Highly Sensitive Dual-Mode Optical Thermometry of Er³⁺/Yb³⁺ Codoped Lead-Free Double Perovskite Microcrystal

Abstract

In this Letter, erbium (Er 3+ ) and ytterbium (Yb 3+ ) codoped perovskite Cs 2 Ag 0.6 Na 0.4 In 0.9 Bi 0.1 Cl 6 microcrystal (MC) is synthesized and demonstrated systematically to the most prospective optical temperature sensing materials. A dual-mode thermometry based on fluorescence intensity ratio and fluorescence lifetime provides a self-reference and highly sensitive temperature measurement under dual wavelength excitation at a temperature from 300 to 470 K. Combined with the white-light emission derived from self-trapped excitons (STEs), the characteristic emission peak of Er 3+ ions can be observed under 405 nm laser excitation. The fluorescence intensity ratio (FIR) between perovskite and Er 3+ is used as temperature-dependent probe signal, of which maximum value for relative and absolute sensitivities reaches to 1.40% K −1 and 8.20 × 10 −2 K −1 . Moreover, Er 3+ luminescence becomes stronger with the feeding Yb 3+ increasing under 980 nm laser excitation. The energy transfer of Er 3+ and Yb 3+ is revealed by power-dependent photoluminescence (PL) spectroscopy, and the involved upconversion mechanism pertains to the two-photon excitation process. The results reveal that the Er 3+ /Yb 3+ codoped lead-free double perovskite MC is a good candidate for a thermometric material for the novel dual-mode design.

Splendid four-mode optical thermometry design based on thermochromic Cs3GdGe3O9:Er3+ phosphors

“…, where dFIR denotes the uncertainty on the FIR estimation. 17,27 The calculated minimum value of dT shown in Considering the discrepant trends of green and red emission intensities with the increasing temperature, construction of a FIR strategy referring to the 2 H 11/2 and 4 F 9/2 levels of Er 3+ , termed as NTCEL, 42 is also significant for the temperature readout. The values of FIR (I 536nm /I 660nm ) can be well fitted via the polynomial formula: 15,42…”

“…Considering the discrepant trends of green and red emission intensities with the increasing temperature, construction of a FIR strategy referring to the 2 H 11/2 and 4 F 9/2 levels of Er 3+ , termed as NTCEL, 42 is also significant for the temperature readout. The values of FIR ( I 536nm / I 660nm ) can be well fitted via the polynomial formula: 15,42 FIR = A 3 T 3 + A 2 T 2 + A 1 T + A 0 where A 3 , A 2 , A 1 and A 0 represent the fitting constants. The fitting results are exposed in Fig.…”

“…6(a), with the correlation R 2 reaching 99.40%. The relevant S A and S R can be determined by: 38,42 …”

“…Consequently, multi-mode luminescent thermometers are undoubtedly of high interest, and can enable the temperature monitoring signal to be more precise by integrating the superior temperature detection performance from different types of sensing modes. Dual-or three-mode optical thermometers have been developed continuously in recent years [33][34][35][36][37][38][39][40][41][42][43][44] and are mainly classified into four categories. One is the FIR techniques that combine TECL with NTECL.…”

“…One is the FIR techniques that combine TECL with NTECL. [41][42][43] The second one is the integration of FL with FIR from TECL. 34,40 The third one is the coupling of FL with FIR from NTECL.…”