Conformal Filling of TiO₂ Nanotubes with Dense M_xS_y Films for 3D Heterojunctions: The Anion Effect

Abstract

It is appealing to fill up TiO 2 nanotube arrays with other semiconductors to form three-dimensional heterojunctions of interdigitated feature. This benefits from the large interfacial area for rapid charge separation and the ordered vertical channels for oriented charge transport. However, it remains a great challenge to fill the nanotubes with dense films and more importantly in a conformal manner. In this study, the TiO 2 nanotubes are conformally filled with ZnS by successive ionic layer adsorption and reaction. The ZnS exists in the form of either discrete nanoparticles or dense films when using nitrate or acetate precursor solutions, respectively. This is attributed to the hydrolysis process of the acetates in aqueous solutions, which releases extra hydroxyl ions beneficial to film formation. The CuS/TiO 2 heterojunctions, resulted from ZnS dense films, show better rectifying behaviors in view of the interdigitated structure. Such a conformal filling process with dense films can also be used to form other M x S y /TiO 2 bulk heterojunctions toward applications in optoelectronics, photovoltaics, photocatalysis, and so on.[a] X.

Printed single-walled carbon-nanotubes-based counter electrodes for dye-sensitized solar cells with copper-based redox mediators

“…Dye-sensitized solar cells (DSSCs) have been intensely investigated for more than a decade by employing numerous alternative materials, such as novel semiconducting oxides, novel dyes, redox mediators and catalysts that were compared to the traditional ones [1][2][3][4][5][6][7][8]. As a result, the solar-to-electrical conversion efficiencies for lab-sized DSSCs has recently crossed over 14%, which was achieved via employing alternative redox mediators based on cobalt complexes combined with a co-photosensitized photoelectrodes with two alternative dyes: ADEKA-1 (alkoxysilyl-anchor dye) and LEG4 (carboxy-anchor organic dye) [9].…”