The technology behind solar cells hasn’t changed much in decades, but efficiencies have been boosted over the years with small, incremental improvements. Even with small increases, solar cells convert less than 30% of the energy in sunlight into electricity. About half of the lost energy is due to heat generation within the silicon cell. Researchers at the University of Texas (UT) in Austin, are working on a new coating, which they hope will boost the efficiency of silicon-based solar cells by as much as 20%.
“The goal of our project is to claw back some of this energy loss by chemically attaching organic dyes to the surface of the silicon cell that reduce heat losses and convert more of that energy into electricity,” said Sean Roberts, the project’s principal investigator and an assistant professor of chemistry at UT Austin. Joining Roberts are Michael Rose, assistant professor of chemistry at UT Austin, and Joel Eaves, associate professor of chemistry at the University of Colorado Boulder.
When silicon absorbs a photon, it uses its energy to excite an electron, however much of that electron’s energy is lost as heat, so the efficiency is still relatively low. The UT team is developing dye molecules that are unique because they use the energy of a photon to excite pairs of electrons instead of just one. This allows more of the photon’s energy to be converted into electricity, and improves efficiency.
The idea of using dyes is not new, but the real technical challenge is getting the pairs of excited electrons to flow into the silicon cell so that they can be collected as current.
“Our solution is to use some synthetic approaches developed in Mike Rose’s lab to chemically tether the dyes to the silicon surface, essentially building small wires that can allow electrons to flow between the materials,” Roberts said.
The research is supported by a $1 million grant from the W.M. Keck Foundation Science and Engineering Research Grant Program and UT Austin’s Office of the Vice President for Research and College of Natural Sciences, which is providing matching funds totaling $278,500.