ORNL’s diverse capabilities span a broad range of scientific and engineering disciplines, enabling the Laboratory to explore fundamental science challenges and to carry out the research needed to accelerate the delivery of solutions to the marketplace. ORNL supports DOE’s national missions of:
- Scientific discovery - We assemble teams of experts from diverse backgrounds, equip them with powerful instruments and research facilities, and address compelling national problems;
- Clean energy - We deliver energy technology solutions for energy-efficient buildings, transportation, and manufacturing, and we study biological, environmental, and climate systems in order to develop new biofuels and bioproducts and to explore the impacts of climate change;
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ORNL supports these missions through leadership in four major areas of science and technology:
- Neutrons - We operate two of the world’s leading neutron sources, which enable scientists and engineers to gain new insights into materials and biological systems;
- Computing - We accelerate scientific discovery through modeling and simulation on powerful supercomputers, advance data-intensive science, and sustain US leadership in high-performance computing;
- Materials - We integrate basic and applied research to develop advanced materials for energy applications;
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Oak Ridge National Laboratory Postings
Mar 19, 2015 | Bing Huang, Hui-Xiong Deng, Hoonkyung Lee, Mina Yoon, Bobby G. Sumpter, Feng Liu, Sean C. Smith, Su-Huai Wei
Silicon is arguably the best electronic material, but it is not a good optoelectronic material. By employing first-principles calculations and the cluster-expansion approach, we discover that hydrogenated bilayer silicene (BS) shows promising potential as a new kind of optoelectronic material. Most significantly, hydrogenation converts the intrinsic BS, a strongly indirect semiconductor, into a direct-gap semiconductor with a widely tunable band gap. At low hydrogen concentrations, four ground states of single- and double sided hydrogenated BS are characterized by dipole-allowed direct (or quasidirect) band gaps in the desirable range from 1 to 1.5 eV, suitable for solar applications. At high hydrogen concentrations, three well-ordered double-sided hydrogenated BS structures exhibit direct (or quasidirect) band gaps in the color range of red, green, and blue, affording white light-emitting diodes. Our findings open opportunities to search for new silicon-based light-absorption and light-emitting materials for earth-abundant, high efficiency, optoelectronic applications.
Originally published by the American Physical Society...