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  • Journal article
    Eames C, Frost JM, Barnes PRF, O'Regan BC, Walsh A, Islam MSet al., 2015,

    Ionic transport in hybrid lead iodide perovskite solar cells

    , NATURE COMMUNICATIONS, Vol: 6, ISSN: 2041-1723
  • Journal article
    Leguy AMA, Frost JM, McMahon AP, Sakai VG, Kochelmann W, Law C, Li X, Foglia F, Walsh A, O'Regan BC, Nelson J, Cabral JT, Barnes PRFet al., 2015,

    The dynamics of methylammonium ions in hybrid organic-inorganic perovskite solar cells

    , Nature Communications, Vol: 6, ISSN: 2041-1723

    Methylammonium lead iodide perovskite can make high-efficiency solar cells, which also show an unexplained photocurrent hysteresis dependent on the device-poling history. Here we report quasielastic neutron scattering measurements showing that dipolar CH3NH3+ ions reorientate between the faces, corners or edges of the pseudo-cubic lattice cages in CH3NH3PbI3 crystals with a room temperature residence time of ~14 ps. Free rotation, π-flips and ionic diffusion are ruled out within a 1–200-ps time window. Monte Carlo simulations of interacting CH3NH3+ dipoles realigning within a 3D lattice suggest that the scattering measurements may be explained by the stabilization of CH3NH3+ in either antiferroelectric or ferroelectric domains. Collective realignment of CH3NH3+ to screen a device’s built-in potential could reduce photovoltaic performance. However, we estimate the timescale for a domain wall to traverse a typical device to be ~0.1–1 ms, faster than most observed hysteresis.

  • Journal article
    Leguy AMA, Hu Y, Campoy-Quiles M, Isabel Alonso M, Weber OJ, Azarhoosh P, van Schilfgaarde M, Weller MT, Bein T, Nelson J, Docampo P, Barnes PRFet al., 2015,

    Reversible Hydration of CH(3)NH(3)Pbl(3) in Films, Single Crystals, and Solar Cells

    , CHEMISTRY OF MATERIALS, Vol: 27, Pages: 3397-3407, ISSN: 0897-4756
  • Journal article
    Gilbertson AM, Francescato Y, Roschuk T, Shautsova V, Chen Y, Sidiropoulos TPH, Hong M, Giannini V, Maier SA, Cohen LF, Oulton RFet al., 2015,

    Plasmon-Induced Optical Anisotropy in Hybrid Graphene-Metal Nanoparticle Systems

    , NANO LETTERS, Vol: 15, Pages: 3458-3464, ISSN: 1530-6984
  • Journal article
    O'Regan BC, Barnes PRF, Li X, Law C, Palomares E, Marin-Beloqui JMet al., 2015,

    Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO2: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J-V Hysteresis

    , JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 137, Pages: 5087-5099, ISSN: 0002-7863
  • Journal article
    Okell WA, Witting T, Fabris D, Arrell CA, Hengster J, Ibrahimkutty S, Seiler A, Barthelmess M, Stankov S, Lei DY, Sonnefraud Y, Rahmani M, Uphues T, Maier SA, Marangos JP, Tisch JWGet al., 2015,

    Temporal broadening of attosecond photoelectron wavepackets from solid surfaces

    , Optica, Vol: 2, Pages: 383-387, ISSN: 2334-2536
  • Journal article
    Liao Z, Luo Y, Fernández-Domínguez AI, Shen X, Maier SA, Cui TJet al., 2015,

    High-order localized spoof surface plasmon resonances and experimental verifications.

    , Scientific Reports, Vol: 5, ISSN: 2045-2322

    We theoretically demonstrated and experimentally verified high-order radial spoof localized surface plasmon resonances supported by textured metal particles. Through an effective medium theory and exact numerical simulations, we show the emergence of these geometrically-originated electromagnetic modes at microwave frequencies. The occurrence of high-order radial spoof plasmon resonances is experimentally verified in ultrathin disks. Their spectral and near-field properties are characterized experimentally, showing an excellent agreement with theoretical predictions. Our findings shed light into the nature of spoof localized surface plasmons, and open the way to the design of broadband plasmonic devices able to operate at very different frequency regimes.

  • Journal article
    Caldwell JD, Lindsay L, Giannini V, Vurgaftman I, Reinecke TL, Maier SA, Glembocki OJet al., 2015,

    Low-loss, infrared and terahertz nanophotonics using surface phonon polaritons

    , Nanophotonics, Vol: 4, Pages: 44-68, ISSN: 2192-8614

    The excitation of surface-phonon-polariton (SPhP) modes in polar dielectric crystals and the associated new developments in the field of SPhPs are reviewed. The emphasis of this work is on providing an understanding of the general phenomenon, including the origin of the Reststrahlen band, the role that optical phonons in polar dielectric lattices play in supporting sub-diffraction-limited modes and how the relatively long optical phonon lifetimes can lead to the low optical losses observed within these materials. Based on this overview, the achievements attained to date and the potential technological advantages of these materials are discussed for localized modes in nanostructures, propagating modes on surfaces and in waveguides and novel metamaterial designs, with the goal of realizing low-loss nanophotonics and metamaterials in the mid-infrared to terahertz spectral ranges.

  • Journal article
    Braic L, Vasilantonakis N, Zou B, Maier SA, Alford NM, Zayats AV, Petrov PKet al., 2015,

    Optimizing strontium ruthenate thin films for near-infrared plasmonic applications

    , Scientific Reports, Vol: 5, ISSN: 2045-2322

    Several new plasmonic materials have recently been introduced in order to achieve better temperature stability than conventional plasmonic metals and control field localization with a choice of plasma frequencies in a wide spectral range. Here, epitaxial SrRuO3 thin films with low surface roughness fabricated by pulsed laser deposition are studied. The influence of the oxygen deposition pressure (20–300 mTorr) on the charge carrier dynamics and optical constants of the thin films in the near-infrared spectral range is elucidated. It is demonstrated that SrRuO3 thin films exhibit plasmonic behavior of the thin films in the near-infrared spectral range with the plasma frequency in 3.16–3.86 eV range and epsilon-near-zero wavelength in 1.11–1.47 μm range that could be controlled by the deposition conditions. The possible applications of these films range from the heat-generating nanostructures in the near-infrared spectral range, to metamaterial-based ideal absorbers and epsilon-near-zero components, where the interplay between real and imaginary parts of the permittivity in a given spectral range is needed for optimizing the spectral performance.

  • Journal article
    Chen Y, Li X, Sonnefraud Y, Fernandez-Dominguez AI, Luo X, Hong M, Maier SAet al., 2015,

    Engineering the Phase Front of Light with Phase-Change Material Based Planar lenses

    , SCIENTIFIC REPORTS, Vol: 5, ISSN: 2045-2322

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