Researchers at the University of Delaware have received a $1 million grant from the W.M. Keck Foundation to develop new nanostructures that act like a ratchet, combining the energy of two red photons of light into a single, higher-energy blue photon. The light-changing technology could improve solar cell efficiency to chemotherapy treatments.
A traditional solar cell can only absorb light with energy above a certain threshold. If that low-energy light, however, could be transformed into higher-energy light, a solar cell could absorb much more of the sun’s energy. The team predicts that their approach could increase the efficiency of commercial solar cells by 25 to 30 percent.
The "ratchet" absorbs two red photons, one after the other, to push an electron into an excited state when it can emit a single high-energy (blue) photon. The resulting nanostructures can only be viewed when magnified a million times under a high-powered electron microscope.
The University of Delaware team will develop new semiconductor structures containing multiple layers of different materials, such as aluminum arsenide and gallium bismuth arsenide, each only a few nanometers thick. The “tailored landscape” will control the flow of electrons into states with varying potential energy, turning once-wasted photons into useful energy.
The UD engineers aim to develop an upconversion nanoparticle that can be triggered by light to release its payload, including a drug deep within diseased human tissue.
