High energy storage capacitor by embedding tunneling nano-structures
In an All-Electron Battery (AEB), inclusions embedded in an active region between two electrodes of a capacitor provide enhanced energy storage. Electrons can tunnel to/from and/or between the inclusions, thereby increasing the charge storage density relative to a conventional capacitor. One or more barrier layers is present in an AEB to block DC current flow through the device. The AEB effect can be enhanced by using multi-layer active regions having inclusion layers with the inclusions separated by spacer layers that don't have the inclusions. The use of cylindrical geometry or wrap around electrodes and/or barrier layers in a planar geometry can enhance the basic AEB effect. Other physical effects that can be employed in connection with the AEB effect are excited state energy storage, and formation of a Bose-Einstein condensate (BEC).
1. A solid-state energy storage device comprising:
a first electrode;
a second electrode;
one or more active layers and one or more tunneling barrier layers sandwiched between the first electrode and the second electrode;
wherein the active layers comprise inclusions embedded within a solid active layer matrix, and wherein electrons can flow to or from the inclusions by tunneling through the active layer matrix;
wherein the tunneling barrier layers substantially prevent electron tunneling across the tunneling barrier layers and also substantially block all other direct current flow;
wherein the device is capable of storing energy by establishing a charge separation with the inclusions, and wherein the device is capable of providing energy by using the charge separation as an energy source; and
wherein the energy storage device is configured to provide electrostatic energy storage.
2. The device of claim 1 , wherein the device is a two-terminal device having only the first and second electrodes as external terminals.
3. The device of claim 1 , wherein the first and second electrodes each have a geometrical area of 1 μm 2 or greater.
4. The device of claim 1 , wherein the charge separation between the inclusions is established by application of a voltage of 5V or more between the first and second electrodes.
5. The device of claim 1 , wherein a volume averaged charge separation density of the device when the charge separation is present is 10 −4 e − /nm 3 or greater.
6. The device of claim 1 , wherein the inclusions are selected from the group consisting of: quantum well, quantum wire, quantum dot, and bulk material.
7. The device of claim 1 , wherein the inclusions are arranged according to size to provide a smooth work function gradient of the inclusions.
8. The device of claim 1 , wherein a first of the inclusions is surrounded by several others of the inclusions each having a smaller size than the first inclusion.
9. The device of claim 1 , wherein a first of the inclusions is surrounded by several others of the inclusions each having a larger size than the first inclusion.
10. The device of claim 1 , wherein a selected one of the active layers is adjacent to the first electrode or to the second electrode, and wherein electrons can tunnel from inclusions in the selected active layer to the adjacent electrode.
11. The device of claim 1 , wherein at least one of the active layers has inclusions which are spaced apart such that electrons can tunnel between inclusions.
12. The device of claim 1 , wherein at least one of the active layers comprises a multilayer structure having alternating spacer and inclusion layers, wherein the inclusion layers include the inclusions, wherein the spacer layers substantially do not include the inclusions, and wherein electrons can flow between the inclusion layers by tunneling through the spacer layers.
13. The device of claim 12 , wherein the inclusion layers comprise different materials having different work functions, and wherein the inclusion layers are disposed to form a Fermi level gradient.
14. The device of claim 12 , wherein the inclusion layers comprise a material having an electron affinity that is lower than an electron affinity of the spacer layers.
15. The device of claim 1 , wherein at least one of the active layers comprises a first inclusion layer and a second inclusion layer separated by a spacer layer, wherein the inclusion layers include the inclusions, wherein the spacer layers substantially do not include the inclusions, and wherein the inclusion layers are disposed sufficiently close to each other that electrons in the first inclusion layer of a selected active layer and holes in the second inclusion layer of the selected active layer can form excitons.
16. The device of claim 15 , wherein the inclusions in the first inclusion layer are selected from the group consisting of quantum wells, quantum wires, and quantum dots, and wherein the inclusions in the second inclusion layer are selected from the group consisting of quantum wells, quantum wires, and quantum dots.
17. The device of claim 15 , wherein the device is capable of forming a Bose-Einstein condensate of the excitons.
18. The device of claim 1 , wherein at least one of the inclusions has two or more bound electron states having different binding energy, wherein a ground state is the bound electron state having the least energy, and wherein bound electron states other than the ground state are referred to as excited states.
19. The device of claim 18 , wherein the device is capable of storing energy by charge transfer to at least one of the excited states.
20. The device of claim 19 , wherein energy can be provided by the device by transferring charge from excited states before transferring charge from corresponding ground states.