Rebekka Klausen's doctoral research focused on carbon-carbon bonds. This is common in her discipline. Carbon-carbon bonds—that is, carbon atoms bonding through shared electrons to form a multitude of molecules—are structures so fundamental to life they get their own field of scientific inquiry: organic chemistry. But as a postdoc, Klausen noted that silicon sits just below carbon in its column of the periodic table. An important aspect of that table is that elements in the same column have similar sorts of bonding and reactivity. "I became really interested in exploring that," she says. "Here is this element, silicon, that is so important in the electronics industry, but its synthetic chemistry is so much less understood than carbon's. Could I bring my skills as someone who knows how to make carbon-carbon bonds to understanding the chemistry of silicon-silicon bonds?"
Good career move, as it turns out. Klausen, an assistant professor of chemistry in the Krieger School, recently learned she is one of the 44 young scientists who have been awarded substantial grants by the U.S. Department of Energy as part of its Early Career Research Program. She will receive $750,000 over the next five years to work on the chemistry of silicon.
Silicon is abundant, mainly in the form of silica, a compound of silicon and oxygen that makes up 90 percent of the Earth's crust. And it's important: semiconductors, solar cells, and all kinds of tech depend on it. But abundant plus important does not automatically mean well understood. Klausen plans to use the DOE funding to study the chemistry of silicon at the nanoscale, including development of chemical reactions that precisely control the dimensions of silicon nanomaterials and their size-dependent properties. Figure that out, Klausen hopes, and she'll be able to better control silicon's electronic and light-absorbing properties, which will have powerful implications for applications like light-emitting diodes and solar cells. She is convinced the future of silicon technology will be integrating nanoscale silicon into mesoscale materials.
Klausen is a synthetic chemist, and she has a succinct explanation of the distinction: "Chemists can be divided into make, model, and measure. Theoretical chemists model a structure or phenomenon. Then there are chemists who measure, like a physical chemist or analytical chemist. Synthetic chemists make things. I'm a maker." As a maker, she is most interested in how a material's structure determines its function. She says, "What I want to do is be able to say, 'Here's a function we want from a silicon material, and this is a structure that will achieve it.'" One source of inspiration for her is the diatom, one of the few silica-based life forms on Earth. Diatoms have remarkable and beautiful symmetrical structures, executed at a tiny, tiny scale. "As someone who builds things," Klausen says, "I'd love to have that amount of precision."