Sharpening upconversion nanoparticles to reduce surface quenching.

Lanthanide-doped upconversion nanocrystals with different surface sharpness properties were synthesized to study the effects of surface sharpness on optical performance. Nanocrystals with hexagonal sharp surfaces showed a significant reduction in the number of surface defects and increased the luminescence intensity by 2.5 times compared to nanocrystals with spherical surfaces.