Influence of CdS Morphology on the Efficiency of Dye-Sensitized Solar Cells

Cadmium sulfide (CdS) used in dye-sensitized solar cells (DSSCs) is currently mainly synthesized by chemical bath deposition, vacuum evaporation, spray deposition, chemical vapor deposition, electrochemical deposition, sol-gel, solvothermal, radio frequency sputtering, and hydrothermal process. In this paper, CdS was synthesized by hydrothermal process and used with a mixture of titanium dioxide anatase and rutile (TiO_2(A+R)) to build the photoanode, whereas the counter electrode was made of nanocomposites of conductive polymer polyaniline (PANI) and multiwalled carbon nanotubes (MWCNTs) deposited on a fluorine-doped tin oxide substrate. Two morphologies of CdS have been obtained by using hydrothermal process: branched nanorods (CdS_BR) and straight nanorods (CdS_NR). The present work indicates that controlling the morphology of CdS is crucial to enhance the efficiency of DSSCs device. Indeed, the higher power conversion energy of 1.71% was achieved for a cell CdS_BR-TiO_2(A+R)/PANI-MWCNTs under 100 mW/cm², whereas the power conversion energy of 0.97 and 0.83% for CdS_NR-TiO_2(A+R)/PANI-MWCNTs and TiO_2(A+R)/PANI-MWCNTs, respectively. Therefore, by increasing the surface to volume ratio of CdS nanostructures and the crystallite size into those structures opens the way to low-cost chemical production of solar cells.