Effect of compact structure on the phase transition in the oxides derived Cu2ZnSnSe4 thin films

•Densification studies were performed to improve the grain size and morphology of the oxides derived CZTSe films.•The CZTSe films showed the dominant CZTSe structure without ZnSe and Cu2SnSe3 secondary phase.•The compressed and untreated CZTSe films showed the Kesterite and Stannite structure respectively.

Cu2ZnSnSe4 (CZTSe) films were prepared by selenization of oxides nanoparticles. A novel densification method was performed to improve the grain size and morphology of the CZTSe films. From absorption spectroscopy measurement, it was also found that the compressed CZTSe films showed Kesterite structure with a band gap of 0.92 eV, while the untreated CZTSe films showed partially disordered Kesterite structure with a band gap of 0.86 eV. The phase transition during the selenization of oxides nanoparticles is affected significantly by the compact density. The nucleation and growth of Kesterite phase is considered to be facilitated by the mass transfer around the particle contacts. The different characterization techniques show that the dense CZTSe layer with very large grain size can be achieved by using compression method.