What happens when tellurite glass is exposed to a femtosecond laser? Gözden Torun of the Galatea Laboratory at the École Polytechnique Fédérale de Lausanne (EPFL), in collaboration with scientists from the Tokyo Institute of Technology (TIT), attempted to answer this question in her dissertation work, and her discovery may one day turn windows into single-material light-harvesting and sensing devices. The research was published in a recent issue of Physical Review Applied.
By using a femtosecond laser to etch semiconductor patterns, tellurite glass was transformed into a "transparent" light energy collector.
Scientists interested in how atoms in tellurite glass reorganize when exposed to rapid pulses of high-energy femtosecond lasers stumbled upon the formation of nanoscale crystals of tellurium and tellurium oxide, both semiconducting materials etched into the glass at the precise locations where the glass was exposed. This was a bright idea for the scientists, as semiconductor materials exposed to sunlight could lead to power generation.
Tellurium is a semiconductor, and based on this discovery, we wondered if it was possible to write durable patterns on the surface of tellurite glass that could reliably induce an electric current when exposed to light, and the answer was yes," explains Yves Bellouard, head of EPFL's Galatea laboratory. An interesting variation on this technique is that no additional materials are needed for the process. All you need is tellurite glass and a femtosecond laser to create an active photoconductive material."
Using tellurite glass produced by colleagues at the Tokyo Institute of Technology, the team from the École Polytechnique Fédérale de Lausanne used their expertise in femtosecond laser technology to modify the glass and analyze the effects of the laser. After exposing a simple pattern of lines on the surface of a 1-centimeter-diameter piece of tellurite glass, Torun found that when exposed to the ultraviolet and visible spectrums, it could generate an electric current that could last for months.
Yves Bellois said, "It's fantastic, we're using light to turn glass into semiconductors. We are basically transforming materials into other substances and are perhaps approaching the alchemist's dream."
