Wavelength conversion photovoltaics

• US 8,759,666 B2
• Filed: 02/19/2009
• Issued: 06/24/2014
• Est. Priority Date: 02/19/2009
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Evans, Matthew H.
• Primary Examiner(s): Michener, Jennifer
• Assistant Examiner(s): McConnell, Marla D
• Application Number:
  US12/388,699
• Publication Number:
  US 20100206359A1
• Time in Patent Office: 1,951 Days
• Field of Search: 136/243, 136/244, 136/246, 136/247, 136/248, 136/250, 136/253, 136/255, 136/257, 136/292
• US Class Current: 136/250
• CPC Class Codes: B64B 1/14 Outer covering
• CPC Class Codes: B64D 27/353 using solar cells
• CPC Class Codes: B64G 1/443 Photovoltaic cell arrays
• CPC Class Codes: H01L 31/04 adapted as photovoltaic [PV] conversion devices testing thereof during manufacture H01L22/00; testing thereof after manufacture H02S50/10
• CPC Class Codes: H01L 31/055 where light is absorbed and re-emitted at a different wavelength by the optical element directly associated or integrated with the PV cell, e.g. by using luminescent material, fluorescent concentrators or up-conversion arrangements
• CPC Class Codes: Y02E 10/52 PV systems with concentrators
• CPC Class Codes: Y02T 50/50 On board measures aiming to increase energy efficiency

Abstract

An apparatus includes a photovoltaic device (PVD) having a quantum dot (QD) array structure that is capable of performing wavelength conversion. The PVD is configured to generate charge carriers from incident photons. An electric field generator is operable to apply an electric field to the PVD. Strength of the electric field is sufficient to cause the charge carriers to transition through a plurality of discrete energy states formed within a corresponding one of a conductive band and a valence band of the QD array structure. The transition of the charge carriers through the plurality of discrete energy states enables the PVD to generate emitted photons being radiated as an electromagnetic wave. A frequency (and hence wavelength) of the emitted photons being radiated as the electromagnetic wave is tunable by configuring physical attributes of the QD array structure and controlling the electric field strength.

Claims

1. An apparatus comprising:

a photovoltaic device (PVD) including a quantum dot (QD) array structure, wherein the QD array structure is configured to generate charge carriers from incident photons; and

an electric field generator coupled to the QD array structure and configured to apply an electric field to the QD array structure, the electric field configured to cause the charge carriers to transition through a plurality of discrete energy states formed within a corresponding one of a conductive band and a valence band of the QD array structure, the transition of the charge carriers through the plurality of discrete energy states enabling the QD array structure to generate emitted photons at the conductive and valence bands as an electromagnetic wave having a specified frequency; and

a rectifying antenna operable to convert the electromagnetic wave having a frequency greater than 1 terahertz (THz) up to 10 THz into a direct current power output,

wherein;

the electric field generator comprises a first electrode and a second electrode, the first electrode and second electrode being operable to provide a bias voltage to control a configurable wavelength of the emitted photons,

the QD array structure being disposed between the first electrode and the second electrode, wherein the first electrode and the second electrode are on opposite sides of the QD array structure, and

the rectifying antenna is in direct physical contact with the first electrode.

2. The apparatus of claim 1, wherein the QD array structure is configured to generate the emitted photons based on a transition of a charge carrier from one discrete energy state to an adjacent discrete energy state.

3. The apparatus of claim 1, wherein the QD array structure is configured to generate the emitted photons based on energy harvested from the charge carriers before the charge carriers are captured by one or more of the first and second electrodes of the electric field generator.

4. The apparatus of claim 1, wherein the QD array structure comprises a plurality of quantum dots arranged in stacked sheet layers in a matrix structure.

5. The apparatus of claim 4, wherein the QD array structure is embedded in a polymer composite of the matrix structure.

6. The apparatus of claim 1, wherein the incident photons have a wavelength in a range of 8 microns to 40 microns.

7. The apparatus of claim 6, wherein the emitted photons have a wavelength in a range of 30 millimeters to 30 micrometers.

8. The apparatus of claim 1, wherein the specified frequency is based on at least one of a size of a quantum dot included in the QD array structure, a distance between adjacent quantum dots included in the QD array structure, a thickness of the QD array structure formed as a sheet layer, and a length of the sheet layer.

9. The apparatus of claim 1, wherein the specified frequency is in a range of 10 gigahertz to 1 terahertz.

10. The apparatus of claim 1, wherein the QD array structure vibrates in response to the incident photons, the vibrations being in accordance with a phonon band structure for the QD array structure, the phonon band structure including a frequency gap at the specified frequency.

11. The apparatus of claim 10, wherein the phonon band structure is configured to suppress the transition that causes the vibrations instead of harvesting energy for the emitted photons.

12. The apparatus of claim 1, wherein the incident photons are generated by heat sources having a temperature below 600 degrees Celsius.

13. The apparatus of claim 1, wherein a number of the emitted photons is greater than a number of the incident photons by a factor of at least 2.

14. The apparatus of claim 1, wherein the apparatus is equipped within an airship.

15. A method for harvesting energy from incident photons, the method comprising:

receiving the incident photons in a photovoltaic device (PVD) including a quantum dot (QD) array structure;

generating charge carriers in the PVD, the charge carriers being generated by harvesting the energy from the incident photons;

applying, by an electric field generator coupled to the QD array structure, an electric field across the QD array structure, the electric field being configured to cause the charge carriers to transition through a plurality of discrete energy states formed within a corresponding conductive band and a valence band of the QD array structure;

generating emitted photons from energy harvested from the charge carriers transitioning through the plurality of discrete energy states, the emitted photons being radiated as an electromagnetic wave having a specified frequency; and

rectifying, by a rectifying antenna, the electromagnetic wave having a frequency greater than 1 terahertz (THz) up to 10 THz to generate a direct current power output,

wherein;

the electric field generator comprises a first electrode and a second electrode, the first electrode and second electrode being operable to provide a bias voltage to control a configurable wavelength of the emitted photons,

the QD array structure being disposed between the first electrode and the second electrode, wherein the first electrode and the second electrode are on opposite sides of the QD array structure, and

the rectifying antenna is in direct physical contact with the first electrode.

16. The method of claim 15, further comprising:

harvesting the energy of the charge carriers before the charge carriers are captured by one or more of the first and second electrodes in the PVD causing the electric field.

17. The method of claim 15, wherein the incident photons originate from heat sources having a temperature below 600 degrees Celsius.

18. The method of claim 15, wherein a number of the emitted photons is greater than a number of the incident photons by a factor of at least two, and wherein the incident photons have a wavelength that is different from a wavelength of the emitted photons.