Multi-mode ratiometric thermometry using thermo-intensified NIR emission

Abstract

Luminescence ratiometric thermometry has enabled fast-responsive and non-invasive temperature detection in microelectronic devices and biological systems, but it still suffers from limited thermal sensitivity and serious thermal quenching effects. Herein, a facile hydrothermal method was developed to construct monodispersed candy-like NaY(MoO4)2:Yb3+/Nd3+ micro-thermometers that exhibit efficient near-infrared anti-stokes luminescence under 980 nm excitation. By leveraging active lattice phonon, phonon-assisted Yb3+ → Nd3+ energy transfer and excited-state absorption of Nd3+ were greatly promoted as the temperature elevated, resulting in a giant and reversible enhancement of 4F7/2, 4S3/2 → 4I11/2 transition by around 1683-folds. Luminescence intensity ratios of these near-infrared emissions featured a strong thermal response under the excitation of 980 and 808 nm, enabling the multi-mode thermometry with high sensitivity and resolution (Sr = 4.69% K−1 and δT = 0.071 K at 303 K). A flexible thermometer was further fabricated by embedding as-prepared microcrystals into the thin-film substrate, offering precise multi-mode thermal monitoring at the local hotspot in the electronic component.