A New Idea For Window Glass That Harvests Energy

What happens when you expose tellurite glass to femtosecond laser light? That’s the question that Gözden Torun at the Galatea Lab, Ecole Polytechnique Fédérale de Lausanne, in a collaboration with Tokyo Tech scientists, aimed to answer in her thesis work when she made the discovery. Its a discovery that may one day turn windows into single material light-harvesting and sensing devices and perhaps a new semiconductor material.

The physicists propose a novel way to create photoconductive circuits, where the circuit is directly patterned onto a glass surface with femtosecond laser light. The new technology may one day be useful for harvesting energy, while remaining transparent to light and using a single material.

The results have been published in PR Applied.

The scientists were interested in how the atoms in the tellurite glass would reorganize when exposed to fast pulses of high energy femtosecond laser light. They stumbled upon the formation of nanoscale tellurium and tellurium oxide crystals, both semiconducting materials etched into the glass, precisely where the glass had been exposed.

That was the eureka moment for the scientists, since a semiconducting material exposed to daylight may lead to the generation of electricity.

Yves Bellouard, who runs Ecole Polytechnique Fédérale de Lausanne’s (EPFL) Galatea Laboratory explained, “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. An interesting twist to the technique is that no additional materials are needed in the process. All you need is tellurite glass and a femtosecond laser to make an active photoconductive material.”

Using tellurite glass produced by colleagues at Tokyo Tech, the EPFL team brought their expertise in femtosecond laser technology to modify the glass and analyze the effect of the laser.

After exposing a simple line pattern on the surface of a tellurite glass 1 cm in diameter, Torun found that it could generate a current when exposing it to UV light and the visible spectrum, and this, reliably for months.

“It’s fantastic, we’re locally turning glass into a semiconductor using light,” exclaimed Yves Bellouard. “We’re essentially transforming materials into something else, perhaps approaching the dream of the alchemist!”

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One always enjoys the birth of a new technology with the “eureka!” and prognostications that accompany these newborns. While very few make it to mass market adulthood the experience and intellect tasking provides a culture and discipline to make even more ‘discoveries’. From which the progress of technologies move the technical wealth of humanity further into a brighter future.

There isn’t enough here to know how this will discovery will progress other than more testing for now. But tellurite glass suddenly got really interesting and the possibilities of a new semiconductor material could be immerse.

Or not. The journey of research and understanding is what makes it worthwhile for now and that is an important journey all by itself.

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