Fluorographene/polyimide composite films: Mechanical,electrical, hydrophobic,thermal and low dielectric properties

Nowadays, dielectric materials with excellent mechanical and hydrophobic properties are desired for use in the integrated circuits (ICs). For this reason, low dielectric constant fluorographene/polyimide (FG/PI) composite films were prepared by a facile solution blending method, suggesting that the mechanical, electrical, hydrophobic and thermal properties were significantly enhanced in the presence of FG. With addition of 1 wt% FG, the tensile strength, Young’s modulus and elongation at break were dramatically increased by 139%, 33% and 18% respectively when compared with pure PI film. Furthermore, composite films exhibit superior hydrophobic and thermal stability performance. Especially, the FG/PI film with 0.5 wt% of FG possessing a low dielectric constant of 2.48 and a good electrical insulativity that is lower than 10⁻¹⁴ S m⁻¹. Therefore, by their excellent performance, FG/PI hybrid films represent suitable candidate solutions with applications in the microelectronics and aerospace industries.     

A perspective on the recent progress in solution-processed methods for highly efficient perovskite solar cells

Perovskite solar cells (PSCs) were developed in 2009 and have led to a number of significant improvements in clean energy technology. The power conversion efficiency (PCE) of PSCs has increased exponentially and currently stands at 22%. PSCs are transforming photovoltaic (PV) technology, outpacing many established PV technologies through their versatility and roll-to-roll manufacturing compatibility. The viability of low-temperature and solution-processed manufacturing has further improved their viability. This article provides a brief overview of the stoichiometry of perovskite materials, the engineering behind various modes of manufacturing by solution processing methods, and recommendations for future research to achieve large-scale manufacturing of high efficiency PSCs.     

Foreign Particle Promoted Crystalline Nucleation for Growing High‐Quality Ultrathin Rubrene Films

Introducing foreign particles or agents as nucleator is an efficient way to promote crystallization in the crystal growth field, with the advantage to speed up the crystallizing rate and control the growth process. However, in the field of organic crystalline film growth, where the crystallization and morphology modulation are of significant importance in optoelectronics, this method has rarely been utilized. Particularly, some potential high‐performance materials such as rubrene face the problem of crystallization during film formation. Here a strategy is reported to promote the crystallization of rubrene films in the initial stage assisted by foreign particles. Highly ordered thin film from the sub‐monolayer stage can be achieved. Efficient charge transport and high mobility up to 2.95 cm² V^?1 s^?1 are achieved on thus ultrathin crystalline films. Such a method enables the well controlling of the film growth from the very early stage and produces uniform crystalline films with good reproducibility, thus highly promising to yield desired optoelectrical properties and applications.     

Binder‐Free and Carbon‐Free 3D Porous Air Electrode for Li‐O2 Batteries with High Efficiency,High Capacity,and Long Life

Pt‐Gd alloy polycrystalline thin film is deposited on 3D nickel foam by pulsed laser deposition method serving as a whole binder/carbon‐free air electrode, showing great catalytic activity enhancement as an efficient bifunctional catalyst for the oxygen reduction and evolution reactions in lithium oxygen batteries. The porous structure can facilitate rapid O₂ and electrolyte diffusion, as well as forming a continuous conductive network throughout the whole energy conversion process. It shows a favorable cycle performance in the full discharge/charge model, owing to the high catalytic activity of the Pt‐Gd alloy composite and 3D porous nickel foam structure. Specially, excellent cycling performance under capacity limited mode is also demonstrated, in which the terminal discharge voltage is higher than 2.5 V and the terminal charge voltage is lower than 3.7 V after 100 cycles at a current density of 0.1 mA cm^?2. Therefore, this electrocatalyst is a promising bifunctional electrocatalyst for lithium oxygen batteries and this depositing high‐efficient electrocatalyst on porous substrate with polycrystalline thin film by pulsed laser deposition is also a promising technique in the future lithium oxygen batteries research.     

The effect of thermal annealing on the adherence of Al2O3 films deposited by LP-MOCVD on several high alloy steels

Thin alumina films, deposited at 280°C on several high alloy steels by low-pressure metal-organic chemical vapor deposition (LP-MOCVD), were annealed at 0.17 kPa in a nitrogen atmosphere for 2, 4, and 17 h at 600 and 800°C. Film adhesion was studied by scanning scratch testing (SST) and Auger electron spectroscopy (AES). The best adhesion properties were obtained with commercial oxide dispersion-strengthened (ODS) high-temperature alloys, especially PM 3030. Among the 'normally' high alloy stainless steels, type AISI-321 showed the best adhesion. The other stainless steel-alumina combinations exhibited a reduced critical load, L_c, after thermal treatment. Alumina on ODS alloys exhibited an increased adhesion. AES studies revealed that this increase could be explained by: (1) the presence of sulfur-trapping elements, preventing segregation of sulfur at the interface; and (2) titanium and carbon enrichment at the interface, resulting in an anchoring effect between the oxide and the substrate.     

The influence of binder content on the water transport properties of waterborne acrylic paints

Diffusion coefficients and sorption isotherms of water in waterborne acrylic paint films and in the pure binder of the paints have been measured by gravimetric sorption. Solubility of water was found to enhance with the increased binder content in the paint films while the diffusivity of water decreased significantly. Sorption isotherms in the paint and pure copolymer films were correlated with the Flory Huggins theory and ENSIC model, respectively. Fickian diffusion was observed in both types of films and the kinetic data were best correlated with a numerical model which takes into account the concentration dependency of the diffusion coefficient and the dimensional change of the film due to sorption. It was concluded that the utilization of a simplified analytical solution may lead to significant errors in the estimation of diffusivities.     

The kinetic behaviour of ion injection in WO3 based films produced by sputter and sol–gel deposition: Part II. Diffusion coefficients

The use of AC impedance spectroscopy for kinetic study of the ion intercalation into WO₃ films is reviewed, and methods for extracting the diffusion coefficient of the ion diffusion process from AC impedance spectroscopy data are described. These are applied to several different electrochromic thin films, all based on tungsten oxide, and the electrochromic performance is correlated with the diffusion coefficient. The results are also compared with results of a previous paper which concentrated on modelling the voltage response of films coloured and bleached using constant current charge injection techniques. Several examples of non-ideal behaviour of the impedance spectra are observed, including depressed semicircles and evidence of two semicircles. A full discussion of these effects is given in a following paper.