[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Conductometric semiconducting metal oxide gas sensors have been widely used and investigated in the detection of gases. Investigations have indicated that the gas sensing process is strongly related to surface reactions, so one of the important parameters of gas sensors, the sensitivity of the metal oxide based materials, will change with the factors influencing the surface reactions, such as chemical components, surface-modification and microstructures of sensing layers, temperature and humidity. In this brief review, attention will be focused on changes of sensitivity of conductometric semiconducting metal oxide gas sensors due to the five factors mentioned above.

Metal oxide gas sensors: Sensitivity and influencing factors

Transparent conductors as solar energy materials: A panoramic review

Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties Lots of metal oxide nanostructures have been developed to improve the gas sensing properties such as sensitivity, selectivity, response speed, and so on Here, we provide a brief overview of metal oxide nanostructures and their gas sensing properties from the aspects of particle size, morphology and doping When the particle size of metal oxide is close to or less than double thickness of the space-charge layer, the sensitivity of the sensor will increase remarkably, which would be called "small size effect", yet small size of metal oxide nanoparticles will be compactly sintered together during the film coating process which is disadvantage for gas diffusion in them In view of those reasons, nanostructures with many kinds of shapes such as porous nanotubes, porous nanospheres and so on have been investigated, that not only possessed large surface area and relatively mass reactive sites, but also formed relatively loose film structures which is an advantage for gas diffusion Besides, doping is also an effective method to decrease particle size and improve gas sensing properties Therefore, the gas sensing properties of metal oxide nanostructures assembled by nanoparticles are reviewed in this article The effect of doping is also summarized and finally the perspectives of metal oxide gas sensor are given

/pdf/metal-oxide-nanostructures-and-their-gas-sensing-properties-5exdmrct20.pdf

Metal Oxide Nanostructures and Their Gas Sensing Properties: A Review

Aligned Single‐Crystalline Si Nanowire Arrays for Photovoltaic Applications

The main drawbacks of modern solar-cell technologies are low-quality surface passivation, recombination losses, and carrier selectivity, which limit their efficiency. Therefore, this study proposes an innovative universal approach for a double-barrier two-dimensional (2D) quantum well (QW) passivation structure for solar cells. To this end, c-Si solar cells were examined as model cells. Preliminary investigations (e.g., contact resistance, passivation, and recombination current density) were conducted with a stack of SiOx/nc-Si/SiOx QW on n-type surfaces, and excellent results were obtained with a 30 nm-thick nc-SiOx(n) carrier-selective layer. Furthermore, the effects of different QW thicknesses and doping doses on the surface passivation of such contacts were studied, and the best results were achieved for a 5 nm QW. These QWs also exhibited a low degree of dopant diffusion, which was suppressed by the double SiOx layer. Furthermore, the 2D QW passivation structure with carrier-selective layers, which was denoted as a heterojunction with quantum well (HQW) solar cell, exhibited an excellent passivation improvement and had a lifetime (τeff) of 2746 μs and an implied open-circuit voltage (iVoc) of 736 mV for a 5 nm 2D QW structure. Moreover, a fabricated 5 nm 2D QW-based silicon heterojunction (SHJ) solar cell exhibited an open-circuit voltage (Voc) of 732.5 mV, a short-circuit current density (Jsc) of 39.5 mA/cm2, a fill factor (FF) of 77.95%, and an efficiency (Eff) of 22.55%. To validate these findings, theoretical calculations were performed using the experimental results, which confirmed the resonance tunneling of charge carriers across the 5 nm HWQ structure. 

Double-Barrier Quantum-Well Structure: An Innovative Universal Approach for Passivation Contact for Heterojunction Solar Cells

Ferroelectricity Based Memory Devices: New-Generation of Materials and Applications

A bilayered cathode interfacial structure consisting of lithium fluoride (LiF) and pyromellitic dianhydride (PMDA) was used between Al and tris-(8-hydroxyquinoline) aluminum (Alq 3 ) in the organic light-emitting diode (OLED), and a better performance enhancement compared to the OLED with a single LiF interfacial layer was achieved by using an optimal thickness combination of the bilayered interfacial structure (0.3 nm LiF/0.7 nm PMDA). The bilayered interfacial stucture with an optimum thickness combination decreased the parallel bulk resistance and lowered the electron injection barrier height between Al and Alq 3 according to the impedance and in situ ultraviolet photoelectron spectroscopy measurements, respectively.

Performance Improvement of the Organic Light-Emitting Diodes by Using a LiF/Pyromellitic Dianhydride Stacked Cathode Interfacial Layer

In this work, CdTe films were prepared by r.f. magnetron sputtering. Influence of conventional wet and dry CdCl 2 treatments on the structural and optical properties of CdTe films were investigated by field emission scanning electron microscope (FE-SEM), x-ray diffraction (XRD), and UV-Visible spectrophotometer. Also, CdS/CdTe thin film solar cells were fabricated by all sputtering process and the cell characteristics were studied. The as-deposited CdTe thin films had a zincblende structure highly oriented with the (111) direction parallel to the substrate surface. The CdTe films lose their preferred orientation and become polycrystalline by heat treatment with dry CdCl 2 treatment. The wet CdCl 2 treatment exhibited a similar trend, but is less effective for grain growth than dry CdCl 2 treatment. The photovoltaic properties of the CdS/CdTe solar cell were considerably improved with the increase in the annealing temperature, which was caused by the increase of grain size in CdTe films. However, the wet CdCl 2 process was not suitable for reproducible fabrication.

Comparative study of CdTe thin film solar cells with wet and dry CdCl 2 treatment process

http://ocean.kisti.re.kr/downfile/crosscheck/kieeme/JAKO201634864483639.pdf

Junsin Yi

Papers

Double-Barrier Quantum-Well Structure: An Innovative Universal Approach for Passivation Contact for Heterojunction Solar Cells

Ferroelectricity Based Memory Devices: New-Generation of Materials and Applications

Performance Improvement of the Organic Light-Emitting Diodes by Using a LiF/Pyromellitic Dianhydride Stacked Cathode Interfacial Layer

Comparative study of CdTe thin film solar cells with wet and dry CdCl 2 treatment process

Present Status of Thin Film Solar Cells Using Textured Surfaces: A Brief Review