New method brings single-particle quality control to nanocrystal manufacturing Lisa Lock Scientific Editor Andrew Zinin Chief Editor Nanocrystals are already used in millions of devices, including televisions, laptops and displays, and are considered key materials for the next generation of quantum, sensing and solar technologies. However, they have not yet fully realized their potential. One major reason is their inherent heterogeneity: A single solution contains billions of nanocrystals whose properties can differ substantially.

Although these particles can be characterized, important quality parameters are typically accessible only as average values across the entire sample. "For their function in devices, these average values are insufficient," says Professor Emiliano Cortés, who conducts research at LMU's Nano-Institute. "Each individual nanoparticle can behave differently—for example, in its size or in how efficiently it emits light, meaning how effectively it converts absorbed energy back into light." A new light-based methodology Cortés and his team show how this gap can be closed in a recent publication in the journal Nature Materials.

In the study, the researchers determined the size and quantum yield of thousands of individual perovskite nanocubes directly in solution in a short time. "We have developed a light-based high-throughput method that enables quality control at the single-particle level," explains LMU nanoscientist Dr. Christoph Gruber, first author of the study.

"This is crucial for the reliable production of materials and the devices built from them. Billions of nanoparticles determine the overall performance. Instead of relying on averaged values, we can now differentiate how strongly individual particles contribute and how much they vary within a sample." A key factor in the success of the study was the close collaboration with other LMU researchers, in particular the team led by Professor Alexander Urban.

This group specializes in the synthesis of perovskite nanocrystals and produced the nanocubes used in the study. The investigated perovskite nanocubes are smaller than 20 nanometers (0.0008 inches) and can differ significantly in their optical performance, even within seemingly uniform samples. Urban explains, "We can now look specifically at individual particles and identify clear trends: Smaller nanocrystals, for example, show a higher quantum yield—meaning they emit light more efficiently—than larger ones.

This understanding is crucial for fully exploiting the potential of perovskites for high-performance and scalable optoelectronic devices." Nanocubes under quality control Achieving high-throughput screening was technically demanding: Thousands of particles had to be measured quickly, precisely and reproducibly. "A major challenge was handling the large volumes of data and establishing a reliable analysis pipeline," says LMU nanoscientist Dr. Andrea Mancini, co-first author of the study.

In addition, perovskite nanocrystals are sensitive materials: They react to intense light exposure, oxygen or moisture and can change during measurement. "We had to ensure that we were really measuring the original material rather than a degradation product," Cortés explains.