Solar cells—now in a rainbow of colors

MIGUEL ANAYA/INSTITUTE OF MATERIALS SCIENCE OF SEVILLE

Solar cells—now in a rainbow of colors

Sure, solar panels are good for the environment, but they’re so … boring. Now scientists have found a way to spice things up. In a study published online this month in Nano Letters, researchers describe making solar cells in several colors (pictured) that still perform efficiently. The scientists layered silicon dioxide, a common material to make glass optical fibers, and titanium dioxide, widely used to absorb harmful ultraviolet rays in sunscreens, alternately to create a structure called photonic crystal that can interact with light. Then they placed a layer of perovskite, the light-harvesting material, on top of the photonic crystal. The colors appear as a result of a combination of light reflected by the photonic crystal and absorbed by the perovskite; they can be changed by varying the thickness of individual silicon or titanium layers in the photonic crystal section. One downside: The colored cells are less efficient than their black counterparts, converting—at most—about 9% of the sunlight they receive into electricity, versus 25% for traditional cells. Still, the team hopes that the colorful cells could win over people averse to solar panels and boost solar adoption on buildings and other structures.