Researchers at the Department of Energy’s Oak Ridge National Laboratory got a surprise when they built a highly ordered lattice by layering thin films containing lanthanum, strontium, oxygen and iron. Although each layer had an intrinsically nonpolar (symmetric) distribution of electrical charges, the lattice had an asymmetric distribution of charges. The charge asymmetry creates an extra “switch” that brings new functionalities to materials when “flipped” by external stimuli such as electric fields or mechanical strain. This makes polar materials useful for devices such as sensors and actuators.
Photovoltaic spray paint could coat the windows and walls of the future if scientists are successful in developing low-cost, flexible solar cells based on organic polymers. Scientists at the Department of Energy’s Oak Ridge National Laboratory recently discovered an unanticipated factor in the performance of polymer-based solar devices that gives new insight on how these materials form and function.