Titanium incorporation into absorber layer for solar cell

Abstract

A method for fabricating a photovoltaic device includes forming a film including titanium on a conductive layer formed on a substrate. An absorber layer is formed including a Cu—Zn—Sn containing chalcogenide compound with a kesterite structure of the formula: 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 (CZTS) on the film. The absorber layer is annealed to diffuse titanium therein and to recrystallize the CZTS material of the film. A buffer layer is formed on the absorber layer, and a transparent conductive layer is formed on the buffer layer.

What is claimed is: 
     
         1 . A photovoltaic device, comprising:
 a substrate having a metal coating thereon;   an absorber layer formed on the metal coating, the absorber layer including a titanium-doped Cu—Zn—Sn containing chalcogenide compound with a kesterite structure of the formula: 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 (CZTS), wherein an atomic percentage of titanium included in the absorber layer ranges from about 0 to about 0.125;   a buffer layer formed on the absorber layer; and   a transparent conductor formed on the buffer layer.   
     
     
         2 . The device as recited in  claim 1 , further comprising a titanium containing layer disposed between the absorber layer and the metal coating. 
     
     
         3 . The device as recited in  claim 2 , wherein the titanium containing layer includes a thickness of between about 0.5 nm and about 500 nm. 
     
     
         4 . The device as recited in  claim 1 , further comprising an open circuit voltage deficit of less than about 670 mV. 
     
     
         5 . The device as recited in  claim 1 , wherein the device includes a power conversion efficiency (PCE) of greater than 11.0%.