Flexible panel display having thin film transistors driving polymer light-emitting diodes

• US 5,747,928 A
• Filed: 10/07/1994
• Issued: 05/05/1998
• Est. Priority Date: 10/07/1994
• Status: Expired due to Term

• Current Assignee: Iowa State University Research Foundation Incorporated (Iowa State University)
• Original Assignee: Iowa State University Research Foundation Incorporated (Iowa State University)
• Inventors: Jeffrey, Frank R. III, Burns, Stanley G., Shanks, Howard R.
• Primary Examiner(s): Patel, Ashok
• Application Number:
  US08/320,029
• Time in Patent Office: 1,306 Days
• Field of Search: 313/498, 313/499, 313/500, 313/501, 313/502, 313/505, 313/506, 313/509, 313/512, 313/504, 345/76, 315/169.3, 428/917, 428/696
• US Class Current: 313/498
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 2102/311 Flexible OLED
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/122 Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals

Abstract

A non-planar electronic light-emitting display has a display area divided into a matrix of pixels. Each pixel includes two primary elements, an electronic driver and a light-emitting diode based on a light-emitting polymer. The electronic driver is a thin film transistor device of amorphous silicon formed on the insulating substrate. The diode has a first electrode connected to and driven by the electronic transistor, a layer of light-emitting polymer deposited on the electrode, and an overlying electrode normally biased on. Energization of the driver biases the diode to cause the polymer to emit light. Each pixel is configured with the two-component structure described above, and row and column lines to the matrix of pixels are decoded by the drivers to cause selective illumination of the pixels.

Claims

1. A solid state electronic light emitting display device of non-planar configuration and having driving transistors distributed in a display area and sharing pixels with light-emitting display elements, the display device comprising, in combination:

a non-planar substrate;

at least one metallization and interconnect layer carried by the substrate;

an interface carried by the substrate and including semiconductor devices configured and interconnected for selectively driving the pixels of the display device, the interface being connected to the interconnect layer;

the display area on the substrate being divided into a plurality of pixels, each pixel including;

a thin film transistor including layers of α

-Si;

H and dielectric forming a transistor structure having sufficient current capacity for driving a light-emitting means in the associated pixel;

a first electrode connected to and driven by the thin film transistor, the first electrode covering the majority of the pixel area;

a light-emitting polymer deposited on the first electrode;

a transparent electrode covering the light-emitting polymer such that said electrodes and said polymer form said light-emitting means by injecting carriers into the polymer under the control of the thin film transistor;

the thin film transistor being connected to the interconnect layer for receipt of drive signals from the interface; and

the interconnect layer being configured to interconnect the interface with the thin film transistors for selective energization of the respective thin film transistors and thereby selective illumination of the pixels.

2. The combination as set forth in claim 1 wherein the light-emitting polymer is a PPA electroluminescent polymer, the first electrode driven by the thin film transistor comprising an aluminum electrode adapted to inject electrons into the polymer, and the transparent electrode covering the light-emitting polymer comprising an ITO electrode adapted to inject holes into the polymer.

3. The combination as set forth in claim 1 wherein the light-emitting polymer is a PPV electroluminescent polymer, one of the electrodes adapted to inject electrons into the polymer, and the other electrode adapted to inject holes into the polymer.

4. The combination as set forth in claim 1 wherein the first electrode is an aluminum electrode occupying the majority of the area of the pixel, and the transparent electrode is an ITO electrode which covers a plurality of pixels.

5. The combination as set forth in claim 1 wherein the thin film transistor comprises a gate layer deposited on the substrate, a dielectric deposited on the gate layer, an α

-Si;

H layer deposited on the dielectric layer and having doped source and drain regions at the surface thereof, and electrodes connected to the source, drain and gate of the thin film transistor for interconnecting said transistor with the interface and with the first electrode.

6. The combination as set forth in claim 1 wherein the non-planar substrate is a flexible polyimide sheet.

7. The combination as set forth in claim 1 wherein the display device is configured in a data card containing an on-board data memory and carrying the display area for display of information stored in said memory, the data card being a wallet-sized card of laminated plastic construction.

8. The combination as set forth in claim 1 wherein the interface comprises a plurality of interface connected thin film transistors deposited on the substrate, said interface connected thin film transistors comprising gate layers carried by the substrate, dielectric layers deposited over the gate layers, α

-Si;

H layers on the dielectric layers and doped source and drain regions at the surface of the α

-Si;

H layers.

9. The combination as set forth in claim 8 wherein at least some of the interface connected thin film transistors comprise floating gate thin film transistors having a floating gate embedded in the dielectric layer and adapted for storage of information.