An innovative approach for fabrication of Cu₂ZnSnSe₄ absorber layers using solutions of elemental metal powders

An innovative approach has been demonstrated for the deposition of Cu₂ZnSnSe₄ (CZTSe) absorber layers. Using a unique, safe solvent combination, moving away from hydrazine, elemental Cu, Zn, Sn and S/Se can be fully dissolved at ambient conditions, with the composition easily controlled. The preparation and the spray deposition of these solutions are performed in air, allowing a quick, easy and inexpensive process. Upon selenisation, large crystals are observed which are identified as the CZTSe kesterite phase using X-ray diffraction and Raman, the latter showing no distinctive signs of any binary or ternary secondary phases. Using this method, CZTSe absorber layers have been prepared for use in thin-film solar cells reaching efficiency of 3.2%. With further device optimisation, improved device performance will be achieved. - Highlights: • A safe and easy approach for preparing solutions of Cu₂ZnSnSe₄ (CZTSe) • A simple and quick deposition of CZTSe absorber layer via spray coating • Identification of CZTSe kesterite phase via Raman spectroscopy and X-ray diffraction • Efficiencies of 3.24% reached, with further device optimisation required • Overall, a low-cost and safer alternative for production of thin-film solar cells