Chiral perovskites have emerged as a significant class of materials showing promising optoelectronic and spintronic applications. Reports of chiral perovskite ferroelectrics, however, have been scarce. In this work, we have successfully synthesized homochiral lead-iodide perovskite ferroelectrics [(R)-N-(1-phenylethyl)ethane-1,2-diaminium]PbI and [(S)-N-(1-phenylethyl)ethane-1,2-diaminium]PbI by introducing a methyl group into the organic cation of the parent (N-benzylethane-1,2-diaminium)PbI . Vibrational circular dichroism spectra identify the chiral mirroring relationship. They both undergo 222F2-type paraelectric-ferroelectric behavior at around 378 K coupled with clear ferroelastic domain "ON/OFF" switching. Besides, they exhibit an evident thermochromism with color change from orange-yellow to orange-red. To our knowledge, the discovery of integrated ferroelectricity, ferroelasticity, and reversible thermochromism in chiral perovskites is unprecedented.
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http://dx.doi.org/10.1002/anie.202102195 | DOI Listing |
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December 2024
Dalian National Laboratory for Clean Energy, iChEM, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, P. R. China.
Formamidine lead iodide (FAPbI) quantum dots (QDs) have attracted great attention as a new generation of photovoltaic material due to their long carrier diffusion length, benign ambient stability, and light-harvesting ability. However, its large surface area with inherent thermodynamic instability and highly defective ionic termination are still major obstacles to fabricating high-performance devices. Herein, a metallic ion dopant is developed to post-treat FAPbI QDs immediately after their fabrication by using a metal-glutamate salt solution.
View Article and Find Full Text PDFACS Nano
December 2024
Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, Genova 16163, Italy.
We report the synthesis of ethylammonium lead iodide (EAPbI) colloidal nanocrystals as another member of the lead halide perovskites family. The insertion of an unusually large -cation (274 pm in diameter) in the perovskite structure, hitherto considered unlikely due to the unfavorable Goldschmidt tolerance factor, results in a significantly larger lattice parameter compared to the Cs-, methylammonium- and formamidinium-based lead halide perovskite homologues. As a consequence, EAPbI nanocrystals are highly unstable, evolving to a nonperovskite δ-EAPbI polymorph within 1 day.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Univ Rennes, ENSCR, CNRS, ISCR-UMR6226, Université de Rennes, Rennes 35042, France.
Metal halide perovskites, including some of their related perovskitoid structures, form a semiconductor class of their own, which is arousing ever-growing interest from the scientific community. With halides being involved in the various structural arrangements, namely, pure corner-sharing MX (M is metal and X is halide) octahedra, for perovskite networks, or alternatively a combination of corner-, edge-, and/or face-sharing for related perovskitoids, they represent the ideal probe for characterizing the way octahedra are linked together. Well known for their inherently large quadrupolar constants, which is detrimental to the resolution of nuclear magnetic resonance spectroscopy, most abundant halide isotopes (Cl, Br, I) are in turn attractive for magnetic field-free nuclear quadrupolar resonance (NQR) spectroscopy.
View Article and Find Full Text PDFJ Phys Chem Lett
December 2024
Materials Physics Center, CSIC-UPV/EHU, Paseo de Manuel Lardizabal, 5, 20018 Donostia - San Sebastian, Spain.
Hybrid perovskites exhibit complex structures and phase behavior under different thermodynamic conditions and chemical environments, the understanding of which continues to be pivotally important for tailoring their properties toward improved operational stability. To this end, we present for the first time a comprehensive neutron and synchrotron diffraction investigation over the pressure-temperature phase diagram of the paradigmatic hybrid organic-inorganic perovskite methylammonium lead iodide (MAPbI). This ambitious experimental campaign down to cryogenic temperatures and tens of kilobars was supported by extensive molecular dynamics simulations validated by the experimental data, to track the structural evolution of MAPbI under external physical stimuli at the atomic and molecular levels.
View Article and Find Full Text PDFSmall
December 2024
School of Energy Science and Engineering, University of Science and Technology of China, Hefei, 230026, P. R. China.
Flexible perovskite solar cells (FPSCs) have great promise for applications in wearable technology and space photovoltaics. However, the unpredictable crystallization of perovskite on flexible substrates results in significantly lower efficiency and mechanical durability than industry standards. A strategy is investigated employing the polymer electrolyte poly(allylamine hydrochloride) (PAH) to regulate crystallization and passivate defect states in perovskite films on flexible substrates.
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