Memory device based on conductance switching in polymer/electrolyte junctions
View Patent ↗A non-volatile memory device including at least a first electrode and a second electrode provided on a substrate, the first and second electrodes being separated from each other; an organic semiconductive polymer electrically connecting the first and second electrodes; an electrolyte in contact with the organic semiconductive polymer; and a third electrode that is not in contact with the first electrode, the second electrode, and the organic semiconductive polymer; wherein the organic semiconductive polymer has a first redox state in which it exhibits a first conductivity, and a second redox state in which it exhibits a second conductivity.
1. A three-terminal non-volatile memory device, comprising:
at least a first electrode and a second electrode provided on a substrate, the first and second electrodes being in contact with an organic semi-conductive polymer and separated from each other such that, the first electrode and second electrode electronically determine a first redox state, a second redox state, or a third redox state of the organic semiconductive polymer;
an active layer comprising the organic semiconductive polymer electrically connecting the first and second electrodes;
an electrolyte layer in contact with the active layer, wherein the active layer and the electrolyte are two separate layers; and
a third electrode that is not in contact with the first electrode, the second electrode, and the organic semiconductive polymer; wherein
the organic semiconductive polymer has the first redox state in which the organic semiconductive polymer exhibits conductivity in a neutral state of 10 −8 S/cm to 10 −3 S/cm at room temperature, the second redox state in which the organic semiconductive polymer exhibits conductivity greater than 0.001 S/cm to 10 S/cm at room temperature, and the third redox state in which the organic semiconductive polymer exhibits conductivity less than 0.001 S/cm or less than 10 S/cm at room temperature, wherein a “read” circuit does not pass through the electrolyte, and a write/erase” circuit passes current through the electrolyte, further wherein the organic semiconductive polymer contains mobile ions.
2. The three-terminal non-volatile memory device according to claim 1 , wherein the third electrode is in contact with the electrolyte.
3. The three-terminal non-volatile memory device according to claim 1 , wherein the first conductivity is greater than about 0.001 S/cm at room temperature, and wherein the second conductivity is at least 10 times less than the first conductivity.
4. The three-terminal non-volatile memory device according to claim 1 , wherein the second conductivity is less than about 0.1 S/cm at room temperature, and wherein the first conductivity is at least 10 times higher than the second conductivity.
5. The three-terminal non-volatile memory device according to claim 1 , wherein a ratio of the first conductivity to the second conductivity is greater than about 10.
6. The three-terminal non-volatile memory device according to claim 1 , wherein a ratio of the first conductivity to the second conductivity is in the range of from about 10 to about 10 10 .
7. The three-terminal non-volatile memory device according to claim 1 , wherein the electrolyte comprises mobile ions.
8. The three-terminal non-volatile memory device according to claim 1 , wherein the mobile ions are selected from the group consisting of positive ions, negative ions, metal ions, hydroxyl ions, and hydrogen ions.
9. The three-terminal non-volatile memory device according to claim 1 , wherein the first and second electrodes are formed substantially parallel with each other.
10. The three-terminal non-volatile memory device according to claim 1 , wherein the organic semiconductive polymer further comprises a dopant substance.
11. The three-terminal non-volatile memory device according to claim 10 , wherein the dopant substance is selected from the group consisting of iodine, alkali metals, Na, K, alkaline earth metals, Ca, precious metals, metal oxide, Fe 2 O 3 , Al 2 O 3 , ZnO, and metal salts.
12. The three-terminal non-volatile memory device according to claim 1 , wherein said electrolyte layer is a solid electrolyte.
13. The three-terminal non-volatile memory device according to claim 10 , wherein the solid electrolyte contains an ion conductive polymer and an electrolyte salt.
14. The three-terminal non-volatile memory device according to claim 1 , wherein organic semiconductive polymer is selected from the group consisting of polythiophene, polypyrrole, polyanniline, and polyfluorene.
15. The three-terminal non-volatile memory device according to claim 1 , wherein the device further comprises a complementary redox agent.
16. The three-terminal nonvolatile memory device according to claim 15 , wherein the device comprises a layer comprising a complementary redox agent, wherein the layer is in contact with the third electrode and is separated from the organic semiconductor polymer layer by the electrolyte layer.
17. The three-terminal non-volatile memory device according to claim 1 , wherein the organic semiconductive polymer is switched to the first redox state via an oxidation/reduction reaction.
18. The three-terminal non-volatile memory device according to claim 17 , wherein the first redox state of the organic semiconductive polymer is switched to the second redox state of the organic semiconductive polymer via an oxidation/reduction reaction.
19. The three-terminal non-volatile memory device according to claim 17 , wherein the oxidation/reduction takes place at the surfaces of the first electrode and the second electrode; and the device further comprises complementary oxidation/reduction, relative to the first and second electrodes, at the surface of the third electrode.
20. The three-terminal non-volatile memory device according to claim 1 , wherein the first electrode and second electrode electronically determine the first redox state or the second redox state of the organic semiconductive polymer by providing an electronic charge to the semiconductive polymer.
21. The three-terminal non-volatile memory device according to claim 1 , wherein the first electrode and second electrode electronically determine the first redox state or the second redox state of the organic semiconductive polymer by sensing an electronic charge of the semiconductive polymer.
22. A system comprising:
a memory: and
a memory controller configured to control the execution of programming and erase operations within the memory, wherein the memory comprises a three-terminal non-volatile memory device, the three-terminal non-volatile memory device including:
at least a first electrode and a second electrode provided on a substrate, the first and second electrodes being in contact with an organic semiconductive polymer and separated from each other such that, the first electrode and second electrode electronically determine a first redox state, a second redox state, or a third redox state of the organic semiconductive polymer;
an active layer comprising the organic semiconductive polymer electrically connecting the first and second electrodes;
an electrolyte layer in contact with the active, wherein the active layer and the electrolyte are two separate layers; and
a third electrode that is not in contact with the first electrode, the second electrode, and the organic semiconductive polymer; wherein
the organic semiconductive polymer has the first redox state in which the organic semiconductive polymer exhibits a first conductivity in a neutral state of 10 −8 S/cm to 10 −3 S/cm at room temperature, the second redox state in which the organic semiconductive polymer exhibits conductivity greater than 0.001 S/cm to 10 S/cm at room temperature, and the third redox state in which the organic semiconductive polymer exhibits conductivity less than about 0.001 S/cm or less than 10 S/cm, at room temperature, wherein a “read” circuit does not pass through the electrolyte, and a write/erase” circuit passes current through the electrolyte, further wherein the organic semiconductive polymer contains mobile ions.