Controllable indium doping for high efficiency czts thin-film solar cells

Abstract

A photovoltaic device includes a first contact layer formed on a substrate. An absorber layer includes Cu—Zn—Sn—S(Se) (CZTSSe) on the first contact layer. A buffer layer is formed in contact with the absorber layer. Metal dopants are dispersed in a junction region between the absorber layer and the buffer layer. The metal dopants have a valence between the absorber layer and the buffer layer to increase junction potential. A transparent conductive contact layer is formed over the buffer layer.

1 . A photovoltaic device, comprising:
 a first contact layer formed on a substrate;   an absorber layer including Cu—Zn—Sn—S(Se) (CZTSSe) on the first contact layer;   a buffer layer formed in contact with the absorber layer;   metal dopants dispersed in a junction region between the absorber layer and the buffer layer, the metal dopants having a valence between the absorber layer and the buffer layer to increase junction potential; and   a transparent conductive contact layer formed over the buffer layer.   
     
     
         2 . The device as recited in  claim 1 , wherein the CZTSSe includes Cu 2−x Zn 1+y Sn(S 1−z Se z ) 4+q  wherein 0≦x≦1; 0≦y≦1; 0≦z≦1; −1≦q≦1. 
     
     
         3 . The device as recited in  claim 1 , wherein the buffer layer includes a semiconductor material including one of Cd or Zn. 
     
     
         4 . The device as recited in  claim 1 , wherein the buffer layer includes one or more of CdTe, CdS, ZnS, Zn(O,S) or ZnO. 
     
     
         5 . The device as recited in  claim 1 , wherein the buffer layer includes CdS and the metal dopants include In metal. 
     
     
         6 . The device as recited in  claim 5 , wherein the CZTSSe includes a valence of +4 for its Sn, the In metal includes a valence of +3 and the CdS includes a valence of +2 for its Cd. 
     
     
         7 . A photovoltaic device, comprising:
 a first contact layer formed on a substrate;   an absorber layer including Cu—Zn—Sn—S(Se) (CZTSSe) on the first contact layer;   a CdS buffer layer formed in contact with the absorber layer;   In metal dopants dispersed in a junction region between the absorber layer and the buffer layer, the metal dopants having a valence between the absorber layer and the buffer layer to increase junction potential; and   a transparent conductive contact layer formed over the buffer layer.   
     
     
         8 . The device as recited in  claim 7 , wherein the CZTSSe includes Cu 2−x Zn 1+y Sn(S 1−z Se z ) 4+q  wherein 0≦x≦1; 0≦y≦1; 0≦z≦1; −1≦q≦1. 
     
     
         9 . The device as recited in  claim 7 , wherein the CZTSSe includes a valence of +4 for its Sn, the In metal includes a valence of +3 and the CdS includes a valence of +2 for its Cd. 
     
     
         10 .- 20 . (canceled)