CdSxSe1-x alloyed quantum dots-sensitized solar cells based on different architectures of anodic oxidation TiO2 film

Nanostructured TiO2 translucent films with different architectures including TiO2 nanotube (NT), TiO2 nanowire (NW), and TiO2 nanowire/nanotube (NW/NT) have been produced by second electrochemical oxidization of TiO2 NT with diameter around 90-110 nm via modulation of applied voltage. These TiO2 architectures are sensitized with CdSxSe1-x alloyed quantum dots (QDs) in sizes of around 3-5 nm aiming to tune the response of the photoelectrochemical properties in the visible region. One-step hydrothermal method facilitates the deposition of CdSxSe1-x QDs onto TiO2 films. These CdSxSe1-x QDs exhibit a tunable range of light absorption with changing the feed molar ratio of S:Se in precursor solution, and inject electrons into TiO2 films upon excitation with visible light, enabling their application as photosensitizers in sensitized solar cells. Power conversion efficiency (PCE) of 2.00, 1.72, and 1.06 % are achieved with CdSxSe1-x (obtained with S:Se = 0:4) alloyed QDs sensitized solar cells based on TiO2 NW/NT, TiO2 NW, and TiO2 NT architectures, respectively. The significant enhancement of power conversion efficiency obtained with the CdSxSe1-x/TiO2 NW/NT solar cell can be attributed to the extended absorption of light region tuned by CdSxSe1-x alloyed QDs and enlarged deposition of QDs and efficient electrons transport provided by TiO2 NW/NT architecture.