Synthesis and characterization of Bi-doped antimony sulphide thin films for solar absorption applications

Producing stable semiconducting thin films with low band gap energy by a viable technique is challenging for solar energy harvesting. Herein, Bi-doped Sb2S3 thin films have been deposited on glass substrates by chemical bath deposition (CBD) technique followed by annealing at 400 degrees C. X-ray diffraction (XRD) patterns confirmed the orthorhombic phase of Sb2S3 and successful incorporation of Bi+3 in the host lattice. Raman spectroscopy revealed the characteristic vibrational modes of Sb2S3. Surface of films became smoother and compact with increasing Bi contents. Samples showed wide absorption range in the visible region. Band gap energy (Eg) values were estimated using Tauc's relation and a blue shift in the absorption edge was observed with addition of Bi, thus Eg increased from 1.58 to 1.71 eV. Higher values of absorption coefficient and absorption edge in the visible region suggest that the prepared Sb2S3 thin films can be a right choice of an absorber layer