KR102486234B1 - Organic light emitting display panel - Google Patents

Abstract

An organic light emitting display panel according to an embodiment of the present specification includes a transistor including an active layer on a substrate, an organic light emitting element including an anode, an organic light emitting layer, and a cathode on the transistor, and a planarization layer between the transistor and the organic light emitting element. , A bank layer on the planarization layer and partially covering the anode, and a hydrogen blocking film for blocking hydrogen generated from any one of the organic light emitting layer, the planarization layer, and the bank layer from flowing into the active layer, wherein the hydrogen blocking film is planarized By forming it under the layer, hydrogen is blocked from entering the active layer, and thus the performance of the transistor can be prevented from being reduced.

Description

Organic light emitting display panel {ORGANIC LIGHT EMITTING DISPLAY PANEL}

The present specification relates to an organic light emitting display panel, and more particularly, to an organic light emitting display panel for preventing performance deterioration of a transistor.

An organic light emitting display panel includes an organic light emitting device having an organic light emitting layer, an anode, and a cathode, and a pixel driving circuit (eg, an organic light emitting device) for driving the organic light emitting device. For example, transistors, capacitors, etc.) are provided. Specifically, in the organic light emitting display panel, holes and electrons respectively injected from an anode and a cathode recombine in the light emitting layer to form excitons, and light of a specific wavelength is generated by emitting energy from the formed excitons. It is a display panel using the phenomenon of Therefore, the organic light emitting display panel has advantages such as fast response speed, high contrast ratio, luminous efficiency, luminance and viewing angle by using organic light emitting elements that emit light themselves.

In the organic light emitting display panel, pixels including an organic light emitting element and a pixel driving circuit are arranged, and luminance of an image implemented in the pixels is adjusted according to a gray level of image data. The pixel driving circuit includes transistors and capacitors, and the transistors include a gate electrode, a source electrode, and a drain electrode. Among the transistors, the driving transistor controls the driving current flowing through the organic light emitting diode according to the voltage applied between the gate electrode and the source electrode. Therefore, the light emission amount and luminance of the organic light emitting diode are determined according to the driving current.

In general, when the driving transistor operates in a saturation region, the driving current Ids flowing between the drain electrode and the source electrode of the driving transistor is expressed as follows.

Here, μ represents the electron mobility, C represents the capacitance of the gate insulating film, W represents the channel width of the driving transistor, and L represents the channel length of the driving transistor. Vgs represents the voltage between the gate electrode and the source electrode of the driving transistor, and Vth represents the threshold voltage (or threshold voltage) of the driving transistor. Depending on the pixel structure, the voltage Vgs between the gate electrode and the source electrode of the driving transistor may be a difference voltage between the data voltage and the reference voltage. Since the data voltage is an analog voltage corresponding to the gray level of the image data and the reference voltage is a fixed voltage, the voltage Vgs between the gate electrode and the source electrode of the driving transistor is programmed according to the data voltage. The driving current Ids is determined according to the programmed voltage Vgs between the gate electrode and the source electrode.

Since the electrical characteristics of the pixel, such as the threshold voltage (Vth) of the driving transistor, the electron mobility (μ) of the driving transistor, and the threshold voltage of the organic light emitting device, are factors that determine the driving current (Ids), all pixels must be the same in , to implement a uniform picture quality. However, electrical characteristics may vary between pixels due to various causes such as process deviation and change over time.

A switching transistor constituting the pixel driving circuit serves as a switching element that applies data through turn-on and turn-off operations.

Since the driving transistor or the switching transistor is degraded when stressed by heat or pressure or subjected to an external stimulus, deviations may occur between pixels. Therefore, a method for protecting the transistor from external stimuli is needed.

Organic light emitting display panels can be classified into bottom emission types and top emission types. In the case of the bottom emission type organic light emitting display panel, the light generated from the light emitting layer is reflected by the cathode and emitted to the lower part of the organic light emitting display panel. In the case of the top emission type organic light emitting display panel, the light must be emitted through the cathode. Form translucent or transparent. A metal film such as aluminum (Al) may be used as the cathode, and the thickness of the cathode may be adjusted according to the emission method of the organic light emitting display panel.

An organic light emitting display panel is formed of various organic or inorganic material layers, and the organic or inorganic material layers generate hydrogen during deposition. During the manufacturing process of the organic light emitting display panel, hydrogen diffused from the organic material layer or the inorganic material layer is blocked by the cathode, so hydrogen cannot escape to the outside and is trapped inside the organic light emitting display panel. Hydrogen trapped inside the organic light emitting display panel affects the transistor, causing pixel defects such as bright spots and dark spots.

Accordingly, the inventors of the present specification have recognized the above-mentioned problems and have developed a technique for preventing defects of organic light emitting display panels caused by hydrogen.

An object to be solved according to an embodiment of the present specification is to provide an organic light emitting display panel capable of preventing diffusion of hydrogen that may affect a transistor into the transistor.

The tasks of the present specification are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the description below.

In the organic light emitting display panel according to one embodiment of the present specification, the organic light emitting display panel includes a transistor including an active layer on a substrate, an organic light emitting element including an anode, an organic light emitting layer, and a cathode on the transistor, and a transistor A planarization layer between the organic light emitting elements, a bank layer on the planarization layer and covering a part of the anode, and blocking hydrogen generated from at least one of the organic light emitting layer, the planarization layer, and the bank layer from flowing into the active layer. A hydrogen barrier layer is included, and the hydrogen barrier layer is below the planarization layer. Therefore, by blocking the inflow of hydrogen into the active layer, the performance of the transistor may be prevented from deteriorating.

In the organic light emitting display panel according to an exemplary embodiment of the present specification, the organic light emitting display panel includes a transistor on a substrate, an organic light emitting element including an anode, an organic light emitting layer, and a cathode on the transistor, and a gap between the transistor and the organic light emitting element. Contains hydrogen blocking material. Therefore, by blocking the inflow of hydrogen into the active layer, the performance of the transistor may be prevented from deteriorating.

In the method for manufacturing an organic light emitting display panel according to an embodiment of the present specification, the method includes forming a transistor on a substrate, forming a passivation layer on the transistor, and planarizing the passivation layer. A step of forming a layer, and a step of forming an organic light emitting device on the planarization layer, and the passivation layer is formed of aluminum oxide (Al ₂ O ₃ ). Therefore, by blocking the inflow of hydrogen into the active layer, the performance of the transistor may be prevented from deteriorating.

Other embodiment specifics are included in the detailed description and drawings.

According to the embodiments of the present specification, by disposing a hydrogen blocking film between the transistor and the organic light emitting diode, it is possible to prevent the performance of the transistor from being reduced by blocking hydrogen from flowing into the active layer.

In addition, according to embodiments of the present specification, by disposing a hydrogen blocking film on the oxide transistor, it is possible to prevent the performance of the oxide transistor from being reduced by preventing the active layer of the oxide transistor from conducting.

In addition, according to the embodiments of the present specification, by forming the hydrogen blocking film to a thickness of 100 Å to 200 Å, it is possible to block hydrogen from flowing into the active layer of the transistor and to facilitate the manufacture of the hydrogen blocking film.

Also, according to the embodiments of the present specification, in a display panel including transistors using two or more types of active layers, a hydrogen blocking layer may be formed on the transistors, thereby reducing variations in performance of the transistors.

Since the content of the specification described in the problem to be solved, the problem solution, and the effect above does not specify the essential features of the claim, the scope of the claim is not limited by the matters described in the content of the specification.

1 is a diagram illustrating a display device according to an exemplary embodiment of the present specification.
2 is a circuit diagram illustrating a pixel driving circuit according to an exemplary embodiment of the present specification.
3 is a cross-sectional view illustrating a display panel according to an exemplary embodiment of the present specification.
FIG. 4 is a view showing a part of FIG. 1 .
5 is a view showing a display panel according to another exemplary embodiment of the present specification.
6A to 6D are cross-sectional views illustrating a method of manufacturing a passivation layer according to an embodiment of the present specification.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention belongs. It is provided to fully inform the holder of the scope of the invention, and the present 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 illustrative, so the present invention is not limited to the details shown. Like reference numbers designate like elements throughout the specification. In addition, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists of', etc. mentioned in this specification is used, other parts may be added unless 'only' is used. In the case where a component is expressed in the singular, the case including the plural is included unless otherwise explicitly stated.

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

In the case of a description of a positional relationship, for example, 'on top of', 'on top of', 'at the bottom of', 'next to', etc. Or, unless 'directly' 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, when a temporal precedence relationship is described as 'after', 'continue to', 'after ~', 'before', etc., 'immediately' or 'directly' As long as ' is not used, non-continuous cases may also be included.

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

Each feature of the various embodiments of the present specification can be partially or entirely combined or combined with each other, technically various interlocking and driving are possible, and each embodiment can be implemented independently of each other or can be implemented together in an association relationship. may be

Hereinafter, a transistor substrate according to an embodiment of the present specification and a display panel using the same will be described with reference to the accompanying drawings.

1 is a diagram illustrating a display device according to an exemplary embodiment of the present specification.

Referring to FIG. 1 , a display device 1000 includes a display panel 500 , a timing controller 800 , a data driver 700 , and a gate driver 600 .

The display panel 500 includes subpixels P to which data lines 10 and gate lines 20 are connected. The display panel 500 is sealed to protect at least one film or substrate and sub-pixels formed on the film or substrate from external air such as moisture or oxygen.

The display panel 500 includes a display area DA where subpixels are formed and a non-display area NDA where various signal lines or pads are formed outside the display area DA. The display area DA is an area where subpixels are located because it is an area that displays an image, and the non-display area NDA is an area where dummy subpixels are located or no subpixels are located because it is an area that does not display an image. The display panel 500 may be implemented as a top-emission method, a bottom-emission method, or a dual-emission method according to a configuration method of the sub-pixel P.

The gate driving circuit 600 is connected to the gate lines 20 to supply gate signals. Specifically, the gate driving circuit 600 receives a gate control signal including clock signals and a start voltage from the level shifter. The gate driving circuit 600 generates gate signals according to the clock signals and the start voltage and provides them to the gate lines 20 .

The level shifter shifts the voltage levels of the clock signals and the start voltage input from the timing controller 800 to gate-on voltages and gate-off voltages capable of switching transistors formed on the display panel. The level shifter supplies level-shifted clock signals to the gate driving circuit 600 through clock lines and supplies the level-shifted start voltage to the gate driving circuit 600 through a start voltage line. Since the clock lines and the start voltage line are lines for transmitting clock signals corresponding to gate control signals and a start voltage, the clock lines and the start voltage line may be collectively referred to as a gate control line.

The data driving circuit 700 is connected to the data lines 10 . The data driving circuit 700 receives digital image data and a data control signal from the timing controller 800 . The data driving circuit 700 converts digital image data into analog data voltages according to a data control signal. The data driving circuit 700 supplies analog data voltages to the data lines 10 .

The timing controller 800 receives digital image data and timing signals from an external system board. The timing signals may include a vertical sync signal, a horizontal sync signal, and a data enable signal.

The timing controller 800 generates a gate control signal for controlling the operation timing of the gate driving circuit 600 and a data control signal for controlling the operation timing of the data driving circuit 700 based on the timing signals.

The data driving circuit 700, the level shifter, and the timing controller 800 may be formed as a single driving IC. In addition, the driving IC integrated into one may be disposed on the display panel 500 . The embodiment of the present specification is not limited thereto, and each of the data driving circuit 700, the level shifter, and the timing controller 800 may be formed as a separate driving IC.

2 is a circuit diagram illustrating a pixel driving circuit according to an exemplary embodiment of the present specification.

Transistors constituting the pixel driving circuit may be implemented as N-type or P-type MOSFET (Metal Oxide Semiconductor Field Effect Transistor) transistors. A transistor is a three-terminal device including a gate electrode, a source electrode, and a drain electrode. The source electrode is an electrode that supplies carriers to the transistor. In a transistor, carriers start flowing from the source electrode. And, the drain electrode is an electrode through which carriers exit the transistor. That is, the flow of carriers in the MOSFET flows from the source electrode to the drain electrode. In the case of an N-type transistor, since electrons are carriers, the voltage of the source electrode is lower than the voltage of the drain electrode so that electrons can flow from the source electrode to the drain electrode. Since electrons flow from the source electrode to the drain electrode in the N-type transistor, the direction of current flows from the drain electrode to the source electrode. In the case of a P-type transistor, since a carrier is a hole, the voltage of the source electrode is higher than the voltage of the drain electrode so that holes can flow from the source electrode to the drain electrode. In a P-type transistor, since holes flow from the source electrode to the drain electrode, current flows from the source electrode to the drain electrode. The source and drain electrodes of the MOSFET are not fixed and can be changed according to the applied voltage.

2 illustrates a P-type transistor as an example. The circuit diagram shown in FIG. 2 is a circuit diagram of 2T1C (two transistors and one capacitor) for supplying current to an organic light emitting device, but is not limited thereto, and various circuit diagrams such as 3T1C, 4T2C, 5T1C, 6T1C, and 7T1C are displayed. Applicable to panels. In addition, it may be a circuit that drives not only an organic light emitting device but also a liquid crystal device or a quantum dot device.

The pixel driving circuit shown in FIG. 2 includes a switching transistor ST, a driving transistor DT, and a capacitor C.

The gate electrode of the switching transistor ST is connected to the scan line, the source electrode of the switching transistor ST is connected to the data line, and the drain electrode of the switching transistor ST is connected to the gate electrode of the driving transistor DT. . When the switching transistor ST is turned on by the scan signal Scan applied through the scan line, the data voltage Vdata provided through the data line is applied to the gate electrode of the driving transistor DT.

The gate electrode of the driving transistor DT is connected to the drain electrode of the switching transistor ST, the source electrode of the driving transistor DT is connected to a high potential voltage line, and the drain electrode of the driving transistor DT is an organic light emitting device. It is connected to the anode of (OLED). When the switching transistor ST is turned on and the data voltage Vdata is applied to the gate electrode of the driving transistor DT, the driving transistor DT is turned on and the organic light emitting diode OLED is provide current. The capacitor C is connected between the source electrode of the driving transistor DT and the gate electrode of the driving transistor DT, and the high potential voltage VDD applied to the source electrode of the driving transistor DT and the driving transistor DT A voltage difference between data voltages (Vdata) applied to the gate electrode of V is stored so that a constant current can be provided to the organic light emitting device. A cathode of the organic light emitting device is connected to a low potential voltage line to receive a low potential voltage (VSS).

Transistors can be classified into amorphous silicon transistors (a-Si transistors), polycrystalline silicon transistors (p-Si transistors), single-crystal silicon transistors (c-Si transistors), and oxide transistors according to the type of active layer. . Performance of the transistor may vary depending on the type of the active layer, and as mentioned above, performance may deteriorate when exposed to external stimuli. In order to improve the performance of the organic light emitting display panel, transistors using two or more types of active layers may be formed according to the type of transistor and the role of the transistor. For example, polycrystalline semiconductor materials have high mobility (more than 100 cm 2 /Vs), low energy consumption and excellent reliability. And, the oxide semiconductor material has a low off-state current. The off-state current is the leakage current between the source and drain of the transistor in the off-state. Since the transistor element having a low off-state does not have leakage current even when the off-state is long, a change in luminance of the pixels can be minimized when the pixels are driven at a low speed.

In the case of a display panel including transistors using two or more types of active layers, a technique for reducing variations in performance of the transistors is required. Hereinafter, a driving transistor DT formed of an oxide transistor among organic light emitting display panels including a polycrystalline silicon transistor and an oxide transistor will be described as an example.

FIG. 3 is a cross-sectional view of a display panel 500 according to an exemplary embodiment of the present specification, and illustrates the driving transistor DT and the organic light emitting device OLED of FIG. 2 .

Referring to FIG. 3 , the display panel 500 is an organic light emitting display panel, and the pixel driving circuit, the organic light emitting diode (OLED), and the pixel driving circuit and the organic light emitting diode (OLED) are protected from oxygen and moisture that may be introduced from the outside. It includes an encapsulation layer 400 to protect.

The driving transistor DT providing driving current to the organic light emitting diode OLED will be described as an example. In addition, the driving transistor DT is shown as a bottom-gate staggered structure, but is not limited thereto, and a bottom-gate coplanar structure, a top-gate staggered structure ( It may also be a top-gate staggered structure, and a top-gate coplanar structure.

Briefly about the structure of the transistor, the transistor has a top-gate structure in which the gate electrode is located on top of the active layer according to the method of arranging the gate electrode, source electrode, drain electrode, and active layer, the gate It can be classified as a bottom-gate or inverted structure in which the electrode is located below the active layer, and the gate electrode, source electrode, and drain electrode are separated up and down based on the active layer. It can be divided into a staggered structure having a structure and a coplanar structure in which a source electrode and a drain electrode are formed in parallel with an active layer. That is, the structure of the transistor may be a staggered structure (or top-gate staggered structure), an inverted staggered structure (or bottom-gate staggered structure), and a coplana structure (or top-gate coplana structure). , and an inverted coplana structure (or bottom-gate coplana structure).

Referring to FIG. 3 , a gate electrode 202 is disposed on a substrate 100 and a gate insulating layer 102 is formed on the gate electrode 202 . The gate insulating film 102 covers the gate electrode 202 to insulate the gate electrode 202 from the active layer 204 on the gate insulating film 102 . A source electrode 206 and a drain electrode 207 are disposed on the active layer 204 to contact the active layer 204 . A first passivation layer 104 covering the driving transistor DT is formed on the driving transistor DT composed of the gate electrode 202 , the source electrode 206 , and the drain electrode 207 . A second passivation layer 105 may be disposed on the first passivation layer 104 . By forming the first passivation layer 104 and the second passivation layer 105 with different materials, moisture permeation may be prevented and the driving transistor DT may be protected from contamination or damage. The first passivation layer 104 and the second passivation layer 105 are inorganic layers and are formed along curves of the driving transistor DT formed on the substrate 100 . A planarization layer 106 is formed on the second passivation layer 105 to flatten the curves of the substrate 100 .

The gate electrode 202, the source electrode 206, and the drain electrode 207 may be a semiconductor such as silicon (Si) or a conductive metal such as molybdenum (Mo), aluminum (Al), chromium (Cr), or gold. It may be any one of (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu), an alloy of two or more, or a multilayer thereof.

In addition, the gate insulating film 102, the first passivation layer 104, and the second passivation layer 105 may be silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiONx) or a multilayer thereof, , The planarization layer 106 is an acrylic resin, an epoxy resin, a phenol resin, a polyamide resin, a polyimide resin, an unsaturated polyester resin, a polyphenylene resin, a polyphenylene sulfide resin, a benzocyclobutene, and a photoresist. It may be formed as one of, but is not limited thereto.

An organic light emitting diode (OLED) is disposed on the planarization layer 106 , and the organic light emitting diode (OLED) includes an anode 302 , an organic light emitting layer 304 , and a cathode 306 . A hole injection layer and a hole transport layer may be included between the organic light emitting layer 304 and the anode 302, and an electron transport layer and an electron injection layer may be included between the organic light emitting layer 304 and the cathode 306, It is not limited to this. In addition, the organic light emitting layer 304 may be a single layer as a light emitting layer that emits red, blue, green, or similar colors, and has a tandem structure including two or more light emitting layers and a charge generation layer between the light emitting layer and the light emitting layer. structure) may be

The anode 302 may be disposed separately for each sub-pixel, is an electrode supplying or transferring holes to the organic light emitting layer 304, and is a source of the driving transistor DT disposed on the substrate 100. It is connected to the electrode 206 or the drain electrode 207. 3, the anode 302 contacts the drain electrode 207 of the driving transistor DT through contact holes formed in the first passivation layer 104, the second passivation layer 105, and the planarization layer 106. The structure is explained with an example. In the case of the bottom emission method, the anode 302 may be made of a transparent conductive oxide material such as indium tin oxide (ITO) or indium zinc oxide (IZO), which is a transparent layer, and in the case of the top emission method. , It may be a two-layer structure in which a reflective layer is laminated on a transparent layer, or a three-layer structure in which a transparent layer, a reflective layer, and a transparent layer are laminated, and the reflective layer includes copper (Cu), silver (Ag), palladium (Pd), aluminum (Al), It may be made of a metal material such as platinum (Pt), gold (Au), chromium (Cr), tungsten (W), molybdenum (Mo), titanium (Ti), or iridium (Ir). Also, the anode 302 may be a single layer made of a material having characteristics of a transparent layer and a reflective layer.

A bank layer 108 covering an edge of the anode 302 is formed on the anode 302 except for the light emitting region of the sub-pixel. The bank layer 108 may serve to divide regions between sub-pixels. A spacer 109 is disposed in a partial region on the bank layer 108 . The spacer 109 may prevent damage to the bank layer 108 due to contact between the bank layer 108 and the fine metal mask when the fine metal mask is disposed on the bank layer 108 to form the organic light emitting layer 304 . can

The bank layer 108 and the spacer 109 may be formed of any one of polyimide, photo acryl, and benzocyclobutene (BCB), which are transparent organic insulating materials, but are not limited thereto.

The cathode 306 is commonly disposed in a plurality of subpixels and is an electrode supplying or transferring electrons to the organic light emitting layer 304 . The cathode 306 may be formed of silver (Ag), magnesium (Mg), or an alloy thereof, or an alloy of these and other metals in the case of a bottom emission method, and in the case of an upper emission method, such a metal material is very It may have a transparent characteristic by forming it with a thin thickness. Alternatively, like the transparent layer of the anode 302, it may be made of a transparent conductive oxide material such as indium tin oxide or indium zinc oxide.

The encapsulation layer 400 is disposed on the organic light emitting diode (OLED) to protect the organic light emitting diode (OLED) from moisture or oxygen. The encapsulation layer 400 includes a first encapsulation layer 402 , a second encapsulation layer 404 , and a third encapsulation layer 406 . The first encapsulation layer 402 and the third encapsulation layer 406 are inorganic insulating layers and may be made of any one or more of silicon nitride (SiNx), silicon oxide (SiOx), or silicon oxynitride (SiON), Not limited to this. Also, the second encapsulation layer 402 is an organic insulating layer and may be formed of a polymer. The second encapsulation layer 402 is also called a particle covering layer (PCL) and serves to cover foreign matter. For example, a third encapsulation layer 406 made of an inorganic insulating material is disposed on the first encapsulation layer 402 without the second encapsulation layer 402 in a state in which foreign substances are attached to the surface of the first encapsulation layer 402 . In this case, since the third encapsulation layer 406 does not have high adhesion to the foreign material attached to the surface of the first encapsulation layer 402, a gap may occur around the foreign material, and the third encapsulation layer 406 may be formed due to the formation of the gap. may be peeled off. Therefore, by disposing the second encapsulation layer 404 formed of an organic material between the first encapsulation layer 402 and the third encapsulation layer 406, the third encapsulation layer 406 is peeled off by covering the foreign matter and the surroundings of the foreign matter. can prevent it from happening.

In addition, a capping layer may be disposed between the encapsulation layer 400 and the cathode 306 . The capping layer covers the organic light emitting device 304 to prevent inflow of oxygen and moisture from the outside, and can serve to improve the efficiency of light passing through the cathode 306, and the encapsulation layer 400 and the cathode The adhesion of (306) can be improved.

FIG. 4 is a view showing a part of FIG. 3 . Specifically, it is a cross-sectional view schematically showing a stacked structure from the active layer 204 to the first encapsulation layer 402 . In addition, in FIG. 4, a case in which the cathode 306 is formed of aluminum (Al) will be described as an example. In FIG. 4 , overlapping descriptions with those of FIG. 3 may be omitted or briefly described.

When the cathode 306 is formed of aluminum on the organic light emitting layer 304, since aluminum reacts with organic materials and is oxidized, an aluminum oxide (Al ₂ O ₃ ) layer is formed in the lower region of the cathode 306 in contact with the organic light emitting layer 304. is formed As mentioned in FIG. 3, the organic light emitting display panel includes a plurality of organic material layers and inorganic material layers. The organic material layer and the inorganic material layer generate hydrogen (H) during the process of forming the organic material layer and the inorganic material layer or in the process of aging after forming the organic material layer and the inorganic material layer.

Specifically, since the planarization layer 106, the bank layer 108, the spacer 109, and the organic light emitting layer 304 disposed below the cathode 306 are formed of organic materials, when a heat treatment process is performed, hydrogen ( H) can occur. In addition, hydrogen (H) is diffused in silicon nitride (SiNx) or silicon oxynitride (SiONx) capable of forming the first passivation layer 104 and the second passivation layer 105 disposed under the cathode 306. It can be. To deposit silicon nitride (SiNx) or silicon oxynitride (SiONx), silane (SiH ₄ ) and ammonia (NH ₃ ) are used. As silane (SiH ₄ ) and ammonia (NH ₃ ) dissociate, silicon nitride (SiNx) Alternatively, silicon oxynitride (SiONx) is formed and a large amount of hydrogen (H) is generated.

Hydrogen (H) generated from the organic material layer and the inorganic material layer is blocked by the aluminum oxide layer formed in the lower region of the cathode 306 . The aluminum oxide layer serves to block hydrogen (H) diffused in the organic material layer and the inorganic material layer. Therefore, a large amount of hydrogen (H) cannot escape and remains inside the display panel. In this case, aluminum oxide may be referred to as a hydrogen barrier material.

Hydrogen (H) remaining inside the display panel diffuses into the active layer 204 and makes the active layer 204 a conductor. When the active layer 204 becomes a conductor, the driving transistor DT loses its function as a transistor and cannot provide current to the organic light emitting diode OLED, so that a bright point defect occurs in the display panel. As mentioned above, the active layer 204 may be formed of amorphous silicon (a-Si), polycrystalline silicon (p-Si), single crystal silicon (c-Si), or oxide. Among them, the active layer 204 formed of oxide has excellent electron mobility characteristics compared to the active layer 204 formed of amorphous silicon, and has a lower production cost and uniformity than the active layer 204 formed of polycrystalline silicon. It has good uniformity and is advantageous for large size, but it is relatively affected by hydrogen (H). For example, the active layer 204 formed of oxide may be formed of indium gallium zinc oxide (IGZO), zinc oxide (ZnO), indium zinc oxide (IZO), or the like. When hydrogen (H) flows into the active layer 204 formed of oxide, it acts as a shallow donor in the active layer 204 to increase the carrier of the active layer 204, so the active layer 204 ) becomes a conductor. In this case, the transistor is always turned on and loses its role as a transistor. In order to suppress the phenomenon that the active layer 204 is conductive, an insulating film containing less hydrogen may be applied. However, since an insulating film containing less hydrogen is less effective in preventing moisture permeation, the reliability of the display panel is lowered. Occurs.

FIG. 5 is a cross-sectional view of a display panel 500 according to another exemplary embodiment of the present specification, and illustrates the driving transistor DT and the organic light emitting device OLED of FIG. 2 . In FIG. 5, overlapping descriptions with those of FIG. 3 may be omitted or briefly described.

As mentioned above, when the active layer 204 comes into contact with hydrogen (H), it reacts with hydrogen (H) to make the active layer 204 a conductor, thus losing its function as a transistor. To prevent this, a hydrogen blocking film capable of blocking hydrogen (H) may be disposed on the active layer 204 . For example, when the first passivation layer 104 is silicon oxide (SiOx), the second passivation layer 105a may be formed of aluminum oxide to serve as a hydrogen blocking layer. In addition, aluminum oxide may serve as a passivation layer because of its excellent moisture-preventing effect and electrical insulating properties. In this case, the cathode 306 may be formed of another material that does not act as a hydrogen barrier, for example, a magnesium-silver (Mg:Ag) alloy instead of aluminum (Al). The cathode 306 formed of a magnesium-silver alloy can induce hydrogen (H) generated inside the display panel to escape to the outside, but prevents hydrogen (H) from entering the active layer 204 due to diffusion. You cannot completely block it.

Referring to FIG. 5 , hydrogen (H) generated from the planarization layer 106, the bank layer 108, the spacer 109, the organic light emitting layer 304, and the encapsulation layer 400 extends to the second passivation layer 105a. Although diffused, it is blocked by the second passivation layer 105a and does not flow into the active layer 204 . Therefore, the driving transistor DT is protected from hydrogen (H) and the performance of the transistor can be maintained. That is, by disposing the hydrogen blocking film on the active layer 204, the performance of the transistor may be prevented from being reduced.

6A to 6D are cross-sectional views illustrating a method of manufacturing a passivation layer according to an embodiment of the present specification. In FIGS. 6A to 6D, overlapping descriptions with those of FIGS. 3 to 5 may be omitted or briefly described. In FIGS. 6A to 6D , the transistor formed on the substrate 100 is described by taking the driving transistor DT as an example, but is not limited thereto.

Referring to FIG. 6A , a driving transistor DT is formed on a substrate 100, and a first passivation layer 104 covering the driving transistor DT is formed through a chemical vapor deposition (CVD) method. do. The substrate 100 on which the driving transistor DT is formed, and gaseous silane (SiH ₄ ) and nitrous oxide (N ₂ O) are introduced into the chamber, and then heat is applied to form solid silicon dioxide (SiO ₂ ) on the driving transistor DT. can form Alternatively, silicon dioxide may be formed using plasma along with heat using plasma enhanced chemical vapor deposition (PECVD). In this case, hydrogen gas (H ₂ ) is formed as a side reactant, but most of the hydrogen gas (H ₂ ) is released into the air, and a small amount of hydrogen may be included on the substrate 100 . The amount of hydrogen generated during silicon dioxide formation is very small compared to the amount of hydrogen generated during silicon nitride formation. That is, the first passivation layer 104 made of silicon dioxide is formed on the driving transistor DT. Subsequently, aluminum (Al) is deposited using a sputtering method to form a second passivation layer 105a on the first passivation layer 104 . That is, an aluminum layer is formed on the first passivation layer 104 . The second passivation layer 105a has a thickness of 100 Å or more to completely block hydrogen. In addition, it is difficult to uniformly form a film with a thickness of several tens of angstroms or less due to the process capability of the spurt method. In addition, the second passivation layer 105a formed of aluminum (Al) needs to be converted into aluminum oxide (Al ₂ O ₃ ) by oxidizing it. If the second passivation layer 105a is too thick, the second passivation layer 105a Since it cannot be completely oxidized, the second passivation layer 105a is formed to a thickness of 200 Å or less. Accordingly, by forming the second passivation layer 105a to a thickness of 100 Å to 200 Å, it is possible to effectively block hydrogen and facilitate the manufacture of a hydrogen blocking film.

The lower region of the second passivation layer 105a deposited through the sputtering method contacts the first passivation layer 104 and reacts with each other. Specifically, aluminum in contact with silicon dioxide reacts to form aluminum oxide. In this case, the aluminum oxide may have a thickness of about 5 Å. In order for the second passivation layer 105a to completely block hydrogen, the second passivation layer 105a must be formed of aluminum oxide. If not converted to aluminum oxide, since the metal layer formed of aluminum remains as it is, it may have an electrical effect on the driving transistor and may be shorted to the anode formed through the second passivation layer 105a. Accordingly, the second passivation layer 105a may be entirely converted into aluminum oxide by subjecting the second passivation layer 105a to oxidation. However, aluminum oxide formed through heat treatment has a very low etch rate. Since it is very difficult to form a contact hole in aluminum oxide through an etching process, a process of forming a contact hole is first performed before heat treatment of the aluminum layer.

Referring to FIG. 6B , a first contact hole exposing the driving transistor DT is formed in the first passivation layer 104 and the second passivation layer 105a. For example, the first contact hole exposes the drain electrode 207 of the driving transistor DT so that the drain electrode 207 of the driving transistor DT and the anode can contact each other.

Referring to FIG. 6C , in the second passivation layer 105a in which the first contact hole is formed, all of the aluminum layers may be oxidized to aluminum oxide by performing heat treatment in an oxygen-sufficient atmosphere. In this case, the first passivation layer 104 formed between the driving transistor DT and the second passivation layer 105a serves to protect the driving transistor DT from the sputtering and heat treatment processes of the second passivation layer 105a. do That is, the thickness of the second passivation layer 105a serving as a hydrogen blocking film may be determined in consideration of the hydrogen blocking effect and the ease of the heat treatment process.

Referring to FIG. 6D , a planarization layer 106 is formed on the second passivation layer 105a. The planarization layer 106 forms a second contact hole in the same area as the first contact hole formed in the second passivation layer 105a through a photolithography process. Then, an anode 302 is formed on the planarization layer 106 . The anode is formed to contact the drain electrode 207 of the driving transistor DT through contact holes formed in the first passivation layer 104 , the second passivation layer 105a , and the planarization layer 106 .

The organic light emitting display panel according to the exemplary embodiment of the present specification can be described as follows.

In the organic light emitting display panel according to one embodiment of the present specification, the organic light emitting display panel includes a transistor including an active layer on a substrate, an organic light emitting element including an anode, an organic light emitting layer, and a cathode on the transistor, and a transistor A planarization layer between the organic light emitting elements, a bank layer on the planarization layer and covering a part of the anode, and blocking hydrogen generated from at least one of the organic light emitting layer, the planarization layer, and the bank layer from flowing into the active layer. A hydrogen barrier layer is included, and the hydrogen barrier layer is below the planarization layer. Therefore, by blocking the inflow of hydrogen into the active layer, the performance of the transistor may be prevented from deteriorating.

The active layer may be formed of oxide.

The hydrogen barrier layer may include aluminum oxide (Al ₂ O ₃ ).

The thickness of the hydrogen barrier layer may be determined in consideration of the hydrogen barrier effect and the ease of the heat treatment process.

The thickness of the hydrogen barrier layer may be 100 Å to 200 Å.

The cathode may include aluminum (Al).

In the organic light emitting display panel according to an exemplary embodiment of the present specification, the organic light emitting display panel includes a transistor on a substrate, an organic light emitting element including an anode, an organic light emitting layer, and a cathode on the transistor, and a gap between the transistor and the organic light emitting element. Contains hydrogen blocking material. Therefore, by blocking the inflow of hydrogen into the active layer, the performance of the transistor may be prevented from deteriorating.

The transistor may have a bottom-gate structure.

The transistor may include an active layer formed of oxide.

The active layer may be any one of IGZO, ZnO, and IZO.

On the substrate, a transistor including an active layer and a different type of active layer may be further included.

The hydrogen blocking material is aluminum oxide (Al2O3) and may be implemented in the form of a hydrogen blocking film.

The hydrogen blocking layer may cover an upper portion of the active layer of the transistor.

In the method for manufacturing an organic light emitting display panel according to an embodiment of the present specification, the method includes forming a transistor on a substrate, forming a passivation layer on the transistor, and planarizing the passivation layer. A step of forming a layer, and a step of forming an organic light emitting device on the planarization layer, and the passivation layer is formed of aluminum oxide (Al ₂ O ₃ ). Therefore, by blocking the inflow of hydrogen into the active layer, the performance of the transistor may be prevented from deteriorating.

Forming the passivation layer may include forming an aluminum (Al) layer using a sputtering method and oxidizing the aluminum (Al) layer by heat treatment.

A step of forming a first contact hole exposing the transistor in the aluminum (Al) layer may be further included before the step of heat-treating and oxidizing the aluminum (Al) layer.

Forming the planarization layer may include forming a second contact hole in the same area as the first contact hole through a photolithography process.

A step of forming an auxiliary passivation layer between the transistor and the passivation layer may be further included.

Although the embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and may be variously modified and implemented without departing from the technical spirit of the present invention. . Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. The protection scope of the present invention should be construed by the claims, and all technical ideas within the equivalent range should be interpreted as being included in the scope of the present invention.

10: data lines
20: gate lines
100: substrate
102: gate insulating film
104: first passivation layer
105, 105a: second passivation layer
106: planarization layer
108: bank layer
109: spacer
202: gate electrode
204: active layer
206: source electrode
207: drain electrode
302: anode
304: organic light emitting layer
306: cathode
400: encapsulation layer
500: display panel
600: gate driving unit
700: data driving unit
800: timing control unit
1000: display device

Claims (18)

delete delete delete delete delete delete delete delete delete delete delete delete delete forming a transistor on the substrate;
forming a passivation layer on the transistor;
forming a planarization layer on the passivation layer; and
Forming an organic light emitting device on the planarization layer,
The passivation layer is formed of aluminum oxide (Al ₂ O ₃ ),
Forming the passivation layer,
Forming an aluminum (Al) layer using a sputtering method;
Heat-treating and oxidizing the aluminum (Al) layer; and
and forming a first contact hole exposing the transistor in the aluminum (Al) layer before the heat-treating and oxidizing the aluminum (Al) layer. delete delete According to claim 14,
The forming of the planarization layer includes forming a second contact hole in the same area as the first contact hole through a photolithography process. According to claim 14,
The method of manufacturing an organic light emitting display panel further comprising forming an auxiliary passivation layer between the transistor and the passivation layer.

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