Wednesday, July 6, 2022

Making more efficient low-cost light-emitting materials by swapping atoms

Atom swapping could lead to ultra-bright, flexible next-generation LEDs.

LEDs are being used in many applications such as domestic and commercial lighting, TV screens, smartphones, and laptops. As compared to conventional technologies, LEDs consume far less energy.

Scientists at the University of Cambridge and the Technical University of Munich have studied a new class of semiconductors called halide perovskites in the form of nanocrystals. These ‘quantum dots’ are highly luminescent materials.

Recently, scientists were able to improve the light emission from these nanocrystals. They did this by using a new technique: swapping one out of every one thousand atoms of one material for another.

Doing so triple the luminescence of halide perovskites.

In atom swapping, charge carriers get stuck in a specific part of the material’s crystal structure, where they recombine and emit light.

Sascha Feldmann from Cambridge’s Cavendish Laboratory, the study’s first author, said, “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. Once localized, those energetic charges can meet each other and recombine to emit light in a very efficient manner.”

Senior author Felix Deschler, who is jointly affiliated at the Cavendish and the Walter Schottky Institute at the Technical University of Munich, said“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.”

This work could have significant implications in low-cost printable and flexible LED lighting, displays for smartphones, or cheap lasers.

Journal Reference:
  1. Sascha Feldmann et al. Charge Carrier Localization in Doped Perovskite Nanocrystals Enhances Radiative Recombination. DOI: 10.1021/jacs.1c01567

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