Visible light emitting diodes fabricated from soluble semiconducting polymers
AssigneeThe Regents of the University of California
InventorsAlan J. Heeger, David Braun
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Abstract
Visible light LEDs are produced having a layer of conjugated polymer which is cast directly from solution or formed as a gel-processed admixture with a carrier polymer. The LEDs can be formed so as to emit polarized light.
Claims26
A light-emitting diode comprising in contact sequence an organic polymer substrate selected from a rigid organic plastic substrate and a flexible transparent organic polymer substrate, an ohmic hole-injecting first electrode comprising a transparent conducting first layer on the substrate, a layer of conjugated polymer on the first electrode, and a rectifying electrode on the layer of conjugated polymer, said diode characterized by emitting visible light and by turning on at voltages below 5 volts and by being formed by the process of:
- i) precoating the substrate with a transparent conducting first layer, said first layer having high work function and serving as an ohmic hole-injecting electrode;
- ii) casting upon said first layer directly from solution, a thin transparent layer of soluble conjugated polymer;
- and
- iii) depositing onto the layer of soluble conjugated polymer, a negative, electron-injecting contact comprising a low work function metal and acting as the rectifying electrode.
A light-emitting diode comprising an unsupported transparent conjugated polymer film itself comprising MEH-PPV and having a first side and a second side with an ohmic hole-injecting first electrode on the first side and a negative electron-injecting rectifying electrode on the second side, such diode characterized by emitting visible light and by turning on at voltages below 5 volts and by being formed by the process which comprises the steps of:
- i) casting a solution of a soluble conjugated polymer and forming a transparent luminescent semiconducting unsupported polymer film having a first side and a second side
- ii) coating the first side of the unsupported polymer film with a transparent conducting first layer, said first layer having a high work function and serving as an ohmic hole-injecting electrode and
- iii) depositing onto the second side of the unsupported polymer film a negative electron-injecting layer comprising a low work function metal and acting as the rectifying electrode.
A light-emitting diode characterized by being capable of emitting polarized visible light, by turning on at voltages below 5 volts and by comprising an unsupported conjugated polymer film, said film having a first and a second side and being formed of an admixture of soluble conjugated polymer and oriented ultra-high molecular weight carrier polymer, said oriented ultra-high molecular weight carrier polymer causing the soluble conjugated polymer to be chain-aligned;
- a transparent, conducting first layer upon one side of said film, said first layer having high work function and serving as an ohmic hole-injecting electrode and a negative electron-injecting contact upon the second side of the film, said electron-injecting contact comprising a low work function metal and acting as the rectifying contact.
A light-emitting diode comprising in contact sequence a substrate, an ohmic hole-injecting first electrode comprising a transparent conducting first layer on the substrate, a layer of conjugated polymer on the first electrode, and a rectifying electrode on the layer of conjugated polymer, said diode characterized by emitting visible light and by turning on at voltages below 5 volts and by being formed by the process of:
- i) precoating the substrate with a transparent conducting first layer, said first layer having high work function and serving as an ohmic hole-injecting electrode;
- ii) casting upon said first layer directly from solution, a thin transparent layer of soluble conjugated polymer comprising MEH-PPV;
- and
- iii) depositing onto the layer of soluble conjugated polymer, a negative, electron-injecting contact comprising a low work function metal and acting as the rectifying electrode.
Dependencies are inferred from the claim text.