A new technology, which creates a rainbow of optical colors with ultra-thin layers of silicon, has been recently demonstrated by a research group at the University of Alabama in Huntsville (UAH).
Vibrant optical colors are generated from ultra-thin single layer silicon films deposited on a thin aluminum film surface with a low cost manufacturing process. The optical colors are controlled by the thickness of silicon films.
Michael Mercier / UAH
Doctoral student Seyed Sadreddin Mirshafieyan and Dr. Junpeng Guo in Dr. Guo’s lab with a disc showing a rainbow of optical colors created with ultra-thin layers of silicon. The quarter in the center of the disc has also been coated.
The thickness of the silicon films ranges from 20 to 200 nanometers for creating different colors. For reference, 100 nanometers is about 1/1000 of the thickness of a single sheet of paper.
One nanometer is about two atomic layers of silicon. The silicon color coating process can be applied on almost any material surface. In fact, the team has colored quarters, turning them into a variety of colors.
“The reason we chose silicon is not only because silicon is a low cost material and has been widely used in electronics industry, but also most importantly, silicon is an indirect bandgap semiconductor material with both high index of refraction and low optical absorption in the visible spectrum.
The combination of high index of refraction and low absorption enables strong optical wave interference inside ultra-thin silicon films, a physical process that results in colors,” says Dr. Junpeng Guo, professor of electrical engineering and optics, who has published the result with his graduate student, Seyed Sadreddin Mirshafieyan, in a recent issue of Optics Express, vol. 22, issue 25, p. 31545 (2014).
Colors seen from flowers in nature and chemical materials are caused by wavelength selective light absorption in organic molecules. Currently, colors on computer and iPhone screens come from dye materials pre-placed on the pixels. Colors of chemical dyes only work in a limited range of temperatures around room temperature. The demonstrated silicon colors can sustain high temperatures and harsh environment.
“The reason these colors are so vibrant, is because one wavelength of light is completely absorbed,” explains Dr. Guo, while his student holds a collection of color samples. “And the colors are very durable. A lot of colors you see in nature are due to wavelength selective light absorption in organic molecules which cannot withstand high temperatures,” he says. Ultraviolet light destroys organic dye molecules over time, leading to color change and fading.
The new technology may hold promise for many applications such as for jewelry, automotive interior trim, aviation, signage, colored keypads, electronics and wearable displays.
Jim Steele | newswise
A big nano boost for solar cells
18.01.2017 | Kyoto University and Osaka Gas effort doubles current efficiencies
Multiregional brain on a chip
16.01.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
19.01.2017 | Physics and Astronomy
19.01.2017 | Health and Medicine
19.01.2017 | Ecology, The Environment and Conservation