With her hands cloaked in aquamarine rubber gloves, Vivian Ferry, an assistant professor of chemical engineering and materials science, picks up a lipstick-size test tube filled with clear liquid. When she shines UV light through the tube, its contents turn a glowing shade of fluorescent orange. Tiny crystals suspended in the liquid explain the vial’s fiery glow: they absorb high-energy blue wavelengths and emit lower-energy reds.

Existing solar cells tend to absorb limited wavelengths of light, letting most of the sun’s energy pass through uncaptured. If solar cells could grab more light, they would generate more electricity and make solar power even cheaper. So in addition to the luminescent crystals, Ferry turned to tiny mirrors made of nanostructured metals that can trap specific wavelengths and steer light toward the solar cell.

For now, Ferry makes her luminescent nanocrystals with cadmium selenide and cadmium sulfide, neither of which is ideal since cadmium is a toxic metal. But her improvements—and subsequent drops in cost—stand to become so significant that the technology could still work well using substances that are more abundant and less toxic.

—Emily Sohn