US4816082A
Expired / Lapsed
US
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Thin film solar cell including a spatially modulated intrinsic layer
Assignee: United Solar Systems Corp
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Filing: 1987-08-19
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Granted: 1989-03-28
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Expires: 2007-08-19
Abstract
Abstract One or more thin film solar cells in which the intrinsic layer of substantially amorphous semiconductor alloy material thereof includes at least a first band gap portion and a narrower band gap portion. The band gap of the intrinsic layer is spatially graded through a portion of the bulk thickness, said graded portion including a region removed from the intrinsic layer-dopant layer interfaces. The band gap of the intrinsic layer is always less than the band gap of the doped layers. The gradation of the intrinsic layer is effected such that the open circuit voltage and/or the fill factor of the one or plural solar cell structure is enhanced.
Inventors
- 👤 Subhendu Guha
- 👤 Chi-Chung Yang
- 👤 Stanford R. Ovshinsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:05
CPC Classifications
H; H10; H10F; H10F10/00; H10F10/10; H10F10/17; H10F10/172; B; B22; B22F; B22F9/00; B22F9/02; B22F9/023; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/047; H01F1/053; H01F1/055; H01F1/057; H01F1/0571; H01F1/0573; H10F10/13; H10F71/00; H10F71/10; H10F71/103; H10F71/1035; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y02E10/548; Y02P; Y02P70/00; Y02P70/50
Claims Analysis
Total Claims: 47
Claim 1
Independent Claim
150 words
A solar cell including at least one layer of thin film substantially amorphous intrinsic semiconductor alloy material; said intrinsic layer characterized by at least a first portion of the thickness thereof having a bandgap and a second portion of the thickness thereof having a second bandgap narrower than the first bandgap portion; said intrinsic layer sandwiched between oppositely doped layers of semiconductor alloy material; the bandgap of all portions of the intrinsic layer not contiguous to the intrinsic layer-dopant layer interfaces being less than the bandgap of the dopant layers; the improvement comprising, in combination: at least one band gap modifying element introduced into at least a substantial portion of the bulk thickness of the intrinsic layer so as to spatially grade the bandgap of said intrinsic layer over a substantial portion of the bulk thickness thereof, said graded portion including a region removed from the intrinsic layer-dopant layer interfaces.
Claim 2
Dependent Claim
150 words
A solar cell including at least one layer of thin film substantially amorphous intrinsic semiconductor alloy material; said intrinsic layer characterized by at least a first portion of the thickness thereof having a bandgap and a second portion of the thickness thereof having a second bandgap narrower than the first bandgap portion; said intrinsic layer sandwiched between oppositely doped layers of semiconductor alloy material; the bandgap of all portions of the intrinsic layer not contiguous to the intrinsic layer-dopant layer interfaces being less than the bandgap of the dopant layers; the improvement comprising, in combination: at least one band gap modifying element introduced into at least a substantial portion of the bulk thickness of the intrinsic layer so as to spatially grade the bandgap of said intrinsic layer over a substantial portion of the bulk thickness thereof, said graded portion including a region removed from the intrinsic layer-dopant layer interfaces.
Claim 3
Dependent Claim
34 words
A solar cell as in claim 1, wherein germanium is the band gap modifying element and a substantial portion of the bulk of the intrinsic layer is fabricated from a silicon germanium alloy material.
Claim 4
Dependent Claim
31 words
A solar cell as in claim 2, wherein the percentage of germanium incorporated into said silicon germanium alloy varies throughout a substantial portion of the bulk thickness of the intrinsic layer.
Claim 5
Dependent Claim
32 words
A solar cell as in claim 3, wherein the percentage of germanium incorporated into said silicon germanium alloy is graded through a substantial portion of the bulk thickness of the intrinsic layer.
Claim 6
Dependent Claim
41 words
A solar cell as in claim 4, wherein the percentage of germanium incorporated into said intrinsic layer is graded from a minimum adjacent each of the interfaces thereof with the doped layers to a maximum interiorly of the bulk thickness thereof.
Claim 7
Dependent Claim
30 words
A solar cell as in claim 5, wherein the grading of said germanium incorporated into said silicon germanium layer is maintained at said maximum for at least 500 angstroms thickness.
Claim 8
Dependent Claim
23 words
A solar cell as in claim 5, wherein the grading of said germanium incorporated into said silicon germanium layer reaches a sharp minimum.
Claim 9
Dependent Claim
29 words
A solar cell as in claim 5, wherein said intrinsic layer of silicon germanium alloy material includes a substantially germanium-free region at the interfaces thereof with the doped layers.
Claim 10
Dependent Claim
27 words
A solar cell as in claim 9, wherein said intrinsic layer further includes a band gap widening element incorporated adjacent the interfaces thereof with said doped layers.
Claim 11
Dependent Claim
27 words
A solar cell as in claim 9, wherein said band gap widening element is selected from the group consisting essentially of hydrogen, carbon, nitrogen, and mixtures thereof.
Claim 12
Dependent Claim
48 words
A solar cell as in claim 10, wherein the percentage incorporation of the band gap widening element is graded from a maximum at the interfaces of the intrinsic layer with the doped layers to a minimum adjacent to, but interior of, the bulk thickness of the intrinsic layer.
Claim 13
Dependent Claim
66 words
A solar cell as in claim 11, wherein the band gap of the intrinsic layer is substantially continuously graded from a widest band gap portion at each of the interfaces thereof with the oppositely disposed doped layers to a minimum bandgap portion adjacent a central region interiorly of the bulk thickness of the intrinsic layer, said central region having a band gap of approximately 1.2-1.6 eV.
Claim 14
Dependent Claim
35 words
A solar cell as in claim 4, wherein the band gap of said intrinsic layer of silicon germanium alloy material is graded to about a minimum of 1.2-1.6 eV interiorly of the bulk thickness thereof.
Claim 15
Dependent Claim
35 words
A solar cell as in claim 4, wherein the band gap of said intrinsic layer of silicon germanium alloy material is graded to about a minimum of 1.4-1.5 eV interiorly of the bulk thickness thereof.
Claim 16
Dependent Claim
22 words
A solar cell as in claim 4, wherein the light incident doped layer is fabricated as a p-type microcrystalline silicon alloy material.
Claim 17
Dependent Claim
30 words
A solar cell as in claim 15, wherein said p-type layer further includes a band gap widening element selected from the group consisting essentially of carbon, nitrogen, and combinations thereof.
Claim 18
Dependent Claim
26 words
A solar cell as in claim 15, wherein the doped layer opposite said p-type layer is fabricated as an n-type microcrystalline layer of silicon alloy material.
Claim 19
Dependent Claim
30 words
A solar cell as in claim 17, wherein said n-type layer further includes a band gap widening element selected from the group consisting essentially of carbon, nitrogen, and combinations thereof.
Claim 20
Dependent Claim
74 words
A solar cell as in claim 4, wherein the graded incorporation of germanium into said intrinsic layer is more rapid from the intrinsic layer interface with the light incident doped layer to the region of maximum germanium incorporation interiorly of the bulk thickness thereof as compared to the graded incorporation of germanium from the intrinsic layer interface with the doped layer opposite the light incident doped layer to said region of maximum germanium incorporation.
Claim 21
Dependent Claim
21 words
A solar cell as in claim 19, wherein said region of maximum germanium incorporation remains constant for at least 500 angstroms.
Claim 22
Dependent Claim
31 words
A solar cell as in claim 4, wherein boron is incorporated into the silicon germanium alloy material of said intrinsic layer so as to improve the collection of photogenerated charge carriers.
Claim 23
Dependent Claim
26 words
A solar cell as in claim 21, wherein the boron incorporated into said intrinsic layer is graded to compensate for the graded incorporation of germanium thereinto.
Claim 24
Dependent Claim
35 words
A solar cell as in claim 4, further including at least one additional solar cell disposed in optical and electrical series relation to said one solar cell so as to form a tandem photovoltaic structure.
Claim 25
Dependent Claim
113 words
A solar cell as in claim 23, wherein at least one of the at least one additional solar cell includes an intrinsic layer of thin film substantially amorphous semiconductor alloy material sandwiched between oppositely doped layers of semiconductor alloy material, said additional intrinsic layer characterized by at least a first portion of the thickness thereof having a band gap and a second portion of the thickness thereof having a band gap narrower than the first band gap; the band gap of the intrinsic layer of said additional cell being spatially graded throughout a substantial portion of the bulk thickness thereof, said graded portion including a region removed from the intrinsic layer-dopant layer interfaces.
Claim 26
Dependent Claim
42 words
A solar cell as in claim 24, wherein the narrower band gap semiconductor alloy material of the intrinsic layer of the additional solar cell differs from the narrower band gap semiconductor alloy material of the intrinsic layer of said one solar cell.
Claim 27
Dependent Claim
41 words
A solar cell as in claim 25, wherein the band gap and thickness of the intrinsic layers of the one solar cell and the at least one additional solar cell are such that the current photogenerated in each is substantially matched.
Claim 28
Dependent Claim
41 words
A solar cell as in claim 26, wherein the light incident doped layer of each cell is fabricated from p-type microcrystalline semiconductor alloy material and the oppositely disposed doped layer of each cell is fabricated from n-type microcrystalline semiconductor alloy material.
Claim 29
Dependent Claim
39 words
A solar cell as in claim 27, further including a dual layered back reflector operatively disposed below the lowermost n-type layer; said dual layered back reflector fabricated from a conductive oxide uppermost layer and a highly reflective lowermost layer.
Claim 30
Dependent Claim
28 words
A solar cell as in claim 28, wherein the uppermost back reflector layer is fabricated from zinc oxide and the lowermost back reflector layer is fabricated from silver.
Claim 31
Dependent Claim
45 words
A solar cell as in claim 28, further including a buffer layer operatively disposed between at least one of the intrinsic layers of semiconductor alloy material and at least one of the light incident doped layers in each of the cells of the photovoltaic structure.
Claim 32
Dependent Claim
157 words
A solar cell, including at least one layer of thin film substantially amorphous intrinsic semiconductor alloy material; said intrinsic layer characterized by at least a first portion of the thickness thereof having a bandgap and a second portion of the thickness thereof having a bandgap narrower than the first bandgap portion; said intrinsic layer sandwiched between oppositely doped layers of semiconductor alloy material; the band gap of all portions of the intrinsic layer not contiguous to the intrinsic layer-dopant layer interfaces being less than the band gap of the dopant layers; the improvement comprising, in combination: at least one band gap modifying element introduced into at least a substantial portion of the bulk thickness of the intrinsic layer so as to spatially grade the band gap of the intrinsic layer from widest band gap portions adjacent each of the interfaces therof with the doped layers to a minimum band gap portion interiorly of the bulk thickness thereof.
Claim 33
Dependent Claim
157 words
A solar cell, including at least one layer of thin film substantially amorphous intrinsic semiconductor alloy material; said intrinsic layer characterized by at least a first portion of the thickness thereof having a bandgap and a second portion of the thickness thereof having a bandgap narrower than the first bandgap portion; said intrinsic layer sandwiched between oppositely doped layers of semiconductor alloy material; the band gap of all portions of the intrinsic layer not contiguous to the intrinsic layer-dopant layer interfaces being less than the band gap of the dopant layers; the improvement comprising, in combination: at least one band gap modifying element introduced into at least a substantial portion of the bulk thickness of the intrinsic layer so as to spatially grade the band gap of the intrinsic layer from widest band gap portions adjacent each of the interfaces therof with the doped layers to a minimum band gap portion interiorly of the bulk thickness thereof.
Claim 34
Dependent Claim
52 words
A solar cell as in claim 31, wherein at least a substantial portion of the bulk of the intrinsic layer is fabricated from a silicon germanium alloy material; the germanium content incorporated into said silicon germanium alloy material is graded throughout a substantial portion of the bulk thickness of the intrinsic layer.
Claim 35
Dependent Claim
40 words
A solar cell as in claim 32, wherein the germanium percentage incorporated into said intrinsic layer is graded from a minimum adjacent each of the interfaces thereof with the doped layers to a maximum interiorly of the bulk thickness thereof.
Claim 36
Dependent Claim
29 words
A solar cell as in claim 33, wherein said intrinsic layer of silicon germanium alloy material includes a substantially germanium-free region at the interfaces thereof with the doped layers.
Claim 37
Dependent Claim
43 words
A solar cell as in claim 34, wherein the light incident doped layer is fabricated from p-type microcrystalline silicon alloy material and said p-type layer includes a band gap widening element selected from the group consisting essentially of carbon, nitrogen, and combinations thereof.
Claim 38
Dependent Claim
46 words
A solar cell as in claim 35, wherein the doped layer opposite said p-type layer is fabricated from n-type microcrystalline silicon alloy material and said n-type layer further includes a band gap widening element selected from the group consisting essentially of carbon, nitrogen, and combinations thereof.
Claim 39
Dependent Claim
74 words
A solar cell as in claim 33, wherein the graded incorporation of germanium into said intrinsic layer is more rapid from the intrinsic layer interface with the light incident doped layer to the region of maximum germanium incorporation interiorly of the bulk thickness thereof as compared to the graded incorporation of germanium from the intrinsic layer interface with the doped layer opposite the light incident doped layer to said region of maximum germanium incorporation.
Claim 40
Dependent Claim
21 words
A solar cell as in claim 37, wherein said region of maximum germanium incorporation is constant for at least 500 angstroms.
Claim 41
Dependent Claim
32 words
A solar cell as in claim 33, wherein boron is gradually incorporated into the silicon germanium alloy material of said intrinsic layer so as to improve the collection of photogenerated charge carriers.
Claim 42
Dependent Claim
47 words
A solar cell as in claim 33, wherein said intrinsic layer further includes a band gap widening element incorporated adjacent the interfaces thereof with each of said doped layers; said band gap widening element selected from the group consisting essentially of hydrogen, carbon, nitrogen, and mixtures thereof.
Claim 43
Dependent Claim
55 words
A solar cell as in claim 40, wherein the bandgap of the intrinsic layer is substantially continuously graded from a widest band gap portion at each of the interfaces thereof with the oppositely disposed doped layers to a minimum band gap portion adjacent a central region interiorly of the bulk thickness of the intrinsic layer.
Claim 44
Dependent Claim
35 words
A solar cell as in claim 32, further including at least one additional solar cell disposed in optical and electrical series relation to said one solar cell so as to form a tandem photovoltaic structure.
Claim 45
Dependent Claim
98 words
A solar cell as in claim 42, wherein at least one of the at least one additional solar cell includes an intrinsic layer of thin film substantially amorphous semiconductor alloy material sandwiched between oppositely doped layers of semiconductor alloy material, said additional intrinsic layer characterized by at least a first portion of the thickness thereof having a bandgap and a second portion of the thickness thereof having a bandgap narrower than the first band gap; the band gap of the intrinsic layer of said additional cell being spatially graded throughout a substantial portion of the bulk thickness thereof.
Claim 46
Dependent Claim
34 words
A solar cell as in claim 43, wherein the narrower band gap semiconductor alloy material of the additional solar cell differs from the narrower band gap semiconductor alloy material of said one solar cell.
Claim 47
Dependent Claim
41 words
A solar cell as in claim 44, wherein the band gap and thickness of the intrinsic layers of the one solar cell and the at least one additional solar cell are such that the current photogenerated in each is substantially matched.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-03-27 | 1992-09-26 | 1993-03-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-03-27 | 1996-09-26 | 1997-03-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-03-27 | 2000-09-26 | 2001-03-28 | $7700.00 | Window Closed / Lapsed |