Atom swapping makes brighter perovskite LEDs
Swapping one out of every thousand lead atoms for manganese tripled the luminescence of halide perovskite quantum dots
An international group of researchers has developed a new technique that could be used to make more efficient low-cost light-emitting materials which are flexible and can be printed using ink-jet techniques.
The researchers, led by the University of Cambridge and the Technical University of Munich, found that by swapping one out of every thousand lead atoms for manganese, they were able to triple the luminescence of halide perovskite quantum dots.
This doping, causes the charge carriers to get stuck in a specific part of the material's crystal structure, where they recombine and emit light. The results, reported in the Journal of the American Chemical Society, could be useful for low-cost printable and flexible LED lighting, displays for smartphones or cheap lasers.
The Cambridge researchers worked with Daniel Congreve's group at Harvard, who are experts in the fabrication of quantum dots.
A detailed investigation using laser spectroscopy revealed the origin of this observation. "We found that the charges collect together in the regions of the crystals that we doped," said Sascha Feldmann from Cambridge's Cavendish Laboratory, the study's first author. "Once localised, those energetic charges can meet each other and recombine to emit light in a very efficient manner."
"We hope this fascinating discovery: that even smallest changes to the chemical composition can greatly enhance the material properties, will pave the way to cheap and ultrabright LED displays and lasers in the near future," said senior author Felix Deschler, who is jointly affiliated at the Cavendish and the Walter Schottky Institute at the Technical University of Munich.
In the future the researchers hope to identify even more efficient dopants which will help making these advanced light technologies accessible to every part of the world.
'Charge Carrier Localization in Doped Perovskite Nanocrystals Enhances Radiative Recombination' by Sascha Feldmann et al; J. Am. Chem. Soc. 16th May 2021
