PbS Quantum Dots Sensitized TiO2 Nanotubes for Photocurrent Enhancement

Abstract

In this paper, well-aligned TiO2 nanotubes (TNTs) sensitized with PbS quantum dots (QDs)/clusters have been fabricated by electrochemical anodization and subsequently ultrasonic-assisted dip coating technique. UV-vis spectroscopy analysis indicate that absorption spectrum of crystallized TNTs with oleic acid (OA)-capped PbS quantum dots is extended to visible light band with strong absorption (wavelength 400–800 nm). Photocurrent characteristics of the TNTs/PbS QDs show that the OA-capped QDs contribute extra electron-hole pairs to enhance photocurrent under UV illumination. The I-V behaviors of TNTs/PbS QDs in forward and reverse bias are well explained by corresponding band diagrams of TiO2-PbS system, which further indicate electrons generation, separation and transportation in these system. This paper gives a systematic study of the subject for TiO2 nanotube arrays loaded with nearly mono-dispersed PbS QDs.