting ability.

In addition, it has been shown that the conventional buffer layer can be eliminated (or omitted) by forming the mixed layer 168_MIX in which the hole injecting material, the hole transporting material and the transition metal compound material are mixed to have the above characteristics. It is explained by the experimental results.

As shown in FIG. 8, the voltage VJ plot, the luminance and the brightness (Lum. Cd (cd) for the HIL + HTL) obtained by mixing the comparative example (Ref.) With the hole injecting material and the hole transporting material / A) and a spectrum graph are shown.

The comparative example (Ref.) Corresponds to the subpixel described with reference to FIG. Experimental examples (HIL + HTL) were a first experiment (HIL + HTL (10%) in which a hole transport material was mixed with 10% of a hole injecting material, a second experiment Experimental Example 3 (HIL + HTL (20%), HIL + HTL (30%) in which 30% of the hole transport material was mixed with the hole transport material, 40% Example 4 (HIL + HTL (40%)).

As can be seen from the experimental examples (HIL + HTL), the mixing ratio of the hole transporting material to the hole injecting material was increased to 10 to 40%, and their characteristics were observed in comparison with the comparative example (Ref.).

As can be seen from the experimental examples (HIL + HTL), when the hole injecting material and the hole transporting material are mixed, the driving voltage is increased and the light efficiency is lowered compared with the comparative example (Ref.). In addition, even if the ratio of the hole injecting material is increased, the injection rate of holes is not increased much. As a result, it has been found that it is difficult to greatly improve the performance of the device merely by mixing the hole injecting material and the hole transporting material.

However, it has been confirmed that a single mixed layer of a hole injecting material and a hole transporting material can serve as a hole injecting layer and a hole transporting layer, and if the hole injecting ability can be improved, I can deduce that I can satisfy it.

As shown in FIG. 9, an embodiment of the present invention is a method of mixing a hole injecting material, a hole transporting material, and a transition metal compound material to form a single mixed layer, (HIL + HTL) mixed layer.

As can be seen from the graph of the VJ plot in FIG. 9, the application of the mixed layer (HIL + HTL + α) according to an embodiment of the present invention increases the driving voltage of the comparative example (Ref. (HIL + HTL).

As can be seen from the graph of brightness and brightness (Lum. Vs cd / A) in FIG. 9, the mixed layer (HIL + HTL + The brightness and brightness were improved to a substantially high level, which was almost similar to the brightness and brightness of the comparative example (Ref.).

(HIL + HTL + alpha) according to an embodiment of the present invention, as shown in the spectrum graph of FIG. 9, And showed almost the same level without any problems in the spectrum.

In one embodiment of the present invention, a transition metal compound material corresponding to an oxide in the form of powder is added based on the above experimental examples. As a result, as shown in the graph of FIG. 9, the mixed layer (HIL + HTL +?) Constructed according to one embodiment of the present invention showed superior performance compared to the experimental examples (HIL + HTL).

The mixing ratio between the hole injecting material, the hole transporting material and the transition metal compound used in the embodiment will be described as follows.

8 and 9, the base material of the mixed layer (HIL + HTL + alpha) corresponds to the hole injecting material, and the hole transporting material and the transition metal compound material correspond to the additive material. Therefore, when the mixing ratio between the hole injecting material, the hole transporting material and the transition metal compounding material is expressed as a relational expression, it is expressed as a hole injecting material> a hole transporting material> a transition metal compounding material.

Since the hole injecting material corresponds to the base material of the mixed layer (HIL + HTL + alpha), the hole injecting material can be injected only when the hole transporting material and the transition metal compounding material take more weight than the sum of the hole transporting material and the transition metal compounding material. If the ratio of the hole injecting material is too small or too large, the hole injecting ability may be deteriorated and the ratio of other additive materials may be lowered, which may deteriorate the hole transporting ability. Therefore, the hole injecting material preferably accounts for 50 to 60 parts by weight based on 100 parts by weight of the total amount of the mixed layer.

As can be seen from FIGS. 8 and 9, when the ratio of the hole transporting material is increased relative to the hole injecting material, the hole injection is not performed well, and the voltage increases. However, as the transition metal compound material is added, such a tendency is not seen, and the tendency is gradually decreased in the driving voltage direction similar to that of the comparative example. However, as the proportion of the hole transport material increases, the light efficiency is greatly reduced, so the mixing ratio of the transition metal compound should be considered. Therefore, the hole transporting material preferably accounts for 10 to 40 parts by weight based on 100 parts by weight of the total amount of the mixed layer.

As can be seen from FIGS. 8 and 9, the transition metal compound material improves the hole injecting ability to lower the driving voltage in order to compensate for and improve defects due to the mixture of the hole injecting material and the hole transporting material. The transition metal compound material may be modified to improve the injection ability of holes, and thus only a small amount of the transition metal compound material is included. When the transition metal compound material is mixed at a high ratio, the mixed layer can be modified only by one of the functions without simultaneously performing the role of the hole injection and the hole transport layer. Therefore, the transition metal compound material preferably accounts for 0.1 to 5 parts by weight based on 100 parts by weight of the total amount of the mixed layer.

Meanwhile, the mixed layer (HIL + HTL + alpha) according to the embodiment of FIG. 9 is an experimental result when a hole injecting material, a hole transporting material, and a transition metal compound material are formed at a ratio of 60: 35: 5. Therefore, it is apparent that the characteristics of the mixed layer (HIL + HTL + alpha) are not limited to these, and the characteristics of the mixed layer (HIL + HTL + alpha) Therefore, the characteristics of the subpixel to which the mixed layer (HIL + HTL + alpha) according to the embodiment of the present invention is applied are not limited thereto.

Meanwhile, the hole transporting materials used in the examples and examples of FIGS. 8 and 9 are the hole transporting material (HTL A), the hole transporting material (HTL B) and the hole transporting material Substance (HTL C).

In Table 1, "HOMO / LUMO" means homo and ramo levels, "T1" means triplet level, "Tg" means glass transition temperature, "μ _h " means hole mobility and "Morphology" means morphology.

Hereinafter, a subpixel including a mixed layer (HIL + HTL +?) According to an embodiment of the present invention will be described.

FIG. 10 is a configuration diagram of a subpixel according to an embodiment of the present invention, and FIG. 11 is a sectional view of a subpixel according to an embodiment of the present invention.

As shown in FIG. 10, a subpixel according to an exemplary embodiment of the present invention includes a lower electrode 166, an organic emission layer 168, and an upper electrode 169. The lower electrode 166 is selected as the anode electrode and the upper electrode 169 is selected as the cathode electrode.

The organic luminescent layer 168 includes a mixed layer 168_MIX, red, green and blue luminescent layers 168RGB and an electron transport layer 168_ETL. The mixed layer 168_MIX is a layer in which a hole injecting material, a hole transporting material, and a transition metal compounding material are mixed as revealed in the experiment described above.

11, a mixed layer 168_MIX is formed on the lower electrode 166, and red, green and blue light emitting layers 168RGB are formed on the mixed layer 168_MIX. The electron transporting layer 168_ETL is formed on the red, green and blue light emitting layers 168RGB. The electron injection layer and the upper electrode 169 are formed on the electron transport layer 168_ETL.

The mixed layer 168_MIX and the red, green and blue light emitting layers 168RGB are formed by a solution process or a solution process. The electron transport layer 168_ETL, the electron injection layer and the upper electrode 169 are formed by an evaporation process, . Soluble or Solution Processes include solution processes such as inkjet printing, nozzle printing, transferring, slit coating, gravure printing and thermal jet printing.

As described above, the blue light emitting layer is not formed in a BCL (Blue Common Layer) structure using a mixed layer formed by mixing a hole injecting material, a hole transporting material, and a transition metal compound material and is positioned in the same layer as the red and green light emitting layers. The present invention provides an organic electroluminescent display device capable of improving the ease of operation of the organic electroluminescent display device. Further, the present invention provides an organic electroluminescent display device which can simplify the process because the light efficiency of red, green and blue subpixels is improved by a single mixed layer through a solubilization process.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

120: a timing controller 130: a scan driver
140: Data driver 150: Display panel
166: lower electrode 168: organic light emitting layer
168_MIX: mixed layer 168R, 168G, 168B: light emitting layer
168_ETL: electron transport layer 169: upper electrode

Claims (7)

Display panel; And
And red, green, and blue subpixels formed on the display panel,
The red, green and blue sub-
And a mixed layer positioned between the lower electrode and the light emitting layer and having a hole injecting capability and a hole transporting capability,
Wherein the mixed layer is formed by mixing at least three different materials. The method according to claim 1,
The mixed layer
A hole injecting material, a hole transporting material, and a transition metal compound material. 3. The method of claim 2,
The mixing ratio of the hole injecting material, the hole transporting material, and the transition metal compound is
Wherein the hole injecting material, the hole transporting material, and the transition metal compound are in the relationship of the hole injecting material, the hole transporting material, and the transition metal compound. 3. The method of claim 2,
With respect to a total of 100 parts by weight of the mixed layer
The hole injecting material accounts for 50 to 60 parts by weight,
The hole transport material may be 10 to 40 parts by weight,
Wherein the transition metal compound material comprises 0.1 to 5 parts by weight of the transition metal compound material. The method according to claim 1,
Wherein the hole injecting material, the hole transporting material, and the transition metal compound material are
60: 35: 5. ≪ RTI ID = 0.0 > 5. 3. The method of claim 2,
Wherein the transition metal compound material is an oxide. The method according to claim 1,
The mixed layer and the light emitting layer
Wherein the organic electroluminescent display device is formed by a solution process.

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