Electroluminescent device
AssigneeCambridge Display Technology Limited
InventorsPaul May, Karl Pichler
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Abstract
An electroluminescent device is described which utilizes a “memory effect” which allows a device to be turned on by a turn on voltage and then for the voltage to be reduced without a reduction in the light output. The present electroluminescent device incorporates a semiconductive conjugated polymer layer together with a light dependent voltage regulating layer the conductivity of which varies with light incident thereon from the semiconductive conjugated polymer layer. An electroluminescent device using a semiconductive conjugated polymer layer is relatively simple to manufacture as compared with earlier devices.
Claims15
An electroluminescent device comprising:
- first and second electrodes;
- and,
- arranged between said first and second electrodes, a first layer of a semiconductive conjugated polymer acting as an electroluminescent layer and a second layer of a semiconductive conjugated polymer acting as a light dependent voltage regulating layer a conductivity of which varies with light incident thereon from the electroluminescent layer,
- wherein bandgaps of the semiconductive conjugated polymers constituting the first and second layers are selected to be close to one another but with offset energy levels.
An electroluminescent device comprising:
- a first electrode associated with an electroluminescent layer;
- a second electrode associated with a photoconductive layer;
- and
- a third electrode located between the electroluminescent layer and the photoconductive layer;
- and
- wherein the third electrode defines with the first electrode an electroluminescent unit and wherein there is a fourth electrode which defines with the second electrode a photoconductive unit, wherein light generated by the electroluminescent unit is incident on the photoconductive layer of the photoconductive unit.
Dependencies are inferred from the claim text.