Non-interfering dual-mode luminescence with persistent emission under UV excitation and upconversion thermometry under NIR excitation in Ca3Ga4O9: Pr3+, Er3+, Zn2+

Abstract

The excitation-dependent trapping/detrapping kinetics inherent to persistent luminescence (PersL) materials give rise to non‑unique thermometric spectral responses, rendering PersL and fluorescence thermometry intrinsically incompatible and thereby impeding the development of multifunctional luminescent materials. To overcome this challenge, a multifunctional phosphor, Ca3Ga4O9:Pr3+,Er3+,Zn2+, was developed based on a function-decoupling strategy enabled by distinct excitation modes, successfully integrating PersL with upconversion fluorescence thermometry. Under 254 nm UV excitation, the phosphor exhibits blue-green PersL arising from the combined emission of Pr3+ and Er3+, and Zn2+ co-doping increases the total relative trap density by approximately 13 times, resulting in a pronounced enhancement of the PersL intensity. While under 980 nm excitation, the Er3+ upconversion luminescence enables temperature sensing via the fluorescence intensity ratio (FIR) of the thermally coupled 2H11/2/4S3/2 levels, with a maximum relative sensitivity Sr of 1.64% K-1 at 253 K. The independent excitation pathways for PersL and temperature sensing avoid the signal interference under the designated operating conditions. The phosphor integrates UV excitation wavelength-dependent color tunability, PersL, and NIR-excited temperature-sensitive optical thermometry. This multifunctional feature offers a novel strategy for combining multiple optical functionalities within a single luminescent system and may provide a basis for future exploration in optical identification and temperature sensing