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Dazzling, Energy-efficient Color Displays

Electronic displays, found in cell phones, laptops and tablets, are rapidly expanding into other applications. However, displays based on conventional liquid crystal display technology are energy hungry because they emit their own light. Suspension-based electrophoretic inks, which have become popular in electronic book readers, reflect light from their surroundings, making them more energy efficient. The challenge: these inks only produce black and white displays. 

To overcome this limitation, researchers at Yale University and the University of Delaware (UD) have demonstrated an energy-efficient concept for electronic inks. They created uniform, dumbbell-shaped polymer particles, 10 times smaller than previously achieved. When an electric field is applied, the particles exhibit new behavior because of their shape and size:  The particles contained in a suspension self-assemble into a crystalline structure, which changes color from white to vivid orange. When the electric field is removed, the crystalline structure rapidly disappears, and the color reverts to white. 

Because their properties can be changed with electronics, such suspensions show promise for use in color displays. This research lays the groundwork for a new generation of energy-efficient color displays for a variety of consumer and industrial applications.

This breakthrough was achieved by combining NSF-supported research at Yale and UD.  The Yale team developed an efficient and reliable method for making large quantities of identical nanoscale particles shaped like dumbells--a shape that allows them to readily align with an electric field. This work could enable scalable nanomanufacturing processes across a wide range of technologies. 

The Delaware team determined how to direct the self-assembly of nanoparticles into a crystalline structure using an electric field. With this approach the researchers control the behavior of light (or photons) on the material.

By exploiting the properties of the nanoscale dumbbell particles, this work creates dynamic photonic crystals. Previous work on self-assembled photonic materials was limited to static assemblies of spheres. 

Images (1 of )

  • colors produced when an electric field is applied to dumbbell-shaped nanoparticles
  • a close-up of the organized dumbbell nanoparticles
An electric field applied to the dumbbell nanoparticles produces these colors.
Eric Dufresne, Yale University and Eric Furst, University of Delaware
Organized dumbbell nanoparticles.
Eric Dufresne, Yale University and Eric Furst, University of Delaware

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