High-sensitive thermometry and tunable dual-color luminescence based on effective energy transfer pathways of Er, Tm system

In this paper, the Er3+,Tm3+ co-doped La2Mo2O9 up-conversion luminescence phosphors are synthesized via solid state reaction. The luminescence characteristics and up-conversion processes of La2Mo2O9:Er3+,Tm3+ phosphors under the excitation of 980 and 1550 nm are investigated in detail. Tm3+ as an important energy transfer medium is the key to effectively improve the population of red-emitting energy levels (4F9/2) in the Er3+ sensitized system. Dual-color luminescence of green and red can be successfully achieved by controlling the concentration ratio of Er3+,Tm3+ co-doping under the dual-wavelength excitation. In addition, the optical temperature sensing ability of La2Mo2O9:Er3+,Tm3+ phosphors is analyzed by employing thermally coupled and non-thermally coupled energy levels. The obtained maximum absolute sensitivities are 8.33 × 10−3 K−1 under the 1550 nm excitation for non-thermally coupled energy levels. The La2Mo2O9:Er3+,Tm3+ phosphors with dual-color luminescence and high temperature sensing ability are the promising candidates in the fields of anti-counterfeiting and non-contact temperature sensing.