Patent Publication Number: US-2022231240-A1

Title: Transparent organic light emitting display apparatus and method of manufacturing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Application is a Divisional of U.S. patent application Ser. No. 16/573,045 filed on Sep. 17, 2019, which claims the priority benefit of the Korean Patent Application No. 10-2018-0131996 filed on Oct. 31, 2018 in the Republic of Korea, the entire contents of all these applications being hereby expressly incorporated by reference into the present application. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure relates to a transparent organic light emitting display apparatus and a method of manufacturing the same. 
     Discussion of the Related Art 
     A display apparatus is widely used as a display screen of a notebook computer, a tablet computer, a smartphone, a mobile display device, a mobile information device in addition to a display screen of a television or a monitor. 
     An organic light emitting display is a self light emitting display device, and can be fabricated at a lightweight and slim size as it does not need a separate light source unlike a liquid crystal display (LCD). Also, the organic light emitting display is favorable in view of power consumption due to low voltage driving and also is excellent for color realization, a response speed, a viewing angle, and a contrast ratio (CR), whereby the organic light emitting display has been studied as a display for the next generation. 
     In order to satisfy a user&#39;s various needs, a transparent organic light emitting display apparatus capable of transmitting external light has been explored. The transparent organic light emitting display apparatus includes a plurality of pixels, wherein the pixel includes an emission area configured to display an image by a light emission of an organic light emitting device, and a transmission area configured to pass external light therethrough. A transparency of the transparent organic light emitting display apparatus may be secured by the use of transmission area. 
     However, an emitting portion of the organic light emitting device is formed of an organic material layer, and the emitting portion has an inferior adhesion strength to other layers formed of inorganic films or metal films. Thus, in the interface between the emitting portion and the other layers of the organic light emitting device, a delamination of the emitting portion frequently occurs by a physical deformation such as an external shock or bending force, to thereby deteriorate durability of the organic light emitting device. 
     SUMMARY 
     The present disclosure has been made in view of the above problems and other limitations associated with the related art, and it is an object of the present disclosure to provide a transparent organic light emitting display apparatus with good delamination resistance to a specific layer comprising an emission layer (EL) by a physical deformation such as an external shock or bending force, which is capable of reducing defects which might occur during a manufacturing process, and improving productivity. 
     In addition to the objects of the present disclosure as mentioned above, additional objects of the present disclosure will be clearly understood by those skilled in the art from the following description of the present disclosure. 
     In accordance with an aspect of the present disclosure, the above and other objects can be accomplished by the provision of a transparent organic light emitting display apparatus comprising an emission area; a transmission area disposed adjacent to the emission area and configured to pass external light therethrough; and an undercut area formed in the transmission area, wherein the undercut area is formed by filling an encapsulation layer. 
     In accordance with another aspect of the present disclosure, there is provided a method of manufacturing a transparent organic light emitting display apparatus having an emission area, and a transmission area disposed adjacent to the emission area and configured to pass external light therethrough, comprising sequentially forming an interlayer dielectric and a first protection layer on a first substrate; patterning a planarization layer on the first protection layer; forming an organic light emitting device on the planarization layer; and forming an encapsulation layer and an encapsulation substrate on the organic light emitting device, wherein a step of exposing and etching at least some portions of the transmission area by photolithography is carried out after the step of patterning the planarization layer. 
     According to one or more embodiments of the present disclosure, the transparent organic light emitting display apparatus includes the undercut area included in the transmission area so that it is possible to provide the transparent organic light emitting display apparatus with good delamination resistance to a specific layer comprising an emission layer (EL) by a physical deformation such as an external shock or bending force. 
     In addition to the effects of the present disclosure as mentioned above, additional objects of the present disclosure will be clearly understood by those skilled in the art from the following description of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a plane view illustrating a transparent organic light emitting display apparatus according to one embodiment of the present disclosure; 
         FIG. 2  is a plane view illustrating a pixel (P) of  FIG. 1 ; 
         FIG. 3A  is a cross sectional view along line I-I′ of  FIG. 1 ; 
         FIG. 3B  is an expanded view illustrating “A” of  FIG. 3A ; 
         FIGS. 4A to 4C  are cross sectional views illustrating examples of a structure of an undercut area (UA) in a transparent organic light emitting display apparatus according to one embodiment of the present disclosure; 
         FIG. 5A  is a cross sectional view illustrating two emission areas and a transmission area between the emission areas in a transparent organic light emitting display apparatus according to one embodiment of the present disclosure; 
         FIGS. 5B to 5D  are plane views illustrating different examples of an undercut area (UA) in a transparent organic light emitting display apparatus according to one embodiment of the present disclosure; 
         FIG. 6  is a cross sectional view illustrating a case of bending a transparent organic light emitting display apparatus according to one embodiment of the present disclosure; and 
         FIGS. 7A to 7G  are cross sectional views illustrating a method of manufacturing a transparent organic light emitting display apparatus according to one embodiment of the present disclosure, which correspond to cross sectional views along I-I′ of  FIG. 3A . 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Advantages and features of the present disclosure, and implementation methods thereof will be clarified through following embodiments described with reference to the accompanying drawings. The present disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Further, the present disclosure is only defined by scopes of claims. 
     A shape, a size, a ratio, an angle, and a number disclosed in the drawings for describing embodiments of the present disclosure are merely an example, and thus, the present disclosure is not limited to the illustrated details. Like reference numerals refer to like elements throughout the specification. In the following description, when the detailed description of the relevant known function or configuration is determined to unnecessarily obscure the important point of the present disclosure, the detailed description will be omitted. 
     In a case where ‘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 the position relationship is described as ‘upon-’, ‘above˜’, ‘below-’, and ‘next to-’, one or more portions can be arranged between two other portions unless ‘just’ or ‘direct’ is used. 
     In describing a time 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. 
     It will be understood that, although the terms “first”, “second”, etc. can 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. 
     It should be understood that the term “at least one” includes all combinations related with any one item. For example, “at least one among a first element, a second element and a third element” can include all combinations of two or more elements selected from the first, second and third elements as well as each element of the first, second and third elements. 
     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 carried out independently from each other, or can be carried out together in co-dependent relationship. 
     Hereinafter, a transparent organic light emitting display apparatus and a method of manufacturing the same will be described in detail with reference to the accompanying drawings. In the drawings, the same or similar elements are denoted by the same reference numerals even though they are depicted in different drawings. 
       FIG. 1  is a plane view illustrating a transparent organic light emitting display apparatus according to one embodiment of the present disclosure. All the components of the transparent organic light emitting display apparatus according to all embodiments of the present disclosure are operatively coupled and configured. 
     Referring to  FIG. 1 , a transparent organic light emitting display apparatus  100  includes a substrate  110 , a pixel array  1900 , a display driving circuit portion  210 , and a scan driving circuit portion  220 . 
     The substrate  110  is a base substrate, which can be a flexible substrate. For example, the substrate  110  can include a transparent polyimide material. As the polyimide-based substrate  110  is manufactured at a high-temperature deposition process, good thermal resistance polyimide, which endures a high temperature, can be used for the substrate  110 . The polyimide-based substrate  110  can be formed by curing polyimide resin coated at a constant thickness on a front surface of a sacrificial layer prepared in a carrier glass substrate. Herein, the carrier glass substrate can be separated from the substrate  110  by a release of the sacrificial layer for a laser release process. And, the sacrificial layer can be formed of amorphous silicon (a-Si) or silicon nitride (SiN). 
     According to one embodiment of the present disclosure, the substrate  110  can be a glass substrate. For example, the substrate  110  can include a main component of silicon oxide (SiO 2 ) or aluminum oxide (Al 2 O 3 ). 
     The substrate  110  can include a display area (AA), a non-display area (NA), and a pad area (PA). The display area (AA) is an area for displaying an image thereon, which can be defined as a central area of the substrate  110 . Herein, the display area (AA) can correspond to an active area of the pixel array  1900 . For example, the display area (AA) can include a plurality of pixels P formed in every pixel area defined by crossing a plurality of gate lines and a plurality of data lines. Herein, each of the plurality of pixels can be defined as a minimum unit configured to emit light. 
     The non-display area (NA) is an area on which an image is not displayed. The non-display area (NA) and the pad area (PA) can surround the display area (AA). For example, the non-display area (NA) can be defined in the periphery area of the substrate  110  while being configured to surround the display area (AA). 
     The pad area (PA) can be disposed in one peripheral area of the substrate  110 , and a pad electrode of the pad area (PA) can be electrically connected with a flexible circuit film  211  of the display driving circuit portion  210 . Accordingly, the transparent organic light emitting display apparatus  100  can receive signal and power from the display driving circuit portion  210  through the pad electrode. 
     The pixel array  1900  can include a thin film transistor layer and/or an emission device layer. The thin film transistor layer can include a thin film transistor, a gate insulating film, an interlayer dielectric, a protection film, and a planarization layer. And, the emission device layer can include a plurality of organic light emitting devices (e.g., organic light emitting diodes) and a plurality of banks. A detailed structure of the pixel array  1900  will be described later with reference to  FIG. 2 . 
     The display driving circuit portion  210  is connected with a pad portion (or pad electrode) prepared in the pad area (PA) of the substrate  110 , whereby an image corresponding to video data supplied from a display driving system can be displayed on each pixel. According to one embodiment of the present disclosure, the display driving circuit portion  210  can include a plurality of flexible circuit films  211 , a plurality of data driving integrated circuits  213 , a printed circuit board  215 , and a timing controller  217 . 
     An input terminal prepared in one side in each of the plurality of flexible circuit films  211  is attached to the printed circuit board  215  by a film attachment process, and an output terminal prepared in the other side in each of the plurality of flexible circuit films  211  can be attached to the pad portion (or pad electrode) by the film attachment process. According to one embodiment of the present disclosure, each of the plurality of flexible circuit films  211  can be flexible and bent so as to reduce a bezel area of the transparent organic light emitting display apparatus  100 . For example, the plurality of flexible circuit films  211  can be formed of tape carrier package (TCP) or chip on flexible board (COF, or chip on film). 
     Each of the plurality of data driving integrated circuits  213  can be individually mounted on each of the plurality of flexible circuit films  211 . The plurality of data driving integrated circuits  213  can receive pixel data and data control signal from the timing controller  217 , can convert the pixel data into an analog data signal for each pixel in accordance with the data control signal, and can supply the analog data signal for each pixel to the corresponding data line. 
     The printed circuit board  215  can support the timing controller  217 , and can transmit the signal and power between elements of the display driving circuit portion  210 . The printed circuit board  215  can provide signals and driving power, supplied from the timing controller  217  so as to display an image in each pixel, to the plurality of data driving integrated circuits  213  and the scan driving circuit portion  220 . To this end, various signal lines and power source lines can be prepared on the printed circuit board  215 . For example, one or more printed circuit boards  215  can be provided on the basis of the number of flexible circuit films  211 . 
     The timing controller  217  is mounted on the printed circuit board  215 , and can receive the video data and timing synchronized signal provided from the display driving system through a user connector prepared in the printed circuit board  215 . The timing controller  217  can generate pixel data by aligning the video data to be appropriate for a pixel arrangement structure on the basis of the timing synchronized signal, and can provide the generated pixel data to the corresponding data driving integrated circuit  213 . And, the timing controller  217  can generate each of the data control signal and scan control signal based on the timing synchronized signal, can control a driving timing in each of the plurality of data driving integrated circuits  213  through the data control signal, and can control a driving timing of the scan driving circuit portion  220  through the scan control signal. Herein, the scan control signal can be supplied to the corresponding scan driving circuit portion  220  through the non-display area (NA) of the substrate  110  and the first and/or last flexible circuit film among the plurality of flexible circuit films  211 . 
     The scan driving circuit portion  220  can be prepared in the non-display area (NA) of the substrate  110 . The scan driving circuit portion  220  can generate a scan signal in accordance with the scan control signal provided from the display driving circuit portion  210 , and can supply the scan signal to the corresponding scan line in accordance with a preset order. According to one embodiment of the present disclosure, the scan driving circuit portion  220  together with the thin film transistor can be formed in the non-display area (NA) of the substrate  110 . 
       FIG. 2  is a plane view illustrating an example of the pixel (P) of  FIG. 1 . 
     Referring to  FIG. 2 , each pixel (P) of the transparent organic light emitting display apparatus according to one embodiment of the present disclosure can include a transmission area (TA) and an emission area (EA), or can include one or more TAs and one or more EAs. The transmission area (TA) corresponds to the area through which incident light passes intactly, and the emission area (EA) corresponds to the area configured to emit light. Thus, in case of the transparent organic light emitting display apparatus according to one embodiment of the present disclosure, an object or background positioned in its rear surface can be seen through the use of transmission areas (TA), and an image can be displayed through the use of emission areas (EA). 
     As shown in  FIG. 2 , multiple pixels (P) can also be provided in the emission area (EA). Each of the pixels (P) can include a red emitting portion (R), a green emitting portion (G), a blue emitting portion (G), and a white emitting portion (W), but the white emitting portion (W) can be omitted. Also, each of the pixels (P)can include at least two among a red emitting portion (R), a green emitting portion (G), a blue emitting portion (G), a yellow emitting portion, a magenta emitting portion, and a cyan emitting portion. 
     Accordingly, if the transparent organic light emitting display apparatus  100  is not driven, a user can watch the background, e.g., objects behind the rear of the display, through the transmission area (TA). If the transparent organic light emitting display apparatus  100  is driven, a user can watch both the displayed image through the emission area (EA) and the background through the transmission area (TA). In  FIG. 2 , a size ratio of the emission area (EA) to the transmission area (TA) is about 1:1, but is not limited to this ratio. A size ratio of the emission area (EA) to the transmission area (TA) can be preset in various types. According to one embodiment of the present disclosure, the transmission area (TA) can occupy 50% or more than 50% of one pixel in the transparent organic light emitting display apparatus. 
       FIG. 3A  is a cross sectional view along line I-I′ of  FIG. 1 , and  FIG. 3B  is an expanded view illustrating “A” of  FIG. 3A . 
     Referring to  FIGS. 3A and 3B , the transparent organic light emitting display apparatus can include a first substrate (base substrate)  110 , a light shielding layer (LS), a thin film transistor (T), a gate insulating film  130 , an interlayer dielectric  140 , a first protection layer  150 , a planarization layer  160 , an organic light emitting device (E), a bank (B), a second protection layer  170 , an encapsulation layer  180 , first and second auxiliary power lines (EVSS 1 , EVSS 2 ), a line contact pattern (LCP), a contact pad (CP), a storage capacitor (Cst), a signal pad (SP), a pad auxiliary electrode (PAE), a pad electrode (PE), a color filter  191 , a black matrix  193 , a second substrate  190 , and a dam  300 . 
     The first substrate  110  is the base substrate, which can be a transparent flexible substrate capable of being bent, or a glass substrate. According to one embodiment of the present disclosure, the first substrate  110  can include a transparent polyimide material, but is not limited to this material. The first substrate  110  can be formed of a transparent plastic material such as polyethylene terephthalate. According to one embodiment of the present disclosure, the first substrate  110  can include a main component of silicon oxide (SiO 2 ) or aluminum oxide (Al 2 O 3 ). 
     The light shielding layer (LS) can be disposed on the substrate  110  while being overlapped with the thin film transistor (T). For example, the light shielding layer (LS) can be obtained by depositing metal on the substrate  110  and carrying out an exposure patterning process to the metal deposited on the substrate  110 . 
     The buffer layer  120  can be disposed on the substrate  110  and the light shielding layer (LS). According to one embodiment of the present disclosure, the buffer layer  120  can be formed by depositing a plurality of inorganic films. For example, the buffer layer  120  can be formed in a multi-layered structure obtained by depositing at least one of inorganic films, for example, silicon oxide film (SiOx), silicon nitride film (SiN), and silicon oxide nitride film (SiON). In order to prevent moisture from being permeated into the organic light emission device (E) through the substrate  110 , the buffer layer  120  can be formed on an entire upper surface of the substrate  110 . 
     The thin film transistor (T) can be disposed in each of the plurality of pixel areas on the buffer layer  120 . According to one embodiment of the present disclosure, the thin film transistor (T) can include an active layer (ACT), a gate electrode (GE), a source electrode (SE), and a drain electrode (DE). 
     The active layer (ACT) can be prepared in the pixel area of the substrate  110 . The active layer (ACT) can be overlapped with the gate electrode (GE), the source electrode (SE), and the drain electrode (DE), and the active layer (ACT) can include a channel region and source/drain regions, wherein the channel region can be formed in a central area of the active layer (ACT), and the source/drain regions can be disposed while being parallel to each other under the circumstances that the channel region is disposed in-between. Also, the gate insulating film  130  can be prepared on the active layer (ACT). In detail, the gate insulating film  130  can be disposed on the channel region of the active layer (ACT), and can be configured to insulate the active layer (ACT) and the gate electrode (GE) from each other, and the gate electrode (GE) can be prepared on the gate insulating film  130 . 
     The interlayer dielectric  140  can be prepared on the gate electrode (GE). The interlayer dielectric  140  can protect the thin film transistor (T). In the interlayer dielectric  140 , a corresponding partial portion configured to bring the active layer (ACT) into contact with the source electrode (SE) or drain electrode (DE) can be removed. For example, the interlayer dielectric  140  can include a first contact hole through which the source electrode (SE) penetrates, and a second contact hole through which the drain electrode (DE) penetrates. Also, the interlayer dielectric  140  can be formed on the buffer layer  120  of the transmission area (TA). According to one embodiment of the present disclosure, the interlayer dielectric  140  can include a silicon oxide film (SiO 2 ) or a silicon nitride film (SiN), or the interlayer dielectric  140  can be formed in a multi-layered structure comprising a silicon oxide film (SiO 2 ) and a silicon nitride film (SiN). 
     The first protection layer  150  can be prepared on the interlayer dielectric  140 , the source electrode (SE), and the drain electrode (DE). The first protection layer  150  can protect the source electrode (SE) and the drain electrode (DE). The first protection layer  150  can include a third contact hole through which an anode electrode (AE) penetrates. Herein, the third contact hole of the first protection layer  150  can be connected with a fourth contact hole of the planarization layer  160 , wherein the anode electrode (AE) penetrates through the fourth contact hole. Also, according to one embodiment of the present disclosure, the first protection layer  150  can include a silicon oxide film (SiO 2 ) or a silicon nitride film (SiN). 
     The planarization layer  160  is disposed on the substrate  110 , and can be configured to cover the thin film transistor (T) disposed in each of the plurality of pixel areas. In detail, the planarization layer  160  is prepared on the thin film transistor (T), and can be configured to planarize an upper end of the thin film transistor (T). According to one embodiment of the present disclosure, the anode electrode (AE) and the contact pad (CP) can be prepared while being apart from each other in the upper end of the planarization layer  160 . For example, the planarization layer  160  can include the fourth contact hole through which the anode electrode (AE) penetrates. Herein, the fourth contact hole of the planarization layer  160  can be connected with the third contact hole of the first protection layer  150 , whereby the anode electrode (AE) penetrates therethrough. For example, the planarization layer  160  can include resin such as photo acryl and polyimide. 
     The transparent organic light emitting display apparatus  100  according to one embodiment of the present disclosure can include the emission area (EA), the transmission area (TA) which is disposed adjacent to the emission area (EA) and is configured to pass external light therethrough, and an undercut area (UA— FIG. 3B ) formed in the transmission area (TA). The undercut area (UA) can be formed by filling the encapsulation layer  180 , and can be defined by an overhanging portion of the planarization layer  160 . The undercut area (UA) can be formed by etching all the first protection layer  150  and etching at least some of the interlayer dielectric  140  in “A” of  FIG. 3A , whereby the undercut area (UA) can be defined as the area filled with the encapsulation layer  180 . 
     Referring to  FIGS. 3A and 3B , in one embodiment of the present disclosure, the undercut area (UA) can be formed by selectively etching the first protection layer  150  and the interlayer dielectric  140  of the transmission area (TA). According to one embodiment of the present disclosure, this selective etching can be carried out by a photolithography process of exposing a predetermined area including the undercut area (UA), and a following process of etching the first protection layer  150  and the interlayer dielectric  140  for the predetermined area including the undercut area (UA) exposed by the photolithography process. 
     The predetermined area including the undercut area (UA) exposed by photolithography can further include the planarization layer  160  which is overlapped with at least some of the undercut area (UA), and the planarization layer  160  can be formed in an upper portion of the undercut area (UA). Accordingly, the planarization layer  160  can include a predetermined protruding portion, and this protruding portion can be formed in the upper portion of the undercut area (UA). Also, this protruding portion is surrounded by a cathode electrode (CE) and the second protection layer  170  formed by the following process, and this protruding portion is combined with the undercut area (UA) after the process of filling the encapsulation layer  180 , whereby it is possible to form a cross section of a hook structure capable of preventing the separation. 
     According to one embodiment of the present disclosure, a selective wet etching process can be carried out by the use of wet etchant capable of selectively etching only the interlayer dielectric  140  and the first protection layer  150  without etching the planarization layer  160 . As described above, the planarization layer  160  include resin such as photo acryl and polyimide, and the interlayer dielectric  140  and the first protection layer  150  can be formed of a plurality of inorganic films including a silicon oxide film (SiO 2 ) or a silicon nitride film (SiN). According to one embodiment of the present disclosure, the interlayer dielectric  140  and the first protection layer  150  can be formed of a plurality of layers comprising a silicon oxide film (SiO 2 ). 
     Accordingly, the photolithography process is carried so as to expose only the predetermined area including the undercut area (UA). If the planarization layer is formed while being overlapped with at least some of the undercut area, for the following etching process, the overlapped planarization layer  160  is not etched, and the interlayer dielectric  140  and the first protection layer  150  disposed below the planarization layer  160  are etched so that it is possible to form the undercut area (UA). A sidewall of the interlayer dielectric  140  and the first protection layer  150  in the undercut area (UA) can have a predetermined taper angle (θ) above 90°. 
     In  FIGS. 3A and 3B , the same taper angle (θ) is shown by the etching of the interlayer dielectric  140  and the first protection layer  150  in the undercut area (UA). However, if the interlayer dielectric  140  and the first protection layer  150  are formed of the different materials, or are deposited to have the different properties such as hardness, it is possible to form an etching profile with a step difference caused by the different taper angles and the different etching levels in accordance with the different etching speeds. This will be described later in detail with reference to  FIGS. 4A to 4C . 
     The organic light emitting device (E) is disposed on the planarization layer  160  in the plurality of pixel areas, and can be electrically connected with the thin film transistor (T). The organic light emitting device (E) can include the anode electrode (AE), an emission layer (EL), and the cathode electrode (CE). 
     The anode electrode (AE) is prepared on the planarization layer  160  in the plurality of pixel areas, and can be electrically connected with the source electrode (SE) of the thin film transistor (T). The anode electrode (AE) can be in contact with the source electrode (SE) of the thin film transistor (T) through the fourth contact hole prepared in the planarization layer  160 . The anode electrode (AE) can include a first anode electrode, a second anode electrode, and a third anode electrode. 
     The emission layer (EL) can be prepared on the anode electrode (AE) and the contact pad (CP). The emission layer (EL) can be formed for the entire pixel areas in common, however, the emission layer (EL) is not divided into each of the pixel areas. For example, the emission layer (EL) can include a hole transporting layer, an organic light emitting layer, and an electron transporting layer. According to one embodiment of the present disclosure, the emission layer (EL) can further include at least one functional layer so as to improve a light emission efficiency of the emission layer (EL) and to increase a lifespan of the emission layer (EL). And, the emission layer (EL) disposed on the contact pad (CP) can be removed for a cathode contact between the contact pad (CP) and the cathode electrode (CE). 
     The emission layer (EL) can be manufactured by a vacuum deposition process. In one embodiment of the present disclosure, if there is the structure of undercut area (UA) overlapped with at least some of the planarization layer  160 , the emission layer (EL) has an inferior step coverage by the deposition process of the emission layer (EL). Thus, the emission layer (EL) can be not deposited in some portions of the undercut area (UA) overlapped with the planarization layer  160 . 
     The cathode electrode (CE) can be prepared on the emission layer (EL). The cathode electrode (CE) can be formed as a common electrode type for all the pixel areas without being divided into each of the pixel areas. According to one embodiment of the present disclosure, the cathode electrode (CE) can be formed of transparent conductive oxide (TCO) such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO). 
     The cathode electrode (CE) has a superior step coverage by the deposition process. Thus, when the cathode electrode (CE) is deposited in the undercut area (UA), at least some of the cathode electrode (CE) can be deposited in some portions of the undercut area (UA) overlapped with the planarization layer  160 , and can be deposited in a lower end portion of the planarization layer  160  overlapped with the undercut area (UA). 
     The bank (B) is disposed on the planarization layer  160  while being configured to divide the plurality of anode electrodes (AE) and the plurality of contact pads (CP). In detail, the bank (B) can electrically insulate the anode electrode (AE) from the contact pad (CP). The bank (B) can cover some of an upper portion of the contact pad (CP), and lateral surfaces and the remaining of the upper portion of the contact pad (CP) which are not covered by the bank (B) can be exposed to a cathode contact area. 
     And, the bank (B) can cover some portions of the anode electrode (AE). Thus, the bank (B) is disposed between the plurality of anode electrodes (AE) and the contact pad (CP), to thereby electrically insulate the contact pad (CP) from the adjacent anode electrodes (AE). 
     The second protection layer  170  can cover the display area (AA). In detail, the second protection layer  170  can be disposed on the organic light emitting device (E) of the emission area (EA). 
     According to one embodiment of the present disclosure, the second protection layer  170  can be coated onto the entire surface of the organic light emitting device (E), the contact pad (CP), and the first protection layer  150  by the deposition process. Herein, the second protection layer  170  can be formed by coating various materials by the deposition process, and can be stably deposited without regard to the material of each of the organic light emitting device (E), the contact pad (CP), and the first protection layer  150 . According to one embodiment of the present disclosure, the second protection layer  170  can be formed in a multi-layered structure obtained by depositing one or more silicon oxide nitride films (SiON). 
     According to one embodiment of the present disclosure, the second protection layer  170  can be manufactured by a chemical vapor deposition (CVD) method. The second protection layer  170  has superior step coverage by the CVD method, whereby at least some of the second protection layer  170  can be deposited in the area of the undercut area (UA) overlapped with the planarization layer  160 . However, the deposition method of the second protection layer  170  is not limited to the chemical vapor deposition (CVD) method. Any method having superior step coverage can be applied to the deposition method of the second protection layer  170 . 
     The encapsulation layer  180  can cover the second protection layer  170  on the display area (AA). The encapsulation layer  180  prevents a permeation of external moisture, to thereby prevent the emission layer (EL) from being deteriorated. According to one embodiment of the present disclosure, the encapsulation layer  180  can be formed of at least one inorganic film and at least one organic film. The encapsulation layer  180  can be cured by a thermo-curing method or ultraviolet-curing method. 
     The encapsulation layer  180  can cover the entire surface of the second protection layer  170  on the display area (AA) and fills the undercut area UA. For example, the encapsulation layer  180  can be formed of a silicon oxide film (SiO 2 ), a silicon nitride film (SiN) or a silicon oxide nitride film (SiON), or can be formed in a multi-layered structure of inorganic films such as a silicon oxide film (SiO 2 ), a silicon nitride film (SiN) and a silicon oxide nitride film (SiON). As the encapsulation layer  180  covers the organic light emitting device (E) of the display area (AA), it is possible to prevent moisture or oxygen from being permeated into the organic light emitting device (E). 
     The undercut area (UA) can be filled with the encapsulation layer  180 . In detail, the undercut area (UA), which is not fully filled with the aforementioned emission layer (EL), the cathode electrode (CE), and the second protection layer  170 , can be filled with the encapsulation layer  180 . 
     Referring to  FIG. 3B , the encapsulation layer  180  filled in the undercut area (UA) has the cross sectional structure of a hook shape, whereby it is possible to provide the transparent organic light emitting display apparatus with the good delamination resistance to a specific layer comprising the emission layer (EL) by a physical deformation such as an external shock and bending force. 
     In the transparent organic light emitting display apparatus  100  according to one embodiment of the present disclosure, the encapsulation layer  180  filled in the undercut area (UA) has the cross sectional structure of the hook shape. Thus, if the physical deformation occurs in the display apparatus  100  by the external shock or bending force, the delamination is not generated by adhesion strength in the interface between the encapsulation layer  180  and the second protection layer  170  disposed below the encapsulation layer  180  or between the encapsulation layer  180  and the second substrate  190  disposed above the encapsulation layer  180 . However, only when a force capable of separating the encapsulation layer  180  having the hook structure filled in the undercut area (UA) from the undercut area (UA) is applied, the delamination may occur. Thus, the transparent organic light emitting display apparatus includes the encapsulation layer  180  filled in the undercut area (UA) and configured to have a structure preventing or minimizing a separation by the physical deformation due to, e.g., external shock and bending force, to thereby realize the good bending durability. 
     Also, the undercut area (UA) can be provided at the position being adjacent to the emission area (EA), and can be disposed at both sides of the emission area (EA). Thus, the encapsulation layer  180  having the hook structure filled in the undercut area (UA) can function as one kind of protection layer improving the resistance to the physical deformation associated with external shock and bending force to be applied to the organic light emitting device (E) comprising the emission layer (EL) which is vulnerable to the delamination. 
     A second auxiliary power line (EVSS 2 ) is electrically connected with a line contact pattern (LCP), is disposed in the same layer as that of the gate electrode (GE), and is formed of the same material as that of the gate electrode (GE). In detail, the second auxiliary power line (EVSS 2 ) can be disposed on the gate insulating film  130 . 
     A first auxiliary power line (EVSS 1 ) is electrically connected with the line contact pattern (LCP), is disposed in the same layer as that of the light shielding layer (LS), and is formed of the same material as that of the light shielding layer (LS). In detail, the first auxiliary power line (EVSS 1 ) can be disposed on the substrate  110 . 
     The line contact pattern (LCP) can be disposed on the interlayer dielectric  140  while being apart from the source electrode (SE) and the drain electrode (DE). And, the line contact pattern (LCP) can be electrically connected with the contact pad (CP) through the contact hole prepared in the planarization layer  160 . The line contact pattern (LCP) can include a lower line contact pattern and an upper line contact pattern. 
     The contact pad (CP) can be disposed on the planarization layer  160  in the plurality of pixel areas, and can be electrically connected with the line contact pattern (LCP). The contact pad (CP) can be electrically connected with the line contact pattern (LCP) through the contact hole prepared in the planarization layer  160  and the first protection layer  150 . The contact pad (CP) can include a first metal film, a second metal film, and a third metal film. 
     The signal pad (SP) can be formed on the buffer layer  120 . For example, the signal pad (SP) can be formed of the same material as that of the gate electrode (GE), and can be disposed in the same layer as that of the gate electrode (GE). 
     The pad auxiliary electrode (PAE) can be prepared on the interlayer dielectric  140 . For example, the pad auxiliary electrode (PAE) can be in contact with the signal pad (SP) through the contact hole prepared in the interlayer dielectric  140 , and can be in contact with the pad electrode (PE) through the contact hole prepared in the first protection layer  150 . The pad auxiliary electrode (PAE) can include a lower pad auxiliary electrode and an upper pad auxiliary electrode. 
     The pad electrode (PE) can be formed on the first protection layer  150 . For example, the pad electrode (PE) can be in contact with the pad auxiliary electrode (PAE) through the contact hole prepared in the first protection layer  150 . The pad electrode (PE) can include a first pad electrode, a second pad electrode, and a third pad electrode. 
     The storage capacitor (Cst) can include a lower capacitor electrode (BC), a middle capacitor electrode (MC), and an upper capacitor electrode (TC). 
     The second substrate  190  can be formed on the upper surface of the encapsulation layer  180 . The second substrate  190  can be an encapsulation substrate. The second substrate  190  can include a plastic film, a glass substrate, or an encapsulation film. On the lower surface of the second substrate  190 , there are a color filter layer  191  and a black matrix  193 . The black matrix  193  can be patterned to define the pixel area. The color filter layer  191  can be formed in the pixel area defined by the black matrix  193 . The color filter layer  191  can include a red (R) color filter, a green (G) color filter, and a blue (B) color filter patterned by each pixel. 
     The dam  300  is formed between the first substrate  110  and the second substrate  190  while being disposed in the periphery of the display area (AA), wherein the dam  300  can be provided to enhance adhesion strength between the second substrate  190  and the encapsulation layer  180 , and to prevent a moisture permeation. The dam  300  can be formed in the boundary area between the display area (AA) and the pad area (PA). The dam  300  can include sealant, and moisture-absorbing filler dispersed in the sealant. The sealant can be thermo-curing sealant or photo-curing sealant. 
       FIGS. 4A to 4C  are cross sectional views illustrating examples of the structure of the undercut area (UA) in the transparent organic light emitting display apparatus according to one embodiment of the present disclosure. 
     Referring to an example of  FIG. 4A , the selective etching profile of the interlayer dielectric  140  and the first protection layer  150  in the undercut area (UA) has the step coverage with the step shape. According to one embodiment of the present disclosure, the selective etching profile having the above shape can be generated when an etching rate of the first protection layer  150  to a wet etchant used for the wet etching process is higher than an etching rate of the interlayer dielectric  140 . Accordingly, a width (W 1 ) by the etching of the first protection layer  150  in the undercut area (UA) can be larger than a width (W 2 ) by the etching of the interlayer dielectric  140  in the undercut area (UA). 
     If the selective etching profile of the interlayer dielectric  140  and the first protection layer  150  has the step shape in the undercut area (UA), the etched width (W 1 ) of the first protection layer  150  in the undercut area (UA) is larger than the etched width (W 2 ) of the interlayer dielectric  140  in the undercut area (UA), whereby the encapsulation layer  180  filled in the undercut area (UA) extends more toward the planarization layer  160 . 
     In this case, the etched width (W 1 ) of the first protection layer  150  in the undercut area (UA), and the etched width (W 2 ) of the interlayer dielectric  140  in the undercut area (UA) can be defined as the etch width measured in the middle of the etch depth. 
     Referring to another example of  FIG. 4B , the first protection layer  150  in the undercut area (UA) is etched in the taper angle (inclined angle) θ 1 , and the interlayer dielectric  140  in the undercut area (UA) is etched in the taper angle θ 2 . For example, both angles θ 1  and θ 2  may be greater than 90 degrees. According to one embodiment of the present disclosure, the selective etching profile having the above shape can be generated when the interlayer dielectric  140  and the first protection layer  150  are formed of the same material and are manufactured under the same process conditions. For example, if the interlayer dielectric  140  and the first protection layer  150  are formed of silicon oxide films (SiO 2 ), and a process temperature of the first protection layer  150  is relatively lower than a process temperature of the interlayer dielectric  140 , the first protection layer  150  and the interlayer dielectric  140  can have the different properties. Accordingly, an etching rate of the first protection layer  150  can be relatively higher than an etching rate of the interlayer dielectric  140 . Also, if the interlayer dielectric  140  and the first protection layer  150  are formed of the same material, the step difference may be not generated in the interface between the interlayer dielectric  140  and the first protection layer  150 , but is not limited to this structure. The predetermined step difference can be generated in the interface between the interlayer dielectric  140  and the first protection layer  150 . 
     As described in  FIGS. 4A and 4B , if the step different is generated by the relatively-large etched width (W 1 ) of the interlayer dielectric  140  in the undercut area (UA) in comparison to the etched width (W 2 ) of the first protection layer  150  in the undercut area (UA), or the etching taper angle (θ 1 ) of the first protection layer  150  in the undercut area (UA) is larger than the etching taper angle (θ 2 ) of the interlayer dielectric  140  in the undercut area (UA), the undercut area (UA) overlapped with the planarization layer  160  extends more toward the planarization layer  160  or the emission area (EA), whereby the encapsulation layer  180  having the hook shape filled in the undercut area (UA) can have a structure that can minimize or prevent separation from the undercut area (UA). 
     Referring to another example of  FIG. 4C , the cathode electrode (CE) and the second protection layer  170  are formed on the sidewall of the area overlapped with the planarization layer of the undercut area (UA). 
     Referring to  FIG. 4C  in connection with  FIG. 3B , the case of  FIG. 3B  shows that the cathode electrode (CE) and the second protection layer  170  are not deposited in the undercut area (UA) overlapped with the planarization layer  160 . For example, in  FIG. 4C , the cathode electrode (CE) and the second protection layer  170  cover the entire sidewalls of the UA directly under the planarization layer  160 . As a result, the sidewalls and the bottom surface of the UA may be covered by the CE and the second protection layer  170 . The difference of deposition profile between  FIG. 4C  and  FIG. 3B  can be generated by the change of deposition process conditions such as the process pressure or source supply amount. According to one embodiment of the present disclosure, the structure of  FIG. 4C  can have the superior step coverage by carrying out the deposition process of the cathode electrode (CE) and the second protection layer  170  under the preset process conditions of the relatively low pressure and relatively low source supply amount. The structure of  FIG. 3B  can be obtained by carrying out the deposition process of the cathode electrode (CE) and the second protection layer  170  under the preset process conditions of the relatively higher pressure and relatively higher source supply amount in comparison to the process conditions of  FIG. 4C . 
     Also, the profile of the lateral surface portion and the lower end portion in which the interlayer dielectric  140  and the first protection layer  150  of the undercut area (UA) are etched is formed in a linear shape, but is not limited to this shape. The profile of the lateral surface portion and the lower end portion in which the interlayer dielectric  140  and the first protection layer  150  of the undercut area (UA) are etched can be formed in a predetermined streamlined shape. 
       FIG. 5A  is a cross sectional view illustrating an example of two emission areas and a transmission area between the two emission areas in the transparent organic light emitting display apparatus according to one embodiment of the present disclosure, and  FIGS. 5B to 5D  are plane views illustrating various example of the undercut area (UA) of the transparent organic light emitting display apparatus according to one embodiment of the present disclosure. The same or similar elements of  FIG. 3A  are shown and used in  FIG. 5A . 
     Referring to  FIG. 5A , one or more undercut areas (UA) can be formed in the transmission area (TA) of the transparent organic light emitting display apparatus according to one embodiment of the present disclosure, and the encapsulation layer  180  of the hook shape can be formed in the undercut area(s) (UA). Thus, even though the external shock is applied, or the physical deformation such as the bending force is generated, it is possible to realize the improved stable structure of the transparent organic light emitting display apparatus  100  without the delamination of the specific layer comprising the emission layer (EL). 
       FIGS. 5B to 5D  are plane views illustrating various examples of the undercut area (UA) of the transparent organic light emitting display apparatus according to one embodiment of the present disclosure. 
     Referring to a first example of  FIG. 5B , the undercut area (UA) can be configured to have a closed-loop structure in the transmission area (TA). According to one embodiment of the present disclosure, the undercut area (UA) has the closed-loop structure, and the undercut area (UA) can be overlapped with or correspond to unit pixel. In  FIG. 5B , the undercut area (UA) is formed in each of all the unit pixels, but not necessarily. The undercut area (UA) can be provided in accordance with requirements for the bending properties of the transparent organic light emitting display apparatus  100 . For example, the undercut area (UA) can be formed only in 50% of all the pixels. 
     Referring to  FIG. 5D , the undercut area (UA) can have the closed-loop structure in the transmission area (TA), and can be overlapped with the plurality of pixels. In  FIG. 5D , the undercut area (UA) of the closed-loop structure can be formed in the transmission area (TA) corresponding to the two pixels, but is not limited to this structure. The size of the undercut area (UA) can vary in accordance with requirements for the bending properties of the transparent organic light emitting display apparatus  100 . 
     Referring to  FIG. 5C , the undercut area (UA) is not limited to the closed-loop structure in the transmission area (TA), and the undercut area (UA) can be formed as at least one line pattern in the transmission area (TA). For example, the undercut area (UA) can be selectively formed only in the left and right sides of the transmission area (TA) being adjacent to the emission area (EA), e.g., in the shape of two separate lines. 
     As described in  FIGS. 5A to 5D , the undercut area (UA) (e.g., in the closed-loop structure or line patterns) can disposed in the left and right sides of the emission area (EA), whereby the encapsulation layer  180  (e.g., having the hook structure) filled in the undercut area (UA) can be provided to surround the both sides of the emission area (EA). Accordingly, the encapsulation layer  180  (e.g., having the hook structure) filled in the undercut area (UA) can function as one kind of protection layer capable of improving the resistance to the physical deformation such as the external shock or bending force to be applied to the organic light emitting device (E) comprising the emission layer (EL) which is vulnerable to the delamination. 
       FIG. 6  is a cross sectional view illustrating the bending state of the transparent organic light emitting display apparatus according to one embodiment of the present disclosure, and  FIG. 6  shows that the transparent organic light emitting display apparatus according to one embodiment of the present disclosure is bent at a predetermined angle toward a first direction with respect to the transmission area (TA). 
     Referring to  FIG. 6 , the transparent organic light emitting display apparatus  100  according to one embodiment of the present disclosure includes the undercut area (UA) formed in the transmission area (TA), and the undercut area (UA) can be formed at the side adjacent to the emission area (EA). The undercut area (UA) can be overlapped with at least some of the planarization layer  160 , and the undercut area (UA) can be the area formed by selectively etching at least some portions of the interlayer dielectric and the first protection layer in the transmission area (TA). Accordingly, the encapsulation layer  180  filled in the undercut area (UA) can have the hook-shaped structure so that it is possible to prevent the lower and upper structures of the encapsulation layer  180  from being delaminated by the deformation such as the bending state. Also, although not shown, even though the transparent organic light emitting display apparatus  100  according to one embodiment of the present disclosure is bent in the opposite direction to the bending direction shown in  FIG. 6 , the encapsulation layer  180  formed in the undercut area (UA) can have the same effect as the aforementioned effect. 
       FIGS. 7A to 7G  are cross sectional views illustrating a method for manufacturing the display apparatus according to one embodiment of the present disclosure, which relates to the method for manufacturing the transparent organic light emitting display apparatus shown in  FIG. 3A . Thus, the same reference numbers will be used throughout the drawings to refer to the same or like parts, and a repetitive explanation for the same parts related with each material and structure will be omitted or may be brief. 
     In  FIG. 7A , various elements and layers including the thin film transistor (T), the first and second auxiliary power lines (EVSS 1 , EVSS 2 ), the line contact pattern (LCP), the storage capacitor (Cst), the signal pad (SP), the pad auxiliary electrode (PAE), the light shielding layer (LS), the gate insulating film  130 , and the interlayer dielectric  140  are provided on the substrate  110 . 
     In  FIG. 7B , the first protection layer  150  is disposed over the interlayer dielectric  140 , and the planarization layer  160  can be patterned on the first protection layer  150 . The planarization layer  160  can be patterned on the display area (AA), and more particularly, on the area corresponding to the emission area (EA). Also, the planarization layer  160  can be patterned while protruding toward the transmission area (TA) so as to be overlapped with at least some of the transmission area (TA). 
     Also, the planarization layer  160  can include the contact hole configured to electrically connect the anode electrode (AE) and the contact pad (CP) formed for the following process with the source electrode (SE) and the line contact pattern (LCP) formed therebelow. 
     Then, as shown in  FIG. 7C , after forming the planarization layer  160 , photoresist (PR) can be formed in the predetermined area corresponding to the undercut area (UA) by the photolithography process. The predetermined area corresponding to the undercut area (UA) can be overlapped with at least some of the planarization layer  160  formed by the prior process. 
     Then,  FIG. 7D  shows that the undercut area (UA) is formed by etching the interlayer dielectric  140  and the first protection layer  150  in the area exposed by removing the photoresist of  FIG. 7C . 
     Referring to  FIG. 7D , all the first protection layer  150  corresponding to the undercut area (UA) is etched, and some of the interlayer dielectric  140  is etched. The formation of the undercut area (UA) can be carried out by the wet etching process using the wet etchant, wherein the wet etchant is capable of selectively etching only the interlayer dielectric  140  and the first protection layer  150  without etching the planarization layer  160 . 
     As the undercut area (UA) is formed by the wet etching process, the first protection layer  150  and the interlayer dielectric  140  which remain in the undercut area (UA) for the prior process can be etched. In detail, the etching process is performed only in the uppermost end of the first protection layer  150  exposed by photoresist, and the etched area can radiate isotropically without the etching directivity. 
     Also,  FIG. 7D  shows that the taper angle by the etching is identical. However, if the interlayer dielectric  140  and the first protection layer  150  are formed of the different materials, or are deposited to have the different properties such as hardness, the etching profile with the step difference can be formed by the different taper angles and the different etching levels in accordance with the different etching speeds. 
     Then, as shown in  FIG. 7E , after the anode electrode (AE) and the contact pad (CP) are patterned, the bank (B) can be overlapped with the anode electrode (AE) and the contact pad (CP). 
     Then, as shown in  FIG. 7F , the emission layer (EL), the cathode electrode (CE), and the second protection layer  170  can be sequentially deposited. The step coverage by the deposition process of the emission layer (EL) may be inferior, whereby the emission layer (EL) may not be deposited in the area of the undercut area (UA) overlapped with the planarization layer  160 . Then, the cathode electrode (CE) has the superior step coverage by the deposition process, whereby the cathode electrode (CE) can cover all the lateral surface and lower end portion of the trench formed by the undercut area (UA), and the planarization layer  160  can be deposited in the lower end portion of the planarization layer  160  overlapped with the undercut area (UA). Then, the second protection layer  170  can be manufactured by the CVD process, and the cathode electrode (CE) has the superior step coverage by the CVD process, whereby the second protection layer  170  can cover all the lateral surface and lower end portion of the trench formed by the undercut area (UA), and can cover the cathode electrode (CE) previously deposited in the prior process, and the second protection layer  170  can be deposited in the lower end portion of the planarization layer  160  overlapped with the undercut area (UA). 
     Then, as shown in  FIG. 7G , the emission layer (EL), the cathode electrode (CE), and the second protection layer  170  can be deposited in some area of the undercut area (UA) by the deposition process, and the encapsulation layer  180  can be deposited in the remaining area of the undercut area (UA). Then, in the following process, the second substrate  190  comprising the color filter layer  191  and the black matrix  193  can be formed on the encapsulation layer  180 . 
     The transparent organic light emitting display apparatus according to the present disclosure can be described as follows. 
     According to an embodiment of the present disclosure, a transparent organic light emitting display apparatus comprises an emission area, a transmission area disposed adjacent to the emission area and configured to pass external light, and an undercut area formed in the transmission area, wherein the undercut area is formed by filling an encapsulation layer. 
     According to one or more embodiments of the present disclosure, the transparent organic light emitting display apparatus can further include a planarization layer overlapped with at least some portions of the undercut area. 
     According to one or more embodiments of the present disclosure, the undercut area can be formed as at least one line pattern in the transmission area. 
     According to one or more embodiments of the present disclosure, the undercut area can be configured to have a closed-loop structure in the transmission area. 
     According to one or more embodiments of the present disclosure, the undercut area can be overlapped with or correspond to a plurality of pixels. 
     According to one or more embodiments of the present disclosure, the undercut area can be overlapped with or correspond to a unit pixel. 
     According to one or more embodiments of the present disclosure, the transmission area can include a first substrate, an interlayer dielectric disposed over the first substrate, a first protection layer disposed over the interlayer dielectric, and an encapsulation layer disposed over the first protection layer. 
     According to one or more embodiments of the present disclosure, the undercut area can be formed by selectively etching at least some portions of the interlayer dielectric and the first protection layer. 
     According to one or more embodiments of the present disclosure, the transmission area can further include an emission layer, a cathode electrode, and a second protection layer whose at least some portions are formed between the interlayer dielectric and the encapsulation layer. 
     According to one or more embodiments of the present disclosure, a taper angle of the first protection layer in the undercut area can be larger than a taper angle of the interlayer dielectric in the undercut area. 
     According to one or more embodiments of the present disclosure, a width of the first protection layer in the undercut area can be larger than a width of the interlayer dielectric in the undercut area. 
     According to the embodiment of the present disclosure, a method of manufacturing a transparent organic light emitting display apparatus having an emission area, and a transmission area disposed adjacent to the emission area and configured to pass external light therethrough, comprises sequentially forming an interlayer dielectric and a first protection layer on a first substrate, patterning a planarization layer on the first protection layer, forming an organic light emitting device on the planarization layer, and forming an encapsulation layer and an encapsulation substrate on the organic light emitting device, wherein a step of exposing and etching at least some portions of the transmission area by photolithography is carried out after the step of patterning the planarization layer. 
     According to one or more embodiments of the present disclosure, in the step/process of exposing at least some portions of the transmission area by photolithography after the step of patterning the planarization layer, the exposed area can be partially overlapped with the planarization layer. 
     According to one or more embodiments of the present disclosure, in the step/process of exposing and etching at least some portions of the transmission area by photolithography after the step of patterning the planarization layer, the etching step can be carried out by a wet etching process. 
     In addition to the effects of the present disclosure as mentioned above, additional advantages and features of the present disclosure will be clearly understood by those skilled in the art from the above description of the present disclosure. 
     It will be apparent to those skilled in the art that the present disclosure described above is not limited by the above-described embodiments and the accompanying drawings and that various substitutions, modifications, and variations can be made in the present disclosure without departing from the spirit or scope of the disclosures. Consequently, the scope of the present disclosure is defined by the accompanying claims, and it is intended that all variations or modifications derived from the meaning, scope, and equivalent concept of the claims fall within the scope of the present disclosure. 
     The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments. 
     These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.