54 results found
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
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
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
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
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, 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
Wade J, 2020, Preface for the Women's perspectives in 2D materials focus issue, JOURNAL OF PHYSICS-MATERIALS, Vol: 3
Wade J, 2020, Radioactive, PHYSICS WORLD, Vol: 33, Pages: 50-51, ISSN: 0953-8585
Karim MMS, Ganose AM, Pieters L, et al., 2019, Anion Distribution, Structural Distortion, and Symmetry-Driven Optical Band Gap Bowing in Mixed Halide Cs2SnX6 Vacancy Ordered Double Perovskites, CHEMISTRY OF MATERIALS, Vol: 31, Pages: 9430-9444, ISSN: 0897-4756
Wade J, Radcliffe D, 2019, Tricks and wizardry, PHYSICS WORLD, Vol: 32, Pages: 35-36, ISSN: 0953-8585
Yan H, Limbu S, Wang X, et al., 2019, Efficient charge carrier injection and balance achieved by low electrochemical doping in solution-processed polymer light-emitting diodes, Advanced Functional Materials, Vol: 29, Pages: 1-9, ISSN: 1616-301X
Charge carrier injection and transport in polymer light‐emitting diodes (PLEDs) is strongly limited by the energy level offset at organic/(in)organic interfaces and the mismatch in electron and hole mobilities. Herein, these limitations are overcome via electrochemical doping of a light‐emitting polymer. Less than 1 wt% of doping agent is enough to effectively tune charge injection and balance and hence significantly improve PLED performance. For thick single‐layer (1.2 µm) PLEDs, dramatic reductions in current and luminance turn‐on voltages (VJ = 11.6 V from 20.0 V and VL = 12.7 V from 19.8 V with/without doping) accompanied by reduced efficiency roll‐off are observed. For thinner (<100 nm) PLEDs, electrochemical doping removes a thickness dependence on VJ and VL, enabling homogeneous electroluminescence emission in large‐area doped devices. Such efficient charge injection and balance properties achieved in doped PLEDs are attributed to a strong electrochemical interaction between the polymer and the doping agents, which is probed by in situ electric‐field‐dependent Raman spectroscopy combined with further electrical and energetic analysis. This approach to control charge injection and balance in solution‐processed PLEDs by low electrochemical doping provides a simple yet feasible strategy for developing high‐quality and efficient lighting applications that are fully compatible with printing technologies.
Wade J, Pugh H, Nightingale J, et al., 2019, Colour in bivalve shells: Using resonance Raman spectroscopy to compare pigments at different phylogenetic levels, Journal of Raman Spectroscopy, Vol: 50, Pages: 1527-1536, ISSN: 0377-0486
Several studies have suggested that shell colour may be phylogenetically distributed within the phylum Mollusca, but this pattern is confounded by our ignorance of the homology of colour and lack of understanding about the identity of most molluscan pigments. We use resonance Raman spectroscopy to address this problem by examining bivalve pigments producing a range of colours and compare spectra from taxa at different phylogenetic levels. The spectra of most shell pigments exhibited a skeletal signature typical of partially methylated polyenes, possibly modified carotenoids, with the strongest peaks occurring between 1,501–1,540 cm−1 and 1,117–1,144 cm−1 due to the C═C (ν1) and C–C (ν2) stretching modes, respectively. Neither pigment class nor mineral structure differentiated Imparidentia and Pteriomorphia. Spectral acquisitions for purple pigments for two species of Asaphis suggest that identical or nearly identical pigments are shared within this genus, and some red pigments from distantly related species have similar spectra. Conversely, two species with brown shells have distinctly different pigments, highlighting the difficulty in determining the homology of colour even within a single class of pigments. Curiously, we were unable to detect any Raman activity for green‐coloured shell or pigment peaks for the yellow area of Codakia paytenorum, suggesting that these colours are due to structural elements or a pigment that is quite different from those observed in other taxa examined to date. Our results are consistent with the idea that classes of pigments are evolutionarily ancient but heritable modifications may be specific to clades.
Britton B, Jackson C, Wade J, 2019, The reward and risk of social media for academics, Nature Reviews Chemistry, Vol: 3, Pages: 459-461, ISSN: 2397-3358
We are three academics who are active on social media. We explore the motivations for and benefits of engaging with social media, as well as its costs and risks. Overall, we believe this engagement to be a net benefit for us, our employers and for wider society.
Wade J, Zaringhalam M, 2019, Why we need to keep talking about equality in physics, PHYSICS WORLD, Vol: 32, Pages: 34-38, ISSN: 0953-8585
Wan L, Wade J, Salerno F, et al., 2019, Inverting the handedness of circularly polarized luminescence from light-emitting polymers using film thickness, ACS Nano, Vol: 13, Pages: 8099-8105, ISSN: 1936-0851
The emission of circularly polarized light is central to many applications, including data storage, optical quantum computation, biosensing, environmental monitoring, and display technologies. An emerging method to induce (chiral) circularly polarized (CP) electroluminescence from the active layer of polymer light-emitting diodes (polymer OLEDs; PLEDs) involves blending achiral polymers with chiral small-molecule additives, where the handedness/sign of the CP light is controlled by the absolute stereochemistry of the small molecule. Through the in-depth study of such a system we report an interesting chiroptical property: the ability to tune the sign of CP light as a function of active layer thickness for a fixed enantiomer of the chiral additive. We demonstrate that it is possible to achieve both efficient (4.0 cd/A) and bright (8000 cd/m2) CP-PLEDs, with high dissymmetry of emission of both left-handed (LH) and right-handed (RH) light, depending on thickness (thin films, 110 nm: gEL = 0.51, thick films, 160 nm: gEL = -1.05, with the terms "thick" and "thin" representing the upper and lower limits of the thickness regime studied), for the same additive enantiomer. We propose that this arises due to an interplay between localized CP emission originating from molecular chirality and CP light amplification or inversion through a chiral medium. We link morphological, spectroscopic, and electronic characterization in thin films and devices with theoretical studies in an effort to determine the factors that underpin these observations. Through the control of active layer thickness and device architecture, this study provides insights into the mechanisms that result in CP luminescence and high performance from CP-PLEDs, as well as demonstrating new opportunities in CP photonic device design.
Wade J, 2019, 30 years of the Web, PHYSICS WORLD, Vol: 32, Pages: 38-38, ISSN: 0953-8585
Wade J, 2019, Let's fight sexism with data, NEW SCIENTIST, Vol: 241, Pages: 24-25, ISSN: 0262-4079
Gabrys BJ, Wade J, Dyer J, et al., 2019, Women in Physics in the UK: On the Road to Equality, 6th IUPAP International Conference on Women in Physics (ICWIP), Publisher: AMER INST PHYSICS, ISSN: 0094-243X
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