This is an optical microscopic image of a pattern formed from a polymer thin film in response to an electric field. The dots in the image are top views of pillars growing from a polymer film. When voltage is applied onto two parallel electrodes with a layer of polymer film and a gap in between, the voltage drives the polymer pillar to grow into the gap. These pillars have different diameters and separations due to a range of experimental conditions. These conditions include material properties such as the sensitivity to the applied voltage as well as geometric properties such as the thicknesses of the layers and the strength of the driving force.

These pillar patterns have the potential of selectively allowing the passage of light with different energies -- hence the potential to act like an “energy selector.” On the other hand, when this patterning technique is applied on a wavelength converting material, the resulting product can act as a concentrator for electromagnetic energy.