In Situ versus ex Situ Assembly of Aqueous-Based Thioacid Capped CdSe Nanocrystals within Mesoporous TiO₂ Films for Quantum Dot Sensitized Solar Cells

Abstract

We report a straightforward in situ deposition method to directly assemble aqueous thioglycolic acid capped CdSe colloidal quantum dots within mesoporous TiO₂ 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 TiO₂. It permits high loading and uniform distribution of colloidal quantum dots within mesoporous TiO₂ 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