Organic triodes with novel grid structures and method of production
An organic semiconductor device is provided. The device has a first electrode and a second electrode, with an organic semiconductor layer disposed between the first and second electrodes. An electrically conductive grid is disposed within the organic semiconductor layer, which has openings in which the organic semiconductor layer is present. At least one insulating layer is disposed adjacent to the electrically conductive grid, preferably such that the electrically conductive grid is completely separated from the organic semiconductor layer by the insulating layer. Methods of fabricating the device, and the electrically conductive grid in particular, are also provided. In one method, openings are formed in an electrically conductive layer with a patterned die, which is then removed. In another method, an electrically conductive layer and a first insulating layer are etched through the mask to expose portions of a first electrode. In yet another method, a patterned die is pressed into a first organic semiconductor layer to create texture in the surface of the first organic semiconductor layer, and then removed. An electrically conductive material is then deposited onto the first organic semiconductor layer from an angle to form a grid having openings as a result of the textured surface and the angular deposition. In each of the methods, insulating layers are preferably deposited or otherwise formed during the process to completely separate the electrically conductive layer from previously and subsequently deposited organic semiconductor layers.
1. A method of fabricating a device, comprising the steps of:
(a) depositing a first insulating layer onto a first electrode;
(b) depositing an electrically conductive layer onto the first insulating layer;
(c) creating a patterned mask on top of the first electrically conductive layer by a method comprising the steps of: (i) depositing a monolayer of substantially close-packed particles; (ii) exposing the particles to a process that reduces their size, thereby creating gaps between the particles; (iii) depositing a mask material into the gaps between the particles; and (iv) removing the particles and any mask material deposited thereon;
(d) etching the electrically conductive layer and the first insulating layer through the mask to form holes of an average diameter or width of less than about 100 nm to expose portions of the first electrode;
(e) depositing an organic semiconductor layer over the exposed portions of the first electrode, first insulating layer, and first electrically conductive layer; and
(f) depositing a second electrode over the organic semiconductor layer.
2. The method of claim 1 , further comprising the step of:
depositing a second insulating layer onto the first electrically conductive layer after step (b) and prior to step (c);
wherein the patterned mask is created on top of the second insulating layer during step (c);
wherein the second insulating layer is also etched during step (d); and
wherein the organic semiconductor layer is also deposited over the second insulating layer during step (e).
3. The method of claim 2 , further comprising the step of:
oxidizing any exposed portion of the electrically conductive layer after step (d) and before step (e) to form an additional insulating layer.
4. The method of claim 1 , further comprising the step of:
depositing a side insulating layer that covers any exposed portion of the electrically conductive layer, after step (d) and before step (e).
5. The method of claim 1 , wherein the mask is removed after step (d) and before step (e).
6. The method of claim 1 , wherein the particles are spherical.
7. The method of claim 1 , wherein the particles are made of polystyrene.
8. The method of claim 1 , wherein the particles are made of alumina.
9. The method of claim 1 , wherein the particles are made of sapphire.
10. The method of claim 1 , wherein the particles are made of gold.
11. The method of claim 1 , wherein the organic semiconducting layer is a hole conducting material, and the electrically conductive layer comprises a metal having a work function greater than about 5 eV.
12. The method of claim 1 , wherein the organic semiconducting layer is an electron conducting material, and the electrically conductive layer comprises a metal having a work function less than about 4 eV.
13. The method of claim 1 , wherein the electrically conductive layer comprises a material selected from the group consisting of gold and aluminum, and the insulating layer comprises SiN x .
14. The method of claim 1 , wherein the insulating layer comprises a material selected from the group consisting of SiN x and SiO 2 .
15. The method of claim 1 , wherein the electrically conductive layer has a thickness of about 10-50 nm.
16. The method of claim 1 , wherein the insulating layer has a thickness of about 5-50 nm.
17. The method of claim 1 , wherein the organic semiconductor layer has a thickness of about 20-200 nm.
18. The method of claim 1 , wherein the average diameter of the holes is less than about 50 nm.
19. The method of claim 1 , wherein the particles are 100 nm beads.