Dynamic manipulation of upconversion luminescence by constructing metal–organic framework and lanthanide-doped nanoparticle composites†

The dynamic manipulation of multi-photon upconversion, enabling rich and tunable emission colors, has generated significant interest in lanthanide-doped upconversion nanoparticles (UCNPs) about their fundamental research and frontier applications. However, manipulating photochromic upconversion emissions towards luminescent color tuning (LCT) of a single UCNP emitter without tedious endogenous regulation remains a challenging endeavor. In this study, NaYF₄@NaYF₄:x%Yb, 2%Er (X = 60, 80 and 98) was incorporated with UiO-66-type metal–organic frameworks (MOFs, including UiO-66, UiO-66-NDC, UiO-66-NH₂) by a simple and versatile in situ synthesis method. The UCNPs are combined with MOFs in a monodisperse state, and the stability of the composites is improved compared to UCNPs alone. Effective modulation of the upconversion luminescence (UCL) properties of UCNPs was achieved by exploiting the chemical bonds with high-energy vibrations in MOFs, which facilitates the multi-phonon relaxation (MPR) processes of Er³⁺. Our findings enable versatile designs and dynamic control of emission colors from luminescent materials, opening up new opportunities for their advanced photonic applications, notably in optical anti-counterfeiting.