Fabrication and characterization of kesterite Cu₂ZnSnS₄ thin films deposited by electrostatic spray assisted vapour deposition method

Most of the high efficiency kesterite solar cells are fabricated by vacuum or hydrazine-based solution methods which have drawbacks, such as high cost, high toxicity or explosivity. In our contribution, an alternative non-vacuum and environmental friendly deposition technology called electrostatic spray assisted vapour deposition (ESAVD) has been used for the cost-effective growth of Cu₂ZnSnS₄ (CZTS) thin films with well controlled structure and composition. CZTS films have been characterized using a combination of XRD, XPS, SEM-EDX, AFM, and Raman spectroscopy. The results demonstrated that adherent, uniform and homogeneous CZTS films without apparent secondary phases have been produced by ESAVD. The atomic ratios measured by EDX are Cu/( Zn + Sn) = 0.88 and Zn/Sn = 1.17, which are very close with the reported high ef ficiency solar cells and can be finely tuned by formulating the precursor. CZTS films exhibited a typical optical band gap of 1.53 eV from UV-Vis analysis. Cu₂ZnSnS₄ produced by the ESAVD are being optimized towards the fabrication of high efficiency photovoltaic devices.