Search results for "Epos"
showing 10 items of 1649 documents
Perovskite solar cells prepared by flash evaporation
2015
A simple vacuum deposition method for the preparation of high quality hybrid organic-inorganic methylammonium lead iodide perovskite thin films is reported. When sandwiched in between organic charge transporting layers, such films lead to solar cells with a power conversion efficiency of 12.2%.
Processing and adjusting the hydrophilicity of poly(oxymethylene) (co)polymers: nanoparticle preparation and film formation
2016
Handling the insoluble POM: the preparation of nanoparticles based on hyperbranched-linear-hyperbranched ABA triblock copolymers with variable hydrophilicity and composed of short hyperbranched polyglycerol (hbPG) as the A-blocks and linear poly(oxymethylene) (POM) as a B-block is described. The POM-hbPG-nanoparticles with diameters in the range of 190 to 250 nm were generated in a convenient process, combining the solvent evaporation process with the miniemulsion technique, a water borne handling for POM-copolymers. Furthermore, the film formation properties of the nanoparticles were investigated by deposition on silicon and subsequent sintering, which leads to films with a thickness in th…
Fully Vacuum-Processed Wide Band Gap Mixed-Halide Perovskite Solar Cells
2017
Methylammonium lead mixed-halide perovskites MAPb(BrxI1–x)3 are promising materials for the preparation of tandem devices. When exposed to light, MAPb(BrxI1–x)3 segregates in iodide- and bromide-rich phases, limiting the achievable photovoltage and hence the attainable device efficiency. To date only solution-processed mixed-halide perovskites have been demonstrated. We present fully vacuum-deposited mixed-halide perovskite thin films with band gap of 1.72 and 1.87 eV, prepared by controlling the deposition rates of the different halide precursors. When used in thin-film devices, these materials lead to power conversion efficiencies of 15.9 and 10.5%, respectively, which are among the highe…
Combined thermal evaporated and solution processed organic light emitting diodes
2011
Abstract Highly efficient, partly solution processed phosphorescent red, green and white organic light emitting diodes with small molecular weight host materials are prepared from commercially available starting compounds. Starting from an evaporated reference device, layers are stepwise replaced by solution processed layers. Replacing the evaporated hole transport layer by a solution processed polymer interlayer does not affect the performance and allows spincoating of the emissive layer after annealing of the polymer. Devices with, next to the spincoated hole injection and transport layer, a solution processed emission layer show similar characteristics and efficiencies as the reference d…
Growth kinetics of racemic heptahelicene-2-carboxylic acid nanowires on calcite (104).
2016
Molecular self-assembly of racemic heptahelicene-2-carboxylic acid on a dielectric substrate at room temperature can be used to generate wire-like organic nanostructures consisting of single and double molecular rows. By means of non-contact atomic force microscopy, we investigate the growth of the wire-like pattern after deposition by experimental and theoretical means. From analyzing the time dependence of the mean row length, two distinct regimes were found. At the early post-deposition stage, the mean length grows in time. Subsequently, a crossover to a second regime is observed, where the mean row length remains nearly constant. We explain these findings by a mean-field rate equation a…
Production of titanium ion beams in an ECR ion source
2002
Abstract Intensive highly charged Ti ion beams were successfully produced in the 14 GHz ECR ion source at the Accelerator Laboratory, University of Jyvaskyla (JYFL). The Ti beams were produced using the MIVOC technique, i.e. by allowing the vapor of an organic compound containing titanium to diffuse into the ion source at room temperature. After optimizing the source parameters the intensity of the 48 Ti 11+ ion beam reached a value of 45 μA.
Contamination from polycyclic aromatic hydrocarbons (PAHs) in the soil of a botanic garden localized next to a former manufacturing gas plant in Pale…
2010
The Botanical Garden lies within the city of Palermo, a few meters away from one of the largest unused Manufacturing Gas Plant in Sicily. The total concentrations of PAHs (23 compounds) in the soil of Botanical Garden ranged from 947 to 18,072 microg/kg. The wide range of PAH concentrations (RSD=84%) found in the soil samples indicates heterogeneous levels of contamination in the area and this can be explained by considering the different tree distributions which prevents the homogeneous deposition of pollutants on the soil. Soils collected in the Botanical Garden generally showed the highest PAH concentrations, being almost 2-3 times higher than the concentration samples obtained in the ur…
Temporal fatty acid profiles of human decomposition fluid in soil
2017
Abstract We studied the changes in concentration and relative abundance of human-derived fatty acids (FAs) in soil over a period of one year. The study is based on analysis of soil underneath a human body that lay on the soil surface for 18 days before it was discovered. Soil samples were taken when the body was removed, and also 358 days later. Large amounts of the total FA concentration at the start of the measurement period were still present one year after the removal of the body. The FA profile suggested that extensive saturated FA reduction occurred during the first 18 days after deposition. 10-Hydroxystearic acid and FA salts, which are characteristic of adipocere, were abundant in a…
Environmental impact of mining activities on the Hermioni area, Greece
1993
Publisher Summary This chapter investigates the environmental impact of mining activities in the Hermioni area, Greece, including the offshore area. A chemical analysis of sediments associated with diabase lavas in the Hermioni mine area has shown significant enrichments in Fe, Mn, Zn, Cu, and As relative to normal pelagic clays. Marked geographic compositional variations within the Hermioni area have been observed, the highest metal enrichments found at Baroutospelia. Mineralogically the Fe–Mn sediments contain hematite, quartz, and minor amounts of illite, smectites, and feldspars. A chemical analysis of sulfide ore samples showed that the Hermioni ores are Cu-rich pyrites, always contain…
Synthesis and thermal decomposition studies of homo- and heteroleptic tin(iv) thiolates and dithiocarbamates: molecular precursors for tin sulfides
2002
The syntheses and X-ray structures of novel heteroleptic thiolate/dithiocarbamate derivatives (Et2NCS2)2(RS)2Sn (R = Cy, CH2CF3) have been examined and their thermal decompositions compared with those of selected tin(II) and tin(IV) dithiocarbamates. The heteroleptic species decompose to SnS by initial elimination of RSSR to afford (Et2NCS2)2Sn and subsequent loss of [Et2NC(S)]2S. In contrast, (Et2NCS2)4Sn decomposes via [(Et2NCS2)2SnS]2, whose structure has been determined, and finally to SnS2 by sequential elimination of [Et2NC(S)]2S. The two families of compounds, (R2NCS2)4Sn and (Et2NCS2)2(RS)2Sn, thus provide single-source materials for bulk SnS2 and SnS, respectively, by virtue of the…