Photosensitization of TiO₂ Layers with CdSe Quantum Dots: Correlation between Light Absorption and Photoinjection

Abstract

Injection of photoelectrons from colloidal CdSe quantum dots (QDs) capped by thioglycolic acid into compact ultrathin TiO2 layers was investigated by direct detection of modulated charge separation with surface photovoltage spectroscopy. A size-dependent peak related to light absorption in the CdSe QDs and charge transfer to TiO2 was observed for QDs of different sizes. Correlation between CdSe QDs absorption and photoelectron injection into TiO2 has been demonstrated. Our results show that surface photovoltage spectroscopy is a valuable tool to determine the effectiveness of carrier injection from colloidal semiconductor QDs to electron transport materials in advanced solar cell configurations.