Highly-sensitive optical thermometer developed based on an intervalence charge transfer mashup.

Optical thermometers based on lanthanide thermal-coupled levels have attracted great attention owing to its fundamental importance in the fields of public health, biology, and integrated circuit. However, the inherent structural properties (shielded effect on 4f configurations, intense non-radiation relaxation) strictly suppress the sensing performance, limiting the relative temperature sensitivity (S). To circumvent these limitations, we propose an intervalence charge transfer mashup strategy by inducing d electron configured transition metals. Specifically, transition metals Ta is incorporated in Tm/Eu:LiNbO, which improves the S from 5.30 to 11.16% K. The validity of this component-modulation behavior is observed on other oxide crystals (NaY(MoWO)) as well. Furthermore, the observed regulation is well explained by DFT calculation that indicates the d-orbit component at valence band minimum remains the core factor governing the electron transfer process. We successfully relate the S to the band structure of luminescence carrier, offering a novel perspective for the collocation design of lanthanide configurations.