Compression for smoothing and densifying CuInSe2 and Cu2ZnSnSe4 thin films coating from oxides nanoparticles precursor

Nanoparticle-based approach was a promising coating technique for the formation of CuInSe2 (CISe) and Cu2ZnSnSe4 (CZTSe) thin films solar cell. However, the agglomerations were inevitable during the coating process, which led to form rough and porous films. Densification studies were performed to smooth and densify the oxide nanoparticles derived CISe and CZTSe films in this paper. After compression treatment, the smoothness and density of oxides films have been greatly improved. The compact density significantly affects the phase transition during the selenization. The nucleation and growth of CISe and CZTSe phase are considered to be facilitated by the mass transfer around the particle contacts. Meanwhile, the effects of annealing atmosphere (vacuum or Ar) on the properties of CISe films were also investigated. Selenization under Ar atmosphere with elemental selenium vapor led to better crystalline and larger grain size.