Sandia Researchers Use Quantum Dots As a New Approach to White, Blue Solid-State Lighting
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Sandia researchers use quantum dots as a new approach to white, blue solid-state lighting By Chris Burroughs In a different approach to creating white light several Sandia researchers have developed the first solid-state white light-emitting device using quantum dots. In the future, the use of quantum dots as light-emitting phosphors may represent a major application of nano- technology. “Understanding the physics of lumines- cence at the nanoscale and applying this knowl- edge to develop quantum dot-based light sources is the focus of this work,” says Lauren Rohwer (1745), principal investigator. “Highly efficient, low-cost quantum dot-based lighting would rep- resent a revolution in lighting technology through nanoscience.” The project is part of Sandia’s internally funded Laboratory Directed Research and Development (LDRD) Solid State Lighting Grand Challenge. The approach is based on encapsulating semiconductor quantum dots — nanoparticles approximately one billionth of a meter in size — and engineering their surfaces so they efficiently emit visible light when excited by near-ultraviolet (UV) light-emitting diodes (LEDs). The quantum dots strongly absorb light in the near-UV range and re-emit visible light that has its color determined by both their size (Continued on page 4) NEW APPROACH TO SOLID-STATE LIGHTING — Lauren Rohwer is the principal investigator of a research team developing the first solid-state white light-emitting device using quantum dots. (Photo by Randy Montoya) Employees, teams receive recognition During the recent Sandia Employee Recognition Night, 66 indi- Vol. 55, No. 14 July 11, 2003 viduals and 57 Managed by Lockheed Martin for the National Nuclear Security Administration teams were honored for exceptional Sandia energy security team works to make achievements. The program carries on a tradi- tion that since 1994 has honored Sandians key military bases ‘grid-free’ in the future for outstanding service rendered to the Labs By Will Keener uted Energy Resources Dept. 6251. and the nation. Read about the winning In the months since, the Army has asked teams and see pictures of the individual recip- Dave Menicucci thinks that it was Mother Sandia to look at three pilot forts and make rec- ients on pages 6 through 10. Nature as terrorist who ultimately pushed the ommendations for an optimal mix of generating Department of Defense toward improving its technologies to help them achieve energy secu- energy infrastructure security. He knows Septem- rity. In addition, a US Marines Corps base is also ber 11, 2001, had a role as well. “Prior to that very interested in the Sandia approach, Dave Paul Robinson discusses date, most experts felt border security was suffi- reports. They want to bring their generation cient and concern about infrastructure security inside their fences and distribute it around so management changes at domestic military bases was minimal,” Dave that there won’t be any one clear target. Sandia is says. After September 11, that changed. working to help them develop a “grid-free” plan On June 26 Sandia President and And then in May 2002, a fierce wildfire cut that will be in place by 2007. Labs Director C. Paul Robinson sent a both feeder lines supplying a remote military base Bill Black of Solar Technologies Dept. 6218 is message electronically to all Labs with power. Completely off the grid, the base went project manager for several of the military energy employees regarding several major to its back-up mode. Although some facilities were security projects and has visited three pilot Army changes in management announced a equipped with diesel generators, officials soon real- bases. “This is a natural extension of our work with few days earlier. Last week Sandia pro- ized the base would need more fuel for the signifi- nuclear weapons security,” he says. “It builds on vided to local news media photocopies of cant amount of time needed to restore grid power. what Sandia has done with dams, transmission a 29-page summary of the “Bay report,” But by the time they turned attention to this prob- lines, and other vulnerability assessments.” the independent internal investigation lem, the generators had run out of diesel. The Sandia goal is not just to assess and Paul commissioned last August coordi- The result: the base was at a diminished implement distributed energy resources for the state of readiness for 16 hours. Costs attributed three pilot bases, but to develop a methodology nated by Norman Bay, a former US attor- to the downtime were approximately $3 mil- that can be used by others as well. “We want to ney in New Mexico and assistant profes- lion. True, this strike was from nature, but it be able to say, ‘Here’s a workbook you can apply sor at the University of New Mexico illustrates how effective a coordinated attempt to any military base to provide combined heat School of Law. Read the full text of Paul’s at sabotage could be. and power systems,’” Bill says. Nonmilitary message on page 5. “This really raised awareness as to how vulner- applications, such as support for emergency ser- able these bases are,” says Dave, project lead and vices in smaller communities, also are a possibil- staff member in Energy Infrastructure and Distrib- ity for this approach, he says. The Marines have asked Sandia to integrate a 7.6-megawatt cogeneration power plant with a one- megawatt photovoltaic system. “They want a plan Brotherhood of the Bomb author Herken to show how they can get off the grid if they need 3 details establishment of ‘Rad Lab’ to and still have the mission capabilities they need to respond,” says Dave. The Sandia approach will be to provide solu- tions that are based on full-time generation by a dis- Sandia helps 310 state businesses in tributed energy system, which can be isolated for 12 2002 in New Mexico tax-credit program security reasons when the grid goes away. “This is (Continued on page 4) New-hire John Bowers What’s what honored with alma mater’s Despite the discomfort, anxiety, embarrassment, frustration, Founders’ Award angst, and a whole range of other emotions Sandians have felt about the disclosure of problems with the lab’s security over the past few months, Sandia new-hire John Bowers (14011) was we can all be proud of the way those difficulties have been handled. honored recently by Binghamton University’s Rather than denying that problems existed — or worse, ignoring Watson School of Engineering and Applied Sci- them — Labs Director Paul Robinson commissioned an outside independent ence with its Founders’ Award. In recognition of the legacy of the Watson School founders, the review and, as we learned most recently, dealt with the problems pointed award is given to those out in that review, then publicly acknowledged them. who have shown the As we’ve learned from the Exxon Valdez and other disasters, few same type of vision and organizations handle problems appropriately when the pressure’s on. commitment to the Sandia is an obvious exception. Read more about it on page 5. Watson School since its * * * formation in 1983. Be sure to have a look at this year’s Employee Recognition Award John recently winners, beginning on page 6. All of them — individuals and teams — started a new position turned in terrific performances to be considered. They were feted at the as program engineer in Marriott Pyramid Hotel in Albuquerque, which is pretty good recognition Sandia’s Concurrent in itself. Design and Manufac- turing Program, where JOHN BOWERS Congratulations to all the winners, and good work. he will help manage * * * programs for the nuclear weapons complex and You may have heard a funny sound earlier this week. It was scores production realization enterprise. of folks around the lab sucking in their breath in shock when they Prior to coming to Sandia, he worked in both learned that lab-wide network and Central Computer Services would be the military and private sector. He earned his unavailable from late this Saturday until Monday morning. degree in civil engineering from the Coast Guard Withdrawal, you know. Academy and worked as a civil engineer for the Facilities is doing major cooling system upgrades in Bldg. 880 and Coast Guard before moving to Oneonta, N.Y., to several other buildings around it, which means e-mail and all other work as manager of Custom Electronics’ engineer- corporate and scientific computing services will be turned off. Can you ing department. While there he was responsible imagine? No e-mail? No weekend work? for new product development and design, and industrial, manufacturing and facilities engineer- Woops!. There it goes again — that anguished sucking sound! ing management. * * * Returning to school, Bowers became the first Right off the top of your head, you might think the most common graduate from the Watson School’s industrial topic of discussion and debate around the lab is LED lighting, or maybe a engineering discipline when he earned his MS prediction of the next Z machine triumph, or maybe some of the out-there degree in 1989. Since then, he has put his knowl- ideas hatched in the Advanced Concepts Group. edge and experience to use as an adjunct instruc- Well, maybe in your group. But in ours — and I suspect in a lot of tor and brought the small business perspective to others — it’s the battle of wills pitting the donut dudes against the both the Watson School Advisory Committee and bagel bunch. You know, on Friday (or maybe some other day in your group) the Industrial Engineering Advisory Committee. somebody’s supposed to bring in a morning gorging. And the day before, the factions line up and plead their preferences.