Femtosecond lasers are making their mark in the material science sphere with solar technology that enables glass to be turned into a semiconductor. It’s a remarkable breakthrough in light harvesting with exciting implications for renewable energy, considering the accessibility and prevalence of clear glass in the world. For now, the innovative concept is brand-new, but the potential is so vast that researchers are excited to take the next step in making the tech accessible on a broader scale.

Glass could become an efficient energy-harvesting solar panel

Scientists working under a collaboration between the Galatea Laboratory at the Ecole Polytechnique Federale de Lausanne (EPFL) and a team from the Tokyo Institute of Technology (Tokyo Tech) made a remarkable discovery when they exposed tellurite glass to femtosecond laser light.

The study is led by Gozden Torun at EPFL and revolves around her thesis, which explores the effects of ultra-short femtosecond laser light pulses on the atoms in tellurite glass. These pulses create nanoscale patterns of tellurium and tellurium-oxide crystals in the glass. The crystals are semiconductive and form at the exact point where the laser meets the glass.

The concept is simple, only tellurite glass and a femtosecond laser are needed

The most significant discovery was the realization that the embedded crystals could potentially generate electricity when exposed to sunlight. Yves Bellouard, who leads the Galatea Laboratory at EPFL, explained the concept:

“Tellurium being semiconducting, based on this finding we wondered if it would be possible to write durable patterns on the tellurite glass surface that could reliably induce electricity when exposed to light, and the answer is yes.”

In the past, photoconductive surfaces have needed the fusion of multiple materials to function, making the production process complicated and costly. But this discovery involves only two components, the specialized glass and laser, making the process of turning the glass into an active photoconductive surface efficient and simple. The end result is simple, too: an electrical current that’s produced under exposure to light.

This breakthrough in tellurite and laser light is not the only innovation gathering attention in the renewable energy sector. Solar panels are set to get much cheaper soon with the discovery of an alternative material to platinum, which goes for around $1,500 an ounce.

The EPFL and Tokyo Tech experiment shows promising results

The team of experts from Tokyo Tech was charged with producing the specialized tellurite glass material needed for the EPFL to apply their femtosecond laser technology to modify the structure of the glass and analyze its photoconductive properties.

After etching a simple line pattern onto a one-centimeter-diameter section of tellurite glass, Gozden Torun’s experiments showed encouraging results. She observed that it could generate a current under UV light and the visible spectrum, and this capability was maintained reliably for months.

Yves Bellouard of EPFL reported that the results are “fantastic,” referring to the ability to turn glass into a semiconductor using light. He described the nature of the team’s work as “transformative” and likened the leap in science to the “dream of the alchemist” where materials are transformed into new forms with enriched properties.

Glass has a role to play in energy harvesting and sensor technology

It’s clear that the development in material science holds massive potential for the future of renewable energy harvesting. The applications extend to sensing technology as well, opening another avenue for development and innovation when considering that windows and other glass structures could be transformed into light harvesters or sensors in a simple, durable process.

Scientists at the University of Oxford are working on a different kind of technology that can turn walls, cars, and other objects into energy-harvesting structures with a flexible, ultra-thin solar cell material that delivers a 27% conversion efficiency.