Display apparatus and method of manufacturing the same

A display apparatus includes a first substrate; a first light-emitting device, a second light-emitting device, and a third light-emitting device disposed over the first substrate, each of the first to third light-emitting devices including a first light emission layer; a second substrate disposed over the first substrate with the first to third light-emitting devices therebetween, the second substrate including a first through hole, a second through hole, and a third through hole overlapping the first to third light-emitting devices; a reflective layer on an inner surface of each of the first to third through holes; a first color filter layer in the first through hole; a second color filter layer and a second quantum dot layer in the second through hole; and a third color filter layer and a third quantum dot layer in the third through hole.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean Patent Application No. 10-2020-0030758, filed on Mar. 12, 2020, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

Field

Exemplary implementations of the invention relate generally to a display apparatus and a method of manufacturing the same, and more specifically, to a display apparatus and a method of manufacturing the same for reducing the defect ratio of the display apparatus and the amount of consumed material during manufacturing.

Discussion of the Background

A display apparatus includes a plurality of pixels. The plurality of pixels may emit different colors of light for implementing a full-color display apparatus. To this end, at least some pixels of the display apparatus each have a color conversion unit. Accordingly, first color light generated from a light-emitting portion of some pixels is converted into second color light while passing through a corresponding color conversion unit, and then the second color light is emitted to the outside.

SUMMARY

Applicant discovered that an excessive amount of a material for forming a color conversion unit of a display apparatus may be used and a high defect ratio of the display apparatus is caused during the manufacturing processes forming the color conversion unit.

Display apparatuses with color filters and color conversion units constructed according to the principles and exemplary implementations of the invention and methods of fabricating the same according to the principles of the invention are capable of guaranteeing a low defect ratio and reducing the amount of a material consumed during manufacturing processes. For example, these benefits may be achieved by forming the color filter and color conversion units in through holes of a separate upper substrate, which is subsequently joined to a lower substrate containing the display panel and light emitting elements.

According to an aspect of the invention, a display apparatus includes: a first substrate; a first light-emitting device, a second light-emitting device, and a third light-emitting device disposed over the first substrate, each of the first to third light-emitting devices including a first light emission layer; a second substrate disposed over the first substrate with the first to third light-emitting devices therebetween, the second substrate including a first through hole, a second through hole, and a third through hole overlapping the first to third light-emitting devices; a reflective layer on an inner surface of each of the first to third through holes; a first color filter layer in the first through hole; a second color filter layer and a second quantum dot layer in the second through hole; and a third color filter layer and a third quantum dot layer in the third through hole.

The first to third light-emitting devices may include a first pixel electrode, a second pixel electrode, and a third pixel electrode; and an opposite electrode overlapping the first to third pixel electrodes, wherein the first light emission layer may be disposed over the first to third pixel electrodes and interposed between the first to third pixel electrodes and the opposite electrode.

The first light emission layer may be configured to emit light in a first wavelength band, the second quantum dot layer may be configured to convert the light in the first wavelength band into light in a second wavelength band, and the third quantum dot layer may be configured to convert the light in the first wavelength band into light in a third wavelength band.

The reflective layer may cover a portion of a first surface of the second substrate outside the first to third through holes, the first surface of the second substrate facing the first substrate.

The second quantum dot layer may be between the second color filter layer and the second light-emitting device, and the third quantum dot layer may be between the third color filter layer and the third light-emitting device.

The first substrate may be a lower substrate, the second substrate may be an upper substrate, and an upper surface of the first color filter layer, an upper surface of the second color filter layer, and an upper surface of the third color filter layer, may form a substantially continuous surface with an upper surface of the upper substrate, the upper surface of the upper substrate opposite to the lower substrate.

The display apparatus may include a first protective layer between the second color filter layer and the second quantum dot layer and between the third color filter layer and the third quantum dot layer.

The first protective layer may be integrally formed as a single body over an entire surface of the second substrate.

The display apparatus may include a light transmission layer in the first through hole interposed between the first color filter layer and the first light-emitting device.

The first protective layer may be between the first color filter layer and the light transmission layer.

The display apparatus may include a second protective layer between the second quantum dot layer and the second light-emitting device and between the third quantum dot layer and the third light-emitting device.

The second protective layer may be integrally formed as a single body over substantially an entire surface of the second substrate.

The second protective layer may be in contact with the first protective layer on a portion of a lower surface of the second substrate outside the first to third through holes, the lower surface facing the first substrate.

The inner surface of each of the first to third through holes may be inclined with respect to a first surface of the second substrate, the first surface facing the first substrate.

A first cross-sectional area of each of the first to third through holes taken along a first plane substantially parallel to a first surface of the second substrate may be smaller than a second cross-sectional area of each of the first to third through holes taken along a second plane substantially parallel to the first surface of the second substrate, the second plane being closer to the first substrate than the first plane, the first surface facing the first substrate.

The second substrate may include an opaque material.

The second substrate may include a black pigment.

The second substrate may be opaque.

According to another aspect of the invention, a method of manufacturing a display apparatus includes the steps: forming a layer of a first substrate on a carrier substrate; forming the first substrate by forming a first through hole, a second through hole, and a third through hole in the layer of the first substrate; forming a reflective layer on the first substrate; removing the reflective layer on the carrier substrate in the first to third through holes; forming a first color filter layer in the first through hole; forming a second color filter layer in the second through hole; forming a third color filter layer in the third through hole; forming a first quantum dot layer on the second color filter layer in the second through hole; and forming a second quantum dot layer on the third color filter layer in the third through hole.

The method may further include the steps of: forming a first light-emitting device, a second light-emitting device, and a third light-emitting device over a second substrate, the first to third light-emitting devices including a first light emission layer; and aligning and bonding the first substrate and the second substrate to each other with the first to third light-emitting devices therebetween, wherein the first to third through holes may overlap the first to third light-emitting devices.

DETAILED DESCRIPTION

FIG.1is a cross-sectional view of an exemplary embodiment of a display apparatus constructed according to the principles of the invention. As shown inFIG.1, the display apparatus includes first to third pixels PX1to PX3. However, the display apparatus may include more pixels. InFIG.1, the first to third pixels PX1to PX3are adjacent to one another, but one or more exemplary embodiments are not limited thereto. For example, other elements such as wirings may be among the first to third pixels PX1to PX3. Accordingly, the first and second pixels PX1and PX2, for example, may not be adjacent to each other. Also, inFIG.1, cross-sections of the first to third pixels PX1to PX3may not be taken along the same direction.

The display apparatus includes a lower substrate100. The lower substrate100may include glass, metal, a polymer resin, or the like. When the lower substrate100is flexible or bendable, the lower substrate100may include a polymer resin such as a polyethersulfone, polyacrylate, polyetherimide, polyethylene naphthalate, polyethylene terephthalate, polyphynylene sulfide, polyarylate, polyimide, polycarbonate, or cellulose acetate propionate. The lower substrate100may be variously modified, for example, the lower substrate100may have a multi-layered structure including at least two layers and a barrier layer between the at least two layers. Each of the at least two layers may include a polymer resin, and the barrier layer may include an inorganic material such as silicon oxide, silicon nitride, silicon oxynitride, or the like.

A first pixel electrode311, a second pixel electrode321, and a third pixel electrode331are disposed on the lower substrate100. For example, a plurality of display devices is disposed on the lower substrate100. In addition to the display devices, first to third thin film transistors210,220, and230electrically connected to the display devices may be on the lower substrate100. InFIG.1, the display devices are in the form of organic light-emitting devices disposed on the lower substrate100but any type of light-emitting devices suitable for use as display devices in a display panel may be employed in exemplary embodiments of the invention. The organic light-emitting devices are electrically connected to the first to third thin film transistors210,220, and230through the first to third pixel electrodes311,321, and331.

InFIG.1, the first thin film transistor210is in the first pixel PX1, the second thin film transistor220is in the second pixel PX2, and the third thin film transistor230is in the third pixel PX3. In addition, the first to third thin film transistors210to230are respectively connected to the pixel electrodes of the display devices in the corresponding pixels. Hereinafter, the first thin film transistor210and the display device connected to the first thin film transistor210will be described for convenience of description, and the description may be also applied to the second and third thin film transistors220and230and the display devices connected to the second and third thin film transistors220and230. That is, descriptions of a second semiconductor layer221, a second gate electrode223, a second source electrode225a, and a second drain electrode225bof the second thin film transistor220, and the second pixel electrode321are omitted to avoid redundancy. Likewise, descriptions of a third semiconductor layer231, a third gate electrode233, a third source electrode235a, and a third drain electrode235bof the third thin film transistor230, and the third pixel electrode331are omitted to avoid redundancy.

The first thin film transistor210may include a first semiconductor layer211, a first gate electrode213, a first source electrode215a, and a first drain electrode215b, wherein the first semiconductor layer211may include amorphous silicon, polycrystalline silicon, an organic semiconductor material, or an oxide semiconductor material. The first gate electrode213may have various layered structures including various conductive materials, which are formed of, e.g., a Mo layer and an Al layer. Alternatively, the first gate electrode213may include a TiNx layer, an Al layer, and/or a Ti layer. The first source electrode215aand the first drain electrode215bmay also have various layered structures including various conductive materials, which are formed of, e.g., a Ti layer, an Al layer, and/or a Cu layer.

In order to ensure an insulating property between the first semiconductor layer211and the first gate electrode213, a first gate insulating layer121including an inorganic material such as silicon oxide, silicon nitride, and/or silicon oxynitride may be between the first semiconductor layer211and the first gate electrode213. In addition, a first interlayer insulating layer131including an inorganic material such as silicon oxide, silicon nitride, and/or silicon oxynitride may be on the first gate electrode213. The first source electrode215aand the first drain electrode215bmay be on the first interlayer insulating layer131. The insulating layer including the inorganic material may be formed through a chemical vapor deposition (CVD) or an atomic layer deposition (ALD) method. This will be also applied to exemplary embodiments and modifications thereof that will be described later.

A buffer layer110may be disposed between the first thin film transistor210and the lower substrate100. The buffer layer110may include an inorganic material such as silicon oxide, silicon nitride, and/or silicon oxynitride. The buffer layer110may improve the smoothness of an upper surface of the lower substrate100, or may prevent or reduce infiltration of impurities into the first semiconductor layer211of the first thin film transistor210from the lower substrate100.

In addition, a planarization layer140may be on the first thin film transistor210. For example, when an organic light-emitting device is on the first thin film transistor210as shown inFIG.1, the planarization layer140may planarize an upper portion of a protective layer covering the first thin film transistor210. The planarization layer140may include, for example, an organic material such as acryl, benzocyclobutene (BCB), hexamethyldisilioxane (HMDSO), etc. InFIG.1, the planarization layer140has a single-layered structure, but may be variously modified. For example, the planarization layer140may have a multi-layered structure.

A display device may be disposed on the planarization layer140of the lower substrate100. The organic light-emitting device as shown inFIG.1may be used as the display device. In the first pixel PX1, the organic light-emitting device may include, for example, the first pixel electrode311, an opposite electrode305, and an intermediate layer303between the first pixel electrode311and the opposite electrode305. For example, the intermediate layer303includes an emission layer. The first pixel electrode311is electrically connected to the first thin film transistor210by contacting one of the first source electrode215aand the first drain electrode215bvia an opening formed in the planarization layer140, as shown inFIG.1. The second pixel PX2includes the second pixel electrode321, and the third pixel PX3includes the third pixel electrode331. Each of the first to third pixel electrodes311to331includes a light transmission conductive layer including a conductive oxide material such as ITO, In2O3, IZO, etc., and a reflective layer including metal such as Al, Ag, etc. For example, the first to third pixel electrodes311to331may each have a triple-layered structure including ITO/Ag/ITO.

The intermediate layer303including the emission layer may be integrally formed as a single body over the first to third pixel electrodes311to331, and the opposite electrode305on the intermediate layer303may be integrally formed as a single body over the first to third pixel electrodes311to331. The opposite electrode305may include a light transmission conductive layer including ITO, In2O3, IZO, etc., and may include a semi-transmissive layer including metal such as Al, Ag, etc. For example, the opposite electrode305may include a semi-transmissive layer including Mg, Ag, etc.

A pixel defining layer150may be on the planarization layer140. The pixel defining layer150includes an opening corresponding to each of the pixels, e.g., an opening exposing at least a central portion of each of the first to third pixel electrodes311to331, and thus, defines the pixels. Also, in the example ofFIG.1, the pixel defining layer150increases the distance between an edge of each of the first to third pixel electrodes311to331, and the opposite electrode305, in order to prevent generation of an arc at the edge of the first to third pixel electrodes311to331. The pixel defining layer150may include, for example, an organic material such as polyimide, hexamethyldisiloxane (HMDSO), etc.

The intermediate layer303may include a low-molecular weight organic material or a polymer material. When the intermediate layer303includes a low-molecular weight material, the intermediate layer303may include a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL) in a single or multiple-layered structure and may be obtained by a vacuum deposition method. When the intermediate layer303includes a polymer material, the intermediate layer303may include an HTL and an EML. Here, the HTL may include PEDOT, and the EML may include a poly-phenylenevinylene (PPV)-based or polyfluorene-based polymer material. The intermediate layer303may be arranged by a screen printing method, an inkjet printing method, a deposition method, a laser induced thermal imaging (LITI) method, etc. However, the intermediate layer303is not limited thereto, but may have various structures.

The intermediate layer303may include a layer integrally formed as a single body over the first to third pixel electrodes311to331as described above, but alternatively, the intermediate layer303may include a layer patterned to correspond to each of the first to third pixel electrodes311to331. In either case, the intermediate layer303may include a first light emission layer. The first light emission layer may be integrally formed as a single body over the first to third pixel electrodes311to331, but alternatively, may be patterned to correspond to each of the first to third pixel electrodes311to331. The first light emission layer may emit light in a first wavelength band, e.g., light in a wavelength band from about 450 nm to about 495 nm.

The opposite electrode305is on the intermediate layer303to correspond to the first to third pixel electrodes311to331. The opposite electrode305may be integrally formed as a single body over a plurality of organic light-emitting devices.

As the organic light-emitting device may be easily damaged due to external moisture or oxygen, an encapsulation layer may cover the organic light-emitting device to protect the organic light-emitting device. The encapsulation layer may include a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer.

An upper substrate400is disposed above the lower substrate100, and the opposite electrode305may be between the upper substrate400and the lower substrate100. The upper substrate400may include a polymer resin. The upper substrate400may include, for example, a polymer resin such as polyethersulfone, polyacrylate, polyetherimide, polyethylene naphthalate, polyethylene terephthalate, polyphenylene sulfide, polyarylate, polyimide, polycarbonate, cellulose acetate propionate, etc. The upper substrate400may be variously modified. For example, the upper substrate400may have a multi-layered structure including at least two layers and a barrier layer between the at least two layers. The at least two layers may include the polymer resin. The barrier layer may include an inorganic material such as silicon oxide, silicon nitride, silicon oxynitride, etc. between the two layers. The upper substrate400may be flexible or bendable.

The upper substrate400may include first to third through holes410,420, and430respectively corresponding to the first to third pixel electrodes311to331. That the first to third through holes410to430correspond to the first to third pixel electrodes311to331denotes that the first through hole410overlaps the first pixel electrode311, the second through hole420overlaps the second pixel electrode321, and the third through hole430overlaps the third pixel electrode331, respectively, when viewed from a direction perpendicular to the upper substrate400(Z-axis direction).

An inner surface in each of the first to third through holes410to430of the upper substrate400is inclined with respect to a lower surface400bof the upper substrate400. The cross-sectional area of each of the first to third through holes410to430is defined as a cross-sectional area taken along a virtual plane (XY plane) substantially parallel to the lower surface400bof the upper substrate400. The cross-sectional area of each of the first through hole410to the third through hole430decreases in a direction from the lower surface400bto an upper surface400aof the upper substrate400. For example, a first cross-sectional area of each of the first through hole410to the third through hole430taken along a first virtual plane substantially parallel to the lower surface400bof the upper substrate400is smaller than a second cross-sectional area of each of the first through hole410to the third through hole430taken along a second virtual plane substantially parallel to the lower surface400bof the upper substrate400when the second virtual plane is closer to the lower surface400bof the upper substrate400than the first virtual plane.

A reflective layer403is in each of the first to third through holes410to430. In detail, the reflective layer403is on the inner surface in each of the first to third through holes410to430. The reflective layer403may include metal having reflectivity such as Al, Ag, etc. The reflective layer403may not be only located in the first to third through holes410to430, but also may be on the lower surface400bof the upper substrate400, the lower surface400bfacing the lower substrate100, as shown inFIG.1. In detail, the reflective layer403may cover a portion of the lower surface400bof the upper substrate400outside the first to third through holes410to430.

A first color filter layer413is in the first through hole410. In addition, a second color filter layer423and a second quantum dot layer425are in the second through hole420, and a third color filter layer433and a third quantum dot layer435are in the third through hole430.

The first color filter layer413may only transmit the light of a wavelength within a range from about 450 nm to about 495 nm, the second color filter layer423may only transmit the light of a wavelength within a range from about 495 nm to about 570 nm, and the third color filter layer433may only transmit the light of a wavelength within a range from about 630 nm to about 780 nm. The first to third color filter layers413to433may reduce external light reflection in the display apparatus.

For example, when the external light is incident on the first color filter layer413, only the light of the predetermined wavelength as described above may pass through the first color filter layer413and the light of other wavelengths may be absorbed by the first color filter layer413. Therefore, in the external light incident into the display apparatus, only the light of the predetermined wavelength as described above may pass through the first color filter layer413, and some of the light passing through the first color filter layer413is reflected by the opposite electrode305or the first pixel electrode311under the first color filter layer413and emitted to the outside. Consequently, only some of the external light incident into the space where the first pixel PX1is positioned may be reflected to the outside, and thus, the external light reflection may be reduced. The above description may be also applied to the second color filter layer423and the third color filter layer433.

The second quantum dot layer425may convert light in the first wavelength band generated by the intermediate layer303on the second pixel electrode321into light in a second wavelength band. For example, when the intermediate layer303on the second pixel electrode321generates light of a wavelength within a range from about 450 nm to about 495 nm, the second quantum dot layer425may convert the light into the light of a wavelength within a range from about 495 nm to about 570 nm. Accordingly, the light of the wavelength within the range from about 495 nm to about 570 nm is emitted from the second pixel PX2to the outside via the upper substrate400.

The third quantum dot layer435may convert the light in the first wavelength band generated by the intermediate layer303on the third pixel electrode331into light in a third wavelength band. For example, when the light of a wavelength within the range from about 450 nm to about 495 nm is generated from the intermediate layer303of the third pixel electrode331, the third quantum dot layer435may convert the light into the light having a wavelength within the range from about 630 nm to about 780 nm. Accordingly, the light of the wavelength within the range from about 630 nm to about 780 nm is emitted from the third pixel PX3to the outside via the upper substrate400.

Each of the second quantum dot layer425and the third quantum dot layer435may have a structure, in which quantum dots are dispersed in a resin. The quantum dots may include a semiconductor material such as cadmium sulfide (CdS), cadmium telluride (CdTe), zinc sulfide (ZnS), indium phosphide (InP), etc. Each of the quantum dots may have a size of several nanometers, and the wavelength of the light after conversion may vary depending on the size of each of the quantum dots. The second quantum dot layer425and the third quantum dot layer435may include any type of resin capable of light transmittance. For example, a polymer resin such as acryl, benzocyclobutene (BCB), or hexamethyldisiloxane (HMDSO) may be used as a material for forming the second quantum dot layer425and the third quantum dot layer435.

The first pixel PX1emits the light of a first wavelength generated by the intermediate layer303to the outside without converting the wavelength. Therefore, the first pixel PX1does not include a quantum dot layer. As described above, because the quantum dot layer is not necessary in the first through hole410, a light transmission layer (i.e., a transparent layer)415including a light-transmitting resin is disposed in the first through hole410. The light transmission layer415may include acryl, benzocyclobutene (BCB), or hexamethyldisilioxane (HMDSO). Alternatively, the light transmission layer415may not be in the first through hole410unlike in the illustrated embodiment ofFIG.1.

In the illustrated display apparatus, the light in first wavelength band is emitted to the outside from the first pixel PX1, the light in the second wavelength band is emitted to the outside from the second pixel PX2, and the light in the third wavelength band is emitted to the outside from the third pixel PX3. Therefore, the display apparatus may display full-color images.

During the manufacturing processes, the first to third through holes410to430are provided on the upper substrate400, and then, the first to third color filter layers413to433are positioned in the first to third through holes410to430. Therefore, mixing of the materials used during the processes of forming the first to third color filter layers413to433may be effectively prevented. For example, when the first color filter layer413is formed and the second color filter layer423is formed, the material used to form the first color filter layer413and the material used to form the second color filter layer423may be mixed on the substrate in the display apparatus according to the related art. However, in the display apparatus according to the illustrated exemplary embodiment, the first to third color filter layers413to433are in the first to third through holes410to430, and thus, mixing of the materials for forming the first to third color filter layers413to433may be prevented effectively.

In the display apparatus according to the related art, forming of a barrier layer on the substrate before forming the first and second color filter layers may be taken into account. The material for forming the first color filter layer and the material for forming the second color filter layer may not be mixed due to the barrier layer. However, in this case, in order to form the barrier layer to a sufficient height, a first barrier layer is formed and a second barrier layer has to be formed on the first barrier layer. Thus, processes may be complicated. In the display apparatus according to the illustrated exemplary embodiment, the process of forming the barrier layer during the manufacturing processes is obviated, and thus, the manufacturing processes may be simplified and a defect ratio may be decreased.

According to the display apparatus of the illustrated exemplary embodiment, the second quantum dot layer425and the third quantum dot layer435are in the second and third through holes420and430as described above. Therefore, the above descriptions about the first to third color filter layers413to433during the manufacturing processes may be also applied to the second and third quantum dot layers425and435. That is, in the display apparatus according to the illustrated exemplary embodiment, mixing of the materials used to form the second quantum dot layer425and the third quantum dot layer435during the manufacturing processes may be effectively prevented.

As a reference, the second quantum dot layer425is between the second color filter layer423and the opposite electrode305. Because the second color filter layer423transmits the light in the second wavelength band, the light in the first wavelength band generated by the intermediate layer303needs to be converted into the light in the second wavelength band by the second quantum dot layer425before being incident into the second color filter layer423that transmits the light in the second wavelength band. Likewise, the third quantum dot layer435is between the third color filter layer433and the opposite electrode305. Accordingly, an upper surface413aof the first color filter layer413, which is opposite to the direction towards the lower substrate100(e.g., the negative Z axis direction), an upper surface423aof the second color filter layer423in an opposite direction to the lower substrate100(e.g., the negative Z axis direction), and an upper surface433aof the third color filter layer433in an opposite direction to the lower substrate100(e.g., the negative Z axis direction) may form continuous surfaces with the upper surface400aof the upper substrate400, which is opposite to the direction towards the lower substrate100(e.g., the negative Z axis direction). For example, the upper surface413aof the first color filter layer413, the upper surface423aof the second color filter layer423, the upper surface433aof the third color filter layer433, and the upper surface400aof the upper substrate400may be substantially coplanar.

In addition, during the manufacturing processes or using the display apparatus after being manufactured, it may be necessary to prevent damage to the second and third quantum dot layers425and435. For example, an outgas generated from the second color filter layer423may damage the quantum dots in the second quantum dot layer425so that the quantum dots may not convert the light in the first wavelength band into the light in the second wavelength band. Likewise, an outgas generated from the third color filter layer433damages the quantum dots in the third quantum dot layer435so that the quantum dots may not convert the light in the first wavelength band into the light in the third wavelength band. Thus, it may be necessary to prevent the damages of the second and third quantum dot layers425and435from the outgas. To this end, a first protective layer405may be disposed between the second color filter layer423and the second quantum dot layer425, and between the third color filter layer433and the third quantum dot layer435. The first protective layer405may include an inorganic material such as silicon oxide, silicon nitride, or silicon oxynitride, such that the outgas may not pass through the first protective layer405. The first protective layer405may be integrally formed as a single body over the entire surface of the upper substrate400. Accordingly, the first protective layer405is between the first color filter layer413and the light transmission layer415in the first through hole410of the upper substrate400.

The first protective layer405includes an inorganic material, and thus may have a shape corresponding to a lower portion thereof when being formed. Accordingly, as shown inFIG.1, the first protective layer405is flat on a portion of the reflective layer403outside the first to third through holes410to430of the upper substrate400, and is formed along the reflective layer403in the first to third through holes410to430to be in contact with the first to third color filter layers413to433. Processes of forming the first protective layer405will be described later.

In addition, the intermediate layer303included in the organic light-emitting device is vulnerable to impurities such as external moisture or oxygen. Therefore, during the manufacturing or using the display apparatus after finishing the manufacturing, it is necessary to prevent outgas generated by the second and third quantum dot layers425and435from proceeding in a direction towards the intermediate layer303. To this end, a second protective layer407may be between the second quantum dot layer425and the opposite electrode305and between the third quantum dot layer435and the opposite electrode305. The second protective layer407may include an inorganic material such as silicon oxide, silicon nitride, or silicon oxynitride, such that the outgas may not pass through the second protective layer407. The second protective layer407may be integrally formed as a single body over the entire surface of the upper substrate400. Accordingly, the second protective layer407is in contact with the light transmission layer415in the first through hole410of the upper substrate400, is in contact with the second quantum dot layer425in the second through hole420, and is in contact with the third quantum dot layer435in the third through hole430. In addition, the second protective layer407is in contact with the first protective layer405on the portions in the lower surface400bof the upper substrate400, the portions are outside the first through third through holes410to430.

FIGS.2A to9are cross-sectional views or plan views illustrating processes of manufacturing the display apparatus ofFIG.1. In detail,FIGS.2A to9are cross-sectional views or plan views illustrating exemplary processes of manufacturing the upper substrate400, the first to third color filter layers413to433, the second quantum dot layer425, the third quantum dot layer435, the first protective layer405, and the second protective layer407in the display apparatus ofFIG.1.

As shown inFIGS.2B and3, the upper substrate400including the first to third through holes410to430is prepared. Here,FIG.2Bshows a cross-section of the display apparatus taken along line II-II ofFIG.3which is a plan view.

Referring toFIG.2A, a layer400_0for forming the upper substrate400is prepared on a carrier substrate10. Further, referring toFIG.2B, the first to third through holes410to430are formed in the layer400_0. For example, a material for forming polyimide is applied onto the carrier substrate10by a slit coating method, etc. to obtain the layer400_0, and processes of exposing and developing certain portions by using a photomask are performed to form the first to third through holes410to430in the layer400_0on the carrier substrate10. After that, the material for forming polyimide is cured through a UV exposure, a thermal treatment, etc. to obtain the upper substrate400including the first to third through holes410to430as shown inFIGS.2B and3. The carrier substrate10may include, for example, a glass substrate.

The upper substrate400may be variously modified. For example, the upper substrate400may include other polymer resins than the polyimide, and may have a multi-layered structure including at least two layers and a barrier layer between the at least two layers. The at least two layers may include a polymer resin. The barrier layer may include an inorganic material such as silicon oxide, silicon nitride, silicon oxynitride, etc.

When the material for forming the upper substrate400such as polyimide has the same properties as those of a photoresist, the material is applied onto the carrier substrate10to form the layer400_0as described above, and after that, the processes of exposing and developing certain portions by using a photomask are performed to form the first to third through holes410to430in the layer400_0on the carrier substrate10. However, when the material for forming the upper substrate400does not have the same properties as those of the photoresist, a layer400_0is formed by using the material for forming the upper substrate400on the carrier substrate10, and after that, the first to third through holes410to430may be formed in the layer400_0by a wet etching method using the photoresist.

As the first to third through holes410and430are obtained through the processes such as the exposure, the development, etc., in any of the cases in which the material for forming the upper substrate400has characteristics of the photoresist and in which additional photoresist is used, an inner surface of each of the first to third through holes410to430is inclined with respect to the lower surface400bof the upper substrate400. Accordingly, the reflective layer403, which is to be formed later, may be arranged on the inner surface of each of the first to third through holes410to430without causing a defect. Here, a cross-sectional area of each of the first to third through holes410to430taken along a virtual plane (XY plane) that is in substantially parallel with the lower surface400bof the upper substrate400is reduced as approached from the lower surface400btowards an upper surface400aof the upper substrate400.

The upper substrate400may be formed by another method. For example, a layer400_0is formed on the carrier substrate10by using a material for forming the upper substrate400. After that, a laser beam is radiated to a certain portion in the layer400_0to obtain the upper substrate400including the first to third through holes410to430.

When the laser beam is radiated, the laser beam is not radiated to the layer400_0on the carrier substrate10by passing through the carrier substrate10, but is directly radiated onto the layer400_0on the carrier substrate10. With reference to a coordinate axis shown inFIG.2B, the layer400_0for forming the upper substrate400is arranged on a surface of the carrier substrate10, the surface is in the negative Z axis direction, and a laser beam is radiated in the positive Z axis direction from a laser beam source located in the negative Z axis direction with respect to the layer400_0, and then, the laser beam may be directly radiated to the layer400_0on the carrier substrate10. As such, as shown inFIGS.2B and3, an area of a cross-section in each of the first to third through holes410to430, wherein the cross-section is taken along a virtual plane (XY plane) that is in substantially parallel with the lower surface400bof the upper substrate400, may be gradually reduced as approached from the lower surface400btowards the upper surface400aof the upper substrate400.

In addition, as shown inFIG.4, the reflective layer403is formed on the inner surface in each of the first to third through holes410to430in the upper substrate400. For example, a metal layer is entirely formed on the lower surface400bof the upper substrate400by a sputtering method, etc. Here, the metal layer is also on the carrier substrate10in each of the first to third through holes410to430. After that, the metal layer on the carrier substrate10in each of the first to third through holes410to430is removed to obtain the reflective layer403as shown inFIG.4.

Removing of the metal layer on the carrier substrate10in each of the first to third through holes410to430may be performed by using a dry etching method using the photoresist. For example, the photoresist is arranged on the metal layer that is entirely on the lower surface400bof the upper substrate400, and then, exposure and developing processes are performed to remove only the photoresist on the metal layer on the carrier substrate10in each of the first to third through holes410to430. After that, the metal layer on the carrier substrate10in each of the first to third through holes410and430may be removed by the dry etching method. Here, the photoresist remaining on the reflective layer403is also removed.

As described above, because the inner surface in each of the first to third through holes410to430is inclined with respect to the lower surface400bof the upper substrate400, the reflective layer403may be formed on the inner surface in each of the first to third through holes410to430of the upper substrate400.

When the inner surface in each of the first to third through holes410to430is substantially perpendicular to the lower surface400bof the upper substrate400, a defect of not forming the metal layer on the inner surface in each of the first to third through holes410to430may occur when the metal layer is entirely formed on the lower surface400bof the upper substrate400.

After that, as shown inFIG.5, the first color filter layer413in the first through hole410, the second color filter layer423in the second through hole420, and the third color filter layer433in the third through hole430are formed by an inkjet printing method. As the color filter layers are formed by the inkjet printing method, the amount of waste material generated when forming the color filter layers may be reduced. Moreover, as the first to third color filter layers413to433are respectively in the first to third through holes410to430, mixing of the materials that are used during the processes of forming the first to third color filter layers413to433may be effectively prevented.

In addition, the first protective layer405is formed by using the silicon oxide, silicon nitride, or silicon oxynitride, so as to correspond to the entire lower surface400bof the upper substrate400, as shown inFIG.6. Accordingly, the first protective layer405may be in contact with the reflective layer403on the inner surfaces of the first to third through holes410to430, as well as the first to third color filter layers413to433. Because the reflective layer403is also on the outer portions of the first to third through holes410to430in the lower surface400bof the upper substrate400, the first protective layer405is also in contact with the reflective layer403on the corresponding portions. The first protective layer405may be formed by a CVD method. Here, in order not to damage the first to third color filter layers413to433that are formed previously, a low temperature CVD method performed at the temperature of about 200° C. or less may be used.

After forming the first protective layer405, as shown inFIG.7, the second quantum dot layer425and the third quantum dot layer435are formed in the second and third through holes420and430. As the quantum dot layers are formed by the inkjet printing method, the amount of waste material generated when forming the quantum dot layers may be reduced. In addition, because the second and third quantum dot layers425and435are in the second and third through holes420and430, mixing of the materials that are used in the processes of forming the second and third quantum dot layers425and435may be effectively prevented. The light transmission layer415may be formed on the first protective layer405in the first through hole410, alternatively.

In addition, the second protective layer407is formed by using the silicon oxide, silicon nitride, or silicon oxynitride, so as to correspond to the entire lower surface400bof the upper substrate400, as shown inFIG.8. Accordingly, the second protective layer407may be in contact with the first protective layer405on the outside of the first to third through holes410to430, as well as the second and third quantum dot layers425and435. The second protective layer407may be formed by the CVD method. Here, in order not to damage the first to third color filter layers413to433and/or the second and third quantum dot layers425and435that are formed previously, the low temperature CVD method executed at a temperature of about 200° C. or less may be used.

As described above, after forming the upper substrate400, the first to third color filter layers413to433, the second quantum dot layer425, the third quantum dot layer435, the first protective layer405, and the second protective layer407, the upper substrate400and the lower substrate100are bonded to each other as shown inFIG.9. Before the above process, the first to third thin film transistors210to230, the first to third pixel electrodes311to331, the intermediate layer303, and the opposite electrode305are formed on the lower substrate100through separate processes. In addition, after bonding the upper substrate400to the lower substrate100, the carrier substrate10is removed from the upper substrate400, and then, the display apparatus shown inFIG.1is manufactured. Alternatively, the carrier substrate10may be removed before bonding the upper substrate400and the lower substrate100to each other, and then, the upper substrate400and the lower substrate100are bonded to each other.

Bonding of the lower substrate100and the upper substrate400may be effected by a sealant applied to an outer portion of a display area to allow the lower substrate100and the upper substrate400to be bonded to each other. Alternatively, a filling material is located in a space between the lower substrate100and the upper substrate400as shown inFIGS.1and9, and then, the lower substrate100and the upper substrate400are bonded to each other via the filling material. In this case, the filling material is a light-transmitting filling material including a light-transmissive polymer resin such as polyimide, epoxy, etc.

In the above description, the reflective layer403is on the outer portions of the first to third through holes410to430on the lower surface400bof the upper substrate400, as well as on the inner surface in each of the first to third through holes410to430in the upper substrate400. However, one or more exemplary embodiments are not limited thereto. For example, as shown inFIG.10, which is a cross-sectional view of another exemplary embodiment of the display apparatus ofFIG.1, the reflective layer403may be only on the inner surface in each of the first to third through holes410to430in the upper substrate400, and may not on the outer portions of the first to third through holes410to430on the lower surface400bof the upper substrate400. In this case, the first protective layer405is in contact with the lower surface400bof the upper substrate400on the outer portions of the first to third through holes410to430.

In addition, a surface of the second color filter layer423in the second through hole420, the surface facing the second quantum dot layer425, and a surface of the third color filter layer433in the third through hole430, the surface facing the third quantum dot layer435, may be substantially flat to be substantially parallel with the upper surface400aof the upper substrate400. This is because the second color filter layer423and the third color filter layer433are formed by the inkjet printing method, and thus the material for forming the second color filter layer423and the third color filter layer433is in a liquid state. The liquid is cured and/or baked during the manufacturing processes, the second and third color filter layers423and433are in solid state. Likewise, a surface of the first color filter layer413, the surface facing the opposite electrode305, is substantially flat to be substantially parallel with the upper surface400aof the upper substrate400.

The display apparatus having the organic light-emitting devices as display devices has been described, but the exemplary embodiments are not limited thereto. For example, in the structure shown inFIG.1, the display devices connected to the first to third thin film transistors210,220, and230may not include the organic light-emitting devices, but other light emitting devices. For example, instead of the first to third pixel electrodes311,321, and331, the intermediate layer303, and the opposite electrode305, a first light-emitting device may be connected to the first thin film transistor210, a second light-emitting device may be connected to the second thin film transistor220, and a third light-emitting device may be connected to the third thin film transistor230. Each of the first to third light-emitting devices may include a first light emission layer. The first light emission layer may emit light in the first wavelength band, e.g., light of a wavelength within the range from about 450 nm to about 495 nm.

In the display apparatus according to the above-described exemplary embodiment the first to third light-emitting devices in the display apparatus include the first to third pixel electrodes311to331, the opposite electrode305corresponding to the first to third pixel electrodes311to331, and the first light emission layers in the first to third light-emitting devices are disposed on the first to third pixel electrodes311to331to be between the first to third pixel electrodes311to331and the opposite electrode305. According to another exemplary embodiment, the first to third light-emitting devices may include a nano-LED. The nano-LED is a kind of LED and may have a size of several nanometers to tens of nanometers. A pixel of the display apparatus may include one nano-LED or a plurality of nano-LEDs having smaller sizes.

In addition, in the display apparatus according to the above exemplary embodiments and modified examples thereof, the upper substrate400may include an opaque material, i.e., the upper substrate400may be opaque. For example, the upper substrate400may include a black pigment such as carbon black or an opaque material. This may be implemented when the material for forming the upper substrate400applied onto the carrier substrate10includes the black pigment or the opaque material. Alternatively, when the material for forming the upper substrate400is applied to form a layer, the layer may include particles including black or opaque material. In this case, the upper substrate400may function as a black matrix, and thus, various effects such as preventing the visibility of displayed images from degrading due to the external light may be obtained.

According to principles and one or more exemplary embodiments of the invention, the display apparatus may have a low defect ratio during the manufacturing processes and consume less amount of material. However, the exemplary embodiments are not limited to the above effects.