A Generalized Approach to Photon Avalanche Upconversion in Luminescent Nanocrystals

Photonavalanching nanoparticles (ANPs) exhibit extremelynonlinearupconverted emission valuable for subdiffraction imaging, nanoscalesensing, and optical computing. Avalanching has been demonstratedwith Tm3+-, Pr3+-, or Nd3+-dopednanocrystals, but their emission is limited to a few wavelengths andmaterials. Here, we utilize Gd3+-assisted energy migrationto tune the emission wavelengths of Tm3+-sensitized ANPsand generate highly nonlinear emission from Eu3+, Tb3+, Ho3+, and Er3+ ions. The upconversionintensities of these spectrally discrete ANPs scale with nonlinearityfactor s = 10-17 under 1064 nm excitationat power densities as low as 7 kW cm(-2). This strategyfor imprinting avalanche behavior on remote emitters can be extendedto fluorophores adjacent to ANPs, as we demonstrate with CdS/CdSe/CdScore/shell/shell quantum dots. ANPs with rationally designed energytransfer networks provide the means to transform conventional linearemitters into a highly nonlinear ones, expanding the use of photonavalanching in biological, chemical, and photonic applications.

Automated summary

Photonavalanching nanoparticles (ANPs) with highly nonlinear upconverted emission have great potential for subdiffraction imaging, nanoscale sensing, and optical computing. We use Gd3+-assisted energy migration to tune the emission wavelengths of Tm3+-sensitized ANPs and generate highly nonlinear emission from Eu3+, Tb3+, Ho3+, and Er3+ ions. The upconversion intensities of these spectrally discrete ANPs scale with a nonlinearity factor s = 10-17 under 1064 nm excitation at power densities as low as 7 kW cm(-2). This strategy can be extended to fluorophores adjacent to ANPs, as shown with CdS/CdSe/CdS core/shell/shell quantum dots.