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As an accurate 2D/3D fabrication tool, inkjet printing technology has great potential in preparation of micro electronic devices. The morphology of droplets produced by the inkjet printer has a great impact on the accuracy of deposition. In this study, the drop-on-demand (DoD) inkjet simulation model was established, and the accuracy of the simulation model was verified by corresponding experiments. The simulation result shows that the velocity of the droplet front and tail, as well as the time to disconnect from the nozzle is mainly affected by density (1), viscosity (µ) and surface tension (s) of droplets. When the liquid filament is about to disconnect from the nozzle, the filament length and filament front velocity are found to have a linear correlation with s/µ and ln(/(µs 2 1)). [ABSTRACT FROM AUTHOR]

Abstract: High oxygen radical stability of electrolyte solvent is a key parameter necessary to overcome a large voltage gap in discharge–charge profiles of the non-aqueous Li–air battery. We have proposed N-methyl-N-propylpiperidinium bis(trifluoromethansulfonyl)amide (PP13TFSA) as an appropriate candidate of the electrolyte solvent. PP13TFSA based Li–O2 cells enabled us to draw low charging voltage of around 3.3 V, lowering the voltage gap by nearly half in comparison with those of conventional carbonate-based cells (c.a. 1.4 V). Here, through the detailed analyses of discharge products, we verified the fact that the voltage gap was notably decreased by using the highly radical stable electrolyte solvent. TEM-EELS and FT-IR analyses indicated that Li2O2 was deposited as a discharge product. 13C NMR spectroscopy suggested that no decomposed species derived from electrolyte decomposition was observed from a discharged cathode. GC–MS analyses also revealed that CO and CO2 gases as indices of the decomposed species were not monitored at all. Above-described data substantiated a desirable discharge reaction, resulting in low charging voltage as well as small voltage gap. Design of electrolyte solvents based on their oxygen radical stability and full understanding of the cathode reaction mechanism contributed greatly to a dramatic improvement of the Li–air battery performances. [Copyright &y& Elsevier]

We have fabricated and compared photocurrent generation properties of electropolymerized films consisting of 2,2'-bithiophene and a porphyrin derivative, 5,10,15,20-tetra(3-thienyl)-21H,23H-porphyrin or 5,10,15,20-tetra(2-thienyl)-21H,23H-porphyrin. It was found that the location and the concentration of porphyrin moieties in the films were different between the two porphyrin monomers, and the polymer film with the former porphyrin gave larger photocurrent than the latter. The result indicates that the molecular design of the polymer electrode is very important for effective photocurrent generation. [ABSTRACT FROM AUTHOR]

Abstract: The influence of C60 as a buffer layer on photovoltaic performance and stability of bulk hetero-junction solar cells using a photoactive layer of CdTe nanocrystals and poly(p-phenylenevinylene) derivative has been investigated. The incident photon-to-current conversion efficiency of the sealed-cells with a C60 buffer layer was about 70% of that of solar cells using a buffer layer of LiF. The introduction of C60 buffer layer gave an improvement in the stability for a light-harvesting test. In a long-term thermal stability test, there was no difference between the solar cells using C60 and LiF. An impedance analysis suggested that the degradation of the performance in the stability tests was associated with a decrease in the conductance of the cells. [Copyright &y& Elsevier]

Abstract: Wet-type organic solar cells containing 5,10,15,20-3-tetrathienylporphyrin (TThP) and polythiophene (PTh) films were fabricated. The TThP/PTh film was prepared on indium-tin-oxide (ITO) glass using an electrochemical polymerization method in an n-Bu4NPF6/CH2Cl2 solution. It was found that a small amount of iodine doping of the film improved the incident photon-to-electron conversion efficiency (IPCE) of a solar cell consisting of a TThP/PTh film and an aqueous electrolyte. A HOMO level measurement suggested that a modified HOMO level of the low iodine-doped TThP/PTh film allowed a fast electron transfer from PTh to a porphyrin moiety. To obtain further improvement, a sandwich-type solar cell using a 5% (w/w) aqueous solution of acetonitrile containing 0.05M iodine and 0.5M lithium iodide as an electrolyte was then fabricated. The solar cell absorbed light in the 300–800nm wavelength range, converting this to a cathodic photocurrent with a maximum IPCE of 32% at 430nm under irradiation of 5.0×1014 photoncm−2 s−1. This value is about 10 times higher than that of the solar cells using an aqueous electrolyte. The total energy conversion efficiency (η) of the solar cell under simulated sunlight reached 0.12% for 2.59mWcm−2 at AM1.5 and 0.05% for 100mWcm−2 at air mass 1.5. [Copyright &y& Elsevier]

A new gas-utilizing battery using mixed gas of O2and CO2was developed and proved its very high discharge capacity. The capacity reached three times as much as that of a non-aqueous Li–air (O2) battery. The unique point of the battery is expected to be the rapid consumption of superoxide anion radical by CO2as well as the slow filling property of the Li2CO3in the cathode. [ABSTRACT FROM AUTHOR]

A Z-scheme type photoelectrochemical cell consisting of an electrochemically polymerized photoactive electrode and a dye-sensitized TiO2electrode is demonstrated. Nearly 1 V of open circuit voltage (VOC) was achieved by the cooperation of a couple of photoactive electrodes toward uphill electron pumping. [ABSTRACT FROM AUTHOR]

Abstract: Li-air battery using ionic liquids, N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis (trifluoromethylsulfonyl) amide (DEME-TFSA) and N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)amide (PP13-TFSA), as the solvents for electrolyte have been studied. A significant improvement of discharge capacity has been observed for DEME-TFSA (4315 mAh g−1-electrode at current density of 0.1 mA cm−2), compared with PP13-TFSA. As a discharged product, aggregates reaching 4 μm diameter in size are formed on the surface of cathode, almost 80% of the products are decomposed after charge. By using Raman spectroscopy, two typical peaks attributed to Li2O2 were detected from the discharged aggregates. From the cross sectional SEM images, vacancy occupation ratios of discharged and charged electrodes are estimated, and they are in good agreement with the theoretical calculations. The discharged products formed inside of the cathode are not decomposed completely by charge. [Copyright &y& Elsevier]

Different-sized CdSe quantum dots have been assembled on TiO2 films composed of particle and nanotube morphologies using a bifunctional linker molecule. Upon band-gap excitation, CdSe quantum dots inject electrons into TiO2 nanoparticles and nanotubes, thus enabling the generation of photocurrent in a photoelectrochemical solar cell. The results presented in this study highlight two major findings: (i) ability to tune the photoelectrochemical response and photoconversion efficiency via size control of CdSe quantum dots and (ii) improvement in the photoconversion efficiency by facilitating the charge transport through TiO2 nanotube architecture. The maximum IPCE (photon-to-charge carrier generation efficiency) obtained with 3 nm diameter CdSe nanoparticles was 35% for particulate TiO2 and 45% for tubular TiO2 morphology. The maximum IPCE observed at the excitonic band increases with decreasing particle size, whereas the shift in the conduction band to more negative potentials increases the driving force and favors fast electron injection. The maximum power-conversion efficiency ≤1% obtained with CdSe-TiO2 nanotube film highlights the usefulness of tubular morphology in facilitating charge transport in nanostructure-based solar cells. Ways to further improve power-conversion efficiency and maximize light-harvesting capability through the construction of a rainbow solar cell are discussed. [ABSTRACT FROM AUTHOR]

The kinetics of the oxygen reduction reaction (ORR) on the practical air cathode in a Lithium-air cell, which is conventionally composed of porous carbon with or without catalysts supported on it, was investigated. The mechanism and kinetics of the oxygen reduction reaction (ORR) was studied on a porous carbon electrode in an oxygen saturated solution of 0.1 M Lithium bis-trifluoromethanesulfonimide (LiTFSI) in Dimethoxyethane (DME) using cyclic voltammetery (CV) and the rotating ring-disk electrode (RRDE) technique. The oxygen reduction and evolution reactions were found to occur at similar potentials to those observed on a smooth, planar glassy carbon (GC) electrode. The effect of porosity and the resultant increase in surface area were readily observed in the increase in the transient time required for the intermediates to reach the ring and the much larger disk currents (compared to smooth, planar GC) recorded respectively. The RRDE data was analyzed using a kinetic model previously developed by us and the rate constants for the elementary reactions were calculated. The rates constant for the electrochemical reactions were found to be similar in magnitude to the rate constants calculated for smooth GC disks. The porosity of the electrode was found to decrease the rate of desorption of the intermediate and the product and delay their diffusion by shifting it from a Fickian regime in the electrolyte bulk to the Knudsen regime in the film pores. Thus, it is shown that the effect of the electrode porosity on the kinetics of the ORR is physical rather than electrochemical. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction in an ionic liquid (IL) consisting of N , N -diethyl- N -methyl- N -(2-methoxyethyl)ammonium (DEME) cation and the bis(trifluoromethanesulfonyl)imide (TFSI) anion was investigated in the anhydrous and water saturated conditions respectively. The IL was demonstrated to be stable in the operating range of a lithium air cell in both the anhydrous and water saturated conditions. The addition of water was found to lower the overpotential for the oxygen reduction reaction by 40 mV. Finally, the reaction rate constant was found to increase by an order of magnitude with the addition of water hence demonstrating the tendency of water to promote/catalyze the oxygen electrochemistry in non-aqueous systems. [ABSTRACT FROM AUTHOR]

A novel indirect charging system that uses a redox mediator was demonstrated for Li–O2 batteries. 4-Methoxy-2,2,6,6-tetramethylpiperidinyl-1-oxyl (MeO-TEMPO) was applied as a mediator to enable the oxidation of Li2O2, even though Li2O2 is electrochemically isolated. This system promotes the oxidation of Li2O2 without parasitic reactions attributed to electrochemical charging and reduces the charging time. [ABSTRACT FROM AUTHOR]

For an autonomous search for electrolyte solutions in electrochemistry, we performed a search task using a parallel Bayesian optimization method with the best composition with maximum lithium (Li) ion conductivity in a mixture of four lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solutions: propylene carbonate (PC), γ-butyrolactone (GBL), tetraethylene glycol diethyl ether (TGDE), and trimethyl phosphate (TMP). The maximum ionic conductivity was achieved using a mixed solution of 98 vol% GBL and 2 vol% TGDE and showed a high Li ionic conductivity in manual measurements. Furthermore, molecular dynamics simulations of a similar electrolyte implied that the small solvation shell of Li-TGDE caused an increase in the ionic conductivity. The reason for this increase is that the dilute TGDE molecules in the GBL solution can be associated with dilute Li ions. [Display omitted] • An original electrolyte optimizer for electrolyte improved throughput by a factor of 10. • Parallel use of different Bayesian algorithm improved optimization stability. • The best composition among PC-GBPL-TMP-TGDE for LiTFSI solution was autonomously determined. • The results of autonomous testing system was validated by manual experiments. • MD simulations illustrated the small Li-ion solvation structure of Li-TGDE-GBL. [ABSTRACT FROM AUTHOR]

Abstract: Ionic liquids composed of N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium (DEME), N-methyl-N-methoxyethylpiperidinium (PP1.1o2) cations functionalized with ethers, N-methyl-N-propylpiperidinium (PP13), and N-butyl-N-methylpyrrolidinium (P14) cations and the bis(trifluoromethanesulfonyl)amide (TFSA) anion are investigated for application as electrolytes in non-aqueous lithium–oxygen (Li–O2) batteries. The PP13–TFSA, P14–TFSA and DEME–TFSA ionic liquids have high oxygen radical stability. A comparison of the lithium supply capacity measured using pulse-gradient spin-echo NMR for 7Li nuclei and the oxygen supply capacity measured using electrochemical methods indicates that the oxygen supply is the rate-limiting step for the generation of lithium–oxygen compounds (LiO x ) in these ionic liquids with supporting electrolytes. The DEME–TFSA system has the highest LiO x generation activity among the ionic liquid systems examined. We demonstrate the improved performance (output power, discharge–charge capacity and coulombic efficiency) of a Li–O2 battery using the DEME–TFSA system compared with that using the PP13–TFSA system. The improvements observed for the DEME–TFSA system are attributed to the high LiO x generation properties and lithium ion supply. [Copyright &y& Elsevier]

Abstract: It is accepted that the reduction of iodine species in non-aqueous solvents occurs through one-electron or two-electron processes below roughly 3.5 V vs. Li/Li+. In some iodine solutions, the molecular complexation of iodine with the organic solvent proceeded via a charge–transfer interaction. Reduction of iodine in non-aqueous solvents having S:glyph name="dbnd" />O groups, as well as interactions of iodine molecules with these solvents, were studied. Iodine molecules associated with dimethyl sulfoxide (DMSO), tetramethylene sulfoxide (TMSO), and trimethyl phosphate (TMP) showed anomalous reduction above+1.0 V vs. NHE. We demonstrated the operation of lithium–iodine batteries using DMSO, TMSO and TMP near 4.0 V vs. Li/Li+. [Copyright &y& Elsevier]

Abstract: An electron donor–acceptor dyad (quaterthiophene–anthraquinone) mediates ultrafast intramolecular photoinduced charge separation and consequent charge recombination when in polar or moderately polar solvents. Alternatively, non-polar media completely impedes the initial photoinduced electron transfer by causing enough destabilization of the charge-transfer state and shifting its energy above the energy of the lowest locally excited singlet state. Furthermore, femtosecond transient-absorption spectroscopy reveals that for the solvents mediating the initial photoinduced electron-transfer process, the charge recombination rates were slower than the rates of charge separation. This behavior of donor–acceptor systems is essential for solar-energy-conversion applications. For the donor–acceptor dyad described in this study, the electron-transfer driving force and reorganization energy place the charge-recombination processes in the Marcus inverted region. [Copyright &y& Elsevier]

To elucidate possible challenges for outdoor practical use of dye-sensitized solar cells, outdoor performance of large scale DSC modules made of series-connected 64 DSC cells have been examined for a half year. This is almost the first long term outdoor test of full-fledged DSC modules. Although DSC modules still need the larger area than conventional Si solar cell modules to attain the same rated output because of lower rated energy conversion efficiency, the measured data teach that DSC modules yearly generated 10–20% more electricity than conventional crystalline-Si modules of the same rated output power. This result also teaches that the energy conversion efficiency obtained by the certified measurement under 1 Sun condition does not always coincide with the electricity generated outdoors yearly, and is not a crucial measure to evaluate the performance of solar cells. The outputs of four modules showed similar monotonous slow and steady decreases, showing potential outdoor use of DSC. Simultaneously, it indicates that there are still remaining challenges to overcome one by one in attaining higher performance keeping long term stability. [Copyright &y& Elsevier]

The conduction of the bivalent magnesium cation, Mg2+, in an inorganic solid state material, Mg(BH4)(NH2), has been demonstrated. This material exhibited a high ionic conductivity of 10−6 S cm−1 at 150 °C, and its electrochemical window was estimated to be approximately 3 V using cyclic voltammetry. [ABSTRACT FROM AUTHOR]

We propose a catalytic cycle using the iodine–dimethylsulfoxide (I2–DMSO) complex for the realization of secondary Mg–O2 batteries. We have demonstrated that the Mg–O2 battery incorporating an I2–DMSO complex electrolyte showed evidence of being rechargeable. [ABSTRACT FROM AUTHOR]

Precise knowledge of the discharge and charge reactions within Li–O2 batteries is an important aspect of developing highly efficient, rechargeable Li–O2 cells. We describe an analytical method capable of determining the quantity of Li2O2 in the cathode on the basis of the reaction of Li2O2 with an oxoammonium salt. [ABSTRACT FROM AUTHOR]

Mg(BH4)(NH2) (I) is prepared by ball milling of a 1:1 molar mixture of Mg(BH4)2 (II) and Mg(NH2)2 followed by annealing. [ABSTRACT FROM AUTHOR]