TiO2 nanorods with CdS quantum dots for optical applications

Abstract

We combine CdS semiconductor quantum dots and single-crystalline rutile TiO2 nanorod arrays to produce a practical quantum dot sensitized solar cell. A facile wet-chemical approach was implemented for growth of this CdS@TiO2 architecture. Rutile TiO2 nanorod arrays with lengths of 1–2 mm and diameters of 40–60 nm was synthesized on fluorine-doped tin oxide glass by a hydrothermal process in a titanium tetrachloride precursor solution. CdS quantum dots with a size of 5–10 nm was deposited onto a TiO2 nanorod surface using an ultrasonic-assisted chemical bath deposition method. The resulting CdS quantum dots and TiO2 nanorods formed a type-II heterojunction and showed increased absorption over visible light range. Incident photon-to-current conversion efficiencies (IPCE) as high as 85% and power conversion efficiencies of 2.54% were obtained using a polysulfide electrolyte.