Photoelectrochemical (PEC) characterization of chemically deposited Bi 2S 3 thin films from non-aqueous medium

Abstract

Bi 2S 3 thin films have been prepared by chemical bath deposition method using bismuth nitrate, Bi(NO 3) 3 and sodium thiosulphate (Na 2S 2O 3) dissolved in acetic acid and formaldehyde respectively. Films were deposited onto flourine doped tin oxide coated (FTO) glass substrates. The photoelectrochemical (PEC) cell configuration was n-Bi 2S 3/0.25 M NaOH–0.25 M Na 2S–0.25 M S/C. From the current–voltage characteristics (I–V) and capacitance–voltage (C–V) plots, it is concluded that the Bi 2S 3 films are of n-type conductivity. The photovoltaic output characteristics were used to calculate fill factor (FF) and solar conversion efficiency ( η). The low value of η may be due to high value of series resistance and interface states in the cell which are responsible for the recombination mechanism. The magnitude of band gap energy of Bi 2S 3 photoelectrode estimated from spectral response of PEC cell agrees with the magnitude obtained from optical absorption of Bi 2S 3 films. The magnitude of decay constant estimated from transient photoresponse indicated the charge transfer kinetics is of second order.