Tuning the properties of sprayed CuZnS films for fabrication of solar cell.

CuZnS is a promising material for solar cells, having mixed structure of Cu_xS and ZnS. In CuZnS thin films prepared by Chemical Spray Pyrolysis, it was observed that the material can be changed from n-type to p-type and electrical conductivity can be increased by 4 orders by just varying the Cu concentration. Increase in concentration of Cu also leads to decrease of band gap from 3.4 eV to 1.8 eV. Films of high concentration of Cu can be used as good absorber and Cu-poor films as buffer/window layer in solar cells. A bilayer heterojunction photovoltaic device could be fabricated using automated spray machine. Here, CuZnS was the absorber layer and In₂S₃ was the buffer layer. Using Ag as top electrode, J-V characteristics of the cell was recorded. For the optimum doped cell, the parameters obtained were V_oc = 0.451 V, J_sc = 5.47 mA/cm², FF = 42.2%, and η = 1.04%. [ABSTRACT FROM AUTHOR]