Organic light-emitting diode display with reduced lateral leakage
An organic light-emitting diode (OLED) display may have an array of organic light-emitting diode pixels that each have OLED layers interposed between a cathode and an anode. Voltage may be applied to the anode of each pixel to control the magnitude of emitted light. The conductivity of the OLED layers may allow leakage current to pass between neighboring anodes in the display. To reduce leakage current and the accompanying cross-talk in a display, the pixel definition layer may disrupt continuity of the OLED layers. The pixel definition layer may have a steep sidewall, a sidewall with an undercut, or a sidewall surface with a plurality of curves to disrupt continuity of the OLED layers. A control gate that is coupled to a bias voltage and covered by gate dielectric may be used to form an organic thin-film transistor that shuts the leakage current channel between adjacent anodes on the display.
1. A display comprising:
a substrate;
an array of pixels that includes first and second organic light-emitting diode pixels, wherein the first organic light-emitting diode pixel includes a first patterned electrode on the substrate and wherein the second organic light-emitting diode pixel includes a second patterned electrode on the substrate;
a pixel definition layer on the substrate that is interposed between the first and second patterned electrodes; and
a laterally conductive layer formed over the pixel definition layer that has a first portion that forms part of the first organic light-emitting diode pixel and a second portion that forms part of the second organic light-emitting diode pixel, wherein the first portion is electrically isolated from the second portion by at least one discontinuity in the laterally conductive layer created by the pixel definition layer, wherein the pixel definition layer comprises a first layer of silicon dioxide, a second layer of silicon dioxide, and a layer of silicon nitride, wherein the layer of silicon nitride is interposed between the first and second layers of silicon dioxide, wherein the pixel definition layer has an upper surface and a sidewall surface, wherein the at least one discontinuity in the laterally conductive layer is created by a recess in the sidewall surface, wherein the first portion of the laterally conductive layer overlaps the first patterned electrode and extends towards but not past the recess in a first direction, and wherein the second portion of the laterally conductive layer overlaps the upper surface of the pixel definition layer and extends towards but not past the recess in a second direction that is opposite the first direction.
2. The display defined in claim 1 , wherein the laterally conductive layer is formed over and in direct contact with the pixel definition layer, the first patterned electrode, and the second patterned electrode.
3. The display defined in claim 2 , further comprising:
an emissive layer formed over the laterally conductive layer; and
a common electrode formed over the emissive layer.
4. A display comprising:
a substrate;
an array of pixels that includes first and second organic light-emitting diode pixels, wherein the first organic light-emitting diode pixel includes a first patterned electrode on the substrate and wherein the second organic light-emitting diode pixel includes a second patterned electrode on the substrate;
a pixel definition layer on the substrate that is interposed between the first and second patterned electrodes; and
a laterally conductive layer formed over the pixel definition layer that has a first portion that forms part of the first organic light-emitting diode pixel and a second portion that forms part of the second organic light-emitting diode pixel, wherein the first portion is electrically isolated from the second portion by at least one discontinuity in the laterally conductive layer created by the pixel definition layer, wherein the pixel definition layer comprises a first layer of material, a second layer of material, and a third layer of material, wherein the first layer of material is interposed between the first patterned electrode and the second layer of material, wherein the second layer of material is interposed between the first layer of material and the third layer of material, wherein the first layer of material has a first sidewall at a first angle relative to an upper surface of the first patterned electrode, wherein the second layer of material has a second sidewall at a second angle relative to the upper surface of the first patterned electrode, wherein the third layer of material has a third sidewall at a third angle relative to the upper surface of the first patterned electrode, wherein the first angle is less than 90 degrees, wherein the second angle is greater than 90 degrees, and wherein the third angle is less than 90 degrees.
5. A display comprising:
a substrate;
an array of pixels that includes first and second pixels, wherein the first pixel includes a first organic light-emitting diode and a first patterned electrode on the substrate and wherein the second pixel includes a second organic light-emitting diode and a second patterned electrode on the substrate;
a common laterally conductive layer that forms part of both the first and second organic light-emitting diodes; and
a structure interposed between the first and second patterned electrodes, wherein the structure reduces an amount of leakage current that passes through the common laterally conductive layer between the first and second patterned electrodes, wherein the structure comprises a conductive contact that is coupled to a bias voltage, wherein the conductive contact is part of a grid with a plurality of openings, and wherein each pixel in the array of pixels is formed in a respective opening of the plurality of openings.
6. The display defined in claim 5 , wherein the conductive contact is formed from the same material as the first and second patterned electrodes.
7. A display comprising:
a substrate;
an array of pixels that includes first and second organic light-emitting diode pixels, wherein the first organic light-emitting diode pixel includes a first patterned electrode on the substrate and wherein the second organic light-emitting diode pixel includes a second patterned electrode on the substrate;
a laterally conductive layer formed over the first and second patterned electrodes that has a first portion that forms part of the first organic light-emitting diode pixel and a second portion that forms part of the second organic light-emitting diode pixel; and
a control gate that is interposed between the first and second patterned electrodes and that is coupled to a bias voltage, wherein the control gate is formed from the same material as the first and second patterned electrodes and wherein the control gate, the first patterned electrode, and the second patterned electrode are coplanar.
8. The display defined in claim 7 , wherein the control gate forms an organic thin-film transistor that shuts a current channel in the laterally conductive layer between the first patterned electrode and the second patterned electrode when coupled to the bias voltage.
9. The display defined in claim 7 , further comprising:
gate dielectric interposed between the control gate and the laterally conductive layer.
10. A display comprising:
a substrate;
an array of pixels that includes first and second organic light-emitting diode pixels, wherein the first organic light-emitting diode pixel includes a first patterned electrode on the substrate and wherein the second organic light-emitting diode pixel includes a second patterned electrode on the substrate;
a laterally conductive layer formed over the first and second patterned electrodes that has a first portion that forms part of the first organic light-emitting diode pixel and a second portion that forms part of the second organic light-emitting diode pixel;
a control gate that is interposed between the first and second patterned electrodes and that is coupled to a bias voltage;
a first contact coupled to the first patterned electrode; and
a second contact coupled to the second patterned electrode, wherein the control gate is formed from the same material as the first and second contacts and wherein the control gate, the first contact, and the second contact are coplanar.
11. The display defined in claim 7 , further comprising:
a pixel definition layer interposed between the first and second patterned electrodes, wherein the pixel definition layer overlaps the control gate.
12. A display comprising:
a substrate;
an array of pixels that includes first and second organic light-emitting diode pixels, wherein the first organic light-emitting diode pixel includes a first patterned electrode on the substrate and wherein the second organic light-emitting diode pixel includes a second patterned electrode on the substrate;
a laterally conductive layer formed over the first and second patterned electrodes that has a first portion that forms part of the first organic light-emitting diode pixel and a second portion that forms part of the second organic light-emitting diode pixel;
a control gate that is interposed between the first and second patterned electrodes and that is coupled to a bias voltage; and
a pixel definition layer interposed between the first and second patterned electrodes, wherein the control gate is embedded within the pixel definition layer.