https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/ The latest from Physics » Ultrafast & Terahertz Photonics: Publications (tag [2020]) en-GB (C) 2026 University of Warwick Mon, 30 Mar 2026 08:11:42 GMT http://blogs.law.harvard.edu/tech/rss SiteBuilder2, University of Warwick, http://go.warwick.ac.uk/sitebuilder 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 biomedical highlight Lloyd-Hughes MacPherson Milot nanomaterials perovskites photoluminescence review THz components THz imaging THz spectroscopy ultrafast Untagged https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/?newsItem=8a17841b76674c940176a3c6f61b624a <p><img src="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/monti2020.png?maxWidth=250" alt="Hot carrier temperatures" style="margin-right: 10px;" border="0" align="right" /></p> <p><strong>M. Monti</strong>, K.D.G.I. Jayawardena, <strong>E. Butler-Caddle, </strong>R.M.I. Bandara, J.M. Woolley, <strong>M. Staniforth</strong>, S.R.P. Silva and<strong> J. Lloyd-Hughes</strong><br /> Phys. Rev. B <strong><span class="citation_volume">102</span></strong> 245204 (Dec 2020) [ <a style="text-decoration: none;" href="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/monti2020.pdf">pdf</a> ] [ <a style="text-decoration: none;" href="https://dx.doi.org/10.1103/PhysRevB.102.245204" target="_blank" rel="noopener">ref </a>]</p> <p><button class="abstractButton" onclick="showHide('monti2020')">Show abstract</button></p> <div id="monti2020" style="display: none;">The electron-phonon interaction controls the intrinsic mobility of charges in metal halide perovskites, and determines the rate at which carriers lose energy. Here, the carrier mobility and cooling dynamics were directly examined using a combination of ultrafast transient absorption spectroscopy and optical pump, THz probe spectroscopy, in perovskites with different lead and tin content, and for a range of carrier densities. Significantly, the carrier mobility in the “hot phonon bottleneck” regime, where the LO phonon bath keeps carriers warm, was found to be similar to the mobility of cold carriers. A model was developed that provides a quantitative description of the experimental carrier cooling dynamics, including electron-phonon coupling, phonon-phonon coupling and the Auger mechanism. In the Pb and Sn alloy the duration of the hot carrier regime was extended as a result of the slower decay of optical phonons. The findings offer an intuitive link between macroscopic properties and the underlying microscopic energy transfer processes, and suggest new routes to control the carrier cooling process in metal halide perovskites to optimize optoelectronic devices.</div> <div align="left"><img src="https://api.elsevier.com/content/abstract/citation-count?doi=10.1103/PhysRevB.102.245204&amp;httpAccept=image%2Fjpeg&amp;apiKey=23942728d429d8cd622400c4a7485a23" border="0" /></div> <div class="altmetric-embed" data-badge-popover="right" data-badge-type="2" data-doi="10.1103/PhysRevB.102.245204" data-hide-no-mentions="true"></div> THz spectroscopy photoluminescence perovskites Lloyd-Hughes 2020 Thu, 24 Dec 2020 10:00:00 GMT 8a17841b76674c940176a3c6f61b624a https://iopscience.iop.org/article/10.1088/2515-7647/abcb71 <p><img src="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/lindley-hatcher2021.jpg?maxWidth=200" alt="Diagram" style="margin-right: 20px;" border="0" align="right" /></p> <p><strong>H. Lindley-Hatcher</strong>, <strong>A. I. Hernandez-Serrano</strong>, J. Wang, J. Cebrian, J. Hardwicke and <strong>E. Pickwell-MacPherson</strong><br /> J. Phys. Photonics <strong>3</strong>, 014001 (December 2020) <button class="abstractButton" onclick="location.href='https://iopscience.iop.org/article/10.1088/2515-7647/abcb71';">web</button> <button class="abstractButton" onclick="location.href='https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/lindley-hatcher-2021.pdf';">pdf</button> <button class="abstractButton" onclick="showHide('lindley-hatcher2020b')">Show abstract</button></p> <div id="lindley-hatcher2020b" style="display: none;">Terahertz (THz) in vivo reflection imaging can be used to assess the water content of the surface of the skin. This study presents the results of treating 20 subjects with aqueous, anhydrous and water-oil emulsion samples and observing the changes induced in the skin using THz sensing. These regions were also measured with a corneometer, the present gold standard for skin hydration assessment within the cosmetics industry. We find that THz sensing is effective at observing the presence of oil and water on the surface of the skin, these results can be verified with the measurements of capacitance taken by the corneometer. The THz measurements reveal a distinction between the responses of subjects with initially dry or well hydrated skin, this observation is particularly noticeable with the oil-based samples. Additionally, moderate correlation was found between the THz reflected amplitude and capacitance of untreated skin with a correlation coefficient of r = −0.66, suggesting THz sensing has promising potential for assessing skin hydration.</div> <div class="altmetric-embed" data-badge-popover="right" data-badge-type="2" data-doi="10.1088/2515-7647/abcb71" data-hide-no-mentions="true"></div> <div><img src="https://api.elsevier.com/content/abstract/citation-count?doi=10.1088/2515-7647/abcb71&amp;httpAccept=image%2Fjpeg&amp;apiKey=23942728d429d8cd622400c4a7485a23" border="0" /></div> THz spectroscopy MacPherson biomedical 2020 Mon, 14 Dec 2020 13:00:00 GMT 8a1785d87b77d89c017be4349fb3369d https://onlinelibrary.wiley.com/doi/10.1002/adpr.202000024 <p><img src="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/chen2020.png?maxWidth=200" alt="Diagram" style="margin-right: 20px;" border="0" align="right" /></p> <p>X. Chen<strong>,</strong> Q. Sun, J. Wang,<strong> H. Lindley-Hatcher, </strong><strong>E. Pickwell-MacPherson</strong><br /> Adv. Photonics Res. 2000024 (November 2020) [ <a style="text-decoration: none;" href="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/chen2020.pdf" target="_blank" rel="noopener">pdf</a> ] [ <a style="text-decoration: none;" href="https://onlinelibrary.wiley.com/doi/10.1002/adpr.202000024" target="_blank" rel="noopener">ref </a>] <button class="abstractButton" onclick="showHide('chen2020')">Show abstract</button></p> <div id="chen2020" style="display: none;">The noninvasive and water‐sensitive characteristics of terahertz (THz) light make it highly attractive for in vivo studies, especially for skin applications. However, THz instrumentation has not been developed sufficiently to fully explore all the potential applications arising: current systems cannot obtain uncorrelated reflections from multiple configurations to determine the complicated structure of living tissues. Herein, this bottleneck is overcome by implementing a novel ellipsometry configuration able to efficiently provide four complementary sets of spectral ratios, significantly enhancing characterization capabilities. An accurate model of the skin is established and validated. The anisotropy of the stratum corneum (SC) caused by its cellular structure is verified both theoretically and experimentally. The in vivo response of skin on the volar forearm to occlusion is observed by the dynamic changes in the SC and the epidermis. In addition, the THz dispersion and birefringence sensitively probe the level of hydration and the cellular inhomogeneity, producing results in good agreement with microscope images and the biological processes of the SC. The presented technique offers a brand‐new functionality in extracting insightful structural information from complex systems, significantly extending the versatility of THz spectroscopy.</div> <div class="altmetric-embed" data-badge-popover="right" data-badge-type="2" data-doi="10.1002/adpr.202000024" data-hide-no-mentions="true"></div> <div><img src="https://api.elsevier.com/content/abstract/citation-count?doi=10.1002/adpr.202000024&amp;httpAccept=image%2Fjpeg&amp;apiKey=23942728d429d8cd622400c4a7485a23" border="0" /></div> THz spectroscopy MacPherson biomedical 2020 Tue, 10 Nov 2020 10:00:00 GMT 8a1785d776674c92017679b6e5164401 https://iopscience.iop.org/article/10.1088/1361-6528/abbce8/meta <p><span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">U. Banin</span></span>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">N. Waiskopf</span></span>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">L. Hammarström</span></span>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">G. Boschloo</span></span>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">M. Freitag</span></span>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">E.M.J. Johansson</span></span>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">J. Sá</span>, </span><span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">H. Tian</span></span>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">M.B. Johnston</span></span>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">L.M. Herz</span></span><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation">, <strong><span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">R.L. Milot</span></span></strong>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">M.G. Kanatzidis</span>,</span></span></span><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation"> <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">W. Ke</span></span>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">I. Spanopoulos</span></span>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">K.L. Kohlstedt,</span></span></span></span><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation"> <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">G.C. Schatz</span></span></span></span><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation">, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">N. Lewis</span>, </span></span></span><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation"><span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">T. Meyer</span></span></span></span><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation">, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">A.J. Nozik</span>, </span></span></span><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation"><span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">M.C. Beard</span></span></span></span><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation">, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">F. Armstrong</span>, </span></span></span><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation"><span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">C. F. Megarity</span></span>, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">C.A. Schmuttenmaer</span></span></span></span><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation">, <span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name">V. S. Batista, and G.W. Brudvig</span></span></span></span><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation"><span itemtype="http://schema.org/Person" itemprop="author" class="nowrap"><span itemprop="name"><br /> </span></span></span></span></p> <p><span class="reveal-container reveal-plus-icon reveal-enabled"><span class="reveal-content reveal-no-animation"><span itemtype="http://schema.org/Person" itemprop="author" class="nowrap">Nanotechnology <strong>32</strong> 042003 (Nov 2020) [<a href="https://iopscience.iop.org/article/10.1088/1361-6528/abbce8/pdf" target="_blank" rel="noopener">pdf</a>] [<a href="https://iopscience.iop.org/article/10.1088/1361-6528/abbce8/meta" target="_blank" rel="noopener">ref</a>]</span></span></span></p> <p><button class="abstractButton" onclick="showHide('banin2020')">Show abstract</button></p> <div id="banin2020" style="display: none;">This roadmap on Nanotechnology for Catalysis and Solar Energy Conversion focuses on the application of nanotechnology in addressing the current challenges of energy conversion: 'high efficiency, stability, safety, and the potential for low-cost/scalable manufacturing' to quote from the contributed article by Nathan Lewis. This roadmap focuses on solar-to-fuel conversion, solar water splitting, solar photovoltaics and bio-catalysis. It includes dye-sensitized solar cells (DSSCs), perovskite solar cells, and organic photovoltaics. Smart engineering of colloidal quantum materials and nanostructured electrodes will improve solar-to-fuel conversion efficiency, as described in the articles by Waiskopf and Banin and Meyer. Semiconductor nanoparticles will also improve solar energy conversion efficiency, as discussed by Boschloo <i>et al</i> in their article on DSSCs. Perovskite solar cells have advanced rapidly in recent years, including new ideas on 2D and 3D hybrid halide perovskites, as described by Spanopoulos <i>et al</i> 'Next generation' solar cells using multiple exciton generation (MEG) from hot carriers, described in the article by Nozik and Beard, could lead to remarkable improvement in photovoltaic efficiency by using quantization effects in semiconductor nanostructures (quantum dots, wires or wells). These challenges will not be met without simultaneous improvement in nanoscale characterization methods. Terahertz spectroscopy, discussed in the article by Milot <i>et al</i> is one example of a method that is overcoming the difficulties associated with nanoscale materials characterization by avoiding electrical contacts to nanoparticles, allowing characterization during device operation, and enabling characterization of a single nanoparticle. Besides experimental advances, computational science is also meeting the challenges of nanomaterials synthesis. The article by Kohlstedt and Schatz discusses the computational frameworks being used to predict structure&ndash;property relationships in materials and devices, including machine learning methods, with an emphasis on organic photovoltaics. The contribution by Megarity and Armstrong presents the 'electrochemical leaf' for improvements in electrochemistry and beyond. In addition, biohybrid approaches can take advantage of efficient and specific enzyme catalysts. These articles present the nanoscience and technology at the forefront of renewable energy development that will have significant benefits to society.</div> THz spectroscopy nanomaterials Milot perovskites 2020 review Mon, 09 Nov 2020 17:46:00 GMT 8a1785d7756ec68b0175ae1e19077848 https://www.osapublishing.org/boe/abstract.cfm?uri=boe-11-8-4484 <p><img src="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/wang2020.png?maxWidth=200" alt="Diagram" border="0" align="right" /></p> <p>J. Wang<strong>, H. Lindley-Hatcher, </strong>K. Liu, <strong>E. Pickwell-MacPherson</strong><br /> Biomedical Optics Express <strong>11</strong> 4484 (August 2020) [ <a style="text-decoration: none;" href="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/Wang2020.pdf" target="_blank" rel="noopener">pdf</a> ] [ <a style="text-decoration: none;" href="https://doi.org/10.1364/BOE.394436" target="_blank" rel="noopener">ref </a>] <button class="abstractButton" onclick="showHide('wang2020')">Show abstract</button></p> <div id="wang2020" style="display: none;">Transdermal drug delivery (TDD) is widely used for painless dosing due to its minimally invasive nature compared to hypodermic needle injection and its avoidance of the gastrointestinal tract. However, the stratum corneum obstructs the permeation of drugs into skin. Microneedle and nanoneedle patches are ways to enhance this permeation. In this work, terahertz (THz) imaging is utilized to compare the efficacy of different TDD methods including topical application and via a needle patch. Our work shows the feasibility and potential of using THz imaging to quantify and evaluate different transdermal application methods.</div> <div class="altmetric-embed" data-badge-popover="right" data-badge-type="2" data-doi="10.1364/BOE.394436" data-hide-no-mentions="true"></div> <div><img src="https://api.elsevier.com/content/abstract/citation-count?doi=10.1364/BOE.394436&amp;httpAccept=image%2Fjpeg&amp;apiKey=23942728d429d8cd622400c4a7485a23" border="0" /></div> MacPherson THz imaging biomedical 2020 Thu, 24 Sep 2020 09:01:00 GMT 8a17841a74bb9e8e0174bf5886c00daa https://www.osapublishing.org/osac/fulltext.cfm?uri=osac-3-9-2407&id=437582 <p><img src="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/arturo2020.jpeg?maxWidth=200" alt="Diagram" style="margin-right: 20px;" border="0" align="right" /></p> <p><strong>A. I. Hernandez-Serrano</strong>, S. J. Leigh and <strong>E. Pickwell-MacPherson</strong><br /> OSA Continuum <strong>3</strong>, 2407 (August 2020) <button class="abstractButton" onclick="location.href='https://doi.org/10.1364/OSAC.399389';">web</button> <button class="abstractButton" onclick="location.href='https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/arturo2020.pdf';">pdf</button> <button class="abstractButton" onclick="showHide('arturo2020')">Show abstract</button></p> <div id="arturo2020" style="display: none;">In this research, we present the design, fabrication, and experimental validation of 3D printed bandpass filters and mux/demux elements for terahertz frequencies. The filters consist of a set of in-line polystyrene (PS) rectangular waveguides, separated by 100 µm, 200 µm, and 400 µm air gaps. The principle of operation for the proposed filters resides in coupled-mode theory. Q-factors of up to 3.4 are observed, and additionally, the experimental evidence demonstrates that the Q-factor of the filters can be improved by adding fiber elements to the design. Finally, using two independent THz broadband channels, we demonstrate the first mux/demux device based on 3D printed in-line filters for the THz range. This approach represents a fast, robust, and low-cost solution for the next generation of THz devices for communications.</div> <div class="altmetric-embed" data-badge-popover="right" data-badge-type="2" data-doi="10.1364/OSAC.399389" data-hide-no-mentions="true"></div> <div><img src="https://api.elsevier.com/content/abstract/citation-count?doi=10.1364/OSAC.399389&amp;httpAccept=image%2Fjpeg&amp;apiKey=23942728d429d8cd622400c4a7485a23" border="0" /></div> THz components MacPherson 2020 Tue, 25 Aug 2020 11:45:00 GMT 8a1785d77b77d622017be424635e002a https://dx.doi.org/10.1021/acs.jpclett.0c01806 <p><img src="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/coxon2020.png?maxWidth=200" alt="Ultrafast shakedown" align="right" border="0" /><strong>D.J.L. Coxon</strong>, <strong>M. Staniforth</strong>, B.G. Breeze, S.E. Greenough, J.P. Goss, <strong>M. Monti</strong>, <strong>J. Lloyd-Hughes</strong>, V.G. Stavros, and M.E. Newton<br /> J. Phys. Chem. Lett. <span class="cit-issue">11, 6677</span><strong><span class="citation_volume"></span></strong> (July 2020) [ <a style="text-decoration: none;" href="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/coxon-2020-withsi.pdf" target="_blank" rel="noopener">pdf (with SI)</a> ] [ <a style="text-decoration: none;" href="https://doi.org/10.1021/acs.jpclett.0c01806" target="_blank" rel="noopener">ref </a>]</p> <p><button class="abstractButton" onclick="showHide('coxon2020')">Show abstract</button></p> <div id="coxon2020" style="display: none;">Atomic-scale defects can control the exploitable optoelectronic performance of crystalline materials, and several point defects in diamond are emerging functional components for a range of quantum technologies. Nitrogen and hydrogen are common impurities incorporated into diamond, and there is a family of defects that includes both. The N₃VH⁰ defect is a lattice vacancy where three nearest neighbor carbon atoms are replaced with nitrogen atoms and a hydrogen is bonded to the remaining carbon. It is regularly observed in natural and high-temperature annealed synthetic diamond, and gives rise to prominent absorption features in the mid-infrared. Here, we combine time- and spectrally-resolved infrared absorption spectroscopy to yield unprecedented insight into the N₃VH⁰ defect’s vibrational dynamics following infrared excitation of the C&ndash;H stretch. In doing so, we gain fundamental information about the energies of quantized vibrational states, and corroborate our results with theory. We map out, for the first time, energy relaxation pathways, which include multiphonon relaxation processes and anharmonic coupling to the C&ndash;H bend mode. These advances provide new routes to quantify and probe atomic-scale defects.</div> <div align="left"><img src="https://api.elsevier.com/content/abstract/citation-count?doi=10.1021/acs.jpclett.0c01806&amp;httpAccept=image%2Fjpeg&amp;apiKey=23942728d429d8cd622400c4a7485a23" border="0" /></div> <div class="altmetric-embed" data-badge-popover="right" data-badge-type="2" data-doi="10.1021/acs.jpclett.0c01806" data-hide-no-mentions="true"><br /> <br /> </div> nanomaterials Lloyd-Hughes 2020 Fri, 17 Jul 2020 21:00:00 GMT 8a17841a737ac5630173b61fd66c2c5a https://dx.doi.org/10.1021/acs.nanolett.0c02063 <p>W. Dong, J.J.P. Peters, D. Rusu, <strong>M. Staniforth</strong>, A. Brunier,<strong> J. Lloyd-Hughes</strong>, A.M. Sanchez and M. Alexe<br /> Nano Lett. <span class="citation_volume"></span><strong><span class="cit-volume">20</span></strong><span class="cit-issue"> 8, 6045</span> (July 2020) [ <a style="text-decoration: none;" href="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/dong2020.pdf" target="_blank" rel="noopener">pdf</a> ] [ <a style="text-decoration: none;" href="https://doi.org/10.1021/acs.nanolett.0c02063" target="_blank" rel="noopener">ref </a>]</p> <p><img src="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/wendong.gif" alt="Emergent antipolar phase" width="300" align="right" border="0" /></p> <p><button class="abstractButton" onclick="showHide('dong2020')">Show abstract</button></p> <div id="dong2020" style="display: none;">Ferroelectric&ndash;paraelectric superlattices show emerging new states, such as polar vortices, through the interplay and different energy scales of various thermodynamic constraints. By introducing magnetic coupling at BiFeO₃&ndash;La_0.7Sr_0.3MnO₃ interfaces epitaxially grown on SrTiO₃ substrate, we find, for the first time in thin films, a sub-nanometer thick lamella-like BiFeO₃. The emergent phase is characterized by an arrangement of a two unit cell thick lamella-like structure featuring antiparallel polarization, resulting an antiferroelectric-like structure typically associated with a morphotropic phase transition. The antipolar phase is embedded within a nominal <i>R</i>3<i>c</i> structure and is independent of the BiFeO₃ thickness (4&ndash;30 unit cells). Moreover, the superlattice structure with the morphotropic phase demonstrates azimuth-independent second harmonic generation responses, indicating a change of overall symmetry mediated by a delicate spatial distribution of the emergent phase. This work enriches the understanding of a metastable state manipulated by thermodynamic constraints by lattice strain and magnetic coupling.</div> <div align="left"><img src="https://api.elsevier.com/content/abstract/citation-count?doi=10.1021/acs.nanolett.0c02063&amp;httpAccept=image%2Fjpeg&amp;apiKey=23942728d429d8cd622400c4a7485a23" border="0" /></div> <div class="altmetric-embed" data-badge-popover="right" data-badge-type="2" data-doi="10.1021/acs.nanolett.0c02063" data-hide-no-mentions="true"><br /> <br /> </div> nanomaterials Lloyd-Hughes 2020 Tue, 14 Jul 2020 20:05:00 GMT 8a1785d8734808fa01734eee99442121 https://www.nature.com/articles/s41467-020-16370-x <p>R. I. Stantchev, X. Yu, T. Blu and <strong>E. Pickwell-MacPherson</strong><br /> Nature Communications <strong>11</strong> 2535 (May 2020) [ <a style="text-decoration: none;" href="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/stantchev2020.pdf">pdf</a> ] [ <a style="text-decoration: none;" href="https://doi.org/10.1038/s41467-020-16370-x">ref </a>] <img src="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/stantchev2020.png?maxWidth=300" alt="Stantchev 2020" style="margin-right: 10px;" border="0" align="right" /> <button class="abstractButton" onclick="showHide('stanchev2020')">abstract</button></p> <div id="stanchev2020" style="display: none;">Terahertz (THz) radiation is poised to have an essential role in many imaging applications, from industrial inspections to medical diagnosis. However, commercialization is prevented by impractical and expensive THz instrumentation. Single-pixel cameras have emerged as alternatives to multi-pixel cameras due to reduced costs and superior durability. Here, by optimizing the modulation geometry and post-processing algorithms, we demonstrate the acquisition of a THz-video (32 × 32 pixels at 6 frames-per-second), shown in real-time, using a single-pixel fiber-coupled photoconductive THz detector. A laser diode with a digital micromirror device shining visible light onto silicon acts as the spatial THz modulator. We mathematically account for the temporal response of the system, reduce noise with a lock-in free carrier-wave modulation and realize quick, noise-robust image undersampling. Since our modifications do not impose intricate manufacturing, require long post-processing, nor sacrifice the time-resolving capabilities of THz-spectrometers, their greatest asset, this work has the potential to serve as a foundation for all future single-pixel THz imaging systems.</div> <div class="altmetric-embed" data-badge-popover="right" data-badge-type="2" data-doi="10.1038/s41467-020-16370-x" data-hide-no-mentions="true"></div> <div><img src="https://api.elsevier.com/content/abstract/citation-count?doi=10.1038/s41467-020-16370-x&amp;httpAccept=image%2Fjpeg&amp;apiKey=23942728d429d8cd622400c4a7485a23" border="0" /></div> THz components MacPherson 2020 Thu, 09 Jul 2020 21:23:00 GMT 8a1785d87328577001733575f0116246 https://doi.org/10.1039/D0EE00132E <p>M. T. Klug, <strong>R. L. Milot</strong>, J.B. Patel, T. Green, H. C. Sansom, M. D. Farrar, A. J. Ramadan, S. Martani, Z. Wang, B. Wenger, J. M. Ball, L. Langshaw, A. Petrozza, M. B. Johnston, L. M. Herz and H. J. Snaith<br /> Energy &amp; Environmental Science (May 2020) <button class="abstractButton" onclick="location.href='https://doi.org/10.1039/D0EE00132E';">web</button> <button class="abstractButton" onclick="location.href='https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/klug2020.pdf';">pdf</button> <button class="abstractButton" onclick="showHide('klug2020')">Show abstract</button></p> <p><img src="https://warwick.ac.uk/fac/sci/physics/research/condensedmatt/ultrafastphotonics/publications/klug2020.gif" alt="Klug 2020" style="margin-right: 5px; margin-left: 5px;" width="222" border="0" align="right" /></p> <div id="klug2020" style="display: none;">Current designs for all-perovskite multi-junction solar cells require mixed-metal Pb&ndash;Sn compositions to achieve narrower band gaps than are possible with their neat Pb counterparts. The lower band gap range achievable with mixed-metal Pb&ndash;Sn perovskites also encompasses the 1.3 to 1.4 eV range that is theoretically ideal for maximising the efficiency of single-junction devices. Here we examine the optoelectronic quality and photovoltaic performance of the ((HC(NH<small>₂</small>)<small>₂</small>)<small>_0.83</small>Cs<small>_0.17</small>)(Pb<small>_{1−<em>y</em>}</small>Sn<small>_<em>y</em></small>)I<small>₃</small> family of perovskite materials across the full range of achievable band gaps by substituting between 0.001% and 70% of the Pb content with Sn. We reveal that a compositional range of “defectiveness” exists when Sn comprises between 0.5% and 20% of the metal content, but that the optoelectronic quality is restored for Sn content between 30&ndash;50%. When only 1% of Pb content is replaced by Sn, we find that photoconductivity, photoluminescence lifetime, and photoluminescence quantum efficiency are reduced by at least an order of magnitude, which reveals that a small concentration of Sn incorporation produces trap sites that promote non-radiative recombination in the material and limit photovoltaic performance. While these observations suggest that band gaps between 1.35 and 1.5 eV are unlikely to be useful for optoelectronic applications without countermeasures to improve material quality, highly efficient narrower band gap absorber materials are possible at or below 1.33 eV. Through optimising single-junction photovoltaic devices with Sn compositions of 30% and 50%, we respectively demonstrate a 17.6% efficient solar cell with an ideal single-junction band gap of 1.33 eV and an 18.1% efficient low band gap device suitable for the bottom absorber in all-perovskite multi-junction cells.</div> <div align="left"><img src="https://api.elsevier.com/content/abstract/citation-count?doi=10.1039/D0EE00132E&amp;httpAccept=image%2Fjpeg&amp;apiKey=23942728d429d8cd622400c4a7485a23" border="0" /></div> <div class="altmetric-embed" data-badge-popover="right" data-badge-type="2" data-doi="10.1039/D0EE00132E" data-hide-no-mentions="true"><br /> <br /> </div> THz spectroscopy photoluminescence Milot perovskites 2020 Fri, 01 May 2020 12:00:00 GMT 8a1785d774f8c62a017502f1a46a4f97