Technique for detecting a defect in a multi-junction solar cell

Patent metadata

Field	Value
Publication number	US-10199985-B2
Application number	US-201715434152-A
Country	US
Kind code	B2
Filing date	Feb 16, 2017
Priority date	Feb 16, 2016
Publication date	Feb 5, 2019
Grant date	Feb 5, 2019

Abstract

A method for detecting a defect in a multi-junction solar cell is presented. The multi-junction solar cell comprises at least two vertically stacked p-n junctions. The method comprises exciting a first p-n junction of the at least two vertically stacked p-n junctions by illuminating the solar cell with excitation light in a first excitation wavelength range, detecting photoluminescence light emitted by photoluminescence of the first p-n junction, and generating a spatially resolved first photoluminescence image of the photoluminescence light emitted by the first p-n junction. Further, a computer program product and an apparatus for detecting a defect in a multi-junction solar cell are presented.

First claim

The invention claimed is:

1. A method for detecting a defect in a multi-junction solar cell comprising at least two vertically stacked p-n junctions, the method comprising:
exciting a first p-n junction of the at least two vertically stacked p-n junctions by illuminating the solar cell with excitation light in a first excitation wavelength range at a first illumination intensity that is constant over time;
exciting a second p-n junction of the at least two vertically stacked p-n junctions by illuminating the solar cell with excitation light in a second excitation wavelength range at a second illumination intensity that changes over time;
detecting photoluminescence light emitted by photoluminescence of the first p-n junction; and
generating a plurality of spatially resolved photoluminescence image of the photoluminescence light emitted by the first p-n junction while the second illumination intensity is changed over time; and
observing the generated plurality of photoluminescence images for regions in which the intensity changes over time.

2. The method of claim 1 , further comprising:
observing the first image for spatial intensity variations.

3. The method of claim 2 , wherein
observing the first image for spatial intensity variations comprises observing the first image for exponential intensity variations.

4. A method for detecting a defect in a multi junction solar cell comprising at least two vertically stacked p-n junctions, the method comprising:
exciting a first p-n junction of the at least two vertically stacked p-n junctions by illuminating the solar cell with excitation light in a first excitation wavelength range;
exciting a second p-n junction of the at least two vertically stacked p-n junctions by illuminating the solar cell with excitation light in a second excitation wavelength range;
detecting photoluminescence light emitted by photoluminescence of the first p-n junction;
generating the a spatially resolved photoluminescence image of photoluminescence light emitted by photoluminescence of the first p-n junction under excitation of the first p-n junction at a first illumination intensity and under excitation of the second p-n junction at a second illumination intensity;
generating a second photoluminescence image of photoluminescence light emitted by photoluminescence of the first p-n junction under excitation of the first p-n junction at the first illumination intensity and under excitation of the second p-n junction at a third illumination intensity different from the second illumination intensity;
combining the first photoluminescence image and the second photoluminescence image to a third photoluminescence image by using a mathematical operation; and
observing the third photoluminescence image for spatial intensity variations.

5. The method of claim 4 , wherein the mathematical operation is a subtraction of intensity values of one of the first and second photoluminescence image from the other of the first and second photoluminescence image.

6. The method of claim 1 , wherein exciting the first p-n junction of the at least two vertically stacked p-n junctions by illuminating the solar cell with excitation light in a first excitation wavelength range is carried out at a first illumination intensity that is configured to create a photocurrent in the first p-n junction in a range of 1 to 100 mA/cm2.

7. The method of claim 6 , wherein the photocurrent created in the first p-n junction is in a range of 10 to 20 mA/cm2.

8. The method of claim 1 , wherein exciting the second p-n junction of the at least two vertically stacked p-n junctions by illuminating the solar cell with excitation light in a second excitation wavelength range is carried out at a second illumination intensity that is configured to create a photocurrent in the second p-n junction in a range of 1 to 100 mA/cm2.

9. The method of claim 8 , wherein the photocurrent created in the second p-n junction is in a range of 10 to 20 mA/cm2.

10. The method of claim 1 , wherein
a center wavelength of the photoluminescence light emitted by photoluminescence of the first p-n junction is not included in the first excitation wavelength range.

11. The method of claim 1 , wherein
a center wavelength of the photoluminescence light emitted by photoluminescence of the first p-n junction is not included in the first excitation wavelength range;
a center wavelength of the photoluminescence light emitted by photoluminescence of the first p-n junction is not included in the second excitation wavelength range; and
the first excitation wavelength range and the second excitation wavelength range do not overlap each other.

12. A computer program product stored on a computer-readable non-transitory storage device comprising program code portions for performing the steps of claim 1 when the computer program product is executed on a computing device.

13. An apparatus for detecting a defect in a multi-junction solar cell comprising at least two vertically stacked p-n junctions, the apparatus comprising:
a first illumination unit configured to excite a first p-n junction of the at least two vertically stacked p-n junctions by illuminating the solar cell with excitation light in a first excitation wavelength range at a first illumination intensity that is constant over time;
a second illumination unit configured to excite a second p-n junction of the at least two vertically stacked p-n junctions by illuminating the solar cell with excitation light in a second excitation wavelength range at a second illumination intensity that changes over time;
a detecting unit configured to detect photoluminescence light emitted by photoluminescence of the first p-n junction;
an image generating unit configured to generate a plurality of spatially resolved first photoluminescence image of the photoluminescence light emitted by the first p-n junction while the second illumination intensity is changed over time; and
an observation unit for observing the generated plurality of photoluminescence images for regions in which the intensity changes over time.

14. An apparatus for detecting a defect in a multi junction solar cell comprising at least two vertically stacked p-n junctions, the apparatus comprising:
a first illumination unit configured to excite a first p-n junction of the at least two vertically stacked p-n junctions by illuminating the solar cell with excitation light in a first excitation wavelength range;
a second illumination unit configured to excite a second p-n junction of the at least two vertically stacked p-n junctions by illuminating the solar cell with excitation light in a second excitation wavelength range;
a detecting unit configured to detect photoluminescence light emitted by photoluminescence of the first p-n junction; and
an image generating unit is configured to generate a spatially resolved first photoluminescence image of photoluminescence light emitted by photoluminescence of the first p-n junction under excitation of the first p-n junction at a first illumination intensity and under excitation of the second p-n junction at a second illumination intensity and to generate a second photoluminescence image of photoluminescence light emitted by photoluminescence of the first p-n junction under excitation of the first p-n junction at the first illumination intensity and under excitation of the second p-n junction at a third illumination intensity different from the second illumination intensity;
a combining unit configured to combine the first photoluminescence image and the second photoluminescence image to a third photoluminescence image by using a mathe

Assignees

• Airbus Ds Gmbh

Inventors

• Zimmermann Claus
• Nesswetter Helmut
• Rutzinger Martin

Classifications

• G01N21/6489

  Photoluminescence of semiconductors · CPC title

• G06T11/60

  Creating or editing images; Combining images with text · CPC title

• G01N21/8806

  Specially adapted optical and illumination features · CPC title

• H01L31/06

  Electricity · mapped topic

• H02S50/15 Primary

  using optical means, e.g. using electroluminescence · CPC title