Fabrication of Patterned Inorganic–Organic Hybrid Film for the Optical Waveguide by Microfluidic Lithography

Inorganic–organic hybrid materials for the optical waveguide were synthesized by the sol–gel process starting from the acid-catalyzed solutions of phenyltrimethoxysilane, methyltriethoxysilane, and tetraethylorthosilicate. The control of the refractive index in the organically modified silicate films was achieved by varying the content of phenyltrimethoxysilane incorporated as a refractive index modifier. A single spin-coating with the precursor solution produced a crack-free buffer layer of 22-μm thickness with a dense microstructure. For the fabrication of the patterned guiding layer on top of the buffer layer, the microfluidic lithography method was used. The patterned microlines of the linewidth of 20–35 μm with a sharp edge definition could form by filling the precursor solutions into the microchannels associated with the polydimethylsiloxane microfluidic device. The patterned guiding layer was optically transparent as similar as the bare quartz glass at the wavelength above 500 nm and had a low propagation loss of 0.77 dB/cm at 1310 nm.     

Application of amine-tethered solid sorbents for direct CO2 capture from the ambient air

While current carbon capture and sequestration (CCS) technologies for large point sources can help address the impact of CO(2) buildup on global climate change, these technologies can at best slow the rate of increase of the atmospheric CO(2) concentration. In contrast, the direct CO(2) capture from ambient air offers the potential to be a truly carbon negative technology. We propose here that amine-based solid adsorbents have significant promise as key components of a hypothetical air capture process. Specifically, the CO(2) capture characteristics of hyperbranched aminosilica (HAS) materials are evaluated here using CO(2) mixtures that simulate ambient atmospheric concentrations (400 ppm CO(2) = "air capture") as well as more traditional conditions simulating flue gas (10% CO(2)). The air capture experiments demonstrate that the adsorption capacity of HAS adsorbents are only marginally influenced even with a significant dilution of the CO(2) concentration by a factor of 250, while capturing CO(2) reversibly without significant degradation of performance in multicyclic operation. These results suggest that solid amine-based air capture processes have the potential to be an effective approach to extracting CO(2) from the ambient air.     

All‐Solution‐Processed Indium‐Free Transparent Composite Electrodes based on Ag Nanowire and Metal Oxide for Thin‐Film Solar Cells

Fully solution‐processed Al‐doped ZnO/silver nanowire (AgNW)/Al‐doped ZnO/ZnO multi‐stacked composite electrodes are introduced as a transparent, conductive window layer for thin‐film solar cells. Unlike conventional sol–gel synthetic pathways, a newly developed combustion reaction‐based sol–gel chemical approach allows dense and uniform composite electrodes at temperatures as low as 200 °C. The resulting composite layer exhibits high transmittance (93.4% at 550 nm) and low sheet resistance (11.3 Ω sq^‐1), which are far superior to those of other solution‐processed transparent electrodes and are comparable to their sputtered counterparts. Conductive atomic force microscopy reveals that the multi‐stacked metal‐oxide layers embedded with the AgNWs enhance the photocarrier collection efficiency by broadening the lateral conduction range. This as‐developed composite electrode is successfully applied in Cu(In_1‐x,Ga_x)S₂ (CIGS) thin‐film solar cells and exhibits a power conversion efficiency of 11.03%. The fully solution‐processed indium‐free composite films demonstrate not only good performance as transparent electrodes but also the potential for applications in various optoelectronic and photovoltaic devices as a cost‐effective and sustainable alternative electrode.     

Design and fabrication of a significantly shortened multimode interference coupler for polarization splitter application

We report that we have successfully designed and fabricated a significantly shortened multimode interference coupler for application in polarization splitter, using a phenomenon that we termed "quasi-state" (QS) imaging effect. First, we identified and analyzed the QS imaging effect, and, based on the QS analysis, designed and fabricated a novel multimode interference (MMI) device with its split length shortened to 1/5 of a normally designed MMI split length. The fabrication is simple and cost effective and the fabricated device shows outstanding characteristics in extinction ratio, signal homogeneity, excess loss, and tolerance in the length of the splitter.     

Synthesis of silver nanoparticles using the polyol process and the influence of precursor injection

Spherical silver nanoparticles with various sizes and standard deviations were synthesized by the polyol process. Two different synthesis methods were compared in order to investigate the influence of reaction parameters on the resulting particle size and its distribution. In the precursor heating method, wherein a solution containing silver nitrate was heated to the reaction temperature, the ramping rate was determined to be a critical parameter affecting the particle size. In contrast, in the precursor injection method, in which a silver nitrate aqueous solution was injected into hot ethylene glycol, because of rapid nucleation, the injection rate and the reaction temperature were important factors in terms of reducing the particle size and attaining monodispersity. Silver nanoparticles with a size of 17 ± 2?nm were obtained at an injection rate of 2.5?ml?s(-1) and a reaction temperature of 100?°C.     

Synthesis–Structure–Property Relationships for Hyperbranched Aminosilica CO2 Adsorbents

Hyperbranched aminosilica (HAS) adsorbents are prepared via the ring‐opening polymerization of aziridine in the presence of mesoporous silica SBA‐15 support. The aminopolymers are covalently bound to the silica support and capture CO₂ reversibly in a temperature swing process. Here, a range of HAS materials are prepared with different organic loadings. The effects of organic loading on the structural properties and CO₂ adsorption properties of the resultant hybrid materials are examined. The residual porosity in the HAS adsorbents after organic loading, as well as the molecular weights and degrees of branching for the separated aminopolymers, are determined to draw a relationship between adsorbent structure and performance. Humid adsorption working capacities and apparent adsorption kinetics are determined from experiments in a packed‐bed flow system monitored by mass spectrometry. Dry adsorption isotherms are presented for one HAS adsorbent with a high amine loading at 35 and 75 °C. These combined results establish the relationships between adsorbent synthesis, structure, and CO₂ adsorption properties of the family of HAS materials.     

Prediction of nonrandom mixing in lattice model with multi-references

A new lattice theory is proposed to describe nonrandom mixing behavior based on recently developed lattice model theory by Aranovich and Donohue. The present theory assumes multi-references in order to take into account interference effects on non-random mixing among pairs. The number of references was obtained from Monte Carlo simulations for monomer+hole mixtures. Monte Carlo simulation for hole [0]+monomer [1]+monomer [2] mixture shows that this theory is more accurate than Guggenheim’s quasi-chemical theory or the Aranovich-Donohue model in a wide range of temperatures and densities. Especially, even under the stringent condition of zero interaction energy parameter ε₁₂=0, the present theory predicts well the extent of nonrandom mixing. For dimer fluid the non-randomness is calculated using the surface fraction. Here three references was used as in the case of monomer fluid with chain connectivity constraints. Comparison of the theory with Monte Carlo simulation results for dimer+hole system shows a good agreement.