Dual Absorber Electrodes

Abstract

Dual absorber electrodes are disclosed. In some embodiments, a dual absorber electrode includes a first absorber material, such as silicon, having a first bandgap, and a second absorber material, such as hematite, deposited on a surface of the first absorber material, the second absorber material having a second bandgap larger than the first bandgap of the first absorber. In some embodiments, the dual absorber electrodes of the present embodiment may be utilized in an electrolytic cell for water splitting.

What is claimed is: 
     
         1 . A dual absorber electrode comprising a first absorber material having a first bandgap; and a second absorber material deposited on a surface of the first absorber material, the second absorber material having a second bandgap larger than the first bandgap of the first absorber. 
     
     
         2 . The electrode of  claim 1  wherein the first absorber material is a silicon nanostructure and the second absorber material is a hematite thin film deposited on the surface of the silicon nanostructure. 
     
     
         3 . The electrode of  claim 1  further comprising a uniform interface between the first absorber material and the second absorber material with low defect densities and low impurity levels. 
     
     
         4 . The electrode of  claim 1  wherein the second absorber material is deposited over the first absorber material in a conformal fashion. 
     
     
         5 . The electrode of  claim 1  wherein the second absorber material is a thin film conformally deposited on the surface of the first absorber material. 
     
     
         6 . The electrode of  claim 1  wherein the first absorber material is a photovoltaic junction. 
     
     
         7 . The electrode of  claim 1  wherein the second absorber material is a photovoltaic junction. 
     
     
         8 . The electrode of  claim 1  further comprising a catalyzing member in electrical contact with the first absorber material for catalyzing hydrogen generation. 
     
     
         9 . The electrode of  claim 8  wherein the first absorber material is a silicon nanostructure and the second absorber material is a hematite thin film deposited on the surface of the silicon nanostructure. 
     
     
         10 . The electrode of  claim 8  wherein a uniform interface is formed between the first absorber material and the second absorber material with low defect densities and low impurity levels. 
     
     
         11 . The electrode of  claim 8  wherein the second absorber material is a photovoltaic junction. 
     
     
         12 . A device for splitting water to generate hydrogen and oxygen comprising:
 a first compartment having a first electrode, the electrode comprising a first absorber material having a first bandgap, and a second absorber material deposited on a surface of the first absorber material, the second absorber material having a second bandgap larger than the first bandgap of the first absorber;   a second compartment having a second electrode for catalyzing hydrogen generation; and   a semi-permeable membrane separating the first compartment and the second compartment.   
     
     
         13 . The device of  claim 12  wherein the first absorber material is a silicon nanostructure and the second absorber material is a hematite thin film deposited on the surface of the silicon nanostructure. 
     
     
         14 . The device of  claim 12  wherein a uniform interface is formed between the first absorber material and the second absorber material with low defect densities and low impurity levels. 
     
     
         15 . The device of  claim 12  wherein the second absorber material is deposited over the first absorber material in a conformal fashion. 
     
     
         16 . The device of  claim 12  wherein the second absorber material is a thin film conformally deposited on the surface of the first absorber material. 
     
     
         17 . The device of  claim 12  wherein the first absorber material is a photovoltaic junction. 
     
     
         18 . The device of  claim 12  wherein the second absorber material is a photovoltaic junction. 
     
     
         19 . A method of fabricating an electrode comprising:
 obtaining a silicon nanostructure;   forming by vapor deposition a layer of hematite on a surface of the silicon nanostructure by exposing the silicon nanostructure to gas precursors of hematite; and   repeating the vapor-depositing to form additional layers of hematite on the surface of the silicon nanostructure.   
     
     
         20 . The method of  claim 19  wherein the silicon nanostructure is a photovoltaic junction.