Physical Properties of the Absorber Layer Sn2Sb2S5 thin Films for Photovoltaics

Tin antimony sulphide thin films have been deposited on glass substrate by thermal evaporation technique at a chamber pressure of 10-4 torr. For the characterization purpose, thin films were deposited and annealed in argon gas at 100 °C, 150 °C and 250 °C. The physical properties of the films have been inspected relating annealing temperature. XRD studies revealed that both the as deposited and annealed films exist in Sn2Sb2S5 phase. The absorption coefficient of the annealed films was found to be ~105 cm-1. Photoconductivity response of these films was also fine and enhanced with the increasing temperature. However, the transmittance of the films investigated was quite low. No transmittance was found below 750 nm which decreased with annealing temperature. The band gap calculated by ellipsometry technique was in the range 2.5-1.6 eV. Thickness of the film was observed as 1450 nm and the films possess n-type conductivity.