A generalized approach to photon avalanche upconversion in luminescent nanocrystals

TL;DR

This paper introduces a generalized method using Gd3+ to extend photon avalanche upconversion in nanocrystals, enabling highly nonlinear emission across a broader spectrum for advanced imaging and sensing.

Contribution

It presents a novel Gd3+-assisted energy migration strategy to tune emission wavelengths and induce avalanche behavior in various lanthanide-doped nanocrystals and fluorophores.

Findings

Achieved nonlinear upconversion with Eu3+, Tb3+, Ho3+, and Er3+ ions.

Demonstrated low-power excitation at 1064 nm for high nonlinearity.

Extended avalanche behavior to quantum dots for biological applications.

Abstract

Photon avalanching nanoparticles (ANPs) exhibit extremely nonlinear upconverted emission valuable for sub-diffraction imaging, nanoscale sensing, and optical computing. Avalanching has been demonstrated with Tm3+, Nd3+ or Pr3+-doped nanocrystals, but their emission is limited to 600 and 800 nm, restricting applications. Here, we utilize Gd3+-assisted energy migration to tune the emission wavelengths of Tm3+-sensitized ANPs and generate highly nonlinear emission of Eu3+, Tb3+, Ho3+, and Er3+ ions. The upconversion intensities of these spectrally discrete ANPs scale with the nonlinearity factor s = 10-17 under 1064 nm excitation at power densities as low as 6 kW/cm2. This strategy for imprinting avalanche behavior on remote emitters can be extended to fluorophores adjacent to ANPs, as we demonstrate with CdS/CdSe/CdS core/shell/shell quantum dots. ANPs with rationally designed energy transfer networks provide the means to transform conventional linear emitters into a highly nonlinear ones, expanding the use of photon avalanching in biological, chemical, and photonic applications.