A trio of researchers at North Dakota State University and the University of South Dakota have turned to computer modeling to help decide which of two competing materials should get its day in the sun as the nanoscale energy-harvesting technology of future solar panels -- quantum dots or nanowires.
Amorphous Silicon nanowire (yellow network) facilitates harvesting of solar energy in the form of a photon (wavy line). In the process of light absorption a pair of mobile charge carriers is created (red clouds depict an electron smeared in space, while the blue clouds visualize the so-called hole which is a positively charged carrier). The energy of their directed motion is then transformed into electricity. Electron and hole charge distributions are often located in different regions of space due to multiple structural defects in amorphous silicon nanowires.
Credit: A.Kryjevski, S.Kilina and D.Kilin/JRSE
Andrei Kryjevski and his colleagues, Dimitri Kilin and Svetlana Kilina, report in AIP Publishing's Journal of Renewable and Sustainable Energy that they used computational chemistry models to predict the electronic and optical properties of three types of nanoscale (billionth of a meter) silicon structures with a potential application for solar energy collection: a quantum dot, one-dimensional chains of quantum dots and a nanowire. The ability to absorb light is substantially enhanced in nanomaterials compared to those used in conventional semiconductors. Determining which form -- quantum dots or nanowire -- maximizes this advantage was the goal of the numerical experiment conducted by the three researchers.
"We used Density Functional Theory, a computational approach that allows us to predict electronic and optical properties that reflect how well the nanoparticles can absorb light, and how that effectiveness is affected by the interaction between quantum dots and the disorder in their structures," Kryjevski said. "This way, we can predict how quantum dots, quantum dot chains and nanowires will behave in real life even before they are synthesized and their working properties experimentally checked."
The simulations made by Kryjevski, Kilin and Kilina indicated that light absorption by silicon quantum dot chains significantly increases with increased interactions between the individual nanospheres in the chain. They also found that light absorption by quantum dot chains and nanowires depends strongly on how the structure is aligned in relation to the direction of the photons striking it. Finally, the researchers learned that the atomic structure disorder in the amorphous nanoparticles results in better light absorption at lower energies compared to crystalline-based nanomaterials.
"Based on our findings, we believe that putting the amorphous quantum dots in an array or merging them into a nanowire are the best assemblies for maximizing the efficiency of silicon nanomaterials to absorb light and transport charge throughout a photovoltaic system," Kryjevski said. "However, our study is only a first step in a comprehensive computational investigation of the properties of semiconductor quantum dot assemblies.
"The next steps are to build more realistic models, such as larger quantum dots with their surfaces covered by organic ligands and simulate the processes that occur in actual solar cells," he added.
The article, "Amorphous Silicon Nanomaterials: Quantum Dots Versus Nanowires" by Andrei Kryjevski, Dmitri Kilin and Svetlana Kilina, appears in the Journal of Renewable and Sustainable Energy. See: http://dx.doi.org/10.1063/1.4817728
ABOUT THE JOURNAL
The Journal of Renewable and Sustainable Energy is an interdisciplinary, peer-reviewed journal covering all areas of renewable and sustainable energy that apply to the physical science and engineering communities. See: http://jrse.aip.org
Jason Socrates Bardi | EurekAlert!
Team develops fast, cheap method to make supercapacitor electrodes
18.07.2017 | University of Washington
Magic off the cuff
11.07.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...
19.07.2017 | Event News
12.07.2017 | Event News
12.07.2017 | Event News
20.07.2017 | Information Technology
20.07.2017 | Materials Sciences
20.07.2017 | Physics and Astronomy