Broad spectrum solar cell
First Claim
Patent Images
1. A solar cell comprising:
- a first junction of In1−
xGaxN having a first bandgap; and
a second junction of In1−
xGaxN having different composition, wherein x is between approximately 0 and 1, electrically coupled to the first junction, the second junction having a bandgap lower than the first bandgap, where the relative bandgaps are adjusted to a desired range of the solar spectrum.
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Abstract
An alloy having a large band gap range is used in a multijunction solar cell to enhance utilization of the solar energy spectrum. In one embodiment, the alloy is In1−xGaxN having an energy bandgap range of approximately 0.7 eV to 3.4 eV, providing a good match to the solar energy spectrum. Multiple junctions having different bandgaps are stacked to form a solar cell. Each junction may have different bandgaps (realized by varying the alloy composition), and therefore be responsive to different parts of the spectrum. The junctions are stacked in such a manner that some bands of light pass through upper junctions to lower junctions that are responsive to such bands.
100 Citations
33 Claims
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1. A solar cell comprising:
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a first junction of In1−
xGaxN having a first bandgap; anda second junction of In1−
xGaxN having different composition, wherein x is between approximately 0 and 1, electrically coupled to the first junction, the second junction having a bandgap lower than the first bandgap, where the relative bandgaps are adjusted to a desired range of the solar spectrum. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A solar cell comprising:
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a first junction having a n-type and a p-type doped GaInN layer having a first bandgap within a solar radiation range; a second junction having a n-type and a p-type doped InN layer having a bandgap lower than the first bandgap within the solar radiation range; and a tunnel junction sandwiched between the first and second junctions. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A solar cell comprising:
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a first junction having a n and a p doped GaInN layer having a first bandgap; a second junction having a n and a p doped InN layer having a second bandgap lower than the first bandgap; a front contact coupled to the first junction; a back contact coupled to the second junction; a set of interior contacts, wherein the interior contacts are coupled to respective first and second junctions, and aligned to provide electrical contact there between when the first and second junctions are in a stacked relationship. - View Dependent Claims (17, 18)
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19. A multijunction solar cell comprising:
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multiple electrically coupled junctions in stacked relationship, the junctions having a n-type and a p-type doped GaInN layer; a bottom junction positioned beneath, and electrically coupled to the stack of multiple junctions, the bottom junction having a n-type and a p-type doped InN layer, wherein the bottom junction has an energy bandgap within a solar radiation range, and the energy bandgap of each successive junction of the multiple stacked junctions from the bottom layer increases such that a top layer junction has the highest energy bandgap within the solar radiation range. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. A method of forming a multijunction solar cell using a single alloy system, the method comprising:
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forming a first junction on top of a buffer layer supported by a substrate, wherein the first junction comprises In1−
xGaxN;forming a tunnel junction on top of the first junction; forming a second junction on top of the tunnel junction, wherein the second junction comprises In1−
xGaxN, wherein x for the second junction is larger than x for the first junction and maintains a junction energy bandgap within a solar radiation range, wherein x is between approximately 0 and 1;removing the buffer layer and the substrate layer; and forming contacts on the first junction and the second junction to form the solar cell. - View Dependent Claims (27, 28, 29)
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30. A method of forming a multijunction solar cell, the method comprising:
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forming multiple junctions on top of buffer layers supported by a substrate, wherein the multiple junctions comprises In1−
xGaxN wherein x is between approximately 0 and 1;removing the buffer layers and the substrate layers from each of the junctions; mechanically stacking the junctions such that a top of the stack is closest to a solar energy source, and wherein x decreases in each successive layer from the top and maintains a junction energy bandgap within a solar radiation range; and forming contacts on junctions to electrically connect each successive junction to adjacent junctions. - View Dependent Claims (31)
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32. A solar cell comprising:
a solar cell having multiple junctions formed of a single ternary alloy wherein the compositional percentage of the alloy is varied to produce multiple subcells of different bandgaps. - View Dependent Claims (33)
Specification