OLED panel with inorganic pixel encapsulating barrier
Embodiments described herein relate to sub-pixel circuits and methods of forming sub-pixel circuits that may be utilized in a display such as an organic light-emitting diode (OLED) display. The device includes a plurality of sub-pixels, each sub-pixel of the plurality of sub-pixels defined by adjacent pixel-defining layer (PDL) structures with inorganic overhang structures disposed on the PDL structures, each sub-pixel having an anode, organic light-emitting diode (OLED) material disposed on the anode, and a cathode disposed on the OLED material. The device is made by a process including the steps of: depositing the OLED material and the cathode by evaporation deposition, and depositing an encapsulation layer disposed over the cathode.
1. A method of forming a device, comprising:
positioning a substrate having:
an anode,
adjacent pixel-defining layer (PDL) structures disposed over the substrate, and
inorganic overhang structures defining wells of sub-pixels disposed over an upper surface of the PDL structures, the inorganic overhang structures having an upper portion having a bottom surface contacting and wider than a top surface of a lower portion;
depositing an organic light-emitting diode (OLED) material over the anode;
depositing a cathode over the OLED material, the cathode extending under the inorganic overhang structures adjacent to each sub-pixel and contacting a sidewall of the lower portion of the inorganic overhang structures, a cathode material of the cathode is different from a material of the upper portion;
depositing a first encapsulation layer over the cathode, the first encapsulation layer extends under at least a portion of the inorganic overhang structures past the cathode along the sidewall of the lower portion, and contacts the bottom surface of the upper portion of the inorganic overhang structures; and
depositing a second encapsulation layer over the first encapsulation layer, wherein the second encapsulation layer is disposed within a well of each sub pixel and on the upper portion of the inorganic overhang structures.
2. The method of claim 1 , wherein:
the upper portion comprises a first inorganic material, wherein the first inorganic material is conductive or nonconductive; or
the lower portion comprises a second inorganic material, wherein the second inorganic material is conductive or nonconductive.
3. The method of claim 1 , further comprising an assistant cathode disposed under the lower portion.
4. The method of claim 3 , wherein the cathode contacts a top surface of the assistant cathode.
5. The method of claim 1 , wherein each of the inorganic overhang structures comprises one of:
the upper portion of a non-conductive inorganic material and the lower portion of a conductive inorganic material;
the upper portion of the conductive inorganic material and the lower portion of the conductive inorganic material;
the upper portion of the non-conductive inorganic material, the lower portion of the non-conductive inorganic material, and an assistant cathode disposed under the lower portion; or
the upper portion of the conductive inorganic material, the lower portion of the non-conductive inorganic material, and the assistant cathode disposed under the lower portion.
6. The method of claim 1 , wherein the second encapsulation layer is a global passivation layer.
7. The method of claim 1 , wherein the substrate is a pre-patterned indium tin oxide (ITO) glass substrate.
8. The method of claim 1 , wherein the OLED material comprises a hole injection layer (HIL), a hole transport layer (HTL), an emissive layer (EML), and an electron transport layer (ETL).
9. A method of forming a device, comprising:
positioning a substrate having:
an anode,
adjacent pixel-defining layer (PDL) structures disposed over the substrate, and
inorganic overhang structures defining wells of sub-pixels disposed over an upper surface of the PDL structures, the inorganic overhang structures having an upper portion having a bottom surface contacting and wider than a top surface of a lower portion, wherein
the upper portion comprises a first inorganic material, wherein the first inorganic material is conductive or nonconductive; or
the lower portion comprises a second inorganic material, wherein the second inorganic material is conductive or nonconductive;
depositing an organic light-emitting diode (OLED) material over the anode;
depositing a cathode over the OLED material, the cathode extending under the inorganic overhang structures adjacent to each sub-pixel and contacting a sidewall of the lower portion of the inorganic overhang structures, a cathode material of the cathode is different from a material of the upper portion;
depositing a first encapsulation layer over the cathode, the first encapsulation layer extends under at least a portion of the inorganic overhang structures past the cathode along the sidewall of the lower portion, and contacts the bottom surface of the upper portion of the inorganic overhang structures; and
depositing a second encapsulation layer over the first encapsulation layer, wherein the second encapsulation layer is disposed within a well of each sub pixel and on the upper portion of the inorganic overhang structures.
10. The method of claim 9 , further comprising an assistant cathode disposed under the lower portion.
11. The method of claim 10 , wherein the cathode contacts a top surface of the assistant cathode.
12. The method of claim 9 , wherein each of the inorganic overhang structures comprises one of:
the upper portion of a non-conductive inorganic material and the lower portion of a conductive inorganic material;
the upper portion of the conductive inorganic material and the lower portion of the conductive inorganic material;
the upper portion of the non-conductive inorganic material, the lower portion of the non-conductive inorganic material, and an assistant cathode disposed under the lower portion; or
the upper portion of the conductive inorganic material, the lower portion of the non-conductive inorganic material, and the assistant cathode disposed under the lower portion.
13. The method of claim 9 , wherein the second encapsulation layer is a global passivation layer.
14. The method of claim 9 , wherein the substrate is a pre-patterned indium tin oxide (ITO) glass substrate.
15. The method of claim 9 , wherein the OLED material comprises a hole injection layer (HIL), a hole transport layer (HTL), an emissive layer (EML), and an electron transport layer (ETL).
16. A method of forming a device, comprising:
positioning a substrate having:
an anode,
adjacent pixel-defining layer (PDL) structures disposed over the substrate, and
inorganic overhang structures defining wells of sub-pixels disposed over an upper surface of the PDL structures, the inorganic overhang structures having an upper portion having a bottom surface contacting and wider than a top surface of a lower portion;
depositing an organic light-emitting diode (OLED) material over the anode;
depositing a cathode over the OLED material, the cathode extending under the inorganic overhang structures adjacent to each sub-pixel and contacting a sidewall of the lower portion of the inorganic overhang structures, a cathode material of the cathode is different from a material of the upper portion;
depositing an encapsulation layer over the cathode, the encapsulation layer extends under at least a portion of the inorganic overhang structures past the cathode along the sidewall of the lower portion, and contacts the bottom surface of the upper portion of the inorganic overhang structures; and
disposing a global passivation layer over the encapsulation layer, wherein the global passivation layer is disposed within a well of each sub pixel and on the upper portion of the inorganic overhang structures.