Electrowetting on demand system with organic transistors
An active matrix fluidic droplet driver system comprising a plurality fluidic droplet pixels driver comprising organic thin-film transistors is described. Each fluidic droplet pixel driver includes an organic thin film transistor and a pixel electrode where the gate dielectric layer and the pixel dielectric layer comprise an organic polymer. The active matrix fluidic droplet driver system can be fabricated on plastic substrates at low temperature and operates at no more than 40 V.
1. A fluidic droplet pixel, the fluidic droplet pixel comprising: a first platform comprising a first substrate, a first pixel electrode disposed on the first substrate, and a first pixel dielectric layer disposed on the first substrate, the first pixel electrode being disposed between the first substrate and the first pixel dielectric layer, the first platform presenting a first hydrophobic surface opposite the first substrate, the first platform further comprising an organic thin film transistor (OTFT) comprising source and drain electrodes separated by an organic semiconductor channel, and a gate electrode separated from the source and drain electrodes by a gate dielectric layer, said organic thin film transistor being disposed between the first substrate and the first hydrophobic surface, and a second platform comprising a second substrate, a second pixel electrode disposed on the second substrate, and a second pixel dielectric layer disposed on the second substrate, the second pixel electrode being disposed between the second substrate and the second pixel dielectric layer, the second platform presenting a second hydrophobic surface opposite the second substrate; wherein the first hydrophobic surface and the second hydrophobic surface define boundaries of a fluidic channel between the first platform and the second platform; and wherein each of the gate dielectric layer, the first pixel dielectric layer, and the second pixel dielectric layer comprise an organic polymer as the major component; and the organic thin film transistor is configured to provide a switchable voltage bias between the first pixel electrode and the second pixel electrode.
2. The fluidic droplet pixel according to claim 1 , wherein the substrate is soda lime glass, or a plastic having a glass transition temperature in the range of 50-250° C.
3. The fluidic droplet pixel according to claim 2 , wherein the substrate is a plastic selected from polyethylene terephthalate, polyethylene naphthalate, and a polyimide.
4. The fluidic droplet pixel according to claim 1 , wherein the drain electrode of the OTFT is also the first pixel electrode.
5. The fluidic droplet pixel according to claim 1 , wherein the drain electrode of the OTFT is in electrical contact with the first pixel electrode.
6. The fluidic droplet pixel according to claim 1 , wherein a planarization layer separates the OTFT from the first pixel electrode by a planarization dielectric layer.
7. The fluidic droplet pixel according to claim 6 , wherein the planarization layer comprises a polymer from structure 4 or 5, or 6.
8. The fluidic droplet pixel according to claim 6 , wherein the planarization dielectric layer is formed from the same chemical composition as the gate dielectric layer.
9. The fluidic droplet pixel according to claim 1 , wherein the first hydrophobic surface is provided by a surface of the first pixel dielectric layer, and/or the second dielectric surface is provided by a surface of the second pixel dielectric layer.
10. The fluidic droplet pixel according to claim 1 , wherein the first hydrophobic surface is provided by a first hydrophobic layer provided on the first platform separate from the first pixel dielectric layer, and/or the second hydrophobic surface is provided by a second hydrophobic layer provided on the second platform separate from the second pixel dielectric layer.
11. The fluidic droplet pixel according to claim 1 wherein the gate dielectric layer has a dielectric constant k greater than 1 and no more than 3.5, and each of first pixel dielectric layer and the second pixel dielectric layer has a dielectric constant k of at least 10 and less than 25.
12. The fluidic droplet pixel according to claim 1 wherein each of the gate dielectric layer, the first pixel dielectric layer and the second pixel dielectric layer has a dielectric constant k of at least 10.
13. The fluidic droplet pixel according to claim 1 wherein the gate dielectric layer comprises a polymer of structure 4 or 5.
14. The fluidic droplet pixel according to claim 1 wherein each of the first pixel dielectric layer and the second pixel dielectric layer comprises a polymer of structure 7.
15. The fluidic droplet pixel according to claim 1 wherein each of the gate dielectric layer, the first pixel dielectric layer and the second pixel dielectric layer comprises a fluorinated polymer.
16. The fluidic droplet pixel according to claim 1 , wherein the first platform further comprises a buffer dielectric layer disposed on the first substrate between the OTFT and the substrate.
17. The fluidic droplet pixel according to claim 16 , wherein the buffer dielectric layer comprises a polymer from structure 4 or 5, or 6.
18. The fluidic droplet pixel according to claim 16 , wherein a planarization layer separates the OTFT from the first pixel electrode by a planarization dielectric layer, and wherein the buffer dielectric layer is formed from the same chemical composition as the gate dielectric layer and the planarization dielectric layer.
19. The fluidic droplet pixel according to claim 1 wherein the organic thin film transistor comprises a core-cyanated perylene small molecule of structure 1A or 1B or 2A or 2B or 3A or 3B as the organic semiconductor.
20. An active matrix fluidic droplet driver system comprising a plurality of fluidic droplet pixels according to claim 1 .