Powerful laser pulses etch small patterns onto metal surfaces, so that they absorb a lot of light.
Not long ago, researchers presented an unsinkable piece of metal that even floated with holes on water. How did they manage this? They fired laser beams at a flat piece of metal to etch very small patterns onto the surface. These retain air and make the piece of metal water-repellent in this way. But the same method can also be used for other purposes. For example, for generating solar energy as efficiently as possible.
Solar collector
In the study, the researchers this time went in search of the most perfect solar collector (see box). A few years ago they already developed a way – again with laser beams – to make shiny metal pitch black. “But to make the perfect solar collector, we need more than just black metal,” says researcher Chunlei Guo. This pitch black metal, for example, caught light over a wide range of wavelengths. And so the researchers tried to figure out how to make a solar collector that selectively only absorbs light emitted by the sun.
What is a solar collector?
A solar collector is actually the brother of the solar panel. Both are used to generate energy from the sun. The only difference is that a solar collector converts sunlight into heat, while a solar panel converts sunlight into electricity. A solar collector often consists of a black plate that absorbs sun rays. Rooms or water can be heated in this way.
Laser pulses
The researchers decided to take their laser out of the cabinet again. They then irradiated metal surfaces with very short laser pulses. In this way they etched patterns on the metal on a micro and nanoscale. In the earlier study, the researchers already proved that this metal can make water repellent. But now they also show that thanks to this method the metal absorbs light very well. “Our laser technology can therefore change the properties of metal by applying structures to the surface,” Guo explains to Scientias.nl. “We adjusted the size and density to etch patterns so that we only absorb sun rays strongly. This surface not only improves the energy absorption of sunlight, but also reduces heat dissipation at other wavelengths. As a result, we have created a perfect metal solar collector for the first time. ”
Tungsten
In the research, the researchers experimented with different types of metals. For example, they let aluminum, copper, steel and tungsten pass through their hands. Tungsten is most commonly used as a thermal solar collector. But when tungsten was treated with the new technology and small nano-patterns were etched on it, it also appeared to absorb most of the sun’s rays. In fact, it improved efficiency by as much as 130 percent compared to untreated tungsten.
Improvement
According to the researchers, their new solar collector is a considerable improvement compared to what is already on the market. “Our collector converts solar energy into heat and generates electricity,” Guo says when asked. “Moreover, no other technology can turn metals into perfect solar collectors. Then often semiconductors are used instead of metals. “
Applications
According to the researcher, the new invention can be used for various commercial applications. “Consider, for example, the conversion of solar energy, the capture of lost heat, the removal of hot or cooling plates,” Guo sums up. Moreover, the same technology can also be used for better lamps. The researchers applied small micro patterns to a normal filament made from tungsten. And the result was convincing. The incandescent lamp gave more light with the same energy consumption.
The findings from the study show that the application of very small micro patterns to metals entails an expanse of possibilities and applications. And that is interesting, because who knows what else is looming on the horizon. We therefore keep a close eye on Guo’s laboratory!