Solution enhancement for the liable preparation of Cu₂ZnSnS₄ thin films

The role of precursor solution is vital in the chemical spray pyrolysis deposition of Cu₂ZnSnS₄ (CZTS) thin films. The solubility of metal precursors along with organosulfur compound in repetitive conditions is demanding for the preparation of CZTS precursor solution. The regular aqueous solution and a viscous 2-metho solvent were taken for the preparation of CZTS thin films using spray pyrolysis technique. The aqueous and 2-metho films were deposited and characterized to reveal their structural, morphological, optical and electrical properties. The structural studies confirmed the formation of Cu₂ZnSnS₄ tetragonal phase. The film growth on the surface and the roughness values were analyzed from FESEM and AFM analyses which showed a glut roughness for aqueous film. The optical absorbance showed maximum response in the UV–Visible region with a cut off in the near IR region which is a suitable parameter for absorber layer in thin films solar cells. The photoluminescence spectrum gave an emission peak in the near IR region. The electrical measurement specified a carrier concentration of 1.36 × 10¹⁵ cm⁻³ for 2-metho film which was higher than the aqueous ones of 1.25 × 10¹⁵ cm⁻³. The p-type semiconducting behavior of the material was confirmed from the Hall measurement and the impedance analysis was studied. The V–I measurement gave a linear response and the resistance values of the deposited thin films were calculated.