National Renewable Energy Laboratory
Computational Sciences
Nanoscale Material Design
Our Challenge
As part of the National Nanoscience Initiative, NREL's Scientific Computing Center is developing methods to design materials with desired properties at the atomic level. These properties include the "bandgap," which determines what portion of the solar spectrum a photovoltaic cell absorbs, and the "effective mass," which is an important measure of the ability of the cell to extract the energy it has absorbed.
Our Approach
To do so, we search a large space of possible atomic arrangements for one with desired properties. The electronic structure of each of a "population" of materials is computed, and the system guides the search toward a material with desired properties using a "genetic algorithm."
Our Results
Current applications, shown in the following movies, include semiconductor alloys and quantum dots.
AlGaAs Alloy (MOV 936 KB)
Progress in the search for an Al0.75 Ga0.25As alloy having minimum bandgap. The blue and red spheres represent aluminum and gallium atoms, respectively. The movie shows the system evolving toward the optimal structure, which is an ordered alloy known to metallurgists as "Luzonite."
CdSe Quantum Dot (MOV 961 KB)
Progress in the search for a CdSe quantum dot having maximum bandgap. The green and yellow spheres are cadmium and selenium, respectively. The initial spherical configuration has a minimum bandgap. In the search for a configuration with maximum bandgap, the system moves away from it and toward a more complex structure.
