Photoelectrochemical characterization of Bi₂S₃ thin films deposited by modified chemical bath deposition

Abstract

For the photoelectrochemical (PEC) solar cell, the prime requirement is that photoelectrode/ photoanode should have bandgap close to the maximum in the visible spectrum. Bismuth sulphide (Bi₂S₃) is challenging material because of its mid-way bandgap (<i style="">E_g</i> = 1.74 eV) and absorption coefficient of the order of 10⁴cm^-1. In the present investigation, bismuth sulphide (Bi₂S₃) thin films of thickness about 0.14 mm have been prepared by using modified chemical bath deposition method onto glass and fluorine doped tin oxide (FTO) coated glass substrate under optimized conditions. The films are annealed at 200ºC for 2 h in air. It is found that deposited films turn from amorphous to polycrystalline after annealing. The Bi₂S₃/NaOH-S-Na₂S/C cell has been fabricated by using Bi₂S₃ annealed films and their photoelectrochemical performance has been studied. It is found that Bi₂S₃ films are photoactive. However, conversion efficiency is low (0.056%) due to low series and high shunts resistance of Bi₂S₃ films.