Cottrell Scholar Awards - 2015
Development of Polymers for Next-Generation Singlet Fission Solar Cells
Worldwide energy consumption is at an all-time high. Meanwhile, the International Energy Agency reports that only about one percent of our power comes from electricity generated from alternative sources (hydro, solar and wind). It would appear humanity’s addiction to fossil fuels shows no significant sign of easing.
Luis M. Campos, assistant professor of chemistry at Columbia University, has received Cottrell Scholar funding to attempt to correct this situation.
Campos and his associates are working to develop highly efficient third-generation solar cells that produce electricity directly from sunlight. This third generation requires developing materials for solar panels that generate multiple excited electrons (technically called “excitons”) from one incoming photon, the smallest particle of light.
“Commercially, renewable energy from solar cells has been dominated by first-generation technology based on silicon wafers. These photovoltaic devices are expensive to make,” Campos said.
He noted that second-generation solar cells have begun to appear on homes and businesses. These rely on so-called “thin-film” technology with significantly cheaper manufacturing costs. They are based on materials like carbon-based plastics, as well as cadmium telluride and perovskites. Unfortunately these devices, like first-generation silicon panels, generate only one exciton per photon.
These first- and second-generation solar cells bump up against the Shockley-Queisser limit, which defines the upper theoretical value of power conversion efficiency at 33% due to heat losses within the solar cell.
On the other hand, Campos points out, third-generation solar cells have the potential to be significantly more efficient, at 44%. One of the keys to benefitting from this potential increased efficiency, he believes, is to develop third-generation cells made from cheap, abundant raw materials.
Thus he and his associates are designing new organic (carbon-based) molecules that allow one incoming photon to produce multiple excitons. The useful molecules they are creating are generally known as “polymers,” which is a chemistry term that indicates they are made from chains of smaller molecules called monomers. Many things, from the plastic in a grocery bag to the DNA in our cells, are composed of polymers.
“Developing materials for next-generation solar cells has the potential to revolutionize the renewable energy landscape, reducing the cost of power generation with highly efficient devices,” Campos said.
Campos is also using some of his Cottrell Scholar funding to institute modern “active learning” techniques within Columbia’s Organic, Materials and General Chemistry courses. As opposed to the traditional classroom lecture, active learning involves a collaborative approach in the classroom as students work to understand and solve problems. Campos said he is also developing additional techniques to minimize rote learning and the traditional lecture as a means of imparting scientific knowledge.