Enhancement of photo-characteristics of Bi2Se3 thin films by post heat treatment at optimal temperature range

Thin films of Bi2Se3 have been deposited onto fluorine-doped tin oxide (FTO) – coated glass substrates from non-aqueous bath with the help of galvanostatic electrodeposition technique. The deposited films were subjected to heat treatment at different temperatures in aerated condition and characterized there after. The X-ray diffraction analysis showed the polycrystalline nature of the films and optical absorption technique employed on the as deposited films revealed the presence of direct transition with band gap energy 1.56 eV which after annealing increased up to the value of 1.65 eV. Stoichiometric composition of the film was determined through energy dispersive X-ray analysis. The stoichiometry was maintained within a short temperature range. The scanning electron micrographs of the films demonstrate a ‘fishing net’ type of highly porous structure with ‘foamy’ appearance. In order to ascertain the stability of the films towards anodic oxidation electrochemical polarization studies were conducted in aqueous medium followed by anodic stripping voltammetry to estimate the dissolved cations during polarization. Films annealed within an optimal temperature range were found to bear distinguished photoelectrochemical properties as regard to solar cell applications.

► Thin film of n-Bi2Se3 electrochemically deposited onto TCO coated glass.
► The Eg were tuned by heat treatment and exhibited as in the range of 1.56–1.65 eV.
► The Bi2Se3 films are highly porous ‘fishing net’ type with ‘foamy’ appearance.
► Films display high order of Isc, lower Rct and Rcorr, after annealed at 150 °C.
► High photoconversion efficiency of 3.70%, was obtained after annealed 150 °C.