Highly sensitive response of luminescence chromaticity to laser power in Lu2Mo4O15:Yb3+/Ho3+ upconverting materials

Abstract

Power-based upconversion luminescence color regulation (PUCR) is especially suitable for developing dynamic luminescence anti-counterfeiting owing to its straightforward usage. However, it remains a challenge to achieve visually remarkable Ho³⁺-based PUCR. Herein, favorable PUCR behavior is achieved by codoping Yb³⁺ and Ho³⁺ into the Lu₂Mo₄O₁₅ lattice. It has been demonstrated that the ultrashort lifetime of the Ho³⁺:⁵I₆ level and the anomalous three-photon nature of green emission are essential. The former causes high-purity red emission at low power, while the latter enables power-responsive tuning from red to green. Compared with Er₂Mo₄O₁₅:4% Tm³⁺ we recently reported that Lu₂Mo₄O₁₅:90% Yb³⁺/1% Ho³⁺, thanks to the high solubility of Yb³⁺ ions, showed a ∼25-fold enhancement in emission intensity. This new material is potentially applicable in dynamic luminescence anti-counterfeiting.