Abstract:
An organic light emitting display device capable of preventing outgassing from a pixel defining layer (PDL) or a planarization layer and method of manufacturing the same.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0068007, filed on Jul. 14, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Aspects of embodiments according to the present invention relate to an organic light emitting display device and a method of manufacturing the same. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, a flat panel display device may be categorized as a light-emitting type display device or as a light-receiving type display device. Light-emitting type display devices include flat cathode ray tubes, plasma display panels, electroluminescent display devices, light emitting diode display devices, or the like. Light-receiving type display devices include liquid crystal displays (LCDs) or the like. Among these display devices, electroluminescent display devices are expected to become next generation display devices due to their wide viewing angle, high contrast, and fast response speed. An electroluminescent display device may be an inorganic electroluminescent device or an organic electroluminescent device (e.g., organic light emitting display device), according to a material that forms an emitting layer (EML). 
         [0006]    In this regard, the organic electroluminescent device is a self light-emitting type display device that emits light by electrically exciting a fluorescent organic compound. The organic electroluminescent device can be driven at a low voltage, can be made thin, and can solve problems related to a wide viewing angle and fast response speed of an LCD. Thus the organic electroluminescent device is expected to become a next generation display device. 
         [0007]    The organic electroluminescent device includes an EML formed of an organic material between an anode electrode and a cathode electrode. In the organic electroluminescent device, when a positive voltage and a negative voltage are applied to the anode electrode and the cathode electrode, respectively, holes that are injected from the anode electrode move to the EML via a hole transport layer (HTL), and electrons from the cathode electrode move to the EML via an electron transport layer (ETL), so that the electrons and the holes are recombined in the EML to generate excitons. 
         [0008]    When the excitons are changed from an excitation state to a ground state, fluorescent molecules in the EML emit light that may form an image. In the case of a full color type organic electroluminescent device, a full color spectrum is realized by having pixels that respectively emit red (R), green (G), and blue (B) colors. 
         [0009]    In the organic electroluminescent device, a pixel defining layer (PDL) is formed at edges of the anode electrode, a predetermined aperture is formed in the PDL, and then the EML and the cathode electrode are sequentially formed above a portion of the anode electrode that is externally exposed due to the aperture. 
       SUMMARY 
       [0010]    Embodiments according to the present invention provide an organic light emitting display device and a method of manufacturing the same, whereby it is possible to prevent outgassing of gas or moisture from an organic layer to an organic emitting layer (EML), and/or to prevent gas or moisture from the outside from entering the organic EML. 
         [0011]    According to an aspect of the present invention, there is provided an organic light emitting display device including a substrate; a pixel circuit arranged above the substrate; a pixel electrode electrically connected to the pixel circuit; a pixel defining layer (PDL) exposing the pixel electrode; an intermediate layer arranged on the pixel electrode and configured to radiate light; and a first ion injected layer formed on the PDL. 
         [0012]    The first ion injected layer may be formed by injecting ions into the PDL. 
         [0013]    The ions may be BHx+ or PH+. 
         [0014]    The first ion injected layer may be formed by heating the PDL at 200° C. and then injecting the ions into the PDL. 
         [0015]    A thickness of the first ion injected layer may be 2000 Å to 3000 Å. 
         [0016]    The PDL may be formed of an organic material, and the first ion injected layer may prevent gas from being discharged from the PDL. 
         [0017]    The organic light emitting display device may further include a planarization layer that is arranged between the pixel electrode and the pixel circuit and covers the pixel circuit. 
         [0018]    The planarization layer may include a contact hole for connection between the pixel electrode and the pixel circuit. 
         [0019]    A second ion injected layer may be formed on the planarization layer. 
         [0020]    The second ion injected layer may be formed by injecting ions into the planarization layer. 
         [0021]    The ions may be BHx+ or PH+. 
         [0022]    The second ion injected layer may be formed by heating the PDL at 200° C. and then injecting the ions into the planarization layer. 
         [0023]    A thickness of the second ion injected layer may be 2000 Å to 3000 Å. 
         [0024]    The second ion injected layer may prevent gas from being discharged from the planarization layer. 
         [0025]    The pixel circuit may include a thin film transistor (TFT). 
         [0026]    According to another aspect of the present invention, there is provided a method of manufacturing an organic light emitting display device, the method including the operations of forming a pixel circuit above a substrate; forming a passivation layer on the pixel circuit; forming a planarization layer on the passivation layer; forming a pixel electrode on the planarization layer; forming a PDL on the planarization layer so as to expose the pixel electrode; and forming a first ion injected layer on the PDL. 
         [0027]    The operation of forming the first ion injected layer may include the operations of hardening the PDL; and injecting ions into the PDL. 
         [0028]    The ions may be BHx+ or PH+. 
         [0029]    The operation of injecting the ions may include the operation of forming the first ion injected layer by injecting the ions into a surface of the PDL. 
         [0030]    A thickness of the first ion injected layer may be 2000 Å to 3000 Å. 
         [0031]    The operation of hardening the PDL may include the operation of heating the PDL at 200° C. 
         [0032]    After the operation of forming the planarization layer, the method may further include the operation of forming a second ion injected layer on the planarization layer. 
         [0033]    The operation of forming the second ion injected layer may include the operations of hardening the planarization layer; and injecting ions into the planarization layer. 
         [0034]    The ions may be BHx+ or PH+. 
         [0035]    The operation of injecting the ions may include the operation of forming the second ion injected layer by injecting the ions into a surface of the planarization layer. 
         [0036]    A thickness of the second ion injected layer may be 2000 Å to 3000 Å. 
         [0037]    The operation of hardening the planarization layer may include the operation of heating the planarization layer at 200° C. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]    The above and other features and aspects of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0039]      FIG. 1  is a cross-sectional view of a pixel circuit according to an embodiment of the present invention; 
           [0040]      FIG. 2  is a schematic plan view of an organic light emitting display device according to another embodiment of the present invention; 
           [0041]      FIG. 3  is a cross-sectional view of an organic light emitting display device according to another embodiment of the present invention; and 
           [0042]      FIG. 4  is a cross-sectional view of an organic light emitting display device according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0043]    Hereinafter, the present invention will be described in detail by explaining exemplary embodiments of the invention with reference to the attached drawings. 
         [0044]      FIG. 1  is a cross-sectional view of a pixel circuit according to an embodiment of the present invention. 
         [0045]    Referring to  FIG. 1 , the pixel circuit may be a thin film transistor (TFT). The TFT may be arranged on a substrate  20 . The substrate  20  may include a glass substrate or a plastic substrate. 
         [0046]    A buffer layer  21  is formed on the substrate  20 , an active layer  22  formed of a semiconductor material is arranged on the buffer layer  21 , and a gate insulating layer  23  is formed to cover the active layer  22 . A gate electrode  24  is formed on the gate-insulating layer  23 , an interlayer insulating layer  25  is formed to cover the gate electrode  24 , and source/drain electrodes  26  and  27  are formed on the interlayer insulating layer  25 . The source/drain electrodes  26  and  27  contact source/drain regions  22   b  and  22   c  of the active layer  22 , respectively, via contact holes that are formed in the gate-insulating layer  23  and the interlayer insulating layer  25 . 
         [0047]    The active layer  22  above the substrate  20  may be formed of an inorganic semiconductor or an organic semiconductor, and includes the source/drain regions  22   b  and  22   c  doped respectively with n-type and p-type impurities, and a channel region  22   a  connecting the source/drain regions  22   b  and  22   c.    
         [0048]    Inorganic semiconductors that may form the active layer  22  may include one or more of CdS, GaS, ZnS, CdSe, CaSe, ZnSe, CdTe, SiC, and Si. 
         [0049]    The organic semiconductor that may form the active layer  22  may include one or more of a polymer material including polythiophen or derivatives thereof, polyphenylenevinylene or derivatives thereof, polyfluorene or derivatives thereof, polythiophenevinylene or derivatives thereof, or polythiophen-heterocyclic aromatic copolymer or derivatives thereof, or may include a small-molecular material including pentacene, tetracene, oligoacene of naphthalene or derivatives thereof, alpha-6-thiophen, oligothiophen of alpha-5-thiophen or derivatives thereof, metallic or non-metallic phthalocyanine or derivatives thereof, pyromellitic dianhydride or pyromellitic diimide or derivatives thereof, or perylenetetracarboxylic dianhydride or perylenetetracarboxylic diimide or derivatives thereof. 
         [0050]    The active layer  22  is covered by the gate-insulating layer  23 , and the gate electrode  24  is formed on the gate-insulating layer  23 . The gate electrode  24  may be formed as a conductive metallic layer including MoW, Al, Cr, Al/Cu, or the like. However, a material forming the gate electrode  24  is not limited thereto, and thus various types of conductive materials including a conductive polymer material may be used to form the gate electrode  24 . The gate electrode  24  is formed to cover a region corresponding to the channel region  22   a  of the active layer  22 . 
         [0051]      FIG. 2  is a schematic plan view of an organic light emitting display device according to another embodiment of the present invention. 
         [0052]    Referring to  FIG. 2 , the organic light emitting display device includes a display region  30 , and circuit regions  40  at edges of the display region  30 . The display region  30  includes a plurality of pixels, and each of the pixels includes a light-emission unit that emits light so as to realize an image. 
         [0053]    According to the present embodiment, the light-emission unit is formed of a plurality of sub-pixels, each having an organic light emitting element device. In a full color organic light emitting display device, red (R), green (G), and blue (B) sub-pixels constitute a pixel by being arranged in various patterns including a line, a mosaic, a lattice, or the like. However, in some embodiments, the organic light emitting display device may not be a full color organic light emitting display device but may be a mono color organic light emitting display device. 
         [0054]    The circuit regions  40  control an image signal that is input to the display region  30 . 
         [0055]    In the organic light emitting display device, at least one TFT may be arranged in the display region  30  and at least one TFT may be arranged in each of the circuit regions  40 . 
         [0056]    The at least one TFT that is arranged in the display region  30  includes a pixel-unit TFT including a switching TFT for controlling an operation of a light-emitting device by delivering a data signal to the light-emitting device according to a signal of a gate line, and a driving TFT for driving a current to flow in an organic light emitting element device according to a data signal. The at least one TFT that is arranged in each of the circuit regions  40  includes a circuit-unit TFT for embodying a circuit (e.g., a predetermined circuit). 
         [0057]    The number of the TFTs and arrangement for the TFTs may vary according to characteristics of displays, and method of driving the displays. 
         [0058]      FIG. 3  is a cross-sectional view of an organic light emitting display device  100  according to another embodiment of the present invention. 
         [0059]    Referring to  FIG. 3 , a buffer layer  51  is arranged on a substrate  50  that is formed of a glass material or a plastic material, and a TFT, as a device circuit unit (or pixel circuit), and an organic light emitting element device may be formed thereon. 
         [0060]    An active layer  52  having a pattern (e.g., a predetermined pattern) is arranged on the buffer layer  51  on the substrate  50 . A gate insulating layer  53  is arranged on the active layer  52 , and a gate electrode  54  is formed (e.g., in a predetermined region) on the gate insulating layer  53 . The gate electrode  54  is connected to a gate line (not shown) for applying TFT on/off signals. An interlayer insulating layer  55  is formed on the gate electrode  54 , and source/drain electrodes  56  and  57  are formed to contact source/drain regions  52   b  and  52   c  of the active layer  52 , respectively, via contact holes. A passivation layer  58  that is formed of SiO 2  or SiNx is arranged on the source/drain electrodes  56  and  57 , and a planarization layer  59  that is formed of an organic material including acryl, polyimide, benzocyclobutene (BCB), or the like may be formed on the passivation layer  58 . 
         [0061]    A pixel electrode  161  that functions as an anode electrode of the organic light emitting element device is formed on the planarization layer  59 , and a pixel defining layer (PDL)  160  is formed to cover the pixel electrode  161 . The PDL  160  may be formed of an organic material. 
         [0062]    After an aperture (e.g., a predetermined aperture) is formed in the PDL  160 , an intermediate layer  162  is formed on the PDL  160  and on a top surface of the pixel electrode  161  externally exposed by the formed aperture. Here, the intermediate layer  162  includes an EML. However, a structure of the organic light emitting display device  100  according to the present embodiment is not limited thereto, and thus the organic light emitting display device  100  may have a structure of any of various organic light emitting display devices. 
         [0063]    A first ion injected layer  171  (e.g., a first protection layer) is formed on the PDL  160 . The first ion injected layer  171  is formed by injecting ions into a surface of the PDL  160 , which may be formed of an organic material. The ions injected into the surface of the PDL  160  may be BHx+ or PH+. The ions are injected from the surface of the PDL  160  to a depth of about 2000 Å to 3000 Å to form the first ion injected layer  171 . Thus, a thickness of the first ion injected layer  171  may be about 2000 Å to 3000 Å. 
         [0064]    The first ion injected layer  171  is formed by heating the PDL  160 , which may be formed of the organic material, at about 200° C., hardening the PDL  160 , and then injecting BHx+ or PH+ into the surface of the PDL  160  by using an ion injecting apparatus. The first ion injected layer  171  may have a Diamond Like Carbon (DLC) structure on the PDL  160 . For example, the BHx+or PH+ions may be injected using the ion injecting apparatus by applying an ion acceleration voltage of 80 to 100 kV using gases such as, for example, B 2 H 6  or PH 3 . 
         [0065]    The first ion injected layer  171  may prevent outgassing from the PDL  160 . That is, since the PDL  160  is formed of an organic material, gas or moisture existing in the PDL  160  may be discharged from the PDL  160  while or after the organic light emitting display device  100  is manufactured. The gas or moisture discharged from the PDL  160  may react with the intermediate layer  162  including the EML, and reduce a lifetime of the organic light emitting display device  100 . However, in the present embodiment, the first ion injected layer  171  is formed on the PDL  160 , so that it is possible to prevent gas or moisture in the PDL  160  from being discharged to the outside. Accordingly, the first ion injected layer  171  may prevent reduction of the lifetime of the organic light emitting display device  100  due to outgassing from the PDL  160 . 
         [0066]    The organic light emitting element device emits red, green, and blue light according to a flow of a current, and thus displays image information. The organic light emitting element device (e.g., organic light emitting diode) is formed of the pixel electrode  161 , an opposite electrode  163 , and the intermediate layer  162 , wherein the pixel electrode  161  is electrically connected to the drain electrode  57  of the TFT and receives a positive voltage, the opposite electrode  163  is formed to cover an entire pixel and supplies a negative voltage to the intermediate layer  162 , and the intermediate layer  162  is located between the pixel electrode  161  and the opposite electrode  163  and may emit light. 
         [0067]    The pixel electrode  161  and the opposite electrode  163  are insulated from each other by the intermediate layer  162 , and cause light-emission to be performed in the intermediate layer  162  by supplying a positive voltage and a negative voltage to the intermediate layer  162 . 
         [0068]    Here, the intermediate layer  162  may be formed as a small-molecular organic layer or a polymer organic layer. In a case where the intermediate layer  162  is formed as the small-molecular organic layer, the intermediate layer  162  may have a single or multi-layered structure in which a hole injection layer (HIL), a hole transport layer (HTL), an EML, an electron transport layer (ETL), and an electron injection layer (EIL) are stacked. An organic material that may be possibly used as the small-molecular organic layer includes copper phthalocyanine (CuPc), N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), tris-8-hydroxyquinoline aluminum)(Alq 3 ), and the like. The small-molecular organic layer may be formed by performing vacuum deposition. 
         [0069]    In a case where the intermediate layer  162  is formed as the polymer organic layer, the intermediate layer  162  may have a structure in which an HTL and an EML are arranged. Here, the HTL may be formed of poly-(2,4)-ethylene-dihydroxy thiophene (PEDOT), and the EML may be formed of a polymer organic material including a Poly-Phenylenevinylene (PPV) based material, a polyfluorene-based material, or the like. The HTL and the EML may be formed by performing a screen coating method or an inkjet printing method. 
         [0070]    However, a type of the intermediate layer  162  is not limited thereto, and thus any of various types may be applied to the intermediate layer  162 . 
         [0071]    The intermediate layer  162  may be formed by performing a spin coating method. In more detail, an organic material is coated to cover the pixel electrode  161  and the PDL  160 . Afterward, the substrate  50  is spun. According to the amount of spin of the substrate  50 , the organic material coated on the PDL  160  is removed, and only the organic material coated on the pixel electrode  161  remains. Next, the organic material coated on the pixel electrode  161  is fired to form the intermediate layer  162 . 
         [0072]    The pixel electrode  161  functions as an anode electrode, and the opposite electrode  163  functions as a cathode electrode, or vice versa. 
         [0073]    The pixel electrode  161  may be formed as a transparent electrode or a reflective electrode. When the pixel electrode  161  is a transparent electrode, the pixel electrode  161  may be formed of a material including ITO, IZO, ZnO, or In 2 O 3 , and when the pixel electrode  161  is a reflective electrode, the pixel electrode  161  may be formed in a manner in which a reflective layer is formed of a material selected from the group consisting of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, and compounds thereof, and then a material including ITO, IZO, ZnO, or In 2 O 3  and having a high work function is formed thereon. 
         [0074]    Meanwhile, the opposite electrode  163  may be formed as a transparent electrode or a reflective electrode. When the opposite electrode  163  is a transparent electrode, the opposite electrode  163  functions as the cathode electrode, and thus the opposite electrode  163  is formed in a manner in which metal having a low work function and selected from the group consisting of Li, Ca, LiF/Ca, LiF/Al, Al, Ag, Mg, and compounds thereof, may be deposited so as to face the opposite electrode  163 , and then an auxiliary electrode layer or a bus electrode line may be formed thereon by using a transparent electrode forming material including ITO, IZO, ZnO, or In 2 O 3 . When the opposite electrode  163  is a reflective electrode, the opposite electrode  163  is formed of a material selected from the group consisting of Li, Ca, LiF/Ca, LiF/Al, Al, Ag, Mg, and compounds thereof by deposition. 
         [0075]      FIG. 4  is a cross-sectional view of an organic light emitting display device  200  according to another embodiment of the present invention. 
         [0076]    The organic light emitting display device  200  of  FIG. 4  is different from the organic light emitting display device  100  of  FIG. 3  in that a second ion injected layer  172  is formed on the planarization layer  59 . 
         [0077]    In more detail, the second ion injected layer  172  (e.g., a second protection layer) may be formed on the planarization layer  59 . The second ion injected layer  172  is formed by injecting ions into a surface of the planarization layer  59  that may be an organic material. The ions injected into the surface of the planarization layer  59  may be BHx+ or PH+. The ions are injected from the surface of the planarization layer  59  to a depth of about 2000 Å to 3000 Å to form the second ion injected layer  172 . Thus, a thickness of the second ion injected layer  172  may be about 2000 Å to 3000 Å. 
         [0078]    The second ion injected layer  172  is formed by heating the planarization layer  59 , which may be the organic material, at about 200° C., hardening the planarization layer  59 , and then injecting BHx+ or PH+ into the surface of the planarization layer  59  by using an ion injecting apparatus. The second ion injected layer  172  may have a DLC structure on the planarization layer  59 . 
         [0079]    The second ion injected layer  172  may prevent outgassing from the planarization layer  59 . That is, since the planarization layer  59  is formed of an organic material, gas or moisture existing in the planarization layer  59  may be discharged from the planarization layer  59  while or after the organic light emitting display device  200  is manufactured. The gas or moisture discharged from the planarization layer  59  may react with the intermediate layer  162  including the EML, and reduce a lifetime of the organic light emitting display device  200 . However, in the present embodiment, the second ion injected layer  172  is formed on the planarization layer  59 , so that it is possible to prevent gas or moisture in the planarization layer  59  from being discharged to the outside. Accordingly, the second ion injected layer  172  may prevent reduction of the lifetime of the organic light emitting display device  200  due to outgassing from the planarization layer  59 . 
         [0080]    According to the one or more embodiments of the present invention, it is possible to prevent external gas from penetrating to an organic emitting layer, or to prevent outgassing from an organic layer including a PDL. 
         [0081]    While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims and their equivalents.