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Abfalterer A, Shamsi J, Kubicki DJ, Savory CN, Xiao J, Divitini G, Li W, Macpherson S, Gałkowski K, MacManus-Driscoll JL, Scanlon DO, Stranks SD. Colloidal Synthesis and Optical Properties of Perovskite-Inspired Cesium Zirconium Halide Nanocrystals. ACS MATERIALS LETTERS 2020; 2:1644-1652. [PMID: 33313512 PMCID: PMC7724740 DOI: 10.1021/acsmaterialslett.0c00393] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/27/2020] [Indexed: 06/01/2023]
Abstract
Optoelectronic devices based on lead halide perovskites are processed in facile ways, yet are remarkably efficient. There are extensive research efforts investigating lead-free perovskite and perovskite-related compounds, yet there are challenges to synthesize these materials in forms that can be directly integrated into thin film devices rather than as bulk powders. Here, we report on the colloidal synthesis and characterization of lead-free, antifluorite Cs2ZrX6 (X = Cl, Br) nanocrystals that are readily processed into thin films. We use transmission electron microscopy and powder X-ray diffraction measurements to determine their size and structural properties, and solid-state nuclear magnetic resonance measurements reveal the presence of oleate ligand, together with a disordered distribution of Cs surface sites. Density functional theory calculations reveal the band structure and fundamental band gaps of 5.06 and 3.91 eV for Cs2ZrCl6 and Cs2ZrBr6, respectively, consistent with experimental values. Finally, we demonstrate that the Cs2ZrCl6 and Cs2ZrBr6 nanocrystal thin films exhibit tunable, broad white photoluminescence with quantum yields of 45% for the latter, with respective peaks in the blue and green spectral regions and mixed systems exhibiting properties between them. Our work represents a critical step toward the application of lead-free Cs2ZrX6 nanocrystal thin films into next-generation light-emitting applications.
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Affiliation(s)
- Anna Abfalterer
- Cavendish Laboratory,
Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Javad Shamsi
- Cavendish Laboratory,
Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Dominik J. Kubicki
- Cavendish Laboratory,
Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Christopher N. Savory
- Department
of Chemistry and Thomas Young Centre, University
College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - James Xiao
- Cavendish Laboratory,
Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Giorgio Divitini
- Department
of Materials Science & Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Weiwei Li
- Department
of Materials Science & Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Stuart Macpherson
- Cavendish Laboratory,
Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Krzysztof Gałkowski
- Cavendish Laboratory,
Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Institute of Physics, Faculty of Physics,
Astronomy and Informatics, Nicolaus Copernicus
University, 5th Grudziądzka
St., 87-100 Toruń, Poland
| | - Judith L. MacManus-Driscoll
- Department
of Materials Science & Metallurgy, University
of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - David O. Scanlon
- Department
of Chemistry and Thomas Young Centre, University
College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- Diamond
Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Samuel D. Stranks
- Cavendish Laboratory,
Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Department of Chemical Engineering and
Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, United Kingdom
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Mandal S, Chandra M, Natarajan S. Synthesis, Structure, and Upconversion Studies on Organically Templated Uranium Phosphites. Inorg Chem 2007; 46:7935-43. [PMID: 17718481 DOI: 10.1021/ic700866f] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Three new amine templated uranium phosphites, [C2N2H10][U2IVF6(HPO3)2], 1, [C4N2H12][U2IVF6(HPO3)2], 2, and [C4N2H12][(UVIO2)2F2(HPO3)2], 3, have been synthesized by hydrothermal methods. All of the compounds are built up from a connectivity between U(O/F)x (x = 7, 8) and HPO3 polyhedral units. The observation of a well-established secondary building unit, SBU-4, in 1 and 2 is noteworthy. In 1, the SBU-4 units are connected to form U-F-U chains, which are linked by U-O-P chains, forming the layered structure. In 2, the SBU-4 units are edge-shared and also interconnected forming the 3D structure. In 3, the connectivity between the building units forms a layer, the topology of which is similar to the mineral, johannite. To the best of our knowledge, this is the first observation of a well-known secondary building unit (SBU-4) in actinide framework compounds. Optical studies on 1 and 2, containing U(4+) species, indicate an intense blue emission through an upconversion process, and the magnetic susceptibility studies show antiferromagnetic behavior.
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Affiliation(s)
- Sukhendu Mandal
- Framework Solids Laboratory, Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
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Ordejón B, Seijo L, Barandiarán Z. 5f→5f transitions of U4+ ions in high-field, octahedral fluoride coordination: The Cs2GeF6:U4+ crystal. J Chem Phys 2005; 123:204502. [PMID: 16351276 DOI: 10.1063/1.2121567] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The U-F bond length, totally symmetric vibrational frequency, and 5f(2) energy levels of the Cs(2)GeF(6):U(4+) crystal are predicted through quantum-chemical calculations on the embedded (UF(6))(2-) cluster. The U(4+) ions substitute for much smaller Ge(4+) retaining octahedral site symmetry, which is useful to interpret the electronic transitions. The structure of the 5f(2) manifold: its energy range, the crystal splitting of the 5f(2) levels, their parentage with free-ion levels, and the energy gaps appearing within the manifold, is presented and discussed, which allows to suggest which are the possible 5f(2) luminescent levels. The effects of Cl-to-F chemical substitution are discussed by comparison with isostructural Cs(2)ZrCl(6):U(4+). The energy range of the 5f(2) manifold increases by some 6000 cm(-1) and all levels shift to higher energies, but the shift is not uniform, so that noticeable changes of order are observed from Cs(2)ZrCl(6):U(4+) to Cs(2)GeF(6):U(4+). The comparison also reveals that the green-to-blue up-conversion luminescence, which has been experimentally detected and theoretically discussed on Cs(2)ZrCl(6):U(4+), is quenched in the fluoride host. The results of the Cs(2)GeF(6):U(4+) are used as a high-symmetry model to try to understand why efficient radiative cascade emissions in the visible do not occur for charged U(4+) defects in low-symmetry YF(3) crystals. The results presented here suggest that theoretical and experimental investigations of 4f5f ions doped in octahedral, high-symmetry fluoride crystals may be conducted even when the mismatch of ionic radii between the lanthanide/actinide ions and the substituted cations of the host is considerably large. Investigations of these new materials should reveal interesting spectroscopic features without the difficulties associated with more commonly used low-symmetry fluoride hosts.
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Affiliation(s)
- Belén Ordejón
- Departamento de Química, C-XIV, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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