BCCMS  /  Events  /  2010  /  CECAM Titania  /  Description

Description

Description/Objectives

TiO2, titania, is a crystalline oxide with a wide band gap and has been used as white pigment for a long time. It is also well known as a photocatalyst for water and air purification, and hydrogen production for use in fuel cells. In fact, doped TiO2 can also be used for hydrogen storage. Nanostructuring of this material is relatively easy and greatly enhances the efficiency in all these applications. Nanocrystalline layers are also used in electrochemical solar cells. Although rarely stressed, all these applications are based on the semiconducting properties of TiO2. Still, in electronics, titania was considered only as a dielectric, even though it’s self-doping property is being utilized in chemical gas sensors. In photovoltaic and optoelectronic applications it was often used as antireflection coating, but now it is being considered – with suitable doping – also as electron emission material or transparent conductive oxide. Doping can lead to room temperature ferromagnetism in TiO2, with promises for application in spintronics as a dilute magnetic semiconductor. Considering the multifunctionality of this “undercover” semiconductor, it is quite surprising that very little research has been directed towards fundamental semiconductor physics in this material. The reason for that on the experimental side was the difficulty of growing good quality single crystals, while standard methods of theory failed already at the description of the basic intrinsic defects. In addition, calculations with ab initio methods on nanostructures are prohibitively expensive for this material in case of most practical applications. In the last couple of years, with the advancements in density functional theory (DFT), like the spread of hybrid functionals and affordable many-body perturbation schemes for bulk calculation, as well as in semiempirical DFT methods, like DFTB, for the calculation of nanoclusters, the interest and capabilities have increased on part of the theory for the many applications of TiO2. We believe that it is time to have a workshop where leading theoretical groups get the chance of synchronizing their activities, and – even more importantly – to intensify their interaction with experimental research. The purpose of the suggested workshop is to bring together the leading theoretical groups working on various facets of TiO2, and recognized experimentalists who would expose the state-of-the-art in the various applications of TiO2. [more]

On the computational side, the workshop will combine two major directions:

 

i) high level ab initio methods applied to study defects and doping in the bulk

• Hybrid functional

• LDA + U

• Quasiparticle GW-approach

 

ii) surface structure and reactions at surfaces, photo-catalytic properties

• surface electronic structure, sub-suface defects

• surface reactions, photocatalysis

• time-dependent computational approaches

 

iii) various approaches investigating application-relevant properties of

low-dimensional nanostructures, including transport

• Dye sensitized solar cells, transient charge separation, transport

• Structure and properties of nano – particles/wires/rods/tubes

• TD-DFT approach, non-adiabatic MD

 

On the experimental side, all major application area of TiO2 shall be represented by an invited talk.