Direct detection of circularly polarized light (CPL) is a challenging task due to limited materials and ambiguous structure–property relationships that lead to low distinguishability of the light ...helicities. Perovskite ferroelectric semiconductors incorporating chirality provide new opportunities in dealing with this issue. Herein, a pair of 2D chiral perovskite ferroelectrics is reported, which have enhanced CPL detection performance due to interplays among lattice, photon, charge, spin, and orbit. The chirality‐transfer‐induced chiral&polar ferroelectric phase enhances the asymmetric nature of the photoactive sublattice and achieves a switchable self‐powered detection via the bulk photovoltaic effect. The single‐crystal‐based device exhibits a CPL‐sensitive detection performance under 430 nm with an asymmetric factor of 0.20 for left‐ and right‐CPL differentiation, about two times that of the pure chiral counterparts. The enhanced CPL detection performance is ascribed to the Rashba–Dresselhaus effect that originates from the bulk inversion asymmetry and strong spin–orbit coupling, shown with a large Rashba coefficient, which is demonstrated by density functional theory calculation and circularly polarized light excited photoluminescence measurement. These results provide new perspectives on chiral Rashba ferroelectric semiconductors for direct CPL detection and ferroelectrics‐based chiroptics and spintronics.
A pair of 2D chiral perovskite Rashba ferroelectric semiconductors is reported. The fabricated single‐crystal device responds to circularly polarized light (CPL) under 430 nm with an anisotropy factor of 0.20 for the left‐ and right‐CPL differentiation, about two times of reported pure chiral counterparts. The enhanced performance is ascribed to the Rashba–Dresselhaus effect with a large Rashba coefficient of 0.93 eV Å.
Multiferroics refer to materials with two or more ferroic orders in one phase within a specific temperature range, including ferroelectricity, ferroelasticity, and ferromagnetism which have been ...widely used in sensors, actuators, and memory devices. Among them, hybrid perovskites exhibiting multiferroicity are generally limited to low dimensions (0D–2D). Designing 3D lead‐free perovskite multiferroics remains a challenge due to Goldschmidt's tolerance factor limitation. Here, a multiferroic perovskite (R‐3AP)RbBr3 (1; 3AP = 3‐ammoniopyrrolidinium) is successfully synthesized by introducing homochirality to the 3D ferroelectric (Rac‐3AP)RbBr3, achieving both ferroelasticity and ferroelectricity. Compound 1 undergoes a structure phase transition at 401 K belonging to Aizu notation 432F2(s), which has 12 ferroelectric equivalent polarization directions and 6 polar axes. Furthermore, 1 exhibits reversible second harmonic generation switching effects. Moreover, while the temperature varies, the reversible and rapid changes of ferroelastic domains in 1 are observed using a polarizing microscope, indicating that it is a ferroelastic material. This work provides a practical method for designing and synthesizing molecule‐based multiferroics.
The work reports a 3D perovskite multiferroics (R‐3AP)RbBr3 (1) based on the 3D rubidium‐based ferroelectric (Rac‐3AP)RbBr3 by using the homochirality strategy. Compound 1 exhibits 432F2(s) ferroelectric–ferroelastic phase transition at 401 K. In addition, 1 exhibits a second harmonic generation (SHG) switch and multi‐axis ferroelectricity with a saturation polarization (Ps) value of 1.21 µC·cm−2.
Hybrid metal halides (HMHs) based phase transition materials have received widespread attention due to their excellent performance and potential applications in energy harvesting, optoelectronics, ...ferroics, and actuators. Nevertheless, effectively regulating the properties of phase transitions is still a thorny problem. In this work, two chiral lead‐free HMHs (R‐3FP)2SbCl5 (1; 3FP=3‐fluoropyrrolidinium) and (R‐3FP)2SbBr5 (2) were synthesized. By replacing the halide ions in the inorganic skeleton, the phase transition temperature of 2 changes with an increase of about 20 K, compared with 1. Meanwhile, both compounds display reversible dielectric switching properties. Through crystal structure analysis and Hirshfeld surface analysis, their phase transitions are ascribed to the disorder of the cations and deformation of the inorganic chains.
This article reports a pair of 1D lead‐free hybrid metal halides: (R‐3FP)2SbCl5 (1; 3FP=3‐fluoropyrrolidinium) and (R‐3FP)2SbBr5 (2) exhibit high temperature triggered structural phase transition and dielectric switching properties. By halogen substitution in the inorganic framework, the dielectric switch temperature of 2 increased about 20 K, compared with 1.
Abstract
Martensitic transformation, usually accompanied by ferroelastic and thermoelastic behaviors, is an interesting and useful mechanical-related property upon external stimuli. For molecular ...crystals, however, martensitic systems to show reversible stimuli-actuation behaviors are still limited because of a lack of designability and frequent crystal collapse due to large stress releases during the transformations. Here, a one-dimensional hybrid perovskite semiconductor (NMEA)PbI
3
(NMEA =
N
-methylethylammonium) was prepared by following a dimensionality reduction design principle. The crystal undergoes reversible ferroelastic and thermoelastic martensitic transformations, which are attributed to weak intermolecular interactions among the chains that easily trigger the interchain shearing movement. The actuation behavior occurring during the phase transition is very close to room temperature and demonstrated to behave as a mechanical actuator for switching. This work provides an effective approach to designing molecular actuators with promising applications in next-generation intelligence devices.
Accidental oil leaks and spills can often result in severe soil and groundwater pollution. In situ chemical oxidation (ISCO) is a powerful and efficient remediation technology. In this review, the ...applications and recent advances of three commonly applied in-situ oxidants (hydrogen peroxide, persulfate, and permanganate), and the gap in remediation efficiency between lab-scale and field-scale applications is critically assessed. Feasible improvements for these measures, especially solutions for the ‘rebound effect’, are discussed. The removal efficiencies reported in 108 research articles related to petroleum-contaminated soil and groundwater were analyzed. The average remediation efficiency of groundwater (82.7%) by the three oxidants was higher than that of soil (65.8%). A number of factors, including non-aqueous phase liquids, adsorption effect, the aging process of contaminants, low-permeability zones, and vapor migration resulted in a decrease in the remediation efficiency and caused the residual contaminants to rebound from 19.1% of the original content to 57.7%. However, the average remediation efficiency of ISCO can be increased from 40.9% to 75.5% when combined with other techniques. In the future, improving the utilization efficiency of reactive species and enhancing the contact efficiency between oxidants and petroleum contaminants will be worthy of attention. Multi-technical combinations, such as the ISCO coupled with phase-transfer, viscosity control, controlled release or natural attenuation, can be effective methods to solve the rebound problem.
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•In-situ chemical oxidation is an effective method for petroleum polluted sites.•The rebound of petroleum concentration prevents to reach the remediation goal.•The non-aqueous contaminants and matrix back diffusion are worthy of attention.•Other technologies can improve treatment efficiency of in-situ chemical oxidation.
Tuning phase transition temperature is one of the central issues in phase transition materials. Herein, we report a case study of using enantiomer fraction engineering as a promising strategy to tune ...the Curie temperature (T
) and related properties of ferroelectrics. A series of metal-halide perovskite ferroelectrics (S-3AMP)
(R-3AMP)
PbBr
was synthesized where 3AMP is the 3-(aminomethyl)piperidine divalent cation and enantiomer fraction x varies between 0 and 1 (0 and 1 = enantiomers; 0.5 = racemate). With the change of the enantiomer fraction, the T
, second-harmonic generation intensity, degree of circular polarization of photoluminescence, and photoluminescence intensity of the materials have been tuned. Particularly, when x = 0.70 - 1, a continuously linear tuning of the T
is achieved, showing a tunable temperature range of about 73 K. This strategy provides an effective means and insights for regulating the phase transition temperature and chiroptical properties of functional materials.
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•The groundwater body of the study area was in a highly saline reductive environment.•Nitrate concentration is higher than ammonium content, exceeding groundwater standard.•Microbial ...metabolism is the main contributor to fluorescent organic matter.•Cr, Ni, Zn, and Mo are mainly complexed with small molecular fluorescent matter.•Both organic and inorganic substances influence the fate and transport of PFCs.
Vegetable cultivation may cause groundwater pollution. This study investigated the characteristics of shallow groundwater pollution from agricultural activities in North China and the geochemical behavior of major pollutants. The results showed that the groundwater was in a highly saline reductive environment, and the concentration of nitrate was higher than that of ammonium. The humification degree of dissolved organic matter (DOM) varied at different sampling points. Sources of DOM in the groundwater were similar, and manure components leaching into groundwater enhanced microbial metabolism activities. DOM mainly comprised small molecules and easily degradable proteins as well as humic substances that were bound to proteinaceous substances. Concentrations of eight heavy metals detected did not exceed China’s drinking water standards. Correlation results showed that the characteristics of fluorescent organic matter could better reflect the status of groundwater pollution. Cr, Ni, Zn, and Mo were associated with DOM, mainly complexed with small molecular fluorescent organic matter. Organic carbon, nutrients and inorganic salts would influence the fate and transport of perfluorinated compounds in the groundwater. In the process of vegetable planting, organic manure should be applied through best practices, and supervision of the planting area is crucial for avoiding groundwater pollution.
Circular dichroism (CD) spectroscopy is a well-known and powerful technique widely used for distinguishing chiral enantiomers based on their differential absorbance of the right and left circularly ...polarized light. With the increasing demand for solid-state chiral optics, CD spectroscopy has been extended to elucidate the chirality of solid-state samples beyond the traditional solution state. However, due to the sample preparation differential, the CD spectra of the same compound measured by different researchers may not be mutually consistent. In this study, we employ solution, powder, thin-film, and single-crystal samples to explore the challenges associated with CD measurements and distinguish between genuine and fake signals. Rational fabrication of the solid-state samples can effectively minimize the macroscopic anisotropic nature of the samples and thereby mitigate the influence of linear dichroism (LD) and linear birefringence (LB) effects, which arise from anisotropy-induced differences in the absorbances and refractive indices. The local anisotropic and overall isotropic features of the high-quality thin-film sample achieve an optically isotropic state, which exhibits superior CD signal repeatability at the front and back sides at different angles by rotating the sample along the light path. In addition, sample thickness-induced CD signal overload and absorption saturation pose more severe challenges than the LBLD-induced amplified CD signal but are rarely focused on. The CD signal overload in the deep UV region leads to the presence of fake signals, while absorption saturation results in a complete loss of the CD signal. These findings help obtain accurate CD signals by a well-fabricated optically isotropic sample to avoid LDLB and optimize the sample thickness to avoid fake signals and no signals.
Circularly polarized luminescence (CPL) with polychromatic colors has been widely studied due to its great applications in chiroptical, optoelectronics, and spintronics. However, the realization of ...white CPL in single‐component solid‐state materials remains a great challenge and suffers from the incompatibility between high efficient luminescence and large asymmetric discrimination. Here, by exploiting self‐trapped exciton mechanism and chirality induction strategy, a pair of 1D chiral perovskites, (RR/SS‐DMPZ)PbBr4 (where DMPZ = cis‐2,5‐dimethylpiperazine divalent cation), is reported to achieve white CPL with both high quantum yield of 28.4% and large photoluminescence asymmetry factor |glum| of 2.32 × 10−2. The crystal structures are featured by 1D double‐chain structure composed of distorted octahedra with short PbPb distances as the structural origin of the high photoluminescence yield. The high |glum| value is caused by efficient chiral induction due to the multiple hydrogen bonds between the chiral host composed of the enantiopure organic cations containing two stereocenters and the inorganic emitting guest. The self‐trapped exciton emission mechanism is demonstrated by density functional theory calculations and variable‐temperature photoluminescence and femtosecond‐transient absorption spectroscopy studies. The photo‐luminescent white light‐emitting diodes exhibit good stability and can be used as single‐component white light emitters. This work provides applicable strategies to explore single‐component white CPL emitters.
A pair of single‐component circularly polarized white light emitters with an ultra‐broadband emission are successfully synthesized. The white circularly polarized light emission originates from the self‐trapped exciton mechanism. The perovskite enantiomers with a double 1D chain exhibit excellent performance with a high quantum yield (28.4%) and large photoluminescence asymmetry factor (2.32 × 10−2).
A two-dimensional (2D) organic–inorganic hybrid perovskite (OIHP) material with out-of-plane ferroelectricity is the key to the miniaturization of vertical-sandwich-type ferroelectric optoelectronic ...devices. However, 2D OIHP ferroelectrics with out-of-plane polarization are still scarce, and effective design strategies are lacking. Herein, we report a novel 2D Dion–Jacobson perovskite ferroelectric semiconductor synthesized by a rigid-to-flexible cationic tailoring strategy, achieving an out-of-plane polarization of 1.7 μC/cm2 and high photoresponse. Integrating out-of-plane ferroelectricity with excellent photoelectric properties affords a promising platform to investigate ferroelectricity-related effects in vertical optoelectronic devices.
