Ultrasensitive Optical Thermometry via Inhibiting the Energy Transfer in Zero-Dimensional Lead-Free Metal Halide Single Crystals

Abstract

Self-referencing optical thermometry based on the fluorescence intensity ratio (FIR) have drawn extensive attention as a result of their high sensitivity and non-invasively fast response to temperature. However, it is a great challenge for luminescent materials to achieve simultaneously high absolute and relative temperature sensitivity based on the FIR technique. Herein, we developed a novel optical thermometer by designing hybrid leadfree metal halide (TTPhP) 2 MnCl 4 :Sb 3+ (TTPhP + = tetraphenylphosphonium cation) single crystals with multimodal photoluminescence (PL). The large TTPhP + organic chain resulted in isolated [MnCl 4 ] 2− and [SbCl 5 ] 2− in the single crystal, which leads to a negligible energy trasfer process within them. Therefore, the two PL bands (band 1 from [MnCl 4 ] 2− ) with a peak at 518 nm and band 2 (from [SbCl 5 ] 2 ) with a peak at 640 nm exhibit different thermalquenching effects, which resulted in excellent temperature sensitivity, with the maximum absolute and relative sensitivities reaching 0.236 K −1 and 3.77% K −1 in a temperature range from 300 to 400 K. Both the absolute and relative sensitivities are among the highest values for luminescence thermometry.

Reversible human-temperature-responsive luminescence switching in a Mn(ii)-based metal halide

“…The PLE spectrum splits into three groups of distinct bands between 250 and 500 nm, originating from the optical transition from 6 A 1 to the excited states. In addition, the TRPL delay curve at 310 K is well fitted by a single-exponential fitting function, and the average lifetime is 253.41 ms, agreeing well with the forbidden nature of the 4 T 1 (G) -6 A 1 (S) transition in tetrahedrally coordinated Mn(II) ions (Fig. S10 and Table S3, ESI †).…”

“…S8 (ESI †), the average R value decreases from 2.50 Å to 2.47 Å after heating, which causes the increase in D value, and then leads to larger d-d splitting of Mn 2+ ions. The energy difference for the 4 T 1 (G) -6 A 1 (S) transition is reduced as well, resulting in the PL redshift of the heated sample. At the same time, a sharp drop in the PL intensity between 306 K and 308 K was observed, which can be ascribed to the ordered-disordered phase transition.…”

“…Stimuli-responsive luminescent materials, with a specific response to external stimuli such as light, 1 pressure, 2 solvent molecules, 3 and heat, 4,5 have attracted extensive research interest and have shown wide application potentials in information storage, [6][7][8] chemical sensing, [9][10][11] and anti-counterfeiting. [12][13][14][15] In particular, thermosensitive materials are praised for their simple heating device requirement, highlighting their applications in thermal imaging, and thermometers.…”

The Effects of Mono- and Bivalent Linear Alkyl Interlayer Spacers on the Photobehavior of Mn(II)-Based Perovskites

“…We first examine the temperature effect on the emission spectrum of P2. Recent reports have shown that a change in the temperature induces a conversion from one Mn(II) configuration to another one [ 31 , 69 , 70 , 71 ]. This effect is reflected in the emission color that switches from green to orange/red when the temperature increases, and the reverse when the temperature decreases [ 31 , 69 ].…”

“…However, we did not observe any orange/red emission, the signature of the Mn(II) octahedral environment, as recorded for P1 ( Figure 2 A). Thus, we suggest that the decrease in the emission intensity of P2 upon increasing the temperature is rather due to an increase in the non-radiative processes, which are enhanced when electron-phonon interactions increase [ 31 , 71 ]. Notice that we did not observe any change in the excitation spectra upon increasing the temperature by almost 100 °C, which indicates that the emitters of P2 are originating from the same ground state population ( Figure S1 ).…”