Advances in the Application of Perovskite Materials

Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allow metal halide perovskite to be employed in a wide variety of applications. This article provides a holistic review over the current progress and future prospects of metal halide perovskite materials in representative promising applications, including traditional optoelectronic devices(solar cells, light-emitting diodes, photodetectors, lasers), and cutting-edge technologies in terms of neuromorphic devices(artificial synapses and memristors) and pressure-induced emission. This review highlights the fundamentals, the current progress and the remaining challenges for each application, aiming to provide a comprehensive overview of the development status and a navigation of future research for metal halide perovskite materials and devices.

Pressure-induced emission from low-dimensional perovskites

White light emitting diodes from a single emitter is of sig-nificance in application of illumination and image display be-cause of avoiding the color instability in devices with mul-tiple emitters[1,2].Recently,as a single emitter,low-dimension-al halide perovskites have drawn great attention for their broadband solid-state lighting based on the radiative recom-bination of self-trapped excitons(STEs)and excellent device stability[3−8].The dimensionality reduction could effectively en-hance the deformability of octahedral framework and thus electron-phonon coupling strength,facilitating exciton self-trapping.However,low-dimensional perovskites cannot satis-fy the requirement of device commercialization due to the rare achievement of high photoluminescence quantum yield[9].Developing an effective strategy to improve the emis-sion and elucidating the underlying mechanism have be-come an urgent need.

Stability and band gap engineering of silica-confined lead halide perovskite nanocrystals under high pressure

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.

Pressure-induced emission(PIE)in halide perovskites toward promising applications in scintillators and solid-state lighting

High-pressure chemistry has provided a huge boost to the development of scientific community.Pressure-induced emission(PIE)in halide perovskites is gradually showing its unique charm in both pressure sensing and optoelectronic device applications.Moreover,the PIE retention of halide perovskites under ambient conditions is of great commercial value.Herein,we mainly focus on the potential applications of PIE and PIE retention in metal halide perovskites for scintillators and solid-state lighting.Based on the performance requirements of scintillator and single-component white light-emitting diodes(WLEDs),the significance of PIE and PIE retention is critically clarified,aiming to design and synthesize materials used for high-performance optoelectronic devices.This perspective not only demonstrates promising applications of PIE in the fields of scintillators and WLEDs,but also provides potential applications in display imaging and anti-counterfeiting of PIE materials.Furthermore,solving the scientific disputes that exist under ambient conditions is also simply discussed as an outlook by introducing high-pressure dimension to produce PIE.

Disulfide Crosslinking-Induced Aggregation:Towards Solid-State Fluorescent Carbon Dots with Vastly Different Emission Colors

Solid-state fluorescent multi-color carbon dots(SFM-CDs),prepared using the same precursor(s)without the need for dispersion in a solid matrix,are highly demanded for a wide range of applications.Herein,we report a microwave-assisted strategy for the prepara-tion of SFM-CDs with blue,yellow and red emissions within 5 min from the same precursors.The as-prepared B-CDs,Y-CDs,and R-CDs possessed bright fluorescence at 425 nm,550 nm,and 640 nm,and photoluminescence quantum yields(PLQYs)of 54.68%,17.93%,and 2.88%,respectively.The structure of SFM-CDs consisted of 5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-7-carboxylic acid(TPCA)immobilized on the surface of a carbon core,with the size of the carbon core and degree of disulfide crosslinking between CDs both increasing on going from the B-CDs to the R-CDs,as verified by mechanochromic experiments.The excellent solid-state fluorescence performance of the SFM-CDs allowed their utilization as the fluorescent converter layer in multi-color LEDs and white LEDs with a high color rendering index.

压力诱导发光,点亮未来

Photoluminescence intensity is a crucial parameter for evaluating the performance of optoelectronic devices.To date,efforts to optimize the emission properties of luminescent materials are continuously implemented,such as surface passivation with ligands or electronic structure modulation using heterojunctions.

High pressure, a protocol to identify the weak dihydrogen bonds:experimental evidence of C–H···H–B interaction

Pressure, as a thermodynamic parameter, provides an appropriate method to detect weak intermolecular interactions. The C–H···H–B dihydrogen bond is so weak that the experimental evidence of this interaction is still limited. A combination of in situ high pressure Raman spectra and angle-dispersive X-ray diffraction(ADXRD) experiments was utilized to explore the dihydrogen bonds in dimethylamine borane(DMAB). Both Raman and ADXRD measurements suggested that the crystal structure of DMAB is stable in the pressure region from 1 atm(1 atm=1.01325×10~5 Pa) to 0.54 GPa. The red shift of CH stretching and CH_3 distortion modes gave strong evidence for the existence of C–H···H–B dihydrogen bonds. Further analysis of Raman spectra and Hirshfeld surface confirmed our proposal. This work provided a deeper understanding of dihydrogen bonds.And we wish that high pressure could be applied to identify other unconfirmed hydrogen or dihydrogen bond.

High pressure supramolecular chemistry

High pressure supramolecular chemistry is a developing interdisciplinary field. The use of high pressure for the study and fabrication of supramolecular systems has been explored only in the past few years. Such studies would shed light on the nature of the structures and functions of the complex supramolecular architectures. In this review, systematic progress made in this field is introduced based on the recent achievements. Special attention is paid to pressure-driven novel properties and functions of supramolecular assemblies resulting from the changes of molecular conformations, intermolecular interactions and supramolecular arrangements under high pressure.

Whether or Not Emission of Cs4PbBr6 Nanocrystals:High-Pressure Experimental Evidence

The origin of green emission in the zero-dimensional(0D)perovskite Cs4PbBr6 nanocrystals(NCs)remains a considerable debate.Herein,an approach involving a combination of high-pressure experiments and theoretical simulation was employed to elucidate the controversial origin of photoluminescence from emissive Cs4PbBr6 NCs(E416).Results obtained from first-principles density functional theory(DFT)calculations,as implemented in the Vienna ab initio simulation package codes,implied that the photoluminescence energies from bromine vacancy decreased persistently with pressure.Experimentally,the photoluminescence energies tended to decrease in the low-pressure region,followed by an increase beyond∼1.4 GPa.While the emergent disagreement between the first-principles calculation and highpressure experiment excludes the possibility of vacancy-tuning,the consistent change observed in the pressure-dependent emission between E416 and CsPbBr_(3) NCs offered a reliable interpretation for the occurrence of green emission from a CsPbBr_(3) impurity embedded in the Cs4PbBr6 matrix.Further comprehensive analysis demonstrated that the strong green emission of E416 NCs originated from the impurity CsPbBr_(3) NCs embedded in Cs4PbBr6 matrix.Our study represents a significant step forward to a deeper understanding of the emissive origins of Cs4PbBr6 NCs and promotes the application of this novel strategy in light-emitting devices.

Unravelling a solution-based formation of single- crystalline kinked wurtzite nanowires： The case of MnSe

The search for a novel strategy to sculpt semiconductor nanowires （NWs） at the atomistic scale is crucial for the development of new paradigms in optics, electronics, and spintronics. Thus far, the fabrication of single-crystalline kinked semiconductor NWs has been achieved mainly through the vapor-liquid-solid growth technique. In this study, we developed a new strategy for sculpting single-crystalline kinked wurtzite （WZ） MnSe NWs by triggering the nonpolar axial-oriented growth, thereby switching--at the atomistic scale---the NW growth orientation along the nonpolar axes in a facile solution-based procedure. This presents substantial challenges owing to the dominant polar c axis growth in the solution-based synthesis of one-dimensional WZ nanocrystals. More significantly, the ability to continuously switch the nonpolar axial-growth orientation allowed us to craft the kinking landscape of types 150°, 120°, 90°, and 60°. A probabilistic analysis of kinked MnSe NWs reveals the correlations of the synergy and interplay between these two sets of nonpolar axial growth-orientation switching, which determine the actual kinked motifs. Furthermore, discriminating the side-facet structures of the kinked NWs significantly strengthened the spatially selected interaction of Au nanoparticles. We envisage that such a facile solution-based strategy can be useful for synthesizing other single-crystalline kinked WZ-type transition-metal dichalcogenide NWs to develop novel functional materials with finely tuned properties.