Solar energy research heats up

Dr. Edward Remsen, below, is on a mission to ensure solar energy is a viable heat source in the years ahead.

The Bradley University chemistry professor and other scientists worldwide are conducting research to find a way to increase the energy efficiency of dye-sensitized solar cells. “The European Union’s goal is to be using renewable energy sources 20 percent of the time by 2020,” Dr. Remsen says. “Dye-sensitized solar cells are part of the mix. 

“This is very much an international issue. We’re not just interested in how much energy production we have now, but also the growth in energy production. As the economy grows, we’ll be depending on renewable energy sources even more.” 

Dye-sensitized solar cells are a cheaper alternative to silicon solar cells, the standard in today’s solar energy applications. However, the conversion efficiency of dye-sensitized solar cells is only about 10 percent, about half as efficient as commercial, single-crystal silicon cells.

“If the efficiency goes up and the cost is still low, then dye-sensitized cells can compete with the silicon solar cell technology,” Dr. Remsen says. 

He believes that under-standing the process of how these cells work at a molecular level will help all researchers as they work toward increasing the cells’ efficiency. “If we understand the basics, maybe we can break this 10 percent energy efficiency barrier.”

Dye-sensitized solar cells use a thin film composed of titanium dioxide, an inexpensive semi-conducting material. Light-absorbing dye is incorporated into the film. When light enters the cell, it is absorbed by the dye, which promotes electrons in the dye into a higher energy state. The energized electrons diffuse into the titanium dioxide film, which creates a current and generates electricity.

Dr. Remsen’s research involves the study of a key process regulating the solar energy conversion efficiency — the transport of charged molecules through the semi-conducting titanium dioxide film.

His goal is to add his findings to the collective worldwide research under way so dye-sensitized solar cells can become commercially viable devices. The demand for renewable energy resources is increasing as people realize the reserve of fossil fuels is limited. Last summer’s oil leak in the Gulf of Mexico emphasized the need to find viable renewable energy sources.

“The sun is there every day, and its total output is enormous,” Dr. Remsen says. “One hour of solar output falling on the Earth is equivalent to the amount of energy used by humans in one year. We don’t have to capture it all. It all boils down to economics. How much are people willing to pay for renewable energy?”

While it’s natural to look for “the” answer to the world’s energy needs, Dr. Remsen says the ultimate solution will be a mix of geothermal, wind, and solar energy sources. He sees himself as an integral part of a worldwide network of scientists trying to find economical renewable energy sources.

“We have real solutions here. We don’t have to keep fouling the planet. It will be the result of many people’s research to get to a better place than we are now,” he says.