Infrared excitation induced upconversion fluorescence properties and photoelectric effect of NaYbF4:Tm3+@TiO2 core–shell nanoparticles

Abstract

NaYbF₄:Tm³⁺@TiO₂ core–shell nanoparticles were successfully synthesized by the hydrothermal method, followed by hydrolysis of tetrabutyl titanate (TBOT). The ultraviolet and blue UC luminescence are decreased significantly for NaYbF₄:Tm³⁺@TiO₂ with a 980 nm semiconductor laser, which originated from the ¹D₂ → ³H₆ and ¹D₂ → ³F₄ transitions of Tm³⁺, respectively. The inner photoelectric effect of NaYbF₄@TiO₂ core–shell structure is also found by exciting the core–shell structure under 980 nm excitation, which is attributed to excitation energy migration from the NaYbF₄:Tm³⁺ core to the TiO₂ shell. This study suggests a promising system to utilize the near-infrared energy of sunlight for photoelectrical applications based on TiO₂, which will be the efficient infrared photoelectric materials in future.