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Science and Technology of Advanced Materials

Ayumi Ishii, Yuya Adachi, Ayaka Hasegawa, Miyu Komaba, Shuhei Ogata, Miki Hasegawa
Multicolor upconversion luminescence of Er3+ was successfully enhanced by optimizing the interface in dye-coordinated nanoparticles with a core/shell structure. Red and green upconversion emissions of Er3+ were obtained at the interface of oxide nanoparticles via the intramolecular energy transfer from the coordinating squaraine dye with high light-absorption ability, which was more efficient than emissions through the energy transfer from metal ions such as Yb3+ . Additionally, CaF2 nanoparticles as a core material minimized the energy loss with nonradiative downward relaxations in Er3+ , resulting in the observation of unusual blue upconversion emissions from the upper energy level of Er3+ by nonlaser excitation using a continuous-wave (CW) Xe lamp at an excitation power of 1...
2019: Science and Technology of Advanced Materials
Roland Hany, Hong Lin, Fernando A Castro
No abstract text is available yet for this article.
2019: Science and Technology of Advanced Materials
Joo Won Han, Chul Woong Joo, Jonghee Lee, Dong Jin Lee, Jisoo Kang, Seunggun Yu, Woo Jin Sung, Nam Sung Cho, Yong Hyun Kim
We demonstrate high-performance down-conversion microlens array (DC-MLA) films for white organic light-emitting diodes (OLEDs). The DC-MLA films are readily fabricated by an imprinting method based on breath figure patterns, which are directly formed on the polymer substrate with a novel concept. The DC-MLA films result in high-quality white light as well as enhanced light outcoupling efficiency for white OLEDs. The external quantum efficiency and power efficiency of OLEDs with DC-MLA films are increased by a factor of 1...
2019: Science and Technology of Advanced Materials
Yujing Liu, Simon Zeder, Sen Lin, Romain Carron, Günter Grossmann, Sami Bolat, Shiro Nishiwaki, Frank Clemens, Thomas Graule, Ayodhya N Tiwari, Hui Wu, Yaroslav E Romanyuk
We explore the feasibility of Ag fiber meshes as electron transport layer for high-efficiency flexible Cu(In,Ga)Se2 (CIGS) solar cells. Woven meshes of Ag fibers after UV illumination and millisecond flash-lamp treatment results in a sheet resistance of 17 Ω/sq and a visible transmittance above 85%. Conductive Ag meshes are integrated into flexible CIGS cells as transparent conductive electrode (TCE) alone or together with layers of Al-doped ZnO (AZO) with various thickness of 0…900 nm. The Ag mesh alone is not able to function as a current collector...
2019: Science and Technology of Advanced Materials
Ryo Matsumoto, Zhufeng Hou, Masanori Nagao, Shintaro Adachi, Hiroshi Hara, Hiromi Tanaka, Kazuki Nakamura, Ryo Murakami, Sayaka Yamamoto, Hiroyuki Takeya, Tetsuo Irifune, Kiyoyuki Terakura, Yoshihiko Takano
Candidate compounds for new thermoelectric and superconducting materials, which have narrow band gap and flat bands near band edges, were exhaustively searched by the high-throughput first-principles calculation from an inorganic materials database named AtomWork. We focused on PbBi2 Te4 which has the similar electronic band structure and the same crystal structure with those of a pressure-induced superconductor SnBi2 Se4 explored by the same data-driven approach. The PbBi2 Te4 was successfully synthesized as single crystals using a melt and slow cooling method...
2018: Science and Technology of Advanced Materials
Enrico Avancini, Debora Keller, Romain Carron, Yadira Arroyo-Rojas Dasilva, Rolf Erni, Agnieszka Priebe, Simone Di Napoli, Martina Carrisi, Giovanna Sozzi, Roberto Menozzi, Fan Fu, Stephan Buecheler, Ayodhya N Tiwari
Structural defects such as voids and compositional inhomogeneities may affect the performance of Cu(In,Ga)Se2 (CIGS) solar cells. We analyzed the morphology and elemental distributions in co-evaporated CIGS thin films at the different stages of the CIGS growth by energy-dispersive x-ray spectroscopy in a transmission electron microscope. Accumulation of Cu-Se phases was found at crevices and at grain boundaries after the Cu-rich intermediate stage of the CIGS deposition sequence. It was found, that voids are caused by Cu out-diffusion from crevices and GBs during the final deposition stage...
2018: Science and Technology of Advanced Materials
Roman Anufriev, Masahiro Nomura
Phononic crystals have been studied for the past decades as a tool to control the propagation of acoustic and mechanical waves. Recently, researchers proposed that nanosized phononic crystals can also control heat conduction and improve the thermoelectric efficiency of silicon by phonon dispersion engineering. In this review, we focus on recent theoretical and experimental advances in phonon and thermal transport engineering using pillar-based phononic crystals. First, we explain the principles of the phonon dispersion engineering and summarize early proof-of-concept experiments...
2018: Science and Technology of Advanced Materials
Lei Wang, Jing Wen, Cihui Yang, Bangshu Xiong
Electrical probe memory has received considerable attention during the last decade due to its prospective potential for the future mass storage device. However, the electrical probe device with conventional diamond-like carbon capping and bottom layers encounters with large interfacial contact resistance and difficulty to match the experimentally measured properties, while its analog with titanium nitride capping and bottom layers also faces serious heat dissipation through either probe and silicon substrate...
2018: Science and Technology of Advanced Materials
Ciarán Manus Maguire, Matthias Rösslein, Peter Wick, Adriele Prina-Mello
We present here a perspective detailing the current state-of-the-art technologies for the characterisation of nanoparticles (NPs) in liquid suspension. We detail the technologies involved and assess their applications in the determination of NP size and concentration. We also investigate the parameters that can influence the results and put forward a cause and effect analysis of the principle factors influencing the measurement of NP size and concentration by NP tracking analysis and dynamic light scattering, to identify areas where uncertainties in the measurement can arise...
2018: Science and Technology of Advanced Materials
Martina Lingg, Annina Spescha, Stefan G Haass, Romain Carron, Stephan Buecheler, Ayodhya N Tiwari
The performance improvement of conventional CdTe solar cells is mainly limited by doping concentration and minority carrier life time. Alloying CdTe with an isovalent element changes its properties, for example its band gap and behaviour of dopants, which has a significant impact on its performance as a solar cell absorber. In this work, the structural, optical, and electronic properties of CdTe1-x Sex films are examined for different Se concentrations. The band gap of this compound changes with composition with a minimum of 1...
2018: Science and Technology of Advanced Materials
Mohammed Makha, Philippe Schwaller, Karen Strassel, Surendra B Anantharaman, Frank Nüesch, Roland Hany, Jakob Heier
The efficiency of ternary organic solar cells relies on the spontaneous establishment of a nanostructured network of donor and acceptor phases during film formation. A fundamental understanding of phase composition and arrangement and correlations to photovoltaic device parameters is of utmost relevance for both science and technology. We demonstrate a general approach to understanding solar cell behavior from simple thermodynamic principles. For two ternary blend systems we construct and model phase diagrams...
2018: Science and Technology of Advanced Materials
Takuya Tsukamoto, Yohei Umino, Sachie Shiomi, Kou Yamada, Takaaki Suzuki
This paper proposes a bimorph piezoelectric vibration energy harvester (PVEH) with a flexible 3D meshed-core elastic layer for improving the output power while lowering the resonance frequency. Owing to the high void ratio of the 3D meshed-core structure, the bending stiffness of the cantilever can be lowered. Thus, the deflection of the harvester and the strain in the piezoelectric layer increase. According to vibration tests, the resonance frequency is 15.8% lower and the output power is 68% higher than in the conventional solid-core PVEH...
2018: Science and Technology of Advanced Materials
Takeshi Onishi, Takuya Kadohira, Ikumu Watanabe
In this study, we develop a computer-aided material design system to represent and extract knowledge related to material design from natural language texts. A machine learning model is trained on a text corpus weakly labeled by minimal annotated relationship data (~100 labeled relationships) to extract knowledge from scientific articles. The knowledge is represented by relationships between scientific concepts, such as { annealing, grain size, strength }. The extracted relationships are represented as a knowledge graph formatted according to design charts, inspired by the process-structure-property-performance (PSPP) reciprocity...
2018: Science and Technology of Advanced Materials
Gao Yang, Lihua Li, Wing Bun Lee, Man Cheung Ng
Monolayer graphene exhibits extraordinary properties owing to the unique, regular arrangement of atoms in it. However, graphene is usually modified for specific applications, which introduces disorder. This article presents details of graphene structure, including sp2 hybridization, critical parameters of the unit cell, formation of σ and π bonds, electronic band structure, edge orientations, and the number and stacking order of graphene layers. We also discuss topics related to the creation and configuration of disorders in graphene, such as corrugations, topological defects, vacancies, adatoms and sp3 -defects...
2018: Science and Technology of Advanced Materials
Peter J Holliman, Christopher Kershaw, Arthur Connell, Eurig W Jones, Robert Hobbs, Rosie Anthony, Leo Furnell, James McGettrick, Dawn Geatches, Sebastian Metz
Dye-sensitized solar cells (DSCs) have been the subject of wide-ranging studies for many years because of their potential for large-scale manufacturing using roll-to-roll processing allied to their use of earth abundant raw materials. Two main challenges exist for DSC devices to achieve this goal; uplifting device efficiency from the 12 to 14% currently achieved for laboratory-scale 'hero' cells and replacement of the widely-used liquid electrolytes which can limit device lifetimes. To increase device efficiency requires optimized dye injection and regeneration, most likely from multiple dyes while replacement of liquid electrolytes requires solid charge transporters (most likely hole transport materials - HTMs)...
2018: Science and Technology of Advanced Materials
Ido Gardi, Yael G Mishael
A novel, stimuli-responsive composite, based on poly(4-vinylpyridine) (PVP) brushes, end-grafted to montmorillonite clay (GPC), was designed as a regenerable sorbent for efficient removal of pollutants from water. We characterized the novel composite sorbent and its response to pH, employing Fourier transform infrared, X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetry analysis and zeta potential measurements. In comparison with conventional, electrostatically adsorbed PVP composites (APC), the GPC presented superior characteristics: higher polymer loading without polymer release, higher zeta potential and lower pH/charge dependency...
2018: Science and Technology of Advanced Materials
Yoshiyuki Nonoguchi, Ami Takata, Chigusa Goto, Takuya Kitano, Tsuyoshi Kawai
The effects of polymer structures on the thermoelectric properties of polymer-wrapped semiconducting carbon nanotubes have yet to be clarified for elucidating intrinsic transport properties. We systematically investigate thickness dependence of thermoelectric transport in thin films containing networks of conjugated polymer-wrapped semiconducting carbon nanotubes. Well-controlled doping experiments suggest that the doping homogeneity and then in-plane electrical conductivity significantly depend on film thickness and polymer species...
2018: Science and Technology of Advanced Materials
Meng Jin, Rao Fu, Changmei Sun, Rongjun Qu, Chunnuan Ji, Ying Zhang, Ying Wang
A series of bridged polysilsesquioxane (BPS) materials was synthesized by the sol-gel method from 3-chloropropyl trimethoxysilane, diethylenetriamine (DETA) or ethylenediamine. Tetraethyl orthosilicate (TEOS) and/or one of the two templates, hexadecyl trimethyl ammonium bromide (CTAB) or P123, were used in the co-condensation process to construct some of the porous adsorbents. The adsorption of Au(III) was the highest for samples without TEOS, especially for the DETA series with CTAB template. This study elucidates the synthesis and applications of BPS materials...
2018: Science and Technology of Advanced Materials
Andrei Ionut Mardare, Cezarina Cela Mardare, Jan Philipp Kollender, Silvia Huber, Achim Walter Hassel
A thin film combinatorial library deposited by co-sputtering of Hf, Nb and Ta was employed to characterise fundamental properties of the Hf-Nb-Ta system. Compositional mappings of microstructure and crystallography revealed similarities in alloy evolution. Distinct lattice distortion was observed upon addition of hexagonal Hf, leading to amorphisation of alloys containing more than 32 at.% Hf and less than 27 and 41 at.% Nb and Ta, respectively. Volta potential and open circuit potential mappings indicated minimal values for the highest Hf concentration...
2018: Science and Technology of Advanced Materials
Kiyoshi Kanie, Moe Sakaguchi, Fumiya Muto, Mami Horie, Masafumi Nakaya, Toshiyuki Yokoi, Atsushi Muramatsu
Substitution of Al atoms in a zeolite framework by catalytic metal atoms has attracted considerable attention because the catalytic behavior can be tuned by the substituted atoms. In the present study, Sn-substituted MFI-type silicates were synthesized using a hydrothermal reaction of an amorphous Si-O-Sn precursor prepared by mechanochemical grinding of SiO2 and Sn(OH)4 . The mechanochemical treatment was found to be a key technique for obtaining the amorphous Si-O-Sn precursor, where tetrahedral Sn4+ species were incorporated into the amorphous matrix...
2018: Science and Technology of Advanced Materials
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