High-resolution remote thermometry and thermography using luminescent low-dimensional tin-halide perovskites

Abstract

bolometric detectors, owing to advancements in MEMS-technologies (Micro-Electro-Mechanical Systems) 6,7 , have already entered the consumer electronics market, and are able to record thermal images with both high speed and high resolution. However, their thermographic performance, based on measurements of IR radiation intensity, is inherently limited by the transparency and emissivity/reflectivity of an observed object and, more importantly, by any material and medium (window, coating, matrix, solvent etc.) situated within the path between the detector and an object ( Fig. 1). As one of the major consequences, IR thermography cannot be easily combined with conventional optical microscopy or other enclosed optical systems such as cryostats or microfluidic cells.An alternative method for remote thermography, which is unhindered by enclosures or IRabsorptive media, utilizes temperature sensitive luminophores (i.e. fluorophores or phosphors) with PL in the visible spectral range (Fig. 1c) that are deposited onto, or incorporated into, the object of interest as temperature probes [8][9][10][11][12][13][14][15][16] . To probe an object's temperature, the luminophore is then excited by an ultraviolet or visible (UV-Vis) pulsed source (e.g. laser or light-emitting diode) and the temperature-dependent PL lifetime decay is then analyzed by time-resolving detectors.This PL-lifetime approach exhibits several benefits: the excitation power and, consequently the PL intensity, can be adjusted to a value appropriate for the dynamic range of the detector.Additionally, the use of UV-Vis light, rather than mid-to long-wavelength IR radiation, allows for the direct integration of this method with conventional optical spectroscopy and microscopy applied in biological studies and materials research. Furthermore, higher spatial resolutions can be obtained with visible light (400-700 nm) as the diffraction-limit is ca. 20-times sharper than for LWIR (7-14 µm); this potentially extends the utility of remote thermography to intracellular, in vitro, and in vivo studies 17 .

Optical Functional Units in Zero‐Dimensional Metal Halides as a Paradigm of Tunable Photoluminescence and Multicomponent Chromophores

“…Firstly, the PLE/PL peak of the Cl‐based samples have a significant blue shift compared to the Br‐based samples, which can be attributed to the excited states with higher energy of Cl‐based halides 12. In addition, as shown in Figure a,b, Cl‐based samples possess higher PLQY (MnCl sample and ZnCl sample even reached high PLQY of 83.3% and 90.8%, respectively, and the original spectra of the two compounds are provided in Figure S7, Supporting Information) and longer photoluminescence decay time, which is probably corresponding to the different emission quenching temperatures defined by the energy barrier for the non‐radiative decay 5a,13. As for the possible effect of M‐position cations, we also compared the PLQY (Figure 4a) and photoluminescence decay time (Figure 4b) with the variation of M cations.…”

“…In general, [PbX 6 ] 2− , [SnX 6 ] 2− , and [SbX 5 ] 2− (X = Cl, Br) are selected as the inorganic parts of 0D OIHMH to exhibit broad‐band emission originating from the so‐called self‐trapped excitons (STEs) 3b,5. Owing to the relatively large band gap, most of the above materials possess transparent body colors which facilitates their photoluminescence in the visible light region.…”

Structural Tunability and Diversity of Two‐Dimensional Lead Halide Benzenethiolate

“…It is found that the PL lifetime does not show dependence on excitation powers overawide range, which is consistent with recent papers on similar compounds. [23,24] This PL lifetimei sl ongert han that of most transition metal dichalcogenides and n = 12 Dh alide perovskite materials, [25] but much shorter than that of phosphorescent materials with triplet emission. [26,27] Recently,s imilar broad emission states with al arge Stokes shift have been observed in many halide-based perovskites and perovskite-like materials.…”

“…[26,27] Recently,s imilar broad emission states with al arge Stokes shift have been observed in many halide-based perovskites and perovskite-like materials. [24][25][26] It is generally believed that such intriguing emissions arise from self-trapped excitons associated with as oft and deformable crystal lattice. [24][25][26] Density functional theory (DFT) calculations were performed to better understand the bonding properties, energetics, and band structures.…”

“…[24][25][26] It is generally believed that such intriguing emissions arise from self-trapped excitons associated with as oft and deformable crystal lattice. [24][25][26] Density functional theory (DFT) calculations were performed to better understand the bonding properties, energetics, and band structures. Projected density of states (PDOS) and the band structure of Pb 2 I(S-C 6 H 5 ) 3 were obtained to reveal the characteristics of the valence bands and conduction bands.…”