Search

Piezochromic materials refer to a class of matters that alter their photoluminescence (PL) colors in response to the external stimuli, which exhibit promising smart applications in anti‐counterfeiting, optoelectronic memory and pressure‐sensing. However, so far, most reported piezochromic materials have been confined to organic materials or hybrid materials containing organic moieties with limited piezochromic range of less than 100 nm in visible region. Here, we achieved an intriguing piezochromism in all‐inorganic zero‐dimensional (0D) Cs3Cu2Cl5 nanocrystals (NCs) with a considerable piezochromic range of 232 nm because of their unique inorganic rigid structure. The PL energy shifted from the lowest‐energy red fluorescence (1.85 eV) to the highest‐energy blue fluorescence (2.83 eV), covering almost the entire visible wavelength range. Pressure‐modulated self‐trapped exciton emission between different energy levels of self‐trapped states within Cs3Cu2Cl5 NCs was the main reason for this piezochromism property. Note that the quenched emission, which is over five times more intense than that in the initial state, is retained under ambient conditions upon decompression. This work provides a promising pressure indicating material, particularly used in pressure stability monitoring for equipment working at extreme environments. [ABSTRACT FROM AUTHOR]

Warm WLED with high color rendering index (CRI) are greatly required for the widespread use of solid-state lighting especially indoors. Here, a remarkable improvement of CRI in alloyed CdS0.7Se0.3 QDs was achieved by pressure engineering. Notably, white light with enhanced CRI of 93, higher than pristine CRI of 47, was retained upon the complete release of pressure, accompanied by a color change from 'natural' (4298 K) to 'warm' white light (2170 K). Synchrotron ADXRD shows that CdS0.7Se0.3 QDs experienced an irreversible phase transition from the zinc blende phase to rocksalt structure. Warm white light with enhanced color rendering index of 93 is achieved by pressure processing, accompanied by a color change from 'natural' (4298 K) to 'warm' white light (2170 K). [ABSTRACT FROM AUTHOR]

SiO 2 is the major mineral substance in the upper mantle of the earth. Therefore, studies of the silica-coated materials under high-pressure are essential to explore the physical and chemical properties of the upper mantle. The silica-confined CsPbBr 3 nanocrystals (NCs) have recently attracted much attention because of the improved photoluminescence (PL) quantum yield, owing to the protection of silica shell. However, it remains considerable interest to further explore the relationship between optical properties and the structure of CsPbBr 3 @SiO 2 NCs. We systemically studied the structural and optical properties of the CsPbBr 3 @SiO 2 NCs under high pressure by using diamond anvil cell (DAC). The discontinuous changes of PL and absorption spectra occurred at ∼1.40 GPa. Synchrotron X-ray diffraction (XRD) studies of CsPbBr 3 @SiO 2 NCs under high pressure indicated an isostructural phase transformation at about 1.36 GPa, owing to the pressure-induced tilting of the Pb-Br octahedra. The isothermal bulk moduli for two phases are estimated about 60.0 ​GPa and 19.2 GPa by fitting the equation of state. Besides, the transition pressure point of CsPbBr 3 @SiO 2 NCs is slightly higher than that of pristine CsPbBr 3 NCs, which attributed to the buffer effect of coating silica shell. The results indicate that silica shell is able to enhance the stabilization without changing the relationship between optical properties and structure of CsPbBr 3 NCs. Our results were fascinated to model the rock metasomatism in the upper mantle and provided a new 'lithoprobe' for detecting the upper mantle. Image 1 • High-pressure behavior of CsPbBr 3 @SiO 2 NCs was adopted to investigate the properties of the upper mantle. • Pressure-induced PL and absorption of NCs experienced red shift in the 0~1.40 GPa, followed a blue shift above 1.40 GPa. • This study provided a new 'lithoprobe' for detecting the upper mantle. • CsPbBr 3 @SiO 2 NCs underwent an isostructural phase transition at approximately 1.40 GPa under high pressure. [ABSTRACT FROM AUTHOR]