Multifunctional cellulose fibers: Intense red upconversion under 1532 nm excitation and temperature-sensing properties

Abstract

The unique properties of upconverting nanoparticles are responsible for their various applications in photonic materials, medicine, analytics, or energy conversion. In this work, the NaErF₄:Tm³⁺@NaYF₄ core@shell nanoparticles were synthesized by reaction in high-boiling point solvents and incorporated into cellulose fibers. Nanoparticles showed intense upconversion under 1532 nm excitation wavelength due to Er³⁺ in their structure. Additional co-doping with Tm³⁺ ions allowed to shift of the typical green luminescence of Er³⁺ ions to red especially demanded in anti-counterfeiting applications. The products' composition, morphology, and structure parameters confirmed their requested properties. The article demonstrates that cellulose fibers are suitable carriers of NaErF₄:Tm³⁺@NaYF₄ NPs. We also show that the temperature-dependent emission of Er³⁺ ions allows for the preparation of temperature-sensing cellulose fibers.

Keywords: Cellulose fibers; Erbium acetate (PubChem CID: 168385); Lanthanides; Microcrystalline (PubChem CID: 14055602); Nanoparticles; Sensors; Sodium erbium tetrafluoride (PubChem CID: 46207719) cellulose; Thulium acetate (PubChem CID: 170163); Upconversion; Yttrium acetate (PubChem CID: 168102).