Structural Confinement Induced Near-Unity Quantum Yield for Single-Band Ratiometric Thermometry

Abstract

Luminescence quenching at high dopant concentration and temperature typically limits the brightness of luminescence materials, which remains a major obstacle in diverse technological applications, especially in the field of luminescence thermometry. In this work, a unique class of non-concentration quenching double-tungstate phosphors is reported that feature the near-unity quantum yield of Tb3+ and Eu3+ emissions induced by the structural confinement effect. Mechanistic studies affirm that the activator ions can be isolated in NaYW2O8 crystal to confine the absorbed photon energy, leading to a relatively high quenching concentration of various lanthanide activators. By facilitating interionic cross-relaxation at heavy dopant concentration, a remarkable thermal enhancement of Tb3+ emissions over 20-fold upon the excitation of excited-state absorption is recorded. In contrast, thermally quenched emissions are detected under the excitation of ground-state absorption. This excitation wavelength-dependent thermal behavior of Tb3+ emissions is harnessed for single-band ratiometric thermometry, registering superior thermal sensitivity and resolution (Sr = 4.01% K−1, δT = 0.1 K). The advances in combating concentration and thermal quenching of luminescence materials provide exciting opportunities for flexible thermometry in real-world sensing scenarios.