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The catalytic active sites of NiFe and NiFeCr (oxy)hydroxides are revealed byoperandospectroscopic techonologies for alkaline water oxidation.

A spin-coating-free fabrication sequence has been developed for the fabrication of highly efficient organic-inorganic halide perovskite solar cells (PSCs). A novel blow-drying method is demonstrated to be successful in depositing high quality mesoporous TiO2 (mp-TiO2), methylammonium lead halide (CH3NH3PbI3) perovskite and spiro-MeOTAD layers. When combined with compact TiO2 (c-TiO2) deposited by spray pyrolysis which is also a spin-coating-free process, a stabilized power conversion efficiency exceeding 17% can be achieved for the glass/FTO/c-TiO2/mp-TiO2/ CH3NH3PbI3/spiro-MeOTAD/Au device. This is the highest efficiency for PSCs fabricated without the use of spin-coating to our knowledge. This method provides a pathway towards a scalable process for fabricating high-performance, large area and reproducible PSCs.

Abstract Herein, we report the dual functionality of a single n-type gallium nitride (n-GaN) layer as an electron transporter and transparent conductor, which has applications in reusable organic solar cells. After silicon doping with an optimized electron concentration, thin-film layer of GaN showed exceptional electrical properties including charge carrier mobility of 161 cm2 V−1s−1, electrical conductivity of 1.4ⅹ106 S cm−1, and sheet resistance of 11.1 Ω cm−2. Organic solar cells based on n-GaN exhibited power conversion efficiency comparable to those based on a conventional ITO/ZnO bilayered cathode. Furthermore, the n-GaN substrates exhibited reusability; due to excellent chemical stability of n-GaN, the reconstructed organic solar cells maintained their initial performance after the substrates were recycled. We suggest a new type of reusable n-GaN cathode layer featuring an integrated electron transporting layer and transparent electrode.

AbstractExamination of results from the pilot production of buried‐contact solar cells (BCSC) allows several new insights into the effects of the substrate resistivity, the differences between upright and inverted pyramid texturing, the reflection after encapsulation and the doping level at which the emitter begins to dominate the overall recombination. A lower substrate resistivity in conjunction with thicker wafers reduces the effects of a high back surface recombination velocity and allows both higher voltages and efficiencies. In BCSCs with low substrate resistivities, the voltage is not limited by the back but by the emitter diffusion and the dislocation formation at the surface. Contrary to previous reports, best results have been realized with upright pyramids rather than inverted pyramids. In addition, the relative performance of the upright pyramids improves after encapsulation owing to the less than optimal unencapsulated reflection of these surfaces in the regions of the pyramid peaks where oxide layers are too thin to gain benefits as an antireflection layer. Recent results also indicate that the contributions to the dark saturation current from both the heavily phosphorus‐diffused region beneath the metal contact and the more lightly diffused top surface emitter are less than indicated previously. Finally, comparison between experimentally obtained voltages and those predicted through modelling with PC‐1D provides an estimate of the bulk material lifetimes in the pilot line cells.

The lifetime of high energy phonons in a QD superlattice is computed for plausible model materials from Time Dependent Perturbation Theory (TDPT). Klemens decay can be inhibited for a range of high energy phonons if a significant phonon bandgap exists. Ridley-type decays can compete with Klemens for speed due to the large density of states available for decay products on some decay paths and are typically a few picoseconds. In diamond superlattices where QDs occupy the majority of the unit cell, computed lifetimes can be as long as hundreds of picoseconds for certain symmetry directions.

Abstract Efficient hydrogen production from water by photocatalysis under sunlight requires a significant improvement in light-harvesting capability. Zinc sulfide is a promising, inexpensive hydrogen generation photocatalyst, but in its pure, bulk form it is only active under ultra-violet light. Here, we show clear evidence of photoelectrochemical activity of ZnS thin films under visible-light irradiation without any co-catalysts, achieved through defect engineering. Fabrication of nanostructured ZnS under controlled conditions introduces defects, and hence intermediate electronic states within the band gap, which allow significant absorption of light at energies below the band gap energy of pure, bulk ZnS. The measured band gap of the ZnS thin films is ~2.4 eV, while the photocurrent density exceeds 1.5 mA/cm2 under visible-light irradiation (λ≥435 nm). This is the first measurement of such high photocurrents for undoped ZnS under visible light.

At local scales, habitat availability influences interactions between native and invasive species. Habitat availability may also predict patterns in native communities and invasive species at biogeographic scales when both native and invasive species have specific habitat requirements. The New Zealand porcelain crab, Petrolisthes elongatus, has invaded intertidal rocky shores around Tasmania, Australia, where it is found in high densities (>1800 m(2)) under rocks. A hierarchical sampling approach was used to investigate 1) the relationship between habitat availability (rock cover) and the biomass and abundance of P. elongatus, and 2) the relationship between P. elongatus biomass and native communities at local and regional scales. Invertebrate communities and habitat availability were sampled at multiple sites in the north and south regions of Tasmania. P. elongatus biomass and abundance were positively correlated with rock cover and patterns were consistent at the biogeographic scale (between regions). P. elongatus biomass was positively correlated with native species richness, biomass and abundance highlighting their co-dependence on rock cover. However, multivariate analyses indicated a different native community structure with increasing P. elongatus biomass. Flat, strongly adhering gastropods (chitons and limpets) were positively correlated with P. elongatus biomass, whereas mobile gastropods and crabs were negatively correlated with P. elongatus biomass. Despite local scale variation, there were clear consistent relationships between habitat-availability and the biomass of P. elongatus, and between native communities and the biomass of P. elongatus suggesting that the relationships between native and invasive species may be predictable at large spatial scales. Moreover, the strong relationships between P. elongatus biomass and changes in native community structure suggest a greater understanding of its impact is needed so that appropriate management plans can be developed.

Abstract This paper demonstrates that a double-layer antireflection (DLAR) coating can be fabricated using a single material, titanium dioxide (TiO2). The optical properties of the top and bottom TiO2 layers were controlled by varying the deposition and sintering conditions, resulting in a range of refractive indices, n=1.73–2.63 at 600 nm . Weighted average reflectances of 6.5% (measured) and 7.0% (calculated) were achieved for TiO2 DLAR coatings in air and under glass, respectively. When implemented in a high-efficiency silicon solar cell, a short-circuit current density increase of Δ J sc =2.5 mA/cm 2 can be expected for an optimised TiO2 DLAR coating when compared to a commercial TiO2 single-layer antireflection coating.