Techniques for Enhancing Performance of Photovoltaic Devices

Abstract

Techniques for improving energy conversion efficiency in photovoltaic devices are provided. In one aspect, an antimony (Sb)-doped film represented by the formula, Cu 1-y In 1-x Ga x Sb z Se 2-w S w , provided, wherein: 0≦x≦1, and ranges therebetween; 0≦y≦0.2, and ranges therebetween; 0.001≦z≦0.02, and ranges therebetween; and 0≦w≦2, and ranges therebetween. A photovoltaic device incorporating the Sb-doped CIGS film and a method for fabrication thereof are also provided.

What is claimed is: 
     
         1 . A method of fabricating a photovoltaic device, comprising the steps of:
 providing a substrate; and   forming an Sb-doped absorber layer on the substrate represented by the formula,
   Cu 1-y In 1-x Ga x Sb z Se 2-w   S   w , 
   wherein:
 0≦x≦1, and ranges therebetween; 
 0≦y≦0.2, and ranges therebetween; 
 0.001≦z≦0.02, and ranges therebetween; and 
 0≦w≦2, and ranges therebetween. 
   
     
     
         2 . The method of  claim 1 , further comprising the steps of:
 forming an n-type buffer layer on a side of the Sb-doped absorber layer opposite the substrate;   forming a transparent conductive contact on a side of the buffer layer opposite the Sb-doped absorber layer; and   forming a metal grid on a side of the transparent conductive contact opposite the buffer layer.   
     
     
         3 . The method of  claim 1 , wherein the substrate comprises glass, metal foil or a polyimide sheet, the method further comprising the step of:
 sputtering molybdenum, tungsten, or chromium onto the glass, metal foil or polyimide sheet to a thickness of from about 0.5 micrometers to about 1 micrometer.   
     
     
         4 . The method of  claim 1 , wherein the step of forming the Sb-doped absorber layer comprises the steps of:
 preparing an Sb-doped nanoparticle precursor ink;   depositing the Sb-doped nanoparticle precursor ink on the substrate; and   annealing the Sb-doped nanoparticle precursor ink deposited on the substrate under H 2 Se.   
     
     
         5 . The method of  claim 4 , wherein the step of preparing the Sb-doped nanoparticle precursor ink comprises the step of:
 adding elemental Sb to a Cu, In and Ga pre-mixture in an acid.   
     
     
         6 . The method of  claim 4 , wherein the step of preparing the Sb-doped nanoparticle precursor ink comprises the step of:
 adding an acid-soluble Sb-containing compound to a Cu, In and Ga pre-mixture in an acid.   
     
     
         7 . The method of  claim 6 , wherein the acid-soluble Sb-containing compound comprises antimony oxide. 
     
     
         8 . The method of  claim 4 , wherein the Sb-doped nanoparticle precursor ink is deposited on the substrate using one or more of doctor blading, ink jet printing, roller coating, spraying, stamping and dip coating. 
     
     
         9 . The method of  claim 1 , wherein the step of forming the Sb-doped absorber layer comprises the step of:
 depositing separately an Sb-source thin film and a film comprising one or more of Cu, In, Ga and Se on the substrate by a vacuum deposition technique.   
     
     
         10 . The method of  claim 9 , wherein the Sb-source thin film comprises an Sb, Sb 2 S 3  or Sb 2 Se 3  thin film. 
     
     
         11 . The method of  claim 9 , wherein the Sb-source thin film is deposited before the film comprising one or more of Cu, In, Ga and Se. 
     
     
         12 . The method of  claim 9 , wherein the Sb-source thin film is deposited after the film comprising one or more of Cu, In, Ga and Se. 
     
     
         13 . The method of  claim 9 , further comprising the step of:
 varying a relative ratio of the Sb-source thin film and the film comprising one or more of Cu, In, Ga and Se to vary an Sb content in the Sb-doped absorber layer.   
     
     
         14 . The method of  claim 1 , wherein the Sb-doped absorber layer has a grain size of from about 0.2 micrometers to about 2 micrometers measured as a longest length of a grain from a cross-section of the Sb-doped absorber layer. 
     
     
         15 . The method of  claim 14 , wherein the longest length of the grain from the cross-section of the Sb-doped absorber layer is greater than or equal to a thickness of the Sb-doped absorber layer. 
     
     
         16 . The method of  claim 1 , wherein the Sb-doped absorber layer has a thickness of from about 200 nanometers to about 2.5 micrometers.