Multimodal deep red luminescent ratiometric thermometer of LaAlO3 doped with Mn4+

Abstract

Mn 4+ ions show red to deep-red luminescence due to the 2 E→ 4 A 2 spin-forbidden transitions in several host materials. Especially, Mn 4+ -doped LaAlO 3 with perovskite structure shows the deep red luminescence with a quite long wavelength around 730 nm in the first biological window. In this study, we investigated the temperature dependence of the photoluminescence spectra of Mn 4+ -Ca 2+ co-doped LaAlO 3 (LAP: Mn 4+ -Ca 2+ ) and a possibility as a thermometer based on the energy shift of zero-phonon-line (ZPL) and the luminescence intensity ratio (LIR) of thermally coupled ZPL and anti-Stokes phonon sideband (PSB). As a result, the LAP: Mn 4+ -Ca 2+ phosphor shows the continuous energy shift of ZPL with temperature and three different temperature dependences of the LIR by selecting different two luminescence bands, which means that the LAP: Mn 4+ -Ca 2+ phosphor has four different thermometric functions in one phosphor. All the thermometers show a good relative sensitivity and wide working temperature range from 100 K to physiological temperature.