A hybrid organic–inorganic compound, (pyrrolidinium)MnBr3
, distinguished from rare earth (RE)‐doped inorganic perovskites, is discovered as a new member of the ferroelectrics family, having ...excellent luminescent properties and relatively large spontaneous polarization of 6 μC cm−2, as well as a weak ferromagnetism at about 2.4 K. With a quantum yield of >28% and emission lifetime >0.1 ms, such multiferroic photoluminescence is a suitable candidate for future applications in luminescence materials, photovoltaics, and magneto‐optoelectronic devices.
Molecular piezoelectrics are highly desirable for their easy and environment-friendly processing, light weight, low processing temperature, and mechanical flexibility. However, although 136 years ...have passed since the discovery in 1880 of the piezoelectric effect, molecular piezoelectrics with a piezoelectric coefficient
comparable with piezoceramics such as barium titanate (BTO; ~190 picocoulombs per newton) have not been found. We show that trimethylchloromethyl ammonium trichloromanganese(II), an organic-inorganic perovskite ferroelectric crystal processed from aqueous solution, has a large
of 185 picocoulombs per newton and a high phase-transition temperature of 406 kelvin (K) (16 K above that of BTO). This makes it a competitive candidate for medical, micromechanical, and biomechanical applications.
1,4‐Diazabicyclo2.2.2octane (dabco) and its derivatives have been extensively utilized as building units of excellent molecular ferroelectrics for decades. However, the homochiral dabco‐based ...ferroelectric remains a blank. Herein, by adding a methyl (Me) group accompanied by the introduction of homochirality to the H2dabco2+ in the non‐ferroelectric H2dabcoTFSA2 (TFSA=bis(trifluoromethylsulfonyl)ammonium), we successfully designed enantiomeric ferroelectrics R and S‐2‐Me‐H2dabcoTFSA2. The two enantiomers show two sequential phase transitions with transition temperature (Tc) as high as 405.8 K and 415.8 K, which is outstanding in both dabco‐based ferroelectrics and homochiral ferroelectrics. To our knowledge, R and S‐2‐Me‐H2dabcoTFSA2 are the first examples of dabco‐based homochiral ferroelectrics. This finding opens an avenue to construct dabco‐based homochiral ferroelectrics and will inspire the exploration of more eminent enantiomeric molecular ferroelectrics.
The first examples of homochiral dabco‐based (dabco=1,4‐diazabicyclo2.2.2octane) ferroelectrics, R‐ and S‐2‐Me‐H2dabcoTFSA2 (TFSA=bis(trifluoromethylsulfonyl)ammonium), were designed from the non‐ferroelectric H2dabcoTFSA2. They show two phase transitions with a transition temperature (Tc) up to 405.8 K and 415.8 K, higher than the Tc of most dabco‐based or homochiral ferroelectrics.
COVID-19 is associated with 5.1% mortality. Although the virological, epidemiological, clinical, and management outcome features of COVID-19 patients have been defined rapidly, the inflammatory and ...immune profiles require definition as they influence pathogenesis and clinical expression of COVID-19. Here we show lymphopenia, selective loss of CD4+ T cells, CD8+ T cells and NK cells, excessive T-cell activation and high expression of T-cell inhibitory molecules are more prominent in severe cases than in those with mild disease. CD8+ T cells in patients with severe disease express high levels of cytotoxic molecules. Histochemical studies of lung tissue from one fatality show sub-anatomical distributions of SARS-CoV-2 RNA and massive infiltration of T cells and macrophages. Thus, aberrant activation and dysregulation of CD8+ T cells occur in patients with severe COVID-19 disease, an effect that might be for pathogenesis of SARS-CoV-2 infection and indicate that immune-based targets for therapeutic interventions constitute a promising treatment for severe COVID-19 patients.
Molecular ferroelectrics are highly desirable for their easy and environmentally friendly processing, light weight, and mechanical flexibility. We found that diisopropylammonium bromide (DIPAB), a ...molecular crystal processed from aqueous solution, is a ferroelectric with a spontaneous polarization of 23 microcoulombs per square centimeter close to that of barium titanate (BTO), high Curie temperature of 426 kelvin (above that of BTO), large dielectric constant, and low dielectric loss. DIPAB exhibits good piezoelectric response and well-defined ferroelectric domains. These attributes make it a molecular alternative to perovskite ferroelectrics and ferroelectric polymers in sensing, actuation, data storage, electro-optics, and molecular or flexible electronics.
Hybrid organo–metal halide perovskite materials, such as CH3NH3PbI3, have been shown to be some of the most competitive candidates for absorber materials in photovoltaic (PV) applications. However, ...their potential has not been completely developed, because a photovoltaic effect with an anomalously large voltage can be achieved only in a ferroelectric phase, while these materials are probably ferroelectric only at temperatures below 180 K. A new hexagonal stacking perovskite‐type complex (3‐pyrrolinium)(CdCl3) exhibits above‐room‐temperature ferroelectricity with a Curie temperature Tc=316 K and a spontaneous polarization Ps=5.1 μC cm−2. The material also exhibits antiparallel 180° domains which are related to the anomalous photovoltaic effect. The open‐circuit photovoltage for a 1 mm‐thick bulky crystal reaches 32 V. This finding could provide a new approach to develop solar cells based on organo–metal halide perovskites in photovoltaic research.
Changing phases: A hexagonal stacking organo–metal halide perovskite‐type complex (3‐pyrrolinium)(CdCl3) was designed. It shows above‐room‐temperature ferroelectricity with a Curie temperature Tc=316 K, an anomalous photovoltaic effect with an open‐circuit voltage of 32 V, and the formation of stripe‐like electric domains as a result of spontaneous polarization measured by piezoresponse force microscopy (see picture).
Optical‐electrical duple bistable switches are those that enable simultaneous conversion of both optical and electrical signals in one device to realize seamless integration. Herein, ...imidazolium‐FCrO3 can be prepared into a large‐size single crystal and ultraflexible thin film with ultrahigh unidirectionality of (0 0 4) and is characterized through scanning electron microscopy (SEM), atomic force microscopy (AFM), powder X‐ray diffraction, etc. Both the thin film and crystal display synchronously eximious optoelectronic duple characteristics (dielectric and nonlinear optical second harmonic generation (SHG) bistable switching ON/OFF), with a record‐high SHG contrast of ≈250 (2.0 times that of KDP, potassium dihydrogen phosphate, exceeding all the known molecular materials/crystalline switches, revealing its potential to obtain high‐efficiency signal‐to‐noise ratio), sensitive dielectric bistability, and remarkable switching antifatigue. These attributes make imidazolium‐FCrO3 a potential candidate in photoelectric seamless integration devices and flexible multifunctional devices.
Imidazolium‐FCrO3 is a novel optoelectronic duple bistable switch, which can be prepared into bulk single crystal and highly flexible thin film, exhibiting supereminent ON–OFF dielectric and nonlinear optical switching with obvious antifatigue in several cycles. The thin film has a preferred (0 0 4) orientation in accordance with the c‐axis of the crystal.
Luminescence of ferroelectric materials is one important property for technological applications, such as low-energy electron excitation. However, the vast majority of doped inorganic ferroelectric ...materials have low luminescent efficiency. The past decade has envisaged much progress in the design of both ferroelectric and luminescent organic–inorganic hybrid complexes for optoelectronic applications. The combination of ferroelectricity and luminescence within organic–inorganic hybrids would lead to a new type of luminescent ferroelectric multifunctional materials. We herein report a hybrid molecular ferroelectric, (pyrrolidinium)MnCl3, which exhibits excellent ferroelectricity with a saturation polarization of 5.5 μC/cm2 as well as intense red luminescence with high quantum yield of 56% under a UV excitation. This finding may extend the application of organic–inorganic hybrid compounds to the field of ferroelectric luminescence and/or multifunctional devices.
Existing learning-based atmospheric particle-removal approaches such as those used for rainy and hazy images are designed with strong assumptions regarding spatial frequency, trajectory, and ...translucency. However, the removal of snow particles is more complicated because they possess additional attributes of particle size and shape, and these attributes may vary within a single image. Currently, hand-crafted features are still the mainstream for snow removal, making significant generalization difficult to achieve. In response, we have designed a multistage network named DesnowNet to in turn deal with the removal of translucent and opaque snow particles. We also differentiate snow attributes of translucency and chromatic aberration for accurate estimation. Moreover, our approach individually estimates residual complements of the snow-free images to recover details obscured by opaque snow. Additionally, a multi-scale design is utilized throughout the entire network to model the diversity of snow. As demonstrated in the qualitative and quantitative experiments, our approach outperforms state-of-the-art learning-based atmospheric phenomena removal methods and one semantic segmentation baseline on the proposed Snow100K dataset. The results indicate our network would benefit applications involving computer vision and graphics.
2D hybrid halide double perovskites (HHDPs) have been demonstrated to be a promising alternative to conventional lead‐based halide perovskites as a new system of photoferroelectrics, due to their ...unique characteristics of environmental friendliness, favorable stability, and fascinating optoelectronic properties. Herein, for the first time, a 2D iodide double perovskite photoferroelectric is reported based on Ag/Sb ions, (4,4‐DFPD)4AgSbI8 (4,4‐DFPD = 4,4‐difluoropiperidinium), which possesses a high Curie temperature of 414 K (above BaTiO3), a large spontaneous polarization of 9.6 μC cm−2, ferroelectric photovoltaic effect, and photostrictive effect. Notably, to the best of the authors’ knowledge, the discovery of photostriction in HHDP photoferroelectrics is unprecedented. Moreover, (4,4‐DFPD)4AgSbI8 exhibits an impressive X‐ray responsivity, with a sensitivity as high as 704.8 μC Gyair−1 cm−2 at 100 V bias and a detection limit as low as 0.36 μGyair s−1 at 10 V bias, both of which outperform the current all HHDP photoferroelectrics. This work enriches the photoferroelectric family, and proves that Ag/Sb‐based HHDP photoferroelectrics are a promising candidate for the next‐generation optoelectronic devices.
The first silver/antimony‐based double perovskite photoferroelectric, (4,4‐difluoropiperidinium)4AgSbI8, is discovered, which exhibits ferroelectric photovoltaic effect and photostrictive effect under light radiation. Moreover, (4,4‐difluoropiperidinium)4AgSbI8 exhibits an exciting X‐ray responsivity including a sensitivity as high as 704.8 μC Gyair−1 cm−2 at 100 V bias and a detection limit as low as 0.36 μGyair s–1, both of which are the best among all HHDP photoferroelectrics.
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