RESUMEN
The strained interface of core@shell nanocrystals (NCs) can effectively modulate the energy level alignment, thereby significantly affecting the optical properties. Herein, the unique photoluminescence (PL) response of doped Mn ions is introduced as a robust probe to detect the targeted pressure-strain relation of CdS@ZnS NCs. Results show that the core experiences actually less pressure than the applied external pressure, attributed to the pressure-induced optimized interface that reduces the compressive strain on core. The pressure difference between core and shell increases the conduction band and valence band offsets and further achieves the core@shell configuration transition from quasi type II to type I. Accordingly, the PL intensity of CdS@ZnS NCs slightly increases, along with a faster blue-shift rate of PL peak under low pressure. This study elucidates the interplay between external physical pressure and interfacial chemical stress for core@shell NCs, leading to precise construction of interface engineering for practical applications.
RESUMEN
Copper(I)-based halides have recently attracted increasing attention as a substitute for lead halides, owing to their nontoxicity, abundance, unique structure, and optoelectric properties. However, exploring an effective strategy to further improve their optical activities and revealing structure-optical property relationships still remain a great concern. Here, by using high pressure technique, a remarkable enhancement of self-trapped exciton (STE) emission associated with the energy exchange between multiple self-trapped states in zero-dimensional lead-free halide Cs3 Cu2 I5 NCs is successfully achieved. Furthermore, high-pressure processing endows the piezochromism of Cs3 Cu2 I5 NCs by experiencing a white light and a strong purple light emission, which is able to be stabilized at near-ambient pressure. The distortion of [Cu2 I5 ] clusters composing of tetrahedral [CuI4 ] and trigonal planar [CuI3 ] and the decreased Cu-Cu distance between the adjacent Cu-I tetrahedron and triangle are responsible for the significant STEs emission enhancement under high pressure. The experiments combined with first-principles calculations not only shed light on the structure-optical property relationships of [Cu2 I5 ] clusters halide, but also provide guidance for improving emission intensity that is highly desirable in solid-state lighting applications.
RESUMEN
Although seeking an effective strategy for further improving their optical properties is a great challenge, two-dimensional (2D) halide perovskites have attracted a significant amount of attention because of their performance. In this regard, the pressure-induced emission accompanied by a remarkable pressure-enhanced emission is achieved without a phase transition in 2D vacancy-ordered perovskite Cs3Bi2Cl9 nanocrystals (NCs). Note that the initial Cs3Bi2Cl9 NCs possess extremely strong electron-phonon coupling, leading to the easy annihilation of trapped excitons by the phonon. Upon compression, pressure could effectively suppress phonon-assisted nonradiative decay and give rise to an intriguing emission from "0" to "1". Both the weakened electron-phonon coupling and the relaxed halide octahedral distortion benefiting from the vacancy-ordered structure contributed to the subsequent enhanced emission. This work not only elucidates the underlying photophysical mechanism but also identifies pressure engineering as a robust means for improving their potential applications in environmentally friendly solid-state lighting at extremes.
RESUMEN
Maximizing the regeneration of singlet excitons remains a considerable challenge in deep-blue emission systems to obtain low-cost, high-efficiency fluorescent materials. However, the formation of the long-lifetime triplet excitons generally dominates the radiative process, making it greatly difficult to harvest deep-blue emission with high color purity because of the depression of singlet excitons. Here, a very bright deep-blue emission in double perovskite Cs2Na0.4Ag0.6InCl6 alloyed with Bi doping (CNAICB) was successfully achieved by pressure-driven reverse intersystem crossing (RISC), an abnormal photophysical process of energy transfer from the excited triplet state back to the singlet. Therein, the inherently broad emission of CNAICB was associated with the self-trapped excitons (STEs) at excited triplet states, whereas the radiative recombination of STEs populated in excited singlet states was responsible for the observed deep-blue emission. Moreover, the deep-blue emission corresponds to Commission Internationale de L'Eclairage (CIE) coordinates (0.16, 0.06) at 5.01 GPa, which meets the requirement of Rec. 2020 display standards. Likewise, pressure was introduced as an efficient tool to rule out the possibility of the recombination of free excitons and clarify the long-standing conventional dispute over the origin of the low-wavelength emission of Cs2AgInCl6. Our study not only demonstrates that pressure can be a robust means to boost the deep-blue emission but also provides deep insights into the structure-property relationship of lead-free CNAICB double perovskites.
RESUMEN
Pressure-induced emission (PIE) is extensively studied in halide perovskites or derivative hybrid halides. However, owing to the soft inorganic lattice of these materials, the intense emission is barely retained under ambient conditions, thus largely limiting their practical applications in optoelectronics at atmospheric pressure. Here, remarkably enhanced emission in microtubules of the 0D hybrid halide (C5 H7 N2 )2 ZnBr4 ((4AMP)2 ZnBr4 ) is successfully achieved by means of pressure treatment at room temperature. Notably, the emission, which is over ten times more intense than the emission in the initial state, is retained under ambient conditions upon the complete release of pressure. Furthermore, the pressure processing enables the tuning of "sky blue light" before compression to "cool daylight" with a remarkable quantum yield of 88.52% after decompression, which is of considerable interest for applications in next-generation lighting and displays. The irreversible electronic structural transition, induced by the steric hindrance with respect to complexly configurational organic molecules [4AMP], is highly responsible for the eventual retention of PIE and tuning of the color temperature. The findings represent a significant step toward the capture of PIE under ambient conditions, thus facilitating its potential solid-state lighting applications.
RESUMEN
High-pressure chemistry is an interdisciplinary science which uses high-pressure experiments and theories to study the interactions, reactions, and transformations among atoms or molecules. It has been extensively studied thus far and achieved rapid development over the past decades. However, what is next for high-pressure chemistry? In this Perspective, we mainly focus on the development of high-pressure experimental chemistry from our own viewpoint. An overview of the series of topics is as follows: (I) high pressure used as an effective tool to help resolve scientific disputes regarding phenomena observed under ambient conditions; (II) high-pressure reactions of interest to synthetic chemists; (III) utilizing chemical methods to quench the high-pressure phase; (IV) using high pressure to achieve what chemists want to do but could not do; (V) potential applications of in situ properties under high pressure. This Perspective is expected to offer future research opportunities for researchers to develop high-pressure chemistry and to inspire new endeavors in this area to promote the field of compression chemistry science.
RESUMEN
Low-dimensional halide perovskites easily suffer from the structural distortion related to significant quantum confinement effects. Organic tin bromide perovskite C4N2H14SnBr4 is a unique one-dimensional (1D) structure in which the edge sharing octahedral tin bromide chains [SnBr42-]∞ are embraced by the organic cations C4N2H142+ to form the bulk assembly of core-shell quantum wires. Some unusual phenomena under high pressure are accordingly expected. Here, an intriguing pressure-induced emission (PIE) in C4N2H14SnBr4 was successfully achieved by means of a diamond anvil cell. The observed PIE is greatly associated with the large distortion of [SnBr6]4- octahedral motifs resulting from a structural phase transition, which can be corroborated by in situ high-pressure photoluminescence, absorption, and angle-dispersive X-ray diffraction spectra. The distorted [SnBr6]4- octahedra would accordingly facilitate the radiative recombination of self-trapped excitons (STEs) by lifting the activation energy of detrapping of self-trapped states. First-principles calculations indicate that the enhanced transition dipole moment and the increased binding energy of STEs are highly responsible for the remarkable PIE. This work will improve the potential applications in the fields of pressure sensors, trademark security, and information storage.
