A sand dollar skeleton gradually converting into a light emitting perovskite

The calcite shell of a sand dollar (Mellita isometra) is shown as it is transformed into an identical structure of lead–halide perovskite (green). Credit: Noorduin Lab, AMOLF

Chemistry

Glow-in-the-dark semiconductor seashells

3D models can be converted to crystalline material without losing their shape.

By swapping ions in and out, an intricate object made from a biologically inspired mineral is transformed into a semiconductor of identical shape.

Willem Noorduin and his colleagues at the AMOLF physics institute in Amsterdam began with templates composed of barium carbonate, a compound similar to calcium carbonate — the main ingredient of coral reefs and seashells. The researchers swapped the compound’s metal ions for lead ions, and then replaced the carbonate ions with halide and methylammonium ions.

This created objects that looked identical to the templates — which included shell and coral shapes — but were composed of lead–halide perovskite, a crystalline material that can be crafted into highly efficient solar cells. The perovskite structures performed just as well as state of-the-art perovskite films in absorbing and re-emitting light, suggesting that the fabrication technique could be used to make 3D devices with optical and electronic applications.