Wide-bandgap, lattice-mismatched window layer for a solar conversion device
First Claim
1. A photovoltaic cell comprising:
- at least one subcell, at least one of said at least one subcells having an emitter layer, said emitter layer composed of a first material having a first material lattice constant; and
a lattice-mismatched window layer positioned directly adjacent to said emitter layer, wherein the lattice-mismatched window layer is composed of a second material having a second material lattice constant wherein said first material lattice constant and said second material lattice constant differ in material lattice constant values by at least greater than approximately 1.0%.
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Accused Products
Abstract
A photovoltaic cell or other optoelectronic device having a wide-bandgap semiconductor used in the window layer. This wider bandgap is achieved by using a semiconductor composition that is not lattice-matched to the cell layer directly beneath it and/or to the growth substrate. The wider bandgap of the window layer increases the transmission of short wavelength light into the emitter and base layers of the photovoltaic cell. This in turn increases the current generation in the photovoltaic cell. Additionally, the wider bandgap of the lattice mismatched window layer inhibits minority carrier injection and recombination in the window layer.
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Citations
24 Claims
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1. A photovoltaic cell comprising:
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at least one subcell, at least one of said at least one subcells having an emitter layer, said emitter layer composed of a first material having a first material lattice constant; and
a lattice-mismatched window layer positioned directly adjacent to said emitter layer, wherein the lattice-mismatched window layer is composed of a second material having a second material lattice constant wherein said first material lattice constant and said second material lattice constant differ in material lattice constant values by at least greater than approximately 1.0%. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A photovoltaic cell comprising:
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at least one subcell, at least one of said at least one subcells having an emitter layer and a base layer, said base layer composed of a first material having a first material lattice constant;
wherein said emitter layer is a heterojunction emitter layer composed of a second material, said second material having a second material lattice constant that is not equal to said first material lattice constant and wherein said first material lattice constant and said second material lattice constant differ in material lattice constant values by at least greater than approximately 1.0%. - View Dependent Claims (14, 15, 16)
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17. A photovoltaic cell comprising:
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at least one subcell, at least one of said at least one subcells having an emitter layer and a base layer and a BSF layer, said base layer composing a second material having a second lattice constant;
wherein said BSF layer is composed of a first material, said first material having a first material lattice constant that is not equal to said second material lattice constant and wherein said BSF layer is lattice mismatched by a material lattice constant value of at least greater than approximately 1.0% to said base layer. - View Dependent Claims (18)
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19. A photovoltiac cell comprising:
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at least one subcell, at least one of said at least one subcells having an emitter layer and a base layer, said base layer of said at least one subcell composed of a second material having a second material lattice constant, wherein at least one of said emitter layers is a lattice-mismatched heterojunction emitter layer composed of a first material, said first material having a first material lattice constant that is not equal to said second material lattice constant and wherein said first material lattice constant and said second material lattice constant differ in material lattice constant values by at least greater than approximately 1.0%.
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20. A photovoltiac cell comprising:
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at least one subcell, at least one of said at least one subcells having an emitter layer and a base layer; and
a lattice mismatched window layer positioned directly adjacent to said emitter layer, wherein said lattice mismatched window layer is composed of a first material, said first material having a first material lattice constant that is not equal to a second material lattice constant of a second material composing said emitter layer and is not equal to a third material lattice constant of a third material composing said base layer, wherein said first material lattice constant and said second material lattice constant differ in material lattice constant values by at least approximately 1.0% and wherein said first material lattice constant and said third material lattice constant differ in material lattice constant values by at least greater than approximately 1.0%.
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21. A method for increasing current generation in a photovoltaic cell or other optoelectronic device, the method comprising the steps of:
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providing at least one subcell layer, wherein at least one of said at least one subcell layers has an emitter layer; and
growing a lattice-mismatched window layer positioned directly adjacent to said emitter layer, wherein the lattice-mismatched window layer is composed of a first material, said first material having a first material lattice constant that is not equal to a second material lattice constant of a second material composing said emitter layer and wherein said first material lattice constant and said second material lattice constant differ in material lattice constant values by at least greater than approximately 1.0%. - View Dependent Claims (22, 23, 24)
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Specification