Aggregation-Induced Fluorescence Enhancement for Efficient X-ray Imaging Scintillators and High-Speed Optical Wireless Communication

Abstract

Aggregation of some chromophores generates very strong fluorescence signals due to the tight molecular packing and highly restricted vibrational motions in the electronically excited states. Such an aggregation-induced emission enhancement enables great strides in biomedical imaging, security screening, sensing, and light communication applications. Here, we realized efficient utilization of a series of aggregation-induced emission luminogens (AIEgens) in X-ray imaging scintillators and optical wireless communication (OWC) technology. Ultrafast time-resolved laser spectroscopic experiments and high-level density functional theory (DFT) calculations clearly demonstrate that a significant increase in the rotational energy barrier in the aggregated state of AIEgens is observed, leading to highly restricted molecular vibrations and suppressed nonradiative processes. AIEgen-based scintillators exhibit a high X-ray imaging resolution of 16.3 lp mm −1 , making them excellent candidates for X-ray radiography and security inspections. In addition, these AIEgens show a broad -3-dB modulation bandwidth of ∼110 MHz and high net data rates of ∼600 Mb/s, demonstrating their high potential for application in the field of high-speed OWC.

Tunable Photoinduced Charge Transfer at the Interface between Benzoselenadiazole-Based MOF Linkers and Thermally Activated Delayed Fluorescence Chromophore

“…One of them presented a slow increase with a characteristic time constant of 4.6 ± 0.5 ps (31.8%) and slower decay of >4 ns (68.2%). The given time to achieve this increase can be associated with energy redistribution over the entire molecule after excitation, including through C�C vibrations, and, as with other systems with similar chemical structures, it can be considered the time required for an aggregate formation and other associated photophysics, 29,45,55 confirming that the origin of the tail observed in the steady-state absorption spectra is related to aggregation (Figure 1a,c). It should be noted that the C�C bond plays an important role in excited-state aggregate formation, allowing the entire molecule to adopt a planar structure due to the low rotational barrier around the C�C bond, which allows for easy stacking interactions between two molecules, as reported in another study involving a similar thiadiazole system.…”

Mn4+-Doped Fluoride Nanocrystals Enable High-Resolution Red-Emitting X-ray Imaging Screens

“…Recently, lead halide perovskite nanocrystals (NCs) with a lower synthesis temperature than that used for traditional scintillators, high X-ray absorption efficiency, intense radioluminescence, a low X-ray detection limit, and the ability to be processed from solution have been extensively studied as a new generation of X-ray scintillators. − In addition, reduced light scattering from the small particles in nanoscintillators ensures high spatial resolution . Despite their promising X-ray detection performance, the potential commercial applications of lead halide perovskite NCs are limited by the toxicity of lead, their low stability, and their strong reabsorption due to their small Stokes shift. − In this context, new lead-free metal halide materials with high X-ray performance have received increasing interest. ,− Thereby, a lead-free composition, high stability, narrow-band emission, high PLQY, large Stokes shift, and low reabsorption of Mn 4+ -doped hexafluoride NCs motivated us to test them for X-ray detection applications.…”

Stimuli-responsive flexible organic crystals

“…1 Since the concept of aggregation-induced luminescence (AIE) was proposed by Benzhong Tang's team in 2001, 64 AIE materials have been listed as one of the future advanced nanomaterials that would promote the ''future nano-luminescence revolution''. Subsequently, a series of aggregates with unique processes and properties were reported, such as aggregation-induced fluorescence enhancement (AIEE), [65][66][67] crystallization-induced luminescence (CIE), 68,69 and pure organic room temperature phosphorescence (PORTP). [70][71][72][73] The manufacture of these brilliant functional crystal materials has broadened the application prospects of AIE materials in many high-tech fields such as bioimaging, chemical sensing, optoelectronic devices, and intelligent stimulus-response systems.…”