Optical downshifting layer

Patent metadata

Field	Value
Publication number	US-10840403-B2
Application number	US-201715712091-A
Country	US
Kind code	B2
Filing date	Sep 21, 2017
Priority date	Jul 14, 2009
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

The light conversion efficiency of a solar cell (10) is enhanced by using an optical downshifting layer (30) in cooperation with a photovoltaic material (22). The optical downshifting layer converts photons (50) having wavelengths in a supplemental light absorption spectrum into photons (52) having a wavelength in the primary light absorption spectrum of the photovoltaic material. The cost effectiveness and efficiency of solar cells platforms (20) can be increased by relaxing the range of the primary light absorption spectrum of the photovoltaic material. The optical downshifting layer can be applied as a low cost solution processed film composed of highly absorbing and emissive quantum dot heterostructure nanomaterial embedded in an inert matrix to improve the short wavelength response of the photovoltaic material. The enhanced efficiency provided by the optical downshifting layer permits advantageous modifications to the solar cell platform that enhances its efficiency as well.

First claim

The invention claimed is:

1. An optical downshifting layer, comprising:
a plurality of individually encapsulated non-spherical nanocrystals, each comprising a quantum dot heterostructure having a quantum dot core surrounded by a rod-shaped shell and individually encapsulated in a silica encapsulating material, the plurality of individually encapsulated non-spherical nanocrystals absorbing incident photons in a first wavelength range of the electromagnetic spectrum and emitting photons in a second wavelength range of the electromagnetic spectrum shown in a peak emission, such that the optical downshifting layer transforms the incident photons in the first wavelength range into photons in the second wavelength range of the electromagnetic spectrum,
wherein the plurality of individually encapsulated non-spherical nanocrystals exhibit an absorption onset at a wavelength of 600 nm with a range of 50 nm, and
wherein the peak emission is downshifted by 50 nm to 200 nm compared to the absorption onset.

2. The optical downshifting layer of claim 1 , in which the plurality of individually encapsulated non-spherical nanocrystals comprise quantum dot heterostructures each having a shape resembling a nanorod.

3. The optical downshifting layer of claim 1 , in which the plurality of individually encapsulated non-spherical nanocrystals comprise quantum dot heterostructures having a CdSe quantum dot core and a rod-shaped CdS shell.

4. The optical downshifting layer of claim 3 , in which the optical downshifting layer includes more than one type of individually encapsulated non-spherical quantum dot heterostructure.

5. The optical downshifting layer of claim 3 , in which at least some of the plurality of individually encapsulated non-spherical nanocrystals have a quantum dot core surrounded by more than one shell.

6. The optical downshifting layer of claim 1 , wherein the plurality of individually encapsulated non-spherical nanocrystals absorbing incident photons in the first wavelength range of the electromagnetic spectrum comprise non-spherical nanocrystals absorbing incident photons in a wavelength range of 0.2 to 0.6 microns.

7. The optical downshifting layer of claim 1 , wherein the first wavelength range of the electromagnetic spectrum is substantially outside of the second wavelength range of the electromagnetic spectrum.

8. The optical downshifting layer of claim 1 , wherein a majority of the first wavelength range of the electromagnetic spectrum is outside of the second wavelength range of the electromagnetic spectrum.

9. The optical downshifting layer of claim 1 , wherein the first wavelength range of the electromagnetic spectrum is completely outside of the second wavelength range of the electromagnetic spectrum.

10. The optical downshifting layer of claim 1 , wherein the first wavelength range of the electromagnetic spectrum is separated from the second wavelength range of the electromagnetic spectrum such that the emitted photons in the second wavelength range of the electromagnetic spectrum are not substantially reabsorbed in the optical downshifting layer.

11. The optical downshifting layer of claim 1 , wherein the optical downshifting layer is transmissive to incident photons in the second wavelength range of the electromagnetic spectrum such that they pass through the optical downshifting layer.

12. The optical downshifting layer of claim 1 , wherein the plurality of individually encapsulated non-spherical nanocrystals are encapsulated in a polymer matrix material.

13. The optical downshifting layer of claim 1 , wherein the plurality of individually encapsulated non-spherical nanocrystals are homogeneously dispersed in a matrix media.

14. The optical downshifting layer of claim 1 , wherein each of the plurality of individually encapsulated non-spherical nanocrystals is encapsulated in a silica sphere.

15. An optical downshifting layer, comprising:
a plurality of individually encapsulated non-spherical nanocrystals, each comprising a quantum dot heterostructure having a quantum dot core surrounded by a rod-shaped shell and individually encapsulated in a silica encapsulating material, wherein at least some of the plurality of individually encapsulated non-spherical nanocrystals have a quantum dot core surrounded by more than one shell, the plurality of individually encapsulated non-spherical nanocrystals absorbing incident photons in a first wavelength range of the electromagnetic spectrum, and emitting photons in a second wavelength range of the electromagnetic spectrum shown in a peak emission, such that the optical downshifting layer transforms the incident photons in the first wavelength range into photons in the second wavelength range of the electromagnetic spectrum,
wherein the plurality of individually encapsulated non-spherical nanocrystals exhibit an absorption onset at a wavelength of 600 nm with a range of 50 nm, and
wherein the peak emission is downshifted by 50 nm to 200 nm compared to the absorption onset.

16. An optical downshifting layer, comprising:
a plurality of individually encapsulated non-spherical nanocrystals, each comprising a quantum dot heterostructure having a CdSe quantum dot core surrounded by a rod-shaped CdS shell and individually encapsulated in a silica encapsulating material;
the plurality of individually encapsulated non-spherical nanocrystals absorbing incident photons in a first wavelength range of the electromagnetic spectrum shorter than or equal to 500 nm, and emitting photons in a second wavelength range of the electromagnetic spectrum, from 550 nm to 700, such that the optical downshifting layer transforms the incident photons in the first wavelength range into photons in the second wavelength range of the electromagnetic spectrum.

Assignees

• Pacific Light Tech Corp
• Osram Opto Semiconductors Gmbh

Inventors

• Kurtin Juanita N
• Hughes Steven M
• Mayer Alex C
• Park Oun Ho
• Masson Georgeta

Classifications

• Y02E10/52

  PV systems with concentrators · CPC title

• H10F77/45 Primary

  Wavelength conversion means, e.g. by using luminescent material, fluorescent concentrators or up-conversion arrangements · CPC title

• Y02E10/542

  Dye sensitized solar cells · CPC title

• C09K11/02

  Use of particular materials as binders, particle coatings or suspension media therefor · CPC title

• C09K11/565

  with zinc cadmium · CPC title