Versatile Spectral and Lifetime Multiplexing Nanoplatform with Excitation Orthogonalized Upconversion Luminescence

Optical encoding together with color multiplexing benefits on-site detection, and enriching the components with narrow emissions from lanthanide could greatly increase the coding density. Here, we show a typical example to combine emission color and lifetime that are simultaneously integrated in a single lanthanide nanoparticle. With the multicompartment core/shell structure, the nanoparticles can activate different emitting pathways under varied excitation. This enables the nanoparticles to generate versatile excitation orthogonalized upconversion luminescence in both emission colors and lifetimes. As a typical example, green emission of Er³⁺ and blue emission of Tm³⁺ can be triggered with 808 and 980 nm lasers, respectively. Moreover, with incorporation of Tb³⁺, not only is emission from Tb³⁺ introduced but also the lifetime difference of 0.13 ms (Er³⁺) and 3.6 ms (Tb³⁺) is yielded for the green emission, respectively. Multiplexed fingerprint imaging and time-gated luminescence imaging were achieved in wavelength and lifetime dimensions. The spectral and lifetime encoding ability from lanthanide luminescence greatly broadens the scope of luminescent materials for optical multiplexing studies.