Moderate
Los Alamos researcher presents bright
idea
Researchers from the Laboratory are exploring methods for creating more electrically efficient organic light-emitting diodes - technology that could be used to create energy-efficient panels of light for use in buildings or homes.
Darryl Smith, of Electronic and Electrochemical Materials and Devices (MST-11), today presented ideas related to solving organic LED power efficiency problems at the 222nd national meeting of the American Chemical Society in Chicago. Smith's research focuses on the use of a chemical layer a mere molecule thick to help facilitate the flow of current from a power source into the self-assembled polymers that give organic LEDs their colorful glow.
Organic LEDs -- known as OLEDs -- currently are used in very thin, flat display screens, such as those in portable televisions, some vehicle dashboard readouts and in postage-stamp-sized data screens built into pilots' helmet visors. Arrays of OLEDs just one millimeter thick can display full-color moving or stationary pictures and graphics at extremely high resolution. Because OLEDs emit their own light and can be incorporated into arrays on very thin, flexible materials, they also could be used to fashion large, extremely thin panels for light sources in buildings or elsewhere.
"Organic light-emitting diodes show great promise in a number of applications," Smith said. "Their biggest drawback, however, is that they're not sufficiently efficient. Right now it takes a relatively large amount of electricity to make them work. If you can make OLEDs more energy efficient, then you potentially could create very bright, very long-lasting light sources that would be versatile, flexible and inexpensive to use."
A standard OLED consists of a transparent layer of an electrically conducting material, such as indium tin oxide, deposited on a transparent substrate. On top of this first conducting layer is another layer of organic polymer -- a chain of carbon-based molecules -- that emits light when excited by electrical current. A final conducting layer of material is deposited on top of the organic polymer layer. When voltage is applied to the two conducting layers, a current runs through the polymer layer and it emits photons, creating a light.
As simple as the process seems, it is not yet energy efficient. Because of the different chemical and physical properties of the conducting layers and the polymer layer, it often is difficult to create conditions that result in a smooth flow of current through the layers. As a result, more voltage must be applied to achieve the electric current required to generate photons from the organic polymer.
"Ideally what you want is to use the minimum amount of power to produce the light," Smith said.
Smith and Los Alamos colleague Ian Campbell of Neutron Science and Technology (P-23) have proven a method by which an intermediate chemical layer can be applied between a conducting layer and the polymer layer to achieve more efficient current flow. The process uses what nanotechnologists call a self-assembling monolayer to facilitate electrical flow between OLED layers.
The intermediate self-assembling monolayer comprises rows of molecules that line up in the same direction, like bristles on a brush, when applied to a substrate; inherent chemical properties of the molecule ensure proper alignment without external manipulation. By adding atoms at both ends of a monolayer molecule, the researchers developed a molecule that would anchor itself to the conducting layer while maintaining a distinct polarity across the entire molecule -- in essence giving the molecule charged ends like the poles of a bar magnet. The result is a molecular layer a few billionths of a meter thick that helps shuttle electrical charges between an OLED conducting layer and polymer layer.
The research still has a ways to progress. In order for OLEDs to be used as light sources, their efficiency probably must increase at least to the efficiency of existing fluorescent light bulbs. That means OLED efficiency must at least double based on comparisons of present OLEDs and fluorescent light bulbs.
Still, the gains in efficiency shown by use of a monolayer in OLED manufacturing has illuminated interest in the idea and feasibility of decorative panels of light that can be operated inexpensively by the consumer. With recent concerns over energy supplies and costs, the research is particularly relevant to the nation.
"I look at my role as providing a proof of concept for this type of technology," Smith said. "It will be up to industry to take these proofs of concept to create energy-saving devices that can be used by the public."
--James E. Rickman
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Use caution on roads to Mortandad Drilling crews started work on a water monitoring well in Technical Area 5 in Mortandad Canyon, and joggers, motorists and cyclists are urged to use caution and watch out for heavy equipment when traveling in the area. Crews are working on monitoring well R-13, the latest of 32 monitoring wells that will help scientists better understand hydrologic and geochemical processes on the Pajarito Plateau, and whether Laboratory-derived contaminants or other substances have made their way into local groundwater. Drilling work began last Tuesday and is expected to continue through mid September. Crews are working continuously seven days a week. Because of the work, large vehicles and heavy equipment may be traveling the dirt road to and from the site. The dirt road to the canyon floor begins where pavement on Pecos Drive ends. Joggers, cyclists and some motorists travel the dirt road during lunch hours and at other times of day. Because the road is narrow, John McCann of the Environmental Restoration Project (E-ER), leader of the drilling project, is asking people to travel cautiously and to be on the lookout for heavy equipment or work vehicles on the road and in the area. "There are a number of running trails on top of the canyon that people can use for exercise and we're urging people to use those trails or others instead of the road to the drilling site," McCann said, "If people insist on jogging or riding a bicycle on the road to the Mortandad Canyon floor, we are asking them to move off the road when vehicles are approaching. This will help us minimize the chances of accidents during the drilling period." --James E. Rickman |
Mentoring program hosts presentation Tuesday
on learning partnerships
The LANL Mentoring Program is hosting a presentation by Jodi Jaworski, vice president of The Mentoring Institute from 9 to 11 a.m. on Tuesday in the Physics Building Auditorium at Technical Area 3. The presentation is titled "Mentoring: Making the Most of A Learning Partnership," and is open to all Lab employees.
The presentation will focus on what makes a mentoring partnership an effective process for career development and what one can expect from mentoring.
Mentoring, formal and informal, is blossoming across the country as a method for accelerated learning and career advancement. To make the most of a partnership, it is imperative to understand what works, what does not, where the boundaries are located, and be familiar with techniques and strategies to achieve partnership potential, according to Training and Development (HR-6).
To register for the free session go to http://www.hr.lanl.gov/TD/Learning/index.stm online. Walk-ins also are welcome. Employees who register online and attend the session will receive credit for the course.
The LANL Mentoring Program is an initiative of the learning@lanl team to support career development through personalized contact with a mentor who has the skills, abilities, and experience Lab employees seek.
The Mentoring Institute is a subsidiary and corporate initiative of Big Brothers, Big Sisters out of St. Louis.
--Shelley Thompson
Green products expo is Tuesday
The Environmentally Preferable Products Expo is coming to the Laboratory from 10 a.m. to 2 p.m. Tuesday in the Otowi Building siderooms at Technical Area 3. Vendors will be displaying a wide array of environmentally preferable office products such as copy paper, tissue paper, folders, binders, notebooks, signs and desk organizers.
"Environmentally preferable products have a reduced impact on the environment or human health or both compared to competing products. They also may contain a higher percentage of renewable or post-consumer recycled material, be manufactured with fewer toxic chemicals, have reduced packaging, be fully recyclable and have the potential to never become waste," said Eleanor Chapman of the Environmental Stewardship Office (E-ESO), which is sponsoring the event.
Los Alamos must comply with Executive Order 13101: The Greening of the Government through Waste Prevention, Recycling, and Federal Acquisition. "The Lab is required by law to purchase environmentally preferable products whenever they are available competitively, at a comparable price and within a reasonable time frame," according to Chapman.
The Department of Energy goal is to purchase 100 percent of Environmental Protection Agency - designated products with recycled content. The exception is when the products are not available competitively at a reasonable price or don't meet performance standards. This goal is an Appendix F performance measure included in the Lab's contract with the University of California.
For more information on environmentally preferable products or the vendor expo, contact Chapman at 5-4651, or write to eleanorc@lanl.gov by electronic mail.
--John Bass
DOE Pulse highlights Energy Department laboratories
The latest issue of DOE Pulse is available online. Pulse is an online newsletter about accomplishments at the Department of Energy's national laboratories.The highlights are short, written to be interesting and very understandable.
In addition to the highlights, each issue features two longer articles -- one about a researcher and one about a multilabcollaborative effort.
Some of the headlines in this issue are: "Material for quantum computing" from Pacific Northwest National Laboratory, "Solving a mercury mystery" from Oak Ridge National Laboratory, "Answers in the sky" from National Energy Technology Laboratory, "Cooler cars" from National Renewable Energy Laboratory and "Quantum cryptography" from Los Alamos.
There also is a feature on Los Alamos and Sandia's New Mexico Nanoscience Alliance and a profile on Tammra Horning from Oak Ridge National Laboratory.
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Final week
of Route 66 incentive
