Organic light-emitting diode displays with reflectors
A display may have an array of pixels formed from organic light-emitting diodes and thin-film transistor circuitry. Each pixel may include organic layers interposed between an anode and a cathode. The organic layers may emit out-coupled light that escapes the display and waveguided light that is waveguided within the organic layers. A reflector may be placed at the edge of the organic layers to reflect the waveguided light out of the display. The reflector may be located within a pixel definition layer and may be formed from metal or may be formed from one or more interfaces between high-refractive-index material and low-refractive-index material. The reflector may be formed from an extended portion of the pixel anode. The reflector may be formed from light-reflecting particles that are suspended in the pixel definition layer.
1. An organic light-emitting diode display, comprising:
a substrate having an upper surface;
first and second light-emitting diodes on the substrate each comprising organic layers interposed between a reflective electrode and a transparent electrode;
a pixel definition layer between the first and second light-emitting diodes; and
a reflector embedded within the pixel definition layer, wherein the reflector is separate from the reflective electrode and has a surface that reflects light from the organic layers out of the display through the transparent electrode, and wherein the surface is angled with respect to the upper surface of the substrate.
2. The organic light-emitting diode display defined in claim 1 wherein the reflective electrode and the transparent electrode comprise an anode and a cathode, respectively.
3. The organic light-emitting diode display defined in claim 1 wherein the reflector comprises metal.
4. The organic light-emitting diode display defined in claim 1 wherein the reflector surrounds the first light-emitting diode.
5. The organic light-emitting diode display defined in claim 4 further comprising an additional reflector in the pixel definition layer.
6. The organic light-emitting diode display defined in claim 5 wherein the additional reflector surrounds the second light-emitting diode.
7. The organic light-emitting diode display defined in claim 1 wherein the reflector comprises light-reflective particles suspended in the pixel definition layer.
8. The organic light-emitting diode display defined in claim 7 further comprising a light-blocking layer in the pixel definition layer, wherein a first group of the light-reflective particles are located on a first side of the light-blocking layer and are configured to reflect light emitted from the first light-emitting diode out of the display, and wherein a second group of the light-reflective particles are located on a second side of the light-blocking layer and are configured to reflect light emitted from the second light-emitting diode out of the display.
9. The organic light-emitting diode display defined in claim 1 wherein the pixel definition layer has a refractive index below 1.6.
10. A display, comprising:
a substrate having an upper surface;
a pixel definition layer having an array of openings;
an array of organic light-emitting diodes in the openings, wherein each of the organic light-emitting diodes comprises a transparent electrode; and
a reflector surrounding each organic light-emitting diode in the display, wherein the reflector is located within the pixel definition layer and has a surface that reflects light out of the display through the transparent electrode, wherein the surface is angled with respect to the upper surface of the substrate.
11. The display defined in claim 10 wherein the reflector comprises light-reflective particles.
12. The display defined in claim 10 wherein each organic light-emitting diode has an anode, wherein the anode has a first portion that is parallel to the substrate and a second portion that is angled relative to the substrate, and wherein the second portion forms the reflector.
13. The display defined in claim 10 wherein the transparent electrode comprises a cathode, wherein each organic light-emitting diode has organic layers interposed between an anode and the cathode, and wherein the pixel definition layer has a refractive index that is lower than a refractive index of the organic layers.
14. An organic light-emitting diode pixel, comprising:
a cathode;
an anode having an upper surface;
organic layers between the cathode and the anode, wherein the organic layers emit out-coupled light that escapes the organic light-emitting diode pixel and waveguided light that is waveguided within the organic layers;
a reflector at the edge of the organic layers having a surface that reflects the waveguided light out of the organic light-emitting diode pixel, wherein the surface is angled with respect to the anode; and
a pixel definition layer surrounding the organic light-emitting diode, wherein the reflector is located within the pixel definition layer and is separated from the anode by the pixel definition layer.
15. The organic light-emitting diode pixel defined in claim 14 , wherein the reflector comprises metal.
16. The organic light-emitting diode pixel defined in claim 14 wherein the reflector comprises light-reflecting particles suspended in the pixel definition layer, wherein the pixel definition layer has an opaque portion, and wherein the light-reflecting particles are interposed between the opaque portion and the organic layers.