Twisting, Flexible Crystals Key to Solar Energy Production

Researchers at Duke University have revealed long-hidden molecular dynamics that provide desirable properties for solar energy and heat energy applications to an exciting class of materials called halide perovskites.

A key contributor to how these materials create and transport electricity literally hinges on the way their atomic lattice twists and turns in a hinge-like fashion. The results will help materials scientists in their quest to tailor the chemical recipes of these materials for a wide range of applications in an environmentally friendly way.

The results appeared online March 15 in the journal Nature Materials.

“There is a broad interest in halide perovskites for energy applications like photovoltaics, thermoelectrics, optoelectronic radiation detection and emission—the entire field is incredibly active,” said Olivier Delaire, associate professor of mechanical engineering and materials science at Duke. “While we understand that the softness of these materials is important to their electronic properties, nobody really knew how the atomic motions we’ve uncovered underpin these features.”

Perovskites are a class of materials that—with the right combination of elements—are grown into a crystalline structure that makes them particularly well-suited for energy applications. Their ability to absorb light and transfer its energy efficiently makes them a common target for researchers developing new types of solar cells, for example. They’re also soft, sort of like how solid gold can be easily dented, which gives them the ability to tolerate defects and avoid cracking when made into a thin film.

One size, however, does not fit all, as there is a wide range of potential recipes that can form a perovskite. Many of the simplest and most studied recipes include a halogen—such as chlorine, fluorine or bromine—giving them the name halide perovskites. In the crystalline structure of perovskites, these halides are the joints that tether adjoining octahedral crystal motifs together.

Read more about the science behind halide perovskites here >>