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Zhao D, Flavell TA, Aljuaid F, Edmondson S, Spencer BF, Walton AS, Thomas AG, Flavell WR. Elucidating the Mechanism of Self-Healing in Hydrogel-Lead Halide Perovskite Composites for Use in Photovoltaic Devices. ACS Appl Mater Interfaces 2023. [PMID: 37253100 DOI: 10.1021/acsami.3c03359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Since the emergence of organometal halide perovskite (OMP) solar cells, there has been growing interest in the benefits of incorporating polymer additives into the perovskite precursor, in terms of both photovoltaic device performance and perovskite stability. In addition, there is interest in the self-healing properties of polymer-incorporated OMPs, but the mechanisms behind these enhanced characteristics are still not fully understood. Here, we study the role of poly(2-hydroxyethyl methacrylate) (pHEMA) in improving the stability of methylammonium lead iodide (MAPI, CH3NH3PbI3) and determine a mechanism for the self-healing of the perovskite-polymer composite following exposure to atmospheres of differing relative humidity, using photoelectron spectroscopy. Varying concentrations of pHEMA (0-10 wt %) are incorporated into a PbI2 precursor solution during the conventional two-step fabrication method for producing MAPI. It is shown that the introduction of pHEMA results in high-quality MAPI films with increased grain size and reduced PbI2 concentration compared with pure MAPI films. Devices based on pHEMA-MAPI composites exhibit an improved photoelectric conversion efficiency of 17.8%, compared with 16.5% for a pure MAPI device. pHEMA-incorporated devices are found to retain 95.4% of the best efficiency after ageing for 1500 h in 35% RH, compared with 68.5% achieved from the pure MAPI device. The thermal and moisture tolerance of the resulting films is investigated using X-ray diffraction, in situ X-ray photoelectron spectroscopy (XPS), and hard XPS (HAXPES). It is found that exposing the pHEMA films to cycles of 70 and 20% relative humidity leads to a reversible degradation, via a self-healing process. Angle-resolved HAXPES depth-profiling using a non-destructive Ga Kα source shows that pHEMA is predominantly present at the surface with an effective thickness of ca. 3 nm. It is shown using XPS that this effective thickness reduces with increasing temperature. It is found that N is trapped in this surface layer of pHEMA, suggesting that N-containing moieties, produced during reaction with water at high humidity, are trapped in the pHEMA film and can be reincorporated into the perovskite when the humidity is reduced. XPS results also show that the inclusion of pHEMA enhances the thermal stability of MAPI under both UHV and 9 mbar water vapor pressure.
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Affiliation(s)
- Dawei Zhao
- Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Tom A Flavell
- Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Fahad Aljuaid
- Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Stephen Edmondson
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Ben F Spencer
- Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Henry Royce Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Alex S Walton
- Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Andrew G Thomas
- Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Henry Royce Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Wendy R Flavell
- Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
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Burkitt-Gray M, Casavola M, Clark PCJ, Fairclough SM, Flavell WR, Fleck RA, Haigh SJ, Ke JCR, Leontiadou M, Lewis EA, Osiecki J, Qazi-Chaudhry B, Vizcay-Barrena G, Wichiansee W, Green M. Structural investigations into colour-tuneable fluorescent InZnP-based quantum dots from zinc carboxylate and aminophosphine precursors. Nanoscale 2023; 15:1763-1774. [PMID: 36601869 DOI: 10.1039/d2nr02803d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Fluorescent InP-based quantum dots have emerged as valuable nanomaterials for display technologies, biological imaging, and optoelectronic applications. The inclusion of zinc can enhance both their emissive and structural properties and reduce interfacial defects with ZnS or CdS shells. However, the sub-particle distribution of zinc and the role this element plays often remains unclear, and it has previously proved challenging to synthesise Zn-alloyed InP-based nanoparticles using aminophosphine precursors. In this report, we describe the synthesis of alloyed InZnP using zinc carboxylates, achieving colour-tuneable fluorescence from the unshelled core materials, followed by a one-pot ZnS or CdS deposition using diethyldithiocarbamate precursors. Structural analysis revealed that the "core/shell" particles synthesised here were more accurately described as homogeneous extended alloys with the constituent shell elements diffusing through the entire core, including full-depth inclusion of zinc.
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Affiliation(s)
- Mary Burkitt-Gray
- Department of Physics, King's College London, The Strand, London, WC2R 2LS, UK.
- Centre for Ultrastructural Imaging, King's College London, New Hunt's House, London, SE1 1UL, UK
| | - Marianna Casavola
- Department of Physics, King's College London, The Strand, London, WC2R 2LS, UK.
| | - Pip C J Clark
- The Photon Science Institute, School of Physics and Astronomy, University of Manchester, Schuster Building, Oxford Road, Manchester, M13 9PL, UK
| | - Simon M Fairclough
- Department of Physics, King's College London, The Strand, London, WC2R 2LS, UK.
| | - Wendy R Flavell
- The Photon Science Institute, School of Physics and Astronomy, University of Manchester, Schuster Building, Oxford Road, Manchester, M13 9PL, UK
| | - Roland A Fleck
- Centre for Ultrastructural Imaging, King's College London, New Hunt's House, London, SE1 1UL, UK
| | - Sarah J Haigh
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Jack Chun-Ren Ke
- The Photon Science Institute, School of Physics and Astronomy, University of Manchester, Schuster Building, Oxford Road, Manchester, M13 9PL, UK
| | - Marina Leontiadou
- The Photon Science Institute, School of Physics and Astronomy, University of Manchester, Schuster Building, Oxford Road, Manchester, M13 9PL, UK
| | - Edward A Lewis
- Department of Materials, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Jacek Osiecki
- MAX IV Laboratory, Lund University, Box 118, 221 00 Lund, Sweden
| | - Basma Qazi-Chaudhry
- Department of Physics, King's College London, The Strand, London, WC2R 2LS, UK.
| | - Gema Vizcay-Barrena
- Centre for Ultrastructural Imaging, King's College London, New Hunt's House, London, SE1 1UL, UK
| | - Wijittra Wichiansee
- Department of Physics, King's College London, The Strand, London, WC2R 2LS, UK.
| | - Mark Green
- Department of Physics, King's College London, The Strand, London, WC2R 2LS, UK.
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Arrigo R, Aureau D, Bhatt P, Buckingham MA, Counter JJC, D'Acunto G, Davies PR, Evans DA, Flavell WR, Gibson JS, Guan S, Held G, Isaacs M, Kahk JM, Kastorp CFP, Kersell H, Krizan A, Large AI, Lindsay R, Lischner J, Lömker P, Morgan D, Nemšák S, Nilsson A, Payne D, Reed BP, Renault O, Rupprechter G, Shard AG, Shozi M, Silly MG, Skinner WSJ, Solal F, Stoerzinger KA, Suzer S, Velasco Vélez JJ, Walker M, Weatherup RS. In situ methods: discoveries and challenges: general discussion. Faraday Discuss 2022; 236:219-266. [PMID: 35968885 DOI: 10.1039/d2fd90025d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Cant DJH, Spencer BF, Flavell WR, Shard AG. Erratum: Correction to “Quantification of hard X‐ray photoelectron spectroscopy: Calculating relative sensitivity factors for 1.5‐ to 10‐keV photons in any instrument geometry”. SURF INTERFACE ANAL 2022. [DOI: 10.1002/sia.7124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | - Ben F. Spencer
- Henry Royce Institute and the Department of Materials, School of Natural Sciences The University of Manchester Manchester UK
| | - Wendy R. Flavell
- Henry Royce Institute, Photon Science Institute, and Department of Physics and Astronomy, School of Natural Sciences The University of Manchester Manchester UK
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Cant DJH, Spencer BF, Flavell WR, Shard AG. Quantification of hard X‐ray photoelectron spectroscopy: Calculating relative sensitivity factors for 1.5‐ to 10‐keV photons in any instrument geometry. SURF INTERFACE ANAL 2022. [DOI: 10.1002/sia.7059] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
| | - Ben F. Spencer
- Henry Royce Institute and the Department of Materials, School of Natural Sciences The University of Manchester Manchester UK
| | - Wendy R. Flavell
- Henry Royce Institute, Photon Science Institute, and Department of Physics and Astronomy, School of Natural Sciences The University of Manchester Manchester UK
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6
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Clark PCJ, Lewis NK, Ke JCR, Ahumada-Lazo R, Chen Q, Neo DCJ, Gaulding EA, Pach GF, Pis I, Silly MG, Flavell WR. Surface band bending and carrier dynamics in colloidal quantum dot solids. Nanoscale 2021; 13:17793-17806. [PMID: 34668501 DOI: 10.1039/d1nr05436h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Band bending in colloidal quantum dot (CQD) solids has become important in driving charge carriers through devices. This is typically a result of band alignments at junctions in the device. Whether band bending is intrinsic to CQD solids, i.e. is band bending present at the surface-vacuum interface, has previously been unanswered. Here we use photoemission surface photovoltage measurements to show that depletion regions are present at the surface of n and p-type CQD solids with various ligand treatments (EDT, MPA, PbI2, MAI/PbI2). Using laser-pump photoemission-probe time-resolved measurements, we show that the timescale of carrier dynamics in the surface of CQD solids can vary over at least 6 orders of magnitude, with the fastest dynamics on the order of microseconds in PbS-MAI/PbI2 solids and on the order of seconds for PbS-MPA and PbS-PbI2. By investigating the surface chemistry of the solids, we find a correlation between the carrier dynamics timescales and the presence of oxygen contaminants, which we suggest are responsible for the slower dynamics due to deep trap formation.
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Affiliation(s)
- Pip C J Clark
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK.
| | - Nathan K Lewis
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK.
| | - Jack Chun-Ren Ke
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK.
| | - Ruben Ahumada-Lazo
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK.
| | - Qian Chen
- Department of Materials, The University of Manchester, Manchester M13 9PL, UK
| | - Darren C J Neo
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, USA
| | | | - Gregory F Pach
- National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Igor Pis
- Laboratorio TASC, IOM CNR, S.S. 14 km 163.5, 34149 Basovizza, Trieste, Italy
- Elettra-Sincrotrone Trieste S.C.p.A., S. S. 14 Km 163.5, 34149 Basovizza, Trieste, Italy
| | - Mathieu G Silly
- Synchrotron SOLEIL, BP 48, Saint-Aubin, F91192 Gif sur Yvette CEDEX, France
| | - Wendy R Flavell
- Department of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK.
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7
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Maniyarasu S, Ke JCR, Spencer BF, Walton AS, Thomas AG, Flavell WR. Role of Alkali Cations in Stabilizing Mixed-Cation Perovskites to Thermal Stress and Moisture Conditions. ACS Appl Mater Interfaces 2021; 13:43573-43586. [PMID: 34463487 DOI: 10.1021/acsami.1c10420] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Perovskite solar cells (PSCs) based on organic-inorganic hybrid perovskites containing a small fraction of substituted alkali-metal cations have shown remarkable performance and stability. However, the role of these cations is unclear. The thermal- and moisture-induced degradation of FA1-xCsxPbI3 and (FA1-xCsx)1-yRbyPbI3 (where FA represents formamidinium, x, y = 0.1, 0.05) is investigated using in situ photoelectron spectroscopy (PES). Both compositions exhibit superior moisture stability compared with methylammonium lead iodide under 9 mbar of water vapor. Ga Kα hard X-ray PES is used to investigate the composition of the perovskites at depths up to 45 nm into the surface. This allows more accurate quantification of the alkali-metal distribution than is possible using conventional X-ray PES. The addition of RbI results in a fairly homogeneous distribution of both Cs+ and Rb+ in the surface layers (in contrast to surface Cs depletion seen in its absence), together with a marked reduction in surface iodide vacancies. Overall, RbI is found to play a critical role in increasing the thermal stability of FA1-xCsxPbI3 by providing a source of I- that fills iodine vacancy sites in the perovskite lattice, while Rb+ is not substantially incorporated into the perovskite. We suggest that the concomitant increase in ion migration barriers in the surface layers is key to improved PSC performance and long-lasting stability.
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Affiliation(s)
- Suresh Maniyarasu
- Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - J Chun-Ren Ke
- Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Ben F Spencer
- Department of Materials, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Henry Royce Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Alex S Walton
- Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Department of Chemistry, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Andrew G Thomas
- Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Department of Materials, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Henry Royce Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Wendy R Flavell
- Department of Physics and Astronomy, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
- Henry Royce Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
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8
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Clark PCJ, Flavell WR. Surface and Interface Chemistry in Colloidal Quantum Dots for Solar Applications Studied by X-Ray Photoelectron Spectroscopy. CHEM REC 2018; 19:1233-1243. [PMID: 30387544 DOI: 10.1002/tcr.201800085] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 10/12/2018] [Indexed: 11/10/2022]
Abstract
Control of the surface and interface chemistry of colloidal quantum dots (CQDs) is critical to achieving a product with good air stability and high performing optoelectronic devices. Through various surface passivation treatments, vast improvements have been made in fields such as CQD photovoltaics; however devices have not currently reached commercial standards. We show how X-ray photoelectron spectroscopy (XPS) can provide a better understanding of exactly how surface treatments act on CQD surfaces, and the effect of surface composition on air stability and device performance.. We illustrate this with PbS-based CQDs, using XPS to measure oxidation processes, and to quantify the composition of the topmost surface layer after different surface treatments. We also demonstrate the use of synchrotron radiation-excited depth-profiling XPS, a powerful technique for determining the surface composition, chemistry and structure of CQDs. This review describes our recent progress in characterization of CQD surfaces using SR-excited depth profiling XPS and other photoemission techniques.
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Affiliation(s)
- Pip C J Clark
- School of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester, M13 9PL, UK.,Present address: Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner Platz 1, D-14109 Berlin, Germany
| | - Wendy R Flavell
- School of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester, M13 9PL, UK
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9
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Clark PCJ, Neo DCJ, Ahumada-Lazo R, Williamson AI, Pis I, Nappini S, Watt AAR, Flavell WR. Influence of Multistep Surface Passivation on the Performance of PbS Colloidal Quantum Dot Solar Cells. Langmuir 2018; 34:8887-8897. [PMID: 29975548 DOI: 10.1021/acs.langmuir.8b01453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The performance of devices containing colloidal quantum dot (CQD) films is strongly dependent on the surface chemistry of the CQDs they contain. Multistep surface treatments, which combine two or more strategies, are important for creating films with high carrier mobility that are well passivated against trap states and oxidation. Here, we examine the effect of a number of these surface treatments on PbS CQD films, including cation exchange to form PbS/CdS core/shell CQDs, and solid-state ligand-exchange treatments with Cl, Br, I, and 1,2-ethanedithiol (EDT) ligands. Using laboratory-based and synchrotron-radiation-excited X-ray photoelectron spectroscopy (XPS), we examine the compositions of the surface layer before and after treatment, and correlate this with the performance data and stability in air. We find that halide ion treatments may etch the CQD surfaces, with detrimental effects on the air stability and solar cell device performance caused by a reduction in the proportion of passivated surface sites. We show that films made up of PbS/CdS CQDs are particularly prone to this, suggesting Cd is more easily etched from the surface than Pb. However, by choosing a less aggressive ligand treatment, a good coverage of passivators on the surface can be achieved. We show that halide anions bind preferentially to surface Pb (rather than Cd). By isolating the part of XPS signal originating from the topmost surface layer of the CQD, we show that air stability is correlated with the total number of passivating agents (halide + EDT + Cd) at the surface.
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Affiliation(s)
- Pip C J Clark
- School of Physics and Astronomy and the Photon Science Institute , The University of Manchester , Manchester M13 9PL , United Kingdom
| | - Darren C J Neo
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
| | - Ruben Ahumada-Lazo
- School of Physics and Astronomy and the Photon Science Institute , The University of Manchester , Manchester M13 9PL , United Kingdom
| | - Andrew I Williamson
- School of Physics and Astronomy and the Photon Science Institute , The University of Manchester , Manchester M13 9PL , United Kingdom
| | - Igor Pis
- Elettra-Sincrotrone Trieste S.C.p.A. , S. S. 14 km 163.5 , Basovizza 34149 , Trieste , Italy
| | - Silvia Nappini
- Laboratorio TASC, IOM CNR , S. S. 14 km 163.5 , Basovizza 34149 , Trieste , Italy
| | - Andrew A R Watt
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
| | - Wendy R Flavell
- School of Physics and Astronomy and the Photon Science Institute , The University of Manchester , Manchester M13 9PL , United Kingdom
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Clark PCJ, Radtke H, Pengpad A, Williamson AI, Spencer BF, Hardman SJO, Leontiadou MA, Neo DCJ, Fairclough SM, Watt AAR, Pis I, Nappini S, Bondino F, Magnano E, Handrup K, Schulte K, Silly MG, Sirotti F, Flavell WR. The passivating effect of cadmium in PbS/CdS colloidal quantum dots probed by nm-scale depth profiling. Nanoscale 2017; 9:6056-6067. [PMID: 28443889 DOI: 10.1039/c7nr00672a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Achieving control of the surface chemistry of colloidal quantum dots (CQDs) is essential to fully exploit their properties in solar cells, but direct measurement of the chemistry and electronic structure in the outermost atomic layers is challenging. Here we probe the surface oxidation and passivation of cation-exchanged PbS/CdS core/shell CQDs with sub nm-scale precision using synchrotron-radiation-excited depth-profiling photoemission. We investigate the surface composition of the topmost 1-2.5 nm of the CQDs as a function of depth, for CQDs of varying CdS shell thickness, and examine how the surface changes after prolonged air exposure. We demonstrate that the Cd is localized at the surface of the CQDs. The surface-localized products of oxidation are identified, and the extent of oxidation quantified. We show that oxidised sulfur species are progressively eliminated as Cd replaces Pb at the surface. A sub-monolayer surface 'decoration' of Cd is found to be effective in passivating the CQDs. We show that the measured energy-level alignments at PbS/CdS colloidal quantum dot surfaces differ from those expected on the basis of bulk band offsets, and are strongly affected by the oxidation products. We develop a model for the passivating action of Cd. The optimum shell thickness (of around 0.1 nm, previously found to give maximised power conversion efficiency in PbS/CdS solar cells) is found to correspond to a trade-off between the rate of oxidation and the introduction of a surface barrier to charge transport.
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Affiliation(s)
- Pip C J Clark
- School of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK.
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11
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Chun-Ren Ke J, Walton AS, Lewis DJ, Tedstone A, O'Brien P, Thomas AG, Flavell WR. In situ investigation of degradation at organometal halide perovskite surfaces by X-ray photoelectron spectroscopy at realistic water vapour pressure. Chem Commun (Camb) 2017; 53:5231-5234. [DOI: 10.1039/c7cc01538k] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Near-ambient-pressure X-ray photoelectron spectroscopy enables the study of the reaction of in situ-prepared methylammonium lead iodide (MAPI) perovskite at realistic water vapour pressures for the first time.
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Affiliation(s)
- Jack Chun-Ren Ke
- School of Physics and Astronomy
- The University of Manchester
- Oxford Road
- Manchester
- UK
| | - Alex S. Walton
- Photon Science Institute
- The University of Manchester
- Oxford Road
- Manchester
- UK
| | - David J. Lewis
- School of Materials
- The University of Manchester
- Oxford Road
- Manchester
- UK
| | | | - Paul O'Brien
- School of Chemistry
- The University of Manchester
- Oxford Road
- Manchester
- UK
| | - Andrew G. Thomas
- Photon Science Institute
- The University of Manchester
- Oxford Road
- Manchester
- UK
| | - Wendy R. Flavell
- School of Physics and Astronomy
- The University of Manchester
- Oxford Road
- Manchester
- UK
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12
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Page RC, Espinobarro-Velazquez D, Leontiadou MA, Smith C, Lewis EA, Haigh SJ, Li C, Radtke H, Pengpad A, Bondino F, Magnano E, Pis I, Flavell WR, O'Brien P, Binks DJ. Near-unity quantum yields from chloride treated CdTe colloidal quantum dots. Small 2015; 11:1548-54. [PMID: 25348200 PMCID: PMC4409856 DOI: 10.1002/smll.201402264] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 09/14/2014] [Indexed: 05/19/2023]
Abstract
Colloidal quantum dots (CQDs) are promising materials for novel light sources and solar energy conversion. However, trap states associated with the CQD surface can produce non-radiative charge recombination that significantly reduces device performance. Here a facile post-synthetic treatment of CdTe CQDs is demonstrated that uses chloride ions to achieve near-complete suppression of surface trapping, resulting in an increase of photoluminescence (PL) quantum yield (QY) from ca. 5% to up to 97.2 ± 2.5%. The effect of the treatment is characterised by absorption and PL spectroscopy, PL decay, scanning transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. This process also dramatically improves the air-stability of the CQDs: before treatment the PL is largely quenched after 1 hour of air-exposure, whilst the treated samples showed a PL QY of nearly 50% after more than 12 hours.
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Affiliation(s)
- Robert C Page
- FRS, School of Chemistry, University of ManchesterManchester, M13 9PL, UK
| | | | - Marina A Leontiadou
- School of Physics and Astronomy and Photon Science Institute, University of ManchesterManchester, M13 9PL, UK
| | - Charles Smith
- School of Physics and Astronomy and Photon Science Institute, University of ManchesterManchester, M13 9PL, UK
| | - Edward A Lewis
- School of Materials, University of ManchesterManchester, M13 9PL, UK
| | - Sarah J Haigh
- School of Materials, University of ManchesterManchester, M13 9PL, UK
| | - Chen Li
- Department of Chemistry, Vanderbilt University NashvilleTN, 37235 USA and Oak Ridge National Laboratory 1 Bethel Valley Road, Oak Ridge, TN, 37831–6071, USA
| | - Hanna Radtke
- School of Physics and Astronomy and Photon Science Institute, University of ManchesterManchester, M13 9PL, UK
| | - Atip Pengpad
- School of Physics and Astronomy and Photon Science Institute, University of ManchesterManchester, M13 9PL, UK
| | - Federica Bondino
- IOM CNR, Laboratorio Nazionale TASC, Area Science Park – BasovizzaS.S. 14 Km. 163, 5 I-34149, Basovizza, (TS), Italy
| | - Elena Magnano
- IOM CNR, Laboratorio Nazionale TASC, Area Science Park – BasovizzaS.S. 14 Km. 163, 5 I-34149, Basovizza, (TS), Italy
| | - Igor Pis
- IOM CNR, Laboratorio Nazionale TASC, Area Science Park – BasovizzaS.S. 14 Km. 163, 5 I-34149, Basovizza, (TS), Italy
| | - Wendy R Flavell
- School of Physics and Astronomy and Photon Science Institute, University of ManchesterManchester, M13 9PL, UK
| | - Paul O'Brien
- FRS, School of Chemistry, University of ManchesterManchester, M13 9PL, UK
| | - David J Binks
- School of Physics and Astronomy and Photon Science Institute, University of ManchesterManchester, M13 9PL, UK
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Cant DJH, Syres KL, Lunt PJB, Radtke H, Treacy J, Thomas PJ, Lewis EA, Haigh SJ, O'Brien P, Schulte K, Bondino F, Magnano E, Flavell WR. Surface properties of nanocrystalline PbS films deposited at the water-oil interface: a study of atmospheric aging. Langmuir 2015; 31:1445-53. [PMID: 25557338 DOI: 10.1021/la504779h] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Nanocrystalline thin films of PbS are obtained in a straightforward reaction by precipitation at the interface between toluene (containing a Pb precursor) and water (containing Na2S). Lead thiobiuret [Pb(SON(CN(i)Pr2)2)2] and lead diethyldithiocarbamate [Pb(S2CNEt2)2] precursors are used. The films are characterized by X-ray diffraction and electron microscopy, revealing typical particle sizes of 10-40 nm and preferred (200) orientation. Synchrotron-excited depth-profiling X-ray photoelectron spectroscopy (XPS) is used to determine the depth-dependent chemical composition as a function of surface aging in air for periods of up to 9 months. The as-synthesized films show a 1:1 Pb/S composition. Initial degradation occurs to form lead hydroxide and small quantities of surface-adsorbed -SH species. A lead-deficient Pb1-xS phase is produced as the aging proceeds. Oxidation of the sulfur occurs later to form sulfite and sulfate products that are highly localized at the surface layers of the nanocrystals. These species show logarithmic growth kinetics, demonstrating that the sulfite/sulfate layer acts to passivate the nanocrystals. Our results demonstrate that the initial reaction of the PbS nanocrystals (forming lead hydroxide) is incongruent. The results are discussed in the context of the use of PbS nanocrystals as light-harvesting elements in next-generation solar technology.
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Affiliation(s)
- David J H Cant
- School of Physics and Astronomy and the Photon Science Institute, and ‡School of Materials, The University of Manchester , Manchester M13 9PL, United Kingdom
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Thomas PJ, Stansfield GL, Komba N, Cant DJH, Ramasamy K, Albrasi E, Al-Chaghouri H, Syres KL, O'Brien P, Flavell WR, Mubofu E, Bondino F, Magnano E. Growth of nanocrystalline thin films of metal sulfides [CdS, ZnS, CuS and PbS] at the water–oil interface. RSC Adv 2015. [DOI: 10.1039/c5ra09417h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Films of Nanocrystalline CuS, PbS, CdS and ZnS at water toluene interface.
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Affiliation(s)
| | | | - Nathanael Komba
- School of Chemistry
- The University of Manchester
- Manchester M139PL
- UK
| | - David J. H. Cant
- School of Chemistry
- The University of Manchester
- Manchester M139PL
- UK
| | - Karthik Ramasamy
- School of Chemistry
- The University of Manchester
- Manchester M139PL
- UK
| | - Enteisar Albrasi
- School of Chemistry
- The University of Manchester
- Manchester M139PL
- UK
| | | | - Karen L. Syres
- School of Chemistry
- The University of Nottingham
- University Park
- Nottingham NG7 2RD
- UK
| | - Paul O'Brien
- School of Chemistry
- The University of Manchester
- Manchester M139PL
- UK
- School of Materials
| | - Wendy R. Flavell
- Photon Science Institute
- School of Physics and Astronomy
- The University of Manchester
- Manchester M13 9PL
- UK
| | - Egid Mubofu
- Department of Chemistry
- University of Dar es Salaam
- Dar es Salaam
- Tanzania
| | | | - Elena Magnano
- IOM CNR
- Laboratorio Nazionale TASC
- I-34149 Basovizza
- Italy
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Spencer BF, Cliffe MJ, Graham DM, Hardman SJO, Seddon EA, Syres KL, Thomas AG, Sirotti F, Silly MG, Akhtar J, O'Brien P, Fairclough SM, Smith JM, Chattopadhyay S, Flavell WR. Dynamics in next-generation solar cells: time-resolved surface photovoltage measurements of quantum dots chemically linked to ZnO (101̄0). Faraday Discuss 2014; 171:275-98. [DOI: 10.1039/c4fd00019f] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The charge dynamics at the surface of the transparent conducting oxide and photoanode material ZnO are investigated in the presence and absence of light-harvesting colloidal quantum dots (QDs). The time-resolved change in surface potential upon photoexcitation has been measured in the m-plane ZnO (101̄0) using a laser pump-synchrotron X-ray probe methodology. By varying the oxygen annealing conditions, and hence the oxygen vacancy concentration of the sample, we find that dark carrier lifetimes at the ZnO surface vary from hundreds of μs to ms timescales, i.e. a persistent photoconductivity (PPC) is observed. The highly-controlled nature of our experiments under ultra-high vacuum (UHV), and the use of band-gap and sub-band-gap photoexcitation, allow us to demonstrate that defect states ca. 340 meV above the valence band edge are directly associated with the PPC, and that the PPC mediated by these defects dominates over the oxygen photodesorption mechanism. These observations are consistent with the hypothesis that ionized oxygen vacancy states are responsible for the PPC in ZnO. The effect of chemically linking two colloidal QD systems (type I PbS and type II CdS–ZnSe) to the surface has also been investigated. Upon deposition of the QDs onto the surface, the dark carrier lifetime and the surface photovoltage are reduced, suggesting a direct injection of charge carriers into the ZnO conduction band. The results are discussed in the context of the development of next-generation solar cells.
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Affiliation(s)
- Ben F. Spencer
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
- The Cockcroft Institute
- Sci-Tech Daresbury, Keckwick Lane, Daresbury
| | - Matthew J. Cliffe
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
- The Cockcroft Institute
- Sci-Tech Daresbury, Keckwick Lane, Daresbury
| | - Darren M. Graham
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
| | - Samantha J. O. Hardman
- Manchester Institute of Biotechnology
- Faculty of Life Sciences
- University of Manchester
- Manchester M1 7DN, United Kingdom
| | - Elaine A. Seddon
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
- The Cockcroft Institute
- Sci-Tech Daresbury, Keckwick Lane, Daresbury
| | - Karen L. Syres
- School of Chemistry
- The University of Nottingham
- Nottingham NG7 2RD, United Kingdom
| | - Andrew G. Thomas
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
| | | | | | - Javeed Akhtar
- Department of Chemistry
- University of Manchester
- Manchester M13 9PL, United Kingdom
- Department of Physics
- Nano-Science & Materials Synthesis Laboratory
| | - Paul O'Brien
- Department of Chemistry
- University of Manchester
- Manchester M13 9PL, United Kingdom
| | | | - Jason M. Smith
- Department of Materials
- University of Oxford
- Oxford OX1 3PH, United Kingdom
| | - Swapan Chattopadhyay
- The Cockcroft Institute
- Sci-Tech Daresbury, Keckwick Lane, Daresbury
- Warrington WA4 4AD, United Kingdom
| | - Wendy R. Flavell
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
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Akhtar J, Afzaal M, Banski M, Podhorodecki A, Syperek M, Misiewicz J, Bangert U, Hardman SJO, Graham DM, Flavell WR, Binks DJ, Gardonio S, O’Brien P. Controlled Synthesis of Tuned Bandgap Nanodimensional Alloys of PbSxSe1−x. J Am Chem Soc 2011; 133:5602-9. [DOI: 10.1021/ja200750s] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Javeed Akhtar
- School of Chemistry and Materials Science Centre, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Mohammad Afzaal
- Center of Research Excellence in Renewable Energy, King Fahd University of Petroleum and Minerals, Dhahran, 31261 Saudi Arabia
| | - Mateusz Banski
- Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Artur Podhorodecki
- Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Marcin Syperek
- Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Jan Misiewicz
- Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Ursel Bangert
- Materials Science Centre, The University of Manchester, Grosvenor Street, Manchester M1 7HS, United Kingdom
| | - Samantha J. O. Hardman
- School of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Darren M. Graham
- School of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Wendy R. Flavell
- School of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - David J. Binks
- School of Physics and Astronomy and the Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Sandra Gardonio
- SuperESCA beamline, Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34012 Basovizza, Trieste, Italy
| | - Paul O’Brien
- School of Chemistry and Materials Science Centre, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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Hardman SJO, Graham DM, Stubbs SK, Spencer BF, Seddon EA, Fung HT, Gardonio S, Sirotti F, Silly MG, Akhtar J, O'Brien P, Binks DJ, Flavell WR. Electronic and surface properties of PbS nanoparticles exhibiting efficient multiple exciton generation. Phys Chem Chem Phys 2011; 13:20275-83. [DOI: 10.1039/c1cp22330e] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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18
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Akhtar J, Azad Malik M, O'Brien P, Wijayantha KGU, Dharmadasa R, Hardman SJO, Graham DM, Spencer BF, Stubbs SK, Flavell WR, Binks DJ, Sirotti F, El Kazzi M, Silly M. A greener route to photoelectrochemically active PbS nanoparticles. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/b924436k] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kumarasinghe AR, Flavell WR, Thomas AG, Mallick AK, Tsoutsou D, Chatwin C, Rayner S, Kirkham P, Warren S, Patel S, Christian P, O'Brien P, Grätzel M, Hengerer R. Electronic properties of the interface between p-CuI and anatase-phase n-TiO2 single crystal and nanoparticulate surfaces: A photoemission study. J Chem Phys 2007; 127:114703. [PMID: 17887866 DOI: 10.1063/1.2772249] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a study of the growth of the p-type inorganic semiconductor CuI on n-type TiO2 anatase single crystal (101) surfaces and on nanoparticulate anatase surfaces using synchrotron radiation photoemission spectroscopy. Core level photoemission data obtained using synchrotron radiation reveal that both the substrate (TiO2) and the overlayer (CuI) core levels shift to a lower binding energy to different degrees following the growth of CuI on TiO2. Valence band photoemission data show that the valence band maximum of the clean substrate differs from that of the dosed surface which may be interpreted qualitatively as due to the introduction of a new density of states within the band gap of TiO2 as a result of the growth of CuI. The valence band offset for the heterojunction n-TiO2p-CuI has been measured using photoemission for both nanoparticulate and single crystal TiO2 surfaces, and the band energy alignment for these heterojunction interfaces is presented. With the information obtained here, it is suggested that the interface between p-CuI and single crystal anatase-phase n-TiO2 is a type-II heterojunction interface, with significant band bending. The measured total band bending matches the work function change at the interface, i.e., there is no interface dipole. In the case of the nanoparticulate interface, an interface dipole is found, but band bending within the anatase nanoparticles remains quite significant. We show that the corresponding depletion layer may be accommodated within the dimension of the nanoparticles. The results are discussed in the context of the functional properties of dye-sensitized solid state solar cells.
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Affiliation(s)
- A R Kumarasinghe
- School of Physics and Astronomy, The University of Manchester, Sackville Street Building, P.O. Box 88, Manchester M60 1QD, United Kingdom
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Affiliation(s)
- Robert I. Hines
- a School of Chemistry, University of Bristol , Cantocks Close, Bristol , BS8 ITS , England
| | - Neil L. Allan
- a School of Chemistry, University of Bristol , Cantocks Close, Bristol , BS8 ITS , England
| | - Wendy R. Flavell
- b Department of Chemistry , University of Manchester, Institute of Science and Technology , PO Box 88, Manchester , M60 1QD , England
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Flavell WR, Nicholson DG, Nilsen MH, Ståhl K. X-Ray powder diffraction and EXAFS studies on SnAPO-5 and Cu∶SnAPO-5. ACTA ACUST UNITED AC 2001. [DOI: 10.1039/b005321j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Flavell WR, Thomas AG, Hollingworth J, Warren S, Grice SC, Dunwoody PM, Mitchell CEJ, Marr PGD, Teehan D, Downes S, Seddon EA, Dhanak VR, Asai K, Koboyashi Y, Yamada N. Electronic structure and surface reactivity of La1-xSrxCoO3. Faraday Discuss 1999. [DOI: 10.1039/a902409c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Hancock FE, King F, Flavell WR, Islam M. Catalytically enhanced absorption of sulphur species from odorous air streams: A new technology for odour abatement. Catal Today 1998. [DOI: 10.1016/s0920-5861(98)00058-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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24
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Hines RI, Allan NL, Flavell WR. Oxidation catalysts: a comparative simulation study of the lattice, defect and surface structure of the stannates ASnO3(A = Ca, Sr and Ba) and SnO2. ACTA ACUST UNITED AC 1996. [DOI: 10.1039/ft9969202057] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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25
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Howlett JF, Flavell WR, Thomas AG, Hollingworth J, Warren S, Hashim Z, Mian M, Squire S, Aghabozorg HR, Sarker MM, Wincott PL, Teehan D, Downes S, Law DSL, Hancock FE. Electronic structure, reactivity and solid-state chemistry of La2 –xSrxNi1 –yFeyO4 +δ. Faraday Discuss 1996. [DOI: 10.1039/fd9960500337] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Flavell WR, Hollingworth J, Howlett JF, Thomas AG, Sarker MM, Squire S, Hashim Z, Mian M, Wincott PL, Teehan D, Downes S, Hancock FE. Resonant photoemission from complex cuprates and nickelates. J Synchrotron Radiat 1995; 2:264-71. [PMID: 16714827 DOI: 10.1107/s0909049595008156] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Synchrotron-excited resonant-photoemission measurements at rare-earth 4d --> 4f and transition-metal 3p --> 3d thresholds have been carried out using a variety of complex cuprates and nickelates on stations 6.1 (grazing-incidence monochromator) and 6.2 (toroidal-grating monochromator) at the SRS CLRC Daresbury Laboratory. The systems studied are Nd(2)Ni(1 - x)Cu(x)O(4), La(2 - x)Sr(x)Ni(1- y)Fe(y)O(4 + delta) and Bi(2)Sr(2)Ca(1 - x)Y(x)Cu(2)O(8 + delta). A combination of EDC and constant-initial-state data is used to examine the 4f and 3d contributions to the valence-band density of states and their binding-energy positions relative to the Fermi energy. This allows the study of the valence states of the transition-metal ions and their modulation on doping. For La(2 - x)Sr(x)Ni(1 - y)Fe(y)O(4 + delta), this approach is used to infer a valence state of >/= 3.0 for Fe. In the case of Bi(2)Sr(2)Ca(1 - x)Y(x)Cu(2)O(8 + delta), the effect of Cu valence modulation on the 3p resonance is observed as x is varied. This is discussed in the light of controversy surrounding shifts in core-level photoemission with doping for this system.
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Mian M, Flavell WR. The k-space components of a photoelectron from an arbitrarily oriented crystal face. J Synchrotron Radiat 1995; 2:201-2. [PMID: 16714816 DOI: 10.1107/s0909049595006182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
A standard rotational matrix method is described for determining the k-space components of photoelectrons emitted from a crystal surface, which is arbitrarily oriented with respect to the experimental frame. This simplifies the analysis of angle-resolved photoemission data from a crystal surface not aligned to the experimental chamber axes.
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Flavell WR, Mian M, Morris BC, Wincott PL, Teehan D, Law DS. Angle-resolved-photoemission study of the BaPb0.81Bi0.19O3 (001) surface. Phys Rev B Condens Matter 1994; 49:595-599. [PMID: 10009322 DOI: 10.1103/physrevb.49.595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Morris BC, Flavell WR, Mackrodt WC, Morris MA. Lattice parameter changes in the mixed-oxide system Ce1–xLaxO2–x/2: a combined experimental and theoretical study. ACTA ACUST UNITED AC 1993. [DOI: 10.1039/jm9930301007] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Calam DH, Flanagan RJ, Kaye CM, Sadler PJ, Ersser RS, Narayanaswamy R, Flockhart BD, Stevens JF, Flavell WR, Barra RS, Telling GM, Beveridge D, Cole RA, Rundell JH, Adams MJ, Miles DL. Book reviews. Analyst 1992. [DOI: 10.1039/an9921700219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Flavell WR, Laverty JH, Law DS, Lindsay R, Muryn CA, Flipse CF, Raiker GN, Wincott PL, Thornton G. Anomalous enhancement of Bi2Sr2CaCu2O8 Fermi-level states near the O 2s threshold. Phys Rev B Condens Matter 1991; 44:878-881. [PMID: 9999203 DOI: 10.1103/physrevb.44.878] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Golden MS, Golden SJ, Egdell RG, Flavell WR. Metal-to-non-metal transitions in high-temperature oxide superconductors monitored by photoelectron spectroscopy. ACTA ACUST UNITED AC 1991. [DOI: 10.1039/jm9910100063] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Flavell WR, Laverty JH, Law DS, Lindsay R, Muryn CA, Flipse CF, Raiker GN, Wincott PL, Thornton G. H2O adsorption on Bi2Sr2CaCu2O8(001). Phys Rev B Condens Matter 1990; 41:11623-11626. [PMID: 9993596 DOI: 10.1103/physrevb.41.11623] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Flavell WR, Egdell RG. Parallel valence- and core-level photoemission studies of the metal-to-nonmetal transition in YBa2Cu3O7-x. Phys Rev B Condens Matter 1989; 39:231-235. [PMID: 9947143 DOI: 10.1103/physrevb.39.231] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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