Wavelength Conversion Photovoltaics

• US 20100206359A1
• Filed: 02/19/2009
• Published: 08/19/2010
• 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.
• Granted Patent: US 8,759,666 B2
• Time in Patent Office: Days
• US Class Current: 136/247
• 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, the PVD is configured to generate charge carriers from incident photons; and

an electric field generator coupled to apply an electric field to the PVD, a strength of the electric field being 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 enabling the PVD to generate emitted photons being radiated as an electromagnetic wave.

2. The apparatus of claim 1 further comprising:

a rectifying antenna operable to generate a direct current from the emitted photons.

3. The apparatus of claim 1, further comprising:

the electric field generator includes a pair of electrodes operable to provide a bias voltage, the bias voltage being able to control a configurable wavelength of the emitted photons, the QD array structure being disposed between the pair of electrodes.

4. The apparatus of claim 1, further comprising the transition of a charge carrier from one discrete energy state to an adjacent discrete energy state generates an emitted photon.

5. The apparatus of claim 1, further comprising energy in the charge carriers is harvested as the emitted photons before the charge carriers are captured by an electrode of the electric field generator.

6. The apparatus of claim 1, further comprising the QD array structure includes a plurality of quantum dots having a configurable diameter, the plurality of quantum dots being arranged in a sheet layer having a configurable thickness and a configurable length.

7. The apparatus of claim 1, further comprising the QD array structure is embedded in a polymer composite.

8. The apparatus of claim 1, further comprising the incident photons have a wavelength within a configurable range.

9. The apparatus of claim 8, further comprising the configurable range is between approximately 8 microns and approximately 40 microns.

10. The apparatus of claim 1, further comprising the electromagnetic wave has a configurable frequency.

11. The apparatus of claim 10, further comprising the configurable frequency is tunable in dependence of 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, and a length of the sheet, and a voltage of the electric field.

12. The apparatus of claim 10, further comprising the configurable frequency is within a radio frequency range from 10 gigahertz to approximately 1 terahertz.

13. The apparatus of claim 10, further comprising 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 gap at the configurable frequency.

14. The apparatus of claim 13, further comprising the phonon band structure is configurable to suppress the transition that causes the vibrations instead of the emitted photons.

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

16. The apparatus of claim 1, further comprising a number of the emitted photons are greater than a number of the incident photons by a factor of at least 2.

17. The apparatus of claim 1, further comprising an airship equipped with the apparatus.

18. 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 an electric field across the QD array structure, a strength of the electric field being sufficient 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; and

generating emitted photons caused by the transition of the charge carriers through the plurality of discrete energy states, the emitted photons being radiated as an electromagnetic wave.

19. The method of claim 18, further comprising:

harvesting the energy of the charge carriers before the charge carriers are captured by an electrode causing the electric field.

20. The method of claim 18, further comprising:

rectifying the electromagnetic wave to generate a direct current power output.

21. The method of claim 18, further comprising the incident photons are generated by heat sources having a temperature below 600 degrees Celsius.

22. The method of claim 18, further comprising a number of the emitted photons are greater than a number of the incident photons by a factor of at least 2×

, a wavelength of the incident photons being different than a wavelength of the emitted photons.