Exploring Organic Metal Halides with Reversible Temperature‐Responsive Dual‐Emissive Photoluminescence

Abstract

The exceptional structural tunability of organic metal halides endows them with fascinating electronic and photophysical properties, providing much scope for applications.I nt his work, single crystalso ft he organic metal halide (C 4 H 9 NH 3 ) 2 MnI 4 are found to show reversible thermo-induced luminescent chromism within aw ide temperature range.T he (C 4 H 9 NH 3 ) 2 MnI 4 single crystal exhibits two emission peaks at 550 and 672 nm, which are assigned to ad -d transition of Mn 2 + -centered tetrahedra and self-trapped excitons, respectively.T he temperature-dependent emission color change is attributed to the thermo-induced trapping and detrapping process of the self-trapped exciton. (C 4 H 9 NH 3 ) 2 MnI 4 exhibits am aximum photoluminescence quantum efficiency of up to 68 %a t 70 8C. The disclosed interacted photoluminescence decay mechanisms may prove useful for the further designo fo rganic metal halidesfor optical thermometry.

Preparation and Applications of Carbon‐Based Fluorescent Nanothermometers

“…Nevertheless, as the temperature rises, the photoluminescence (PL) intensity of the most temperature‐sensitive carbon‐based materials changes, enabling temperature detection. [ 23–25,79–99 ] In general, the temperature‐response mechanism of carbon‐based fluorescent materials mainly consists of the change in surface states and molecular states, thermally activated nonradiative trapping, spectral shift, and broadening of the zero‐phonon line (ZPL). [ 5–18 ]…”

“…In recent years, fluorescent carbon‐based materials, represented by fluorescent NDs, fluorescent GQDs, fluorescent P‐dots, and fluorescent CDs, have been extensively investigated for the temperature measurement of cells and other living and nonliving organisms. [ 79–98 ] Based on the different fluorescence characteristics, the carbon‐based thermometers can be classified into two types: single‐wavelength fluorescent carbon‐based thermometers and dual‐wavelength fluorescent carbon‐based thermometers.…”

“…In terms of macroscopic temperature detection and the further development of polymer composite modification, the composite films have high application value. [ 92 ]…”

“…These advantages make the carbon‐based thermometers have plenty of applications, especially in non‐contact temperature detection for biology and biomedicine. [ 79–98 ] The carbon‐based thermometers can be divided into two wide categories based on their output signals: single emission and dual emission.…”

“…They show the following advantages: high optical absorptivity, adjustable fluorescent emission, chemical stability, well biocompatibility, and low toxicity. [ 5–99 ] Given these superior properties, they have been extensively discussed in bioimaging devices, biosensors, catalysts, photovoltaic devices, as well as fluorescent nanothermometers for spatially resolved temperature ( Figure ). [ …”