Integrated solar collectors using epitaxial lift off and cold weld bonded semiconductor solar cells

Abstract

There is disclosed ultrahigh-efficiency single- and multi-junction thin-film solar cells. This disclosure is also directed to a substrate-damage-free epitaxial lift-off (“ELO”) process that employs adhesive-free, reliable and lightweight cold-weld bonding to a substrate, such as bonding to plastic or metal foils shaped into compound parabolic metal foil concentrators. By combining low-cost solar cell production and ultrahigh-efficiency of solar intensity-concentrated thin-film solar cells on foil substrates shaped into an integrated collector, as described herein, both lower cost of the module as well as significant cost reductions in the infrastructure is achieved.

1 - 17 . (canceled) 
     
     
         18 . A thin-film solar cell comprising:
 an active photovoltaic region;   a metal contact bonded to the active photovoltaic region;   a substrate bonded to the metal contact, wherein the substrate is shaped into a compound parabolic collector capable of concentrating electromagnetic radiation onto the active photovoltaic region.   
     
     
         19 . The thin film solar cell of  claim 18 , wherein the substrate comprises a plastic film or metal foil. 
     
     
         20 . The thin film solar cell of  claim 19 , wherein the plastic film comprises polyimide. 
     
     
         21 . A thin film solar cell comprising:
 a cell comprising an active photovoltaic region, a metal contact bonded to the active photovoltaic region, and a substrate bonded to the metal contact; and   a reflective film bonded to the cell, wherein the film is shaped into a compound parabolic collector capable of concentrating electromagnetic radiation onto the active photovoltaic region of the cell.   
     
     
         22 . The thin film solar cell of  claim 21 , wherein the substrate comprises a plastic film or metal foil. 
     
     
         23 . The thin film solar cell of  claim 22 , wherein the plastic film comprises polyimide. 
     
     
         24 . A method for forming a thin-film solar cell, comprising:
 providing a cell comprising an active photovoltaic region, a metal contact bonded to the active photovoltaic region, and a substrate bonded to the metal contact; and   molding the substrate into a compound parabolic collector capable of concentrating electromagnetic radiation onto the active photovoltaic region.   
     
     
         25 . The method of  claim 24 , wherein the substrate is molded by placing the substrate in a thermally conductive or actively cooled preform. 
     
     
         26 . The method of  claim 24 , wherein the substrate comprises a plastic film or metal foil. 
     
     
         27 . The method of  claim 26 , wherein the plastic film comprises polyimide. 
     
     
         28 . A method for forming a thin-film solar cell, comprising:
 providing a cell comprising an active photovoltaic region, a metal contact bonded to the active photovoltaic region, and a substrate bonded to the metal contact;   bonding the cell to a reflective film; and   molding the reflective film into a compound parabolic collector capable of concentrating electromagnetic radiation onto the active photovoltaic device region.   
     
     
         29 . The method of  claim 28 , wherein the reflective film is molded by placing the film in a thermally conductive or actively cooled preform. 
     
     
         30 . The method of  claim 28 , wherein the substrate comprises a plastic film or metal foil. 
     
     
         31 . The method of  claim 30 , wherein the plastic film comprises polyimide. 
     
     
         32 . A method for forming a thin-film solar cell with integrated solar collector, comprising:
 growing one or more first protection layers on a first substrate;   growing a sacrificial layer;   growing one or more second protection layers;   depositing a cell by depositing at least one active photovoltaic cell layer on top of the second protection layer, coating the top active photovoltaic cell layer with a metal, coating a second substrate with a metal, and pressing together the two metal surfaces to form a cold-weld bond;   removing the sacrificial layer by etching to release the cell;   bonding the cell to a reflective film; and   molding the reflective film into a compound parabolic collector capable of concentrating electromagnetic radiation onto the active photovoltaic device region.   
     
     
         33 . The method of  claim 32 , wherein the reflective film is molded by placing the substrate in a thermally conductive or actively cooled preform. 
     
     
         34 . The method of  claim 32 , wherein the second substrate comprises a plastic film or metal foil. 
     
     
         35 . The method of  claim 34 , wherein the plastic film comprises polyimide. 
     
     
         36 . The method of  claim 32 , wherein the metal contact comprises at least one metal chosen from Au, Ag, and Cu. 
     
     
         37 . The method of  claim 32 , wherein the sacrificial layer is AlAs.