Bismuth vanadate (BiVO4) has been widely investigated as a photoanode material for photoelectrochemical (PEC) water splitting because it has a suitable bandgap and strong visible-light absorption. However, its performance is highly dependent on film thickness, as there is a trade-off between light absorption and charge transport. In this study, BiVO4 thin films with thicknesses of 200, 300, and 400 nm were deposited on FTO substrates via RF magnetron sputtering to systematically investigate the thickness-dependent PEC performance. X-ray diffraction and field-emission scanning electron microscopy confirmed the formation of uniform and crystalline BiVO4 thin films. UV–vis spectroscopy revealed that light absorption increased with film thickness. PEC measurements showed that the 300 nm BiVO4 photoanode delivered the highest photocurrent density of 1.91 mA cm-2 at 1.23 V vs. RHE, along with a maximum HC-STH efficiency of 0.309 %. Electrochemical impedance spectroscopy indicated that the 300 nm film exhibited the lowest charge transfer resistance, suggesting reduced charge recombination. Furthermore, the optimized photoanode maintained stable photocurrent for over 5 hours. These results highlight that precise thickness control via RF magnetron sputtering is critical for optimizing the PEC performance of BiVO4 photoanodes.

Solar energy has been recognized as an alternative energy source that can help address fuel depletion and climate change issues. As a renewable energy alternative to fossil fuels, it is an eco-friendly and unlimited energy source. Among solar cells, thin film Cu2ZnSn(S,Se)4 (CZTSSe) is currently being actively studied as an alternative to heavily commercialized Cu (In,Ga)Se2 (CIGS) thin film solar cells, which rely upon costly and scarce indium and gallium. Currently, the highest efficiency achieved by CZTSSe cells is 14.9 %, lower than the CIGS record of 23.35 %. When applied to devices, CZTSSe thin films perform poorly compared to other materials due to problems including lattice defects, conduction band offset, secondary phase information, and narrow stable phase regions, so improving their performance is essential. Research into ways of improving performance by doping with Germanium and Cadmium is underway. Specifically, Ge can be doped into CZTSSe, replacing Sn to reduce pinholes and bulk recombination. Additionally, partially replacing Zn with Cd can facilitate grain growth and suppress secondary phase formation. In this study, we analyzed the device’s performance after doping Ge into CZTSSe thin film using evaporation, and doping Cd using chemical bath deposition. The Ge doped thin film showed a larger bandgap than the undoped reference thin film, achieving the highest Voc of 494 mV in the device. The Cd doped thin film showed a smaller bandgap than the undoped reference thin film, with the highest Jsc of 36.9 mA/cm2. As a result, the thin film solar cells achieved a power conversion efficiency of 10.84 %, representing a 20 % improvement in power conversion efficiency compared to the undoped reference device.

Scanning probe microscopy (SPM) has become an indispensable tool in efforts to develop the next generation of nanoelectronic devices, given its achievable nanometer spatial resolution and highly versatile ability to measure a variety of properties. Recently a new scanning probe microscope was developed to overcome the tip degradation problem of the classic SPM. The main advantage of this new method, called Reverse tip sample (RTS) SPM, is that a single tip can be replaced by a chip containing hundreds to thousands of tips. Generally for use in RTS SPM, pyramid-shaped diamond tips are made by molding on a silicon substrate. Combining RTS SPM with Scanning spreading resistance microscopy (SSRM) using the diamond tip offers the potential to perform 3D profiling of semiconductor materials. However, damage frequently occurs to the completed tips because of the complex manufacturing process. In this work, we design, fabricate, and evaluate an RTS tip chip prototype to simplify the complex manufacturing process, prevent tip damage, and shorten manufacturing time.

The Cu2ZnSn(SxSe1-x)4 (CZTSSe) absorbers are promising thin film solar cells (TFSCs) materials, to replace existing Cu(In,Ga)Se2 (CIGS) and CdTe photovoltaic technology. However, the best reported efficiency for a CZTSSe device, of 13.6 %, is still too low for commercial use. Recently, partially replacing the Zn2+ element with a Cd2+element has attracting attention as one of the promising strategies for improving the photovoltaic characteristics of the CZTSSe TFSCs. Cd2+ elements are known to improve the grain size of the CZTSSe absorber thin films and improve optoelectronic properties by suppressing potential defects, causing short-circuit current (Jsc) loss. In this study, the structural, compositional, and morphological characteristics of CZTSSe and CZCTSSe thin films were investigated using X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), and Field-emission scanning electron microscopy (FE-SEM), respectively. The FE-SEM images revealed that the grain size improved with increasing Cd2+ alloying in the CZTSSe thin films. Moreover, there was a slight decrease in small grain distribution as well as voids near the CZTSSe/Mo interface after Cd2+ alloying. The solar cells prepared using the most promising CZTSSe absorber thin films with Cd2+ alloying (8 min. 30 sec.) exhibited a power conversion efficiency (PCE) of 9.33 %, Jsc of 34.0 mA/cm2, and fill factor (FF) of 62.7 %, respectively.

Cu2ZnSn(S,Se)4 (CZTSSe) based thin-film solar cells have attracted growing attention because of their earthabundant and non-toxic elements. However, because of their large open-circuit voltage (Voc)-deficit, CZTSSe solar cells exhibit poor device performance compared to well-established Cu(In,Ga)(S,Se)2 (CIGS) and CdTe based solar cells. One of the main causes of this large Voc-deficit is poor absorber properties for example, high band tailing properties, defects, secondary phases, carrier recombination, etc. In particular, the fabrication of absorbers using physical methods results in poor surface morphology, such as pin-holes and voids. To overcome this problem and form large and homogeneous CZTSSe grains, CZTSSe based absorber layers are prepared by a sputtering technique with different RTA conditions. The temperature is varied from 510 oC to 540 oC during the rapid thermal annealing (RTA) process. Further, CZTSSe thin films are examined with X-ray diffraction, X-ray fluorescence, Raman spectroscopy, IPCE, Energy dispersive spectroscopy and Scanning electron microscopy techniques. The present work shows that Cu-based secondary phase formation can be suppressed in the CZTSSe absorber layer at an optimum RTA condition.

Zinc oxide (ZnO) based transparent conducting oxides (TCO) thin films, are used in many applications such as solar cells, flat panel displays, and LEDs due to their wide bandgap nature and excellent electrical properties. In the present work, fluorine and aluminium-doped ZnO targets are prepared and thin films are deposited on soda-lime glass substrate using a RF magnetron sputtering unit. The aluminium concentration is fixed at 2 wt%, and the fluorine concentration is adjusted between 0 to 2.0 wt% with five different concentrations, namely, Al2ZnO98(AZO), F0.5AZO97.5(FAZO1), F1AZO97(FAZO2), F1.5AZO96.5(FAZO3), and F2AZO96(FAZO4). Thin films are deposited with an RF power of 40 W and working pressure of 5 m Torr at 270 oC. The morphological analysis performed for the thin film reveals that surface roughness decreases in FAZO1 and FAZO2 samples when doped with a small amount of fluorine. Further, optical and electrical properties measured for FAZO1 sample show average optical transmissions of over 89 % in the visible region and 82.5 % in the infrared region, followed by low resistivity and sheet resistance of 3.59 × 10−4 Ωcm and 5.52 Ω/sq, respectively. In future, these thin films with excellent optoelectronic properties can be used for thin-film solar cell and other optoelectronics applications.

Recent advances in technology using ultra-thin noble metal film in oxide/metal/oxide structures have attracted attention because this material is a promising alternative to meet the needs of transparent conduction electrodes (TCE). AZO/ Ag/AZO multilayer films are prepared by magnetron sputtering for Cu2ZnSn(S,Se)4 (CZTSSe) of kesterite solar cells. It is shown that the electrical and optical properties of the AZO/Ag/AZO multilayer films can be improved by the very low resistivity and surface plasmon effects due to the deposition of different thicknesses of Ag layer between oxide layers fixed at AZO 30 nm. The AZO/Ag/AZO multilayer films of Ag 15 nm show high mobility of 26.4 cm2/Vs and low resistivity and sheet resistance of 3.58*10−5 Ωcm and 5.0 Ω/sq. Also, the AZO/Ag (15 nm)/AZO multilayer film shows relatively high transmittance of more than 65% in the visible region. Through this, we fabricated CZTSSe thin film solar cells with 7.51% efficiency by improving the short-circuit current density and fill factor to 27.7 mV/cm2 and 62 %, respectively.

Cu2ZnSn(S,Se)4(CZTSSe) thin film solar cells areone of the most promising candidates for photovoltaic devices due to their earth-abundant composition, high absorption coefficient and appropriate band gap. The sputtering process is the main challenge to achieving high efficiency of CZTSSe solar cells for industrialization. In this study, we fabricated CZTSSe absorbers on Mo coated soda lime glass using different pressures during the annealing process. As an environmental strategy, the annealing process is performed with S and Se powder, without any toxic H2Se and/or H2S gases. Because CZTSSe thin films have a very narrow stable phase region, it is important to control the condition of the annealing process to achieve high efficiency of the solar cell. To identify the effect of process pressure during the sulfo-selenization, we experiment with varying initial pressure from 600 Torr to 800 Torr. We fabricate a CZTSSe thin film solar cell with 8.24 % efficiency, with 435 mV for open circuit voltage(VOC) and 36.98 mA/cm2 for short circuit current density(JSC), under a highest process pressure of 800 Torr.

담관의 게실은 Todani 분류에 부합하지 않는 드문 형태의 담관의 낭성 확장이며, 질환의 희소성으로 인하여 진료 현장에서 진단이나 치료에 어려움을 겪을 수 있다. 본 증례보고에서는 복통을 주소로 내원한 57세 여성 환자에서 발생한 간외 좌측 담관 게실의 증례를 문헌고찰과 함께 보고하고자 한다. 내원 당시 환자는 간기능 검사에서의 경미한 증가 외에 혈액검사상 이상 소견은 보이지 않았다. 전산화단층촬영과 자기공명 담도췌관조영술에서 간내담관의 합류 부분 근처에 슬러지 볼을 포함한 낭성 병변이 보였으나 병변의 기원은 명확히 보이지 않았다. 임상적으로는 Todani II형 총담관낭이 의심되었다. 환자의 복통이 지속되어 해당 병변에 대하여 수술적 절제를 시행하였고 수술 결과 좌측 담관 게실로 진단되었다. 절제된 조직은 병리학적 검사상 담도 상피로 덮인 게실로 확인되었다. 수술 후 합병증은 발생하지 않았으며 수술적 제거 후 환자의 증상은 호전되었다.

Cu2ZnSn(S,Se)4 (CZTSSe) films were prepared on Mo coated soda lime glass substrates by sulfo-selenization of sputtered stacked Zn-Sn-Cu(CZT) precursor films. The precursor was dried in a capped state with aqueous NaOH solution. The CZT precursor films were sulfo-selenized in the S + Se vapor atmosphere. Sodium was doped during the sulfo-selenization treatment. The effect of sodium doping on the structural and electrical properties of the CZTSSe thin films were studied using FE-SEM(field-emission scanning electron microscopy), XRD(X-ray diffraction), XRF(X-ray fluorescence spectroscopy), dark current, SIMS(secondary ion mass spectrometry), conversion efficiency. The XRD, XRF, FE-SEM, Dark current, SIMS and cell efficiency results indicated that the properties of sulfo-selenized CZTSSe thin films were strongly related to the sodium doping. Further detailed analysis and discussion for effect of sodium doping on the properties CZTSSe thin films will be discussed.

미리찌 증후군은 담낭결석증의 드문 합병증으로, 담낭 경부나 담낭관의 결석에 의한 압박으로 인해 총간관의 폐쇄가 발생하게 된다. 미리찌 증후군은 수술적 치료를 하게 되며 그 방법은 질환의 세부 분류에 따라 다양하다. 미리찌 증후군의 외과적 치료 후 발생한 담관 협착은 드문 합병증이며 담도-장 문합술을 시행한 환자에서 이를 내시경적으로 치료하는 것은 불가능하다. 본 증례는 미리찌 증후군의 수술적 치료 후 발생한 담관 문합부 협착을 장기간 경피경간 담도배액술로 치료하여 이를 문헌고찰과 함께 보고하는 바이다.

고압균질화 기반 nanosuspension화은 난용 혹은 불용인 기능성 물질의 가용성을 높이는 기술로서 식품산업체로부터 관심을 받고 있다. 그러나 nanosuspension은 나노 크기로 분산된 난용성 입자들은 응집 또는 Ostwald ripening 현상에 쉽게 노출되기 때문에, 저장안정성이 낮다. 그러므로 이러한 nanosuspension에 유화제 및 고분자 물질 등의 분산안정제를 도입함으로써 위의 현상을 지연시키거나 방지하기 위해 반드시 필요하다. 이 연구는 분산안정제의 특성이 nanosuspension화된 분지쇄아미노산의 용해도 및 저장안정성에 미치는 영향을 평가했다. Tween 80, Span 80 또는 lysolecithin을 10 mM 인산 완충 용액(pH 7)에 녹이고, pH를 3 또는 6으로 보정하여 안정제 용액을 제조하였다. 분지쇄아미노산 혼합물(L-leucine:L-isoleucine:L-valine=2:1:1)을 최종 농도가 5%(w/v)가 되도록 안정제 용액에 첨가 하였다. 모든 분지쇄아미노산 현탁액을 25°C에서 2 시간 동안 교반하였다. 분지쇄아미노산를 함유한 나노서스펜션을 제조하기 위해서 70°C로 예열된 분지쇄아미노산 현탁액을 고압균질화기를 사용하여 100 MPa에서 5 회 균질화를 진행하였다. pH에 관계없이 고압균질화를 통해 분지쇄아미노산의 가용성을 증가되었지만, 가용성이 장기간 동안 유지 되지 않았다. 분산안정제에 의해 분지쇄아미노산의 포화 농도는 증가하였고, 분지쇄아미노산의 포화 농도 증가에 대한 안정제의 영향은 pH 6에서 더 확연했다. pH 6에서 Tween 80은 분지쇄아미노산와의 혼합 비율과는 무관하게 분지쇄아미노산 nanosuspension의 저장안정성을 크게 증가 시켰지만, pH 3에서는 그렇지 않았다. 그러나 lysolecithin과 Span 80을 적용한 분지쇄아미노산 nanosuspension의 저장안정성은 pH와 안정제의 혼합 비율에 따라 영향을 받았다.