In Situ Recrystallization of Co-Evaporated Cu(In,Ga)Se2 Thin Films by Copper Chloride Vapor Treatment towards Solar Cell Applications

Cu(In,Ga)Se2 (or CIGS) thin films and devices were fabricated using a modified three-stage process. Using high deposition rates and a low temperature during the process, a copper chloride vapor treatment was introduced in between the second and third stages to enhance the films properties. X-ray diffraction and scanning electron microscopy demonstrate that drastic changes occur after this recrystallization process, yielding films with much larger grains. Secondary ion mass spectrometry shows that the depth profile of many elements is not modified (such as Cu, In and Se) while others change dramatically (such as Ga and Na). Because of the competing effects of these changes, not all parameters of the solar cells are enhanced, yielding an increase of 15% in the device efficiency at the most.

DEVELOPMENT OF EFFECTIVE CATALYSTS FOR PROCESSING C3-C4 HYDROCARBONS

The aim of the article is to study the effect of preparation and activation methods of a modified zeolite-containing catalyst on the activity and stability of catalytic properties displayed by it during the conversion of C3-C4 hydrocarbons. During the experiment, the industrial cracking catalyst OMNIKAT, which is a zeolite in the sodium form, was used as the initial one. Zinc, gallium, and REE (rare earth elements) were sequentially applied to decationized samples of this catalyst by ion exchange, impregnation, and dry mechanical mixing, and the effect of these methods on the catalytic properties of the zeolite-containing catalyst was observed. As a result of a comparative analysis of the regularities of aromatization of C3-C4 hydrocarbons, it was found that the mechanical mixing method is the most preferable, since it provides the best process performance. In order to improve the activity and stability of the catalysts, thermocouple and thermal activations were carried out during the preparation process. Further, differences were revealed for the thermocouple and thermal activation of the modified catalyst and their effect on the activity and selectivity of the zinc-galliumzeolite-containing catalyst with respect to ArH (aromatic hydrocarbons) in the process of conversion of C3-C4 hydrocarbons. The choice of these particular operations was dictated by the fact that preliminary thermal and thermal vapor treatment of the catalyst practically does not require significant capital expenditures, i.e., economically most acceptable. Regularities of reaction-regeneration cycles were established. Thus, the optimal technological parameters for the regeneration of catalytic compositions are: temperature - 600°C, atmospheric pressure, oxidizer - air feed rate - 2 h-1, which lead to the restoration of the activity and selectivity of the spent catalyst to the fresh level. Studies of the of oxidative regeneration process a zinc-gallium-zeolite-containing catalyst have shown that while maintaining a clearly regulated regeneration regime, the activity of the latter is restored. The main task of the research was the development of effective catalysts for the conversion of C3- C4 hydrocarbons. Therefore, in the first place, we compared the conversion rates and selectivity for ArH. The proposed catalyst is characterized by good operational properties (high activity and long service life), providing 59.2% by weight of the target product yield at 98.8% conversion of C3-C4 hydrocarbons.

Diamine vapor treatment of viscoelastic graphene oxide liquid crystal for gas barrier coating

A layered graphene oxide/ethylenediamine (GO/EDA) composite film was developed by exposing aqueous GO liquid crystal (GOLC) coating to EDA vapor and its effects on the gas barrier performance of GO film were systematically investigated. When a GO/EDA coating with a thickness of approximately 1 μm was applied to a neat polyethylene terephthalate (PET) film, the resultant film was highly impermeable to gas molecules, particularly reducing the gas permeance up to 99.6% for He and 98.5% for H2 in comparison to the neat PET film. The gas barrier properties can be attributed to the long diffusion length through stacked GO nanosheets. The EDA can crosslink oxygen-containing groups of GO, enhancing the mechanical properties of the GO/EDA coating with hardness and elastic modulus values up to 1.14 and 28.7 GPa, respectively. By the synergistic effect of the viscoelastic properties of GOLC and the volatility of EDA, this coating method can be applied to complex geometries and EDA intercalation can be spontaneously achieved through the scaffold of the GOLC.

Switchable Multimode Microlaser based on AIE Microsphere

<p><a>Switchable multimode microlasers are of great significance to the development of photonic devices with high integration levels.</a> <a>Herein, we demonstrate an acid/alkaline gas responsive multimode AIEgen@starch microsphere-based microlaser. The aggregation-induced emission (AIE) active fluorescent dye ASCPI is used as the gain medium in this study. ASCPI was weakly emissive in water but became highly emissive when introduced to the starch microsphere as a guest molecule. The resultant ASCPI@starch microsphere worked well as a typical whispering-gallery-mode microlaser. The laser mode wavelengths were size dependent. Due to the sensitivity of ASCPI to pH, the output wavelength of the microlaser could be switched to shorter wavelength by acetic acid vapor treatment or longer wavelength by NH₃ vapor treatment. This work will provide a useful enlightenment for the rational design of effective switchable lasers using AIE materials with a simple preparation procedure.</a></p>

Switchable Multimode Microlaser based on AIE Microsphere

<p><a>Switchable multimode microlasers are of great significance to the development of photonic devices with high integration levels.</a> <a>Herein, we demonstrate an acid/alkaline gas responsive multimode AIEgen@starch microsphere-based microlaser. The aggregation-induced emission (AIE) active fluorescent dye ASCPI is used as the gain medium in this study. ASCPI was weakly emissive in water but became highly emissive when introduced to the starch microsphere as a guest molecule. The resultant ASCPI@starch microsphere worked well as a typical whispering-gallery-mode microlaser. The laser mode wavelengths were size dependent. Due to the sensitivity of ASCPI to pH, the output wavelength of the microlaser could be switched to shorter wavelength by acetic acid vapor treatment or longer wavelength by NH₃ vapor treatment. This work will provide a useful enlightenment for the rational design of effective switchable lasers using AIE materials with a simple preparation procedure.</a></p>

Recovery of free volume in PIM-1 membranes through alcohol vapor treatment

Physical aging is currently a major obstacle for the commercialization of PIM-1 membranes for gas separation applications. A well-known approach to reversing physical aging effects of PIM-1 membranes at laboratory scale is soaking them in lower alcohols, such as methanol and ethanol. However, this procedure does not seem applicable at industrial level, and other strategies must be investigated. In this work, a regeneration method with alcohol vapors (ethanol or methanol) was developed to recover permeability of aged PIM-1 membranes, in comparison with the conventional soaking-in-liquid approach. The gas permeability and separation performance, before and post the regeneration methods, were assessed using a binary mixture of CO2 and CH4 (1:1, v:v). Our results show that an 8-hour methanol vapor treatment was sufficient to recover the original gas permeability, reaching a CO2 permeability > 7000 barrer.