Ink for forming thin film of solar cells and method for preparing the same, CIGS thin film solar cell using the same and manufacturing method thereof

Abstract

Disclosed are an ink containing nanoparticles for formation of thin film of a solar cell and its preparation method, CIGS thin film solar cell having at least one light absorption layer formed by coating or printing the above ink containing nanoparticles on a rear electrode, and a process for manufacturing the same. More particularly, the above absorption layer comprises Cu, In, Ga and Se elements as constitutional ingredients thereof and such elements exist in the light absorption layer by coating or printing an ink that contains Cu 2 Se nanoparticles and (In,Ga) 2 Se 3 nanoparticles on the rear electrode, and heating the treated electrode with the ink. According to the present invention, since Cu(In,Ga)Se 2 , that is, CIGS, thin film is formed using the ink containing nanoparticles, a simple process is preferably used without requirement of vacuum processing or complex equipment and particle size of the thin film, Ga doping concentration, etc. can be easily regulated.

1 . A CIGS thin film solar cell comprising at least one light absorption layer which comprises at least one element selected from Cu, In, Ga, Se and S and is formed by coating or printing an ink that contains Cu 2 (Se 1-x S x ) nanoparticles and (In,Ga) 2 (Se 1-y S y ) 3  nanoparticles on a rear electrode of the cell, wherein x and y satisfy 0≦x≦1 and 0≦y≦1. 
     
     
         2 . The solar cell according to  claim 1 , wherein the ink further contains In 2 (Se 1-z S z ) 3  nanoparticles wherein z satisfies 0≦z≦1. 
     
     
         3 . The solar cell according to  claim 1 , wherein the light absorption layer which comprises a compound with particle size of 0.01 to 100 nm having at least one element selected from Cu, In, Ga, Se and S, and contains dispersant and surfactant in total amount of 0 to 10% by weight to total weight of the light absorption layer. 
     
     
         4 . The solar cell according to  claim 1 , wherein the CIGS thin film solar cell further comprises:
 a substrate;   a rear electrode on the substrate; and   a front electrode layer on the light absorption layer formed on the rear electrode.   
     
     
         5 . (canceled) 
     
     
         6 . The solar cell according to  claim 1 , wherein Ga/(In+Ga) or Cu/(In+Ga) ratio of the said light absorption layer is regulated by a mixing ratio of said Cu 2 (Se 1-x S x ) nanoparticles and said (In,Ga) 2 (Se 1-y S y ) 3  nanoparticles. 
     
     
         7 . The solar cell according to  claim 1 , wherein Ga/(In+Ga) ratio of the said light absorption layer satisfies a range of 0.3 to 0.6. 
     
     
         8 - 15 . (canceled) 
     
     
         16 . A method for manufacturing CIGS thin film solar cell, comprising the steps of:
 coating or printing an ink that contains at least one selected from Cu 2 (Se 1-x S x ) nanoparticles, (In,Ga) 2 (Se 1-y S y ) 3  nanoparticles and In 2 (Se 1-y S z ) 3  nanoparticles on a rear electrode formed on a substrate; and   heating the ink to form a light absorption layer,   wherein x, y and z satisfy 0≦x≦1, 0≦y≦1 and 0≦z≦1.   
     
     
         17 . The method according to  claim 16 , further comprising the steps of:
 coating or printing an ink that contains (In,Ga) 2 (Se 1-w S w ) 3  nanoparticles on the said light absorption layer formed by heating; and   again heating the ink, wherein w satisfies 0≦w≦1.   
     
     
         18 . A method for manufacturing CIGS thin film solar cell, comprising the steps of:
 laminating a first light absorption layer formed by coating or printing an ink that contains (In,Ga) 2 (Se 1-a S a ) 3  nanoparticles and heating the ink, and a second light absorption layer formed by coating or printing another ink that contains Cu 2 (Se 1-b S b ) nanoparticles and heating the ink in turns on a rear electrode formed on a substrate to faun a multi-layer laminate, wherein a and b satisfy 0≦a≦1 and 0≦b≦1.   
     
     
         19 . The method according to  claim 16 , wherein the heating is performed at 500 to 600° C. under Selenium (Se) or Sulfur (S) atmosphere. 
     
     
         20 . The method according to  claim 16 , wherein the diameter of the nanoparticles is in the range of 0.01 to 100 nm. 
     
     
         21 . The method according to  claim 17 , wherein the heating is performed at 500 to 600° C. under Selenium (Se) or Sulfur (S) atmosphere. 
     
     
         22 . The method according to  claim 18 , wherein the heating is performed at 500 to 600° C. under Selenium (Se) or Sulfur (S) atmosphere. 
     
     
         23 . The method according to  claim 17 , wherein the diameter of the nanoparticles is in the range of 0.01 to 100 nm. 
     
     
         24 . The method according to  claim 18 , wherein the diameter of the nanoparticles is in the range of 0.01 to 100 nm.