Energy transfer in Bi3+-Sm3+ co-doped phosphors for temperature sensing and imaging

Optical thermometry has the distinct superiority of non-invasive, non-contact, and high spatial resolution. However, the simultaneous improvement of temperature sensitivity and resolution remains challenging. Herein, the tunable emission colors can be realized via energy transfer in Bi3+-Sm3+ co-doped La3Ta0.8Sb0.2O7, which further applied for fluorescence temperature sensing and imaging. With the partial substitution of Sb5+ with Ta5+, the emission peak of La3SbO7:0.04Bi(3+) shiftes from 530 nm to 460 nm, together with a 2.1-fold enhancement of emission intensity. The emission shifted from bright blue to purple under 365 nm excitation based on the energy transfer. The energy transfer efficiency from Bi3+ to Sm3+ can reach 41.6 % via dipo-le-dipole interaction. The La3Ta0.8Sb0.2O7:(0.04Bi(3+),0.005Sm(3+)) phosphors exhibit maximum relative sensitivity (Sr) of 1.32 %K-1 (@498 K) and absolute sensitivity (Sa) of 0.059 K-1 (@417 K), which have excellent tem-perature resolution and repeatability. Thus, the energy transfer in co-coped phosphors can simultaneously improve the temperature sensitivity and resolution for fluorescence temperature sensing. Besides, the phosphor/ PDMS films can exhibit obvious thermochromic imaging.

Automated summary

This study demonstrates tunable emission colors and high sensitivity for fluorescence temperature sensing by co-doping Bi3+-Sm3+ in La3Ta0.8Sb0.2O7. The research also shows the thermochromic imaging effect of phosphor/PDMS films.