Breakthrough Boost of Stokes Fluorescence from Er3+ in Perovskites for Flexible Temperature Sensing

Perovskites with ultra-low phonon energy have excellent radiation properties, while the population distribution of its luminescent initial state needs to be facilitated to further optimize the stokes fluorescence of Er3+ under high-energy photons excitation. Herein, UV excitability of Er3+ is remodeled by building an energy transfer channel from Sb3+ to Er3+ in Cs2NaInCl6 (CNIC) microcrystal to realize the enhancement of stokes fluorescence of Er3+. Under UV excitation, the breakthrough boost of Er3+ was observed in Cs2NaInCl6:Sb3+-Er3+ (CNIC:Sb-Er), and the sensitization coefficient from Sb3+ to Er3+ in CNIC was derived to be as high as 112. Moreover, CNIC:Sb-Er was embedded into fibers to enhance the crystal stability and the composite flexibility, which formed fluorescence fibers with strong radiation transition probability. Finally, a high-precision temperature sensing was achieved based on FIR (fluorescence intensity ratios) technology, and the maximum relative sensitivities of CNIC:Sb-Er phosphors and CNIC:Sb-Er/PAN fibers reach 1.13 %K-1 and 1.10 %K-1, respectively, indicating that CNIC:Sb-Er and CNIC:Sb-Er/PAN fibers have potential applications in optical temperature sensors.