Light emitting display apparatus and method of manufacturing the same

A light emitting display apparatus includes a passivation layer on a thin film transistor, a light emitting diode on the passivation layer, the light emitting diode having an anode, a light emitting layer on the anode, and a cathode on the light emitting layer, and a hydrogen absorbing layer on the light emitting diode, the hydrogen absorbing layer including an inorganic material having a mass percentage of 0.08% to 50%.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Korean Patent Application No. 10-2018-0101229 filed on Aug. 28, 2018 and Korean Patent Application No. 10-2018-0173630 filed on Dec. 31, 2018, in the Korean Intellectual Property Office, the disclosures of all these applications are incorporated herein by reference into the present application.

BACKGROUND

Technical Field

The present disclosure relates to a light emitting display apparatus and a method of manufacturing the same, and more particularly, to a light emitting display apparatus which is capable of reducing a defect of a thin film transistor due to hydrogen and a method of manufacturing the same.

Description of the Related Art

The light emitting display apparatus is a self-emitting display apparatus so that a separate light source is not necessary, which is different from the liquid crystal display apparatus. Therefore, the light emitting display apparatus can be manufactured to have light weight and small thickness. Further, since the light emitting display apparatus is driven at a low voltage, it is advantageous not only in terms of power consumption, but also in the implementation of colors, the response speed, the viewing angle, and the contrast ratio, so that the light emitting display apparatus is being studied as next generation displays.

In the light emitting display apparatus, a light emitting diode disposed in each sub pixel is driven to emit light. In this case, in order to independently drive the light emitting diodes of the sub pixels, one or more thin film transistors (TFT) which are electrically connected to the light emitting diode are disposed in each sub pixel.

The thin film transistor includes a gate electrode, a source electrode, a drain electrode, and a semiconductor layer. The source electrode and the drain electrode are in contact with the semiconductor layer and the gate electrode is disposed so as to overlap the semiconductor layer. When a gate voltage of a predetermined voltage or higher is applied to the gate electrode of the thin film transistor, a channel is formed in the semiconductor layer so as to allow the current to flow between the source electrode and the drain electrode. As described above, the thin film transistor has a switching characteristic and the switching characteristic can be determined by various factors. For example, when a material of the semiconductor layer is deformed, mobility of the thin film transistor is changed so that the switching characteristic of the thin film transistor can be changed.

The light emitting display apparatus includes a passivation layer which protects the light emitting diode from moisture or oxygen penetrating the light emitting diode. The passivation layer is formed on the light emitting diode to protect the light emitting diode.

The passivation layer is formed by, for example, a chemical vapor deposition (CVD) method using silane (SiH4) and ammonia (NH3). During the process of forming the passivation layer by the chemical vapor deposition method, a small amount of hydrogen can be generated from silane and ammonia. Therefore, the hydrogen generated during the process of forming the passivation layer is diffused to the passivation layer to be included in the passivation layer. The residual hydrogen included in the passivation layer can move in the light emitting diode. When the residual hydrogen is diffused to the semiconductor layer of the thin film transistor to react with the semiconductor layer, the characteristic of the thin film transistor can be modified. Therefore, the hydrogen generated during the process of forming the passivation layer can degrade not only the performance of the thin film transistor, but also the performance of the light emitting display apparatus.

SUMMARY OF THE INVENTION

In order to solve the problem in that hydrogen generated when the passivation layer of the light emitting display apparatus is formed remains in the light emitting display apparatus and the residual hydrogen is diffused towards the thin film transistor so that the characteristic of the thin film transistor is modified to degrade the performance of the light emitting display apparatus, inventors of the present disclosure invented a new structure of a light emitting display apparatus which is capable of absorbing the hydrogen included in the passivation layer and a method of manufacturing the same.

Therefore, an object to be achieved by the present disclosure is to provide a light emitting display apparatus which suppresses the degradation of the performance of the thin film transistor by absorbing hydrogen remaining in the passivation layer and a method of manufacturing a light emitting display apparatus.

Further, another object to be achieved by the present disclosure is to provide a light emitting display apparatus having a structure which is capable of removing hydrogen in a passivation layer without providing a separate device for removing hydrogen generated during the process of forming a passivation layer and a method of manufacturing a light emitting display apparatus.

According to an aspect of the present disclosure, a light emitting display apparatus includes a passivation layer on a thin film transistor, a light emitting diode on the passivation layer and includes an anode, a light emitting layer on the anode, and a cathode on the light emitting layer, and a hydrogen absorbing layer on the light emitting diode and includes an inorganic material having a mass percenatage of 0.08% to 50%.

According to another aspect of the present disclosure, a light emitting display apparatus includes a lower substrate, a thin film transistor on the lower substrate and includes an oxide semiconductor layer, a passivation layer on the thin film transistor, a light emitting diode on the thin film transistor and the passivation layer and includes an anode, a light emitting layer on the anode, and a cathode on the light emitting layer, and a seal in contact with the light emitting diode, the seal including a hydrogen absorbing filler.

According to another aspect of the present disclosure, a light emitting display apparatus includes a lower substrate including a thin film transistor and a light emitting diode, an upper substrate on the lower substrate, an adhesive layer between the lower substrate and the upper substrate, and the adhesive layer being on the thin film transistor, and a seal between the adhesive layer and the upper substrate, the seal including a hydrogen absorbing filler in contact with the adhesive layer.

According to another aspect of the present disclosure, a method of manufacturing a light emitting display apparatus includes: forming a thin film transistor on a lower substrate, forming a passivation layer on the thin film transistor, forming a light emitting diode including an anode, a light emitting layer, and a cathode on the passivation layer, and forming a hydrogen absorbing layer including a hydrogen absorbing filler on the light emitting diode.

Other detailed matters of the embodiments are included in the detailed description and the drawings.

According to the present disclosure, a hydrogen absorbing layer which absorbs hydrogen remaining in a passivation layer which can modify a characteristic of a thin film transistor is configured to suppress the degradation of the performance of the thin film transistor.

DETAILED DESCRIPTION OF THE EMBODIMENTS

When the position relation between two parts is described using the terms such as “on,” “above,” “below,” and “next,” one or more parts can be positioned between the two parts unless the terms are used with the term “immediately” or “directly.”

When an element or layer is disposed “on” another element or layer, another layer or another element can be interposed directly on the other element or therebetween.

Although the terms “first,” “second,” and the like are used for describing various components, these components are not confined by these terms. These terms are merely used for distinguishing one component from the other components. Therefore, a first component to be mentioned below can be a second component in a technical concept of the present disclosure.

Hereinafter, a light emitting display apparatus according to embodiments of the present disclosure will be described in detail with reference to accompanying drawings.

FIG. 1Aillustrates a light emitting display apparatus according to an embodiment of the present disclosure andFIG. 1Bis a cross-sectional view taken along the line I-I′ ofFIG. 1A.

For example, inFIG. 1A, the line I-I′ is disposed at one side of a light emitting display apparatus100so thatFIG. 1Bis a cross-sectional view taken along one side of the light emitting display apparatus100.

With reference toFIGS. 1A and 1B, the light emitting display apparatus100includes a lower substrate110, a gate insulating layer120, a thin film transistor130, a passivation layer140, a light emitting diode150, an over coating layer160, a bank170, a hydrogen absorbing layer180, a side seal member190, and an upper substrate119.

The passivation layer140includes a first passivation layer141which covers the thin film transistor130and a second passivation layer142which covers the light emitting diode150.

For reference, for the convenience of description, inFIG. 1A, only the passivation layer140and the hydrogen absorbing layer180of the light emitting display apparatus100are illustrated.

With reference toFIG. 1A, the light emitting display apparatus100includes a plurality of pixels PX. Each pixel PX includes a plurality of sub pixels SP. The sub pixel SP can be a basic emission unit which configures the light emitting display apparatus100and each of the sub pixels SP which configures one pixel PX emits light having different colors. As illustrated inFIG. 1A, the sub pixel SP can include a red sub pixel, a green sub pixel, a blue sub pixel, and a white sub pixel or include only a red sub pixel, a green sub pixel, and a blue sub pixel.

Further, with reference toFIG. 1B, the display apparatus100according to an embodiment of the present disclosure can include a sub pixel SP having a color-filter on transistor (COT) structure. For example, colors of the sub pixels SP can be implemented by a color filter CF disposed on an upper layer of the thin film transistor130so as to overlap the emission area of the sub pixel SP. For example, when the light emitting diode150emits white light, a red color filter CF is disposed in an area corresponding to the emission area of the light emitting diode150to implement a red sub pixel SP. Further, a green color filter CF is disposed in an area corresponding to the emission area of the light emitting diode150to implement a green sub pixel SP. Further, a blue color filter CF is disposed in an area corresponding to the emission area of the light emitting diode150to implement a blue sub pixel SP. Furthermore, no color filter CL is disposed in an area corresponding to the emission area of the light emitting diode150to implement a white sub pixel SP. Details of the color filter CF will be described below.

The thin film transistor130including a semiconductor layer131, a gate electrode132, a source electrode133, and a drain electrode134is formed on the lower substrate110which is formed of an insulating material. For example, the semiconductor layer131is formed on the lower substrate110and the gate insulating layer120which insulates the gate electrode132from the semiconductor layer131is disposed on the semiconductor layer131and the lower substrate110. The gate electrode132is formed on the gate insulating layer120and the source electrode133and the drain electrode134are formed on the semiconductor layer131and the gate insulating layer120. The source electrode133and the drain electrode134are in contact with the semiconductor layer131to be electrically connected to the semiconductor layer131and are formed on a partial area of the gate insulating layer120. In the present specification, for the convenience of description, among various thin film transistors which can be included in the light emitting display apparatus100, only a driving thin film transistor is illustrated, but a switching thin film transistor can also be included. Further, in the present specification, even though it is described that the thin film transistor130has a coplanar structure, a thin film transistor having an inverted staggered structure can also be used.

The semiconductor layer131can be configured by an oxide semiconductor or an amorphous semiconductor. The amorphous semiconductor can be configured by amorphous silicon. The semiconductor layer can be configured by polycrystalline silicon, but is not limited thereto. The polycrystalline silicon has a better mobility than that of the amorphous silicon and has low power consumption and excellent reliability so as to be applied to the driving thin film transistor in the pixel.

The first passivation layer141is conformally disposed on an upper surface of the thin film transistor130. For example, the first passivation layer141can be formed along a shape of the upper surface of the thin film transistor130. The first passivation layer141is formed to cover the thin film transistor130, and is also disposed on the entire surface of the lower substrate110on which the thin film transistor130is disposed. Further, with reference toFIG. 1A, the first passivation layer141is formed so as to overlap all the plurality of sub pixels SP.

The first passivation layer141can be formed to have a thickness of 10 μm or smaller, for example, can be formed to have a thickness of 0.5 μm, but is not limited thereto.

As described above, the first passivation layer141can be disposed so as to cover the thin film transistor130. The first passivation layer141can protect the thin film transistor130from oxygen or moisture from the outside of the light emitting display apparatus100. Various organic layers or inorganic layers can be used for the first passivation layer141. The first passivation layer141can be formed by various structures such as a single deposition structure of an organic layer, a single deposition structure of an inorganic layer, or an alternative deposition structure of organic layer/inorganic layer. For example, the first passivation layer141can be formed of silicon nitride SiNxor silicon oxide SiOx, but is not limited thereto.

The color filter CF can be disposed on the first passivation layer141so as to overlap the emission area of the sub pixel SP. Since the color filter CF is disposed in the emission area of the sub pixel SP, the color filter CF is disposed on the upper layer of the thin film transistor130, but disposed not to overlap the thin film transistor130.

Each color filter CF can include a red color filter CF including a red pigment, a green color filter CF including a green pigment, and a blue color filter including a blue pigment so as to implement colors of the sub pixels SP.

In order to form a color filter CF, the red color filter CF, the green color filter CF, and the blue color filter CF need to be subjected to a coating process, an exposure process, a development process, and a post-bake process.

Among these processes, during the post-back process, a pigment layer for forming the color filter CF is heated so that gases including hydrogen included in the pigment layer are discharged.

In spite of the post-bake process, hydrogen can remain in the color filter CF. Therefore, the residual hydrogen included in the color filter CF can move in the light emitting display apparatus100and is diffused to the semiconductor layer131of the thin film transistor130so that the characteristic of the thin film transistor130can be changed. For example, the semiconductor layer131can absorb hydrogen. When the semiconductor layer131absorbs hydrogen, a threshold voltage Vthof the thin film transistor130is shifted so that the mobility of the thin film transistor130can be increased. Therefore, the characteristic of the thin film transistor130is changed so that the performance is degraded, spots or bright spots are generated, and the luminance irregularity is caused. Therefore, the hydrogen generated during the process of forming the color filter CF can degrade not only the performance of the thin film transistor130, but also the performance of the light emitting display apparatus100so that it is necessary to remove the residual hydrogen in the color filter CF.

The over coating layer160is disposed on the gate insulating layer120, the thin film transistor130, the first passivation layer141, and the color filter CF. The over coating layer160is formed to cover the thin film transistor130and the first passivation layer141and planarizes the upper portion of the thin film transistor130and the first passivation layer141. The over coating layer160can be formed of an insulating material.

A light emitting diode150including an anode151, a light emitting layer152, and a cathode153and a bank170are formed on the over coating layer160. For example, the anode151which supplies holes to the light emitting layer152is formed on an upper surface of the over coating layer160, the light emitting layer152is formed on the anode151, and the cathode153which supplies electrons to the light emitting layer152is formed on the light emitting layer152.

When the light emitting display apparatus100is a bottom emission type, for example, the anode151can include a transparent conductive layer formed of a transparent conductive oxide (hereinafter, abbreviated as TCO) such as indium tin oxide (ITO) or indium zinc oxide (IZO), or ZnO. Further, the cathode153can be formed of a metal material having a low optical transmittance.

When the light emitting display apparatus100is a top emission type, the anode151can include a reflective layer and a transparent conductive layer which is formed of a transparent conductive oxide on the reflective layer. Further, the cathode153can be formed with a thin metal material having a low work function or formed of a transparent conductive oxide. When the cathode153is formed of a transparent conductive oxide, a multiple layer can be disposed between the cathode153and the light emitting layer152so that the electrons move through the cathode153. For example, a metal-doped layer can be disposed between the light emitting layer152and the cathode153. Further, an organic buffer layer can be additionally disposed between the light emitting layer152and the metal-doped layer.

The bank170is formed to cover the side of the anode151to define an emission area of each sub pixel SP.

For example, as illustrated inFIG. 1B, the bank170is in contact with an upper portion of the first passivation layer141and is formed so as to enclose the side of the anode151and the side of the over coating layer160. By doing this, the bank170can block the entering and diffusion of the moisture and impurities from the side of the over coating layer160.

The second passivation layer142is conformally disposed on an outer surface of the light emitting diode150. For example, the second passivation layer142can be formed along shapes of an upper surface and a side of the cathode153. For example, the second passivation layer142can be formed not only to enclose the side of the cathode153, but also to be in contact with the first passivation layer141. Further, with reference toFIG. 1A, the second passivation layer142is formed so as to overlap all the plurality of sub pixels SP.

Further, the second passivation layer142can also be formed to have a thickness of 10 μm or smaller, for example, can be formed to have a thickness of 0.5 μm, but is not limited thereto.

As described above, the second passivation layer142can be disposed so as to cover the light emitting diode150. The second passivation layer142can protect the light emitting diode150from oxygen or moisture from the outside of the light emitting display apparatus100. Various organic layers or inorganic layers can be used for the second passivation layer142. The second passivation layer142can be formed by various structures such as a single deposition structure of an organic layer, a single deposition structure an inorganic layer, or an alternative deposition structure of an organic layer/an inorganic layer. For example, the second passivation layer142can be formed of silicon nitride SiNxor silicon oxide SiOx, but is not limited thereto.

The passivation layer140including the first passivation layer141and the second passivation layer142is formed by a chemical vapor deposition (CVD) method using gas containing hydrogen (for example, silane (SiH4) and ammonia (NH3)). Therefore, during the process of forming the passivation layer140, hydrogen can be generated, and the generated hydrogen is diffused to the passivation layer140to be included in the passivation layer140. Here, hydrogen may refer to the element of hydrogen, and can include hydrogen atom (H) and hydrogen molecule (H2). For example, the hydrogen remaining in the passivation layer140can be diffused in all directions. The diffusion can proceed according to a concentration gradient, for example, a chemical potential. Therefore, the residual hydrogen included in the passivation layer140can move in the light emitting display apparatus100and is diffused to the semiconductor layer131of the thin film transistor130so that the characteristic of the thin film transistor130can be changed. For example, the semiconductor layer131can absorb hydrogen. When the semiconductor layer131absorbs hydrogen, a threshold voltage Vthof the thin film transistor130is shifted so that the mobility of the thin film transistor130can be increased. Therefore, the characteristic of the thin film transistor130is changed so that the performance is degraded, spots or bright spots are generated, and the luminance irregularity is caused. Therefore, the hydrogen generated during the process of forming the passivation layer140can degrade not only the performance of the thin film transistor130, but also the performance of the light emitting display apparatus100so that it is necessary to remove the residual hydrogen in the passivation layer140. Further, the characteristic of the thin film transistor130is changed due to the residual hydrogen in the passivation layer140depending on the material of the upper substrate119so that bright spots can be generated.

Therefore, in order to remove the hydrogen remaining in the color filter CF and the passivation layer140, a hydrogen absorbing layer180can be disposed to cover the upper surface and the side of the second passivation layer142. For example, the hydrogen absorbing layer180can be in contact not only with the upper surface of the second passivation layer142, but also with the side of the second passivation layer142to cover an outer surface of the second passivation layer142to be planarized. Further, one side of (or one portion of) a lower surface of the hydrogen absorbing layer180can be in contact with the first passivation layer141.

As described above, since the hydrogen absorbing layer180is formed to be in contact with the first passivation layer141and the second passivation layer142, a contact area of the hydrogen absorbing layer80and the first passivation layer141and the second passivation layer142can be increased. Therefore, the hydrogen absorbing layer180can effectively absorb the hydrogen included in the first passivation layer141and the second passivation layer142.

The hydrogen absorbing layer180can be formed to have a thickness of 5000 Å or smaller, for example, can be formed to have a thickness of 50 μm at maximum, but is not limited thereto. The hydrogen absorbing layer180can be a seal and is not limited to the term. The seal can be disposed on the entire light emitting diode.

The seal can be formed based on a curable resin or a photo curable resin. For example, the curable resin can be epoxy resin, but is not limited thereto. For example, the photo curable resin can be polyolefin resin, but is not limited thereto.

Further, one side of the hydrogen absorbing layer180and one side of the upper substrate119can further include a side seal member190which edges the side of the light emitting display apparatus100. For example, the side seal member190can be in contact with one side of the upper surface of the first passivation layer141, one side of the hydrogen absorbing layer180, and one side of the upper substrate119. Further, the side seal member190can minimize the moisture permeation at the side. To this end, the side seal member190can be formed of, for example, an acryl, urethane, and silicon based curable material, but is not limited thereto.

The above-described hydrogen absorbing layer180can include an inorganic material FT which absorbs or adsorbs hydrogen (for example, hydrogen atom (H) and hydrogen molecule (H2)) or moisture to serve as a filter to absorb the residual hydrogen in the color filter CF and the passivation layer140. The inorganic material FT can be a hydrogen absorbing filler and absorb or adsorb hydrogen or moisture. The filler can be powder or particle, and is not limited to this terminology or form. For example, the filler can be flakes, nodules or other forms. The inorganic material FT of the hydrogen absorbing layer180can include at least one of a metal, a mixture including a metal, and a compound including a metal. For example, the hydrogen absorbing layer180can be configured to include a metal, a mixture of metal, a compound of metal, a combination of a metal and a mixture of metal, a combination of a metal and a compound of metal, a combination of a mixture of metal and a compound of metal, or a combination of a metal, a mixture of metal, and a compound of metal. Here, the metal can include one or more of an alkali metal, an alkaline earth metal, a rare earth metal, a titanium (Ti) Ground metal, a transition metal, and a post transition metal. However, embodiments are not limited thereto. For, example, “post transition metals” may refer to the metal elements of in the 13th group to 15th group of the element periodic table. Further, the metal can be a particle having a diameter of several to several tens nanometer (nm). For example, the metal can be a particle having a diameter of 100 nm or smaller, but is not limited thereto.

The inorganic material FT of the hydrogen absorbing layer180can absorb hydrogen in various manners. For example, the inorganic material FT of the hydrogen absorbing layer180can absorb hydrogen through a chemical reaction or absorb the hydrogen by trapping the hydrogen in a gap between the inorganic materials FT.

The inorganic material FT of the hydrogen absorbing layer180reacts with the remaining hydrogen in the color filter CF and the passivation layer140to generate a hydrogen compound. Therefore, the hydrogen compound obtained by the reaction of the inorganic material FT of the hydrogen absorbing layer180with the remaining hydrogen in the color filter CF and the passivation layer140can be included in the hydrogen absorbing layer180. For example, the hydrogen absorbing layer180can include not only the inorganic material FT, but also the hydrogen compound. The hydrogen compound generated in the hydrogen absorbing layer180can be formed by a reaction represented by the following Chemical Formula 1.
Me+(X/2)H2→MeHx[Chemical Formula 1]

[Chemical Formula 1] is a chemical formula which explains a process in which the inorganic material FT of the hydrogen absorbing layer180reacts with the remaining hydrogen to generate a hydrogen compound MeHx. Here, Me refers to a metal. However, not only the metal, but also a metal compound or a metal mixture can react with hydrogen as represented in Chemical Formula 1 to form a hydrogen compound. In embodiments, the hydrogen compound can be one or more metal halides or halides.

Therefore, when the inorganic material FT of the hydrogen absorbing layer180reacts with the residual hydrogen in the color filter CT and the passivation layer140to generate a hydrogen compound, an energy is generated or absorbed. Such an energy is referred to as a hydrogen adsorption energy.

In this regard, in Table 1, when a temperature is 298 K, a hydrogen adsorption energy in accordance with a type of metal is represented. In this regard, when the hydrogen adsorption energy is positive, it means that when metal and hydrogen which are inorganic materials FT are adsorbed, metal and hydrogen generate heat and spontaneously react. When the hydrogen adsorption energy is negative, it means that when metal and hydrogen which are inorganic materials FT are adsorbed, metal and hydrogen absorb heat and involuntarily react with each other.

For example, it means that the hydrogen adsorption reaction is more spontaneously generated as the hydrogen adsorption energy is lower so that the adsorption reaction with hydrogen satisfactorily occurs in the order of vanadium (V), copper (Cu), iron (Fe), nickel (Ni), and palladium (Pd).

In Table 1, the hydrogen adsorption energy at a temperature of 298 K is represented. However, a process temperature is generally higher than 300 K, so that the hydrogen adsorption energy can be lower than that described in Table 1.

For example, the inorganic material FT included in the hydrogen absorbing layer180can include one or more of a metal such as thorium (Th), zirconium (Zr), vanadium (V), palladium (Pd), titanium (Ti), magnesium (Mg), nickel (Ni), tin (Sn), platinum (Pt), chrome (Cr), silver (Ag), aluminum (Al), copper (Cu), gold (Au), cobalt (Co), and iron (Fe), lanthanum-nickel (La—Ni), lanthanum-nickel-aluminum (La—Ni—Al), nickel-magnesium (Ni—Mg), iron-titanium (Fe—Ti), and titanium-manganese (Ti—Mn), but is not limited thereto.

In addition to the inorganic material FT, the material included in the hydrogen absorbing layer180can be at least one of carbon nano tube (CNT) and graphene, but is not limited thereto.

The semiconductor layer131included in the light emitting display apparatus according to the embodiment of the present disclosure can be formed by an oxide semiconductor. The oxide semiconductor has excellent mobility and uniformity. The semiconductor layer can be configured by the oxide semiconductor such as an indium tin gallium zinc oxide (InSnGaZnO) based material which is a quaternary metal oxide, an indium gallium zinc oxide (InGaZnO) based material, an indium tin zinc oxide (InSnZnO) based material, an indium aluminum zinc oxide (InAlZnO) based material, a tin gallium zinc oxide (SnGaZnO) based material, an aluminum gallium zinc oxide (AlGaZnO) based material, a tin aluminum zinc oxide (SnAlZnO) based material which are ternary metal oxides, an indium zinc oxide (InZnO) based material, a tin zinc oxide (SnZnO) based material, an aluminum zinc oxide (AlZnO) based material, a zinc magnesium oxide (ZnMgO) based material, a tin magnesium oxide (SnMgO) based material, an indium magnesium oxide (InMgO) based material, an indium gallium oxide (InGaO) based material which are bimetallic oxides, an indium oxide (InO) based material, a tin oxide (SnO) based material, and a zinc oxide (ZnO) based material, but a composition ratio of individual elements is not limited.

As described above, when the semiconductor layer131is an oxide semiconductor, the residual hydrogen included in the color filter CF and the passivation layer140is diffused to the semiconductor layer131configured by the oxide semiconductor. Therefore, the semiconductor layer131configured by the oxide semiconductor is reduced so that the concentration of electrons is increased. Therefore, in the semiconductor layer131configured by the oxide semiconductor, a channel through which unintended leakage current can flow can be formed due to the high electron concentration to cause bright spots. Therefore, the light emitting display apparatus according to the embodiment of the present disclosure removes the residual hydrogen included in the color filter CF and the passivation layer140so that the problem caused when the semiconductor layer131is configured by the oxide semiconductor can be solved. For example, even though the hydrogen is diffused from the color filter CF and the passivation layer140, the diffused hydrogen is absorbed by the inorganic material FT of the hydrogen absorbing layer180so that the hydrogen need not affect the semiconductor layer131configured by the oxide semiconductor.

Further, a seal including the hydrogen absorbing layer180or a hydrogen absorbing filler is configured so that the problem in that the bright spot is generated depending on the material of the upper substrate can be solved.

The upper substrate119can be a metal, a plastic film, and glass, but is not limited thereto. For example, the metal can be iron-nickel (Fe—Ni), but is not limited thereto. Therefore, even though the material of the upper substrate119is changed, the defect such as the bright spot by the residual hydrogen is reduced, so that the degree of freedom for a material of the upper substrate119can be improved.

FIG. 2is a graph for explaining a change in a threshold voltage of a thin film transistor of a light emitting display apparatus according to an embodiment of the present disclosure. The inorganic material FT which absorbs hydrogen can be included with a mass percentage of 0.08% to 50% with respect to a total mass of the hydrogen absorbing layer180including an adhesive layer. For example, the inorganic material FT can include a mass percentage of 0.08% to 50% with respect to a total mass of the adhesive layer and the hydrogen absorbing layer ofFIG. 3.

For example, a mass percentage of the inorganic material FT which absorbs hydrogen included in the hydrogen absorbing layer180can be 0.08% to 50%.

In this regard, when the mass percentage of the inorganic material FT which absorbs hydrogen is lower than 0.08%, the threshold voltage Vthof the thin film transistor130has a negative change amount with respect to a normal range of 1 V to −1 V, so that the thin film transistor130is not controlled, but is always turned on to cause the bright spots in the display apparatus100. In contrast, when the mass percentage of the inorganic material FT which absorbs hydrogen is 0.08% or higher, the threshold voltage Vthof the thin film transistor130is 1 V to −1 V which is a normal range, so that the thin film transistor130is normally controlled and no bright spot is generated in the display apparatus100.

With reference toFIG. 2, for example, as described in a comparative example, when the mass percentage of the inorganic material FT which absorbs hydrogen is lower than 0.08%, the threshold voltage Vthof the thin film transistor130is −5.14 V which is out of a normal range of 1 V to −1V, so that the thin film transistor130is not controlled, but is always turned on to cause the bright spots in the display apparatus100. In contrast, according to an example, when the mass percentage of the inorganic material FT which absorbs hydrogen is 0.08%, the threshold voltage Vthof the thin film transistor130is 1 V which is within a normal range, so that the thin film transistor130is normally controlled and no bright spot is generated in the display apparatus.

When a mass percentage of the inorganic material FT which absorbs hydrogen is 50% or higher, adhesiveness of the hydrogen absorbing layer180including an adhesive layer is reduced so that the lower substrate110and the upper substrate119which is opposite to the lower substrate110are not stably bonded. Therefore, mechanical reliability can be degraded. Therefore, the inorganic material FT which absorbs hydrogen can be included with a mass percentage of 0.08% to 50% with respect to a total mass of the hydrogen absorbing layer180including the adhesive layer.

The inorganic material FT in the hydrogen absorbing layer180can transmit light which is incident onto the hydrogen absorbing layer180. For example, a transmittance of the hydrogen absorbing layer180with respect to light incident onto the hydrogen absorbing layer180can be 50% or higher. For example, a transmittance of the hydrogen absorbing layer180with respect to light incident onto the hydrogen absorbing layer180can be 70% or higher. The light transmitting characteristic of the hydrogen absorbing layer180can be advantageous to ensure the transmittance in the top emission type light emitting display apparatus and improve a luminous efficiency.

Further, the hydrogen absorbing layer180can further include the adhesive layer to bond the lower substrate110and the upper substrate119which is opposite to the lower substrate110. The hydrogen absorbing layer and the adhesive layer can be a seal, but is not limited to this terminology or form.

The hydrogen which is generated during the process of forming the color filter CF and the passivation layer140to remain in the color filter CF and the passivation layer140can move in the light emitting display apparatus100. The semiconductor layer131absorbs the residual hydrogen to degrade the performance of the thin film transistor130. Therefore, in the light emitting display apparatus100according to the embodiment of the present disclosure, the hydrogen absorbing layer180which includes an inorganic material which absorbs hydrogen is disposed to be in contact with an upper surface of the cathode153of the light emitting diode150. Therefore, the hydrogen absorbing layer180reacts with the residual hydrogen in the color filter CF and the passivation layer140to form a hydrogen compound. Therefore, the hydrogen absorbing layer180absorbs or adsorbs the residual hydrogen which moves from the passivation layer140to the thin film transistor130. Therefore, the light emitting display apparatus100can suppress the performance degradation of the thin film transistor130due to the residual hydrogen which moves through the hydrogen absorbing layer180, reduce spots or bright spots, and reduce the luminance irregularity.

In some embodiments, the hydrogen absorbing layer180can further include a getter in addition to the inorganic material which absorbs hydrogen. The getter can be particles which absorb moisture and gas.

Further, in some embodiments, the inorganic material which absorbs hydrogen can also be included in the over coating layer160disposed on the thin film transistor130and the bank170disposed on the over coating layer160.

The inorganic material which absorbs hydrogen is also included in the over coating layer160and the bank170so that the inorganic material included in the over coating layer160and the bank170absorbs hydrogen through chemical reaction or absorbs the hydrogen by trapping the hydrogen in a gap between inorganic materials.

Therefore, the residual hydrogen which moves from the passivation layer140to the thin film transistor130can be more efficiently absorbed so that the performance degradation of the thin film transistor130due to the moving residual hydrogen can be effectively suppressed.

FIG. 3is a schematic cross-sectional view of one sub pixel of a light emitting display apparatus according to another embodiment of the present disclosure. A hydrogen absorbing layer283and an adhesive layer281of a light emitting display apparatus200ofFIG. 3are different from those of the light emitting display apparatus100ofFIG. 1B, but other components are substantially the same so that a redundant description will be omitted.

With reference toFIG. 3, the adhesive layer281is conformally disposed on an outer surface of the second passivation layer142. For example, the adhesive layer281can be formed along shapes of an upper surface and a side of the second passivation layer142. The adhesive layer281can be formed not only to cover the second passivation layer142, but also to cover one side of the first passivation layer141.

Here, the adhesive layer281bonds the lower substrate110and the upper substrate119which is opposite to the lower substrate110. Therefore, the adhesive layer281can include an adhesive material. For example, the adhesive layer281can be formed of a liquid type or a film type adhesive material. For example, the adhesive layer281can be formed of resin, epoxy, or acrylic material, but is not limited thereto.

The hydrogen absorbing layer283covers an outer surface of the adhesive layer281and an upper surface of the hydrogen absorbing layer283can be formed to be flat while being in contact with the upper substrate119.

Therefore, the hydrogen absorbing layer283is formed to be separated and independent from the adhesive layer281so that the contact characteristic with the cathode153of the light emitting diode150which is in contact with the adhesive layer281can be improved. Therefore, the light emitting diode150and the adhesive layer281can be more durably bonded to each other so that the inorganic material included in the hydrogen absorbing layer283can absorb hydrogen through a chemical reaction or absorb the hydrogen by trapping the hydrogen in a gap between the inorganic materials.

Accordingly, the residual hydrogen which moves from the color filter CF and the passivation layer140to the thin film transistor130can be more efficiently absorbed so that the performance degradation of the thin film transistor130due to the moving residual hydrogen can be effectively suppressed.

FIG. 4is a flowchart for explaining a method of manufacturing a light emitting display apparatus according to an embodiment of the present disclosure. Hereinafter, a process order of forming a first passivation layer141, a color filter CF, a second passivation layer142, and a hydrogen absorbing layer180will be mainly described with reference toFIGS. 1A and 1B.

First, the thin film transistor130is formed on the lower substrate110in step S310.

With reference toFIG. 1B, the semiconductor layer131is formed on the lower substrate110, the gate insulating layer120is formed on the semiconductor layer131and the lower substrate110, the gate electrode132is formed on the gate insulating layer120, and the source electrode133and the drain electrode134are formed on the semiconductor layer131and the gate insulating layer120to form the thin film transistor130.

Next, the first passivation layer141is formed on the thin film transistor130in step S320.

The first passivation layer141is formed by a chemical vapor deposition (CVD) method using silane and ammonia. Therefore, hydrogen can be generated from silane and ammonia used during the process of forming the first passivation layer141by the chemical vapor deposition method. The generated hydrogen can be diffused to be included in the first passivation layer141.

Next, the color filter CF is formed on the first passivation layer141in step S330.

In order to form the color filter CF, the red color filter CF, the green color filter CF, and the blue color filter CF are subjected to a coating process, an exposure process, a development process, and a post-bake process. Among these processes, during the post-bake process, a pigment layer for forming the color filter CF is heated so that gases including hydrogen included in the pigment layer are discharged. In spite of the post-bake process, hydrogen can remain in the color filter CF.

Next, the anode151is formed on the color filter CF, the light emitting layer152is formed on the anode151, and the cathode153is formed on the light emitting layer152, sequentially, to form the light emitting diode150in step S340.

With reference toFIG. 1B, the anode151is electrically connected to the drain electrode134through a contact hole in the over coating layer160, the bank170is formed so as to cover a part of both ends of the anode151, and the light emitting layer152and the cathode153are disposed on the anode151and the bank170to form the light emitting diode150.

Next, the second passivation layer142is formed on the light emitting diode150in step S350.

The second passivation layer142is also formed by a chemical vapor deposition (CVD) method using silane and ammonia. Therefore, hydrogen can be generated from silane and ammonia used during the process of forming the second passivation layer142by the chemical vapor deposition method. The generated hydrogen can be diffused to be included in the second passivation layer142. The second passivation layer142can be omitted.

Next, the hydrogen absorbing layer180is formed on the second passivation layer142in step S360.

With reference toFIG. 1B, the hydrogen absorbing layer180is formed so as to cover the upper surface and the side of the second passivation layer142. Here, the hydrogen absorbing layer180includes an inorganic material which absorbs hydrogen. When the second passivation layer142is not configured, the hydrogen absorbing layer180can be disposed along the upper surface and the side of the light emitting diode150. For example, the hydrogen absorbing layer180can be disposed so as to be in contact with the upper surface of the cathode153of the light emitting diode150. For example, the hydrogen absorbing layer180can be disposed so as to be in contact with the upper surface and the side of the cathode153of the light emitting diode150.

The hydrogen absorbing layer180can be formed by performing a chemical vapor deposition method, a sputtering method, or a thermal evaporation method on the inorganic material. Specifically, as illustrated inFIG. 1B, when the hydrogen absorbing layer180is formed so as to be in contact with the upper surface of the second passivation layer142, the hydrogen absorbing layer180can be formed by performing a chemical vapor deposition method, a sputtering method, or a thermal evaporation method on the inorganic material on the upper surface of the second passivation layer142.

In some embodiments, the hydrogen absorbing layer180can also be formed by dispersing or doping the inorganic material into the organic material. For example, the organic material is disposed on the second passivation layer142and the inorganic material which absorbs hydrogen is dispersed or doped into the organic material to form the hydrogen absorbing layer180. Here, the organic material can be the same material as the material used for the light emitting layer152. The hydrogen absorbing layer180can be formed to have a thickness of 5000 Å or smaller, for example, can be formed to have a thickness of 50 μm, but is not limited thereto.

In the method of manufacturing a light emitting display apparatus according to the embodiment of the present disclosure, the residual hydrogen can be efficiently removed through the hydrogen absorbing layer180without using additional equipment or cost so that the residual hydrogen in the color filter CF and the passivation layer140does not affect the mobility of the thin film transistor130. For example, the hydrogen absorbing layer180is formed using a chemical vapor deposition method, a sputtering method, or a thermal evaporation method, so that the light emitting display apparatus100can include a configuration which can absorb the residual hydrogen in the color filter CF and the passivation layer140without excessive additional cost.

An embodiment of the present disclosure can also be described as follows:

According to an aspect of the present disclosure, a light emitting display apparatus includes a passivation layer on a thin film transistor and includes hydrogen, a light emitting diode on the passivation layer, the light emitting diode having an anode, a light emitting layer on the anode, and a cathode on the light emitting layer, and a hydrogen absorbing layer on the light emitting diode, the hydrogen absorbing layer including an inorganic material having a mass percentage of 0.08% to 50%.

The inorganic material can include at least one of a metal, a mixture including the metal, and a compound including the metal.

The metal can include one or more of: an alkali metal, an alkaline earth metal, a rare earth metal, a titanium (Ti) Group metal, a transition metal, and a post transition metal.

The metal can be a particle having a diameter smaller than 100 nm.

The inorganic material can be dispersed in the hydrogen absorbing layer.

The hydrogen absorbing layer can be in contact with the cathode and further includes an adhesive material.

The light emitting display apparatus can further comprise an upper substrate opposite to the lower substrate, and the upper substrate and the lower substrate are attached using the hydrogen absorbing layer.

The hydrogen absorbing layer can further include at least one of a getter and a hydrogen compound.

The light emitting display apparatus can further comprise an upper substrate opposite to the lower substrate; and an adhesive layer being configured to attach the upper substrate and the lower substrate.

The light emitting display apparatus can further comprise an over coating layer on the thin film transistor; and a bank on the over coating layer, wherein the inorganic material is in the over coating layer and the bank.

The bank can be in contact with an upper portion of the first passivation layer and is formed so as to enclose a side surface of the anode and a side surface of the over coating layer.

The thin film transistor can include a semiconductor layer and the semiconductor layer is formed of an oxide semiconductor or an amorphous semiconductor.

The anode can include a transparent conductive layer or includes a reflective layer and a transparent conductive layer on the reflective layer.

The light emitting display apparatus can further comprise a second passivation layer between the light emitting diode and the hydrogen absorbing layer, the second passivation layer includes hydrogen.

The hydrogen absorbing layer can be in contact with an upper surface and a side surface of the second passivation layer.

A portion of a lower surface of the hydrogen absorbing layer can be in contact with the first passivation layer.

The light emitting display apparatus can further comprise a color filter overlapping the light emitting diode, and the color filter includes hydrogen.

The first passivation layer can be disposed to cover an upper surface and side surface of the thin film transistor to protect the thin film transistor from oxygen or moisture from an outside of the light emitting display apparatus.

The light emitting diode can be disposed between the hydrogen absorbing layer and the first passivation layer.

According to another aspect of the present disclosure, a light emitting display apparatus can include a lower substrate, a thin film transistor on the lower substrate, the thin film transistor including an oxide semiconductor layer, a passivation layer on the thin film transistor, a light emitting diode on the thin film transistor and the passivation layer, the light emitting diode including an anode, a light emitting layer on the anode, and a cathode on the light emitting layer, and a seal on the light emitting diode, the seal including a hydrogen absorbing filler.

The hydrogen absorbing filler can be dispersed in the seal.

The seal covers a side surface of the light emitting diode.

The light emitting display apparatus can further include a color filter on the passivation layer in an emission area of the light emitting diode.

The light emitting display apparatus can further comprise an over coating layer on the thin film transistor and the passivation layer, the seal and the passivation layer can surround the light emitting diode and the over coating layer.

The light emitting display apparatus can further comprise an over coating layer on the thin film transistor and the passivation layer, the seal is in contact with the passivation layer at outer portions of the light emitting diode and the over coating layer.

According to another aspect of the present disclosure, a light emitting display apparatus can include a lower substrate which includes a thin film transistor and a light emitting diode, an upper substrate on the lower substrate, an adhesive layer between the lower substrate and the upper substrate, and the adhesive layer being on the thin film transistor, and a seal between the adhesive layer and the upper substrate, the seal including a hydrogen absorbing filler in contact with the adhesive layer.

According to another aspect of the present disclosure, a method of manufacturing a light emitting display apparatus can include: forming a thin film transistor on a lower substrate, forming a passivation layer on the thin film transistor, forming a light emitting diode including an anode, a light emitting layer, and a cathode on the passivation layer, and forming a hydrogen absorbing layer having an inorganic material on the light emitting diode.

The forming of a hydrogen absorbing layer can include performing a chemical vapor deposition method, a sputtering method, or a thermal evaporation method on the inorganic material.

The forming of a hydrogen absorbing layer can include disposing an organic material on the light emitting diode, and dispersing or doping the inorganic material in the organic material.

After the forming of a first passivation layer, forming a color filter on the first passivation layer.

The method can further include after the forming of a light emitting diode, forming a second passivation layer to cover an outer surface of the light emitting diode.