Perovskites are new materials ideally suited to produce solar cells and light-emitting diodes (LEDs) thanks to their appealing optoelectronic properties. For the past ten years, the research community has tried to delve deeper into the essence of these mysterious semiconductors. But perovskites have proven to be untameable and enigmatic steeds. In a new study published in the research journal Nature Communications, a Swedish-German-Russian research team has for the first time, gained a deeper insight into charge carrier dynamics in perovskites in the presence of crystal defects. Using a new spectroscopy technique, researchers have managed to create horse-like two-dimensional diagrams that give a broad representation of the material's diverse characteristics by revealing them all in a single picture.
“Mapping a perovskite sample with this method gives us an incredible amount of new information. It's like getting a fingerprint from a semiconductor”, says Ivan Scheblykin, chemistry researcher at Lund University.
Along with his colleagues, Scheblykin was able to produce detailed 2D diagrams that map how the material's photoluminescence and decay dynamics vary with the strength of the laser pulses and the time delay between them. Using the horse-like diagrams, the research team was then able to study the rich palette of perovskite’s characteristics.
“For some reason, the 2D maps resemble the shape of horses’ necks with flying mane. It is a funny situation leading us to refer to them as perovskite horses. Now that we have learned more about their previously unknown properties, we can ride out to completely new terrain”, says Ivan Scheblykin.
The breakthrough with the new spectroscopy method – which is also applicable to other semiconductor materials – means that researchers now have a tool to quantitatively test theories previously used to try to explain the photophysical properties of perovskites.
“With more detailed knowledge of perovskites, it will be easier to modify the materials and develop new and more efficient solar cells and light-emitting diodes in the future. Something that will benefit both humans and the environment”, says Ivan Scheblykin.
The new spectroscopy technique is an indirect result of the global Covid-19 pandemic. As researchers have been unable to meet and work in their regular laboratory environment, they were forced to create a technique that is completely automated.
“As we could not work in the lab as we usually would, we had to modify our initial experimental setup. It was actually these changes that led to this major breakthrough, by a dramatic increase in precision”, says Ivan Scheblykin.
This project was essentially a collaborative effort of Lund University, the Russian Academy of Science and the Technical University of Dresden.
The study has been published in the research journal Nature Communications.
Read the study – nature.com