Upconversion Emission from Yb³⁺ and Tm³⁺ Codoped NaYF₄ Thin Film Prepared by Thermal Evaporation

Abstract

Yb3+ and Tm3+ codoped fluoride thin film, with intense ultraviolet and visible upconversion emissions under 980 nm excitation, has been deposited on an Al2O3 ceramic substrate by thermal evaporation under high vacuum. NaY(0.835)Yb(0.15)Tm(0.015)F4 bulk material synthesized by high temperature solid-state reaction was used as target in preparing the thin film. Yb3+ and Tm3+ codoped system, which had been reported before, had been studied. Compared with the unannealed thin film, the annealed film showed better upconversion emission properties, especially in the ultraviolet region, given in the normalized upconversion emission spectra, due to the structure changed from amorphous to hexagonal NaYF4 (beta-NaYF4) during the annealing process. The upconversion mechanism of the thin film was also discussed in this paper.

A Room-Temperature Strategy to Synthesize Ce/Tb-Codoped NaYF4 Nanoparticles with a Photoluminescence Quantum Yield Exceeding 50%

“…NaYF 4 :RE 3+ nanomaterials, the important members of the fluoride system, have received extensive attention in recent years. − Various methods have been developed to synthesize NaYF 4 :RE 3+ nanomaterials, including hydrothermal/solvothermal methods, − facile molten salt method, , precipitation methods, , thermal decomposition methods, , and refluxing methods. − However, while these solution methods offer the advantage of low-temperature synthesis compared to the high-temperature solid-state method, , they often result in NaYF 4 :RE 3+ nanocrystals with abundant surface defects, poor crystallinity, and low luminescence performance. This is particularly problematic as there is a growing demand for ultrasmall nanophosphors with particle sizes less than 10 nm, due to light scattering effects and the requirement for bioimaging application.…”

Chelating agent and substrate effect on hydrothermal growth of Yb3+/Er3+ doped NaYf4 film

“…Several processing methods for growing rare-earth doped upconverting platforms have been reported using thin-film deposition techniques, such as layer by layer deposition (LBL) [15], dip-coating [16], pulsed laser deposition (PLD) [17][18][19], spin coating [20], thermal evaporation [21] electron-beam vaporization [14], etc. However, these technologies start with an already synthesized upconverting base material, which are subsequently processed to make films.…”

Heterobimetallic Sodium Rare-Earth Complexes: “Third-Generation” MOCVD Precursors for the Deposition of NaREF4 (RE = Y, Gd) Films

“…However, photonic applications require the UC materials to be in thin-film form, but so far the fabrication of NaYF 4 and NaGdF 4 materials in thin-film form has been scarcely investigated. In particular, electrodeposition, thermal evaporation, and sol–gel/spin-coating approaches have been applied to synthesize UC NaYF 4 and/or NaGdF 4 films.…”