Quantum Dots may mean Solar Panels on House Windows

As scientists learn more about the the properties of quantum dots, their applications in everything from digital displays to renewable energy are becoming increasingly apparent.

New research out of Los Alamos National Laboratory in New Mexico - done in collaboration with scientists from the University of Milano-Bicocca in Italy -reveals the light-emitting properties of quantum dots can be applied in solar energy by more efficiently harvesting sunlight. Ultimately, the team believes this could lead to the use of quantum dots in house windows, even, that double as solar panels.

"The key accomplishment is the demonstration of large-area luminescent solar concentrators that use a new generation of specially engineered quantum dots," said lead researcher Victor Klimov of the Center for Advanced Solar Photophysics at Los Alamos.

Quantum dots are ultra-small bits of semiconductor matter scientists can synthesize with nearly atomic precision. By varying their dimensions, scientists can "tune" their color, allowing for emission efficiencies close to 100 percent. This has recently become the basis of quantum dot displays, used in products like the newest generation of the Kindle Fire e-reader.

These properties also make quantum dots attractive for projects such as a luminescent solar concentrator (LSC), which is a "light-harvesting antenna, which concentrates solar radiation collected from a large area onto a much smaller solar cell, and this increases its power output," said Klimov.

Sergio Brovelli, who worked at Los Alamos before joining the faculty at the University of Milano-Bicocca, was excited by the practical applications of combining the two technologies.

"LSCs are especially attractive because, in addition to gains in efficiency, they can enable new, interesting concepts such as photovoltaic windows that can transform house facades into large-area energy generation units," he said.

Originally, scientists ran into a problem with the highly efficient quantum dots' re-absorption rate, which led to significant light losses on account of the quantum dots gathering back in some of the light they produce.

This problem was overcome by separating the light-absorbing and light-emitting functions in two different parts of the quantum dots' nanostructure. The resulting large spectral shift of emission, relative to absorption, greatly reduces losses to re-absorption.

The group's research originally appeared in the journal Nature Photonics.