A research team, led by scientists at the Center for Molecular Bioengineering (B CUBE) at the Technical University of Dresden (Germany; www.tu-dresden.de), has converted mineral shells of single-celled algae into lead-halide perovskites with tunable physical properties. The new perovskites have unique nano-architectures unachievable by conventional synthetic production. The results were published in the journal Advanced Science.
“Unicellular organisms have responded over hundreds of millions of years to a wide range of environmental factors, such as temperature, pH and mechanical stress. As a result, some of them evolved to produce absolutely unique biomaterials that are exclusive to nature,” says Igor Zlotnikov, research group leader at B CUBE, who led the study. “Minerals formed by living organisms often exhibit structural and crystallographic characteristics that are far beyond the production capacities offered by current synthetic methods.”
The team focused on L. granifera, a type of algae that uses calcite to form shells. Their spherical shells have a unique crystal architecture — the crystals are aligned radially. “The current manufacturing methods of perovskites are not able to produce materials like this synthetically. We can, however, try to transform the existing natural structures into functional materials while keeping their original architecture” adds Zlotnikov.
To transform the natural mineral shells of algae into functional perovskites, the team had to substitute chemical elements in calcite. To do that, they adapted a method developed by their collaborators at the AMOLF institute (Amsterdam, the Netherlands; www.amolf.nl). During the transformation, scientists were able to produce different types of crystal architectures by altering the chemical makeup of the material. In that way, they could fine-tune their electro-optical properties. For example, by converting the calcite shells to lead halides with either iodine, bromide or chloride, the team could create functional perovskites that are optimized to emit only red, green or blue light.