The application of semiconductor nanomaterials in photoanodes

Compared to bulk materials, semiconductor nanomaterials as photoanodes can offer a larger surface area for dye adsorption, contributing to optical absorption and leading to an improvement in the solar cell conversion efficiency. As photoelectrode materials in DSCs, the semiconductor nanostructures are usually classified into two types: (1) nanoparticles, which offer large surface area to photoanodes for dye-adsorption, however have recombination problem due to the existence of considerable grain boundaries in the film. To settle this issue, core-shell structure derived from the nanoparticles by forming a coating layer has been developed and applied to DSCs with a consideration of suppressing the interfacial charge recombination, while this kind of structure has been proved to be less effective and lack of consistency and reproducibility; (2) one-dimensional nanostructures such as nanowires and nanotubes, which are advantageous in providing direct pathways for electron transport much faster than in the nanoparticle film, however face drawback of insufficient internal surface area of the photoelectrode film, leading to relatively low conversion efficiency (Zhang & Cao, 2011). This section aims to demonstrate semiconductor nanomaterials as photoanodes, including nanoparticles, nanowires and nanotubes.