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 (SR). To circumvent these limitations, we propose an intervalence charge transfer mashup strategy by inducing d0 electron configured transition metals. Specifically, transition metals Ta5+ is incorporated in Tm3+/Eu3+:LiNbO3, which improves the SR from 5.30 to 11.16% K-1. The validity of this component-modulation behavior is observed on other oxide crystals (NaY(Mo1-zWzO4)2) 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 SR to the band structure of luminescence carrier, offering a novel perspective for the collocation design of lanthanide configurations.