Solar-sensitive nano-particles that could lead to cheaper and more flexible solar cells

Scientists at the University of Toronto has designed and tested a new class of solar-sensitive nano-particles that could lead to cheaper and more flexible solar cells.

The researchers Zhijun Ning (post-doctoral researcher)  and Professor Ted Sargent describe the new technology as being made up of solid and stable light-sensitive nano-particles called colloidal quantum dots that are better gas sensors, infra-red lasers and infra-red light emitting diodes.

How does it work?

Tiny colloidal quantum dots collect sunlight using two separate types of semiconductors.

The issue has been that these materials loose their properties when exposed to air. But these researchers demonstrated that their nano-particles not only retained their properties, but also had a boost of efficiency of light absorption, and displayed other properties that make them suitable for use in optoelectronic devices (weather satellites, remote controllers, satellite communication, or pollution detectors) — that capitalize on the best properties of both light and electricity.

“This is a material innovation, that’s the first part, and with this new material we can build new device structures,” said Ning. “Iodide is almost a perfect ligand for these quantum solar cells with both high efficiency and air stability—no one has shown that before.”

This new ‘hybrid’ material achieved 8% solar power conversion efficiency—the most effective result yet. This opens up a wide range of opportunities for the application of solar cell technology such as in inks for painting or printing onto thin, flexible surfaces, such as roofing shingles, dramatically lowering the cost and accessibility of solar power for millions of people.

“The field of colloidal quantum dot photovoltaics requires continued improvement in absolute performance, or power conversion efficiency,” said Sargent. “The field has moved fast, and keeps moving fast, but we need to work toward bringing performance to commercially compelling levels.”

Reference:
1) New class of nanoparticle brings cheaper, lighter solar cells outdoors — University of Toronto
2) Zhijun Ning et al: Air-stable n-type colloidal quantum dot solids. Nature Materials, 2014; DOI: 10.1038/nmat4007