Atomic layer deposition offers outstanding film uniformity and conformality on substrates with high aspect ratio features. These qualities are essential for mixed-halide perovskite films applied in tandem solar cells, transistors and light-emitting diodes. The optical and electronic properties of mixed-halide perovskites can be adjusted by adjusting the ratios of different halides. So far ALD is only capable of depositing iodine-based halide perovskites whereas other halide processes are lacking. We describe six new low temperature (≤100 °C) ALD processes for PbCl and PbBr that are crucial steps for the deposition of mixed-halide perovskites with ALD. Lead bis[bis(trimethylsilyl)amide]-GaCl and -TiBr processes yield the purest, crystalline, uniform and conformal films of PbCl and PbBr respectively. We show that these two processes in combination with a PbI process from the literature deposit mixed lead halide films. The four less optimal processes revealed that reaction by-products in lead halide deposition processes may cause film etching or incorporate themselves into the film.
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http://dx.doi.org/10.1039/d2dt02216h | DOI Listing |
Phys Chem Chem Phys
February 2024
US Department of Energy, Ames National Laboratory, Ames, Iowa, 50011, USA.
Adv Sci (Weinh)
January 2024
Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong, 518055, China.
Two dimensional (2D) hybrid metal halides (HMHs) usually exhibit free excitonic (FE) emission, and self-trapped excitonic (STE) emission can also be achieved by adopting appropriate halogens and organic cations. Recently, significant efforts have been made to modulate and then clarify the transformation and connection between these two types of excitonic emissions in 2D HMHs. In this study, intriguing pressure-tuned transitions between FE emission and STE emission are observed in 2D (C H N ) PbCl .
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
December 2023
Center for Interdisciplinary Molecular Science, Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan.
Novel two-dimensional melamine lead iodide perovskite (2D-CHNPbI) is synthesized to investigate its crystallinity, optical band gap and broadband emission properties and to make comparisons with 2D-CHNPbCl/2D-CHNPbBr perovskites. Both experimental and density functional theory (DFT) interrogations on 2D-CHNPbX (X = Cl, Br and I) are conducted. The crystal structure, morphology and percentile of Pb and halide elements are confirmed using scanning electron microscope (SEM), and energy dispersive spectrum (EDS), powder/single crystal X-ray diffraction (PXRD/SXRD), DFT and X-ray crystallography simulations.
View Article and Find Full Text PDFJ Am Chem Soc
March 2023
Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Passivating defects using organic halide salts, especially chlorides, is an effective method to improve power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) arising from the stronger Pb-Cl bonding than Pb-I and Pb-Br bonding. However, Cl anions with a small radius are prone to incorporation into the perovskite lattice that distorts the lead halide octahedron, degrading the photovoltaic performance. Here, we substitute atomic-Cl-containing organic molecules for widely used ionic-Cl salts, which not only retain the efficient passivation by Cl but also prevent the incorporation of Cl into the bulk lattice, benefiting from the strong covalent bonding between Cl atoms and organic frameworks.
View Article and Find Full Text PDFInorg Chem
October 2022
Department of Experimental Physics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
Two-dimensional (2D) lead halide perovskites are a family of materials at the heart of solar cell, light-emitting diode, and photodetector technologies. This perspective leads to a number of synthetic efforts toward materials of this class, including those with prescribed polar architectures. The methylhydrazinium (MHy) cation was recently presumed to have an unusual capacity to generate non-centrosymmetric perovskite phases, despite its intrinsically nonchiral structure.
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