CdTe Quantum Dots-Sensitized TiO2 Nanotube Array Photoelectrodes

TiO2 nanotube array films, formed by anodic oxidation, have been shown to yield high efficiency of charge generation and collection in photoelectrochemical (PEC) devices. However, the wide band gap (3.2 eV) of TiO2 limits the efficiency of these devices in the visible region. In this work, four types of presynthesized CdTe quantum dots (QDs) of different sizes were deposited into the TiO2 nanotubes to serve as the sensitizers, and the performance of the CdTe QD-sensitized TiO2 nanotube arrays was measured in a PEC solar cell. It is found that, with decreasing particle size, the driving force for electron injection increases while the visible light response decreases. Maximum photocurrent was obtained for the QDs that have an absorption peak at 536 nm. Under AM 1.5 G illuminations, a 6 mA/cm(2) Short circuit current density is achieved, which presents a 35 times improvement compared to that based on using a plain TiO2 nanotube film.