Conductive oxide overhang structures for OLED devices

Abstract

Described herein are sub-pixel circuits and methods of forming the sub-pixel circuits that can be utilized in an organic light emitting diode (OLED) display. The overhang structure is permanent to the sub-pixel circuit. The overhang structure includes a conductive oxide. A first configuration of the overhang structure includes a base portion and a top portion, the top portion being disposed on the base portion. In the first sub-configuration, the base portion includes a conductive oxide of at least one of a TCO material or a TMO material. In the second sub-configuration, the base portion includes a metal alloy material and a conductive oxide on a metal oxide surface. A second configuration of the overhang structure includes a base portion and a top portion, the body portion being disposed between the base portion and the top portion. The body portion includes a metal alloy body and a metal oxide surface.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The embodiments described herein relate generally to displays. More specifically, the embodiments described herein relate to sub-pixel circuits and methods of forming sub-pixel circuits that may be utilized in displays, such as organic light-emitting diode (OLED) displays. [Background technology]

[0002] Input devices, including display devices, may be used in a variety of electronic systems. An organic light-emitting diode (OLED) is a light-emitting diode (LED) in which a light-emitting electroluminescent layer is a film of organic compounds that emits light in response to an electric current. OLED devices are classified as bottom-emitting devices if the emitted light passes through a transparent or semi-transparent bottom electrode and the substrate on which the panel is fabricated. Top-emitting devices are classified based on whether the light emitted from the OLED device exits through a lid that is added after the device is fabricated. OLEDs are used today to create display devices in many electronics technologies. Today's electronics manufacturers are driving to reduce the size of these display devices while providing higher resolution than was possible just a few years ago.

[0003] Patterning of OLED pixels is currently based on processes that limit panel size, pixel resolution, and substrate size. Rather than using fine metal masks, pixels must be patterned using photolithography. Currently, patterning of OLED pixels requires lifting off the organic material after the patterning process. When lift-off occurs, the organic material leaves behind particle issues that impair the OLED's performance. Thus, there is a need in the art for sub-pixel circuits and methods of forming sub-pixel circuits to increase the number of pixels per inch and improve OLED performance. Summary of the Invention

[0004] In one embodiment, a device is provided that includes a substrate, adjacent pixel-defining layer (PDL) structures disposed on the substrate that define subpixels of the device, an overhang structure comprising a conductive oxide disposed on an upper side of the PDL structure, and a plurality of subpixels, each subpixel including an anode, an organic light-emitting diode (OLED) material disposed on and in contact with the anode, and a cathode disposed on the OLED material, where the conductive oxide overhang structure disposed on the upper side of the PDL structure extends over a portion of the OLED material and the cathode.

[0005] In another embodiment, a device is provided, the device including a plurality of subpixels, each subpixel of the plurality of subpixels being defined by adjacent pixel-defining layer (PDL) structures having an overhang structure disposed on the PDL structure, each subpixel having an anode, an organic light-emitting diode (OLED) material disposed on the anode, and a cathode disposed on the OLED material, the overhang structure comprising a conductive oxide. The device is made by a process including: depositing an OLED material on a substrate using an evaporative deposition method, the OLED material being disposed on and in contact with the anode, the OLED material having an OLED edge defined by adjacent overhangs of the conductive oxide overhang structure; and depositing a cathode using an evaporative deposition method, the overhang structure disposed on the PDL structure extending over a portion of the OLED material and the cathode, the overhang structure comprising a conductive oxide.

[0006] In another embodiment, a method is provided. The method includes disposing an overhang layer stack on adjacent pixel defining layer (PDL) structures, each subpixel of a plurality of subpixels being defined by the adjacent PDL structures. The overhang layer stack includes at least a base layer and an overlayer disposed on the base layer. The base layer includes at least one of a transparent conductive oxide (TCO) material, a transition metal oxide (TMO) material, or a metal alloy material. The method includes disposing a resist layer on the overhang layer stack and patterning the resist layer to form a pixel opening in the resist layer, etching the overhang layer stack exposed by the pixel opening to form an overhang structure having an upper portion corresponding to the overlayer and at least a base portion corresponding to the base layer, and depositing an organic light emitting diode (OLED) material and a cathode using evaporative deposition such that the cathode contacts at least a portion of the base portion.

[0007] So that the above-mentioned features of the present disclosure can be understood in detail, a more particular description of the present disclosure briefly summarized above can be had by reference to the embodiments, some of which are illustrated in the accompanying drawings, It should be noted, however, that the accompanying drawings depict only exemplary embodiments and therefore should not be considered as limiting the scope thereof, as other equally effective embodiments may be recognized. [Brief description of the drawings]

[0008] [Figure 1A] FIG. 2 is a schematic cross-sectional view of a sub-pixel circuit according to an embodiment. [Figure 1B] FIG. 2 is a schematic cross-sectional view of a sub-pixel circuit according to an embodiment. [Fig. 1C-1D] 1 is a schematic top cross-sectional view of a sub-pixel circuit according to an embodiment. [Figure 2A] 2 is a schematic cross-sectional view of an overhang structure according to an embodiment. FIG. [Figure 2B] 2 is a schematic cross-sectional view of an overhang structure according to an embodiment. FIG. [Diagram 3]FIG. 2 is a flow diagram of a method for forming a sub-pixel circuit according to an embodiment. [Figure 4A] 1A-1D are schematic cross-sectional views of a portion of a substrate during a method for forming a sub-pixel circuit according to an embodiment. [Figure 4B] 1A-1D are schematic cross-sectional views of a portion of a substrate during a method for forming a sub-pixel circuit according to an embodiment. [Figure 4C] 1A-1D are schematic cross-sectional views of a portion of a substrate during a method for forming a sub-pixel circuit according to an embodiment. [Figure 4D] 1A-1D are schematic cross-sectional views of a portion of a substrate during a method for forming a sub-pixel circuit according to an embodiment. [Figure 4E] 1A-1D are schematic cross-sectional views of a portion of a substrate during a method for forming a sub-pixel circuit according to an embodiment. [Figure 4F] 1A-1D are schematic cross-sectional views of a portion of a substrate during a method for forming a sub-pixel circuit according to an embodiment. [Figure 4G] 1A-1D are schematic cross-sectional views of a portion of a substrate during a method for forming a sub-pixel circuit according to an embodiment. [Figure 4H] 1A-1D are schematic cross-sectional views of a portion of a substrate during a method for forming a sub-pixel circuit according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] For ease of understanding, the same reference numbers have been used, wherever possible, to designate identical elements that are common to each of the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific reference.

[0010] The embodiments described herein generally relate to displays. More specifically, the embodiments described herein relate to sub-pixel circuits and methods for forming sub-pixel circuits that can be used in displays such as organic light-emitting diode (OLED) displays. In one embodiment that can be combined with other embodiments described herein, the display is a bottom-emission (BE) or top-emission (TE) OLED display. In another embodiment that can be combined with other embodiments described herein, the display is a passive matrix (PM) or active matrix (AM) OLED display.

[0011] A first exemplary embodiment of the embodiments described herein includes a subpixel circuit having a dot-type architecture. A second exemplary embodiment of the embodiments described herein includes a subpixel circuit having a line-type architecture. A third exemplary embodiment of the embodiments described herein includes a subpixel circuit having a dot-type architecture with a plug disposed on the encapsulation layer of each subpixel. A fourth exemplary embodiment of the embodiments described herein includes a subpixel circuit having a line-type architecture with a plug disposed on the encapsulation layer of each subpixel.

[0012] Each embodiment of the subpixel circuit described herein includes a plurality of subpixels, each subpixel defined by adjacent overhang structures that are permanent to the subpixel circuit. The overhang structures include a conductive oxide. Although the figures show two subpixels, each subpixel defined by adjacent overhang structures, the subpixel circuit of the embodiments described herein includes a plurality of subpixels, such as two or more subpixels. Each subpixel includes an OLED material configured to emit white, red, green, blue, or other color light when energized. For example, the OLED material of a first subpixel emits red light when energized, the OLED material of a second subpixel emits green light when energized, and the OLED material of a third subpixel emits blue light when energized.

[0013] The overhang structure is permanent to the subpixel circuit. The overhang structure includes a conductive oxide. A first configuration of the overhang structure includes a base portion and a top portion, the top portion being disposed on the base portion. In the first sub-configuration, the base portion includes at least one conductive oxide of a transparent conductive oxide (TCO) material or a transition metal oxide (TMO) material. The TCO material includes, but is not limited to, one or more of indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), indium tin oxide (ITO), or combinations thereof. The TMO material includes a transition metal. A transition metal is an element whose atoms may have a partially filed d-subshell or may form cations with an incomplete d-subshell. Examples of transition metals include, but are not limited to, one or more of oxides of ruthenium (Ru), vanadium (V), titanium (Ti), zinc (Zn), copper (Cu), molybdenum (Mo), or combinations thereof. In a second sub-configuration, the base portion includes a metal alloy material and a conductive oxide of a metal oxide surface. The metal alloy material includes, but is not limited to, copper (Cu), Ti, aluminum (Al), molybdenum (Mo), silver (Ag), tin (Sn), or combinations thereof. The metal oxide surface includes one or more oxides of the metal alloy material.

[0014] A second configuration of the overhang structure includes a base portion and a top portion, with the body portion disposed between the base portion and the top portion. The base portion includes a conductive oxide of at least one of a TCO material or a TMO material. The body portion includes a metal alloy body and a metal oxide surface. The metal alloy body includes a metal alloy material. The top portion includes a metal material, including but not limited to Ti, Cu, Mo, ITO, IZO, or combinations thereof.

[0015] Adjacent overhang structures defining each subpixel of the display's subpixel circuit are formed using evaporative deposition such that the overhang structures remain in place after the subpixel circuit is formed. Evaporative deposition can be utilized to deposit the OLED materials (including the hole injection layer (HIL), hole transport layer (HTL), emissive layer (EML), and electron transport layer (ETL)) and the cathode. One or more of the encapsulation layer, plug, and global encapsulation layer can be disposed by evaporative deposition. The overhang structure extends over a portion of the OLED material and the cathode of the subpixel. The overhang structure defines a deposition angle for each of the OLED material and the cathode such that the OLED material does not contact the overhang structure and the cathode contacts at least a portion of the sidewall of the base of the overhang structure, i.e., provides a shadow effect during evaporative deposition.

[0016] The encapsulation layer of each subpixel is disposed above the cathode with an encapsulation layer. The encapsulation layer may be a local encapsulation layer or may correspond to a local encapsulation layer. The encapsulation layer may extend under at least a portion of each of the adjacent overhang structures. In other embodiments that may be combined with other embodiments described herein, the encapsulation layer may further extend along the sidewalls of each of the adjacent overhang structures. The encapsulation layer may be disposed above the upper side of the top of the overhang structure. A global encapsulation layer may be disposed on the encapsulation layer. The plug of the third and fourth exemplary embodiments may be disposed between the encapsulation layer and the global encapsulation layer. In one example, the global encapsulation layer is conformal to the cathode and the overhang structure. In another example, the global encapsulation layer is non-conformal to the cathode and the overhang structure. The global encapsulation layer may include an inkjet sublayer and a global encapsulation sublayer.

[0017] 1A and 1B are schematic cross-sectional views of a subpixel circuit 100. The subpixel circuit 100 of FIG. 1A includes a first configuration 101A of an overhang structure 110. The overhang structure 110 includes a conductive oxide. The first configuration 101A of the overhang structure 110 includes a base portion 110A and an upper portion 110B, where the upper portion 110B is disposed on the base portion 110A. The subpixel circuit 100 of FIG. 1B includes a second configuration 101B of an overhang structure. The second configuration 101B of the overhang structure 110 includes a base portion 110A and an upper portion 110B, where a body portion 110C is disposed between the base portion and the upper portion.

[0018] The subpixel circuit 100 includes a substrate 102. A metal layer 104 may be patterned on the substrate 102 and is defined by adjacent pixel-defining layer (PDL) structures 126 disposed on the substrate 102. In one embodiment, which may be combined with other embodiments described herein, the metal layer 104 is pre-patterned on the substrate 102. For example, the substrate 102 is a pre-patterned indium tin oxide (ITO) glass substrate. The metal layer 104 is configured to operate the anode of the respective subpixel. The metal layer 104 may include, but is not limited to, chromium, titanium, gold, silver, copper, aluminum, ITO, or combinations thereof, or other suitable conductive materials.

[0019] The PDL structure 126 is disposed on the substrate 102. The PDL structure 126 includes one of an organic material, an organic material having an inorganic coating disposed thereon, or an inorganic material. The organic material of the PDL structure 126 includes, but is not limited to, polyimide. The inorganic material of the PDL structure 126 includes, but is not limited to, silicon oxide (SiO2), silicon nitride (Si3N4), silicon oxynitride (SiON), magnesium fluoride (MgF2), or combinations thereof. Adjacent PDL structures 126 define respective subpixels and expose the anode (i.e., metal layer 104) of each subpixel of the subpixel circuit 100.

[0020] The subpixel circuit 100 includes a plurality of subpixels 106, including at least a first subpixel 108a and a second subpixel 108b. Although the figures show a first subpixel 108a and a second subpixel 108b, the subpixel circuit 100 of the embodiments described herein may include more than one subpixel 106, such as a third and a fourth subpixel. Each subpixel 106 includes an OLED material 112 configured to emit white, red, green, blue, or other color light when energized. For example, the OLED material 112 of the first subpixel 108a emits red light when energized, the OLED material of the second subpixel 108b emits green light when energized, the OLED material of the third subpixel emits blue light when energized, and the OLED material of the fourth subpixel emits another color light when energized.

[0021] An overhang structure 110 is disposed on the upper side 103 of each PDL structure 126. The overhang structure 110 is permanent to the subpixel circuit. Thus, no organic material is left behind from the lifted-off overhang structure that would impair the performance of the OLED. Eliminating the need for a lift-off procedure also improves throughput. The overhang structure 110 further defines each subpixel 106 of the subpixel circuit 100. The overhang structure 110 includes at least a base portion 110A disposed on the upper side 103 of each of the PDL structures 126 (e.g., in the first configuration 101A) and an upper portion 110B disposed on the base portion 110A. At least a lower side 107 of the upper portion 110B is wider than the upper surface 105 of the base portion 110A to form an overhang 109. Body portion 110C of second configuration 101B of overhang structure 110 includes a bottom surface 117 having a width equal to or less than top surface 105 of base portion 110A, and a top surface 119 having a width narrower than lower surface 107 of top portion 110B.

[0022] The underside surface 107 of the top portion 110B, which is larger than the top surface 105 of the base portion 110A forming an overhang 109, allows the top portion 110B to be shadowed by the base portion 110A. The shadow of the overhang 109 allows the evaporative deposition of the OLED material 112 and the cathode 114, respectively. As further explained in the corresponding description of Figures 2A and 2B, the shadow effect of the overhang structure 110 is reduced by the OLED angle θ of the OLED material 112. OLED (shown in FIGS. 2A and 2B ) and the cathode angle θ of the cathode 114 cathode (shown in FIGS. 2A and 2B ). OLED and the cathode angle θ of the cathode 114 cathode may result from evaporative deposition of the OLED material 112 and the cathode 114.

[0023] As shown in FIG. 1A, in the first sub-configuration 125A of the first configuration 101A of the overhang structure 110, the base portion 110A includes at least one conductive oxide of a TCO material or a TMO material. The TCO material includes, but is not limited to, one or more of IZO, IGZO, ITO, or a combination thereof. The TMO material includes a transition metal. A transition metal is an element whose atoms may have a partially filed d-subshell or generate cations with an incomplete d-subshell. Examples of TMO materials include, but are not limited to, one or more of oxides of Ru, V, Ti, Zn, Cu, Mo, or a combination thereof. As shown in FIG. 2B, in the second sub-configuration 125B of the first configuration 101A of the overhang structure 110, the base portion 110A includes a conductive oxide of a metal alloy material and a metal oxide surface 130. The metal alloy material includes, but is not limited to, Cu, Ti, Al, Mo, Ag, Sn, or a combination thereof. The metal oxide surface 130 comprises one or more oxides of a metal alloy material. The second configuration 101B, body portion 110C of the overhang structure 110 includes a metal alloy body 128 having a metal oxide surface 130. The metal alloy body 128 comprises a metal alloy material. The top portion 110B includes a metal material, including, but not limited to, Ti, Cu, Mo, ITO, IZO, or combinations thereof.

[0024] The OLED material 112 may include one or more of an HIL, an HTL, an EML, and an ETL. The OLED material 112 is disposed on the metal layer 104. In some embodiments that can be combined with other embodiments described herein, the OLED material 112 is disposed on the metal layer 104 and on a portion of the PDL structure 126. The cathode 114 is disposed on the OLED material 112 of the PDL structure 126 in each subpixel 106. The cathode 114 is disposed on a portion of the sidewall 111 of the base portion 110A. The cathode 114 includes a conductive material, such as a metal. For example, the cathode 114 includes, but is not limited to, chromium, Ti, Al, ITO, or a combination thereof. In some embodiments shown in FIG. 1B that can be combined with other embodiments described herein, at least one of the OLED material 112 or the cathode 114 is disposed on the upper side surface 115 of the top portion 110B of the overhang structure 110.

[0025] The base portion 110A, which includes at least one of a TCO material or a TMO material, allows the base portion 110A to be exposed to an oxygen-containing plasma and remain conductive. Exposing the overhang structure 110 to an oxygen-containing plasma, i.e., oxidizing the overhang structure 110, removes organic impurities such as a surface monolayer that may remain on the subpixel circuit 100 prior to deposition of the OLED material 112. The TCO material, TMO material, or metal alloy material with a metal oxide surface 130 of the base portion 110A allows the overhang structure 110 to remain conductive. The conductive base portion 110A ensures a permanent connection to the cathode 114.

[0026] Each subpixel 106 includes an encapsulation layer 116. The encapsulation layer 116 may be a local encapsulation layer or may correspond to a local encapsulation layer. The encapsulation layer 116 of each subpixel is disposed over the cathode 114 (and the OLED material 112), and the encapsulation layer 116 extends under at least a portion of each overhang structure 110. As shown in FIG. 1B, in some embodiments that can be combined with other embodiments described herein, the encapsulation layer 116 extends along the sidewall of each overhang structure 110. In other embodiments shown in FIG. 1B that can be combined with other embodiments described herein, the encapsulation layer 116 extends along the sidewall and is disposed on or above the upper surface 115 of the top portion 110B of each overhang structure 110. The encapsulation layer 116 is disposed over the cathode 114. The encapsulation layer 116 includes a non-conductive inorganic material, such as a silicon-containing material. The silicon-containing material may include a Si3N4-containing material.

[0027] In embodiments including one or more capping layers, the capping layer is disposed between the cathode 114 and the encapsulation layer 116. For example, as shown in FIG. 1A, the first capping layer 121 and the second capping layer 123 are disposed between the cathode 114 and the encapsulation layer 116. Although FIG. 1A shows the subpixel circuit 100 having one or more capping layers, each embodiment described herein may include one or more capping layers disposed between the cathode 114 and the encapsulation layer 116. The first capping layer 121 may include an organic material. The second capping layer 123 may include an inorganic material, such as lithium fluoride. The first capping layer 121 and the second capping layer 123 may be deposited by evaporative deposition.

[0028] The global encapsulation layer 120 may be disposed on the encapsulation layer 116. The plug 122 (illustrated by the second subpixel 108b) of the third and fourth exemplary embodiments may be disposed between the encapsulation layer 116 and the global encapsulation layer 120. In one example, the global encapsulation layer is conformal to the cathode 114 and the overhang structure 110, as shown in FIG. 1A. In another example, the global encapsulation layer 120 is non-conformal to the cathode 114 and the overhang structure 110, as shown in FIG. 1B. The global encapsulation layer may include an inkjet sublayer 118a and a global encapsulation sublayer 118b. The inkjet sublayer 118a may include an acrylic material.

[0029] The third and fourth exemplary embodiments (illustrated by the second subpixel in FIG. 1A and FIG. 1B ) include plugs 122 disposed on the encapsulation layer 116. Each plug 122 is disposed within a respective subpixel 106 of the subpixel circuit 100. The plugs 122 may be disposed on the upper side 115 of the upper portion 110B of the overhang structure 110. The plugs 122 include, but are not limited to, a photoresist, a color filter, or a photosensitive monomer. The plugs 122 have a plug transmittance that matches or substantially matches the OLED transmittance of the OLED material 112. The plugs 122 may each be the same material or may match the OLED transmittance. The plugs 122 may be different materials that match the OLED transmittance of each subpixel of the plurality of subpixels 106. The matching or substantially matching of the resist transmittance and the OLED transmittance allows the plugs 122 to remain on the subpixels 106 without blocking the emitted light from the OLED material 112. Because the plugs 122 can remain in place, they do not require a lift-off procedure to be removed from the subpixel circuit 100. Because the plugs 122 remain, there is no need for additional patterned resist material to be placed over the formed subpixels 106 in subsequent operations. By eliminating the need for a lift-off procedure on the plugs 122 and the need for additional patterned resist material on the subpixel circuit 100, throughput is improved.

[0030] FIG 1C is a schematic top cross-sectional view of a subpixel circuit 100 having a dot-type architecture 101C. The dot-type architecture 101C may correspond to the first or third exemplary embodiment of the subpixel circuit 100. FIG 1D is a schematic cross-sectional view of a subpixel circuit 100 having a line-type architecture 101D. The line-type architecture 101D may correspond to the second or fourth exemplary embodiment of the subpixel circuit 100. The top cross-sectional views of FIGS 1C and 1D are taken along section line 1'-1' of FIGS 1A and 1B, respectively.

[0031] The dot-type architecture 101C includes a plurality of pixel openings 124A. Each of the pixel openings 124A is surrounded by an overhang structure 110 that defines each of the subpixels 106 of the dot-type architecture 101C. The line-type architecture 101D includes a plurality of pixel openings 124B. Each of the pixel openings 124B is adjacent to an overhang structure 110 that defines each of the subpixels 106 of the line-type architecture 101D. The overhang structure 110 includes a conductive oxide.

[0032] 2A and 2B are schematic cross-sectional views of the overhang structure 110 of the subpixel circuit 100 of FIGS. 1A and 1B. The overhang structure 110 of FIG. 2A includes a second sub-configuration 125B of a first configuration 101A. The base portion 110A of the overhang structure 110 of the second sub-configuration 125A includes a conductive oxide of a metal alloy material and a metal oxide surface 130. The cathode 114 contacts the metal oxide surface 130. The overhang structure 110 of FIG. 2B includes a second configuration 101B. As shown in FIG. 2B, in some embodiments that can be combined with other embodiments described herein, the body portion 110C includes two or more metal alloy layers, such as a first metal alloy layer 207, a second metal alloy layer 209, and a third metal alloy layer 211. Each of the first metal alloy layer 207, the second metal alloy layer 209, and the third metal alloy layer 211 includes a metal alloy material including, but not limited to, Cu, Ti, Al, Mo, Ag, Sn, or combinations thereof. In an embodiment, the first metal alloy layer and the third metal alloy layer 211 may be the same metal alloy material. In one example, the first metal alloy layer and the third metal alloy layer 211 include Mo, and the second metal alloy layer 209 includes Ti.

[0033] The top portion 110B includes a lower edge 206 and an overhang vector 208. The lower edge 206 extends beyond the sidewall 111 of the base portion 110A such that the overhang structure 110 extends over a portion of the OLED material 112 and the cathode 114. The shadow of the overhang 109 causes the evaporative deposition of each of the OLED material 112 and the cathode 114, and in some embodiments, the first capping layer 121 and / or the second capping layer 123. Each overhang structure 110 includes an overhang 109 defined by an overhang width 203 and an overhang depth 205. The overhang width 203 is from the sidewall 111 of the base portion 110A to the lower edge 206, i.e., the outer edge, of the top portion 110B of the overhang structure 110. The overhang depth 205 is from the PDL 126 to the lower edge 206.

[0034] An overhang vector 208 is defined by the lower edge 206 and the PDL structure 126. The OLED material 112 is disposed on the anode and on the shadowed portion 210 of the PDL structure 126. The OLED material 112 defines an OLED angle θ between the OLED vector 212 and the overhang vector 208. OLED OLED vector 212 is defined by an OLED edge 214 that extends below top portion 110B. In one embodiment, which may be combined with other embodiments described herein, an HIL 204 is included in OLED material 112. In an embodiment that includes an HIL 204, OLED material 112 includes an HTL, an EML, and an ETL. HIL 204 defines an HIL angle θ between HIL vector 216 and overhang vector 208. HIL The HIL vector 216 is defined by an HIL edge 218 that extends below the top portion 110B.

[0035] The cathode 114 is disposed on the OLED material 112 and on the shadowed portion 210 of the PDL structure 126. The cathode 114 is disposed on a portion of the sidewall 111 of the base portion 110A. The cathode 114 has a cathode angle θ between the cathode vector 224 and the overhang vector 208. cathode Cathode vector 224 is defined by a cathode edge 226 that extends under at least upper portion 110B. An encapsulation layer 116 is disposed over cathode 114 (and OLED material 112), with encapsulation layer 116 extending under at least upper portion 110B.

[0036] During evaporative deposition of the OLED material 112, the lower edge 206 of the top portion 110B defines the location of the OLED edge 214. For example, the OLED material 112 is evaporated at an OLED maximum angle corresponding to the OLED vector 212, and the lower edge 206 ensures that the OLED material 112 is not deposited beyond the OLED edge 214. In an embodiment with an HIL 204, the lower edge 206 of the top portion 110B defines the location of the HIL edge 218. For example, the HIL 204 is evaporated at an HIL maximum angle corresponding to the HIL vector 216, and the lower edge 206 ensures that the HIL 204 is not deposited beyond the HIL edge 218. During evaporative deposition of the cathode 114, the lower edge 206 of the top portion 110B defines the location of the cathode edge 226. For example, the cathode 114 is evaporated at a maximum cathode angle corresponding to the cathode vector 224, and the lower edge 206 ensures that the cathode 114 is not deposited beyond the cathode edge 226. The OLED angle θ OLED is the cathode angle θ cathode Smaller than HIL angle θ HIL is the OLED angle θ OLED Less than.

[0037] FIG. 3 is a flow diagram of a method 300 for forming a subpixel circuit 100. FIGS. 4A-4H are schematic cross-sectional views of a portion 400 of a substrate 102 during a method 300 for forming a subpixel circuit 100 according to an embodiment described herein. FIGS. 4A, 4C, 4E, and 4G show an embodiment of a method 300 for forming a subpixel circuit 100 having an overhang structure 110 of a first configuration 101A. FIGS. 4B, 4D, 4F, and 4H show an embodiment of a method 300 for forming a subpixel circuit 100 having an overhang structure 110 of a second configuration 101B. The method 300 may be utilized to fabricate a subpixel circuit 100 of one of the first, second, third, or fourth exemplary embodiments. The portion 400 corresponds to a subpixel 106, such as the first subpixel 108a, of the subpixel circuit 100.

[0038] In operation 301, an overhang layer stack 402 is disposed on the substrate 102, as shown in FIG. 4A and FIG. 4B. In an embodiment of the first configuration 101A, the overhang layer stack 402 includes a base layer 402A corresponding to the base portion 110A and an upper layer 402B corresponding to the upper portion 110B, as shown in FIG. 4A. In an embodiment of the second configuration 101B, the overhang layer stack 402 includes a base layer 402A, a body layer 402C corresponding to the body portion 110C, and an upper layer 402B, as shown in FIG. 4B. The base layer 402A is disposed on the PDL structure 126 and the metal layer 104. The base layer 402A includes at least one of a TCO or TMO material of the first sub-configuration 125A or a metal alloy material of the second sub-configuration 125B. The body layer 402C includes a metal alloy material. The upper layer 402B includes a metal material.

[0039] In operation 302, a resist 404 is deposited and patterned, as shown in FIG. 4C and FIG. 4D. The resist 404 is deposited on the top layer 402B. The resist 404 is a positive resist or a negative resist. The chemical composition of the resist 404 determines whether the resist is a positive resist or a negative resist. The resist 404 is patterned to form one of the pixel openings 124A of the dot-type architecture 101C or the pixel openings 124B of the line-type architecture 101D of the sub-pixel 106. The patterning is either a photolithography, a digital lithography process, or a laser ablation process.

[0040] In operation 303, a portion of the overhang layer stack 402 is etched, as shown in FIG. 4E and FIG. 4F. The portions of the top layer 402B and the base layer 402A (and the body layer 402C of the second configuration 101B) exposed by the pixel openings 124A, 124B are removed by an etching process. Operation 303 forms the overhang structure 110 of the subpixel 106. The etching process for forming the overhang structure 110 of the first configuration 101A utilizes a top layer etching chemistry and a base layer etching chemistry. The etching process for forming the overhang structure 110 of the second configuration 101B utilizes a top layer etching chemistry, a body layer etching chemistry, and a base layer etching chemistry. The top layer etching chemistry includes a dry etching chemistry. The body layer etching chemistry and the base layer include a wet etching chemistry. In some embodiments, which can be combined with other embodiments described herein, the body layer etching chemistry and the base layer etching chemistry include the same wet etching chemistry. Wet etch chemistries include, but are not limited to, sulfuric acid, nitric acid, acetic acid, or combinations thereof.

[0041] In the embodiment of the first configuration 101A, the etching chemistry of the top layer, e.g., dry etching chemistry, and the etching chemistry of the base layer are selected based on the composition of the top layer 402B and the base layer 402A to form the base portion 110A and the top portion 110B of the overhang structure 110. The etching selectivity between the materials of the top layer 402B and the base layer 402A and the etching process to remove the exposed portions of the top layer 402B and the base layer 402A provide a lower surface 107 of the top portion 110B that is wider than the upper surface 105 of the base portion 110A to form the overhang 109.

[0042] In the embodiment of the second configuration 101B, the top layer etch chemistry, e.g., dry etch chemistry, and the body layer etch chemistry and base layer etch chemistry are selected based on the composition of the top layer 402B, the body layer 402C, and the base layer 402A to form the base portion 110A, the body portion 110C, and the top portion 110B of the overhang structure 110. The etch selectivity between the materials of the top layer 402B, the body layer 402C, and the base layer 402A, and the etching process to remove the exposed portions of the top layer 402B and the base layer 402A provide a lower surface 107 of the top portion 110B that is wider than the upper surface 105 of the base portion 110A to form the overhang 109. The wet etch chemistry etches the portion of the body layer 402C faster than the base layer 402A. The shadow of the overhang 109 causes the OLED material 112 and the cathode 114 to be evaporated and deposited. After act 303, the resist 404 is removed.

[0043] The TCO and / or TMO materials of the base layer 402A allow the body layer 402C and the base layer 402A to be etched simultaneously because the TCO and / or TMO materials etch at a slower rate than the metal alloy material of the body layer 402C. The base layer 402A also protects the top layer 402B, and in some embodiments, the metal layer 104, from exposure to the etchant when the body layer 402C is etched, as a thin layer of the base layer 402A may remain after the top layer etch chemistry and the body layer etch chemistry are used. The base layer etch chemistry can be used to etch the thin protective layer remaining from the base layer 402A. At least the selection of the TCO and / or TMO materials of the base layer 402A, the metal material of the top layer 402B (in some embodiments, the metal alloy material of the body layer 402C), and the chemistry of the etching process provides for the formation of the overhang structure 110 having a uniform overhang depth 205. The overhang structures 110 of the subpixel circuit 100 include overhang widths 203 that are between about 0.5 μm (micrometers) and about 1 μm. Each overhang width 203 of the overhang structures 110 is within about 15 percent of each other.

[0044] In operation 304, the overhang structure 110 is oxidized. The overhang structure 110 is oxidized by exposure to an oxygen-containing plasma, such as O2 plasma. In the second sub-configuration 125B of the first configuration 101A, a metal oxide surface 130 is formed on the metal alloy material by exposing the base portion 110A to an oxygen-containing plasma, as shown in FIG. 2A and FIG. 4G. In the embodiment of the second configuration 101B, a metal oxide surface 130 is formed on the metal alloy body 128 formed in operation 303 by exposing the body portion 110C to an oxygen-containing plasma, as shown in FIG. 1B, FIG. 2B, and FIG. 4H. Exposing the overhang structure 110 to an oxygen-containing plasma, i.e., oxidizing the overhang structure 110, removes organic impurities, such as a surface monolayer, that may remain on the subpixel circuit 100 prior to deposition of the OLED material 112.

[0045] In operation 305, OLED material 112, cathode 114, and encapsulation layer 116 are deposited, as shown in Figures 4G and 4H. The shadow of overhang 109 causes the OLED material 112 and cathode 114 to be evaporatively deposited, respectively. As further explained in the corresponding description of Figures 2A and 2B, the shadow effect of overhang structure 110 is reduced by the OLED angle θ of OLED material 112. OLED and the cathode angle θ (of cathode 114) cathode The OLED angle θ of the OLED material 112 is defined as OLED and the cathode angle θ of the cathode 114 cathode 4G, a plug 122 is disposed between the encapsulation layer 116 and the global encapsulation layer 120. The global encapsulation layer 120 may include an inkjet sublayer 118a and a global encapsulation sublayer 118b. In some embodiments, which may be combined with other embodiments described herein, one or more capping layers, such as a first capping layer 121 and a second capping layer 123, are disposed between the cathode 114 and the encapsulation layer 116. In operation 306, a global encapsulation layer 120 is disposed. In some embodiments, as shown in FIG. 4G, a plug 122 is disposed between the encapsulation layer 116 and the global encapsulation layer 120. The global encapsulation layer 120 may include an inkjet sublayer 118a and a global encapsulation sublayer 118b.

[0046] In summary, described herein are subpixel circuits and methods of forming the subpixel circuits that may be utilized in displays, such as organic light emitting diode (OLED) displays. Adjacent overhang structures that define each subpixel of the subpixel circuit of the display are formed using evaporative deposition such that the overhang structures remain in place after the subpixel circuit is formed. Evaporative deposition may be utilized for deposition of the OLED material and the cathode. The overhang structures define the deposition angle, i.e., provide a shadow effect during evaporative deposition. The base portion, which includes at least one of a TCO material, a TMO material, or a metal alloy material with a metal oxide surface, allows the base portion to be exposed to an oxygen-containing plasma and remain conductive. Exposing the overhang structure to an oxygen-containing plasma, i.e., oxidizing the overhang structure, removes organic impurities, such as a surface monolayer, that may remain on the subpixel circuit 100 prior to deposition of the OLED material. The TCO material, the TMO material, or the metal alloy material with a metal oxide surface ensures that the overhang structures remain conductive and permanently connect the base portion and the cathode.

[0047] While the forgoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, which scope is determined by the following claims.

Claims

1. A substrate, an overhang structure disposed on an upper side of the substrate; a plurality of sub-pixels, each sub-pixel being defined by a first overhang structure and a second overhang structure adjacent to one another; wherein each subpixel comprises: The first overhang structure and the second overhang structure, a base portion disposed on the upper surface of the substrate, the base portion comprising a first composition; a body portion disposed on the base portion and including a second composition; a top portion disposed on the body portion and including a third composition; the first overhang structure and the second overhang structure, a first extension of the upper portion of the first overhang structure extending laterally beyond a first sidewall of the base portion and the body portion, and a second extension of the upper portion of the second overhang structure extending laterally beyond a second sidewall of the base portion and the body portion; An anode; an organic light emitting diode (OLED) material disposed over the anode; a cathode disposed on the OLED material, the cathode extending under the first extension of the upper portion of the first overhang structure and the second extension of the upper portion of the second overhang structure; Including, the device.

2. The first composition comprises: transition metals, a transition metal oxide (TMO) material, or Transparent Conductive Oxide (TCO) materials, The device of claim 1 , comprising at least one of:

3. the transition metal comprises ruthenium (Ru), vanadium (V), titanium (Ti), zinc (Zn), copper (Cu), molybdenum (Mo), or a combination thereof; the TMO material comprises one or more oxides of the transition metals; the TCO material comprises one or more of indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), indium tin oxide (ITO), or combinations thereof; The device of claim 2.

4. The device of claim 1 , wherein the second composition comprises a metal alloy material.

5. 5. The device of claim 4, wherein the metal alloy material comprises copper (Cu), titanium (Ti), aluminum (Al), molybdenum (Mo), silver (Ag), tin (Sn), or a combination thereof.

6. The device of claim 4 , wherein the body further comprises a metal oxide surface.

7. The device of claim 6 , wherein the metal oxide surface comprises one or more oxides of the metal alloy material.

8. The device of claim 1 , wherein the third composition comprises a metallic material.

9. The device of claim 8 , wherein the metallic material comprises Ti, Cu, Mo, ITO, IZO, or a combination thereof.

10. Adjacent overhangs of the overhang structure are an overhang width from a side wall of the base portion to a lower surface of the upper portion; an overhang depth from the PDL structure to the lower surface of the top portion; and The device of claim 1 , wherein:

11. 11. The device of claim 10, wherein the overhang width of each of the overhang structures is from about 0.5 μm (micrometers) to about 1 μm and within 15 percent of each other.

12. The device of claim 1 further comprising an encapsulation layer disposed on the cathode.

13. The encapsulation layer comprises: at the first sidewall in contact with the base portion of the first composition; at lower surfaces of the first extension and the second extension so as to contact the upper portion of the third composition; and on at least a first portion of an upper surface of the first extension of the upper portion of the first overhang structure and an upper surface of the second extension of the upper portion of the second overhang structure, The device of claim 12 , wherein the device is elongated.

14. The device of claim 13 , wherein the encapsulation layer extends into contact with the body portions of the first and second overhang structures.

15. 13. The device of claim 12, wherein each subpixel further comprises a plug disposed on the encapsulation layer, the plug having a plug transmittance that matches or substantially matches an OLED transmittance of the OLED material.

16. The device of claim 12 , further comprising a global encapsulation layer disposed over the first overhang structure, the second overhang structure, and the encapsulation layer.

17. The device of claim 1 , wherein the device comprises a dot-based architecture or a line-based architecture.

18. The device of claim 1 , wherein the substrate is a pre-patterned indium tin oxide (ITO) glass substrate.

19. A substrate, an overhang structure disposed on an upper side of the substrate; a plurality of sub-pixels, each sub-pixel being defined by a first overhang structure and a second overhang structure adjacent to each other; wherein each subpixel comprises: The first overhang structure and the second overhang structure, a base portion disposed on the upper surface of the substrate, the base portion comprising a first composition; a top portion disposed over the base portion and including a second composition; a first extension of the upper portion of the first overhang structure extending laterally beyond the base portion and a second extension of the upper portion of the second overhang structure extending laterally beyond the base portion; An anode; an organic light emitting diode (OLED) material disposed over the anode; a cathode disposed over the OLED material, the cathode extending under the first extension of the upper portion of the first overhang structure and the second extension of the upper portion of the second overhang structure; Including, the device.

20. The first composition comprises: a transition metal oxide (TMO) material; A transparent conductive oxide (TCO); 20. The device of claim 19, comprising at least one of:

21. The base portion having the first composition is Metal alloy body including metal alloy material 20. The device of claim 19, comprising:

22. 22. The device of claim 21, wherein the metal alloy material comprises copper (Cu), titanium (Ti), aluminum (Al), molybdenum (Mo), silver (Ag), tin (Sn), or a combination thereof.

23. 23. The device of claim 22, wherein a metal oxide surface is disposed on the metal alloy body.

24. The device of claim 19 , wherein the second composition comprises a metallic material.

25. 25. The device of claim 24, wherein the metallic material comprises Ti, Cu, Mo, ITO, IZO, or a combination thereof.

26. A substrate, an overhang structure comprising a conductive oxide disposed on an upper surface of the substrate; A plurality of sub-pixels; wherein each subpixel comprises: a base portion disposed on the upper surface of the substrate, the base portion comprising a first composition; a top portion disposed over the base portion and including a second composition different from the first composition, the top portion extending laterally beyond the base portion; An anode; an organic light emitting diode (OLED) material disposed over the anode; a cathode disposed over the OLED material, the overhanging structure extending over a portion of the OLED material and the cathode; and Including, the device.

27. The first composition comprises: Transparent Conductive Oxide (TCO) materials, a transition metal oxide (TMO) material, or a metal alloy body comprising a metal alloy material; and a metal oxide surface comprising one or more oxides of said metal alloy material; 27. The device of claim 26, comprising at least one of:

28. 30. The device of claim 27, further comprising a body portion disposed between said base portion and said top portion, said body portion having said metal alloy body and said metal oxide surface.

29. 28. The device of claim 27, wherein the metal alloy material comprises copper (Cu), titanium (Ti), aluminum (Al), molybdenum (Mo), silver (Ag), tin (Sn), or a combination thereof.

30. the TCO material comprises one or more of indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), indium tin oxide (ITO), or combinations thereof; the TMO material comprises an oxide of a transition metal; The upper metal material comprises Ti, Cu, Mo, ITO, IZO, or a combination thereof; 28. The device of claim 27.

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