Eu3+-Activated Single-Band Ratiometric Nanothermometry by Lattice Negative Thermal Expansion

Single-band ratiometric (SBR) thermometry has recently emerged as a powerful alternative to its dual-emission counterparts because it can avoid the large uncertainties related to the emission spectral overlap or light absorption/scattering by the medium. Herein, a novel SBR thermometric scheme in Sc2Mo3O12:Eu3+ nanosheet that depends on thermal enhancement of charge-transfer state absorption between O2- and Eu3+ is reported. Mechanistic investigation reveals the vital role of the lattice negative thermal expansion (NTE) for thermally enhanced Eu3+ emissions according to the configuration coordinate model. In contrast, serious thermal quenching of Eu3+ emissions is detected under the excitation wavelength corresponding to ground state absorption. Such excitation wavelength-dependent thermal behavior of luminescence enabled SBR thermometry with high sensitivity and resolution (S-r = 2.0% K-1, delta T = 0.121 K at 363 K). Finally, the applicability of the proposed SBR model to real-world sensing scenarios is demonstrated using the as-fabricated flexible thin-film, offering accurate and real-time temperature detection at the local hotspot in the electronic component.

Automated summary

This study reports a novel single-band ratiometric (SBR) thermometric scheme in Sc2Mo3O12:Eu3+ nanosheet based on the thermal enhancement of charge-transfer state absorption between O2- and Eu3+. Mechanistic investigation reveals the crucial role of lattice negative thermal expansion (NTE) in thermally enhanced Eu3+ emissions. In contrast, severe thermal quenching of Eu3+ emissions is observed under excitation wavelength corresponding to ground state absorption. The wavelength-dependent thermal behavior enables high sensitivity and resolution for SBR thermometry (S-r = 2.0% K-1, delta T = 0.121 K at 363 K). The applicability of the proposed SBR model is demonstrated using a flexible thin-film for accurate and real-time temperature detection at local hotspots in electronic components.