In situ versus ex situ assembly of aqueous-based thioacid capped cdse nanocrystals within mesoporous TiO 2 films for quantum dot sensitized solar cells

We report a straightforward in situ deposition method to directly assemble aqueous thioglycolic acid capped CdSe colloidal quantum dots within mesoporous TiO ₂ thin films by a low-temperature hydrothermal route. This approach integrates linker assisted adsorption and colloidal quantum dot synthesis in a single step due to the use of thioglycolic acid as the capping agent for the quantum dots and tethering agent for the TiO ₂. It permits high loading and uniform distribution of colloidal quantum dots within mesoporous TiO ₂ electrodes with a greatly improved photovoltaic performance as quantum dot sensitized solar cells, reaching efficiencies as high as 2.2% under one sun illumination conditions after ZnS treatment, compared to the ex situ assembly technique of adsorption of presynthesized semiconductor nanocrystals. © 2011 American Chemical Society.