68 results found
Ward MD, Shi W, Gasparini N, et al., 2022, Best practices in the measurement of circularly polarised photodetectors (vol 10, pg 10452, 2022), JOURNAL OF MATERIALS CHEMISTRY C, ISSN: 2050-7526
Wade J, 2022, How you can change gender stereotypes about physicists, NATURE REVIEWS PHYSICS, Vol: 4, Pages: 690-691
Wade J, Salerno F, Kilbride R, et al., 2022, Controlling anisotropic properties by manipulating the orientation of chiral small molecules, Nature Chemistry, Vol: 14, Pages: 1383-1389, ISSN: 1755-4330
Chiral π-conjugated molecules bring new functionality to technological applications and represent an exciting, rapidly expanding area of research. Their functional properties, such as the absorption and emission of circularly polarised light or the transport of spin-polarised electrons, are highly anisotropic. As a result, the orientation of chiral molecules criticallydetermines the functionality and efficiency of chiral devices. Here we present a strategy to control the orientation of a small chiral molecule (2,2’-dicyanohelicene, CN6H): the use of organic and inorganic templating layers. Such templating layers can either force CN6H molecules to adopt a face-on orientation and self-assemble into upright supramolecular columns oriented with their helical axis perpendicular to the substrate, or an edge-onorientation with parallel-lying supramolecular columns. Through such control, we show that low- and high-energy chiroptical responses can be independently ‘turned on’ or ‘turned off’. The templating methodologies described here provide a simple way to engineer orientational control, and by association, anisotropic functional properties of chiral molecular systems for a range of emerging technologies.
Wade J, Rabey IM, Smith A, et al., 2022, Lessons from a UK research school for Black physicists and engineers, Nature Reviews Materials, Vol: 7, Pages: 927-928, ISSN: 2058-8437
Wade J, 2022, Why I wrote a children's book about nanoscience, NATURE, Vol: 608, Pages: S14-S14, ISSN: 0028-0836
Ward MD, Shi W, Gasparini N, et al., 2022, Best practices in the measurement of circularly polarised photodetectors, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 10, Pages: 10452-10463, ISSN: 2050-7526
Yan H, Wade J, Wan L, et al., 2022, Enhancing hole carrier injection <i>via</i> low electrochemical doping on circularly polarized polymer light-emitting diodes, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 10, Pages: 9512-9520, ISSN: 2050-7526
Wan L, Wade J, Shi X, et al., 2022, Highly Efficient Inverted Circularly Polarized Organic Light Emitting Diodes (vol 12, pg 39471, 2020), ACS APPLIED MATERIALS & INTERFACES, Vol: 14, Pages: 27523-27523, ISSN: 1944-8244
Wan L, Wade J, Salerno F, et al., 2022, Inverting the Handedness of Circularly Polarized Luminescence from Light-Emitting Polymers Using Film Thickness (vol 13, pg 8099, 2019), ACS NANO, Vol: 16, Pages: 9962-9963, ISSN: 1936-0851
Wade J, Zaringhalam M, 2022, We need to rethink scientific awards Comment, PHYSICS WORLD, Vol: 35, Pages: 25-25, ISSN: 0953-8585
Wan L, Wade J, Wang X, et al., 2022, Engineering the sign of circularly polarized emission in achiral polymer – chiral small molecule blends as a function of blend ratio, Journal of Materials Chemistry C, Vol: 10, Pages: 5168-5172, ISSN: 2050-7526
Circularly polarized organic light-emitting diodes (CP-OLEDs) that demonstrate both state-of-the-art efficiency and strongly circularly polarized (CP) electroluminescence have proved a considerable technical challenge. Furthermore, multiple factors – from film thickness to device structure – have been shown to influence the sign of the emitted CP light, independent of the handedness (absolute stereochemistry) of the chiral emitter. Here we report CP-OLEDs using a blend of poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) and a chiral small molecule additive (1-azahelicene, azaH). We demonstrate CP-OLEDs with an impressive electroluminescence dissymmetry (gEL) > 0.3 and a current efficiency of 0.53 cd A−1 and brightness of 3023 cd m−2. While at low azaH loadings, F8T2 blends are consistent with previous observations of CP dissymetric inversion as a function of film thickness/excitation mode, a higher loading of azaH (∼40 wt%) removes such dependencies while retaining excellent g-factors. The materials disclosed will allow for further mechanistic studies of chiral polymeric materials and provide new opportunities for chiroptical optimisation in films and devices.
Ward MD, Wade J, Shi X, et al., 2022, Highly selective high-speed circularly polarized photodiodes based on π-conjugated polymers, Advanced Optical Materials, Vol: 10, ISSN: 2195-1071
Chiral π-conjugated molecular systems that are intrinsically sensitive to the handedness of circularly polarized (CP) light potentially allow for miniaturized, low-cost CP detection devices. Such devices promise to transform several technologies, including biosensing, quantum optics, and communication of data encrypted by exploiting the spin angular momentum of light. Here a simple, bilayer organic photodiode (CP OPD) comprising an achiral π-conjugated polymer–chiral additive blend as the electron donor layer and an achiral C60 electron acceptor layer is realized. These devices exhibit considerable photocurrent dissymmetry gph, with absolute values as high as 0.85 and dark currents as low as 10 pA. Impressively, they showcase a linear dynamic range of 80 dB, and rise and fall times of ≈7 µs, which significantly outperforms all previously reported CP selective photodetectors. Mechanistically, it is shown that the gph is sensitive to the thickness of both the chiral donor and achiral acceptor layers and that a trade-off exists between the external quantum efficiency and gph. The fast-switching speeds of these devices, coupled with their large dynamic range and highly selective response to CP light, opens up the possibility of their direct application in CP sensing and optical communications.
Wade J, 2021, Sticky: the Secret Science of Surfaces, PHYSICS WORLD, Vol: 34, Pages: 48-49, ISSN: 0953-8585
Laidlaw B, Eng J, Wade J, et al., 2021, On the factors influencing the chiroptical response of conjugated polymer thin films, Chemical Communications, Vol: 57, Pages: 9914-9917, ISSN: 1359-7345
We study the influence of the physical and chemical structure on the chiroptical response of fluorene-based polymeric systems, namely poly(9,9-dioctylfluorene) (PFO) and the donor–acceptor type copolymer poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT). We reveal the significance of electric-magnetic coupling, at both short (molecular-level) and intermediate (delocalised over multiple polymer chains) length scales, on the magnitude of the dissymmetry. These findings provide a framework for the design of new materials with enhanced chiroptical response.
Greenfield JL, Wade J, Brandt JR, et al., 2021, Pathways to increase the dissymmetry in the interaction of chiral light and chiral molecules, Chemical Science, Vol: 12, Pages: 8589-8602, ISSN: 2041-6520
The dissymmetric interaction between circularly polarised (CP) light and chiral molecules is central to a range of areas, from spectroscopy and imaging to next-generation photonic devices. However, the selectivity in absorption or emission of left-handed versus right-handed CP light is low for many molecular systems. In this perspective, we assess the magnitude of the measured chiroptical response for a variety of chiral systems, ranging from small molecules to large supramolecular assemblies, and highlight the challenges towards enhancing chiroptical activity. We explain the origins of low CP dissymmetry and showcase recent examples in which molecular design, and the modification of light itself, enable larger responses. Our discussion spans spatial extension of the chiral chromophore, manipulation of transition dipole moments, exploitation of forbidden transitions and creation of macroscopic chiral structures; all of which can increase the dissymmetry. Whilst the specific strategy taken to enhance the dissymmetric interaction will depend on the application of interest, these approaches offer hope for the development and advancement of all research fields that involve interactions of chiral molecules and light.
Wan L, Shi X, Wade J, et al., 2021, Strongly Circularly Polarized Crystalline and β-Phase Emission from Poly(9,9-dioctylfluorene)-Based Deep-Blue Light-Emitting Diodes, Advanced Optical Materials, Vol: 9, ISSN: 2195-1071
A key challenge in the realization of circularly polarized polymer light-emitting diodes (CP-PLEDs) is the generation of highly circularly polarized deep-blue electroluminescence (EL). Here, by blending the achiral luminescent polymer poly(9,9-dioctylfluorene) (PFO) with a helically chiral molecule 1-azahelicene the authors present CP-PLEDs with state-of-the-art device performance for deep-blue CP emission: for an inverted device with a semicrystalline microstructure a current efficiency (CE) of 1.13 cd A−1, a power efficiency (PE) of 0.81 lm W−1, and an EL dissymmetry (gEL) of −0.42 are achieved; for the planarized and extended “β-phase” chain conformation a CE of 1.23 cd A−1, a PE of 0.63 lm W−1, and a gEL of −0.44 are achieved. While these two phases achieve both high CE, as well as gEL, the latter affords the first demonstration of chiral β-phase emission from solid-state PFO devices. Such strongly circularly polarized light is generated from a supramolecular assembly of interacting planar polymer backbones. The authors rationalize that the strong chiroptical effects observed within such chiral β-phase PFO domains originate from coupled interchain aggregates. The findings not only demonstrate efficient deep-blue CP-PLEDs, but also provide insight into the mechanisms that underpin the strong CP emission from excitonically coupled polymer chains.
Wade J, Higgins SG, Heutz S, et al., 2021, In memoriam Alasdair James Campbell (11 May 1961-27 February 2021), Journal of Materials Chemistry C, Vol: 9, Pages: 6100-6102, ISSN: 2050-7526
Razzell Hollis J, Fornaro T, Rapin W, et al., 2021, Detection and Degradation of Adenosine Monophosphate in Perchlorate-Spiked Martian Regolith Analogue, by Deep-Ultraviolet Spectroscopy, ASTROBIOLOGY, Vol: 21, Pages: 511-525, ISSN: 1531-1074
Ball P, Britton TB, Hengel E, et al., 2021, Gender issues in fundamental physics: Strumia’s bibliometric analysis fails to account for key confounders and confuses correlation with causation, Quantitative Science Studies, Vol: 2, Pages: 263-272
Shi W, Salerno F, Ward MD, et al., 2021, Fullerene desymmetrization as a means to achieve single-enantiomer electron acceptors with maximized chiroptical responsiveness., Advanced Materials, Vol: 33, Pages: 1-7, ISSN: 0935-9648
Solubilized fullerene derivatives have revolutionized the development of organic photovoltaic devices, acting as excellent electron acceptors. The addition of solubilizing addends to the fullerene cage results in a large number of isomers, which are generally employed as isomeric mixtures. Moreover, a significant number of these isomers are chiral, which further adds to the isomeric complexity. The opportunities presented by single-isomer, and particularly single-enantiomer, fullerenes in organic electronic materials and devices are poorly understood however. Here, ten pairs of enantiomers are separated from the 19 structural isomers of bisphenyl-C61-butyric acid methyl ester, using them to elucidate important chiroptical relationships and demonstrating their application to a circularly polarized light (CPL)-detecting device. Larger chiroptical responses are found, occurring through the inherent chirality of the fullerene. When used in a single-enantiomer organic field-effect transistor, the potential to discriminate CPL with a fast light response time and with a very high photocurrent dissymmetry factor (gph = 1.27 ± 0.06) is demonstrated. This study thus provides key strategies to design fullerenes with large chiroptical responses for use as chiral components of organic electronic devices. It is anticipated that this data will position chiral fullerenes as an exciting material class for the growing field of chiral electronic technologies.
Wade J, Brandt JR, Reger D, et al., 2021, 500‐Fold Amplification of Small Molecule Circularly Polarised Luminescence through Circularly Polarised FRET, Angewandte Chemie, Vol: 133, Pages: 224-229, ISSN: 0044-8249
<jats:title>Abstract</jats:title><jats:p>Strongly dissymmetric circularly polarised (CP) luminescence from small organic molecules could transform a range of technologies, such as display devices. However, highly dissymmetric emission is usually not possible with small organic molecules, which typically give dissymmetric factors of photoluminescence (<jats:italic>g</jats:italic><jats:sub>PL</jats:sub>) less than 10<jats:sup>−2</jats:sup>. Here we describe an almost 10<jats:sup>3</jats:sup>‐fold chiroptical amplification of a π‐extended superhelicene when embedded in an achiral conjugated polymer matrix. This combination increases the |<jats:italic>g</jats:italic><jats:sub>PL</jats:sub>| of the superhelicene from approximately 3×10<jats:sup>−4</jats:sup> in solution to 0.15 in a blend film in the solid‐state. We propose that the amplification arises not simply through a chiral environment effect, but instead due to electrodynamic coupling between the electric and magnetic transition dipoles of the polymer donor and superhelicene acceptor, and subsequent CP Förster resonance energy transfer. We show that this amplification effect holds across several achiral polymer hosts and thus represents a simple and versatile approach to enhance the g‐factors of small organic molecules.</jats:p>
Ball P, Hengel E, Moriarty P, et al., 2021, Gender issues in fundamental physics: Strumia's bibliometric analysis fails to account for key confounders and confuses correlation with causation, Quantitative Science Studies, Vol: 2, Pages: 1-10, ISSN: 2641-3337
Alessandro Strumia recently published a survey of gender differences in publications and citations in high-energy physics (HEP). In addition to providing full access to the data, code, and methodology, Strumia (2020) systematically describes and accounts for gender differences in HEP citation networks. His analysis points both to ongoing difficulties in attracting women to high-energy physics and an encouraging—though slow—trend in improvement.
Wade J, 2021, Sticky: the Secret Science of Surfaces, PHYSICS WORLD, Vol: 34, Pages: 48-49, ISSN: 0953-8585
Wade J, Hilfiker J, Brandt J, et al., 2020, Natural optical activity as the origin of the large chiroptical properties in π-conjugated polymer thin films, Nature Communications, Vol: 11, ISSN: 2041-1723
Polymer thin films that emit and absorb circularly polarised light have been demonstrated with the promise of achieving important technological advances; from efficient, high-performance displays, to 3D imaging and all-organic spintronic devices. However, the origin of the large chiroptical effects in such films has, until now, remained elusive. We investigate the emergence of such phenomena in achiral polymers blended with a chiral small-molecule additive (1-azahelicene) and intrinsically chiral-sidechain polymers using a combination of spectroscopic methods and structural probes. We show that – under conditions relevant for device fabrication – the large chiroptical effects are caused by magneto-electric coupling (natural optical activity), not structural chirality as previously assumed, and may occur because of local order in a cylinder blue phase-type organisation. This disruptive mechanistic insight into chiral polymer thin films will offer new approaches towards chiroptical materials development after almost three decades of research in this area.
Wade J, 2020, Making a difference where it matters, PHYSICS WORLD, Vol: 33, Pages: 20-20, ISSN: 0953-8585
Wade J, Brandt J, Reger D, et al., 2020, 500‐fold amplification of small molecule circularly polarized luminescence through circularly polarized FRET, Angewandte Chemie International Edition, ISSN: 1433-7851
Strongly dissymmetric circularly polarised (CP) luminescence from small organic molecules could transform a range of technologies, such as display devices. However, highly dissymmetric emission is usually not possible with small organic molecules, which typically give dissymmetric factors of photoluminescence ( g PL ) less than 10 ‐2 . Here we describe an almost 10 3 ‐fold chiroptical amplification of a π‐extended superhelicene when embedded in an achiral conjugated polymer matrix. This combination increases the |gPL| of the superhelicene from approximately 3 × 10 ‐4 in solution to 0.15 in a blend film in the solid‐state. We propose that the amplification arises not simply through a chiral environment effect, but instead due to electrodynamic coupling between the electric and magnetic transition dipoles of the polymer donor and superhelicene acceptor, and subsequent CP Förster resonance energy transfer. We show that this amplification effect holds across several achiral polymer hosts and thus represents a simple and versatile approach to enhance the g‐factors of small organic molecules.
Armstrong ES, Persaud DM, Jackson CA-L, et al., 2020, Redefining the scientific conference, PHYSICS WORLD, Vol: 33, Pages: 21-21, ISSN: 0953-8585
Wan L, Wade J, Shi X, et al., 2020, Highly Efficient Inverted Circularly Polarized Organic Light-Emitting Diodes, ACS Applied Materials & Interfaces, Vol: 12, Pages: 39471-39478, ISSN: 1944-8244
Circularly polarized (CP) electroluminescence has been demonstrated as a strategy to improve the performance of organic light-emitting diode (OLED) displays. CP emission can be generated from both small-molecule and polymer OLEDs (SM-OLEDs and PLEDs), but to date, these devices suffer from low dissymmetry factors (g-factor < 0.1), poor device performance, or a combination of the two. Here, we demonstrate the first CP-PLED employing an inverted device architecture. Through this approach, we demonstrate a highly efficient CP-PLED, with a current efficiency of 16.4 cd/A, a power efficiency of 16.6 lm/W, a maximum luminance of over 28,500 cd/m2, and a high EL dissymmetry (gEL) of 0.57. We find that the handedness of the emitted light is sensitive to the PLED device architecture: the sign of CP-EL from an identically prepared active layer reverses between inverted and conventional devices. The inverted structure affords the first demonstration of CP-PLEDs exhibiting both high efficiency and high dissymmetry—the two figures of merit which, until now, have been difficult to achieve at the same time. We also highlight device architecture and associated internal electric field to be a previously unexplored means to control the handedness of CP emission. Our findings significantly broaden the versatility of CP emissive devices and should enable their further application in a variety of other CP-dependent technologies.
Rajan G, Morgan JJ, Murphy C, et al., 2020, Low Operating Voltage Carbon-Graphene Hybrid E-textile for Temperature Sensing, ACS APPLIED MATERIALS & INTERFACES, Vol: 12, Pages: 29861-29867, ISSN: 1944-8244
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