Studying defect formation and evolution in MethylAmmonium lead Iodide (MAPbI) perovskite layers has a bottleneck in the softness of the matter and in its consequent sensitivity to external solicitations. Here we report that, in a polycrystalline MAPbI layer, Pb-related defects aggregate into nanoclusters preferentially at the triple grain boundaries as unveiled by Transmission Electron Microscopy (TEM) analyses at low total electron dose. Pb-clusters are killer against MAPbI integrity since they progressively feed up the hosting matrix. This progression is limited by the concomitant but slower transformation of the MAPbI core to fragmented and interconnected nano-grains of 6H-PbI that are structurally linked to the mother grain as in strain-relaxed heteroepitaxial coupling. The phenomenon occurs more frequently under TEM degradation whilst air degradation is more prone to leave uncorrelated [001]-oriented 2H-PbI grains as statistically found by X-Ray Diffraction. This path is kinetically costlier but thermodynamically favoured and is easily activated by catalytic species.
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http://dx.doi.org/10.1038/s41467-019-09909-0 | DOI Listing |
ACS 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 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 PDFSci Adv
December 2024
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
Metal halide perovskite single crystals (SCs) emerge as a promising candidate for ionizing radiation detection. The realization of top-performing radiation detectors typically relies on careful crystal selection from broad candidate groups, as residual strain remains unavoidable during the SC growth process, which often leads to the formation of ferroelastic domains with varied orientations. Here, we introduce an in-line tempering strategy to alleviate microstrain and homogenize the domain orientation across methylammonium lead iodide (MAPbI) perovskite SCs.
View Article and Find Full Text PDFJ Synchrotron Radiat
January 2025
Department of Physics, Masinde Muliro University of Science and Technology, Kakamega, Kenya.
3D mixed perovskites have achieved substantial success in boosting solar cell efficiency, but the complicated perovskite crystal formation pathway remains mysterious. Here we present detailed crystallization kinetics of mixed perovskites FAMAPb(IBr), where FA is formamidinium and MA is methylammonium, with the addition of Cs to form a triple cation perovskite (3-CAT), in a comparison with the perovskite building block MAPbI (MAPI) via static grazing-incidence wide-angle X-ray scattering (GIWAXS) and micro-diffraction measurements. Spin-coated films produced α-perovskite peaks with no PbI or δ-intermediate phases, which was a promising result for the 3-CAT perovskite from micro-diffraction measurements.
View Article and Find Full Text PDFLangmuir
December 2024
Department of Geophysics, College of Remote Sensing and Geophysics, Al-Karkh University of Science, Baghdad 10011, Iraq.
Carbon nanomaterials (graphene, carbon nanotubes, and graphene oxide) have potential applications for optoelectronics, thanks to their superior electronic and optical characteristics. The remarkable stability of carbon-based perovskite solar cells (PSCs) has attracted significant attention. Herein, a fluorine-doped carbon nanotube (F-CNT) is incorporated into the PSCs as a hole-transporting layer (HTL) in between methylammonium lead iodide (MAPbI) and the rear electrode to develop an effective MAPbI/HTL interface.
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