Organic light-emitting diode display with pixel definition layers
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 an undercut to disrupt continuity of some but not all of the OLED layers. The undercut may be defined by three discrete portions of the pixel definition layer. The undercut may result in a void that is interposed between different portions of the OLED layers to break a leakage path formed by the OLED layers.
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 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, wherein the second portion is electrically isolated from the first portion by a void that is at least partially defined by an undercut in an edge of the pixel definition layer, wherein the pixel definition layer has a first portion formed from a first material, a second portion formed from a second material that is different than the first material, and a third portion that is interposed between the second portion of the pixel definition layer and the first patterned electrode, wherein the first portion of the pixel definition layer extends past an edge of the second portion of the pixel definition layer to define the undercut in the edge of the pixel definition layer, and wherein the undercut has a height that is a distance between a lower surface of the first portion of the pixel definition layer and an upper surface of the third portion of the pixel definition layer.
2. The display defined in claim 1 , wherein the first material is silicon dioxide and wherein the second material is silicon nitride.
3. The display defined in claim 1 , wherein the undercut has a width that is a distance between an edge of the first portion of the pixel definition layer and the edge of the second portion of the pixel definition layer.
4. The display defined in claim 3 , wherein the width of the undercut is more than fifteen nanometers.
5. The display defined in claim 1 , wherein the height of the undercut is more than twenty nanometers.
6. The display defined in claim 1 , wherein the third portion of the pixel definition layer extends past an edge of the first portion of the pixel definition layer.
7. The display defined in claim 6 , wherein the first portion of the pixel definition layer is formed from silicon dioxide, wherein the second portion of the pixel definition layer is formed from silicon nitride, and wherein the third portion of the pixel definition layer is formed from silicon dioxide.
8. The display defined in claim 1 , wherein the conductive layer is a first conductive layer, the display further comprising:
a second conductive layer formed over the first conductive layer, wherein the second conductive layer has a third portion that forms part of the first organic light-emitting diode pixel and a fourth portion and wherein the third portion of the second conductive layer is electrically isolated from the fourth portion of the second conductive layer by the void; and
a third conductive layer formed over the second conductive layer, wherein the third conductive layer has a fifth portion that is formed over the third portion of the second conductive layer, wherein the third conductive layer has a sixth portion that is formed over the fourth portion of the second conductive layer, wherein the fifth portion of the third conductive layer forms part of the first organic light-emitting diode pixel, and wherein the fifth and sixth portions of the third conductive layer are electrically connected and are not interrupted by the void.
9. The display defined in claim 8 , wherein the second conductive layer has a higher conductivity than the third conductive layer.
10. The display defined in claim 8 , wherein the second conductive layer comprises a charge generation layer.
11. 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; and
an opaque pixel definition layer on the substrate that is interposed between the first and second patterned electrodes, wherein the pixel definition layer includes a first portion that is formed on a top surface of the first patterned electrode, a second portion that is formed on a top surface of the first portion and that has an edge, and a third portion that is formed on a top surface of the second portion and that has an edge and wherein the edge of the third portion extends past the edge of the second portion towards a center of the first patterned electrode.
12. The display defined in claim 11 , wherein the top surface of the first portion of the pixel definition layer is overlapped by both the second and third portions of the pixel definition layer in a first region, is overlapped by neither the second nor third portion of the pixel definition layer in a second region, and is overlapped by only the third portion of the pixel definition layer in a third region that is interposed between the first and second regions.
13. 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; and
an opaque pixel definition layer on the substrate that is interposed between the first and second patterned electrodes, wherein the pixel definition layer includes a first portion that is formed on the first patterned electrode, a second portion that is formed on the first portion and that has an edge, and a third portion that is formed on the second portion and that has an edge, wherein the edge of the third portion extends past the edge of the second portion towards a center of the first patterned electrode, wherein the first portion of the pixel definition layer is a layer of silicon dioxide, wherein the second portion of the pixel definition layer is a layer of silicon nitride, and wherein the third portion of the pixel definition layer is a layer of silicon dioxide.