Hybrid Multi-Junction Photovoltaic Cells And Associated Methods

Abstract

A multi-junction photovoltaic cell includes a substrate and a back contact layer formed on the substrate. A low bandgap Group IB-IIIB-VIB 2 material solar absorber layer is formed on the back contact layer. A heterojunction partner layer is formed on the low bandgap solar absorber layer, to help form the bottom cell junction, and the heterojunction partner layer includes at least one layer of a high resistivity material having a resistivity of at least 100 ohms-centimeter. The high resistivity material has the formula (Zn and/or Mg)(S, Se, O, and/or OH). A conductive interconnect layer is formed above the heterojunction partner layer, and at least one additional single-junction photovoltaic cell is formed on the conductive interconnect layer, as a top cell. The top cell may have an amorphous Silicon or p-type Cadmium Selenide solar absorber layer. Cadmium Selenide may be converted from n-type to p-type with a chloride doping process.

1 . A photovoltaic cell, comprising:
 a transparent conductor layer;   a first heterojunction partner layer;   a p-type Cadmium Selenide layer in contact with the first heterojunction partner layer; and   a first electrical contact layer.   
   
   
       2 . The photovoltaic cell of  claim 1 , wherein the first heterojunction partner layer comprises a material selected from the group consisting of Zinc Selenide, Cadmium Sulfide, Cadmium Zinc Selenide, Cadmium Selenide, Zinc Sulfide, Cadmium Oxide, Zinc Oxide, Zinc Magnesium Oxide, Tin Oxide, and Cadmium Zinc Sulfide. 
   
   
       3 . The photovoltaic cell of  claim 1 , further comprising a buffer layer, between the transparent conductor layer and the first heterojunction partner layer. 
   
   
       4 . The photovoltaic cell of  claim 3 , wherein the buffer layer is formed of a material selected from the group consisting of undoped Zinc Oxide, Zinc Magnesium Oxide, and Tin Oxide. 
   
   
       5 . The photovoltaic cell of  claim 1 , wherein the first electrical contact layer is a first back contact layer. 
   
   
       6 . The photovoltaic cell of  claim 1 , wherein the first electrical contact layer is a bilayer. 
   
   
       7 . The photovoltaic cell of  claim 6  wherein the first electrical contact layer contains a layer of doped ZnTe and a layer of a material selected from the group consisting of a metal, and a transparent conducting oxide. 
   
   
       8 . The photovoltaic cell of  claim 1 , wherein the first electrical contact layer comprises a second transparent conductor layer, and further comprising:
 a second heterojunction partner layer,   a IB-IIIB-VIB 2  semiconductor layer, and   a second back contact layer.   
   
   
       9 . The photovoltaic cell of  claim 8  wherein the IB-IIIB-VIB 2  semiconductor layer comprises a layer of Copper-Indium-Diselenide (CIS). 
   
   
       10 . The photovoltaic cell of  claim 8 , wherein the first heterojunction partner layer comprises a material selected from the group consisting of Zinc Selenide, Cadmium Sulfide, Cadmium Zinc Selenide, Cadmium Selenide, Zinc Sulfide, Cadmium Oxide, Zinc Oxide, Zinc Magnesium Oxide, Tin Oxide, and Cadmium Zinc Sulfide. 
   
   
       11 . The photovoltaic cell of  claim 8 , further comprising a buffer layer, between the transparent conductor layer and the first heterojunction partner layer. 
   
   
       12 . The photovoltaic cell of  claim 11 , wherein the buffer layer is formed of a material selected from the group consisting of undoped Zinc Oxide, Zinc Magnesium Oxide, and Tin Oxide. 
   
   
       13 . The photovoltaic cell of  claim 8  wherein the IB-IIIB-VIB 2  semiconductor layer is selected from the group of materials having the approximate formula Cu(In, Ga, or Al) (S, or Se) 2 . 
   
   
       14 . The photovoltaic cell of  claim 8 , wherein the first electrical contact layer comprises a bilayer. 
   
   
       15 . The photovoltaic cell of  claim 14 , wherein the bilayer comprises a layer of doped ZnTe and a layer of a material selected from the group consisting of a metal and a conductive oxide. 
   
   
       16 . The photovoltaic cell of  claim 1 , wherein the p-type Cadmium Selenide layer is made by a process comprising:
 depositing a layer of Cadmium Selenide;   coating the layer of Cadmium Selenide with a solution comprising at least one of chloride selected from the group consisting of chlorides of Group IA elements, chlorides of group IB elements, and chlorides of Group IIIB elements; and   heat-treating the layer of Cadmium Selenide while at least partially preventing evaporation of Selenium from the layer of Cadmium Selenide.   
   
   
       17 . The photovoltaic cell of  claim 16 , wherein Selenium is at least partially prevented from evaporating from the layer of Cadmium Selenide during the step of heat-treating by executing the step of heat-treating in a Selenium enriched atmosphere. 
   
   
       18 . The photovoltaic cell of  claim 16 , wherein Selenium is at least partially prevented from evaporating from the layer of Cadmium Selenide during the step of heat-treating by physically impeding the flow of Selenium vapor from the layer of Cadmium Selenide. 
   
   
       19 . The photovoltaic cell of  claim 16 , the solution further comprising Cadmium Chloride. 
   
   
       20 . A hybrid multi-junction photovoltaic cell, comprising:
 a polymer substrate for providing mechanical support for the photovoltaic cell;   a back contact layer formed on the substrate;   a bottom solar absorber layer formed on the back contact layer, the bottom solar absorber layer including a material selected from the group consisting of a low bandgap Group IB-IIIB-VIB 2  material having bulk p-type character, and an alloy of a low bandgap Group IB-IIIB-VIB 2  material having bulk p-type character;   a heterojunction partner layer formed on the bottom solar absorber layer;   a layer of p-type semiconductor formed above the heterojunction partner layer;   a layer of intrinsic semiconductor formed on the layer of p-type semiconductor; and   a layer of n-type semiconductor formed on the layer of intrinsic semiconductor.   
   
   
       21 . The photovoltaic cell of  claim 20 , the polymer substrate being formed of polyimide. 
   
   
       22 . The photovoltaic cell of  claim 20 , the bottom solar absorber layer comprising a material selected from the group consisting of Copper Indium DiSelenide, Copper Indium DiTelluride, and an alloy formed of Copper Indium DiSelenide and at least one of Gallium, Aluminum, Tellurium and Sulfur. 
   
   
       23 . The photovoltaic cell of  claim 20 , the heterojunction partner layer comprising an n-type material. 
   
   
       24 . The photovoltaic cell of  claim 20 , the heterojunction partner layer comprising at least one layer of a high resistivity material having a resistivity of at least 100 ohms-centimeter, the high resistivity material being a material having the formula (Zn and/or Mg)(S, Se, O, and/or OH). 
   
   
       25 . The photovoltaic cell of  claim 24 , wherein the at least one layer of high resistivity material of the heterojunction partner layer has a resistivity of at least 1,000 ohms-centimeter. 
   
   
       26 . The photovoltaic cell of  claim 24 , the heterojunction partner layer being formed using a chemical vapor deposition process. 
   
   
       27 . The photovoltaic cell of  claim 20 , further comprising an interconnect layer disposed between the heterojunction partner layer and the layer of p-type semiconductor. 
   
   
       28 . The photovoltaic cell of  claim 27 , the interconnect layer comprising a material selected from the group consisting of doped Zinc Oxide, undoped Zinc Oxide, Indium Tin Oxide, doped Tin Oxide, undoped Tin Oxide, n-type amorphous Silicon, n-type amorphous Silicon Germanium, hydrogenated amorphous Silicon Carbide, and n-type microcrystalline Silicon. 
   
   
       29 . The photovoltaic cell of  claim 20 , the back contact layer comprising Molybdenum. 
   
   
       30 . The photovoltaic cell of  claim 20 , the layer of p-type semiconductor and the layer of n-type semiconductor each being formed from a material selected from the group consisting of hydrogenated amorphous Silicon, hydrogenated amorphous Silicon Germanium, hydrogenated amorphous Silicon Carbide, nanocrystalline Silicon, and microcrystalline Silicon. 
   
   
       31 . The photovoltaic cell of  claim 20 , the layer of intrinsic semiconductor being formed of hydrogenated amorphous Silicon Germanium. 
   
   
       32 . The photovoltaic cell of  claim 20 , further comprising at least one additional single junction photovoltaic cell formed above the layer of n-type semiconductor. 
   
   
       33 . A module of a plurality of hybrid multi-junction photovoltaic cells, comprising:
 a substrate for providing mechanical support for the photovoltaic cells;   a back contact layer formed on the substrate;   a bottom solar absorber layer formed on the back contact layer, the bottom solar absorber layer including a material selected from the group consisting of a low bandgap Group IB-IIIB-VIB 2  material having bulk p-type character, and an alloy of a low bandgap Group IB-IIIB-VIB 2  material having bulk p-type character;   an n-type heterojunction partner layer formed on the bottom solar absorber layer;   a contact layer of p-type semiconductor formed above the heterojunction partner layer;   a primary solar absorber layer formed on the contact layer of p-type semiconductor, the primary solar absorber layer formed of a material selected from the group consisting of an intrinsic semiconductor and a p-type semiconductor;   a layer of n-type semiconductor formed on the primary solar absorber layer;   a top contact layer formed on the layer of n-type semiconductor;   at least one first isolating scribe extending at least from a top surface of the layer of n-type semiconductor to a top surface of the substrate, the first isolating scribe being filled with an insulating material;   at least one connecting scribe extending at least from the top surface of the layer of n-type semiconductor to a top surface of the back contact layer, the connecting scribe being filed with a conductive material; and   at least one second isolating scribe extending at least from a top surface of the top contact layer to a top surface of the bottom solar absorber layer.   
   
   
       34 . The module of  claim 33 , the heterojunction partner layer being formed of at least one layer of a high resistivity material having a resistivity of at least 100 ohms-centimeter, the high resistivity material being a material having the formula (Zn and/or Mg)(S, Se, O, and/or OH). 
   
   
       35 . The module of  claim 34 , wherein the heterojunction partner layer is formed using a chemical vapor deposition process. 
   
   
       36 . The module of  claim 34 , wherein the at least one layer of high resistivity material of the heterojunction partner layer has a resistivity of at least 1,000 ohms-centimeter. 
   
   
       37 . The module of  claim 33 , further comprising a conductive interconnect layer disposed between the heterojunction partner layer and the contact layer of p-type semiconductor, the conductive interconnect layer comprising a material selected from the group consisting of doped Zinc Oxide, Indium Tin Oxide, doped Tin Oxide, n-type amorphous Silicon, n-type amorphous Silicon Germanium, n-type hydrogenated amorphous Silicon Carbide, and n-type microcrystalline Silicon. 
   
   
       38 . The module of  claim 33 , the contact layer of p-type semiconductor and the layer of n-type semiconductor each being formed from a material selected from the group consisting of hydrogenated amorphous Silicon, hydrogenated amorphous Silicon Germanium, hydrogenated amorphous Silicon Carbide, nanocrystalline Silicon, and microcrystalline Silicon, and the primary solar absorber layer being formed of hydrogenated amorphous Silicon Germanium. 
   
   
       39 . The module of  claim 33 , the contact layer of p-type semiconductor being doped ZnTe, and the primary solar absorber layer being p-type CdSe. 
   
   
       40 . The module of  claim 33 , further comprising at least one additional single junction photovoltaic cell disposed between the heterojunction partner layer and the contact layer of p-type semiconductor. 
   
   
       41 . A multi-junction photovoltaic cell, comprising:
 a substrate for providing mechanical support for the photovoltaic cell;   a back contact layer formed on the substrate;   a solar absorber layer formed on the back contact layer, the solar absorber layer being formed of a low bandgap Group IB-IIIB-VIB 2  material having bulk p-type character;   a heterojunction partner layer formed on the solar absorber layer, the heterojunction partner layer comprising at least one layer of a high resistivity material having a resistivity of at least 100 ohms-centimeter, the high resistivity material being a material having the formula (Zn and/or Mg)(S, Se, O, and/or OH);   a conductive interconnect layer formed above the heterojunction partner layer; and   at least one additional single-junction photovoltaic cell formed on the conductive interconnect layer.   
   
   
       42 . The photovoltaic cell of  claim 41 , wherein the at least one layer of high resistivity material of the heterojunction partner layer has a resistivity of at least 1,000 ohms-centimeter. 
   
   
       43 . The photovoltaic cell of  claim 41 , the heterojunction partner layer being formed using a chemical vapor deposition process. 
   
   
       44 . The photovoltaic cell of  claim 41 , the substrate being formed from a material selected from the group consisting of a polymer, a reinforced polymer, polyimide, a metal foil, an insulated metal foil, and glass. 
   
   
       45 . The photovoltaic cell of  claim 41 , the low bandgap Group IB-IIIB-VIB 2  material being selected from the group consisting of Copper Indium DiSelenide, Copper Indium DiTelluride, an alloy formed of Copper Indium DiSelenide and at least one of Gallium, Aluminum, Tellurium and Sulfur, and an alloy formed of Copper Indium DiTelluride and at least one of Gallium, Aluminum, Selenium and Sulfur. 
   
   
       46 . The photovoltaic cell of  claim 41 , further comprising a buffer layer disposed between the heterojunction partner layer and the conductive interconnect layer. 
   
   
       47 . The photovoltaic cell of  claim 41 , the additional single-junction photovoltaic cell comprising a solar absorber layer formed of a material selected from the group consisting of a Cu(In, Ga, Al)Se 2  compound, a Cu(In, Ga, Al)S 2  compound, hydrogenated amorphous Silicon, hydrogenated amorphous Silicon Germanium alloy, a (Cd, Zn, Mg, Mn)Te compound, and Cadmium Selenide. 
   
   
       48 . The photovoltaic cell of  claim 41 , the additional single-junction photovoltaic cell comprising a solar absorber layer formed of p-type Cadmium Selenide. 
   
   
       49 . A method of making a p-type Cadmium Selenide semiconductor material, comprising:
 depositing a layer of Cadmium Selenide;   coating the layer of Cadmium Selenide with a solution comprising a solvent and at least one of chloride selected from the group consisting of chlorides of Group IA elements, chlorides of group IB elements, and chlorides of Group IIIB elements; and   heating the layer of Cadmium Selenide in an environment having an ambient temperature of between 300 and 500 degrees Celsius for a time between three and thirty minutes while at least partially preventing the evaporation of Selenium from the layer of Cadmium Selenide.   
   
   
       50 . The method of  claim 49 , wherein Selenium is at least partially prevented from evaporating from the layer of Cadmium Selenide during the step of heating by executing the step of heating in a Selenium enriched atmosphere. 
   
   
       51 . The method of  claim 49 , wherein Selenium is at least partially prevented from evaporating from the layer of Cadmium Selenide during the step of heating by physically impeding the evaporation of Selenium from the layer of Cadmium Selenide. 
   
   
       52 . The method of  claim 49 , wherein the solution comprises Copper Chloride and a solvent. 
   
   
       53 . The method of  claim 49 , wherein the solution comprises Gallium Chloride and a solvent. 
   
   
       54 . The method of  claim 49 , wherein the solution comprises Copper Chloride, Gallium Chloride, and a solvent. 
   
   
       55 . The method of  claim 49 , wherein the solution further comprises Cadmium Chloride. 
   
   
       56 . A method of making a photovoltaic device, comprising:
 depositing a contact layer;   depositing a layer of Cadmium Selenide;   coating the layer of Cadmium Selenide with a solution comprising a solvent and at least one of chloride selected from the group consisting of chlorides of Group IA elements, chlorides of group IB elements, and chlorides of Group IIIB elements;   heating the layer of Cadmium Selenide in an environment having an ambient temperature of between 300 and 500 degrees Celsius for a time between three and thirty minutes while at least partially preventing the evaporation of Selenium from the layer of Cadmium Selenide;   depositing a heterojunction partner layer; and   depositing a transparent conductor layer.   
   
   
       57 . The method of  claim 56 , wherein Selenium is at least partially prevented from evaporating from the layer of Cadmium Selenide during the step of heating by executing the step of heating in a Selenium enriched atmosphere. 
   
   
       58 . The method of  claim 56 , wherein Selenium is at least partially prevented from evaporating from the layer of Cadmium Selenide during the step of heating by physically impeding the evaporation of Selenium from the layer of Cadmium Selenide. 
   
   
       59 . The method of  claim 56 , wherein the solution comprises Copper Chloride and a solvent. 
   
   
       60 . The method of  claim 56 , wherein the solution comprises Gallium Chloride and a solvent. 
   
   
       61 . The method of  claim 56 , wherein the solution comprises Copper Chloride, Gallium Chloride, and a solvent. 
   
   
       62 . The method of  claim 56 , wherein the solution further comprises Cadmium Chloride. 
   
   
       63 . The method of  claim 56 , wherein the heterojunction partner layer is a material selected from the group consisting of Zinc Selenide, Cadmium Sulfide, Cadmium Zinc Selenide, Cadmium Selenide, Zinc Sulfide, Cadmium Oxide, Zinc Oxide, Zinc Magnesium Oxide, Tin Oxide, and Cadmium Zinc Sulfide. 
   
   
       64 . The method of  claim 56 , further comprising depositing an undoped buffer layer between the heterojunction partner layer and the transparent conductor layer. 
   
   
       65 . The method of  claim 56 , wherein the contact layer is a bilayer. 
   
   
       66 . The method of  claim 65 , wherein the contact layer comprises a layer of doped ZnTe and a layer of a material selected from the group consisting of a metal, and a transparent conducting oxide. 
   
   
       67 . A method of making a photovoltaic device, comprising:
 depositing a transparent conductor layer;   depositing a heterojunction partner layer;   depositing a layer of Cadmium Selenide;   coating the layer of Cadmium Selenide with a solution comprising a solvent and at least one of chloride selected from the group consisting of chlorides of Group IA elements, chlorides of group IB elements, and chlorides of Group IIIB elements;   heating the layer of Cadmium Selenide in an environment having an ambient temperature of between 300 and 500 degrees Celsius for a time between three and thirty minutes while at least partially preventing the evaporation of Selenium from the layer of Cadmium Selenide; and   depositing a contact layer.   
   
   
       68 . The method of  claim 67 , wherein Selenium is at least partially prevented from evaporating from the layer of Cadmium Selenide during the step of heating by executing the step of heating in a Selenium enriched atmosphere. 
   
   
       69 . The method of  claim 67 , wherein Selenium is at least partially prevented from evaporating from the layer of Cadmium Selenide during the step of heating by physically impeding the evaporation of Selenium from the layer of Cadmium Selenide. 
   
   
       70 . The method of  claim 67 , wherein the solution comprises Copper Chloride and a solvent. 
   
   
       71 . The method of  claim 67 , wherein the solution comprises Gallium Chloride and a solvent. 
   
   
       72 . The method of  claim 67 , wherein the solution comprises Copper Chloride, Gallium Chloride, and a solvent. 
   
   
       73 . The method of  claim 67 , wherein the solution further comprises Chloride. 
   
   
       74 . The method of  claim 67 , wherein the heterojunction partner layer is a layer of a material selected from the group consisting of Zinc Selenide, Cadmium Sulfide, Cadmium Zinc Selenide, Cadmium Selenide, Zinc Sulfide, Cadmium Oxide, Zinc Oxide, Zinc Magnesium Oxide, Tin Oxide, and Cadmium Zinc Sulfide. 
   
   
       75 . The method of  claim 67 , further comprising depositing an undoped buffer layer between the transparent conductor layer and the heterojunction partner layer. 
   
   
       76 . The method of  claim 67 , wherein the contact layer is a bilayer. 
   
   
       77 . The method of  claim 76 , wherein the contact layer comprises a layer of doped ZnTe and a layer of a material selected from the group consisting of a metal layer, and a transparent conducting oxide layer. 
   
   
       78 . A process for forming a hybrid multi-junction photovoltaic cell, comprising:
 forming a first single-junction photovoltaic cell on a substrate, including the steps of:
 forming a first back contact layer on the substrate, 
 forming a first solar absorber layer on the back contact layer, the first solar absorber layer being formed of a low bandgap Group IB-IIIB-VIB 2  material having bulk p-type character, 
 forming a first heterojunction partner layer on the first solar absorber layer, the first heterojunction partner layer comprising at least one layer of a high resistivity material having a resistivity of at least 100 ohms-centimeter, the high resistivity material being a material having the formula (Zn and/or Mg)(S, Se, O, and/or OH); 
   forming a conductive interconnect layer above the first heterojunction partner layer of the first single-junction photovoltaic cell; and   forming at least one additional single-junction photovoltaic cell above the conductive interconnect layer.   
   
   
       79 . The process of  claim 78 , wherein the at least one layer of high resistivity material of the heterojunction partner layer has a resistivity of at least 1,000 ohms-centimeter. 
   
   
       80 . The process of  claim 78 , the low bandgap Group IB-IIIB-VIB 2  material being selected from the group consisting of Copper Indium DiSelenide, Copper Indium DiTelluride, an alloy formed of Copper Indium DiSelenide and at least one of Gallium, Aluminum, Tellurium and Sulfur. 
   
   
       81 . The process of  claim 78 , the step of forming the first heterojunction partner layer including one of performing a chemical vapor deposition process, a wet chemical bath deposition process, and a low energy sputtering process. 
   
   
       82 . The process of  claim 81 , the first heterojunction partner layer being formed using a chemical vapor deposition process. 
   
   
       83 . The process of  claim 78 , the step of forming the first solar absorber layer including performing at least of one a selenization process, a sulfurization process, a tellurization process, a thermal evaporation process, an electron beam evaporation process, a sputtering process, an electrodeposition process, a molecular beam epitaxy process, and a chemical vapor deposition process. 
   
   
       84 . The process of  claim 78 , the step of forming at least one additional single-junction photovoltaic cell comprising:
 forming a second back contact layer on the conductive interconnect layer, and   forming a second solar absorber layer on the second back contact layer, the second solar absorber layer having a higher bandgap energy than the first solar absorber layer.   
   
   
       85 . The process of  claim 84 , the second solar absorber layer being formed of a material selected from the group consisting of a Cu(In, Ga, Al)Se 2  compound, a Cu(In, Ga, Al)S 2  compound, hydrogenated amorphous Silicon, hydrogenated amorphous Silicon Germanium alloy, a (Cd, Zn, Mg, Mn)Te compound, and Cadmium Selenide.