The Zn(S,O,OH)/ZnMgO buffer in thin‐film Cu(In,Ga)(Se,S)2‐based solar cells part II: Magnetron sputtering of the ZnMgO buffer layer for in‐line co‐evaporated Cu(In,Ga)Se2 solar cells

A ZnS/Zn_1‐xMg_xO buffer combination was developed to replace the CdS/i‐ZnO layers in in‐line co‐evaporated Cu(In,Ga)Se₂(CIGS)‐based solar cells. The ZnS was deposited by the chemical bath deposition (CBD) technique and the Zn_1‐xMg_xO layer by RF magnetron sputtering from ceramic targets. The [Mg]/([Mg] + [Zn]) ratio in the target was varied between x = 0·0 and 0·4. The composition, the crystal structure, and the optical properties of the resulting layers were analyzed. Small laboratory cells and 10 × 10 cm² modules were realized with high reproducibility and enhanced stability. The transmission is improved in the wavelength region between 330 and 550 nm for the ZnS/Zn_1‐xMg_xO layers. Therefore, a large gain in the short‐circuit current density up to 12% was obtained, which resulted in higher conversion efficiencies up to 9% relative as compared to cells with the CdS/i‐ZnO buffer system. Peak efficiencies of 18% with small laboratory cells and 15·2% with 10 × 10 cm² mini‐modules were demonstrated. Copyright © 2009 John Wiley & Sons, Ltd.     

Tuning Memristivity by Varying the Oxygen Content in a Mixed Ionic–Electronic Conductor

The rising interest shown for adaptable electronics and brain‐inspired neuromorphic hardware increases the need for new device architectures and functional materials to build such devices. The rational design of these memory components also benefits the comprehension and thus the control over the microscopic mechanisms at the origin of memristivity. In oxide‐based valence‐change memories, the control of the oxygen drift and diffusion kinetics is a key aspect in obtaining the gradual analog‐type change in resistance required for artificial synapse applications. However, only a few devices are designed with this in mind, as they are commonly built around ionic insulating active materials. This shortcoming is addressed by using a mixed ionic–electronic conductor as functional memristive material. This work demonstrates how the oxygen content in La₂NiO_4+δ (L2NO4), tuned through post‐annealing treatments, has a critical influence on the memory characteristics of L2NO4‐based memristive devices. The presence of interstitial oxygen point defects in L2NO4 affects both its structure and electrical properties. High oxygen stoichiometry in the pristine state leads to an increased electrical conductivity, ultimately resulting in an improved memory window with highly multilevel, analog‐type memory programing capabilities, desirable for analog computing and synaptic applications in particular.     

Merocyanine/C60 Planar Heterojunction Solar Cells: Effect of Dye Orientation on Exciton Dissociation and Solar Cell Performance

In this study the charge dissociation at the donor/acceptor heterointerface of thermally evaporated planar heterojunction merocyanine/C₆₀ organic solar cells is investigated. Deposition of the donor material on a heated substrate as well as post‐annealing of the complete devices at temperatures above the glass transition temperature of the donor material results in a twofold increase of the fill factor. An analytical model employing an electric‐field‐dependent exciton dissociation mechanism reveals that geminate recombination is limiting the performance of as‐deposited cells. Fourier‐transform infrared ellipsometry shows that, at temperatures above the glass transition temperature of the donor material, the orientation of the dye molecules in the donor films undergoes changes upon annealing. Based on this finding, the influence of the dye molecules’ orientations on the charge‐transfer state energies is calculated by quantum mechanical/molecular mechanics methods. The results of these detailed studies provide new insight into the exciton dissociation process in organic photovoltaic devices, and thus valuable guidelines for designing new donor materials.     

Highly Ordered Self‐Assembled Architectures of Modified Terpyridines on Highly Ordered Pyrolitic Graphite Imaged by Scanning Tunneling Microscopy

Scanning tunneling microscopy has been used to study the adsorbed phases of functionalized terpyridines at the solid–liquid interface of highly ordered pyrolitic graphite (HOPG). Terpyridines are well‐known for their complexing behavior to transition metal ions, making them widely used ligands in organometallic and supramolecular chemistry. We found that solutions of 2,2′:6′,2″‐terpyridine‐4′‐oxydodecane (tpy‐O‐C12) and 2,2′:6′,2″‐4′‐oxyoctadecane (tpy‐O‐C18) form highly ordered two‐ dimensional (2D) arrays on HOPG in phenyloctane. For both compounds, large, well‐defined lamellar domains have been observed with domain sizes larger than 500 nm. Sequential scans of an area with two grain boundaries indicate that desorption–resorption is taking place along the domain edges. High‐resolution images of the lamella have been obtained, and the 2D packing within the lamella was determined in detail. The terpyridines align in long uniform double rows with their alkyl chains packing in an alternating, zipper‐like fashion. The terpyridines pack with the polar head‐groups head to head, and the observed size and shape of the molecules fit exactly to their modeled geometries.     

In Situ and Operando Characterization of Proton Exchange Membrane Fuel Cells

For proton exchange membrane fuel cells (PEMFCs) to become a mainstream energy source, significant improvements in their performance, durability, and efficiency are necessary. To improve their durability, there must be a solid understanding of how the structural and electrochemical processes are affected during operation to propose mitigation strategies. To this aim, in situ and operando characterization techniques can locally identify structural and electrochemical processes, which cannot be captured using conventional techniques. Linking these properties in the same geometric area has been challenging due to its inherent limitations, such as sample size and imaging resolution. This has created a knowledge gap in structure‐to‐electrochemical performance relationships as operation and degradation unevenly affect different areas of the cell. In the recent past, catalyst layer degradation, hot spots, and water management have been structurally and electrochemically visualized in the same geometric area, revealing new interactions. To further the research in this direction, these interconnected fields are reviewed, followed by a roadmap for in situ characterization of PEMFCs, treating structural and electrochemical processes as a unified subject. With this approach, the knowledge of the degradation of PEMFCs will be significantly improved.     

Quantum mechanics as quantum information,mostly

Abstract

In this paper, I try to cause some good-natured trouble. The issue is, when will we ever stop burdening the taxpayer with conferences devoted to the quantum foundations? The suspicion is expressed that no end will be in sight until a means is found to reduce quantum theory to two or three statements of crisp physical (rather than abstract, axiomatic) significance. In this regard, no tool appears better calibrated for a direct assault than quantum information theory. Far from a strained application of the latest fad to a time-honoured problem, this method holds promise precisely because a large part—but not all—of the structure of quantum theory has always concerned information. It is just that the physics community needs reminding.     

Secondary organic aerosol formation from the photooxidation of p- and o-xylene

The formation of secondary organic aerosol (SOA) from the photooxidation of xylene isomers (m-, p-, and o-xylenes) has been extensively investigated. The dependence of SOA aerosol formation on the structure of xylene isomers in the presence of NO was confirmed. Generally, SOA formation of p-xylene was less than that of m- and o-xylenes. This discrepancy varies significantly with initial NOx levels. In a NOx-free environment, the difference of aerosol formation between o- and p-xylenes becomes insignificant. Several chemical pathways for the SOA dependence on structure and NOx are explored, with the experimental findings indicating that organic peroxides may be a major key to explaining SOA formation from aromatic hydrocarbons.     

The involvement of oxidative stress in ochratoxin A and fumonisin B1 toxicity in rats

The aim of this study was to find out whether very low doses of nephrotoxic and hepatotoxic mycotoxins ochratoxin A (OTA) and fumonisin B1 (FB1) induce oxidative stress in rat kidney and liver and whether their effect is synergistic. Rats were treated orally with OTA (5 ng/kg b.w. and 50 microg/kg b.w.) and FB1 (200 ng/kg b.w. and 50 microg/kg b.w.), or their combinations. Malondialdehyde (MDA) and protein carbonyls (PCs) concentration in kidney was affected with lower dose of OTA than in liver (p<0.05). FB1 did not affect MDA and PCs concentrations in the liver, while in the kidney both FB1 doses increased MDA concentration (p<0.05). The combination of the lower doses of OTA+FB1 increased the MDA and PCs concentration both in the liver and the kidney, compared to controls and animals treated with respective doses of mycotoxins (p<0.05). The combinations of mycotoxins reduced the catalase activity only in the kidney when compared to controls (p<0.05). In contrast to the increased kidney concentrations of MDA and PCs even with very low doses of OTA and FB1, the activity of catalase and SOD does not change. Combinations of OTA+FB1 affected almost all parameters, which indicates their potential to produce oxidative damage.     

Performance of new clean-up column for the determination of ochratoxin A in cereals and foodstuffs by HPLC-FLD

The performance of the newly developed Mycosep® 229 Ochra and Multisep® 229 Ochra clean-up columns for ochratoxin A (OTA) determination was evaluated. OTA was subsequently analysed using RP-HPLC with fluorescence detection. Recoveries for frequently contaminated commodities, like cereals, red wine, raisins and green coffee, were estimated. The recoveries obtained for the Mycosep 229 Ochra column were in the range from 87.9 ± 12.5% (n = 6) for wheat to 99.4 ± 2.7% (n = 24) for raisins. For Multisep 229 Ochra, recoveries from 76.5 ± 8.0% (n = 6) for barley to 86.4 ± 1.4% (n = 24) for raisins were achieved. Limits of detection for all matrices investigated (maize, wheat, rice, barley, raisins, green coffee beans, red wine) were in the range 0.4-2.4 μg kg^-1. The trueness of the method was tested using a certified reference material.