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The way to predict outdoor lifetime
No full textThe operational stability of perovskite solar cells is often tested in the laboratory environment but its correlation to real world operation is still unclear. New research shows that the outdoor ageing behaviour of the devices can be modelled with temperature dependent degradation rates from laboratory stability tests that apply both heat and light stressor
Improved Air Stability of Tin Halide Perovskite Solar Cells by an N Type Active Moisture Barrier
Get PDFTin halide perovskite solar cells are promising for the next generation of highly efficient photovoltaics. Their commercialization can be accelerated by increasing their stability in moisture and oxygen. Herein, an n type organic molecule IO 4Cl is applied as an interlayer between the perovskite films and electron transport layers in p i n structured devices. The electron rich indacenodithieno [3,2 b]thiophene enhances electron transport, while the hydrocarbon side chains and rigid conjugated backbone isolate air. It is also shown that the C amp; 9552;O in IO 4Cl can coordinate with Sn2 on perovskite films surface and grain boundaries to enhance perovskite crystal stability. In addition, IO 4Cl slows down crystallization dynamics, resulting in lower non radiation recombination. The moisture ingress in the perovskite films is tracked under high relative humidity RH and it is found that IO 4Cl can mitigate moisture infiltration. Finally, the devices with IO 4Cl maintain 95 of the initial power conversion efficiency after 1200 h of storage in a nitrogen filled glovebox, and their stability in ambient air 60 80 RH is significantly improved against pristine devices, thus demonstrating the beneficial effects of IO 4Cl interlayer on device stabilit
Toward magneto plasmonic functionality in a self assembled device based on colloidal synthesis
Get PDFThe confinement of surface plasmon polaritons SPPs offers strong field strengths also for longitudinal field components. Phenomena like spin momentum locking can thus be exploited for novel functionality in nanodevices. External control of transport or directional coupling of propagating SPPs would be highly interesting for applications. Herein, the coupling of noble metal and magnetic nanoparticles to a silver nanowire acting as SPP waveguide using a hybrid self assembly approach is demonstrated. A designated setup is reported to isolate and investigate magnetically controlled transport in such devices. Various configurations are measured to quantify the required sensitivity for the typically tiny magnet response at moderate strengths of the magnetic field. Although magnetic control cannot be achieved, the required improvements can be estimated based on a heuristic numerical model. It is suggested using an approach to enhance magnetic response using a combination of metal and magnetic nanoparticles. Such devices can be assembled in principle with self assembly approach in a multistep proces
Trapping of a phenoxyl radical at a non haem high spin iron II centre
No full textThe activation of dioxygen at haem and non haem metal centres, and subsequent functionalization of unactivated C amp; 8210;H bonds, has been a focal point of much research. In iron mediated oxidation reactions, O2 binding at an iron II centre is often accompanied by an oxidation of the iron centre. Here we demonstrate dioxygen activation by sodium tetraphenylborate and protons in the presence of an iron II complex to form a reactive radical species, whereby the iron oxidation state remains unaltered in the presence of a highly oxidizing phenoxyl radical and O2. This complex, containing an unusual iron II phenoxyl radical motif, represents an elusive example of a spectroscopically characterized oxygen derived iron II reactive intermediate during chemical and biological dioxygen activation at haem and non haem iron active centres. The present report opens up strategies for the stabilization of a phenoxyl radical cofactor, with its full oxidizing capabilities, to act as an independent redox centre next to an iron II site during substrate oxidation reaction
Reference free x ray fluorescence analysis with a micrometer sized incident beam
No full textSpatially resolved x ray fluorescence XRF based analysis employing incident beam sizes in the low micrometer range amp; 956;XRF is widely used to study lateral composition changes of various types of microstructured samples. However, up to now the quantitative analysis of such experimental datasets could only be realized employing adequate calibration or reference specimen. In this work, we extent the applicability of the so called reference free XRF approach to enable reference free amp; 956;XRF analysis. Here, no calibration specimen are needed in order to derive a quantitative and position sensitive composition of the sample of interest. The necessary instrumental steps to realize reference free amp; 956;XRF are explained and a validation of ref. free amp; 956;XRF against ref. free standard XRF is performed employing laterally homogeneous samples. Finally, an application example from semiconductor research is shown, where the lateral sample features require the usage of ref. free amp; 956;XRF for quantitative analysi
Direct Spectroscopic Confirmation of the Oxygen Centered Diradical Character of the Tetraoxidorhenium VII Cation [Re O 4]
Get PDFMononuclear inorganic diradical species are scarce. Here, we confirm, via X ray absorption spectroscopy in the gas phase combined with computational studies, the oxygen centered diradical character of the tetraoxidorhenium VII cation. A dioxido superoxido isomer, close in energy to the diradical, is also found, where rhenium appears in its rare oxidation state of 6. Addition of one or two hydrogen atoms to [Re,O4] forms hydroxido ligands, and strongly disfavors isomers with any oxygen oxygen bond. This adds spectroscopic characterization of the rhenium oxidation state and the nature of ligands to the known ability of [Re,O4] to perform two consecutive hydrogen atom abstraction reactions from methane, and demonstrates that pentaatomic [Re,O4] combines a metal center in its highest oxidation state with two oxygen centered radical ligands in a highly reactive specie
Enhanced quantum properties of shallow diamond atomic defects through nitrogen surface termination
No full textNitrogen vacancy NV centers in diamond have emerged in recent years as leading quantum sensors in various modalities. Most applications benefit from shallow NVs, enabling higher sensitivity and resolution. However, near surface NVs lt; 20 nm depth suffer from reduced stability and coherence properties due to additional noise. We demonstrate a novel surface termination technique based on nitrogen plasma under non damaging conditions, achieving significant improvement in NV optical stability and quantum coherence. X ray characterization of the nitrogen terminated diamond surface suggests limited charge transfer between the NV centers and surface electronic states compared to oxygen terminated diamon
Crystal structure of blue laccase BP76, a unique termite suicidal defense weapon
No full textAging workers of the termite Neocapritermes taracua can defend their colony by sacrificing themselves by body rupture, mixing the externally stored blue laccase BP76 with hydroquinones to produce a sticky liquid rich in toxic benzoquinones. Here, we describe the crystal structure of BP76 isolated from N. taracua in its native form. The structure reveals several stabilization strategies, including compact folding, glycosylation, and flexible loops with disulfide bridges and tight dimer interface. The remarkable stability of BP76 maintains its catalytic activity in solid state during the lifespan of N. taracua workers, providing old workers with an efficient defensive weapon to protect their colon
Insights into a Defective Potassium Sulfido Cobaltate Giant Magnetic Exchange Bias, Ionic Conductivity, and Electrical Permittivity
Get PDFThe novel potassium sulfido cobaltate, K2[Co3S4] is introduced, with 25 vacancies of the cobalt positions within a layered anionic sublattice. The impedance and dielectric investigations indicate a remarkable ionic conductivity of 21.4 mS cm amp; 8722;1 at room temperature, which is in the range of highest ever reported values for potassium ions, as well as a high electrical permittivity of 2650 at 1 kHz, respectively. Magnetometry results indicate an antiferromagnetic structure with giant intrinsic exchange bias fields of 0.432 and 0.161 T at 3 and 20 K respectively, potentially induced by a combination of the interfacial effect of combined magnetic anionic and nonmagnetic cationic sublattices, as well as partial spin canting. The stability of the exchange bias behavior is confirmed by a training effect of less than 18 upon 10 hysteresis cycles. The semiconductivity of the material is determined, both experimentally and theoretically, with a bandgap energy of 1.68 eV. The findings render this material as a promising candidate for both, active electrode material in potassium ion batteries, and for spintronic application
