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6. Local nanoscale phase impurities are degradation sites in halide perovskites

Author

Macpherson, Stuart, Doherty, Tiarnan A. S., Winchester, Andrew J., Kosar, Sofiia, Johnstone, Duncan N., Chiang, Yu-Hsien, Galkowski, Krzysztof, Anaya, Miguel, Frohna, Kyle, Iqbal, Affan N., Nagane, Satyawan, Roose, Bart, Andaji-Garmaroudi, Zahra, Orr, Kieran W. P., Parker, Julia E., Midgley, Paul A., Dani, Keshav M., and Stranks, Samuel D.

Published
2022
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8. Revisiting metal fluorides as lithium-ion battery cathodes

Author

Hua, Xiao, Eggeman, Alexander S., Castillo-Martínez, Elizabeth, Robert, Rosa, Geddes, Harry S., Lu, Ziheng, Pickard, Chris J., Meng, Wei, Wiaderek, Kamila M., Pereira, Nathalie, Amatucci, Glenn G., Midgley, Paul A., Chapman, Karena W., Steiner, Ullrich, Goodwin, Andrew L., and Grey, Clare P.

Published
2021
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9. Enhancing the Conductivity and Thermoelectric Performance of Semicrystalline Conducting Polymers through Controlled Tie Chain Incorporation.

Author

Zhu, Wenjin, Qiu, Xinkai, Laulainen, Joonatan E. M., Un, Hio‐leng, Ren, Xinglong, Xiao, Mingfei, Freychet, Guillaume, Vacek, Petr, Tjhe, Dion, He, Qiao, Wood, William, Wang, Zichen, Zhang, Youcheng, Qu, Zhengkang, Asatryan, Jesika, Martin, Jaime, Heeney, Martin, McNeill, Christopher R., Midgley, Paul A., and Jacobs, Ian E.

Published
2024
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12. Microcavity-like exciton-polaritons can be the primary photoexcitation in bare organic semiconductors

Author

Pandya, Raj, Chen, Richard Y. S., Gu, Qifei, Sung, Jooyoung, Schnedermann, Christoph, Ojambati, Oluwafemi S., Chikkaraddy, Rohit, Gorman, Jeffrey, Jacucci, Gianni, Onelli, Olimpia D., Willhammar, Tom, Johnstone, Duncan N., Collins, Sean M., Midgley, Paul A., Auras, Florian, Baikie, Tomi, Jayaprakash, Rahul, Mathevet, Fabrice, Soucek, Richard, Du, Matthew, Alvertis, Antonios M., Ashoka, Arjun, Vignolini, Silvia, Lidzey, David G., Baumberg, Jeremy J., Friend, Richard H., Barisien, Thierry, Legrand, Laurent, Chin, Alex W., Yuen-Zhou, Joel, Saikin, Semion K., Kukura, Philipp, Musser, Andrew J., and Rao, Akshay

Published
2021
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13. Performance-limiting nanoscale trap clusters at grain junctions in halide perovskites

Author

Doherty, Tiarnan A. S., Winchester, Andrew J., Macpherson, Stuart, Johnstone, Duncan N., Pareek, Vivek, Tennyson, Elizabeth M., Kosar, Sofiia, Kosasih, Felix U., Anaya, Miguel, Abdi-Jalebi, Mojtaba, Andaji-Garmaroudi, Zahra, Wong, E Laine, Madéo, Julien, Chiang, Yu-Hsien, Park, Ji-Sang, Jung, Young-Kwang, Petoukhoff, Christopher E., Divitini, Giorgio, Man, Michael K. L., Ducati, Caterina, Walsh, Aron, Midgley, Paul A., Dani, Keshav M., and Stranks, Samuel D.

Published
2020
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17. On three-dimensional misorientation spaces

Author

Krakow, Robert, Bennett, Robbie J., Johnstone, Duncan N., Vukmanovic, Zoja, Solano-Alvarez, Wilberth, Lainé, Steven J., Einsle, Joshua F., Midgley, Paul A., Rae, Catherine M. F., and Hielscher, Ralf

Published
2017

21. Magnetite Morphology and Life on Mars

Author

Buseck, Peter R., Dunin-Borkowski, Rafal E., Devouard, Bertrand, Frankel, Richard B., McCartney, Martha R., Midgley, Paul A., Pósfai, Mihály, and Weyland, Matthew

Published
2001

27. Stabilized tilted-octahedra halide perovskites inhibit local formation of performance-limiting phases

Author

Doherty, Tiarnan A. S., Nagane, Satyawan, Kubicki, Dominik J., Jung, Young-Kwang, Johnstone, Duncan N., Iqbal, Affan N., Guo, Dengyang, Frohna, Kyle, Danaie, Mohsen, Tennyson, Elizabeth M., Macpherson, Stuart, Abfalterer, Anna, Anaya, Miguel, Chiang, Yu-Hsien, Crout, Phillip, Ruggeri, Francesco Simone, Collins, Sean, Grey, Clare P., Walsh, Aron, Midgley, Paul A., Stranks, Samuel D., Doherty, Tiarnan AS [0000-0003-1150-4012], Nagane, Satyawan [0000-0002-1146-4754], Kubicki, Dominik J [0000-0002-9231-6779], Jung, Young-Kwang [0000-0003-3848-8163], Johnstone, Duncan N [0000-0003-3663-3793], Iqbal, Affan N [0000-0002-7582-9011], Guo, Dengyang [0000-0002-2124-6208], Frohna, Kyle [0000-0002-2259-6154], Danaie, Mohsen [0000-0002-9325-7571], Tennyson, Elizabeth M [0000-0003-0071-8445], Macpherson, Stuart [0000-0003-3758-1198], Abfalterer, Anna [0000-0002-9423-8671], Anaya, Miguel [0000-0002-0384-5338], Chiang, Yu-Hsien [0000-0003-2767-3056], Crout, Phillip [0000-0001-5754-0938], Ruggeri, Francesco Simone [0000-0002-1232-1907], Collins, Sean [0000-0002-5151-6360], Grey, Clare P [0000-0001-5572-192X], Walsh, Aron [0000-0001-5460-7033], Midgley, Paul A [0000-0002-6817-458X], Stranks, Samuel D [0000-0002-8303-7292], and Apollo - University of Cambridge Repository

Subjects
3403 Macromolecular and Materials Chemistry, Multidisciplinary, 34 Chemical Sciences, Organic Chemistry, 3406 Physical Chemistry, Life Science, Organische Chemie
Abstract

Efforts to stabilize photoactive formamidinium (FA)–based halide perovskites for perovskite photovoltaics have focused on the growth of cubic formamidinium lead iodide (a-FAPbI3) phases by empirically alloying with cesium, methylammonium (MA) cations, or both. We show that such stabilized FA-rich perovskites are noncubic and exhibit ~2° octahedral tilting at room temperature. This tilting, resolvable only with the use of local nanostructure characterization techniques, imparts phase stability by frustrating transitions from photoactive to hexagonal phases. Although the bulk phase appears stable when examined macroscopically, heterogeneous cation distributions allow microscopically unstable regions to form; we found that these transitioned to hexagonal polytypes, leading to local trap-assisted performance losses and photoinstabilities. Using surface-bound ethylenediaminetetraacetic acid, we engineered an octahedral tilt into pure a-FAPbI3 thin films without any cation alloying. The templated photoactive FAPbI3 film was extremely stable against thermal, environmental, and light stressors.

Published
2021

28. Publisher Correction: Liquid phase blending of metal-organic frameworks

Author

Longley, Louis, Collins, Sean M., Zhou, Chao, Smales, Glen J., Norman, Sarah E., Brownbill, Nick J., Ashling, Christopher W., Chater, Philip A., Tovey, Robert, Schönlieb, Carola-Bibiane, Headen, Thomas F., Terrill, Nicholas J., Yue, Yuanzheng, Smith, Andrew J., Blanc, Frédéric, Keen, David A., Midgley, Paul A., and Bennett, Thomas D.

Published
2018
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29. Liquid phase blending of metal-organic frameworks

Author

Longley, Louis, Collins, Sean M., Zhou, Chao, Smales, Glen J., Norman, Sarah E., Brownbill, Nick J., Ashling, Christopher W., Chater, Philip A., Tovey, Robert, Schönlieb, Carola-Bibiane, Headen, Thomas F., Terrill, Nicholas J., Yue, Yuanzheng, Smith, Andrew J., Blanc, Frédéric, Keen, David A., Midgley, Paul A., and Bennett, Thomas D.

Published
2018
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39. Local Nanoscale Defective Phase Impurities Are the Sites of Degradation in Halide Perovskite Devices

Author

Macpherson, Stuart, Doherty, Tiarnan A. S., Winchester, Andrew J., Kosar, Sofiia, Johnstone, Duncan N., Chiang, Yu-Hsien, Galkowski, Krzystof, Anaya, Miguel, Frohna, Kyle, Iqbal, Affan N., Roose, Bart, Andaji-Garmaroudi, Zahra, Midgley, Paul A., Dani, Keshav M., and Stranks, Samuel D.

Subjects
Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Applied Physics (physics.app-ph), Physics - Applied Physics, Optics (physics.optics), Physics - Optics
Abstract

Halide perovskites excel in the pursuit of highly efficient thin film photovoltaics, with power conversion efficiencies reaching 25.5% in single junction and 29.5% in tandem halide perovskite/silicon solar cell configurations. Operational stability of perovskite solar cells remains a barrier to their commercialisation, yet a fundamental understanding of degradation processes, including the specific sites at which failure mechanisms occur, is lacking. Recently, we reported that performance-limiting deep sub-bandgap states appear in nanoscale clusters at particular grain boundaries in state-of-the-art $Cs_{0.05}FA_{0.78}MA_{0.17}Pb(I_{0.83}Br_{0.17})_{3}$ (MA=methylammonium, FA=formamidinium) perovskite films. Here, we combine multimodal microscopy to show that these very nanoscale defect clusters, which go otherwise undetected with bulk measurements, are sites at which degradation seeds. We use photoemission electron microscopy to visualise trap clusters and observe that these specific sites grow in defect density over time under illumination, leading to local reductions in performance parameters. Scanning electron diffraction measurements reveal concomitant structural changes at phase impurities associated with trap clusters, with rapid conversion to metallic lead through iodine depletion, eventually resulting in pinhole formation. By contrast, illumination in the presence of oxygen reduces defect densities and reverses performance degradation at these local clusters, where phase impurities instead convert to amorphous and electronically benign lead oxide. Our work shows that the trapping of charge carriers at sites associated with phase impurities, itself reducing performance, catalyses redox reactions that compromise device longevity. Importantly, we reveal that both performance losses and intrinsic degradation can be mitigated by eliminating these defective clusters., 23 pages, 3 figures, Stuart Macpherson and Tiarnan A. S. Doherty contributed equally

Published
2021

43. Three-dimensional imaging of localized surface plasmon resonances of metal nanoparticles

Author

Nicoletti, Olivia, de la Pena, Francisco, Leary, Rowan K., Holland, Daniel J., Ducati, Caterina, and Midgley, Paul A.

Subjects
Surface plasmon resonance -- Usage -- Methods -- Optical properties, Silver -- Optical properties -- Structure -- Usage, Nanoparticles -- Optical properties -- Structure -- Methods -- Usage, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Localized surface plasmon resonances of an individual silver nanocube are reconstructed in three dimensions using electron energy-loss spectrum imaging, resulting in a better understanding of the optical response of noble-metal nanoparticles. Observing surface excitations for nano-optics Metal nanoparticles exhibit a range of striking and useful optical properties thanks to the excitation of localized surface plasmon resonances (LSPRs). But the precise relationship between the three-dimensional structure of the nanoparticles and the resulting LSPRs can be hard to determine. Paul Midgley and colleagues have developed a spectrally sensitive imaging technique, based on electron energy-loss spectroscopy, that permits three-dimensional visualization of many of the key features associated with these LSPRs. With this technique, the interplay between the LSPRs, nanoparticle structure and substrate-nanoparticle interactions can be directly probed. This study focuses on silver nanocubes, but the method demonstrated is applicable to similar plasmonic phenomena across all metal nanoparticles. The remarkable optical properties of metal nanoparticles are governed by the excitation of localized surface plasmon resonances (LSPRs). The sensitivity of each LSPR mode, whose spatial distribution and resonant energy depend on the nanoparticle structure, composition and environment, has given rise to many potential photonic, optoelectronic, catalytic, photovoltaic, and gas- and bio-sensing applications.sup.1,2,3. However, the precise interplay between the three-dimensional (3D) nanoparticle structure and the LSPRs is not always fully understood and a spectrally sensitive 3D imaging technique is needed to visualize the excitation on the nanometre scale. Here we show that 3D images related to LSPRs of an individual silver nanocube can be reconstructed through the application of electron energy-loss spectrum imaging.sup.4, mapping the excitation across a range of orientations, with a novel combination of non-negative matrix factorization.sup.5,6, compressed sensing.sup.7,8 and electron tomography.sup.9. Our results extend the idea of substrate-mediated hybridization of dipolar and quadrupolar modes predicted by theory, simulations, and electron and optical spectroscopy.sup.10,11,12, and provide experimental evidence of higher-energy mode hybridization. This work represents an advance both in the understanding of the optical response of noble-metal nanoparticles and in the probing, analysis and visualization of LSPRs., Author(s): Olivia Nicoletti [sup.1] , Francisco de la Peña [sup.1] , Rowan K. Leary [sup.1] , Daniel J. Holland [sup.2] , Caterina Ducati [sup.1] , Paul A. Midgley [sup.1] Author [...]

Published
2013
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48. Density-based clustering of crystal orientations and misorientations and the orix python library

Author

Johnstone, Duncan N., Martineau, Ben H., Crout, Phillip, Midgley, Paul A., and Eggeman, Alexander S.

Subjects
Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences
Abstract

Crystal orientation mapping experiments typically measure orientations that are similar within grains and misorientations that are similar along grain boundaries. Such (mis)orientation data will cluster in (mis)orientation space and clusters are more pronounced if preferred orientations or special orientation relationships are present. Here, cluster analysis of (mis)orientation data is described and demonstrated using distance metrics incorporating crystal symmetry and the density-based clustering algorithm DBSCAN. Frequently measured (mis)orientations are identified as corresponding to grains, grain boundaries or orientation relationships, which are visualised both spatially and in three-dimensional (mis)orientation spaces. A new open-source python library, orix, is also reported.

Published
2020

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