US 6,784,602 B2 · Organic electroluminescent device

Abstract

The present invention provides a novel organic electroluminescent device having an optical interference member which reduces the overall reflectance from the device. The invention is particularly suited to current-driven organic displays having an anode, an electroluminescent layer and a cathode, where at least one optical interference member is placed between two of the layers and thus forms part of the electrical circuit required to excite the display. The optical interference member is chosen to have a thickness which causes at least some destructive optical interference of ambient light incident on the display. In addition, the material(s) of the optical interference member are chosen to have a work function which is compatible with the highest occupied molecular orbital, or the lowest unoccupied molecular orbital of the electroluminescent layer, depending on the location of the optical interference member in relation to the anode, cathode and electroluminescent layer.

Claims25

Dependent claims

An electroluminescent device for displaying an image to a viewer in front of said device, comprising:

an anode layer, being said front and being substantially transparent to electroluminescent light;
a cathode layer being reflective to ambient light;
an organic electroluminescent layer made from tris(8-quinolinolato aluminium) (Alq3) and disposed between said cathode layer and said anode layer, said electroluminescent layer having a highest occupied molecular orbital associated with an anode side, and a lowest unoccupied molecular orbital associated with a cathode side;
and
a semi-absorbent layer and a transparent layer together forming an optical interference member that is disposed between said electroluminescent layer and said cathode, said semi-absorbing layer being closer to said electroluminescent layer than said transparent layer, said member having a work function (ΦOIM) about equal to an amount of energy required to extract an electron from said lowest unoccupied molecular orbital (ELUMO), said member causing at least some destructive optical interference of ambient light at a pre-selected wavelength to reduce reflectance of ambient light towards said viewer.

2 more elements

Dependencies are inferred from the claim text.

Organic electroluminescent device

Life of this patent

Organic electroluminescent device

Life of this patent

Abstract

Claims25