Display containing improved pixel architectures
The invention relates to improved Organic Light Emitting Transistor (OLET) pixel architecture for OLET based displays.
1. A display containing an array of pixels, wherein each pixel comprises at least a first driving transistor and at least a second light emitting transistor mounted on a common substrate adjacent the first driving transistor, wherein the first driving transistor is a lateral channel field effect transistor that comprises the following elements:
a first source electrode and a first drain electrode physically separated but electrically connected to each other by a semiconductor layer,
a first dielectric layer, and
at least one first gate electrode, and
the second light emitting transistor is a lateral channel field effect transistor that comprises the following elements:
a second gate electrode,
a second dielectric layer,
a light emitting channel layer, and
a second source electrode having a length Ls and a second drain electrode having a length Ld,
wherein the second gate electrode is in electrical contact with the first source electrode and/or the first drain electrode, and
characterized in that at least one of the second source electrode and the second drain electrode vertically overlaps with the second gate by at least 5 μm, such vertical overlaps being represented by L and L′, respectively, and that said second source electrode and second drain electrode are horizontally separated by at least 2 μm.
2. A display according to claim 1 wherein said vertical overlap(s) L and/or L′ are between 5 μm and 150 μm.
3. A display according to claim 1 wherein said second source electrode and said second drain electrode are horizontally separated by a distance between 2 μm and 50 μm.
4. A display according to claim 1 wherein each of said second source electrode and said second drain electrode vertically overlaps with said second gate electrode by at least 5 μm.
5. A display according to claim 1 wherein the entire length Ls of said second source electrode and the entire length Ld of second drain electrode vertically overlap with said second gate electrode, wherein said second gate electrode has a length that is greater than the sum of Ls, Ld, and the horizontal separation between said second source electrode and said second drain electrode.
6. A display according to claim 1 wherein the length of the second source electrode (Ls) and the length of the second drain electrode (Ld) are chosen in accordance to the following formula:
1≤Maximum( Ld,Ls )/Minimum( Ld,Ls )≤25.
7. A display according to claim 1 wherein at least one of said second source electrode and said second drain electrode is in contact with both the light emitting channel layer and the second dielectric layer.
8. A display according to claim 1 wherein the light emitting channel layer is ambipolar.
9. A display according to claim 1 wherein said second light emitting transistor comprises a third source or drain electrode disposed in such a way that source and drain electrodes alternate horizontally.
10. A display according to claim 1 comprising a reflecting layer above or below the light emitting channel layer.
11. A display according to claim 1 wherein said first source electrode and said first drain electrode are positioned both above or both below the semiconductor layer.
12. A display according to claim 1 wherein the first gate electrode is positioned below the semiconductor layer.
13. A display according to claim 1 wherein the first gate electrode is positioned above the semiconductor layer.
14. A display according to claim 1 wherein the second source and second drain electrodes comprise at least one different material which is not comprised in the other of said second source and second drain electrodes.
15. A display according to claim 14 wherein said at least one different material is in the form of an interposed layer deposit or an interposed layer component, said interposed layer being placed between the at least one of said second source and second drain electrodes and the light emitting channel layer.
16. A display according to claim 1 wherein at least one of the first source and first drain electrodes of the first driving transistor is at least partially beneath one of the second source and second drain electrodes.
17. A display according to claim 16 wherein at least 10% of the area of the first driving transistor is beneath one of the second source and second drain electrodes of the second light emitting transistor.
18. A display according to claim 1 wherein one of the first source and first drain electrodes of the first driving transistor is adapted to function also as the second gate electrode of the second light emitting transistor.
19. A display according to claim 18 wherein the first dielectric layer of the first driving transistor is adapted to function also as the second dielectric layer of the second light emitting transistor.
20. A display according to claim 1 wherein
said vertical overlap(s) L and/or L′ are between 5 μm and 150 μm;
said second source electrode and said second drain electrode are horizontally separated by a distance between 2 μm and 50 μm; and
the entire length Ls of said second source electrode and the entire length Ld of second drain electrode vertically overlap with said second gate electrode, wherein said second gate electrode has a length that is greater than the sum of Ls, Ld, and the horizontal separation between said second source electrode and said second drain electrode.
21. A display according to claim 1 wherein Ls and Ld satisfy the following formula:
1≤Maximum( Ld,Ls )/Minimum( Ld,Ls )≤25.