DISPLAY APPARATUS

A display device including a plurality of pixels disposed on a substrate, in which each pixel includes a first subpixel, a second subpixel adjacent to the first subpixel, and a third subpixel adjacent to the second subpixel, the second subpixel disposed between the first subpixel and the third subpixel; a first color filter disposed in the first subpixel, and configured to emit light having a first color; a second color filter disposed in the second subpixel, and configured to emit light having a second color; and a third color filter disposed in the third subpixel, and configured to emit light having a third color. Further, an upper surface of the second color filter is disposed a greater distance from the substrate than an upper surface of the first color filter, and the first subpixel further includes a first light path changing layer disposed on the first color filter and contacting a first side surface of the second color filter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of the Korean Patent Application No. 10-2021-0193009, filed on Dec. 30, 2021, the entire contents of which are hereby expressly incorporated by reference into the present application.

BACKGROUND

Field of the Invention

The present disclosure relates to a display apparatus for displaying an image.

Discussion of the Related Art

With the advancement of the information age, the demand for a display apparatus for displaying an image has increased. Therefore, different display apparatuses such as a liquid crystal display (LCD) device, a plasma display panel (PDP) device, an organic light emitting display (OLED) device, and a quantum dot light emitting display (QLED) device have been recently used.

Among the display apparatuses, OLED and QLED devices are self-light emitting types, and have advantages in that a viewing angle and a contrast ratio are improved compared to the LCD device. Also, because the OLED and QLED devices do not require a separate backlight unit, the devices can be advantageously thin and lightweight and also have low power consumption.

Recently, an organic light emitting display apparatus having densely disposed pixels to implement high resolution has been developed. However, when an interval between the pixels is too narrow, current can leak from a pixel for emitting light to an adjacent pixel not used for emitting light. Thus, light can be emitted from the adjacent pixel due to the leakage current thereby causing a color mixture. In addition, the narrow interval between the pixels makes it more difficult to change a structure for improving light efficiency.

SUMMARY OF THE DISCLOSURE

Accordingly, one object of the present disclosure is to address the above-noted and other problems.

Another object of the present disclosure is to provide a display apparatus that improves light efficiency and prevents a color mixture from occurring.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, the present invention provides in one aspect a display device including a plurality of pixels disposed on a substrate, in which each pixel includes a first subpixel, a second subpixel adjacent to the first subpixel, and a third subpixel adjacent to the second subpixel, the second subpixel disposed between the first subpixel and the third subpixel; a first color filter disposed in the first subpixel, and configured to emit light having a first color; a second color filter disposed in the second subpixel, and configured to emit light having a second color; and a third color filter disposed in the third subpixel, and configured to emit light having a third color. Further, an upper surface of the second color filter is disposed a greater distance from the substrate than an upper surface of the first color filter, and the first subpixel further includes a first light path changing layer disposed on the first color filter and contacting a first side surface of the second color filter.

DETAILED DESCRIPTION OF THE EMBODIMENTS

When ‘comprise,’ ‘have,’ and ‘include’ described in the present specification are used, another part can be added unless ‘only˜’ is used. The terms of a singular form can include plural forms unless referred to the contrary. In construing an element, the element is construed as including an error range although there is no explicit description. In describing a position relationship, for example, when a position relation between two parts is described as ‘on˜,’ ‘over˜,’ ‘under˜,’ and ‘next˜,’ one or more other parts can be disposed between the two parts unless ‘just’ or ‘direct’ is used.

In describing a temporal relationship, for example, when the temporal order is described as “after,” “subsequent,” “next,” and “before,” a case which is not continuous can be included, unless “just” or “direct” is used. Although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure.

“X-axis direction,” “Y-axis direction” and “Z-axis direction” should not be construed by a geometric relation only of a mutual vertical relation and can have broader directionality within the range that elements of the present disclosure can act functionally. The term “at least one” should be understood as including all combinations of one or more of the associated listed items. For example, the meaning of “at least one of a first item, a second item and a third item” denotes the combination of all items proposed from two or more of the first item, the second item and the third item as well as the first item, the second item or the third item.

Features of various embodiments of the present disclosure can be partially or overall coupled to or combined with each other and can be variously inter-operated with each other and driven technically as those skilled in the art can sufficiently understand. The embodiments of the present disclosure can be performed independently from each other or can be performed together in co-dependent relationship.

Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In particular,FIG.1is a schematic plan view illustrating a display apparatus,FIG.2is a cross-sectional view taken along line I-I′ shown inFIG.1, andFIG.3is an enlarged view illustrating a portion A ofFIG.2according to an embodiment of the present invention.

As shown,FIGS.1-3illustrate a display apparatus100including a substrate110having a plurality of subpixels, a color filter130and a light path changing layer150. The substrate110includes pixels P, each of which can include a plurality of subpixels. For example, as shown inFIG.1, the plurality of subpixels can include a first subpixel SP1provided on the substrate110, a second subpixel SP2adjacent to the first subpixel SP1, and a third subpixel SP3adjacent to the second subpixel SP2. As shown, the subpixels SP1, SP2and SP3are disposed adjacent to one another in a first direction, which is a horizontal direction inFIG.1. The horizontal direction can be a direction in which a signal line SL (shown inFIG.2) of the display apparatus100is disposed. In one example, the signal line SL can be a gate line.

In addition, the color filter130converts or filters light emitted from an organic light emitting layer116provided between the substrate110and the color filter130into a color of a corresponding subpixel. InFIG.1, the color filter130includes a first color filter131in the first subpixel SP1, a second color filter132in the second subpixel SP2, and a third color filter133in the third subpixel SP3. For example, the first color filter131can be a red color filter that converts white light incident from an organic light emitting layer116into red light. The second color filter132can be a green color filter that converts the white light incident from the organic light emitting layer116into green light, and the third color filter133can be a blue color filter that converts the white light incident from the organic light emitting layer116into blue light.

When the red, green and blue light respectively emitted through the first, second and third color filters131,132and133are mixed, a user views white light. Further, each color filter130can include an upper surface, and first and second sides connected to the upper surface. For example, as shown inFIG.2, the first color filter131includes an upper surface131apositioned toward a second substrate190, and a side131bconnected to the upper surface131a.Also, the second color filter132includes an upper surface132apositioned toward the second substrate190, and a side132bconnected to the upper surface132a,and the third color filter133includes an upper surface133apositioned toward the second substrate190, and a side133bconnected to the upper surface133a.

In addition, as shown inFIG.2, the display apparatus100includes a light path changing layer150on a side of one or more of the color filters131,132and133. The light path changing layer150changes a path of light emitted through the color filter130. For example, the light path changing layer150changes a light path so that side light L1emitted toward the subpixel adjacent to the subpixel emitting light is changed to be emitted toward the subpixel emitting light.

Further, the light path changing layer150includes a refractive index different from that of the color filter130, thereby changing a path of light incident from the color filter130. For example, the light path changing layer150can have a refractive index smaller or lower than that of the color filter130, so that the side light L1emitted from the subpixel towards its adjacent subpixel can be changed to light L2(or front light L2) emitted toward the subpixel for emitting light as shown inFIG.2. The light path changing layer150according to an example can be air, but is not limited thereto, and may be another material having a refractive index smaller or lower than that of the color filter130.

Therefore, as the display apparatus100includes a light path changing layer150adjacent to a side of the color filter130, the side light L1emitted toward the adjacent non-emitting subpixel can be changed and converted into the front light L2, whereby the front light efficiency of the subpixel emitting light can be improved.

Referring toFIG.2, the substrate110includes a thin film transistor, and may be a transistor array substrate, a lower substrate, a base substrate, or a first substrate, for example. The substrate110may be a transparent glass substrate, a transparent plastic substrate, or a silicon wafer substrate. Hereinafter, the substrate110will be defined as a first substrate. An opposite substrate190can be provided on the first substrate110.

For example, the opposite substrate190can be bonded to a first surface or upper surface of the first substrate110via an adhesive layer180(FIG.7). The opposite substrate190can also have a size smaller than that of the first substrate110, and be bonded to the other portion except a pad portion of the first substrate110. The opposite substrate190can also be an upper substrate, a second substrate, or an encapsulation substrate. Hereinafter, the opposite substrate190will be defined as the second substrate.

In addition, the first substrate110according to an example may include a plurality of subpixels. For example, as shown inFIG.1, the first substrate110may include a first subpixel SP1, a second subpixel SP2adjacent to the first subpixel SP1, and a third subpixel SP3adjacent to the second subpixel SP2. The first, second and third subpixels according to an example emit red, green and blue light, respectively. Each subpixel SP1, SP2and SP3can also be defined as an area of a minimum unit in which light is actually emitted.

Further, each subpixel SP1, SP2and SP3includes a thin film transistor and a light emitting element connected to the thin film transistor.FIG.2illustrates the light emitting element including the organic light emitting layer116interposed between a first electrode114and a second electrode117. As shown, the organic light emitting layer116is a common layer commonly deposited on the subpixels SP1, SP2and SP3.

In addition, in one embodiment, the organic light emitting layer116emits white light. In more detail, the organic light emitting layer116may include a plurality of stacks that emit light of different colors. For example, as shown inFIGS.2and3, the organic light emitting layer116may include a first stack1161, a second stack1163, and a charge generation layer (CGL)1162provided between the first stack1161and the second stack1163. Because the organic light emitting layer emits white light, each subpixel SP1, SP2and SP3may include the color filter130matched with a corresponding color. Because the color filter130converts or filters the white light emitted from the organic light emitting layer116, the color filter130is disposed on the organic light emitting layer116.

In addition, as shown inFIG.2, each subpixel SP1, SP2and SP3can include a buffer layer BL disposed on the first substrate110to prevent moisture permeation to the thin film transistor112. Each subpixel also includes an inorganic layer111provided on an upper surface of the buffer layer BL. The inorganic layer111includes a gate insulating layer111a,an interlayer insulating layer111band a passivation layer111c.Each subpixel also includes a planarization layer113provided on the inorganic layer111, a first electrode114provided on the planarization layer113, a bank115, the organic light emitting layer116, a second electrode117, and an encapsulation layer118.

In addition, a thin film transistor112for driving the subpixel can be disposed in the inorganic layer111, and thus the inorganic layer111can be called a circuit element layer. Also, the buffer layer BL may be included in the inorganic layer111along with the gate insulating layer111a,the interlayer insulating layer111band the passivation layer111c.The first electrode114, the organic light emitting layer116and the second electrode117can also be included in the light emitting element.

The light emitting element is also electrically connected to a signal line SL provided on the first substrate110. For example, as shown inFIG.2, the first electrode114is electrically connected to the signal line SL by being connected to the thin film transistor112. A source electrode112cor a drain electrode112dincluded in the thin film transistor112may be connected to the signal line SL.

In addition, the signal line SL is for applying a signal or power source for driving each subpixel SP1, SP2and SP3, and according to one example may be a gate line. As shown inFIG.2, the signal line SL is provided between the first substrate110and the buffer layer BL, but the buffer layer BL can be disposed in another layer. Each subpixel SP1, SP2and SP3is also driven to emit light in accordance with a signal applied from the signal line SL.

Further, as shown inFIG.2, the buffer layer BL is formed between the first substrate110and the gate insulating layer111ato protect the thin film transistor112. The buffer layer BL can also be disposed entirely on one surface (or front surface) of the first substrate110. The buffer layer BL prevents a material contained in the first substrate110from being diffused into a transistor layer during a high temperature thin film transistor manufacturing process. Optionally, the buffer layer BL can be omitted.

In addition, as shown inFIG.2, the thin film transistor112according to an example may include an active layer112a,a gate electrode112b,a source electrode112c,and a drain electrode112d.The active layer112aincludes a channel area, a drain area and a source area, which are formed in a thin film transistor area of a circuit area of the subpixel SP. Further, the drain area and the source area are spaced apart from each other with the channel area interposed therebetween.

Also, the active layer112amay include a semiconductor material based on any one of amorphous silicon, polycrystalline silicon, oxide and organic material, for example. When the first substrate110is a silicon wafer substrate, an active layer112acan be formed in the silicon wafer substrate.

As shown inFIG.2, the gate insulating layer111ais formed on the channel area of the active layer112a.As an example, the gate insulating layer111acan be formed in an island shape only on the channel area of the active layer112a,or can be formed on an entire front surface of the first substrate110or the buffer layer BL, which includes the active layer112a.The gate electrode112bcan also be formed on the gate insulating layer111ato overlap the channel area111cof the active layer112a.

The interlayer insulating layer111bis formed on the gate electrode112band the drain area and the source area of the active layer112a.The interlayer insulating layer111bcan be formed in the circuit area and an entire light emission area, in which light is emitted to the pixel P. For example, the interlayer insulating layer111bmay be made of an inorganic material but is not limited thereto.

Further, as shown inFIG.2, the source electrode112cis electrically connected to the source area of the active layer112athrough a source contact hole provided in the interlayer insulating layer111boverlapped with the source area of the active layer112a.The drain electrode112dis also electrically connected to the drain area of the active layer112athrough a drain contact hole provided in the interlayer insulating layer111boverlapped with the drain area of the active layer112a.

The drain electrode112dand the source electrode112cmay be made of the same metal material. For example, each of the drain electrode112dand the source electrode112cmay be made of a single metal layer, a single layer of an alloy or a multi-layer of two or more layers, which is the same as or different from that of the gate electrode.

In addition, the circuit area may further include first and second switching thin film transistors disposed together with the thin film transistor112, and a capacitor. Each of the first and second switching thin film transistors is provided on the circuit area of the pixel P to have the same or similar structure as that of the thin film transistor112. Also, the capacitor can be provided in an overlap area between the gate electrode112band the source electrode112cof the thin film transistor112, which overlap each other with the interlayer insulating layer111binterposed therebetween.

Additionally, to prevent a threshold voltage of the thin film transistor provided in a pixel area from being shifted by light, the display panel or the first substrate110may further include a light shielding layer provided below the active layer112aof at least one of the thin film transistor112, the first switching thin film transistor or the second switching thin film transistor. The light shielding layer can be disposed between the first substrate110and the active layer112ato shield light incident on the active layer112athrough the first substrate110, thereby minimizing a change in the threshold voltage of the transistor due to external light.

Further, the protective layer111cis provided on the first substrate110to cover the pixel area. In particular, the protective layer111ccovers the drain electrode112dand the source electrode112cof the thin film transistor112and the interlayer insulating layer111b.The protective layer111ccan be entirely formed in the circuit area and the light emission area and be expressed as a passivation layer. The protective layer111ccan also be omitted.

As shown inFIG.2, the planarization layer113is formed on the first substrate110to cover the protective layer111c.When the protective layer111cis omitted, the planarization layer113can be provided on the first substrate110to cover the circuit area. The planarization layer113can also be formed entirely in the circuit area and the light emission area.

Also, the planarization layer113according to one example can be formed to be relatively thick to provide a display area DA including a plurality of subpixels. The planarization layer113can be made of an organic material such as photo acryl, benzocyclobutene, polyimide, and fluorine resin, for example.

In addition, as shown inFIG.2, the first electrode114of the subpixel SP is formed on the planarization layer113. The first electrode114is also connected to the drain electrode or the source electrode of the thin film transistor112through a contact hole passing through the planarization layer113and the protective layer111c.

Further, the first electrode114may be made of at least one of a transparent metal material, a semi-transmissive metal material, or a metal material having a high reflectance. When the display apparatus100is provided in a top emission mode, the first electrode114can be formed of a metal material having a high reflectance or a stacked structure of a metal material having a high reflectance and a transparent metal material. For example, the first electrode114can be formed of a metal material having a high reflectance, such as a stacked structure (Ti/Al/Ti) of aluminum and titanium, a stacked structure (ITO/Al/ITO) of aluminum and ITO, an Ag alloy, and a stacked structure (ITO/Ag alloy/ITO) of Ag alloy and ITO. The Ag alloy may be an alloy such as silver (Ag), palladium (Pd), and copper (Cu).

When the display apparatus100is provided in a bottom emission mode, the first electrode114may be formed of a transparent conductive material (TCO) such as ITO and IZO, which can transmit light, or a semi-transmissive conductive material such as magnesium (Mg), silver (Ag) or an alloy of magnesium (Mg) and silver (Ag). Also, the material constituting the first electrode114may include MoTi, and the first electrode114may be an anode electrode or a pixel electrode.

In addition, as shown inFIG.2, the first electrode114includes a first sub-electrode1141provided in the first subpixel SP1, a second sub-electrode1142provided in the second subpixel SP2, and a third sub-electrode1143provided in the third subpixel SP3. In the display apparatus100according to one embodiment of the present disclosure, one or more of the first sub-electrode1141, the second sub-electrode1142and the third sub-electrode1143is provided to be higher than another sub-electrode.

As one or more of the sub-electrodes1141,1142and1143are disposed higher than the other sub-electrodes, the color filter disposed on the higher sub-electrode is disposed higher than the other color filters. Therefore, a side of the higher color filter can be in contact with the light path changing layer150and thus the side light can be converted into the front light to improve the front light efficiency. Further, the sub-electrode disposed higher means a distance from an upper surface of the first substrate110to an upper surface (or lower surface) of the sub-electrode is longer than other sub-electrodes. Likewise, the color filter disposed to be higher means a distance from the upper surface of the first substrate110to an upper surface (or lower surface) of the color filter is longer than other color filters.

For example, as shown inFIG.2, a height E2H of the second sub-electrode1142is higher than a height E1H of the first sub-electrode1141and/or the third sub-electrode1143. Therefore, a height H2of the second color filter132disposed in the second sub-electrode1142is higher than a height H1of the first color filter131and/or the third color filter133. Thus, the light path changing layer150is in contact with at least a portion of a side132bof the second color filter132(i.e., a green color filter).

As the light path changing layer150is in contact with the side132bof the second color filter132, the side light L1emitted toward the first subpixel SP1and/or the second subpixel SP2can be converted or reflected into front light L2to improve the front light efficiency. As described above, because the refractive index of the light path changing layer150is less than that of the second color filter132, the side light L1can be totally reflected on a boundary surface between the side132bof the second color filter132and the light path changing layer150, whereby the side light L1is converted or changed into the front light L2.

In addition, the second color filter132is preferably disposed higher than the other color filters131and133because the luminance of green light is lower than of the illuminance of red light and blue light. For example, as the red light, the green light and the blue light are mixed, a user can view white light. When the luminance of the green light is lower than that of each of the red light and the blue light, the color purity of the white light is lowered, and a yellowish white light may be viewed by the user. Therefore, the green color filter132is disposed to be higher than the other color filters131and133, and the light path changing layer150is disposed on the side132bof the green color filter132to improve luminance of the green light, whereby white light with a higher color purity can be implemented.

In addition, the light path changing layer150is disposed on the side132bof the second color filter132and contacts the upper surface131aof the first color filter131and the upper surface133aof the third color filter133. However, the present disclosure is not limited to the above structure, and when the luminance of the red light is lower than that of each of the green light and the blue light, the first color filter131can be disposed to be higher, and the light path changing layer150can be disposed on the side131bof the first color filter131. Likewise, when the luminance of the blue light is lower than that of each of the red light and the green light, the third color filter133can be disposed to be higher, and the light path changing layer150can be disposed on the side133bof the third color filter133.

Referring again toFIG.2, the bank115is a non-light emission area in which light is not emitted, and is provided to surround each of light emission areas of the plurality of subpixels SP1, SP2and SP3. That is, the bank115partition or defines the respective light emission areas. Accordingly, the bank115is disposed at a boundary between the plurality of subpixels SP1, SP2, and SP3.

Further, inFIG.2, the bank115is formed on the planarization layer113to cover an edge portion of the first electrode114, thereby partitioning or defining a light emission area of each subpixel. The bank115can also be formed to cover the edge portion of the first electrode114of each of the subpixels SP and expose a portion (e.g., a central portion) of the first electrode114. The portion exposed without being covered by the bank115is the light emission area. As the bank115covers the edge of the first electrode114, the bank115prevents light emitting efficiency from being deteriorated due to a current concentration on each end of the first electrode114. The bank115also prevents the first electrode114and the second electrode117from being shorted due to the thickness of the organic light emitting layer, which is thin at the edge of the first electrode114.

Also, according to an embodiment of the present disclosure, the bank115preferably has a stacked structure (e.g., a two stacked structure) so one or more of the first electrodes114of the plurality of subpixels is disposed higher, thereby disposing the corresponding color filter to be higher than the other color filters. In addition, as discussed above, the side of the higher color filter contacts the light path changing layer150, and thus the side light can be converted into the front light to improve the front light efficiency. The bank115according to an example inFIG.2includes a first bank1151and a second bank1152provided on the first bank1151. The bank115may be formed of an organic layer such as an acrylic resin, an epoxy resin, a phenolic resin, a polyamide resin, and a polyimide resin, but is not limited thereto.

As shown inFIG.2, the organic light emitting layer116is formed to cover the first electrode114and the bank115and in one example, is provided to emit white light. As shown inFIG.3, the organic light emitting layer116may include a first stack1161, a second stack1163, and a charge generation layer (CGL)1162provided between the first stack1161and the second stack1163.

Also, the first stack1161is provided on the first electrode114and may include a hole injecting layer (HIL), a hole transporting layer (HTL), a blue light emitting layer ((EML)B), and an electron transporting layer (ETL) sequentially stacked. Further, the charge generation layer1162supplies charges to the first stack1161and the second stack1163. In one example, the charge generation layer1162also includes an N-type charge generation layer for supplying electrons to the first stack1161, and a P-type charge generation layer for supplying holes to the second stack1163. The N-type charge generation layer may also include a metal material as a dopant. In addition, the second stack1163is provided on the first stack1161and may include a hole transporting layer (HTL), a yellow green (YG) emitting layer (EML(YG)), an electron transporting layer (ETL) and an electron injecting layer (EIL) are sequentially stacked.

As shown inFIG.2, because the organic light emitting layer116is provided as a common layer, the first stack1161, the charge generation layer and the second stack1163can be disposed over all the subpixels SP1, SP2and SP3. In addition, the second electrode117is formed on the organic light emitting layer116and may be a common layer commonly formed in the subpixels SP1, SP2, and SP3. The second electrode117can also be made of a transparent metal material, a semi-transmissive metal material or a metal material having high reflectance.

When the display apparatus100is provided in a top emission mode, the second electrode117may be formed of a transparent conductive material (TCO) such as ITO and IZO, which can transmit light, or a semi-transmissive conductive material such as magnesium (Mg), silver (Ag) or an alloy of magnesium (Mg) and silver (Ag). When the transparent display apparatus100is provided in a bottom emission mode, the second electrode117may be formed of a metal material having a high reflectance, such as a stacked structure (Ti/Al/Ti) of aluminum and titanium, a stacked structure (ITO/Al/ITO) of aluminum and ITO, an Ag alloy and a stacked structure (ITO/Ag alloy/ITO) of Ag alloy and ITO. The Ag alloy may be an alloy of silver (Ag), palladium (Pd), copper (Cu), etc. Also, the second electrode117may be a counter electrode or a cathode electrode.

In addition, the encapsulation layer118is formed on the second electrode117and prevents oxygen or water from permeating into the organic light emitting layer116and the second electrode117. Thus, the encapsulation layer118may include at least one inorganic layer.

Also, the color filter130is disposed on the encapsulation layer118. As described above, the color filter130may include a red color filter131provided in the first subpixel SP1, a green color filter132provided in the second subpixel SP2, and a blue color filter133provided in the third subpixel SP3.

As shown inFIG.2, the upper layer170is disposed on the color filter130and is used to bond the second substrate190to the first substrate110. Thus, the upper layer170according to an example may be a double-sided tape. After the upper layer170is attached onto the second substrate190, the upper layer170can be attached to one or more of the plurality of color filters130to bond the second substrate190to the first substrate110.

As shown inFIG.2, because the light path changing layer150is disposed adjacent to the side of the highest placed color filter130, the upper layer170is attached to the light path changing layer150. Therefore, the upper layer170contacts an upper surface of the color filter130and an upper surface of the light path changing layer150. The second substrate190is also disposed on the upper layer170.

Referring toFIG.2, the organic light emitting layer116is a common layer in a plurality of subpixels. When the organic light emitting layer is commonly provided, the current in the light emitting subpixel may leak toward an adjacent non-light emitting subpixel along the organic light emitting layer, so that a color mixture is generated.

However, according to an embodiment of the present disclosure, a height of the bank115can be increased to increase a length of the organic light emitting layer116disposed between the light emission areas of the respective subpixels. That is, a length of a current path through the organic light emitting layer is increased. As the length of the organic light emitting layer116is increased, the amount of the current reaching the adjacent subpixel becomes smaller, so that the adjacent subpixel does not emit light, and a color mixture can be avoided.

Thus, the display apparatus100according to one embodiment of the present disclosure includes a first bank1151disposed on an upper surface of the planarization layer113, and a second bank1152disposed on the first bank1151. As the second bank1152is disposed on the first bank1151, the overall height of the bank115is increased, so that the length of the organic light emitting layer116disposed between the light emission areas of the subpixels is also lengthened. Therefore, the length of the current path for reducing or blocking the leakage current can be increased.

As shown inFIG.3, the bank115includes a taper TP. In more detail, after the first electrode114is formed on the planarization layer113, the bank115can be formed by depositing and patterning a material constituting the bank115(e.g., using a photo process with a mask and an etching process). As the material constituting the bank115is patterned by the photo process and the etching process, the bank115includes an angled edge-shaped taper TP having an inclined surface connected to the first electrode114as shown inFIG.3.

Because the display apparatus100includes two or more banks, that is, a first bank1151, and a second bank1152disposed on the first bank1151, the taper TP can be provided in the second bank1152positioned on the upper side. Due to the taper TP included in the bank115, the organic light emitting layer116formed entirely in a subsequent process can have a thinner thickness in a portion where the taper TP is disposed. For example, as shown inFIG.3, a thickness T1of the organic light emitting layer116overlapped with the taper TP in a thickness direction of the first substrate110is thinner than a thickness T2of the organic light emitting layer116not overlapped with the taper TP. Because the organic light emitting layer116has a step coverage lower than that of a metal material, its thickness can be thinner on the edge portion of the taper TP and/or the inclined surface of the taper TP.

In the display apparatus100according to one embodiment of the present disclosure, the bank115is provided to include the taper TP, so that the thickness of the organic light emitting layer116is thinner in a taper area in which the taper TP is provided. Because the resistance of the organic light emitting layer116or charge generation layer is increased in a portion where the thickness of the organic light emitting layer116becomes thinner, the current can be prevented from leaking from the subpixel for emitting light to the subpixel for not emitting light. Therefore, a color mixture between the subpixels caused by the leakage current can be prevented.

Referring again toFIG.2, so one or more of the plurality of color filters131,132and133are disposed to be higher than the other color filter(s), one or more of the plurality of sub-electrodes1141,1142and1143is provided to be higher. For example, as shown inFIG.2, when the height of the second color filter132is higher than that of the first color filter131and/or the third color filter133, the height of the second sub-electrode1142is higher than that of the first sub-electrode1141and/or the third sub-electrode1143. In this example, the first bank1151covers the edge of each of the first sub-electrode1141and/or the third sub-electrode1143. Therefore, the first bank1151contacts the edge of each of the first sub-electrode1141and/or the third sub-electrode1143.

To dispose the second sub-electrode1142to be higher, the first bank1151can be provided entirely over the second subpixel SP2. Therefore, the first bank1151partially covers a connection electrode CE connected to the thin film transistor112. Because the connection electrode CE is disposed on the upper surface of the planarization layer113, the connection electrode CE can be provided in the same layer as the first sub-electrode1141and/or the third sub-electrode1143.

In addition, one side of the connection electrode CE according to an example can be connected to the source electrode112cor the drain electrode112dof the thin film transistor112through a contact hole passing through the planarization layer113and the passivation layer111c.Also, the other side of the connection electrode CE can contact the lower surface of the second sub-electrode1142through a contact hole passing through the first bank1151. Therefore, the connection electrode CE can be electrically connected to the second sub-electrode1142to transfer the signal or power source applied from the signal line SL to the second sub-electrode1142.

As the second sub-electrode1142is disposed on the upper surface of the first bank1151disposed in the second subpixel SP2, the second sub-electrode1142is disposed higher than the other sub-electrodes1141and1143. The second bank1152also covers the edge of the second sub-electrode1142on the first bank1151. Therefore, the second bank1152contacts the edge of the second sub-electrode1142.

Also, the organic light emitting layer116formed in the subsequent process can be provided as a common layer to cover the second sub-electrode1142disposed on the first bank1151in the second subpixel SP2, the first sub-electrode1141disposed on the planarization layer113in the first subpixel SP1, the third sub-electrode1143disposed on the planarization layer113in the third subpixel SP3, the first bank1151and the second bank1152.

Further, the encapsulation layer118for preventing moisture permeation is formed on the organic light emitting layer116. Because the encapsulation layer118is formed along a profile of the organic light emitting layer116, the encapsulation layer118can be provided in the plurality of subpixels at the same thickness. As shown inFIG.2, because the second sub-electrode1142is higher than the other sub-electrodes1141and1143, the encapsulation layer118formed on the second sub-electrode1142is disposed higher than the encapsulation layer118formed on the other sub-electrodes1141and1143.

The color filter130is also disposed on the encapsulation layer118. Because the color filter130is formed along a profile of the encapsulation layer118, as shown inFIG.2, the second color filter132is disposed higher than the first color filter131and/or the third color filter133. That is, the upper surface131aof the first color filter131is disposed higher than the upper surface132aof the second color filter132and the upper surface133aof the third color filter133. Therefore, a portion of the side132bof the second color filter132protrudes more toward the second substrate190than the upper surface131aof the first color filter131and/or the upper surface133aof the third color filter133, and thus is in contact with the light path changing layer150formed in the subsequent process. In this instance, the portion of the side132bof the second color filter132corresponds to a portion that is not in contact with the side131bof the first color filter131and/or the side133bof the third color filter133, or a portion that is not overlapped with the side131band/or the side133bin the first direction. Also, the first direction refers to a direction parallel with the upper surface of the first substrate110or a direction in which the first subpixel SP1and the second subpixel SP2are adjacent to each other.

As a portion of the side132aof the second color filter132contacts the light path changing layer150, the side light L1can be converted into the front light L2by total reflection due to a difference in a reflective index on a boundary surface between the portion of the side132aof the second color filter132and the light path changing layer150. In this instance, the conversion or change means the path of light or the direction of light is changed. Therefore, because the side light L1emitted toward the adjacent subpixel SP is converted into the front light L2, the front light efficiency of each subpixel can be improved.

In addition, as the second sub-electrode1142is provided to be higher than the first sub-electrode1141and/or the third sub-electrode1143, the length between the first sub-electrode1141and the second sub-electrode1142is increased compared with the sub-electrodes having the same height. Because the path of the organic light emitting layer116provided between the first sub-electrode1141and the second sub-electrode1142is longer than the sub-electrodes having the same height, the leakage current to the adjacent subpixel can be reduced or avoided. In addition, because the thickness of the organic light emitting layer116is reduced in the taper area due to the taper TP of the bank115, the resistance of the organic light emitting layer116can be increased, whereby decrease and blocking of the leakage current can be maximized, and thus a color mixture between the subpixels can be avoided.

Next,FIG.4is a schematic cross-sectional view illustrating a display apparatus according to another embodiment of the present disclosure. Referring toFIG.4, the display apparatus100is like the display apparatus ofFIG.2except that the height of the color filter130is changed according to a structure change of the encapsulation layer118. Therefore, the same reference numerals are given for the same elements, and elements different from those ofFIG.2are described.

InFIG.2, the encapsulation layer118having the same thickness is formed on the organic light emitting layer116, so that the side132bof the second color filter132, the side131bof the first color filter131and the side133bof the third color filter133are overlapped with one another as much as about 50% in the first direction. Therefore, in the side132bof the second color filter132, which is not overlapped with the side131bof the first color filter131and/or the side133bof the third color filter133, the light path can be converted into the front light due to a difference in a refractive index with the light path changing layer150, whereby front light efficiency may be improved.

However, inFIG.4, the encapsulation layer118provided in the first subpixel SP1and the third subpixel SP3is further etched or patterned in the second direction toward the first substrate110from the second substrate190. Therefore, a thickness EC2T of the encapsulation layer118between the second color filter132and the first substrate110or the second sub-electrode1142is thicker than a thickness EC1T of the encapsulation layer118between the first color filter131and the first substrate110(or the first sub-electrode1141). Alternatively, the thickness EC2T of the encapsulation layer118between the second color filter132and the first substrate110or the second sub-electrode1142can be thicker than a thickness of the encapsulation layer118between the third color filter133and the first substrate110or the third sub-electrode1143.

In the display apparatus ofFIG.4, because the position of each of the first color filter131and the third color filter133is lowered in the second direction as much as the thickness of the encapsulation layer118patterned in the first subpixel SP1and the third subpixel SP3, a length of an overlap area OA in which the side132bof the second color filter132and the side131bof the first color filter131overlap each other in the first direction is shortened. For example, in the display apparatus100according to the embodiment inFIG.4, an overlap ratio of the side132bof the second color filter132and the side131bof the first color filter131in the first direction is less than 50%. Because an overlap ratio of the side132bof the second color filter132and the light path changing layer150in the first direction is 50% or more, for example, 80% or more as shown inFIG.4, the length of the boundary surface where the side132bof the color filter132contacts the light path changing layer150can be increased. As a result, because the amount of light capable of converting the side light L2into the front light L1can be increased, the front light efficiency can be further increased.

Further, the encapsulation layer118is provided to be thinner in one or more of the plurality of subpixels, so that the height of the upper surface of the color filter disposed on the thin encapsulation layer118can be lower than the height of the upper surface of the color filter disposed in the other subpixel. For example, as shown inFIG.4, the height of the upper surface131aof the first color filter131and/or the upper surface133aof the third color filter133is lower than the display apparatus ofFIG.2. However, even in the display apparatus100shown inFIG.4, the light path changing layer150can be disposed to contact the side132bof the second color filter132and the upper surface131aof the first color filter131and/or the upper surface133aof the third color filter133in the same manner as the display apparatus ofFIG.2. For the display apparatus100shown inFIG.4, because the second color filter132protrudes more toward the second substrate190than the display apparatus shown inFIG.2, the thickness of the light path changing layer150is thicker than that of the light path changing layer ofFIG.2.

Although the encapsulation layer118is further patterned to increase the boundary surface between the side132bof the second color filter132and the light path changing layer150, the present disclosure is not limited thereto, and the second sub-electrode132can be disposed higher than the second sub-electrode132ofFIG.2without patterning of the encapsulation layer118. Therefore, the boundary surface between the side132bof the second color filter132and the light path changing layer150can be increased. In this instance, the second sub-electrode132is disposed on the second bank1152and an edge of the second sub-electrode132can be covered by another bank disposed on the second bank1152.

Next,FIG.5is a schematic cross-sectional view illustrating a display apparatus according to another embodiment of the present disclosure. The display apparatus100inFIG.5is the same as the display apparatus ofFIG.2except that the sub-electrodes and the color filter130disposed thereon are changed to a stepwise structure. Therefore, the same reference numerals are given for the same elements, and elements different from those ofFIG.1are described. For convenience of description, side light emitted from the subpixel to one side is only shown inFIG.5.

InFIG.2, the first sub-electrode131and the third sub-electrode133are provided on the upper surface of the planarization layer113, and the second sub-electrode132is provided on the upper surface of the first bank1151, so that the second color filter132can be disposed higher than the first color filter131and the third color filter133. Therefore, the light path can be changed or converted on the boundary surface between the side132bof the second color filter132and the light path changing layer150. Accordingly, the front light efficiency of the green light can be improved.

On the other hand, inFIG.5, the first color filter131, the second color filter132and the third color filter133are provided in a stepwise structure. In particular, the first sub-electrode1141disposed below the first color filter131, the second sub-electrode1142disposed below the second color filter132and the third sub-electrode1143disposed below the third color filter133are provided in a stepwise manner in which the layers disposed below the respective sub-electrodes are provided differently from one another. For example, as shown inFIG.5, the first sub-electrode1141is provided on the upper surface of the planarization layer113, the second sub-electrode1142is provided on the upper surface of the first bank1151on the planarization layer113, and the third sub-electrode1143is provided on the upper surface of the second bank1152on the first bank1151. Therefore, the height E2H of the second sub-electrode1142is higher than the height E1H of the first sub-electrode1141, and is lower than the height E3H of the third sub-electrode1143.

After the sub-electrodes are formed in the stepwise structure as described above, the organic light emitting layer116, the second electrode117, the encapsulation layer118, the color filter130, and the light path changing layer150are sequentially formed, and the light path changing layer150is provided on the side132bof the second color filter132and the side133bof the third color filter133. In this instance, the light path changing layer150has a structural characteristic in which it is disposed on the upper surface131aof the first color filter131and the upper surface132aof the second color filter132. Therefore, the light path can be changed toward the front surface directed toward the second substrate190even on the side133bof the third color filter133adjacent to the light path changing layer150as well as the side132bof the second color filter132adjacent to the light path changing layer150.

To planarize the upper layer170formed on the color filter130, the thickness of the light path changing layer150on the upper surface131aof the first color filter131and the side132bof the second color filter132can be thicker than that of the light path changing layer150on the upper surface132aof the second color filter132and the side133bof the third color filter133. Further, the upper layer170can be planarized to prevent a gap with the second substrate190from occurring. When the gap occurs between the upper layer170and the second substrate190, the second substrate190having an encapsulation function can be easily damaged due to an external impact thereby reducing a moisture permeable function. Thus, the reliability of the display apparatus may be deteriorated. Therefore, in the display apparatus100according to the embodiment inFIG.5, as the light path changing layer150overlapped with the first subpixel SP1is thicker than the light path changing layer150overlapped with the second subpixel SP2, the gap can be prevented from being formed between the upper layer170and the second substrate190, to improve the reliability.

Referring again toFIG.5, the bank115includes a first bank1151, a second bank1152disposed on the first bank1151and a third bank1153disposed on the second bank1152. The first bank1151contacts an edge of the first sub-electrode1141by covering the edge of the first sub-electrode1141. Also, the second bank1152contacts an edge of the second sub-electrode1142by covering the edge of the second sub-electrode1142. The third bank1153contacts an edge of the third sub-electrode1143by covering the edge of the third sub-electrode1143. As shown inFIG.5, the first sub-electrode1141is disposed on the upper surface of the planarization layer113, the second sub-electrode1142is disposed on the upper surface of the first bank1151, and the third sub-electrode1143is disposed on the upper surface of the second bank1152. Therefore, the first sub-electrode1141, the second sub-electrode1142and the third sub-electrode1143are provided in a stepwise structure in which their heights are gradually increased toward a right direction based onFIG.5.

Because the second sub-electrode1142is disposed higher than the first sub-electrode1141, the second sub-electrode1142can be electrically connected to the thin film transistor112through a first connection electrode CE1disposed on the planarization layer113in the second subpixel SP2. Further, the first connection electrode CE1provided in the second subpixel SP2can be disposed on the same layer as the first sub-electrode1141, for example, the upper surface of the planarization layer113, and be partially covered by the first bank1151. The other side of the first connection electrode CE1that is not covered by the first bank1151contacts the lower surface of the second sub-electrode1142. One side of the first connection electrode CE1can be connected to the source electrode112cor the drain electrode112dof the thin film transistor112through a contact hole formed by passing through the planarization layer113and the protective layer111c.

Because the third sub-electrode1143is disposed higher than the second sub-electrode1142, the third sub-electrode1143can be electrically connected to the thin film transistor112through the first connection electrode CE1disposed on the planarization layer113in the third subpixel SP3and a second connection electrode CE2disposed on the first bank1151. The first connection electrode CE1provided in the third subpixel SP3can also be disposed on the same layer as the first sub-electrode1141, for example, the upper surface of the planarization layer113, and be partially covered by the first bank1151. The other side of the first connection electrode CE1, which is not covered by the first bank1151, also contacts the lower surface one side of the second connection electrode CE2of the second connection electrode CE2. One side of the first connection electrode CE1provided in the third subpixel SP3can also be connected to the source electrode112cor the drain electrode112dof the thin film transistor112through the contact hole formed by passing through the planarization layer113and the passivation layer111c.

In addition, the second connection electrode CE2can be disposed on the same layer as the second sub-electrode1142, for example, the upper surface of the first bank1151, and be partially covered by the third bank1153. The other side of the second connection electrode CE2, which is not covered by the second bank1152, contacts the lower surface of the third sub-electrode1143. Therefore, the third sub-electrode1143can be electrically connected to the first connection electrode CE1provided in the third subpixel SP3and the second connection electrode CE2, so that a driving signal and/or driving power applied from the thin film transistor112can be transferred thereto.

As a result, in the display apparatus100according to the embodiment inFIG.5, as the first color filter131, the second color filter132and the third color filter133are provided in a stepwise structure, the light path can be changed toward the front surface directed toward the second substrate190even on the side133bof the third color filter133adjacent to the light path changing layer150as well as the side132bof the second color filter132adjacent to the light path changing layer150. Accordingly, the light efficiency of each different color, for example, green light and blue light can be improved.

Next,FIG.6is a schematic cross-sectional view illustrating a display apparatus according to still another embodiment of the present disclosure. The display apparatus100inFIG.6is the same as the display apparatus ofFIG.2except that the lower surface of the color filter130disposed in each subpixel is flat. Therefore, the same reference numerals are given for the same elements, and elements different from those ofFIG.1are described.

In the display apparatus shown inFIG.1, because the color filter130is formed along the profile of the encapsulation layer118having the same thickness for each subpixel, the lower surface of the color filter130disposed in each subpixel is provided in the same shape as the profile of the encapsulation layer118.

On the other hand, for the display apparatus shown inFIG.6, the lower surface of each of the first color filter131, the second color filter132and the third color filter133is flat. That is, after the upper surface of each of the encapsulation layer118provided in the first subpixel SP1, the encapsulation layer118provided in the second subpixel SP2and the encapsulation layer118provided in the third subpixel SP3is patterned to be flat through a photo process using a mask and an etching process, the color filters of colors corresponding to the respective subpixels can be formed at the same thickness. Therefore, each of the lower surface of the first color filter131contacting the encapsulation layer118of the first subpixel SP1, the lower surface of the second color filter132contacting the encapsulation layer118of the second subpixel SP2, and the third color filter133contacting the encapsulation layer118of the third subpixel SP3can be provided to be flat.

As each of the lower surface of the first color filter131, the lower surface of the second color filter132and the lower surface of the third color filter133is flat, the encapsulation layer118overlapped with the bank115in each subpixel can be provided to be thinner than the encapsulation layer118not overlapped with the bank115. For example, in the first subpixel SP1, the encapsulation layer118can include a first area118aoverlapped with the bank115at a boundary portion between the second subpixels SP2, and a second area118bthat is not overlapped with the bank115. As shown inFIG.6, as the lower surface of the first color filter131is planarized, a thickness ET1of the first area118aof the encapsulation layer118can be thinner than a thickness ET2of the second area118b.

However, a thickness CFT1of the first color filter131overlapped with the first area118aof the encapsulation layer118in the second direction or thickness direction of the first substrate110may be equal to a thickness CFT2of the first color filter131overlapped with the second area118bin the second direction. Because the upper surface of the encapsulation layer118provided in the first subpixel SP1is flat, the thickness of the first color filter131formed on the encapsulation layer118can be uniformly provided in the first subpixel SP1. Therefore, in the display apparatus100inFIG.6, even though leakage light L3is generated on the bank115by a leakage current from the subpixel (first subpixel SP1) for emitting light to the subpixel (second subpixel SP2) for not emitting light, the color filter130overlapped with the bank is thick, whereby the leakage current L3can be shielded, and the amount of light emitted through the color filter130can be reduced.

For example, the leakage light L3can be generated at the portion of the taper TP of the bank115, and the organic layer116(or the first stack1161of the organic light emitting layer116) becomes thinner in the portion of the taper TP, so that yellow-green light of the second stack1163may be mainly emitted rather than blue light of the first stack1161. Because the intensity of the emitted light is not great due to a resistance caused by the thin thickness of the organic light emitting layer116, the yellow-green leakage light L3does not pass through the red thick color filter on the bank and as a result can be extinguished, or be weakly emitted although passing through the red color filter.

In another example, in the stack structure of the organic light emitting layer116, when the second stack1163includes a light emitting layer for emitting blue light, the blue leakage light L3cannot pass through the red color filter, and thus can be shielded. As a result, the lower surface of the color filter130disposed in each subpixel is provided to be flat, so that the color filter130overlapped with the bank115, that is, the color filter130overlapped with the non-light emission area, can be provided to be thicker than the color filter130overlapped with the non-light emission area of another embodiment.

Because the color filter provided to be thick in the non-light emission area can shield the leakage light L3of another color emitted from the non-light emission area, color purity of the subpixel for emitting light can be improved. Also, the color filter provided to be thick in the non-light emission area also reduces the amount of the leakage light L3of the same color, which is emitted from the non-light emission area, thereby preventing a color mixture with an adjacent subpixel from occurring.

Next,FIG.7is a schematic cross-sectional view illustrating another example of a display apparatus according to yet another embodiment of the present disclosure. Referring toFIG.7, the upper layer170has the same refractive index as that of the light path changing layer150. Having the same refractive index means the corresponding layers are formed of the same material or include the same refractive index if formed of different materials. For example, the upper layer170and the light path changing layer150can be formed of air to have the same refractive index. AlthoughFIG.7shows hatching to represent that the upper layer170and the light path changing layer150have the same refractive index, the hatching can be omitted when the upper layer170and the light path changing layer150are formed of air. As shown inFIG.7, as the upper layer170and the light path changing layer150are formed of air to have the same refractive index, the air contact an upper surface of each of the plurality of color filters and a protruded side of the color filter. In this instance, the light path can be changed even on the upper surface of the color filter as well as the protruded side of the color filter.

Because the upper layer170is made of air, an opposite substrate on the upper layer170, that is, the second substrate190, can be bonded to the first substrate110or encapsulation layer118by the adhesive layer180. Therefore, as shown inFIG.7, the adhesive layer180can be provided to surround the upper layer170made of air. In this instance, the adhesive layer180can be provided to surround the light path changing layer150.

In addition, the upper layer170can be provided to have a refractive index smaller or lower than that of the light path changing layer150. For example, the light path changing layer150can be formed of a material having a refractive index, which is smaller than that of the color filter130but is greater than 1, and the upper layer170can be formed of air. Even in this instance, because the light path can be changed on the boundary surface where the protruded side of the color filter130and the light path changing layer150are adjacent to each other, the front light efficiency can be improved. In addition, the light path can be changed even on the boundary surface between the upper surface of the color filter130and the upper layer170that is the air.

Although the upper layer170is made of one material in the above example, the upper layer170disposed on the color filter130may be made of partially different materials to further improve front light efficiency. For example, the material of the upper layer170disposed to overlap the boundary portion or bank115between the plurality of subpixels may be made of a material having a refractive index lower than that of the material of the upper layer170disposed to overlap a central portion of the subpixel, so that the light path can be changed toward a center portion of the subpixel in the materials constituting the upper layer170, thereby improving front light efficiency.

As a result, the light path changing layer150adjacent to the color filter130and/or the upper layer170can be provided to have a refractive index lower than that of the color filter130, so that the light path of the side light emitted toward the adjacent subpixel can be changed to improve front light efficiency. Also, as one or more of the plurality of color filters are provided to be further protruded toward the second substrate190, the light path of the side light can be changed to the front direction from the first substrate110to the second substrate190even on the boundary surface between the protruded side of the color filter and the light path changing layer150, thereby maximizing front light efficiency. In addition, as the plurality of color filters have a stepwise structure, the side light L1emitted from different subpixels can be converted into the front light L2, whereby light efficiency of different colors can be improved.

According to embodiments of the present disclosure, the following advantageous effects can be obtained. As the light path changing layer is provided on the side of one or more of the color filters respectively provided in the plurality of subpixels, the front light efficiency can be improved. Further, as the first electrodes respectively provided in the plurality of subpixels have their respective heights different from each other, the length of the organic light emitting layer provided between the subpixels is lengthened so that the leakage current can be reduced or blocked. In addition, as the bank covering the edge of the first electrode has a taper, the thickness of the organic light emitting layer overlapped with the taper becomes thinner, whereby the leakage current to the adjacent subpixel can be reduced or blocked.

Also, as the thickness of the color filter overlapped with the non-light emission area is equal to that of the color filter overlapped with the light emission area, transmittance of light due to the leakage current can be reduced or blocked, whereby color purity can be improved.