US Patent 11031577 Multimodal microcavity OLED with multiple blue emitting layers

A multimodal light-emitting OLED microcavity device, comprising: an opaque substrate; a layer with a reflective surface over the substrate; a first electrode over the reflective surface; organic layers for light-emission including a second blue light-emitting layer closer to the reflective surface and a first blue light-emitting layer further from the reflective layer than the second blue light-emitting layer, where the distance between the midpoints of the second and first blue-light emitting layers is L1, and at least one non-blue light-emitting layer; a semi-transparent second electrode with an innermost surface through which light is emitted; wherein the distance L0 between the reflective surface and the innermost surface of the semi-transparent second electrode is constant over the entire light-emitting area; and the ratio L1/L0 is in the range of 0.30-0.40. The multimodal microcavity OLED has increased blue emission and is particularly useful for use as the light source in a microdisplay.