Photofunctional nanocomposites based on the functionalization of metal–organic frameworks by up/down conversion luminescent nanophosphors

Abstract

A novel strategy is demonstrated to construct photofunctional nanocomposites by composing surfactant-capped nanophosphors (upconversion NaYF₄:Yb³⁺,Er³⁺/Tm³⁺ and downconversion LaPO₄:Ln³⁺ (Ln = Ce, Eu, Tb) nanoparticles) and a zeolitic imidazolate framework (ZIF-8) unit. These nanocomposites show tunable luminescence performance for different photoactive units or different excitation wavelengths. For NaYF₄:Yb³⁺,Er³⁺/Tm³⁺@ZIF-8 nanocomposites, they display the luminescence of NaYF₄:Yb³⁺,Er³⁺/Tm³⁺ under near-infrared (NIR) 980 nm laser excitation and ZIF-8 under near-ultraviolet (NUV) 396 nm excitation. For LaPO₄:Ln³⁺ (Ln = Ce, Eu, Tb)@ZIF-8 nanocomposites, they exhibit emissions of both LaPO₄:Ln³⁺ (Ln = Ce, Eu, Tb) and ZIF-8, tuning the different luminescent colors, which indicate that there does not exist energy coupling between the two emissive centers. These results provide useful data for potential applications in optical devices.