The development of organic solid-state luminescent materials, especially those sensitive to aggregation microenvironment, is critical for their applications in devices such as pressure-sensitive elements, sensors, and photoelectric devices. However, it still faces certain challenges and a deep understanding of the corresponding internal mechanisms is required. Here, we put forward an unconventional strategy to explore the pressure-induced evolution of the aggregation microenvironment, involving changes in molecular conformation, stacking mode, and intermolecular interaction, by monitoring the emission under multiple excitation channels based on a luminogen with aggregation-induced emission characteristics of di(p-methoxylphenyl)dibenzofulvene. Under three excitation wavelengths, the distinct emission behaviors have been interestingly observed to reveal the pressure-induced structural evolution, well consistent with the results from ultraviolet-visible absorption, high-pressure angle-dispersive X-ray diffraction, and infrared studies, which have rarely been reported before. This finding provides important insights into the design of organic solid luminescent materials and greatly promotes the development of stimulus-responsive luminescent materials.

The ionic transport properties of solid electrolyte LaF3 was systematically studied under high pressures up to 30.6 GPa with alternate-current impedance spectra measurements and first-principles calculations. From impedance spectra measurements,...

Impedance spectroscopy (IS) is an indispensable method of exploring electrical properties of materials. In this review, we provide an overview on the specific applications of IS measurement in the investigations of various electrical properties of materials under high pressure, including electric conduction in bulk and grain boundary, dielectric properties, ionic conduction, and electrostrictive effect. Related studies are summarized to demonstrate the method of analyzing different electrical transport processes with various designed equivalent circuits of IS and reveal some interesting phenomena of electrical properties of materials under high pressure.

The ionic transport properties of bismuth oxide (Bi 2 O 3 ) were investigated under high pressures with impedance spectrum and Raman spectrum measurements. It was found that Bi 2 O 3 is a pure ionic conductor below 9.0 GPa. Its pressure-dependent ionic conduction is determined by the diffusion rate of O 2− ions. Above 9.0 GPa, the number of O 2− ions that participate in electrical transportation are reduced rapidly by the pressureinduced distortion of crystal lattice, which becomes the essential factor to affect the ionic conduction. Most importantly, electronic conduction began to appear in the transportation process and coexist with the ionic conduction at 9.0 GPa indicating a few of originally localized electrons are involved in the electrical transportation due to the enhancement in distorted intension of Bi polyhedrons. Meanwhile, from the impedance spectra studies, it was also known that the electrical transport behaviors of Bi 2 O 3 can be tuned by the frequency of input signals. At high frequencies, Bi 2 O 3 behaves like an ionic solid electrolyte, but at low frequencies, it behaves like an electronic resistor.