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The comparison of performance of positive electrodes of lithium-sulfur batteries made using the binders based on fluoroplastic (PVDF Solef 5310 and Kynar) and polyethylene oxide (PEO) was carried out. The electrodes made using PVDF Kynar or limited amounts of PEO were shown to have certain advantages. It was also found that electrodes with PEO had an increased specific capacity during the initial period of cycling, whereas electrodes with Kynar were characterized by the minimum capacity fading during cycling.

Polymer electrolyte based on Nafion-117 membranes in the Li+ form with intercalated 1,3-dioxolane-dimethoxyethane solvent mixtures (DOL-DME) has been obtained. The obtained electrolyte Nafion-Li+-DOL-DME has been characterized by DSC analysis, IR- and impedance spectroscopy. The solvent uptake of membrane in the DOL-DME mixture amounts to 1.9. Nafion-Li+-DOL-DME is characterized by an ionic conductivity ~10−7 S cm−1 at room temperature. The comparative study of the electrochemical properties of Li–S batteries with liquid electrolyte (1M Li(CF3SO2)2N in DOL-DME) with polypropylene film (PP) or Nafion-Li+-DOL-DME and S/C composites with mesoporous carbon as cathode materials has shown that the use of membrane can improve cyclability of the cell. The first-cycle discharge capacities of S/C electrodes in the Li–S battery cells with PP and Nafion-Li+-DOL-DME were 730 and 450 mAh g−1, respectively (0.1 mV s−1). However, the discharge capacity of S/C in the cell with PP reduced significantly after 10 cycles. The Li–S battery with the use of membrane exhibits significantly enhanced cyclability. The discharge capacity of S/C in the cell with Nafion-Li+-DOL-DME amounts to 365 mAh g−1 after 10 cycles and to up to 290 mAh g−1 after 40 cycles. [ABSTRACT FROM AUTHOR]

We measured the picoseconds (ps) transient photomodulation (PM) dynamics of photoexcitations in blends of regio-regular poly(3-hexyl-thiophene) [RR-P3HT] (donors-D) and indene-C60 bisadduct (fullerene derivative) [ICBA] (acceptor-A) that phase-separate into D- and A-nano-domains, in a broad spectral range from 0.25 to 2.5 eV; in comparison with steady state PM spectra. We correlate our measurements with organic photovoltaic solar cell performance made from the same D and A materials. In D-A blends of RR-P3HT/ICBA with (1.2:1) weight ratio having solar cell power conversion efficiency of ∼5.1%, we found that although the intrachain excitons in the polymer nano-domains decay within ∼10 ps, no charge polarons are generated on their expense up to ∼1 ns. Instead, there is a built-up of charge-transfer (CT) excitons at the D-A domain interfaces that occurs with the same kinetics as the exciton decay. The CT excitons dissociate into separate polarons in the D- and A-nano-domains at a much later time (>1 ns). This 'two-step' charge photogeneration process is typical in organic bulk heterojunction cells. Our results emphasize the important role of the CT state in generating free charge polarons in organic solar cells. [ABSTRACT FROM AUTHOR]

Tailoring of electromagnetic spontaneous emission predicted by E. M. Purcell more than 50 years ago has undoubtedly proven to be one of the most important effects in the rich areas of quantum optics and nanophotonics. Although during the past decades the research in this field has been focused on electric dipole emission, the recent progress in nanofabrication and study of magnetic quantum emitters, such as rare-earth ions, has stimulated the investigation of the magnetic side of spontaneous emission. Here, we review the state-of-the-art advances in the field of spontaneous emission enhancement of magnetic dipole quantum emitters with the use of various nanophotonics systems. We provide the general theory describing the Purcell effect of magnetic emitters, overview realizations of specific nanophotonics structures allowing for the enhanced magnetic dipole spontaneous emission, and give an outlook on the challenges in this field, which remain open to future research. [ABSTRACT FROM AUTHOR]

[Display omitted] In this work, a new cathode material for lithium–sulfur (Li–S) batteries was developed. Microporous carbon (with predominant pore size £ 1.2 nm) served as both a matrix for sulfur retention and conductive additive. Microporous carbon was shown to be capable of adsorbing lithium polysulfides thereby suppressing their migration toward lithium anode. The discharge capacity of the S/C composite at the 1st and 20th cycles in Li–S battery operation was 513 and 421 mAh g–1 at a scan rate of 0.1 mV s–1. [ABSTRACT FROM AUTHOR]

Engineering of intensity and direction of radiation from a single quantum emitter by means of structuring of their environment at the nanoscale is at the cornerstone of modern nanophotonics. Systems exhibiting spin-orbit coupling of light are of particular interest in this context. In this letter, we have demonstrated that the asymmetrical excitation of a high-index subwavelength (λ/3-λ/2) dielectric nanoparticle by a point dipole source located in a notch at its surface results in formation of a chiral near field, which is similar to that of a circularly polarized dipole or quadrupole. Using numerical simulations, we have shown that this effect is the result of a higher multipole (quadrupole and octupole) modes excitation within the nanoparticle. We have applied this effect for unidirectional excitation of dielectric waveguide and surface plasmon-polariton modes. We have achieved the value of front-to-back ratio up to 5.5 for dielectric waveguide and to 7.5 for the plasmonic one. Our results are important for the integrated nanophotonics and quantum information processing systems. [ABSTRACT FROM AUTHOR]

We employed a cross correlation method to study current noise in phosphorescent organic light-emitting diodes. The noise spectra revealed two frequency-dependent components. The first component displays \({1/f}^{1.3}\) dependence and correlates with the light emission of the devices. The second component is dominant in low-bias regime and varies as \({1/f}^{2.8}\) . It is attributed to inhomogeneities of the barrier height at metal/organic interface. The extended bandwidth of the method allowed us to resolve frequency-independent term in the noise power, which was dominated by the shot noise. At bias voltages from 2.4 to 2.5 V, the Fano factor characterizing shot noise is close to one, confirming that the electron transport in this regime is limited by the carrier injection across metal/organic interface. At higher biases, in the regime where the transport is bulk-limited, the Fano factors drops to 0.5. Possible physical reasons for such behavior are discussed. [ABSTRACT FROM PUBLISHER]

Latest developments in solution processed hole injection layer (HIL) technology that has enabled near-ohmic injection into OLED stacks will be presented. Some of the advantages inherent to solution processing will be demonstrated including the planarization of low cost engineered OLED substrates. [ABSTRACT FROM AUTHOR]

We used a variety of steady state and transient optical techniques for studying the primary and steady state photoexcitations in pristine films of poly(3-hexylthiophene) [P3HT] with different molecular weight used for organic photovoltaic solar cells. The employed techniques include picosecond transient and steady state photoluminescence and photomodulation spectroscopies, laser action, and doping induced absorption. We show that solar cell device qualities based on donor-acceptor blends of the P3HT polymers with substituted fullerene molecules crucially depend on the polymer properties, which can be readily discerned by the steady state photomodulation technique. This technique can, therefore, be applied to specific polymer donors for estimating their solar cell device properties prior to actually fabricating an optimal device. [ABSTRACT FROM AUTHOR]

In this paper, a technique based on the auto correlation Junction is proposed to estimate the Doppler spread in Rayleigh fading channels for mobile OFDM systems. It is simply implemented with the cyclic structure of OFDM symbols, and any other additive data and pilots need not to be inserted into the common OFDM symbols. This algorithm can be applied directly to the OFDM system with transmit diversity (TD) and to MIMO OFDM systems. Computer simulation results are included to support our developments in the terms of mean estimation value and mean square error. [ABSTRACT FROM AUTHOR]

We present recent developments of our core technologies targeted towards solution based OLED device manufacturing including non-aqueous (NQ) hole injection layer and solution processed hole transport layer. We demonstrate low voltage, and long lifetime devices with non-aqueous hole injection layer. Also, comparable performance with our intractable solution processed HTL versus NPB vapor HTL has been demonstrated in vapor WOLED devices in combination with our NQ hole injection layer technology. [ABSTRACT FROM AUTHOR]

We have fabricated efficient organic light emitting diodes using strong, transparent carbon nanotube (CNT) sheets as the hole-injecting anode. These devices show a brightness of 4500 cd/m2 and current efficiency near 2.5 cd/A, which is close to the efficiency we achieve with a similar device, which uses indium tin oxide (ITO) as the anode. We demonstrate that proper planarization of the electrode using the water-soluble polymer poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) is necessary for achieving high efficiency and can be accomplished by spin casting multiple layers. We believe that increased conductivity of the sheets could lead to CNT-based devices with efficiencies exceeding those on ITO. [ABSTRACT FROM AUTHOR]

The article is devoted to the consideration of the essential problems of accounting institution formation under the sustainable development of the country and the region. The research is based on the key research the field of the intuition economics and considers the trends of institutional changes including incremental, evolutionary and revolutionary. Approaches to the analysis of institutions are presented as well. The first approach states that economic efficiency is guaranteed by newly emerging institutions. The second approach involves certain internal and external incentives for changing institutions. Whereas the third approach insists on considering institutional changes to be the relation of individual economic entities to institutional innovations in terms of the net benefit from their implementation. The conclusion draws the leading role of the state in the process of the emergence and further development of newly created institutions focusing on the fact that not every change leads to greater efficiency. Thus it is crucial to consider the previous background of institutions development at implementing changes in accounting and control.

Extraction of electromagnetic energy by an antenna from impinging external radiation is at the basis of wireless communications and wireless power transfer (WPT). The maximum of transferred energy is ensured when the antenna is conjugately matched, i.e., when it is resonant and it has an equal coupling with free space and its load. This condition, however, can be easily affected by changes in the environment, preventing optimal operation of a WPT system. Here, we introduce the concept of coherently enhanced WPT that allows us to bypass this difficulty and achieve dynamic control of power transfer. The approach relies on coherent excitation of the waveguide connected to the antenna load with a backward propagating signal of specific amplitude and phase. This signal creates a suitable interference pattern at the load resulting in a modification of the local wave impedance, which in turn enables conjugate matching and a largely increased amount of extracted energy. We develop a simple theoretical model describing this concept, demonstrate it with full-wave numerical simulations for the canonical example of a dipole antenna, and verify experimentally in both near-field and far-field regimes. [ABSTRACT FROM AUTHOR]

We measured the picoseconds (ps) transient dynamics of photoexcitations in blends of poly(3-hexyl-thiophene) (P3HT; donors-D) and fullerene [6,6]-phenyl-C61-butyric acid methyl ester (PCBM; acceptor-A), using the transient pump/probe photomodulation technique in an unprecedented broad spectral range from 0.25 to 2.5 eV, and compared the results with organic solar cell performance based on the same blends. In D-A blends with maximum domain separation such as regio-regular P3HT/PCBM with (1.2:1) weight ratio having solar cell power conversion efficiency of ∼4%, we found that, although the photogenerated intrachain excitons in the polymer nano-domains decay within ∼10 ps, no charge polarons are generated on their expense up to ∼2 ns. Instead, there is a buildup of charge transfer (CT) excitons at the D-A interfaces having the same kinetics as the exciton decay, which dissociate into separate polarons in the D and A domains at a much later time (≫1 ns). This two-step charge photogeneration process may be typical in organic bulk heterojunction cells. Although the CT excitons are photogenerated on the exciton expense much faster in D-A blends having smaller domain size such as in regio-random P3HT/PCBM, their dissociation is less efficient because of larger binding energy. This explains the poor solar cell power conversion efficiency (<0.1%) based on this blend. Our results support the two-step charge photogeneration mechanism in polymer/fullerene blends and emphasize the important role of the CT binding energy in generating free charge polarons in organic solar cells. [ABSTRACT FROM AUTHOR]

Coupling of electric and magnetic responses of a scatterer, known as bianisotropy, enables rich physics and unique optical phenomena, including asymmetric absorption or reflection, one-way transparency, and photonic topological phases. Here we demonstrate yet another feature stemming from bianisotropic response, namely, polarization-dependent scattering of light by bianisotropic dielectric meta-atom with broken mirror symmetry, which yields a photonic analogue of spin Hall effect. Based on a simple dipole model, we explain the origin of the effect confirming our conclusions by experimental observation of photonic spin Hall effect both for a single meta-atom and for an array of them.