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  • 1.
    Carrara, Angelica
    et al.
    Istituto Italiano di Tecnologia, Genova, Italy.
    Maccaferri, Nicolò
    Istituto Italiano di Tecnologia, Genova, Italy; Department of Physics and Materials Science, University of Luxembourg, Luxembourg, Luxembourg.
    Cerea, Andrea
    Istituto Italiano di Tecnologia, Genova, Italy.
    Bozzola, Angelo
    Istituto Italiano di Tecnologia, Genova, Italy.
    De Angelis, Francesco
    Istituto Italiano di Tecnologia, Genova, Italy.
    Proietti Zaccaria, Remo
    Istituto Italiano di Tecnologia, Genova, Italy; Cixi Institute of Biomedical Engineering, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, China.
    Toma, Andrea
    Istituto Italiano di Tecnologia, Genova, Italy.
    Plasmon Hybridization in Compressible Metal–Insulator–Metal Nanocavities: An Optical Approach for Sensing Deep Sub‐Wavelength Deformation2020Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 8, nr 18, artikel-id 2000609Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A pressure-induced deformation-sensitive device (DSD) is presented based on 2D matrices of plasmonic gold nanodisks coupled to a metal thin layer through a compressible dielectric spacer, namely a deformable metal–insulator–metal (MIM) nanocavity, to report deep sub-wavelength size variations (<λ/200). The system is characterized by two hybrid branches, which are resonant in the visible/near infrared spectral region. The fundamental mode, owing to the near-field interaction between the plasmonic nanostructures and the metal film, exhibits a remarkable sensitivity to the gap size, exceeding that of a planar “macroscopic” optical cavity and extending its operational domain to the sub-wavelength range, where excellent opportunities toward truly multiscale MIMs-based pressure sensors can be envisioned. Concurrently, its intrinsic plasmonic nature synergistically combines into a single platform multi-purpose functionalities, such as ultrasensitive detection and remote temperature readout, with practical perspectives in ultra-compact inspection tools for structural and functional information at the nanoscale.

  • 2.
    Giovannini, Giorgia
    et al.
    Istituto Italiano di Tecnologia via Morego 30 I‐16163 Genova Italy.
    Ardini, Matteo
    Istituto Italiano di Tecnologia via Morego 30 I‐16163 Genova Italy;Department of Life, Health and Environmental SciencesUniversity of L'Aquila Via Vetoio snc, Coppito CAP 67100 L'Aquila Italy.
    Maccaferri, Nicolò
    Istituto Italiano di Tecnologia via Morego 30 I‐16163 Genova Italy;Department of Physics and Material ScienceUniversity of Luxembourg 162a avenue de la Faïencerie L‐1511 Luxembourg Luxembourg.
    Zambrana‐Puyalto, Xavier
    Istituto Italiano di Tecnologia via Morego 30 I‐16163 Genova Italy.
    Panella, Gloria
    Department of Life, Health and Environmental SciencesUniversity of L'Aquila Via Vetoio snc, Coppito CAP 67100 L'Aquila Italy.
    Angelucci, Francesco
    Department of Life, Health and Environmental SciencesUniversity of L'Aquila Via Vetoio snc, Coppito CAP 67100 L'Aquila Italy.
    Ippoliti, Rodolfo
    Department of Life, Health and Environmental SciencesUniversity of L'Aquila Via Vetoio snc, Coppito CAP 67100 L'Aquila Italy.
    Garoli, Denis
    Istituto Italiano di Tecnologia via Morego 30 I‐16163 Genova Italy.
    De Angelis, Francesco
    Istituto Italiano di Tecnologia via Morego 30 I‐16163 Genova Italy.
    Bio‐Assisted Tailored Synthesis of Plasmonic Silver Nanorings and Site‐Selective Deposition on Graphene Arrays2020Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 8, nr 4, s. 1901583-1901583Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The spontaneous interaction between noble metals and biological scaffolds enables simple and cost-effective synthesis of nanomaterials with unique features. Here, plasmonic silver nanorings are synthesized on a ring-like protein, i.e., a peroxiredoxin (PRX), and used to assemble large arrays of functional nanostructures. The PRX drives the seeding growth of metal silver under wet reducing conditions, yielding nanorings with outer and inner diameters down to 28 and 3 nm, respectively. The obtained hybrid nanostructures are selectively deposited onto a solid-state 2D membrane made of graphene in order to prepare plasmonic nanopores. In particular, the interaction between the graphene and the PRX allows for the simple preparation of ordered arrays of plasmonic nanorings on a 2D-material membrane. This fabrication process can be finalized by drilling a nanometer scale pore in the middle of the ring. Fluorescence spectroscopic measurements in combination with numerical simulations demonstrate the plasmonic effects induced in the metallic nanoring cavity. The prepared nanopores represent one of the first examples of hybrid plasmonic nanopore structures integrated on a 2D-material membrane. The diameter of the nanopore and the atomically thick substrate make this proof-of-concept approach particularly interesting for nanopore-based technologies and applications such as next-generation sequencing and single-molecule detection.

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  • 3.
    Isoniemi, Tommi
    et al.
    Istituto Italiano di Tecnologia Via Morego 30 Genova 16163 Italy;Department of Physics and AstronomyUniversity of Sheffield Sheffield S3 7RH UK.
    Maccaferri, Nicolò
    Istituto Italiano di Tecnologia Via Morego 30 Genova 16163 Italy;Department of Physics and Materials ScienceUniversity of Luxembourg 162a avenue de la Faïencerie Luxembourg L‐1511 Luxembourg.
    Ramasse, Quentin M.
    SuperSTEM LaboratorySciTech Daresbury CampusKeckwick Lane Daresbury WA4 4AD UK;School of PhysicsUniversity of Leeds Leeds LS2 9JT UK;School of Chemical and Process EngineeringUniversity of Leeds Leeds LS2 9JT UK.
    Strangi, Giuseppe
    Department of PhysicsCase Western Reserve University 10600 Euclid Avenue Cleveland OH 44106 USA;CNR‐NANOTEC Istituto di Nanotecnologia and Department of PhysicsUniversity of Calabria Rende 87036 Italy.
    De Angelis, Francesco
    Istituto Italiano di Tecnologia Via Morego 30 Genova 16163 Italy.
    Electron Energy Loss Spectroscopy of Bright and Dark Modes in Hyperbolic Metamaterial Nanostructures2020Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 8, nr 13, artikel-id 2000277Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Layered metal/dielectric hyperbolic metamaterials (HMMs) support a wide landscape of plasmon polariton excitations. In addition to surface plasmon polaritons, coupled Bloch-like gap-plasmon polaritons with high modal confinement inside the multilayer are supported. Photons can excite only a subset of these polaritonic modes, typically with a limited energy and momentum range in respect to the wide set of high-K modes supported by hyperbolic dispersion media, and coupling with gratings or local excitation is necessary. Strikingly, electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope allows nm-scale local excitation and mapping of the spatial field distribution of all the modes supported by a photonic or plasmonic structure, both bright and dark, and also all other inelastic interactions of the beam, including phonons and interband transitions. Herein, experimental evidence of the spatial distribution of plasmon polaritons in multilayered type II HMM nanostructures is acquired with an aloof electron beam adjacent to structures of current interest. HMM pillars are useful for their separation and adjustability of optical scattering and absorption, while HMM slot cavities can be used as waveguides with high field confinement. The nature of the modes is confirmed with corresponding simulations of EEL and optical spectra and near-field intensities.

  • 4.
    Lanzavecchia, German
    et al.
    Optoelectronics Group, Istituto Italiano di Tecnologia, Genova, Italy; Dipartimento di Fisica, Univesità di Genova, Genova, Italy.
    Kuttruff, Joel
    Department of Physics, Universität Konstanz, Konstanz, Germany.
    Doricchi, Andrea
    Optoelectronics Group, Istituto Italiano di Tecnologia, Genova, Italy; Dipartimento di Chimica, Univesità di Genova, Genova, Italy.
    Douaki, Ali
    Optoelectronics Group, Istituto Italiano di Tecnologia, Genova, Italy.
    Kumaranchira Ramankutty, Krishnadas
    CIC biomaGUNE, Basque Research and Technology Alliance (BRTA), Donostia-San Sebastián, Spain.
    García, Isabel
    CIC biomaGUNE, Basque Research and Technology Alliance (BRTA), Donostia-San Sebastián, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN), Donostia-San Sebastián, Spain.
    Lin, Lyuye
    Optoelectronics Group, Istituto Italiano di Tecnologia, Genova, Italy.
    Viejo Rodríguez, Alba
    Department of Physics and Materials Science, University of Luxembourg, Luxembourg, Luxembourg.
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Krahne, Roman
    Optoelectronics Group, Istituto Italiano di Tecnologia, Genova, Italy.
    Maccaferri, Nicolò
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). Department of Physics and Materials Science, University of Luxembourg, Luxembourg, Luxembourg.
    Garoli, Denis
    Optoelectronics Group, Istituto Italiano di Tecnologia, Genova, Italy.
    Plasmonic photochemistry as a tool to prepare metallic nanopores with controlled diameter for optimized detection of single entities2023Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 11, nr 16, artikel-id 2300786Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plasmonic solid-state nanopores with tunable hole diameters can be prepared via a photocatalytic effect resulting from the enhanced electromagnetic (EM) field inside a metallic ring on top of a dielectric nanotube. Under white light illumination, the plasmon-enhanced EM-field induces a site-selective metal nucleation and growth within the ring. This approach is used to prepare Au and bimetallic Au–Ag nano-rings and demonstrate the reduction of the initial inner diameter of the nanopore down to 4 nm. The tunability of the nanopore diameter can be used to enable optimized detection of single entities with different sizes. As a proof-of-concept, single object detection of double stranded DNA (dsDNA) and Au nanoparticles (AuNPs) with a diameter down to 15 nm is performed. Numerical simulations provide insights into the EM-field distribution and confinement, showing that a field intensity enhancement of up to 104 can be achieved inside the nanopores. This localized EM-field can be used to perform enhanced optical measurements and generate local heating, thereby modifying the properties of the nanopore. Such a flexible approach also represents a valuable tool to investigate plasmon-driven photochemical reactions, and it can represent an important step toward the realization of new plasmonic devices.

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  • 5.
    Liu, Xianghui
    et al.
    State Key Lab of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China.
    Xiao, Chengyu
    State Key Lab of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China.
    Wang, Pan
    State Key Lab of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China.
    Yan, Max
    Department of Applied Physics School of Engineering Sciences KTH Royal Institute of Technology Stockholm 11419 Sweden.
    Wang, Huifen
    Shanghai Institute of Spacecraft Equipment Shanghai Academy of Spaceflight Technology Shanghai 200240 China.
    Xie, Peiwen
    State Key Lab of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China.
    Liu, Gang
    Shanghai Institute of Spacecraft Equipment Shanghai Academy of Spaceflight Technology Shanghai 200240 China.
    Zhou, Han
    State Key Lab of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China.
    Zhang, Di
    State Key Lab of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China.
    Fan, Tongxiang
    State Key Lab of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China.
    Biomimetic photonic multiform composite for high‐performance radiative cooling2021Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 9, nr 22, artikel-id 2101151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanostructures on bodies of biological inhabitants in severe environments can exhibit excellent thermoregulation, which provide inspirations for artificial radiative cooling materials. However, achieving both large-scale manufacturing and flexible form-compatibility to various applications needs remains as a formidable challenge. Here a biomimetic strategy is adopted to design a thermal photonic composite inspired by the previously unexplored golden cicada's evolutionarily optimized thermoregulatory ability. A microimprint combined with phase separation method is developed for fabricating a biomimetic photonic material made of porous polymer–ceramic composite profiled in microhumps. The composite demonstrates high solar reflectance (97.6%) and infrared emissivity (95.5%) in atmospheric window, which results in a cooling power of 78 W m−2 and a maximum subambient temperature drop of 6.6 °C at noon. Moreover, the technique facilitates multiform manufacturing of the composites beyond films, as demonstrated by additive printing into general 3D structures. This work offers biomimetic approach for developing high-performance thermal regulation materials and devices.

  • 6.
    Lobov, Gleb S.
    et al.
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Zhao, Yichen
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Marinins, Aleksandrs
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Yan, Min
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Li, Jiantong
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Sugunan, Abhilash
    Chemistry Materials and Surfaces Unit, SP Technical Research Institute of Sweden, Stockholm, Sweden.
    Thylén, Lars
    Hewlett‐Packard Laboratories, Palo Alto, USA; School of Biotechnology KTH, Royal Institute of Technology, Stockholm, Sweden.
    Wosinski, Lech
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Östling, Mikael
    School of Information and Communication Technology KTH Royal Institute of Technology Stockholm 16440 Sweden.
    Toprak, Muhammet S.
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Popov, Sergei
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Dynamic Manipulation of Optical Anisotropy of Suspended Poly‐3‐hexylthiophene Nanofibers2016Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 4, nr 10, s. 1651-1656Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline semiconducting nanostructures, which are known for their application in photovoltaics. Due to the internal arrangement, P3HT nanofibers possess optical anisotropy, which can be enhanced on a macroscale if nanofibers are aligned. Alternating electric field, applied to a solution with dispersed nanofibers, causes their alignment and serves as a method to produce solid layers with ordered nanofibers. The transmission ellipsometry measurements demonstrate the dichroic absorption and birefringence of ordered nanofibers in a wide spectral range of 400–1700 nm. Moreover, the length of nanofibers has a crucial impact on their degree of alignment. Using electric birefringence technique, it is shown that external electric field applied to the solution with P3HT nanofibers can cause direct birefringence modulation. Dynamic alignment of dispersed nanofibers changes the refractive index of the solution and, therefore, the polarization of transmitted light. A reversible reorientation of nanofibers is organized by using a quadrupole configuration of poling electrodes. With further development, the described method can be used in the area of active optical fiber components, lab-on-chip or sensors. It also reveals the potential of 1D conducting polymeric structures as objects whose highly anisotropic properties can be implemented in electro-optical applications.​

  • 7. Mone, Mariza
    et al.
    Tang, Shi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Genene, Zewdneh
    Murto, Petri
    Jevric, Martyn
    Zou, Xianshao
    Ràfols-Ribé, Joan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Abdulahi, Birhan A.
    Wang, Jia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Mammo, Wendimagegn
    Andersson, Mats R.
    Edman, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wang, Ergang
    Near-Infrared Emission by Tuned Aggregation of a Porphyrin Compound in a Host-Guest Light-Emitting Electrochemical Cell2021Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 9, nr 6, artikel-id 2001701Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The synthesis of 5,10,15,20-tetrakis((5,10-bis((2-hexyldecyl)oxy)dithieno[3,2-c:3′,2′-h][1,5]naphthyridin-2-yl)ethynyl)porphyrin zinc(II) (Por4NT), a near-infrared (NIR) emitting compound, comprising a zinc porphyrin core linked with triple bonds through its meso positions to four 5,10-bis((2-hexyldecyl)oxy)dithieno[3,2-c:3′,2′-h][1,5]naphthyridine (NT) arms is reported. Por4NT featured high solubility in common non-polar solvents, which is ideal for easy processing through solution techniques, and high photoluminescence (PL) efficiency of ≈30% in dilute toluene solution. It also exhibited a strong tendency for aggregation because of its flat conformation, and this aggregation resulted in a strong redshifted emission and a drop in PL efficiency. A well-matched PBDTSi-BDD-Py "host" terpolymer is therefore designed, which is capable of mitigating the aggregation of the Por4NT "guest". An optimized blend of the host, guest, and an ionic-liquid electrolyte is utilized as the active material in a light-emitting electrochemical cell (LEC), which delivered strong NIR radiance of 134 µW cm-2 with a long wavelength maximum at 810 nm at a low drive voltage of 5.0 V. The attainment of the strong NIR emission from the host–guest LEC is attributed to a tuned aggregation of the Por4NT emitter, which resulted in the desired aggregation-induced redshift of the emission at a reasonably retained efficiency.

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  • 8.
    Moradifar, Parivash
    et al.
    Department of Materials Science and Engineering, Materials Research Institute, The Pennsylvania State University, PA, University Park, United States.
    Nixon, Austin G.
    Department of Chemistry, University of Washington, WA, Seattle, United States.
    Sharifi, Tiva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Department of Materials Science and Nano Engineering, Rice University, TX, Houston, United States.
    van Driel, Tim Brandt
    SLAC National Accelerator Laboratory, CA, Menlo Park, United States.
    Ajayan, Pulickel
    Department of Materials Science and Nano Engineering, Rice University, TX, Houston, United States.
    Masiello, David J.
    Department of Chemistry, University of Washington, WA, Seattle, United States.
    Alem, Nasim
    Department of Materials Science and Engineering, Materials Research Institute, The Pennsylvania State University, PA, University Park, United States.
    Nanoscale Mapping and Defect-Assisted Manipulation of Surface Plasmon Resonances in 2D Bi2Te3/Sb2Te3 In-Plane Heterostructures2022Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 10, nr 10, artikel-id 2101968Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Bi2Te3/Sb2Te3 in-plane heterostructure is reported as a low-dimensional tunable chalcogenide well suited as plasmonic building block for the visible−UV spectral range. Electron-driven plasmon excitations of low-dimensional Bi2Te3/Sb2Te3 are investigated by monochromated electron energy loss spectroscopy spectrum imaging. To resolve the nanoscale spatial distribution of various local plasmonic resonances, singular value decomposition is used to disentangle the spectral data and identify the individual spectral contributions of various corner, edge, and face modes. Furthermore, defect-plasmon interactions are investigated both for nanoscale intrinsic and thermally induced extrinsic polygonal defects (in situ sublimation). Signature of defect-induced red shift ranging from a several hundreds of millielectronvolts to a few electronvolts, broadening of various plasmon response, together with selective enhancement and significant variations in their intensity are detected. This study highlights the presence of a heterointerface and identifies defects as physical tuning pathways to modulate the plasmonic response over a broad spectral range. Finally, the experimental observations are compared qualitatively and validated with numerical simulations using the electron-driven discrete dipole approximation. Low-dimensional Bi2Te3/Sb2Te3 as a less explored plasmonic system holds great promises as emerging platform for integrated plasmonics. Furthermore, introducing controlled structural defects can open the door for nanoengineering of plasmonic properties in such systems.

  • 9.
    Ràfols-Ribé, Joan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Gracia-Espino, Eduardo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Jenatsch, Sandra
    Lundberg, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Sandström, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Tang, Shi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Larsen, Christian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Edman, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Elucidating Deviating Temperature Behavior of Organic Light-Emitting Diodes and Light-Emitting Electrochemical Cells2021Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 9, nr 1, artikel-id 2001405Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Organic light-emitting diodes (OLEDs) and light-emitting electrochemical cells (LECs) exhibit different operational modes that render them attractive for complementary applications, but their dependency on the device temperature has not been systematically compared. Here, the effects of a carefully controlled device temperature on the performance of OLEDs and LECs based on two common emissive organic semiconductors are investigated. It is found that the peak luminance and current efficacy of the two OLEDs are relatively temperature independent, whereas, the corresponding LECs exhibit a significant increase by approximate to 85% when the temperature is changed from 20 to 80 degrees C. A combination of simulations and measurements reveal that this deviating behavior is consistent with a shift of the emission zone from closer to the transparent anode toward the center of the active material for both the OLEDs and the LECs, which in turn can be induced by a stronger positive temperature dependence of the mobility of the holes than the electrons.

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  • 10.
    Tang, Shi
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. LunaLEC AB, Umeå, Sweden.
    Larsen, Christian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. LunaLEC AB, Umeå, Sweden.
    Ràfols-Ribé, Joan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wang, Jia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Edman, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. LunaLEC AB, Umeå, Sweden.
    An Amorphous Spirobifluorene-Phosphine-Oxide Compound as the Balanced n-Type Host in Bright and Efficient Light-Emitting Electrochemical Cells with Improved Stability2021Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 9, nr 7, artikel-id 2002105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A rational host–guest concept design for the attainment of high efficiency at strong luminance from light‐emitting electrochemical cells (LECs) by suppression of exciton‐polaron quenching [Tang et al., Nature Communications 20178, 1190] has been reported. However, a practical drawback with the presented host–guest LEC devices was that the operational stability is insufficient for many applications. Here, a systematic study is performed, revealing that a major culprit for the limited operational stability is that the employed n‐type host, 1,3‐bis[2‐(4‐tert‐butylphenyl)‐1,3,4‐oxadiazo‐5‐yl]benzene (OXD‐7), has a strong propensity for crystallization and that this crystallization results in a detrimental phase separation of the constituents in the active material during device operation. The authors, therefore, identify an alternative class of concept‐functional n‐type hosts in the form of spirobifluorene‐phosphine‐oxide compounds, and report that the replacement of OXD‐7 with amorphous 2,7‐bis(diphenylphosphoryl)‐9,9′‐spirobifluorene results in a much improved operational lifetime of 700 h at >100 cd m−2 during constant‐bias driving at an essentially retained high current efficacy of 37.9 cd A−1 and a strong luminance of 2940 cd m−2.

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  • 11.
    Tang, Shi
    et al.
    The Organic Photonics and Electronics Group, Umeå University: LunaLEC AB, Umeå University, Umeå, Sweden Umeå, Sweden Umeå, Sweden.
    Murto, Petri
    Wang, Jia
    The Organic Photonics and Electronics Group, Umeå University, Umeå, Sweden.
    Larsen, Christian
    The Organic Photonics and Electronics Group, Umeå University; LunaLEC AB, Umeå University, Umeå, Sweden Umeå, Sweden Umeå, Sweden.
    Andersson, Mats R.
    Wang, Ergang
    Edman, Ludvig
    The Organic Photonics and Electronics Group, Umeå University; LunaLEC AB, Umeå University, Umeå, Sweden Umeå, Sweden.
    On the Design of Host-Guest Light-Emitting Electrochemical Cells: Should the Guest be Physically Blended or Chemically Incorporated into the Host for Efficient Emission?2019Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 7, nr 18, artikel-id 1900451Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It has recently been demonstrated that light-emitting electrochemical cells (LECs) can be designed to deliver strong emission with high efficiency when the charge transport is effectuated by a majority host and the emission is executed by a minority guest. A relevant question is then: should the guest be physically blended with or chemically incorporated into the host? A systematic study is presented that establishes that for near-infrared-(NIR-) emitting LECs based on poly(indacenodithieno[3,2-b]thiophene) (PIDTT) as the host and 4,7-bis(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b ']dithiophen-2-yl)benzo[c][1,2,5]-thiadiazole (SBS) as the guest the chemical-incorporation approach is preferable. The host-to-guest energy transfer in LEC devices is highly efficient at a low guest concentration of 0.5%, whereas guest aggregation and ion redistribution during device operation severly inhibits this transfer in the physical-blend devices. The chemical-incorporation approach also results in a redshifted emission with a somewhat lowered photoluminescence quantum yield, but the LEC performance is nevertheless very good. Specifically, an NIR-LEC device comprising a guest-dilute (0.5 molar%) PIDTT-SBS copolymer delivers highly stabile operation at a high radiance of 263 mu W cm(-2) (peak wavelength = 725 nm) and with an external quantum efficiency of 0.214%, which is close to the theoretical limit for this particular emitter and device geometry.

  • 12.
    Tang, Shi
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. LunaLEC AB.
    Murto, Petri
    Wang, Jia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Larsen, Christian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. LunaLEC AB.
    Andersson, Mats R.
    Wang, Ergang
    Edman, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. LunaLEC AB.
    On the Design of Host-Guest Light-Emitting Electrochemical Cells: Should the Guest be Physically Blended or Chemically Incorporated into the Host for Efficient Emission?2019Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 7, nr 18, artikel-id 1900451Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It has recently been demonstrated that light‐emitting electrochemical cells (LECs) can be designed to deliver strong emission with high efficiency when the charge transport is effectuated by a majority host and the emission is executed by a minority guest. A relevant question is then: should the guest be physically blended with or chemically incorporated into the host? A systematic study is presented that establishes that for near‐infrared‐(NIR‐) emitting LECs based on poly(indacenodithieno[3,2‐b]thiophene) (PIDTT) as the host and 4,7‐bis(4,4‐bis(2‐ethylhexyl)‐4H‐silolo[3,2‐b:4,5‐b′]dithiophen‐2‐yl)benzo[c][1,2,5]‐thiadiazole (SBS) as the guest the chemical‐incorporation approach is preferable. The host‐to‐guest energy transfer in LEC devices is highly efficient at a low guest concentration of 0.5%, whereas guest aggregation and ion redistribution during device operation severly inhibits this transfer in the physical‐blend devices. The chemical‐incorporation approach also results in a redshifted emission with a somewhat lowered photoluminescence quantum yield, but the LEC performance is nevertheless very good. Specifically, an NIR‐LEC device comprising a guest‐dilute (0.5 molar%) PIDTT‐SBS copolymer delivers highly stabile operation at a high radiance of 263 µW cm−2 (peak wavelength = 725 nm) and with an external quantum efficiency of 0.214%, which is close to the theoretical limit for this particular emitter and device geometry.

  • 13.
    Vasileva, Elena
    et al.
    Department of Applied Physics, KTH, Stockholm, Sweden.
    Chen, Hui
    Wallenberg Wood Science Center, Department of Fiber and Polymer Technology, KTH, Stockholm, Sweden.
    Li, Yuanyuan
    Wallenberg Wood Science Center, Department of Fiber and Polymer Technology, KTH, Stockholm, Sweden.
    Sychugov, Ilya
    Department of Applied Physics, KTH, Stockholm, Sweden.
    Yan, Max
    Department of Applied Physics, KTH, Stockholm, Sweden.
    Berglund, Lars
    Wallenberg Wood Science Center, Department of Fiber and Polymer Technology, KTH, Stockholm, Sweden.
    Popov, Sergei
    Department of Applied Physics, KTH, Stockholm, Sweden.
    Light scattering by structurally anisotropic media: a benchmark with transparent wood2018Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 6, nr 23, artikel-id 1800999Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transparent wood (TW) is a biocomposite material with hierarchical structure, which exhibits high optical transmittance and anisotropic light scattering. Here, the relation between anisotropic scattering and the internal structure of transparent wood is experimentally studied and the dependence of scattering anisotropy on material thickness, which characterizes the fraction of ballistic photons in the propagating light, is shown. The limitations of the conventional haze, as it is implemented to isotropic materials, are discussed, and a modified characteristic parameter of light scattering—the degree of anisotropic scattering is defined. This parameter together with the transport mean free path value is more practical and convenient for characterization of the material scattering properties. It is believed that the generic routine described in this paper can be applied for scattering characterization and comparison of other TW materials of either different thickness, optical quality or based on various wood species.

  • 14. Xiong, Wenjing
    et al.
    Tang, Shi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Murto, Petri
    Zhu, Weiguo
    Edman, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Wang, Ergang
    Combining Benzotriazole and Benzodithiophene Host Units in Host-Guest Polymers for Efficient and Stable Near-Infrared Emission from Light-Emitting Electrochemical Cells2019Ingår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 7, nr 15, artikel-id 1900280Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A set of host-guest copolymers with alternating benzodithiophene and benzotriazole (BTz) derivatives as host units and 4,7-bis(5-bromothiophen-2-yl)-benzo[c][1,2,5]thiadiazole as the minority guest are synthesized, characterized, and evaluated for applications. A light-emitting electrochemical cell (LEC) comprising such a host-guest copolymer delivers fast-response near-infrared (NIR) emission peaked at 723 nm with a high radiance of 169 mu W cm(-2) at a low drive voltage of 3.6 V. The NIR-LEC also features good stability, as the peak NIR output only drops by 8% after 350 h of continuous operation. It is, however, found that the LEC performance is highly sensitive to the detailed chemical structure of the host backbone, and that the addition of electron-donating thiophene bridging units onto the BTz unit is highly positive while the inclusion of fluorine atoms results in a drastically lowered performance, presumably because of the emergence of hydrogen bonding within the active material.

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