To remove the Sb2O3 precipitation, the as-prepared solution was allowed to precipitate for 4 hours and then filtered with filter paper. For the fabrication of Sn-doped Sb2Se3 films, various amounts of SnSO4 (0.1 mM, 0.2 mM, and 0.3 mM) as a dopant were added to the filtered solution. The resulting solution was then transferred into a 100 ml Teflon-lined hydrothermal reactor. Mo-coated glass substrates, partially wrapped with Teflon tape and placed face down in a holder, were positioned in the Teflon tank. The reaction was held at 165 o C for 4 hours in an oven. Following the reaction, the autoclave was naturally cooled to room temperature. Then the Sb2Se3 films were successfully deposited on the Mo substrates.