TAKING SOLAR TO ANOTHER LEVEL

Here's something to dream on while California's bureacracy makes the "milion solar roofs" vision vanish like a mirage in the Mojave Desert.

TR10: Nanocharging Solar; Arthur Nozik believes quantum-dot solar power could boost output in cheap photovoltaics
David Talbot, March 12, 2007 (MIT Technology Review)

WHO
Arthur Nozik, a senior research fellow at the National Renewable Energy Laboratory in Golden, CO, and Victor Klimov of Los Alamos National Laboratory in New Mexico, and their research teams

WHAT
The promise of cheap and abundant solar power remains unmet, largely because today's solar cells are so costly to make. A new solution may be in the offing: some chemists think that quantum dots--tiny crystals of semiconductors just a few nanometers wide--could at last make solar power cost-competitive with electricity from fossil fuels.

WHEN
- In the late 1990s, Nozik postulated that quantum dots of certain semiconductor materials could release two or more electrons when struck by high-energy photons. In 2004, Klimov provided the first experimental proof that Nozik was right; last year he showed that quantum dots of lead selenide could produce up to seven electrons per photon when exposed to high-energy ultraviolet light. Nozik's team soon demonstrated the effect in dots made of other semiconductors, such as lead sulfide and lead telluride.
- These experiments have not yet produced a material suitable for commercialization, but they do suggest that quantum dots could someday increase the efficiency of converting sunlight into electricity.

WHERE
National Renewable Energy Laboratory, Golden, CO, and Los Alamos National Laboratory, New Mexico

WHY
- Photovoltaic cells use semiconductors to convert light energy into electrical current. Silicon does this conversion fairly efficiently, but silicon cells are relatively expensive to manufacture. Other semiconductors, deposited as thin films, are cheaper but their efficiency doesn't compare to that of silicon.
- Quantum dots could increase the efficiency of converting sunlight into electricity. And since quantum dots can be made using simple chemical reactions, they could also make solar cells far less expensive.

QUOTES
- The project is a gamble, and Nozik readily admits that it might not pay off. Still, the enormous potential of the nanocrystals keeps him going.
- A commercial quantum-dot solar cell is many years away, assuming it's even possible. But if it is, it could help put our fossil-fuel days behind us.