14 DAY TRIAL // Using a wet chemistry process, a collaboration of experts in the United States is now able to manufacture nanometer-sized semiconductor particles called colloidal quantum dots. These nanoscale structures can produce either red, green or blue light.
This is a remarkable achievement, primarily because lasers available for consumer electronics today are only capable of producing a single color. Therefore, you need to have three lasers side-by-side, each with its unique makeup and constituent material, in order to form a single pixel.
What experts from the Brown University and QD Vision, Inc. demonstrated has never been proven before, and could signify an important step forward in designing new types of lasers and displays for various electronic equipment.
In essence, these colloidal quantum dots are nanocrystals featuring a cadmium-and-selenium-alloy inner core, and coated with sulfur alloy, zinc, cadmium, and proprietary organic molecular glue.
The team says that their devices have the same shape and the same basic components, regardless of what color they produce. The only factor that varies is size, but all quantum dots are shaped like pyramids.
“Today in order to create a laser display with arbitrary colors, from white to shades of pink or teal, you’d need these three separate material systems to come together in the form of three distinct lasers that in no way shape or form would have anything in common,” Arto Nurmikko explains.
“Now enter a class of materials called semiconductor quantum dots,” says the expert, who holds an appointment as a professor of engineering at Brown. He is also the senior author of a new paper detailing the discovery, which appears in a recent issue of the top journal Nature Nanotechnology.
Lexington, Massachusetts-based QD Vision managed to develop a wet chemistry process that enables its chemists to control the size of the quantum dots with extreme precision. This is why the researchers are able to produce light of specific wavelengths by just varying the size of the nanoscale pyramids.
Quantum dots featuring 4.2-nanometer cores yield red light, green light is produced by 3.2 nanometer cores, and blue light by 2.5-nanometer cores. Intermediary sizes produced intermediary colors, too.
“We have managed to show that it’s possible to create not only light, but laser light. In principle, we now have some benefits: using the same chemistry for all colors, producing lasers in a very inexpensive way, relatively speaking, and the ability to apply them to all kinds of surfaces regardless of shape,” Nurmikko says.
“That makes possible all kinds of device configurations for the future,” he adds. The new work was sponsored by the US Department of Energy, the Air Force Office for Scientific Research, and the National Science Foundation.