The US Department of Energy's (DoE) Office of Energy Efficiency and Renewable Energy will spend nearly $5 million for solid-state lighting (SSL) research in nanotechnology, it was announced last week. The research will be conducted by DoE's Sandia, Oak Ridge, Los Alamos and Argonne national laboratories, with Sandia's four projects receiving approximately half of the funds.

DOE Secretary Samuel W. Bodman announced the selection of the seven projects, saying SSL has the potential to more than double the efficiency of general lighting systems, reducing overall US energy consumption and saving consumers money.

By 2025, DoE expects to develop advanced SSL technologies that are 50 percent more efficient, last longer and are cost-competitive compared to conventional lighting technologies that accurately reproduce sunlight. This SSL nanotechnology research will include scientific efforts to gain more comprehensive knowledge and understanding of nanometer-scale phenomena for the specific application of SSL.

Unlike incandescent and fluorescent lamps, solid-state lighting creates light without producing heat. A semiconducting material converts electricity directly into light, which maximizes the light's energy efficiency. Solid-state lighting includes a variety of light-producing semiconductor devices and includes LEDs and organic LEDs (OLEDs). LEDs are found in all kinds of devices; they form numbers on digital clocks, light up watches and transmit information from remote controls. They can also be seen in brake lights, traffic signals and exit signs. OLED technology is more commonly used commercially, for example in small screens for mobile phones, portable digital music players and digital cameras.

With its $2.6 million in funding, Albuquerque, N.M.-based Sandia National Laboratories will create white LEDs by developing blends of oxide nanophosphors and semiconductor quantum dots in encapsulants. The lab will also develop a high-efficiency LED structure that takes advantage of surface plasmons -- electromagnetic waves at the interface between a metal and dielectric (semiconductor) -- that can improve light emission by as much as 90 times in specialized, optically pumped LED structures. This project aims to create electrically injected devices which benefit from the plasmon effect. Other Sandia projects will work to make decreased defect-density GaN substrates to enable higher efficiency LED devices and develop MOCVD (metallorganic chemical vapor deposition) growth methods to further reduce GaN dislocation densities on sapphire, which make devices less efficient.

With its $600,000 award, Oak Ridge National Laboratory in Tennessee will address two challenges whose solution is crucial to improve the efficiency of OLEDs: enhanced internal quantum efficiency via control over the singlet/triplet ratio, and enhanced carrier transport through poorly conducting organic materials by using carbon nanotubes as low-cost transparent electrodes.

Los Alamos National Laboratory in New Mexico will spend its $800,000 to establish a new class of high-efficiency, low-voltage, stable hybrid OLEDs for general illumination. This new class of hybrid OLEDs will be fabricated from organic/inorganic nanoparticle composite semiconductors.

At Argonne National Laboratory, located just outside Chicago, researchers will work with transparent conductive oxides (TCOs), critical for OLED device efficiency. This project proposes an innovative transparent conducting layer consisting of a self-assembled network of conducting particles, the nanometer dimensions and large open area ratios of which make them much more transparent for a given electrical conductivity than conventional TCOs. The project funding is $956,100.

For more information, visit: www.doe.gov