Preparation of Quantum-Dot Sensitized Solar Cells Using Aqueous Solution Processes

Photographic and photogrammetric records of the emerged rocks at Rocas Alijos are of interest on several accounts: First, the relatively young age of the emerged rocks at Rocas Alijos implies relatively rapid erosion. Furthermore, the loose, blocky nature of the material, and the complete disappearance of the fourth rock pictured in the etching from the 1837 Venus expedition (Skinner and Schmieder, 1996), suggest that the erosion is intermittent. Rather than a constant slow removal of material by aqueous solution, salt heaving, and similar microscopic processes, it is likely that major mass loss occurs by intermittent failure of joints or supports, resulting in sporadic sudden failure and collapse, perhaps stimulated by periods of violent weather or earthquakes. Human agents, such as aerial bombardment, may have been a significant factor historically. Thus, a photographic record could enable tracking of these events and thereby an estimation of the projected life of the structures.

Monolayered nanodots of titanium, tungsten, and manganese oxides were obtained by exfoliation of the nanocrystals through aqueous solution processes at room temperature. The precursor nanocrystals of the layered compounds, such as sodium titanate (Na(0.80)Ti(1.80)□(0.2)O4·xH2O, □: vacancy (x < 1.17)), cesium tungstate (Cs4W11O35·yH2O (y < 10.5)), and sodium manganate (Na0.44MnO2·zH2O (z < 0.85)), were synthesized in an aqueous solution. These nanocrystals of the layered compounds were delaminated into the monolayered nanodots through introduction of a bulky organic cation in the interlayer space. The resultant monolayered nanodots of the titanate and tungstate 2-5 nm in lateral size showed a remarkable blueshift of the bandgap energies. The calculation studies supported the blueshifts of the bandgap energies. The results suggest that syntheses of monolayered nanodots can expand the tuning range of the properties based on size effect. The present approaches for generation of ultrathin tiny objects can be applied to a variety of nanomaterials.

A comparison is made of the oil recovery efficiency obtained by injecting surface active agents in an oil phase vehicle vs. injecting these agents in an aqueous phase vehicle. Mobilities and mobility ratio of the flowing phases, sensitivity of the micellar slug and phases, sensitivity of the micellar slug and polymer solution to reservoir brine, mechanism polymer solution to reservoir brine, mechanism of oil bank formation, slug sizes used for each process, and adsorption of surfactant from the process, and adsorption of surfactant from the micellar slugs are considered in this analysis. Also discussed are 1) the importance of phase relationships between the crude oil, brine and injected surfactant-solvent on process performance, and 2) the effect on oil recovery efficiency of preflushing the rock prior to a micellar-polymer preflushing the rock prior to a micellar-polymer flood. Introduction The Miscellar-polymer processes used to recover oil from watered-out reservoirs can be classified under two primary categories. In one, the surface active agents are injected primarily in an oil phase vehicle, and in the other, an aqueous phase vehicle is used. The compositions of the slugs used in the two processes are shown on the generalized phase diagram (FIGURE 1). A given oil, water, and surfactant system can produce aqueous, water-external, oil-external, or bicontinuous phase, micellar solutions. However, there are distinct differences in the oil displacement performance of the solutions; these difference are performance of the solutions; these difference are described below. MICELLAR SLUG Mobility FIGURE 1 shows the viscosities of typical oil-in-water and water-in-oil microemulsions, and aqueous micellar solutions, as a function of oil and water content. The soluble oils, or oil-external systems, are characterized by the presence of enough oil to maintain a high viscosity over a rang of water content from 0 to 70%. Consequently, the micellar slug used in these processes has a viscosity sufficiently high to immediately create, and to maintain, a favorable mobility ratio between slug and the low mobility, oil-water bank which it mobilizes in the reservoir. This favorable mobility ratio minimizes dispersion of the slug. By contrast, the aqueous micellar solutions, as injected, contain less than 5% oil and have low viscosities. In properly designed aqueous slugs, the eventual formation of microemulsions, which occurs in-situ with the residual oil in the reservoir, tends to increase the viscosity of the micellar slug. However, the mobility ratio that prevails during at least the initial stages of the flood is unfavorable, and a portion of the micellar slug tends to bypass the oil bank which may be formed by the slug. Even in linear laboratory systems the lack of initial mobility control appears to be reflected in lower oil recovery efficiency as shown by comparison of the first two floods listed on TABLE 1. Flood No. 2 was identical to Flood No. 1 except that the oil was left out of the micellar slug causing the aqueous slug to have a viscosity of only 5 cp. A larger decrease in oil recovery efficiency is likely to occur in the reservoir due to lack of mobility control because of unbounded radial flow and permeability variations. Aqueous micellar systems often rely upon the addition of polymer to the slug to attain the proper initial slug viscosity. However, the presence of polymer in a slug has the negative effect of making the phase relationships with oil and water less favorable (larger two-phase area) and thereby decreasing oil recovery efficiency. FIGURE 2 shows the ternary phase relationships for oil-surfactant-brine systems with and without polymer present in the brine. As shown in this figure, the addition of polymer causes a large increase in the two-phase area where appreciable oil is present. TABLE 1 presents data (Floods 2–5) which show the adverse effects on oil recovery of adding polyacrylamide polymer (Cyanatrol 9SOS) to two different aqueous micellar slugs. The economics of using polymer rather than oil in the slug are not a simple trade-off.

Additionally to residual ozone, in processed aqueous solutions using intense electric fields, free radicals are present and determines changes of a variety of physical parameters—chemical of solutions. Ozone and free radicals remaining in the aqueous treatment processes are primarily responsible for harmful inhibiting, but also are useful for biostimulation processes of living environments (increasing the speed action of polymorphonuclear leukocytes in the healing of severe infections, changes of the pattern of collagen regeneration during ulcerations healing). This paper presents the results of a multidisciplinary research, with extensive scientific and technical aspects. Intense electric fields, especially using corona point or filiform discharge electrodes, used in specially designed treatment cells and the processes of air ionization, generates and trains a variety of electrical charge carriers, which have sufficient energy in order to brake different gas molecules, in order to produce oxygen, or to determine the generation of ozone and free radicals in retention solutions or in the present environment. The electric field parameters, the intensity, the nature and shape of high voltage, exposure time, but also the characteristics and structure of cell treatment (multipoint, filiform or brush type electrodes), gap size or the step between the discharge electrodes, all are important parameters which determines the presence and concentration of ozone and free radicals which, present in the processed aqueous solutions.

Recent attention on the lanthanides (Ln) contaminant such as lanthanum (La) and neodymium (Nd) extensively used in industry has aroused the great desire for the effective adsorbent. Biochar, relying on its high selectivity and optional ease, is regarded as a promising adsorbent for lanthanides removal although the evaluation of the efficiency and mechanism of La(III) and Nd(III) adsorption on biochar still lags. Here, we investigated the aqueous adsorption processes through SEM, TEM, EDS, FTIR and Raman spectra, XPS, and batch experiments. The porous structure of biochar and the complex functional groups on its surface contributed to the La(III) and Nd(III) removal processes. The kinetic of La(III) and Nd(III) adsorption agreed well with the pseudo-second-order kinetic model. The adsorption capacity showed a strong positive correlation with pH value. However, it was only slightly altered and robust in La(III) and Nd(III) adsorption respectively. The isotherm results reflected significant fitting to the Sips model as well as Langmuir and Freundlich model. Thermodynamic demonstrated the spontaneity, endothermic nature, and temperature favor of the adsorptions on biochar surface (La: ΔH0=35.39 (kJ/Mol), ΔS0=104.71(J*Mol-1*K-1) and ΔG0<0; Nd: ΔH0=16.71(KJ/mol), ΔS0=119.41(J*Mol-1*K-1) and ΔG0<0). Both the La(III) and Nd(III) removal processes combined physical and chemical adsorptions. Therefore, biochar could be a potential green material for the lanthanum and neodymium adsorption with high efficiency.

Organic compounds such as amino acids may have been delivered to the early Earth via carbonaceous chondrites and interplanetary dust particles. Mineralogical and petrological evidence has shown that liquid water was formed from water ice in the early stages of the formation of the parent bodies of carbonaceous chondrites, due to the heat from the radioactive decay of short-lived radionuclides such as 26Al. In previous research, amino acid precursors were produced from aqueous solutions containing formaldehyde and ammonia by hydrothermal experiments and gamma-ray irradiation experiments to evaluate organic formation during aqueous alteration processes in meteorite parent bodies. However, the differences in the effects and reactions of gamma rays and heating, as well as the synergetic effects, are not well understood. In this study, both heating and gamma irradiation were applied to aqueous solutions containing formaldehyde, methanol, and ammonia to investigate the synergistic effects of heating and gamma rays on amino acid formation. The results showed that gamma irradiation followed by heating was more efficient in producing amino acid precursors compared to heating followed by gamma irradiation. The characteristic features of UV-visible and fluorescence spectra of the experimental products were consistent with Maillard-type reactions, suggesting that Maillard-type reactions led to the formation of amino acid precursors.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotoelectrochemical evolution of elemental fluorine at titanium dioxide electrodes in anhydrous hydrogen fluoride solutionsChong Mou. Wang, Qui Chee. Mir, Simin. Maleknia, and Thomas E. MalloukCite this: J. Am. Chem. Soc. 1988, 110, 11, 3710–3712Publication Date (Print):May 1, 1988Publication History Published online1 May 2002Published inissue 1 May 1988https://pubs.acs.org/doi/10.1021/ja00219a084https://doi.org/10.1021/ja00219a084research-articleACS PublicationsRequest reuse permissionsArticle Views236Altmetric-Citations12LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

水溶液プロセスによる酸化亜鉛ナノロッドアレイの製膜

Chapter 15 - Nanostructuring of Metal Oxides in Aqueous Solutions

Spherical polycrystalline particles of Na4Zr2Si3O12 (NZS) have been prepared by a mist pyrolysis technique with alkoxide ethanol solution. Firing the precursor particles, obtained by pyrolysing at 550 °C, yielded the NZS with the highest S/N ratio and the least second phase at ∼ 1000 °C. Each spherical particle with an average size of ∼ 0.5 μm was composed of primary particles of 0.1 μm diameter after firing. Comparing the particle formation process with the sol-gel, alkoxide pyrolysis and the aqueous solution processes, it would appear that the primary particle size of the mist-pyrolysed NZS depends on the size and residual alkyl group content of the precursor polymers.

Organic bulk-heterojunction (BHJ) solar cells are highly efficient solar cells with additional advantages such as low-cost production, large area, and mechanical flexibility, as they can be fabricated by solution processing without using high vacuum equipment [1]. On the other hand, an extremely high PCE of 7.5% has recently been reported for BHJ solar cells by Murray et al. [2]. The cells were fabricated using a p-type semiconductor, poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7), an n-type semiconductor, [6,6]-phenyl-C71-butyric-acid-methyl-ester (PC71BM), and a lithium fluoride (LiF) inserted Al cathode on an indium tin oxide (ITO) coated glass substrate. These promising results inspired many recent studies on BHJ solar cells based on PTB7:PC71BM, and various techniques were proposed to further improve the performance of the BHJ solar cells. Ternary or quaternary blend solar cells have also been reported to exhibit interesting performances. Lin et al. [3] have demonstrated a significant improvement in PCE by adding the PTB7 polymer to a poly[[4,8-bis[(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-bnodithiophene-2,6-diyl]] (PCD TBT):PC71BM host system in order to form a ternary-blend BHJ solar cell; the addition of 5 wt% of PTB7 resulted in the greatest PCE improvement. Such studies on ternary-blend solar cells showed performance improvements as a result of adding minute amounts of additives to the host active layers. Ohori et al. recently reported significant improvements in the performance of BHJ solar cells based on ternary-blend organic semiconductor materials with smaller amounts of P3HT additives into the PTB7:PC61BM active layers [4]. They suggested that the improvement of their solar cells was due to enhanced carrier transport paths. Xu et al. reported a significant increase in the open-circuit voltage (Voc) of quaternary-blend BHJ solar cells based on P3HT as a donor, and PC61BM, indene-C60 bisadduct (ICBA) and silicon phthalocyanine bis(trihexylsilyl oxide) as acceptors [5]. Cheng et al. fabricated ternary blend BHJ solar cells based on PTB7:ICBA:PC71BM, and found that the solar cells showed the maximum PCE at the ICBA weight fraction of 15% of the total weight of ICBA and PC71BM [6]. They suggested that the PCE improvement was due to the cascade electron transfer through the lowest unoccupied molecular orbital (LUMO). Notably, ternary blend solar cells based on PTB7, PC61BM, and PC71BM may have similar LUMO cascade structures, but they have not yet been reported. In this paper, we report on BHJ solar cells based on ternary blend solutions of PTB7, PC71BM, and PC61BM. Bulk-heterojunction solar cells were fabricated using ternary blend dichlorobenzene solutions of poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7):[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM):[6,6]-phenyl C71 butyric acid methyl ester (PC71BM) with different weight ratios between PC61BM and PC71BM. In all the solar cells, the overall weight ratio of polymer to fullerene was maintained at 1:1.5, while the composition of the fullerene component (PC61BM:PC71BM) was varied. The ultraviolet-visible absorption spectra of these ternary blend films showed that the photon absorptions at wavelengths between 300 and 800 nm continuously decreased with the increase of the PC61BM weight fraction in the PC61BM and PC71BM total weight. The measurement results of the solar cell performance showed that the open-circuit voltage notably increased for PC61BM weight fractions between 10% and 90%, while it decreased at 100%. The short-circuit current showed the most significant increase in the PC61BM weight fraction range between 50% and 60%. A power conversion efficiency of 3.4% was achieved when the PC61BM weight fraction was between 50% and 60%. These results may suggest that the transport of the photoexcited electrons between the cathode and the PC61BM/PC71BM nanodomains was enhanced. [1] C. J. Brabec, N. S. Sariciftci, and J. C. Hummelen, Adv. Funct. Mater., 11 (2001) 15. [2] I. P. Murray, S. J. Lou, L. J. Cote, S. Loser, C. J. Kadleck, T. Xu, J. M. Szarko, B. S. Rolczynski, J. E. Johns, J. Huang, L. Yu, L. X. Chen, T. J. Marks, and M. C. Hersam, J. Phys. Chem. Lett., 2 (2011) 3006. [3] R. Lin, M. Wright, B. P. Veettil, and A. Uddin, Synth. Met., 1927 (2014) 113. [4] Y. Ohori, S. Fujii, H. Kataura, and Y. Nishioka, Jpn. J. Appl. Phys., 45 (2015) 04DK09. [5] H. Xu, H. Ohkita, H. Benten, and S. Itoh, Jpn. J. Appl. Phys., 53 (2014), 01AB10. [6] P. Cheng, Y. Li, and X. Zhan, Energy Environ. Sci., 7 (2014) 2005.

Diversifying Progress in Solar

Pristine fullerenes mixed by vacuum-free solution process: Efficient electron transport layer for planar perovskite solar cells

Water/alcohol-soluble conjugated polymers (WSCPs) and small molecules (WSCSs) are materials that can be processed from water or other polar solvents. They provide good opportunities to fabricate multilayer organic optoelectronic devices without interface mixing by solution processing, and exhibit a promising interface modification ability for metal or metal oxide electrodes to greatly enhance the device performance of solar cells. Moreover, owing to their intriguing processability, WSCPs and WSCSs have great potential for applying environmentally friendly processing technologies to fabricate solar cells. In this review, the authors give an overview of recent developments in WSCPs and WSCSs, including their molecular design, material synthesis, functional principles and application as interface modification layers and photoactive components in emerging photovoltaic technologies such as organic/polymer solar cells, organic-inorganic hybrid solar cells and dye-sensitised solar cells.

PSS) on nanostructures. Here we demonstrate low-pressure-assisted coating method of PSS on surface-modified silicon nanotips with broadband light-trapping characteristics to improve interface property and to achieve high-efficiency hybrid solar cells through a solution process. The approach enhances the effective minority-carrier lifetime and the coverage of PSS on the surface of nanostructures. Hybrid solar cells fabricated with surface-modified nanotips exhibit a high fill factor of 70.94%, short-circuit current density of 35.36 mA/cm(2), open-circuit voltage of 0.528 V, and power conversion efficiency of 13.36%. The high efficiency and the high fill factor are achieved because of conformal coating of PSS via a low-pressure-assisted coating process, excellent light harvesting without sacrificing the minority-carrier lifetime, and efficient charge separation/collection of photogenerated carriers.