The electron-doping-induced phase transition of a prototypical perovskite SmNiO induces a large and non-volatile optical refractive-index change and has great potential for active-photonic-device applications. Strong optical modulation from the visible to the mid-infrared is demonstrated using thin-film SmNiO . Modulation of a narrow band of light is demonstrated using plasmonic metasurfaces integrated with SmNiO .
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http://dx.doi.org/10.1002/adma.201601204 | DOI Listing |
ACS Nano
January 2025
School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China.
Twisted halide perovskite bilayers, a type of moiré material, show square moiré patterns with exciting optical properties. Atomic-scale structure analysis and its correlation with properties are difficult to achieve due to the extreme sensitivity of organic-inorganic halide perovskites to the illuminated electron beam in conventional/scanning transmission electron microscopy. Here, we developed a low-dose exit wave reconstruction methodology with a real-space resolution of one angstrom at ∼50 e/Å, which recovers the phase information on the moiré fringes in CHNHPbI (MAPbI) twisted perovskite bilayers at atomic scale, enabling detailed structural analysis of defects and corresponding strain distribution in such moiré materials.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States.
In two-dimensional (2D) chiral metal-halide perovskites (MHPs), chiral organic spacers induce structural chirality and chiroptical properties in the metal-halide sublattice. This structural chirality enables reversible crystalline-glass phase transitions in (-NEA)PbBr, a prototypical chiral 2D MHP where NEA represents 1-(1-naphthyl)ethylammonium. Here, we investigate two distinct spherulite states of (-NEA)PbBr, exhibiting either radial-like or stripe-like banded patterns depending on the annealing conditions of the amorphous film.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Department of Materials Science and Engineering, Feng Chia University, Taichung City, 40724, Taiwan.
The unique optical properties of perovskite quantum dots (PQDs), particularly the tunable photoluminescence (PL) across the visible spectrum, make them a promising tool for chlorinated detection. However, the correlation between the fluorescence emission shift behavior and the interface of phase transformation in PQDs has not been thoroughly explored. In this study, we synthesized CsPbBr PQDs via the hot-injection method and demonstrated their ability to detect chlorinated volatile compounds such as HCl and NaOCl through a halide exchange process between the PQDs' solid thin film and the chlorinated vapor phase.
View Article and Find Full Text PDFChem Mater
January 2025
Department of Chemistry and Nanoscience Center, University of Copenhagen, 2100 Copenhagen Ø, Denmark.
Bismuth ferrites, specifically perovskite-type BiFeO and mullite-type BiFeO, hold significant technological promise as catalysts, photovoltaics, and room-temperature multiferroics. However, challenges arise due to their frequent cocrystallization, particularly in the nanoregime, hindering the production of phase-pure materials. This study unveils a controlled sol-gel crystallization approach, elucidating the phase formation complexities in the bismuth ferrite oxide system by coupling thermochemical analysis and total scattering with pair distribution function analysis.
View Article and Find Full Text PDFSmall
January 2025
Department of Physics, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
In this study, we investigate how modulating organic spacers in perovskites influences their X-ray detection performance and reveal the mechanism of low-dose detection with high sensitivity using femtosecond-transient absorption spectroscopy (fs-TAS). Particularly, we employ N,N,N',N'-tetramethyl-1,4-phenylenediammonium (TMPDA) and N,N-dimethylphenylene-p-diammonium (DPDA) as organic spacers to synthesize 2D perovskite single crystals (SCs). We find that DPDA-based SCs exhibit reduced interplanar spacing between inorganic layers, leading to increased lattice packing.
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