Display device

A display device is disclosed. In one aspect, the display device includes a substrate, a display unit formed over the substrate and a thin film encapsulation layer covering the display unit. The display device further includes an encapsulation substrate formed over the thin film encapsulation layer and encapsulating the display unit and a photosensor formed on an end of the thin film encapsulation layer.

RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2014-0184962, filed on Dec. 19, 2014, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

Field

The described technology generally relates to a display device.

Description of the Related Technology

Along with the development of information technology, the market for display devices, which are media for connecting users with information, has expanded. Accordingly, display devices, such as liquid crystal displays (LCDs), organic light-emitting diode (OLED) displays, electrophoretic displays (EPDs), and plasma display panels (PDPs), are widely used.

Among the above-described display devices, LCDs, OLED displays, and EPDs are being developed into flexible display devices, and some of them have been implemented as cubic image display devices.

With the rapid development of semiconductor technology, display panels using OLEDs from among various display panels which are used in display devices have attracted much attention of late.

In OLED displays, pixels, each of which is a basic unit of image expression, are arranged on a substrate in a matrix form, and a thin film transistor (TFT) is included in each pixel to independently control the pixel.

Such OLED displays may be classified into top-emission type display devices and bottom-emission type display devices according to the direction in which light is emitted.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

One inventive aspect relates to a display device.

Another aspect is a display device that includes a substrate; a display unit formed on the substrate; a thin film encapsulation formed on an upper surface of the substrate to cover the display unit; an encapsulation substrate formed on an upper surface of the thin film encapsulation to encapsulate the display unit; and a photosensor on one end of the thin film encapsulation.

The thin film encapsulation may include a plurality of organic layers and a plurality of inorganic layers which are alternately stacked.

The plurality of organic layers and the plurality of inorganic layers may have different refractive indices from each other.

A total reflection of light may repeatedly occur within the thin film encapsulation and the reflected light travels sideways.

The display device may further include an adhesion layer between the thin film encapsulation and the encapsulation substrate, the adhesion layer attaching the thin film encapsulation to the encapsulation substrate.

The adhesion layer may include a transparent organic material.

The adhesion layer may include metal particles.

A reflection layer may be formed on an upper surface of the adhesion layer.

Another aspect is a display device that includes a substrate having a light-emitting region and an outer region; an encapsulation substrate formed opposite the substrate; a display unit formed in the light-emitting region of the substrate; a thin film encapsulation formed on an upper surface of the substrate to cover the display unit; and a photosensor in the outer region of the substrate.

The thin film encapsulation may include a plurality of organic layers and a plurality of inorganic layers which are alternately stacked.

The plurality of organic layers and the plurality of inorganic layers may have different refractive indices from each other.

A total reflection of light may repeatedly occur within the thin film encapsulation and the reflected light travels sideways.

The photosensor may be formed on a lateral surface of the thin film encapsulation.

The display device may further include an adhesion layer between the thin film encapsulation and the encapsulation substrate, the adhesion layer attaching the thin film encapsulation to the encapsulation substrate.

The adhesion layer may include a transparent organic material.

The adhesion layer may include metal particles.

A reflection layer may be formed on an upper surface of the adhesion layer.

Another aspect is a display device comprising: a substrate; a display unit formed over the substrate; a thin film encapsulation layer covering the display unit; an encapsulation substrate formed over the thin film encapsulation layer and encapsulating the display unit; and a photosensor formed on an end of the thin film encapsulation layer.

In the above display device, the thin film encapsulation layer comprises a plurality of organic layers and a plurality of inorganic layers which are alternately stacked. In the above display device, the organic layers and the inorganic layers have different refractive indices from each other. In the above display device, when a total reflection of light repeatedly occurs within the thin film encapsulation layer, the reflected light is configured to travel sideways. The above display device further comprises an adhesion layer formed between the thin film encapsulation layer and the encapsulation substrate, wherein the adhesion layer attaches the thin film encapsulation layer to the encapsulation substrate. In the above display device, the adhesion layer is formed of a transparent organic material.

In the above display device, the adhesion layer comprises a plurality of metal particles. The above display device further comprises a reflection layer formed over an upper surface of the adhesion layer. The above display device, the thickness of the photosensor is substantially the same as the combined thickness of the thin film encapsulation layer, the adhesion layer and the encapsulation substrate. In the above display device, the photosensor contacts lateral surfaces of the thin film encapsulation layer, the adhesion layer and the encapsulation substrate.

Another aspect is a display device comprising: a substrate including a light-emitting region and an outer region; an encapsulation substrate formed opposite the substrate; a display unit formed in the light-emitting region of the substrate; a thin film encapsulation layer covering the display unit; and a photosensor formed in the outer region of the substrate.

In the above display device, the thin film encapsulation layer comprises a plurality of organic layers and a plurality of inorganic layers which are alternately stacked. In the above display device, the organic layers and the inorganic layers have different refractive indices from each other. In the above display device, the photosensor is formed on a lateral surface of the thin film encapsulation layer. The above display device further comprises an adhesion layer formed between the thin film encapsulation layer and the encapsulation substrate, wherein the adhesion layer attaches the thin film encapsulation layer to the encapsulation substrate. In the above display device, the thickness of the photosensor is substantially the same as the combined thickness of the thin film encapsulation layer, the adhesion layer and the encapsulation substrate. In the above display device, the photosensor contacts lateral surfaces of the thin film encapsulation layer, the adhesion layer and the encapsulation substrate.

Another aspect is a display device comprising: a substrate; a display unit formed over the substrate and configured to output light; a thin film encapsulation layer covering the display unit; and a photosensor contacting a lateral surface of the thin film encapsulation layer and configured to sense at least part of the light output from the display unit.

The above display device further comprises an encapsulation substrate formed over the thin film encapsulation layer and encapsulating the display unit, wherein the photosensor contacts a lateral surface of the encapsulation substrate. In the above display device, the thickness of the photosensor is greater than the combined thickness of the thin film encapsulation layer and the encapsulation substrate.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

As the described technology allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. Hereinafter, effects and features of the described technology and a method for accomplishing them will be described more fully with reference to the accompanying drawings, in which exemplary embodiments are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein.

It will be understood that although the terms “the first”, “the second”, etc. may be used herein to describe various components, these components should not be limited by these terms. These components are only used to distinguish one component from another.

As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. In this disclosure, the term “substantially” includes the meanings of completely, almost completely or to any significant degree under some applications and in accordance with those skilled in the art. The term “connected” can include an electrical connection.

FIG. 1is a cross-sectional view of a display unit20according to an embodiment, andFIG. 2is a cross-sectional view of a display device including the display unit ofFIG. 1according to an embodiment.

As illustrated inFIG. 2, the display device according to the present embodiment includes a substrate10, the display unit20, a thin film encapsulation layer30, an encapsulation substrate50, and a photosensor60.

The substrate10can be formed of a transparent glass material containing SiO2as a main component. However, the material used to form the substrate10is not limited thereto, and the substrate10can be formed of a transparent plastic material.

In the display unit20formed on the substrate10, an array of pixels may be formed. Each of the pixels may include a thin film transistor and a light-emitting device that is controlled by the thin film transistor. The light-emitting device may be an organic light-emitting device, which is a self-emission type device.

Only a case where the display unit20includes organic light-emitting devices will now be described for convenience of explanation.

The display unit20will now be described in more detail with reference toFIG. 1.

As illustrated inFIG. 1, in the display device according to the present embodiment, a buffer layer21is formed on the substrate10. A buffer layer21may serve as a barrier layer and/or a blocking layer for preventing diffusion of impurity ions and penetration of moisture or external air and planarizing an upper surface of the substrate10.

A semiconductor layer A of a thin film transistor TFT is formed on the buffer layer21. The semiconductor layer A may be formed of polysilicon and may include a channel region undoped with impurities and a source region and a drain region which are doped with impurities and are respectively formed both sides of the channel region. The impurities may vary depending on the type of thin film transistor, and may be N-type impurities or P-type impurities.

The semiconductor layer A may be formed of a semiconductor including amorphous silicon or crystal silicon, and may be deposited using any of various deposition methods. The crystal silicon may be formed by crystallizing amorphous silicon. Amorphous silicon may be crystallized using any of various methods, such as rapid thermal annealing (RTA), solid phase crystallization (SPC), excimer laser annealing (ELA), metal induced crystallization (MIC), metal induced lateral crystallization (MILC), and sequential lateral solidification (SLS). The semiconductor layer A may be patterned by photolithography.

A gate insulating layer23is deposited on the entire surface of the substrate10such that its covers the semiconductor layer A. The gate insulating layer23may be formed of an inorganic material, such as silicon oxide or silicon nitride, and have a multilayer structure or single-layer structure. In some embodiments, the gate insulating layer23may be formed of silicon nitride (SiNx), silicon oxide (SiO2), hafnium (Hf) oxide, or aluminum oxide. The gate insulating layer23may be formed using any of various deposition methods, such as Chemical Vapour Deposition (CVD) and Plasma Enhanced Chemical Vapour Deposition (PECVD). The gate insulating layer23insulates the semiconductor layer A from a gate electrode G.

The gate electrode G may be formed of at least one metal selected from the group consisting of molybdenum (Mo), aluminum (Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chrome (Cr), calcium (Ca), titanium (Ti), tungsten (W), and copper (Cu).

An interlayer insulating layer25is deposited on the entire surface of the substrate10such that its covers the gate electrode G.

The interlayer insulating layer25may be formed of an inorganic material or an organic material. In some embodiments, the interlayer insulating layer25may be formed of an inorganic material. For example, the interlayer insulating layer25may be formed of metal oxide or metal nitride. In detail, the inorganic material may include silicon oxide (SiO2), silicon nitride (SiNx), silicon oxynitride (SiON), aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), zirconium oxide (ZrO2), or the like. The interlayer insulating layer25may be formed of an inorganic material, such as silicon oxide (SiOx) and/or silicon nitride (SiNx), in a multi-layered or single-layered structure. In some embodiments, the interlayer insulating layer25may have a double-layer structure of SiOx/SiNy or SiNx/SiOy. The interlayer insulating layer25may be formed using any of various deposition methods, such as CVD and PECVD.

The interlayer insulating layer25may insulate the gate electrode G from wirings formed on an upper surface of the interlayer insulating layer25.

A source electrode S and a drain electrode D of the thin film transistor TFT are formed on the interlayer insulating layer25.

A planarization layer27can be formed on substantially the entire surface of the substrate10such that its covers the source electrode S and the drain electrode D. A pixel electrode281may be formed on the planarization layer27. The pixel electrode281is connected to the drain electrode D of the thin film transistor TFT through a via hole.

The planarization layer27can be formed of an insulating material. For example, the planarization layer27can be formed of an inorganic material, an organic material, or an organic/inorganic compound in a single-layer or multilayer structure, and may be formed using any of various deposition methods. In some embodiments, the planarization layer27may be formed of at least one selected from the group consisting of polyacrylates resin, epoxy resin, phenolic resin, polyamides resin, polyimides resin, unsaturated polyesters resin, poly phenylenethers resin, poly phenylenesulfides resin, and benzocyclobutene (BCB).

An organic light-emitting diode (OLED) may be formed on the thin film transistor TFT. The OLED includes the pixel electrode281, an intermediate layer283including an organic emission layer, and an opposite electrode285. The display device according to the present embodiment may further include a pixel defining layer29and a spacer (not shown).

The pixel electrode281may be electrically connected to the drain electrode D of the thin film transistor TFT by filling the via hole of the planarization layer27. The pixel electrode281and/or the opposite electrode285may be transparent electrodes or reflective electrodes. When the pixel electrode281and/or the opposite electrode285are transparent electrodes, the pixel electrode281and/or the opposite electrode285may be formed of a material selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and indium oxide (In2O3). When the pixel electrode281and/or the opposite electrode285are reflective electrodes, the pixel electrode281and/or the opposite electrode285may include a reflective layer that is formed of a material selected from the group consisting of silver (Ag), magnesium (Mg), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), and a combination thereof, and a transparent layer that is formed of a material selected from the group consisting of ITO, IZO, ZnO, and In2O3. In some embodiments, the pixel electrode281or the opposite electrode285may have an ITO/Ag/ITO structure.

The pixel defining layer29may define a pixel region and a non-pixel region. The pixel defining layer29includes an aperture via which the pixel electrode281is exposed, and may be formed to cover the entire surface of the substrate10. The intermediate layer283, which will be described later, may be formed in the aperture, and thus the aperture may serve as a substantial pixel region.

The pixel electrode281, the intermediate layer283, and the opposite electrode285constitute the OLED. Holes and electrons injected into the pixel electrode281and the opposite electrode285of the OLED may combine with each other in the organic emission layer of the intermediate layer283to thereby generate light.

The intermediate layer283may include an organic emission layer. As another example, the intermediate layer283includes an organic emission layer. However, the intermediate layer283may further include at least one selected from a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), and an electron injection layer (EIL). The present embodiment is not limited thereto, and the intermediate layer283may further include the other functional layers in addition to an organic emission layer.

The HIL may be formed of a phthalocyanine compound such as copper phthalocyanine, or TCTA, m-MTDATA, or m-MTDAPB which is a star-bust type amine

The HTL may be formed of N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1 -biphenyl]-4,4′-diamine (TPD), N,N′-di(naphthalene-1-yl)-N,N′-diphenyl benzidine (α-NPD), and the like.

The EIL may be formed of a material such as LiF, NaCl, CsF, Li2O, BaO, or Liq.

The ETL may be formed of Alg3.

Examples of the dopant material of the organic emission layer may include 4,4′-bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi), 9,10-di(naph-2-tyl)anthracene (ADN), 3-tert-butyl-9,10-di(naph-2-tyl)anthracene (TBADN), and the like.

The opposite electrode285is formed on the intermediate layer283. The opposite electrode285forms an electric field together with the pixel electrode281so that light is emitted by the intermediate layer283. The pixel electrode281may be patterned in each pixel, and the opposite electrode285may be formed so that a common voltage is applied to all of the pixels.

The pixel electrode281and the opposite electrode285may be formed as transparent electrodes or as reflective electrodes. The pixel electrode281may function as an anode and the opposite electrode285may function as a cathode, but the present invention is not limited thereto. For example, the pixel electrode281may function as a cathode, and the opposite electrode285may function as an anode.

Although only one OLED is illustrated inFIG. 2, a display panel may include a plurality of OLEDs. One pixel may be formed in each OLED. Each of the pixels may emit light of a red color, a green color, a blue color, or a white color.

However, the present invention is not limited thereto. The intermediate layer283may be commonly formed on the entire surface of the pixel electrode281regardless of locations of the pixels. In this case, the organic emission layer may be formed by stacking a light-emitting substance emitting a red light, a light-emitting substance emitting a green light, and a light-emitting substance emitting a blue light on one another or by mixing a light-emitting substance emitting a red light, a light-emitting substance emitting a green light, and a light-emitting substance emitting a blue light. Any combination of other various colors, which is capable of emitting a white light, may be employed in addition to a combination of red, green, and blue colors. The display device may further include a color converting layer or a color filter that coverts the white light into a light of a predetermined color.

A protection layer (not shown) may be formed on the opposite electrode285and may cover and protect the OLED. An inorganic insulation layer and/or an organic insulation layer may be used as the protection layer.

The spacer (not shown) may be formed between pixel regions in a display region, The spacer may maintain an interval between the substrate10and the encapsulation substrate50and prevent degradation of the display characteristics by external impacts.

The spacer may be formed on the pixel defining layer29. The spacer may protrude from the pixel defining layer29toward the encapsulation substrate50.

In some embodiments, the spacer may include the same material as the pixel defining layer29and may be formed by using the same process as the process for forming the pixel defining layer29. In other words, the pixel defining layer29and the spacer may be substantially simultaneously or concurrently formed by adjusting the amount of exposure by using a halftone mask during an exposure process. However, the present invention is not limited thereto. The pixel defining layer29and the spacer may be sequentially or independently formed, and may be independent structures formed of different materials.

As illustrated inFIG. 2, the display device according to the present embodiment may be divided into a light-emitting region A, in which the display unit20emits light, and an outer region B, which is a remaining region of the display device.

The light-emitting region A may include the above-described display unit20as illustrated inFIG. 2. The thin film encapsulation or thin film encapsulation layer30may be formed on the substrate10such that it covers the display unit20.

FIG. 3is a cross-sectional view illustrating the thin film encapsulation layer30in more detail, according to an embodiment.

As illustrated inFIG. 3, the thin film encapsulation30may be formed on the substrate10such that it covers the display unit20. The thin film encapsulation30may have a structure in which a plurality of thin film layers are stacked. Thus, the thin film encapsulation30may have a structure in which an organic layer31and an inorganic layer33are alternately stacked.

Although a first organic layer31a, a first inorganic layer33a, a second organic layer31b, and a second inorganic layer33bare sequentially stacked on the display unit20inFIG. 3, the number of thin film layers that are stacked is not limited thereto.

The inorganic layer33may firmly block the penetration of oxygen or moisture, and the organic layer31may absorb stress generated by the inorganic layer33so that the thin film encapsulation may be flexible.

The inorganic layer33may be a single layer or a layer stack including metal oxide or metal nitride. For example, the first and second inorganic layers33aand33bmay include SiNx, Al2O3, SiO2, or TiO2.

The organic layer31may include a polymer and may be a single layer or a layer stack including polyethylene terephthalate, polyimide, polycarbonate, epoxy, polyethylene, or polyacrylate. For example, the first and second organic layers31aand31bmay be formed of polyacrylate. In detail, the first and second organic layers31aand31bmay include a result of polymerizing a monomer composition including diacrylate-based monomer and triacrylate-based monomer. The monomer composition may further include monoacrylate-based monomer. The monomer composition may further include a well-known photoinitiator such as trimethyl benzoyl diphenyl phosphine oxide (TPO), but the present invention is not limited thereto.

In the display device according to the present embodiment, since the thin film encapsulation30is formed to have a structure in which the organic layer31and the inorganic layer33are alternately stacked, penetration of oxygen and moisture may be prevented and also flexibility may be secured, and moreover total reflection may be controlled to smoothly occur within the thin film encapsulation30.

Since the organic layer31and the inorganic layer33are formed of materials having different refractive indices, light emitted by the display unit20is not discharged from the outer region B, and reflection repeatedly occurs within the thin film encapsulation30.

In other words, a conventional display device of a top-emission type does not include a structure corresponding to the thin film encapsulation30according to the present embodiment, and thus light loss occurs in the outer region B. Accordingly, the amount of light transmitted to a photosensor is not sufficient and thus the photosensor cannot sense light.

Therefore, in the display device according to the present embodiment, the thin film encapsulation30is formed on the substrate10so that light emitted toward a top side of the display device may be reflected by the organic layer31and the inorganic layer33of the thin film encapsulation30in the outer region B and be confined within the thin film encapsulation30.

In other words, as light is repeatedly reflected by the organic layer31and the inorganic layer33, which are alternately stacked and have different refractive indices, light may not travel toward the top side and only travel toward a lateral side. Consequently, since light travels sideways, sufficient light may be transmitted to the photosensor60according to the present embodiment, which is formed on a lateral side of the thin film encapsulation.

Additionally, since the display device according to the present embodiment includes the thin film encapsulation30, the thin film encapsulation30may further block, along with the encapsulation substrate50, the display unit20from external oxygen and/or moisture.

In other words, the thin film encapsulation30according to the present embodiment may confine light therewithin so that the light is not emitted to the top side, and may protect the display unit20from the outside.

As illustrated inFIG. 2, the photosensor60may be included in the outer region B. For example, in the display device according to the present embodiment, the photosensor60is formed on one end of the thin film encapsulation30.

In the display device according to the present embodiment, the photosensor60may be implemented by using a photodiode, but the present invention is not limited thereto.

The photosensor60senses light and converts energy of the sensed light into electrical energy. The photosensor60is usually used in electronic products and may be employed to accurately measure the intensity of light. Since an output voltage may be generated according to the intensity of sensed light, the photosensor60may measure the intensity of light.

However, when the amount of light transmitted to the photosensor60is not enough, it is difficult to accurately the intensity of light. Thus, to achieve accurate measurement, light that is emitted by the light-emitting device needs to substantially reach the photosensor60.

In a conventional display device, light is reflected by an encapsulation substrate formed in opposite to a substrate, and a photosensor is attached directly to an upper surface the encapsulation substrate or a lower surface of the substrate and receives the reflected light. The encapsulation substrate does not have a total reflection control capability, and accordingly the photosensor receives weak light and thus is not expected to function as a sensor.

On the other hand, in the display device according to the present embodiment, since the thin film encapsulation30is included as illustrated inFIG. 2, light is reflected by the organic layer31and the inorganic layer33of the thin film encapsulation30and travels sideways. Since the photosensor60is formed on one end of the thin film encapsulation30, a sufficient amount of light may be transmitted to the photosensor60.

In other words, since the photosensor60is formed on one end of the thin film encapsulation30, the photosensor60may receive a sufficient amount of light from the lateral side of the thin film encapsulation30. Additionally, since the photosensor60is formed in an empty space within the outer region B, a practical use of a space may increase.

As illustrated inFIG. 2, the encapsulation substrate50may be formed opposite the substrate10in order to protect the display unit20included in the substrate10from external moisture, air, and the like.

The encapsulation substrate50may be formed of the same material as the substrate10, for example, a transparent glass or plastic material.

In the display device according to the present embodiment, the thin film encapsulation30and the encapsulation substrate50, which are formed on the display unit20, may additionally prevent the display unit20from penetration of external moisture, air, and the like.

As illustrated inFIG. 2, to attach the encapsulation substrate50to the upper surface of the thin film encapsulation30, an adhesion layer40may be further formed between the thin film encapsulation30and the encapsulation substrate50.

The adhesion layer40may be located between respective ends of the thin film encapsulation30and the encapsulation substrate50as illustrated inFIG. 2and seal the thin film encapsulation30and the encapsulation substrate50.

The adhesion layer40may include an organic material, such as epoxy, acryl, or silicon, including a light curing material, or an organic and inorganic material in which talc, Ca oxide (CaO), barium oxide (BaO), zeolite, SiO, or the like is included in an organic material. The adhesion layer40may be in a hardened state due to light such as ultraviolet (UV) rays.

In other words, the adhesion layer40may be formed of an adhesive organic, an inorganic material, and a transparent material. The adhesion layer40may block the space between the thin film encapsulation30and the encapsulation substrate50from external moisture or air.

FIG. 4is a cross-sectional view of a display device according to another embodiment. The same reference numerals inFIGS. 1-3andFIG. 4denote the same elements and repeated descriptions thereof are omitted.

In the display device according to the present embodiment, to attach the encapsulation substrate50to the thin film encapsulation30, an adhesion layer41that reflects light may be further formed between the thin film encapsulation30and the encapsulation substrate50.

In the display device according to the present embodiment, the adhesion layer41may include metal particles410.

The metal particles410may be metal, such as Al or Ag having high reflectance. As the adhesion layer41includes the metal particles410having high reflectance, light loss may be reduced.

For example, when the light emitted by the display unit20is totally reflected by the thin film encapsulation30and reaches the adhesion layer41while travelling sideways, the metal particles410included in the adhesion layer41may prevent light from passing therethrough.

When the metal particles410, such as Al or Ag having high reflectance, are included in the adhesion layer41, light that reaches the adhesion layer41may be reflected by the metal particles410back to the thin film encapsulation30.

Thus, in the display device according to the present embodiment, emission of light to the environment via the transparent adhesion layer41, for example, light loss, may be prevented.

FIG. 5is a cross-sectional view of a display device according to another embodiment. The same reference numerals inFIGS. 1-3andFIG. 5denote the same elements and repeated descriptions thereof are omitted.

In the display device according to the present embodiment, to attach the encapsulation substrate50to the thin film encapsulation30, an adhesion layer43may be further formed between the thin film encapsulation30and the encapsulation substrate50, and a reflection layer430may be formed on an upper surface of the adhesion layer43.

The reflection layer430may be in the form of a thin film formed on the upper surface of the adhesion layer43and my reflect light that travels toward the adhesion layer43.

For example, when the light emitted by the display unit20is totally reflected by the thin film encapsulation30and reaches the adhesion layer43while travelling sideways, the light may travel toward the top side, and thus, light loss may occur. To prevent this light loss, the reflection layer430may be formed on the upper surface of the adhesion layer43.

FIGS. 4 and 5illustrate the adhesion layers41and43that are capable of reflecting light incident thereon in order to prevent light loss. However, the present invention is not limited thereto, and any adhesion layer may be included as long as the adhesion layer is formed of a material capable of reflecting light or has a structure capable of reflecting light.

Referring back toFIG. 2, a cover70may be included in the outer region B to surround the display device according to the present embodiment.

The cover70corresponds to a frame of a TV, a bezel of a mobile phone, or the like. The cover70may be formed to surround the display device in order to prevent users from seeing internal wiring, circuits, and other unnecessary structures.

Moreover, since the cover70surrounds the display device, the display device may be provided in a rigid and strong state.

As described above, according to at least one of the disclosed embodiments, in a top-emission type display device, light loss is prevented, and a sufficient amount of light is transmitted to a photosensor.