Method of manufacture of active matrix addressed polymer LED display
View Patent ↗A display having a plurality of light emitting pixels. Each pixels includes an isolation transistor, a driving circuit, and an organic light emitting diode (OLED). The driving circuit storing a value that determines the magnitude of the light emitted by that pixels, the driving circuit placing the OLED in a conducting path between the first and second power terminals. The driving circuit is programmed through the isolation transistor. In one embodiment of the present invention, the driving circuit includes a storage capacitor and a driving transistor. The OLEDs are part of an array of OLEDs. The array of OLEDs is constructed on a flexible sheet having first and second surfaces, the flexible sheet being transparent to light of a first wavelength. A transparent first electrode layer is in contact with the first surface. A light emitting layer including an organic polymer is in contact with the first electrode layer. A plurality of second electrodes, one such second electrode corresponding to each of the OLEDs, is in contact with the light emitting layer. Each second electrode has an isolated conducting area. The driving transistor are part of a transistor array having a plurality of connection points disposed on a surface, each connection point corresponding to one of the second electrodes in the array of OLEDs. The connection points are arranged such that each second electrode overlies the corresponding connection point when the array of OLEDs is properly aligned with the transistor array. The connection points are bonded to the corresponding second electrodes by a bonding layer.
1. A display comprising a plurality of light emitting pixels, each pixel comprising an isolation transistor, a driving circuit, and an organic light emitting diode (OLED), said driving circuit storing a value that determines the magnitude of the light emitted by that pixel, said driving circuit placing said OLED in a conducting path between first and second power terminals, said isolation transistor connecting said driving circuit to a bit line when said isolation transistor is placed in a conducting state by the application of a logic signal to a word line, wherein said OLEDs are part of an array of OLEDs, said array of OLEDs comprising:
a flexible sheet having first and second surfaces, said first and second surfaces being parallel to one another, said flexible sheet being transparent to light of a first wavelength;
a first electrode comprising a first electrode layer in contact with said first surface, said first electrode layer being transparent to light of said first wavelength;
a light emitting layer comprising an organic polymer in electrical contact with said first electrode layer; and
a plurality of second electrodes, one such second electrode corresponding to each OLED, each of said second electrodes comprising an isolated conducting area in electrical contact with said light emitting layer, said light emitting layer generating light of said first wavelength in a region adjacent to said second electrode when a potential difference is applied across said first and second electrodes,
wherein said driving circuit comprises a storage capacitor and a driving transistor, and wherein said driving transistor is part of a transistor array having a plurality of connection points disposed on a surface, each of said connection points corresponding to one of said second electrodes in said array of OLEDs, said connection points being arranged such that each second electrode overlies said corresponding connection point when said array of OLEDs is properly aligned with said transistor array, and wherein said display further comprises a bonding layer comprising an anisotropic conductive adhesive located between said transistor array and said array of OLEDs, said bonding layer being in contact with a plurality of said connection points, said bonding layer electrically connecting each of said second electrodes to that connection point corresponding to that second electrode without electrically connecting any one of said second electrodes to a connection point that does not correspond to that second electrode.
2. The display of claim 1 wherein said bonding layer comprises compressible electrically conducting particles suspended in an electrically insulating adhesive.
3. The display of claim 1 further comprising a light conversion layer in contact with said second surface of said flexible sheet, said light conversion layer absorbing light of said first wavelength and emitting light of a second wavelength.
4. The display of claim 1 wherein said driving transistor are part of an array of thin film transistors.
5. A display comprising a plurality of light emitting pixels, said display comprising an array of driving transistors and an array of OLEDs, said array of OLEDs comprising:
a flexible sheet having first and second surfaces, said first and second surfaces being parallel to one another, said flexible sheet being transparent to light of a first wavelength;
a first electrode comprising a first electrode layer in contact with said first surface, said first electrode layer being transparent to light of said first wavelength;
a light emitting layer comprising an organic polymer in electrical contact with said first electrode layer; and
a plurality of second electrodes, one such second electrode corresponding to each OLED, each of said second electrodes comprising an isolated conducting area in contact with said light emitting layer, said light emitting layer generating light of said first wavelength in a region adjacent to said second electrode when a potential difference is applied across said first and second electrodes,
wherein said array of driving transistors is part of a transistor array having a plurality of connection points disposed on a surface, each of said connection points corresponding to one of said second electrodes in said array of OLEDs, said connection points being arranged such that each second electrode overlies said corresponding connection point when said array of OLEDs is properly aligned with said transistor array, and wherein said display further comprises a bonding layer comprising an anisotropic conductive adhesive located between said transistor array and said array of OLEDs, said bonding layer being in contact with a plurality of said connection points, said bonding layer electrically connecting each of said second electrodes to that connection point corresponding to that second electrode without electrically connecting any one of said second electrodes to a connection point that does not correspond to that second electrode.
6. The display of claim 5 wherein said bonding layer comprises compressible electrically conducting particles suspended in an electrically insulating adhesive.
7. The display of claim 5 further comprising a light conversion layer in contact with said second surface of said flexible sheet, said light conversion layer absorbing light of said first wavelength and emitting light of a second wavelength.
8. The display of claim 5 wherein said driving transistor are part of an array of thin film transistors.