Designing Materials for Optoelectronics and Energy Applications
A prerequisite towards the design of novel materials in the fields of energy efficient optoelectronics, power electronics, catalysis, or superconductivity, is to understand, describe and predict the complex interplay between their structural, thermodynamic, magnetic, optoelectronic and electronic properties. Apart from bulk, interfaces (solid-solid, solid-liquid, and solid-gas) and surfaces, both at the nano- and the micro-meter scales, are of paramount importance in the design and the properties of these materials. Density functional theory calculations constitute the working horse in addressing and exploring the aforementioned interplay.
We use ab initio based molecular dynamics simulations to understand the thermodynamic driving forces triggering electrochemical reactions that involve hydrogen adsorption on Pt electrodes to gain fundamental understanding of processes at solid/liquid interfaces and aid the design of better electrocatalysts.
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Optoelectronic devices allow for the direct conversion of light and electrical energy. The performance of such optoelectronic devices is limited by losses due to non-radiative recombination. We have looked at the solar cell material Cu(In,Ga)Se
2. We identified not only an effective recombination pathway at high Ga contents involving configuration changes of Ga or In anti-sites, but also extended the charge corrections to the computation of configuration coordinate diagrams.
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The thermodynamic stability of computationally designed multicomponent compounds against decomposition into structures with less favorable properties is often unclear. In this project, we have used sophisticated finite temperature
ab initio methods to determine the relative phase stabilities of promising Ce-Fe-Ti hard-magnetic materials.
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Iron oxides and hydroxides of variable stoichiometry occur at the essential stages of iron ore reduction and ferrous metal corrosion (rusting). We aim at building up a fundamental understanding of how the ions (Fe
2+, Fe
3+, O
2-, OH
-) may arrange and rearrange to achieve such a broad composition range, in order to optimize the conditions to improve reduction processes and prevent corrosion.
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Using technologically interesting examples, such as wurtzite surfaces, we develop a robust passivation scheme for density-functional-theory surface calculations of materials exhibiting spontaneous polarization. The novel approach enables computationally efficient and accurate surface electronic structure calculations.
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We study the impurity incorporation mechanisms in metallic nano-aerogels is expected to identify routes to the targeted design of specimens with desired concentrations of impurities.
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