The design and outdoor application of dye-sensitized solar cells

To upscale DSC size to commercial size, our group was involved in developing a commercial DSC panel, which could show the industrial way and prospect. The repeatable DSC module with the size of 150 mm × 200 mm and photoelectric conversion efficiency around 6% was reproduced in our laboratory. The DSC panel up to the size of 450 mm × 800 mm was fabricated. This is the high efficiency and industrial production design of a DSC panel, a primary power station with 500 W was installed on our roof for charging the battery. The study on the stability and performance of the DSC module, panel and future production are ongoing in our laboratory. In this article, we will report a systematic study in the test and the design from the single cell, the modules, to the panels, and our design of a 500 W primary DSC power station.     

Retardation of senescence by low temperature and benzyladenine in intact primary leaves of soybean

Effects of temperature and benzyladenine (BA) on the senescenceof intact primary leaves of soybean were investigated. Comparedwith high temperature (30?C for day and 25?C for night), lowtemperature (15?C for day and 13?C for night) significantlyretarded senescence of intact primary leaves. Repeated dailytreatment of the primary leaves with BA (200 mg/liter) beginning15 days after growth at high temperature resulted in retardationof the senescence process. The lower activity of cytokininsin the primary leaves of seedlings grown under high temperaturemay be responsible for rapid senescence. (Received January 14, 1980; )     

Retardation of inflorescence development inCalendula officinalis by a morphactin and its application

The morphactin - chlorflurenol at 1, 5, 25, 125 and 625 μg/plant either caused total damage of the shoot apices or allowed a few inflorescences to develop with few or no flowers. The inflorescences arising in the lateral branches showed suppressed bracts and modified flowers. With time the treated plants recovered and showed a significant increase in the growth of laterals and the number of inflorescences. Thus morphactin can be used for prolonging the growth period and for obtaining more wholesome plants.     

Rapid synthesis of bis (2,2′-bipyridine) nitratocopper(II) nitrate using a hydrothermal method and its application to dye-sensitized solar cells

In this study we synthesized bis (2,2′-bipyridine) nitratocopper(II) nitrate in order to examine its the crystal structure, optical property and application to dye-sensitized solar cells (DSSCs). Single X-ray analysis results revealed that the acquired complex exhibited five-coordination with four nitrogen atoms of bipyridine and the oxygen bond of the ion. The reflectance UV-Vis absorptions showed three absorptions that were assigned to ligand-to-ligand at around 230-350 nm, metal-to-ligand charge transfer at around 350-600 nm, and d-d transfer at around ∼650 nm. Cyclic voltammetry in acetonitrile revealed a reversible Cu(I) → Cu(II) oxidation process at a highest occupied molecular orbital (HOMO) and a lowest unoccupied molecular orbital (LUMO) levels of −4.692 and −4.071 eV, respectively. The photoelectric efficiency in DSSCs was approximately 0.032% with the nanometer-sized TiO₂ in the condition of an open-circuit voltage (V_oc) of 0.346 V, a short-circuit current density (J_sc) of 0.166 mA/cm² at an incident light intensity of 100 mW/cm².     

Getting to guanine: mechanism and dynamics of charge separation and charge recombination in DNA revisited.

The mechanism and dynamics of charge separation and charge recombination in synthetic DNA hairpins possessing a stilbenedicarboxamide linker and a single guanine-cytosine base pair have been reinvestigated. The combination of femtosecond broad-band pump probe spectroscopy, nanosecond transient absorption experiments, and picosecond fluorescence decay measurements permits analysis of the formation and decay of the stilbene anion radical. Reversible hole injection resulting in the formation of the stilbene-adenine contact radical ion pair is found to occur on the picosecond time scale. The mechanism for charge separation across two or more base pairs is revised from single step superexchange to a multi-step process: hole injection followed by hole transport and hole trapping. The mechanism of charge recombination remains assigned to a superexchange process.     

Biological inactivation of adhering Listeria monocytogenes by listeriaphages and a quaternary ammonium compound.

The use of listeriaphages as a means of disinfecting contaminated stainless-steel and polypropylene surfaces was investigated. Surfaces artificially contaminated with L. monocytogenes 10401 and 8427 were sanitized with suspensions of listeriaphages (H387, H387-A, and 2671), all belonging to the Siphoviridae family. Phage suspensions at concentrations of up to 3.5 x 10(8) PFU/ml were at least as efficient as a 20 ppm solution of a quaternary ammonium compound (QUATAL) in reducing L. monocytogenes populations. A synergistic activity was observed when two or more phages were used in combination and when phages were suspended in QUATAL. The biological activity of the three phages was not affected by QUATAL concentrations of 50 ppm and a contact time of 4 h.     

Gel electrophoresis of partially denatured DNA. Retardation effect: its analysis and application.

The hypothesis about the role of partial denaturation in DNA retardation during its electrophoresis in denaturing gel /1,2/ was tested. We used partially melted DNA molecules in which the size of the melted regions and their location were known. They were obtained through glyoxal treatment of the melted regions by a procedure allowing the denatured state to be fixed at any point within the melting range. The approach and the availability of the melting maps of DNAs made it possible to investigate DNA molecules differing in length and in the size of the melted regions. The presence of a denatured region at the end of the molecule or inside of it was shown to decrease its electrophoretic mobility, the effect depending on the size of the melted region and on the DNA length. On the basis of the experimental results an explanation is proposed for the cause of retardation in the case of partially denatured DNA.     

Improvement of photovoltaic performance by substituent effect of donor and acceptor structure of TPA-based dye-sensitized solar cells

We report a computational study of a series of organic dyes built with triphenylamine (TPA) as an electron donor group. We designed a set of six dyes called (TPA-n, where n?=?0–5). In order to enhance the electron-injection process, the electron-donor effect of some specific substituent was studied. Thus, we gave insights into the rational design of organic TPA-based chromophores for use in dye-sensitized solar cells (DSSCs). In addition, we report the HOMO, LUMO, the calculated excited state oxidized potential E^dye*(eV) and the free energy change for electron-injection ΔG_inject(eV), and the UV-visible absorption bands for TPA-n dyes by a time-dependent density functional theory (TDDFT) procedure at the B3LYP and CAM-B3LYP levels with solvent effect. The results demonstrate that the introduction of the electron-acceptor groups produces an intramolecular charge transfer showing a shift of the absorption wavelengths of TPA-n under studies.

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Graphical Abstract Several organic dyes TPA-n with different donors and acceptors are modeled. A strong conjugation acrros the donor and anchoring groips (TPA-n) bas been studied. Candidate TPA-3 shows a promising results.

     

Key aspects of individual layers in solid-state dye-sensitized solar cells and novel concepts to improve their performance

In this feature article, we discuss the key aspects of solid-state dye-sensitized solar cells (SDSC) and propose different concepts based on extensive studies carried out in our group to improve their performance. The influence of compact TiO₂ layer, novel donor-antenna sensitizing dyes, nature of nanocrystalline-TiO₂ layers and solid-state organic hole conductors on the performance of SDSC is discussed in this article. Both preparation and thickness of the compact TiO₂ layer were optimized using spray pyrolysis. The studies revealed that an optimum film thickness of 120-150 nm of compact TiO₂ yielded the best rectifying behavior and SDSC performance. The influence of three different mesoporous titania films, obtained from three different titania nanocrystals, prepared by sol-gel, thermal, and colloidal-microwave process, was also studied and discussed here. The TiO₂ layer with the optimum pore volume and pore diameter (∼44 nm) displayed the highest efficiency and IPCE in SDSC. The importance of pore size rather than high surface area for filling the mesoporous layer with solid-state hole conductor became evident from this study. A series of heteroleptic Ru(II) complexes carrying donor antenna moieties, namely, triphenylamine (TPA) or N,N′-bis(phenyl)-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD), were synthesized and applied in SDSC. These novel donor-antenna dyes revealed spectacular performances of power conversion efficiencies in the range 1.5-3.4%, as measured under AM 1.5 spectral conditions. This was attributed to highly efficient light harvesting of these novel dyes and the improved charge-transfer dynamics at TiO₂-dye and dye-hole conductor interfaces. Different low molecular weight and polymeric triphenyldiamines were synthesized and utilized as hole-transporting layers (HTL) in SDSC. Different studies showed that low molecular TPDs displayed better efficiency than polymeric counterparts due to their improved filling into the pores of nc-TiO₂ layer. Another interesting study revealed that an optimum driving force in terms of HOMO-level difference between the dye and HTL decides charge carrier generation efficiency. Recently, novel hole conductors with spiro-bifluorene-triphenylamine core for transporting holes and tetraethylene glycol side chains for binding lithium ions were synthesized and applied in SDSC. This work clearly emphasizes that Li⁺-salt is required at the TiO₂/dye interface as well as in the bulk of HTL. It was also found that the addition of about 5-20% of these Li⁺-binding hole conductors and higher Li-salt (N-lithiotrifluoromethane sulfonamide) concentrations improved the SDSC performance. An improvement of about 120% in the solar cell efficiency as compared to the reference cells was achieved with an optimum composition of Li⁺-binding hole conductor and Li-salt.     

Cost-benefit analysis of recombination and its application for understanding of chiasma interference.

A cost-benefit analysis of recombination was undertaken. The beneficial effects of crossing-over are proportional to the frequency of recombinant offspring, while its harmful effects (errors of crossing-over leading to mutations) are proportional to the number of crossover exchanges. An equilibrium point should exist where the beneficial effects of crossing-over are balanced by its harmful effects. It is suggested that natural selection sustains a number of crossover exchanges per meiosis at the level that provides highest benefit-cost difference. Chiasma interference prevents the arising of closely located exchanges which are less effective in the production of recombinants than exchanges separated by some "interference distance". Computer simulation shows that chiasma interference increases the recombination effectiveness of the multiple crossover exchanges as compared to the case without interference.     

Production of a novel bioflocculant by Bacilluslicheniformis X14 and its application to low temperature drinking water treatment

A novel bioflocculant ZS-7 produced by Bacillus licheniformis X14 was investigated with regard to its synthesis and application to low temperature drinking water treatment. The effects of culture conditions including pH, carbon source, nitrogen source, temperature, inoculum size and shaking speed on ZS-7 production were studied. The purified bioflocculant was identified as a glycoprotein consisting of polysaccharide (91.5%, w/w) and protein (8.4%, w/w), with an approximate molecular weight of 6.89 × 10⁴ Da. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) indicated the presence of amino, amide, carboxyl, methoxyl and hydroxyl groups. This bioflocculant showed good flocculating performance and industrial potential for treatment of low temperature drinking water, and the maximum removal efficiencies of COD_Mn and turbidity were 61.2% and 95.6%, respectively, which were better than conventional chemical flocculants. Charge neutralization and bridging were proposed as the reasons for the enhanced performance based upon the experimental observations.