Method for producing a film by cu2znsns4 silar

Abstract

The present invention relates to a method for manufacturing a film of Cu 2 ZnSnS 4 (CZTS) on a metal or metal oxide substrate by successive ion layer adsorption and reaction (SILAR), characterized by the fact that it comprises at least two cycles, each cycle comprising the following successive steps: immersion of the substrate in a cationic solution comprising copper sulfate (CuSO 4 ), tin sulfate (SnSO 4 ) and zinc sulfate (ZnSO 4 ), referred to as the precursors; rinsing by immersion of the substrate in deionized water; immersion of the substrate in an anionic solution comprising sodium sulfide (Na 2 S); rinsing by immersion of the substrate in deionized water; the concentration ratio of the copper (Cu 2+ ), zinc (Zn 2+ ) and tin (Sn 2+ ) cations and of the sulfur (S 2− ) anion is 1:1:1:1 or 1:0.5:0.5:1. The invention will be applicable more particularly in the photovoltaic field, especially for production of thin-film, especially nanostructured photovoltaic cells, such as the ETA (Extremely Thin Absorber) cell.

1 . A method for manufacturing a film of Cu 2 ZnSnS 4  (CZTS) on a metal or metal oxide substrate by successive ion layer adsorption and reaction (SILAR),
 wherein the method comprises at least two cycles, each cycle comprising, in the following order:
 immersing the substrate in a cationic solution comprising copper sulfate (CuSO 4 ), tin sulfate (SnSO 4 ) and zinc sulfate (ZnSO 4 ), as precursors; 
 rinsing, by immersion, the substrate in deionized water; 
 immersing the substrate in an anionic solution comprising sodium sulfide (Na 2 S); and 
 rinsing, by immersion, the substrate in deionized water; 
   wherein a concentration ratio of copper (Cu 2+ ), zinc (Zn 2+ ) and tin (Sn 2+ ) cations and of sulfur anion (S 2− ) anion is 1:1:1:1 or 1:0.5:0.5:1.   
     
     
         2 . The method according to  claim 1 , wherein a concentration of each precursor in the cationic solution is between 5 and 20 mM. 
     
     
         3 . The method according to  claim 1 , wherein a concentration of sodium sulfide (Na 2 S) in the anionic solution is between 5 and 20 mM. 
     
     
         4 . The method according to  claim 1 , wherein the concentrations of the precursors in the cationic solution are 10 mM copper sulfate (CuSO 4 ), 10 mM tin sulfate (SnSO 4 ) and 10 mM zinc sulfate (ZnSO 4 ). 
     
     
         5 . The method according to  claim 1 , wherein a concentration of sodium sulfide (Na 2 S) in the anionic solution is 10 mM. 
     
     
         6 . The method according to  claim 1 , wherein a duration of immersion of the substrate in the cationic or anionic solution is between 15 and 25 seconds. 
     
     
         7 . The method according to  claim 1 , wherein a duration of immersion of the substrate in the deionized water for rinsing is longer than or equal to 15 seconds. 
     
     
         8 . The method according to  claim 1 , wherein the cationic solution, the anionic solution, or both, is an aqueous solution. 
     
     
         9 . The method according to  claim 1 , wherein the cationic solution has a pH of 5. 
     
     
         10 . The method according to  claim 1 , wherein the anionic solution has a pH of 12. 
     
     
         11 . The method according to  claim 1 , further comprising, after the at least two cycles, annealing at 400° C. under a neutral atmosphere. 
     
     
         12 . The method according to  claim 1 , wherein the substrate is nanostructured. 
     
     
         13 . The method according to  claim 1 , wherein the substrate comprises nanowires of zinc oxide. 
     
     
         14 . The method according to  claim 1 , comprising at least fifteen cycles. 
     
     
         15 . A nanostructured surface covered by a homogeneous film having a minimum thickness of 10 nm of a CZTS phase obtained by the method according to  claim 1 . 
     
     
         16 . A nanowire of metal oxide covered by a homogeneous film of a CZTS phase obtained by the method according to  claim 1 . 
     
     
         17 . The method according to  claim 1 , comprising from fifteen to twenty cycles.