A two-step method to obtain the 2D layers of SnSe2 single phase and study its physical characteristics for photovoltaic and photo-converter devices

The two-dimensional (2D) layers of SnSe 2 , used for various photo-convertor and photovoltaic device applications, were synthesized using a two-step procedure. The Sn-Se alloy was prepared by direct fusion at 1125 °C in a vacuum-sealed quartz ampoule at stage one. Stage two deals with the deposition of 2D layers of Sn-Se alloy on corning glass substrate by thermal evaporation followed by their annealing under vacuum at temperatures between 323 and 573 K. The characteristics of Sn-Se 2D layers vary with change in the annealing temperature. The 2D layers obtained at annealing temperatures (T a ) between 473 and 573 K show high absorption coefficient (α) > 1 × 10 5 cm −1 ; their optical bandgap (E g ) value tunes between 1.84 and 1.96 eV. This bandgap range matches the visible region of the EM spectrum, indicating that these layers are suitable for photovoltaic solar cells. The re-evaporation of 'Se' from the deposited layers was observed at high temperatures, which causes porosity in the synthesized layers. The high porosity value in the SnSe 2 layers was observed at Ta = 573 K; the films obtained at this temperature provide the mobility value of 677cm 2 /V, indicating the layers are more favorable to the electrical behavior of devices.