One-pot hydrothermal synthesis of thioglycolic acid-capped CdSe quantum dots-sensitized mesoscopic TiO2 photoanodes for sensitized solar cells

In this work, colloidal CdSe QDs capped with a short chain thiol ligand thioglycolic acid (TGA) were prepared using a one-pot synthesis route in aqueous medium. This method integrates colloidal QDs synthesis and assembly of QDs in a single step due to the use of TGA, which serves as a stabilizer to control the formation of QDs and a linker to tether CdSe QDs to TiO2 during the synthesis of QDs, and it could achieve high surface coverage of high-quality QDs on TiO2 electrodes. The hydrothermal temperature is found to play an important role in determining the size of CdSe QDs and photovoltaic properties of the resulting TiO2/CdSe photoanodes. To further improve the fill factor and efficiency of solar cells, PbS/CuS films were prepared with chemical bath deposition method and used instead of the usual Pt as counter electrodes (CEs). PbS/CuS CEs show superior electrocatalytic activity for the reduction of polysulfide than Pt. An optimized TiO2/CdSe based QDSSC in combination with the PbS/CuS CEs achieved a champion PCE of 4.18% under one sun illumination (100 mW cm−2).