Effect of air annealing on the band gap and optical properties of SnSb2S4 thin films for solar cell application

Tin antimony sulphide (SnSbS) thin films were deposited on glass substrate using thermal vacuum evaporation techniques from tin sulphide and antimony sulphide pellets using the two source technique. The films were thermally annealed at 150 °C, 200 °C and 300 °C in tube furnace. XRD study shows the SnSb2S4 phase formation for the films. The 300 °C annealed films show good photoconductivity response and low transmittance in the range of 400–1100 nm. The band gaps calculated using ellipsometric techniques were in the range of 2.75–1.65 eV. The absorption coefficient of the films is ∼105 cm−1 while the refractive index of the 300 °C annealed film changes from 1.5 to 2.5.

► Tin antimony sulphide (SnSb2S4) thin films were deposited on glass substrates.
► Air annealing increases the photoconductivity response of the films.
► Effect of annealing on band gaps and absorption coefficients is discussed.