Electrochemical deposition of Bi2S3 thin films using dimethylsulfoxide as a solvent

Bi2S3 thin films with different morphology and crystallite size were electrodeposited on conducting glass substrates from a dimethylsulfoxide solution of bismuth chloride and elemental sulfur at various temperatures. Porous Bi2S3 films, constituted of open-packed nanoparticles (< 20 nm), were obtained at low temperature (80 degrees C). Dense Bi2S3 films were obtained in the temperature range of 100-130 degrees C. They were formed of larger close-packed nanocrystals (45 - 100 nm) arranged in columnar agglomerates. Electrodeposition at higher temperatures (150 degrees C) resulted in open-packed large nanocrystals (> 500 nm) that constitute a microstructured film. The stoichiometry of the Bi2S3 films was confirmed by chemical analysis. However, X-ray diffraction indicated distortions in Bi2S3 lattice. Deposition temperature was found to influence the distortion, with the smallest distortion observed for the highest temperature (150 degrees C). Optical gaps in the 1.31-1.45 eV range were estimated for the obtained Bi2S3 films. The influence of the morphology and structural defects on the optical properties of Bi2S3 films was also discussed. (c) 2007 The Electrochemical Society.