TiO2 photoanode sensitized with nanocrystalline Bi2S3: the effect of sensitization time and annealing on its photovoltaic performance

Abstract

This work deals with the sensitization of the porous TiO2 films of thickness about 4 µm deposited on fluorine-doped tin oxide with nanocrystalline Bi2S3 for photovoltaic application. The sensitization was achieved for four different sensitization times employing chemical solution deposition with bismuth nitrate and sodium thiosulphate as precursors for Bi3+ and S2−, respectively. The unsensitized and sensitized photoelectrodes were characterized using X-ray diffractometry, scanning electron microscopy and diffused reflectance spectroscopy. XRD patterns show the signatures of both anatase TiO2 and orthorhombic Bi2S3 in the sensitized photoanodes. However, crystallinity of Bi2S3 increased with increase in sensitization time from 10 to 40 min. The temporal effect of sensitization and annealing on the photovoltaic performance of the solar cells fabricated using four different photoelectrodes was studied using the photocurrent density versus photovoltage curves. Annealing apparently improved the photovoltaic performance of photoanodes. The best performance was obtained for cell fabricated using annealed TiO2/Bi2S3 photoanode after 30 min sensitization time showing Voc ~ 0.37 mV, Jsc ~ 0.52 mA/cm2, FF ~ 68 and 0.43 %.