This study examines the volatilization of alkali elements on the surfaces of ceramic targets and in the deposited films during the deposition of potassium sodium niobate (KNN) thin films using a ceramic target with the nominal composition K0.55Na0.55NbO3 via a RF magnetron sputtering process. Under a 100 W RF power condition, significant volatilization of alkali elements occurred on the surface of the ceramic target, resulting in the inevitable formation of a Nb-rich secondary phase in the thin films. However, perovskite-phase KNN thin films with excellent reproducibility and without secondary phases were obtained under 50 W RF power and a substrate temperature of 600 °C. When the RF power was reduced to 20 W or the substrate temperature was lowered to 500 °C under 50 W RF power, no crystalline thin films could be obtained. Additionally, when the substrate temperature was raised to 700 °C under 50 W RF power, the niobium-rich secondary phase appeared in the thin films due to the volatilization of alkali elements. The conditions of 50 W RF power and a substrate temperature of 600 °C were found to be optimal for depositing perovskite-phase KNN thin films. However, complete suppression of potassium volatilization from the thin films was not achievable. Consequently, the resulting films had a sodium-rich composition compared to K0.5Na0.5NbO3 and exhibited lower dielectric constants along with relaxor ferroelectric characteristics. This study highlights the importance of monitoring the compositional changes in ceramic targets during the RF sputtering process to ensure high reproducibility in KNN thin film fabrication.

Hydrogen production via photoelectrochemical water splitting relies on the effectiveness of the photoelectrodes. Preparing low-dimensional structures of oxide semiconductors is a promising approach to fabricating effective photoelectrodes, by enhancing the surface-to-volume ratios of the photocatalytic materials. In this study, we performed a comparative investigation of the photoelectrochemical characteristics of p-type oxide semiconductor cupric oxide (CuO) photocathodes based on CuO thin film and nanorods. The CuO thin film was prepared via a facile method involving sputtering a Cu metallic film and subsequent thermal oxidation, while the CuO nanorods were grown via a seed-mediated hydrothermal synthesis method using a CuO nanoparticle seed layer. The structural, optical, and photoelectrochemical properties of the prepared CuO thin film and nanorods were comparatively examined. Our results confirmed that the CuO nanorod photocathode has a higher photocurrent density and better photoconversion efficiency than the CuO thin film photocathode for photoelectrochemical water splitting, implying a promising route to the fabrication of CuO-based photoelectrodes.

고체전해질은 높은 에너지 밀도와 안전성을 갖춘 차세대 리튬이온전지에 꼭 필요한 핵심 요소다. 이러한 고체전 해질의 제작을 위해서 기존 고체전해질의 낮은 이온전도도와 높은 계면저항 문제를 해결해야 한다. 본 연구에서는 강화된 이 온 전도성과 계면 안정성을 지닌 PVDF-HFP 고분자에 분산된 Li7La3Zr2O12 (LLZO) 나노와이어 복합체를 기반으로 하는 새 로운 전해질(PVDF-HFP/LLZO/SN, PHLS membrane)을 제안한다. PHLS에 용매 열압착(Sovlent heat press, SHP)을 통해 계 면 저항과 내부 공극이 감소된 PHLS-(SHP)는 30°C에서 2.06 × 10-4 S/cm의 높은 이온 전도도, 4.5 V (vs. Li/Li+)의 넓은 전 기화학적 전위 창, 리튬 금속과 전해질 사이의 안정된 계면 안정성을 나타냈다. 0.2 mA/cm2에서 수행된 Li 대칭 셀을 사용한 전기화학적 테스트에서 150 시간 이상 안정성을 유지하는 것으로 확인되었으며, 이는 당사의 복합 기반 고체 전해질을 활용 하여 전기화학적 성능이 향상되었음을 시사한다.

This study investigates the performance characteristics of electrodeposited (ED) silver nanowires (AgNWs) networks as transparent conducting electrodes (TCEs) considering Cu(In,Ga)Se2 (CIGS) thin-film solar cells. The electrodeposition process uniformly deposits silver onto a network of spin-coated AgNWs, resulting in the enlargement of individual nanowire diameters and the formation of stronger interconnections between the AgNWs. This structural enhancement significantly improves both the electrical conductivity and thermal stability of the ED AgNW networks, making them more efficient and robust for practical applications in solar cells. The study comprehensively examines the optoelectronic properties of the ED AgNW networks, encompassing total and specular transmittance, transmission haze values, and sheet resistance, with varying durations of silver electrodeposition. Additionally, this study presents the current density (J)-voltage (V) characteristics of CIGS thin-film solar cells employing the ED AgNW TCEs, revealing how electrodeposition duration impacts overall device performance. These findings offer valuable insights for optimizing TCEs in not only thin-film solar cells but also in other optoelectronic devices, highlighting the potential for improved long-term stability across various applications without compromising performance.

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.

Nano-oxide dispersion–strengthened (ODS) superalloys have attracted attention because of their outstanding mechanical reinforcement mechanism. Dispersed oxides increase the material’s strength by preventing grain growth and recrystallization, as well as increasing creep resistance. In this research, atomic layer deposition (ALD) was applied to synthesize an ODS alloy. It is useful to coat conformal thin films even on complex matrix shapes, such as nanorods or powders. We coated an Nb-Si–based superalloy with TiO2 thin film by using rotary-reactor type thermal ALD. TiO2 was grown by controlling the deposition recipe, reactor temperature, N2 flow rate, and rotor speed. We could confirm the formation of uniform TiO2 film on the surface of the superalloy. This process was successfully applied to the synthesis of an ODS alloy, which could be a new field of ALD applications.

해당 연구는 산업 폐수에서 염료를 효율적으로 제거하기 위한 고급 박막 나노복합체(TFN) 기반 나노여과막을 개 발하여 효과적인 폐수 처리 방법을 제시합니다. 최근 연구의 동향을 보면, 나노카본, 실리카 나노스피어, 금속-유기 프레임워 크(MOF) 및 MoS2와 같은 혁신적인 재료를 포함하는 TFN 막의 제조에 중점을 둡니다. 주요 목표는 염료 제거 효율을 향상 시키고 오염 방지 특성을 개선하며 염료/염 분리에 대한 높은 선택성을 유지하는 것입니다. 이 논문은 넓은 표면적, 기계적 견고성 및 특정 오염 물질 상호 작용 능력을 포함하여 이러한 나노 재료의 뚜렷한 이점을 활용하여 현재 나노여과 기술의 제 한을 극복하고 물 처리 문제에 대한 지속 가능한 솔루션을 제공하는 것을 목표로 합니다.