A team of researchers from Northwestern University have developed a new set of design principles for creating photonic crystals similar to the ones that are usually used in television, computer, and smartphone displays.
DNA is unquestionably the core of life. Soon it might also be the foundation of one’s electronic systems. By employing synthetic DNA to assemble particles into crystalline lattices, the scientists have paved the way for much lighter and thinner displays compared to what is presently available.
Most people look at a laptop display every day, but few people understand what they are made of and why. One component of the display is the back-reflector, a mirror-like device that directs the light emitted by the LCD to the viewer. These reflectors are made using layered polymers that are much thicker and heavier than our crystals.”
Northwestern’s method not only substitutes these polymers with gold nanocrystals but also spaces them at a distance to leave air between them. The outcome is a lighter, more compact, precisely designed and reconfigurable structure that continues to be still very reflective.
The study was published on June 25th in the Proceedings of the National Academy of Sciences (PNAS). Schatz and Chad Mirkin, the director of Northwestern’s International Institute for Nanotechnology and the George B. Rathmann Professor of Chemistry, served as the co-corresponding authors of the paper.
In 1996, Mirkin invented ways to connect synthetic DNA to gold nanoparticles to form new materials that did not exist in nature, to fundamentally use the “blueprint of life” to program their creation. These structures have become the origin for over 1,800 globally used products, predominantly in the life sciences.
Then, in 2008, Mirkin and Schatz partnered to create crystals from particles connected by DNA. By fastening strands of synthetic DNA to miniature gold spheres, the duo found they could construct 3D crystalline structures.
Varying the DNA strand’s sequence of Gs, As, Ts, and Cs alters the shape of the crystalline structure, enabling the scientists to position the particles differently in space.
Over 500 crystal types, spanning over 30 different crystal symmetries have been made using this method, making it a robust and basically new way to program the creation of crystalline matter.
In spite of making revolutionary progress with this research since 2008, Mirkin and Schatz did not at first realize that the crystal lattices they created in the laboratory possessed optical properties akin to the polymer layers found in gadget displays.
Through computer modeling, we realized by accident that the crystalline materials with gold nanoparticles had properties that we missed earlier in the work.
We then optimized the optical properties using computations, and these demonstrated that the non-touching metal spheres could, in some cases, be better than the touching polymer spheres.”
After forming the crystals in the laboratory, Mirkin’s and Schatz’s teams measured the crystals’ optical properties to learn that their computational modeling was actually correct.
Although they only analyzed the crystalline lattice’s reflective nature in the recent PNAS paper, the technique could result in numerous types of functional “designer” materials using DNA-driven self-assembly.