More juice from the sun: LANL science fuels new photophysics energy center

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By Roger Snodgrass

In early April, when Energy Secretary Steven Chu visited Los Alamos National Laboratory, Victor Klimov briefed him on research about a project for improving solar cells.

As Chu moved slowly through a gallery of scientific posters especially selected for his introductory moments at the lab, he listened intently to Klimov’s overview and immediately began asking questions about his findings.

“He was really interested,” Klimov said in an interview this week. “That impressed me that he knew what we were doing.”

This week, Klimov got a call from the Department of Energy with some exciting news.

A proposal that he and colleagues at LANL had submitted along with collaborators from the National Renewable Energy Laboratory in Golden Colorado and several other research institutions was about to be funded.

More, the project to establish a Center for Advanced Solar Photophysics was not only going to be funded, it was launched on a five-year voyage.

“That’s probably the longest program we’ve ever had,” Klimov said.

In fact, LANL will host two and participate in another five of the nation’s 46 new Energy Frontier Research Centers, a concerted effort by the Department of Energy to sweep aside scientific and technical obstacles blocking the way to a clean and sustainable energy future.

Another project at LANL, “Extreme Environment Tolerant Materials via Atomic Scale Design of Interfaces,” is related to the lab’s signature facility, a concept known as MaRIE. That project will be involved in developing materials at the limits of extreme conditions.

The full breakout energy project with a $777 million commitment altogether over the next five years, was announced in conjunction with President Obama’s speech Monday at the National Academy of Sciences, when he declared his intention to invest more than 3 percent of national Gross Domestic Product in research and development.

“This represents the largest commitment to scientific research and innovation in history,” Obama said. “Just think what this will allow us to accomplish.”

The first items on his list were “solar cells as cheap as paint (and) green buildings that produce all the energy they consume.”

That’s a tall order, but for Klimov, the growing demands for clean energy can only be met through revolutionary change, which he accepts as “one of the biggest fundamental challenges of modern science.”

A LANL Fellow, with a Doctor of Science degree from Moscow State University in 1993, Klimov has led the “Softmatter Nanotechnology and Advanced Spectroscopy” team in the Chemistry Division in recent years.

Among his research highlights during this period has been the rapid evolution of a new type of laser technology based on nanocrystal quantum dots, or “ultra-small bits of semiconductor material,” as he described them in a paper in “Los Alamos Science” in 2003.

Because these dots are made up of only a few hundred to a few thousand atoms, he wrote, “these specks of matter exhibit a mix of solid state and atomic properties.”

Nanocrystal quantum dots, he goes on to say, “can be viewed as tunable artificial atoms with properties that can be engineered to suit either the needs of a certain experiment or a specific technological application.”

Among current developments, Klimov has been working on a process known as carrier multiplication, by which a solar cell made of nanocrystal quantum dots can generate more than the usual single electron that contributes to the electric current when struck by a photon.

“How can we maximize the number of electrons produced per absorbed photon? How can we efficiently extract the generated charges from the quantum dot?” Klimov asks.  “More and more groups are getting interested in this effect. This collective effort should help us to answer these questions.”

Klimov further notes that the ability to improve efficiency by the usual route of engineering has a limited upside.

But, he believes, by coming up with new physical principles for solar energy conversion and by learning how to exploit the unique properties of nanostructured materials, we can more efficiently manipulate photons and control the dynamical behavior of electrons.

“Nanostructures can help us harvest more light than silicon,” he concludes.

To be sure, there are challenges, including understanding the physics that underlies the process of carrier multiplication and the factors that control its efficiency. However, a five-year program and a bunch of ideas to explore should go a long way to resolving these challenges.

“We are very excited by the opportunity ahead,” Klimov said.