A photonic crystal is a nanostructure with a regular pattern that influences the motion of photons. By changing the structure slightly, we can change the color of light that the crystal reflects. The color changes according to our desire can be controlled by varying applied voltage. The technology could enable brighter, flexible color displays for electronic readers and billboards.The amazing thing of this novel technology of the photonic crystal is that each pixel can be tuned to emit different colors. Hence, it can be used to obtain good brightness more similar to printed paper. The current technology used in e-paper, uses reflection of light instead of emitting light.
The researchers made photonic crystals using stacks of hundreds of silica nanospheres embedded in a polymer. They sandwiched these stacks along with an electrolyte--a material that conducts ions--between two transparent electrodes coated on glass. When different voltages are applied, the electrolyte goes in and out of the polymer, which swells and shrinks, altering the distance between the nanospheres. This changes the wavelength of the reflected light.
According to researchers, this technology can replace some of the conventional display technology.