Preparation of Copper Zinc Tin Sulfide Thin Film Solar Cells by Chemical Synthesis

Abstract

Cu₂ZnSnS₄ (CZTS) is a promising quaternary semiconducting absorber layer in thin film heterojunction solar cells. All the elements of this compound semiconductor were abundant, inexpensive, and non-toxic, hence CZTS is an alternative emerging optoelectronic material for Cu(In,Ga)Se₂ and CdTe solar cells. Using the traditional spray approach, these films were effectively grown at an ideal substrate temperature of 643 K. The deposited films are found to be a kesterite structure using X-ray diffraction studies. The lattice parameters are calculated from the XRD spectrum and are found to be a = b = 5.44 Å and c = 10.86 Å. The energy band gap and optical absorption coefficient are found to be 1.50 eV and above 10⁴ cm^-1 respectively. The material exhibits p-type conductivity. After the chemical spray pyrolysis is completed, the deposited films remain on the hot plate, thus improving the films' crystallinity. A Cu₂ZnSnS₄ solar cell is fabricated using entirely chemical synthesis methods. The absorber layer has been deposited using spray pyrolysis deposition. CdS used as the buffer layer and these films have been successfully deposited through chemical bath deposition. The thin film solar cell exhibits an open circuit voltage and short circuit current of 286 mV and 2.6 mA/cm². To attain reasonable efficiency, work is being done.