Quantitative luminescence mapping of Cu(In,Ga)Se2 thin‐film solar cells

We investigate photoluminescence and electroluminescence (PL and EL) emission images from Cu(In,Ga)Se₂‐based solar cells by means of a Hyperspectral Imager. Using the generalized Planck's law, maps of the effective quasi‐Fermi level splitting Δμ_eff in absolute values are obtained. A good agreement is found between the spatially averaged splitting in PL and the global open‐circuit voltage. However, from a local carrier transport discussion, we conclude that the equality does not hold locally. The spatial variations are rather attributed to local depth variations of the quasi‐Fermi level splitting due to material properties spatial fluctuations. By comparing PL and EL emissions, we discuss qualitatively the local effective lifetimes and collection efficiencies. Copyright © 2014 John Wiley & Sons, Ltd.     

Aluminum‐enhanced alkali diffusion from float glass to PVD‐sputtered silica thin films

Interdiffusion processes between aluminum enriched PVD‐sputtered silica thin films and industrial float soda‐lime silicate glass substrates are quantitatively studied using SIMS analysis. Heat treatments are performed at temperatures close or above the glass transition temperature of the float glass. Aluminum doping of the film is shown to strongly increase the migration of alkali from the glass substrate to the silica thin film. In particular the final alkali content in the film exhibits a linear scaling with the aluminum concentration. An interdiffusion process is evidenced between bulk alkali ions and protons originating from a significant water content in the as‐deposited silica film. Experimental measurements of sodium concentration are shown to be consistent with a simple thermodynamic model based on the equilibration of the activity of sodium between the film and the glass substrate.     

Specific cationic photoinitiators for near UV and visible LEDs: Iodonium versus ferrocenium structures

Two iodonium salts based on a coumarin chromophore are investigated for polymerization upon light emitting diode irradiations (LEDs). They work as one‐component photoinitiators. They initiate the cationic polymerization of epoxides (under air) and vinylethers (laminate) upon exposure to violet LEDs (385 and 405 nm). Excellent polymerization profiles are recorded. Their efficiency is quite similar to that of a ferrocenium salt. Interpenetrating polymer networks can also be obtained through a concomitant cationic/radical photopolymerization of an epoxy/acrylate blend monomer. The light absorption properties of these new salts as well as the involved photochemical mechanisms are investigated for the first time through electron spin resonance, laser flash photolysis, steady state photolysis experiments. Molecular orbital calculations are also used to shed some light on the initiation mechanisms. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42759.     

Non‐Covalent Functionalization of Graphene Using Self‐Assembly of Alkane‐Amines

A simple, versatile method for non‐covalent functionalization of graphene based on solution‐phase assembly of alkane‐amine layers is presented. Second‐order Møller–Plesset (MP2) perturbation theory on a cluster model (methylamine on pyrene) yields a binding energy of ≈220 meV for the amine–graphene interaction, which is strong enough to enable formation of a stable aminodecane layer at room temperature. Atomistic molecular dynamics simulations on an assembly of 1‐aminodecane molecules indicate that a self‐assembled monolayer can form, with the alkane chains oriented perpendicular to the graphene basal plane. The calculated monolayer height (≈1.7 nm) is in good agreement with atomic force microscopy data acquired for graphene functionalized with 1‐aminodecane, which yield a continuous layer with mean thickness ≈1.7 nm, albeit with some island defects. Raman data also confirm that self‐assembly of alkane‐amines is a non‐covalent process, i.e., it does not perturb the sp² hybridization of the graphene. Passivation and adsorbate n‐doping of graphene field‐effect devices using 1‐aminodecane, as well as high‐density binding of plasmonic metal nanoparticles and seeded atomic layer deposition of inorganic dielectrics using 1,10‐diaminodecane are also reported.     

Preparation of Phospholipid Multilayer Patterns of Controlled Size and Thickness by Capillary Assembly on a Microstructured Substrate

By dragging a phospholipid solution on microstructured silicon surfaces, phospholipid molecules are selectively deposited inside the microstructures to get regular phospholipid multilayer patterns of controlled thickness over a large scale (～cm²). By varying the dragging speed, the thickness of the patterns varies between 28 and 100 nm on average (7 to 25 bilayers). Electroswelling of phospholipid multilayer patterns leads to the formation of giant liposomes of controlled size and narrow size distributions.     

Nucleate Boiling on a Single Site: Contact Angle Analysis for a Quasi-2D Growing Vapour Bubble

Heat transfer prediction under boiling condition is still unresolved. In this paper, a basic study on bubble growth is carried out. Recent works show that contact line region plays an important role for heat and mass transfer in nucleate boiling regime. Three dimension experimental set-up lead to a mirage effect which disturbs measurements. To overcome this problem, a new quasi two dimensional experimental set-up is designed. This Hele–Shaw like configuration allows measuring the contact angle and contact line displacement during the bubble growth. A noticeable behavior of the contact angle is observed, and the influence of the sub-cooling level on the bubble growth rate and the contact angle value is studied.     

A multi-agent system for energy management of distributed power sources

The field of energy management is an area increasingly studied. However, most solutions are based on centralized systems and barely fulfil criterion like fault tolerance or adaptability. Also, these systems are often difficult to design because of the “top–down” approach used: the designer generally knows how each component has to respond separately, but a centralized management system focuses his attention solely on the overall reaction of the system. That is why a distributed management solution based on the paradigm of Multi-Agent Systems (MASs) is proposed in this paper. In addition to a more natural conception, based on a “bottom–up” approach, this solution ensures better system reliability. After reviewing the previous works, an application of MAS to power management in a hybrid power source is presented. Then, the system is tested using a simulation model. The results show that this approach is perfectly valid and can respond to most problems of centralized energy management systems (EMSs).     

Time-of-Flight camera based 3D point cloud reconstruction of a car

Modern car wash systems are generally controlled by light barriers and power measurement sensors. These sensors are directly mounted on the movable parts of the system which result in a slow regulation, leading to non-optimal performance, e.g. in terms of energy, water and detergent consumption or regarding the quality of the result.     

Modelling mechanical properties of spruce and Douglas fir timber by means of X-ray and grain angle measurements for strength grading purpose

This study proposes a model using data from a scanner (X-ray and grain angle measurements) to perform strength grading. The research also includes global measurements of modulus of elasticity (obtained by vibrations and ultrasound methods), static bending stiffness and bending strength of 805 boards of Douglas fir and 437 boards of spruce. This model can be used in an industrial context since it requires low computational time. The results of this study show that the developed model gives better results than the global non-destructive measurements of the elastic modulus commonly used in the industry. It also shows that this improvement is particularly higher in the case of Douglas fir than for spruce. The comparison has been made on both the quality of the mechanical properties assessment and on the improvement of the grading process according to the European standards by using different index.