Orthogonal optical encoding via excitation-modulated core–shell perovskite nanocrystals

Abstract

Lanthanide-doped nanocrystals capable of color-tunable upconversion luminescence have attracted significant attention. However, current research primarily focuses on complex multi-layered core–shell architectures, making the structural design simplification for achieving tunable upconversion emission a persistent challenge. Here, leveraging the superior optical properties of double perovskites, we propose a simplified core–shell model (Cs₂NaYF₆:Er³⁺@Cs₂NaYF₆) to achieve orthogonal upconversion luminescence of Er³⁺ under different excitation wavelengths. Red-green switchable upconversion luminescence can be realized under dual-channel selective NIR wavelength (980 nm and 1550 nm) excitation, which is attributed to the distinct cross-relaxation rates of Er³⁺ under different excitation modes. Moreover, the coating of an inert shell further enhances the emission intensity (∼220-fold) by suppressing energy migration to surface quenching centers. This excitation-wavelength-gated upconversion luminescence modulation is successfully applied in information encoding and decoding based on the optical logic gate. These findings provide valuable insights for simplifying the design of tunable upconversion in core–shell nanostructures, offering significant potential for advanced information security applications.