US4680422A
Expired / Lapsed
US
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Two-terminal, thin film, tandem solar cells
Assignee: Boeing Co
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Filing: 1985-10-30
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Granted: 1987-07-14
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Expires: 2005-10-30
Abstract
Abstract Tandem solar cells combine the energy-absorbing efficiencies of 1.7 eV CdSe/ZnTe heterojunctions with 1.0 eV I-III-VI2/II-VI heterojunctions in mechanically-stacked or monolithic cells. Lightweight, efficient tandem cells that are particularly suited to space applications due to their radiation hardness are constructed by judicious selection of the substrate, superstrate and semiconductor materials.
Inventors
- 👤 Billy J. Stanbery
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:02
CPC Classifications
H; H10; H10F; H10F10/00; H10F10/10; H10F10/16; H10F10/167; H10F10/161; H10F10/162; H10F10/19; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y02E10/541; Y02E10/543
Claims Analysis
Total Claims: 57
Claim 1
Independent Claim
83 words
A polycrystalline, tandem, photovoltaic transducer, comprising: (a) an upper cell having a bandgap of about 1.7 eV and comprising a heterojunction of n-type CdSe and p-type ZnTe, the junction being formed by depositing the ZnTe on the CdSe at low temperatures below about 350° C.; (b) a lower cell electrically connected to the upper cell, having a bandgap of about 1.0 eV, and comprising a thin film heterojunction between a graded ternary I-III-VI 2 semiconductor and a thin film II-VI semiconductor window layer.
Claim 2
Dependent Claim
83 words
A polycrystalline, tandem, photovoltaic transducer, comprising: (a) an upper cell having a bandgap of about 1.7 eV and comprising a heterojunction of n-type CdSe and p-type ZnTe, the junction being formed by depositing the ZnTe on the CdSe at low temperatures below about 350° C.; (b) a lower cell electrically connected to the upper cell, having a bandgap of about 1.0 eV, and comprising a thin film heterojunction between a graded ternary I-III-VI 2 semiconductor and a thin film II-VI semiconductor window layer.
Claim 3
Dependent Claim
21 words
The transducer of claim 1 wherein the upper cell includes an n + -type transparent conductive oxide layer contacting the CdSe.
Claim 4
Dependent Claim
16 words
The transducer of claim 2 wherein the oxide layer forms a contact for the upper cell.
Claim 5
Dependent Claim
14 words
The transducer of claim 3 wherein the oxide layer includes SnO 2 or ZnO.
Claim 6
Dependent Claim
13 words
The transducer of claim 4 wherein the oxide layer includes SnO 2 :F.
Claim 7
Dependent Claim
28 words
The transducer of claim 2 wherein the upper cell includes a substantially optically transparent superstrate, transparent in the range between about 400-1300 nm, bonded to the oxide layer.
Claim 8
Dependent Claim
15 words
The transducer of 6 wherein the lower cell semiconductors include a CuInSe 2 /(Cd,Zn)S heterojunction.
Claim 9
Dependent Claim
15 words
The transducer of 6 wherein the lower cell semiconductors include a CuInSe 2 /(Cd,Zn)S heterojunction.
Claim 10
Dependent Claim
19 words
The transducer of claim 7 wherein the lower cell includes a contact and a substrate bonded to the contact.
Claim 11
Dependent Claim
10 words
The transducer of claim 8 wherein the contact includes molybdenum.
Claim 12
Dependent Claim
16 words
The transducer of claim 9 wherein the substrate of the lower cell is a metal foil.
Claim 13
Dependent Claim
10 words
The transducer of claim 10 wherein the foil is titanium.
Claim 14
Dependent Claim
24 words
The transducer of claim 7 wherein the connection between the upper and lower cells is metalization between the ZnTe layer and the (Cd,Zn)S layer.
Claim 15
Dependent Claim
17 words
The transducer of claim 1 wherein the lower cell semiconductors include a CuInSe 2 /(Cd, Zn)S heterojunction.
Claim 16
Dependent Claim
27 words
The transducer of claim 13 wherein the lower cell is made according to one of the methods of Mickelsen and Chen described in U.S. Pat. No. 31,968.
Claim 17
Dependent Claim
27 words
The transducer of claim 13 wherein the lower cell is made according to one of the methods of Mickelsen and Chen described in U.S. Pat. No. 4,523,051.
Claim 18
Dependent Claim
24 words
The transducer of claim 13 wherein the lower cell includes a contact bonded to the CuInSe 2 and a substrate bonded to the contact.
Claim 19
Dependent Claim
10 words
The transducer of claim 16 wherein the contact includes molybdenum.
Claim 20
Dependent Claim
16 words
The transducer of claim 17 wherein the substrate of the lower cell is a metal foil.
Claim 21
Dependent Claim
26 words
The transducer of claim 1 wherein the lower cell includes a contact bonded to the I-III-VI 2 semiconductor layer and a substrate bonded to the contact.
Claim 22
Dependent Claim
16 words
The transducer of claim 19 wherein the substrate of the lower cell is a metal foil.
Claim 23
Dependent Claim
24 words
The transducer of claim 1 wherein the connection between upper and lower cells is metalization between the ZnTe layer and the II-VI semiconductor layer.
Claim 24
Dependent Claim
15 words
The transducer of claim 1 further comprising an adhesive between the upper and lower cells.
Claim 25
Dependent Claim
22 words
The transducer of claim 22 wherein the adhesive is selected from the group consisting of silicones, ethylvinyl acetates, epoxies, polyvinyldifluorides, and polyimides.
Claim 26
Dependent Claim
11 words
The transducer of claim 22 wherein the adhesive is an epoxy.
Claim 27
Dependent Claim
19 words
The transducer of claim 22 wherein the adhesive is substantially optically transparent in the range of about 700-1300 nm.
Claim 28
Dependent Claim
172 words
A polycrystalline, thin-film, tandem photovoltaic transducer, comprising: (a) an upper cell having a bandgap of about 1.7 eV and comprising: (i) a substantially optically transparent superstrate in the range of about 400-1300 nm; (ii) an n + conductive oxide layer deposited on the superstrate, the layer including either SnO 2 or ZnO and having a thickness of between about 2-10 micrometers; and (iii) a frontwall heterojunction comprising about a 3-5 micrometer layer of CdSe deposited on the oxide layer and about a 0.5-3 micrometer layer of ZnTe deposited on the CdSe at a temperature at or below about 350° C. to control and limit CdSe-ZnTe interdiffusion at the heterojunction; (b) a lower cell having a bandgap of about 1.0 eV and comprising: (i) a substrate; (ii) a molybdenum contact layer deposited on the substrate; and (iii) a graded CuInSe 2 /(Cd,Zn)S semiconductor heterojunction deposited on the contact layer; and (c) metalization connecting the upper and lower cells between the ZnTe layer of the upper cell and (Cd,Zn)S layer of the lower cell.
Claim 29
Dependent Claim
172 words
A polycrystalline, thin-film, tandem photovoltaic transducer, comprising: (a) an upper cell having a bandgap of about 1.7 eV and comprising: (i) a substantially optically transparent superstrate in the range of about 400-1300 nm; (ii) an n + conductive oxide layer deposited on the superstrate, the layer including either SnO 2 or ZnO and having a thickness of between about 2-10 micrometers; and (iii) a frontwall heterojunction comprising about a 3-5 micrometer layer of CdSe deposited on the oxide layer and about a 0.5-3 micrometer layer of ZnTe deposited on the CdSe at a temperature at or below about 350° C. to control and limit CdSe-ZnTe interdiffusion at the heterojunction; (b) a lower cell having a bandgap of about 1.0 eV and comprising: (i) a substrate; (ii) a molybdenum contact layer deposited on the substrate; and (iii) a graded CuInSe 2 /(Cd,Zn)S semiconductor heterojunction deposited on the contact layer; and (c) metalization connecting the upper and lower cells between the ZnTe layer of the upper cell and (Cd,Zn)S layer of the lower cell.
Claim 30
Dependent Claim
26 words
The transducer of claim 26 further comprising a substantially optically transparent adhesive in the range between about 700-1300 nm for bonding the upper and lower cells.
Claim 31
Dependent Claim
13 words
The transducer of claim 26 wherein the oxide layer includes SnO 2 :F.
Claim 32
Dependent Claim
28 words
The transducer of claim 26 wherein the lower cell is made according to one of the methods of Mickelsen and Chen described in U.S. Pat. No. Re. 31,968.
Claim 33
Dependent Claim
11 words
The transducer of claim 26 wherein the substrate is titanium foil.
Claim 34
Dependent Claim
13 words
The transducer of claim 30 wherein the superstrate is either glass or sapphire.
Claim 35
Dependent Claim
79 words
A polycrystalline, thin-film, tandem, photovoltaic transducer, especially adapted for terrestrial and space solar cell applications, comprising: (a) a polycrystalline p-ZnTe/n-CdSe/n + conductive oxide frontwall heterojunction drift field cell as the upper cell of the tandem; and (b) a thin-film, I-III-VI 2 /II-VI heterojunction as the lower cell of the tandem, the lower cell being characterized as without voids or copper nodules and having an energy conversion efficiency, when tested apart from the tandem, of a least about 8% AMO.
Claim 36
Dependent Claim
79 words
A polycrystalline, thin-film, tandem, photovoltaic transducer, especially adapted for terrestrial and space solar cell applications, comprising: (a) a polycrystalline p-ZnTe/n-CdSe/n + conductive oxide frontwall heterojunction drift field cell as the upper cell of the tandem; and (b) a thin-film, I-III-VI 2 /II-VI heterojunction as the lower cell of the tandem, the lower cell being characterized as without voids or copper nodules and having an energy conversion efficiency, when tested apart from the tandem, of a least about 8% AMO.
Claim 37
Dependent Claim
60 words
The transducer of claim 32, exhibiting superior radiation hardness characteristics, low weight, and high energy conversion efficiency, further comprising: (a) a substantially optically transparent sapphire superstrate for the upper cell; (b) a titanium metal foil substrate for the lower cell; (c) a molybdenum contact deposited over the foil beneath the heterojunction; and (d) a dielectric between the foil and contact.
Claim 38
Dependent Claim
15 words
The transducer of claim 33 wherein the lower cell heterojunction is graded CuInSe 2 /(Cd,Zn)S.
Claim 39
Dependent Claim
27 words
The transducer of claim 34 wherein the upper cell has a bandgap of about 1.7 eV and the lower cell has a bandgap of about 1.0 eV.
Claim 40
Dependent Claim
98 words
A monolithic, polycrystalline, tandem, photovoltaic transducer, comprising: (a) a lower cell comprising a I-III-VI 2 semiconductor photoactive layer having a bandgap of about 1.0 eV; (b) a graded interface connector deposited on the lower cell to provide a smooth lattice match transition between the lower cell and an upper cell of the tandem, the connector being degenerately doped in the regions away from the photoactive junctions; and (c) a polycrystalline n-type CdSe/n + , transparent conductive oxide cell deposited sequentially atop the connector to form the upper cell, the upper cell having a bandgap of about 1.7 eV.
Claim 41
Dependent Claim
98 words
A monolithic, polycrystalline, tandem, photovoltaic transducer, comprising: (a) a lower cell comprising a I-III-VI 2 semiconductor photoactive layer having a bandgap of about 1.0 eV; (b) a graded interface connector deposited on the lower cell to provide a smooth lattice match transition between the lower cell and an upper cell of the tandem, the connector being degenerately doped in the regions away from the photoactive junctions; and (c) a polycrystalline n-type CdSe/n + , transparent conductive oxide cell deposited sequentially atop the connector to form the upper cell, the upper cell having a bandgap of about 1.7 eV.
Claim 42
Dependent Claim
15 words
The transducer of claim 36 wherein the lower cell photoactive layer includes CuInSe 2 .
Claim 43
Dependent Claim
11 words
The transducer of claim 36 wherein the interface connector includes n-ZnSe/p-ZnTe.
Claim 44
Dependent Claim
21 words
The transducer of claim 36 wherein the lower cell includes a molybdenum contact deposited on a substrate below the photoactive layer.
Claim 45
Dependent Claim
24 words
The transducer of claim 39 wherein the substrate is a metal foil, and the cell further comprises a dielectric between the foil and contact.
Claim 46
Dependent Claim
10 words
The transducer of claim 40 wherein the foil is titanium.
Claim 47
Dependent Claim
16 words
The transducer of claim 36 further comprising an antireflection coating bonded to the transparent conductive oxide.
Claim 48
Dependent Claim
94 words
A monolithic, polycrystalline, tandem, photovoltaic transducer, comprising: (a) a metal foil substrate; (b) a molybdenum contact deposited over the substrate; (c) a p-CuInSe 2 layer having a bandgap of about 1.0 eV deposited on the contact; (d) a graded n-ZnSe/p-ZnTe interface connector deposited upon the p-CuInSe 2 layer, the interface layer being degenerately doped in the regions away from the photoactive junctions; (e) an n-CdSe layer having a bangap of about 1.7 eV deposited on the p-ZnTe of the interface layer; and (f) a transparent conductive oxide upper contact deposited on the n-CdSe layer.
Claim 49
Dependent Claim
94 words
A monolithic, polycrystalline, tandem, photovoltaic transducer, comprising: (a) a metal foil substrate; (b) a molybdenum contact deposited over the substrate; (c) a p-CuInSe 2 layer having a bandgap of about 1.0 eV deposited on the contact; (d) a graded n-ZnSe/p-ZnTe interface connector deposited upon the p-CuInSe 2 layer, the interface layer being degenerately doped in the regions away from the photoactive junctions; (e) an n-CdSe layer having a bangap of about 1.7 eV deposited on the p-ZnTe of the interface layer; and (f) a transparent conductive oxide upper contact deposited on the n-CdSe layer.
Claim 50
Dependent Claim
15 words
The transducer of claim 43 further comprising an antireflection coating bonded to the upper contact.
Claim 51
Independent Claim
187 words
A method of making a monolithic, polycrystalline, tandem, photovoltaic transducer, comprising the steps of: (a) applying a metallic base contact to a suitable substrate; (b) sequentially depositing a graded p-CuInSe 2 layer on the contact, the layer having two regions, a first region on the contact and a second region away from the contact atop the first region, the regions being formed by the simultaneous elemental evaporation of Cu, In, and Se, the region away from the contact being slightly copper deficient so as to form a moderately high resistivity, transient n-type layer; (c) depositing n-ZnSe on the n-type CuInSe 2 layer by low temperature CVD to avoid interdiffusion at the junction; (d) depositing p-ZnTe on the n-ZnSe by low temperature CVD to avoid interdiffusion at the junction, the n-ZnSe and p-ZnTe forming an interface transition between the lattice of the CuInSe 2 layer and an upper cell, and being degenerately doped in the regions away from the photoactive junctions; (e) depositing n-CdSe to form the upper cell on the p-ZnTe; and (f) depositing an upper contact of n + -type transparent conductive oxide on the n-CdSe.
Claim 52
Independent Claim
187 words
A method of making a monolithic, polycrystalline, tandem, photovoltaic transducer, comprising the steps of: (a) applying a metallic base contact to a suitable substrate; (b) sequentially depositing a graded p-CuInSe 2 layer on the contact, the layer having two regions, a first region on the contact and a second region away from the contact atop the first region, the regions being formed by the simultaneous elemental evaporation of Cu, In, and Se, the region away from the contact being slightly copper deficient so as to form a moderately high resistivity, transient n-type layer; (c) depositing n-ZnSe on the n-type CuInSe 2 layer by low temperature CVD to avoid interdiffusion at the junction; (d) depositing p-ZnTe on the n-ZnSe by low temperature CVD to avoid interdiffusion at the junction, the n-ZnSe and p-ZnTe forming an interface transition between the lattice of the CuInSe 2 layer and an upper cell, and being degenerately doped in the regions away from the photoactive junctions; (e) depositing n-CdSe to form the upper cell on the p-ZnTe; and (f) depositing an upper contact of n + -type transparent conductive oxide on the n-CdSe.
Claim 53
Dependent Claim
18 words
The method of claim 45 further comprising the step of applying an antireflection coating to the upper contact.
Claim 54
Dependent Claim
27 words
The method of claim 45 wherein the p-CuInSe 2 layer has a bandgap of about 1.0 eV and the n-CdSe has a bandgap of about 1.7 eV.
Claim 55
Independent Claim
169 words
A method for making a polycrystalline, tandem, photovoltaic transducer, comprising the steps of: (a) forming a lower cell by the steps of: (i) depositing a molybdenum contact over a metal foil substrate; (ii) depositing a graded p-n type CuInSe 2 layer on the contact by simultaneous elemental evaporation, the layer having a portion removed from the contact that is copper-deficient, and having a bandgap of about 1.0 eV; (iii) depositing an n-(Cd,Zn)S layer atop the CuInSe 2 layer; (b) forming an upper cell by the steps of: (i) depositing an n + -type transparent conductive oxide layer on a glass or sapphire superstrate; (ii) depositing a layer of n-CdSe by reactive evaporation on the n + -type layer; and (iii) depositing a layer of p-ZnTe at low temperatures on the n-CdSe to avoid interdiffusion at the junction; (c) applying metalization to either the ZnTe or (Cd/Zn)S; and (d) pressing the upper and lower cells together under suitable heat to bond the upper and lower cells together through the metalization.
Claim 56
Independent Claim
169 words
A method for making a polycrystalline, tandem, photovoltaic transducer, comprising the steps of: (a) forming a lower cell by the steps of: (i) depositing a molybdenum contact over a metal foil substrate; (ii) depositing a graded p-n type CuInSe 2 layer on the contact by simultaneous elemental evaporation, the layer having a portion removed from the contact that is copper-deficient, and having a bandgap of about 1.0 eV; (iii) depositing an n-(Cd,Zn)S layer atop the CuInSe 2 layer; (b) forming an upper cell by the steps of: (i) depositing an n + -type transparent conductive oxide layer on a glass or sapphire superstrate; (ii) depositing a layer of n-CdSe by reactive evaporation on the n + -type layer; and (iii) depositing a layer of p-ZnTe at low temperatures on the n-CdSe to avoid interdiffusion at the junction; (c) applying metalization to either the ZnTe or (Cd/Zn)S; and (d) pressing the upper and lower cells together under suitable heat to bond the upper and lower cells together through the metalization.
Claim 57
Dependent Claim
25 words
The method of claim 48 further comprising the step of applying a substantially optically transparent adhesive to the upper and lower cells around the metalization.
References Cited (Backward Citations)
US4536607A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-07-13 | 1991-01-12 | 1991-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-07-13 | 1995-01-12 | 1995-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-07-13 | 1999-01-12 | 1999-07-14 | $7700.00 | Window Closed / Lapsed |