High-performance self-powered photodetectors (PDs) have attracted significant interest as highly efficient optoelectronic devices capable of operating without an external power source. In this study, we demonstrate a flexible MoS2/graphene quantum dots (GQDs)/LaVO3heterojunction PD fabricated on a polyethylene terephthalate substrate. The device performance was systematically evaluated with and without the GQDs interlayer. The incorporation of GQDs effectively suppresses charge recombination, leading to substantial improvements in key performance metrics such as responsivity, external quantum efficiency, and detectivity. Furthermore, the MoS2/GQDs/LaVO3PD exhibited excellent mechanical stability, maintaining stable photocurrent and dark current levels even after 3000 continuous bending cycles. These results highlight the potential of the MoS2/GQDs/LaVO3PD as a highly promising candidate for next-generation flexible optoelectronic applications.

Porous Si (PSi) significantly enhances solar light absorption due to its porous structure, while the LaVO3 active layer strongly absorbs light across the ultraviolet to the visible spectrum. Additionally, the bathocuproine (BCP) layer improves cell efficiency by minimizing recombination losses at the silicon interface. The (trifluoromethanesulfonyl)-amide-doped graphene (TFSA-Gr) transparent conductive electrode further enhances this configuration with its high electrical conductivity and transparency. Therefore, we fabricated a TFSA-Gr/ LaVO3/PSi/Si/BCP structure to improve the efficiency and durability of Si-based solar cells. This advanced design achieved a maximum power conversion efficiency of 14.46 % and demonstrated remarkable durability by maintaining 92 % of its efficiency after 2000 h under conditions of 60 degrees C/40 % relative humidity. These results highlight the potential of this approach to significantly enhance the performance and extend the lifetime of Si-based solar cells for future photovoltaic applications.

Recently, there has been interest in developing high-performance self-driven photodetectors (PDs) using 2Dbased heterostructures due to their unique optoelectronic properties. Here, we demonstrate that verticalheterostructures based on graphene (Gr) transparent conductive electrodes, n-type 2D WS2, and p-type LaVO3 realize a broadband-responsive PD covering the wavelength range of 300-850 nm. Due to the formation of an electric field at the WS2/LaVO3 interface and the photovoltaic effect, this structure shows a rectifying operation with a maximum detectivity of 2.1 x 1010 Jones at zero bias. Additionally, it exhibits a fast fall time of 435 mu s and a 3 dB bandwidth of 2300 Hz, making it suitable for high-speed self-powered optoelectronic applications. Therefore, the TETA-Gr/WS2/LaVO3 heterojunction is proposed as an excellent candidate for high-performance, self-powered, and broadband PDs.

To manage the safety of multi-use facilities, many CCTVs and alarm sensors are used, however, they cannot replace patrol tasks to check site conditions from multiple directions. The developed rail-guided smart patrol robot helps alleviate the workload of managers by capturing images and measuring sensors at a desired location at a scheduled time in a separate space from visitors or workers. This paper proposes an adaptive patrol speed control algorithm to improve patrol performance in the facility environment. By applying the Deep Deterministic Policy Gradient (DDPG)-based learning model, the smart patrol robot can be allowed to move at an optimal speed according to the congestion of images captured in the field. The designed model can be trained by defining the reward function based on the entropy to maintain the obtained information. The proposed algorithm demonstrated performance in controlling patrol speed according to situation changes in a virtual multi-use facility environment.

Two-dimensional (2D) semiconductor and LaVO3materials with high absorption coefficients in the visible light region are attractive structures for high-performance photodetector (PD) applications. Insulating 2D hexagonal boron nitride (h-BN) with a large band gap and excellent transmittance is a very attractive material as an interface between 2D/semiconductor heterostructures. We first introduce WS2/h-BN/LaVO3semitransparent PD. The photo-current/dark current ratio of the device exhibits a delta-function characteristic of 4 × 105at 0 V, meaning 'self-powered'. The WS2/h-BN/LaVO3PD shows up to 0.27 A W-1responsivity (R) and 4.6 × 1010cm Hz1/2W-1detectivity (D*) at 730 nm. Especially, it was confirmed that theD* performance improved by about 5 times compared to the WS2/LaVO3device at zero bias. Additionally, it is suggested that the PD maintains 87% of its initialRfor 2000 h under the atmosphere with a temperature of 25 °C and humidity of 30%. Based on the above results, we suggest that the WS2/h-BN/LaVO3heterojunction is promising as a self-powered optoelectronic device.

Semitransparent solar cells are attracting attention not only for their visual effects but also for their ability to effectively utilize solar energy. Here, we demonstrate a translucent solar cell composed of bis(trifluoromethane sulfonyl)-amide (TFSA)-doped graphene (Gr), graphene quantum dots (GQDs), and LaVO3. By introducing a GQDs intermediate layer at the TFSA-Gr/LaVO3 interface, we can improve efficiency by preventing carrier recombination and promoting charge collection/separation in the device. As a result, the efficiency of the GQDs-based solar cell was 4.35%, which was higher than the 3.52% of the device without GQDs. Furthermore, the average visible transmittance of the device is 28%, making it suitable for translucent solar cells. The Al reflective mirror-based system improved the power conversion efficiency by approximately 7% compared to a device without a mirror. Additionally, the thermal stability of the device remains at 90% even after 2000 h under an environment with a temperature of 60 degrees C and 40% relative humidity. These results suggest that TFSA-Gr/GQDs/LaVO3-based cells have a high potential for practical use as a next-generation translucent solar energy power source.

LaFeO 3 film is an intermediate charge transfer/Mott–Hubbard insulator. LaFeO 3 thin films were grown on SrTiO 3 substrates using radio frequency magnetron sputtering deposition method at 500 °C. After growth, the LaFeO 3 thin films were annealed in air at 800 °C for 2 h. The LaFeO 3 films grown on SrTiO 3 substrates showed atomically sharp interfaces even though they were grown using a sputtering deposition. LaFeO 3 films show orthorhombic structures according to X-ray diffraction measurements. We obtained the dielectric functions ( ε = ε 1 + ε 2 ) of the thin films using spectroscope ellipsometry and obtained the optical gap energies from the absorption coefficients ( α = 4 πk/λ ). The optical gap energy of LaFeO 3 thin films was determined to be an indirect gap energy of 2.21 eV, and a direct gap energy of 2.73 eV. Forbidden direct gap energy was estimated to be 1.94 eV for LaFeO 3 thin films. The critical point (CP) energies were determined using the second-order energy derivative spectra of the dielectric functions. The optical gap energies and the CP energies were compared to band structure calculations in the literature.

Semi-transparent (ST) solar cells are attracting a lot of attention among researchers as they can effectively utilize solar energy in various fields such as building-integrated solar power generation and portable solar chargers.

The Apdong Nb-Ta deposit is hosted within the syenite and in the Hoamsan area in the northern part of the Imjingang Belt in North Korea. Our new sensitive high-resolution microprobe zircon U-Pb results reveal two stages of Neoproterozoic to Ordovician inherited cores (887 Ma to 465 Ma) and Silurian emplacement and mineralization (425.5 +/- 7.4 Ma) events. The zircon grains from the Apdong syenite show typical magmatic or textureless and sponge-like hydrothermal domains. These textural analyses supported the rare earth element characteristics obtained from the laser ablation-induced coupled plasma mass-spectrometry analyses (LA-ICP-MS). Neoproterozoic magmatic activities reportedly occur in the Pyeongnam Basin, Imjingang Belt [present study], Gyeonggi Massif, and Okcheon metamorphic belt in the central part of the Korean Peninsula and China (North China Craton, Qinling Orogenic Belt, and South China Craton). Notably, the Caledonian mineralization events in the southeastern part of the South China Craton coincided with emplacement and mineralization ages from the Apdong syenite (425.5 +/- 7.4 Ma). The LA multi-collector ICP-MS Hf isotope of zircons from the Apdong syenite yielded positive initial epsilon Hf values plotted along the Neoproterozoic crustal evolution path, indicating that the host rock of Nb-Ta ore was formed from the pre-existing Neoproterozoic source. The source materials of Neoproterozoic intrusives in the central part of the Korean Peninsula were generally derived from Meso-proterozoic depleted mantle sources. Considering the previously reported Hf isotopic results, the involvement of pre-existing crustal materials is more prominent in the Neoproterozoic intrusives in the southern part of the central Korean Peninsula, i.e., the Gyeonggi Massif, than in the northern part of the central Korean Peninsula, such as the Imjingang Belt and Pyeongnam Basin in the northern part of the central Korean Peninsula.

Diagnosis of the semiconductor defect levels is essential for their device applications. The optical and electrical properties of Ga2-xSnxO3 (GTO, 0 < x < 0.7) films were investigated to look into the defect levels. Amorphous GTO thin films were grown on Si substrates with various Sn contents via radio frequency magnetron sputtering deposition. Thermal annealing at 900 degrees C for two hours was performed after the deposition of films at 500 degrees C to achieve the polycrystalline phase. We examined the physical properties of amorphous beta-Ga2O3 thin films grown using various O2 gas flows during growth, and of the post-annealed GTO films. Using spectroscopic ellipsometry, the optical constants in the spectral range between 1.0 and 6.0 eV were determined. We estimated the optical gap energy of the GTO layers using the Tauc method. The optical gap energy was approximately 4.9 eV for amor-phous beta-Ga2O3 films. Optical structures owing to defects were found below optical gap energy in the spectra of the complex refractive index. Using cathodoluminescence (CL) spectroscopy, there were several peaks discovered in the range between 1.5 and 3.0 eV. The CL peaks correspond to transitions between valence (conduction band) and defect-induced gap states. We identified the 1.5 -1.6 eV peak as the transition between defect states and the conduction band. The extinction coefficient (k) peak became sharper at 5.3 eV suggesting a strong excitonic behavior at the fundamental gap for amorphous Ga2O3 films.

This paper describes the design and implementation of a rail-guided mobile robot-based monitoring system that can be used for autonomous monitoring of the facilities and rapid response to the on-site event. It is necessary to improve the safety and efficiency of the monitoring system when applying a robot system, and the implementation of intelligent functions can increase the level of automation to facilitate operation. In order to increase driving safety and lower the level of control, a two-track rail structure of circular pipes, U-shaped wheels, and a differential gear are used to develop a driving system that enables rotational path driving even with forward and backward movement. For the proper monitoring of facility conditions, high-temperature occurrence, and environmental quality, cameras (RGB and thermal imaging) and air quality sensors are chosen by considering the range of the monitoring site and target subjects. Data communication between the robot and the remote control room(a remote server) is built up to patrol in a planned schedule and deliver acquired video streams and environmental sensor data. Emergency alarms about high temperatures and the abnormality of air conditions can be generated by processing the transferred data. Additionally, deep network-based detection services on video data are implemented on the server for the detection of emergency situations; fall downs. Integrating the developed driving system, image/sensor data communication, and alarm function through data analysis in an operating framework reduces management work through automatic patrol and enables efficient on-site response when an alarm occurs. The validity of the proposed system is demonstrated by building and operating the system in the existing multi-use facility. The automatic patrol function and the manual operation function are performed through a test operation similar to the facility monitoring task of a human operator. The operator can control the robot to move to a desired position along the path, and by manipulating the camera module, the operator can check the on-site situation via a video stream The environmental sensor data is also transferred to the server and stored during operation, and the robot normally completes the automatic patrol task and returns to the charging station. In a simulation experiment to verify the detection alarm service, the test shows that a human falling down is detected even in the field.

To effectively utilize solar energy, semitransparent solar cells are essential in various fields such as building-integrated solar power generation and portable solar chargers. We report triethylenetetramine (TETA)-doped graphene (Gr) transparent conductive electrode (TCE)-based LaVO3 semitransparent solar cells. To optimize the Gr TCE, we varied the TETA molar concentration (nD) from 0.1 to 0.3 mM. TETA-doped Gr (TETA-Gr)/LaVO3 semitransparent solar cells exhibit the highest 1.45% efficiency and 62% average visible transmittance at nD = 0.2 mM. These results indicate that the TETA-Gr/LaVO3 structure not only harvests solar energy in the ultraviolet-visible region but also exhibits translucency, thanks to the thin film. Thanks to its translucent properties, we improved the power conversion efficiency (PCE) to 1.99% by adding an Al reflective mirror to the semitransparent cells. Finally, the device's PCE loss is only within 3% for 3000 h in air, suggesting good durability.

The combination of a high absorption LaVO3 in the visible region and two-dimensional semiconductor material is an ideal structure for high-performance broadband photodetector (PD) applications. We report MoS2/LaVO3 heterojunction PDs. The p-n junctions were found to show good PD properties, including a photocurrent/dark current ratio of 104 at zero voltage, indicating "self-powered." The PDs exhibit a re-sponsivity (R) of 0.14 AW-1 and a detectivity of 4.5 x 109 cm Hz1/2 W-1 at 650 nm. The linear dynamic range and response/recovery times of the PDs are 83 dB and 260/410 mu s, respectively. Notably, the response time of the PDs is faster than those of previously reported chemical vapor deposition MoS2-based hetero-structured PDs. Furthermore, the loss of the R is only 16% of its initial value, whereas the PDs are kept for 2000 h in the air. Additionally, the R loss of the PD decreases by only 16% of its original value during 2000 h under air at 25 degrees C temperature and 30% humidity. These results demonstrate the potential of MoS2/LaVO3 heterojunctions as self-powered optoelectronic devices.(c) 2022 Elsevier B.V. All rights reserved.

The strong correlation effect in Weyl semimetal is a critical issue in condensed matter physics. Recently, the Kondo effect in Weyl semimetal was theoretically proposed but not yet experimentally realized. Here we suggest a coexistence of the Weyl semimetal and Kondo effect in disordered Mn-doped MnxVAl3. Dilute Mn-doping in type-II Dirac semimetal VAl3 increases the chemical potential so that Dirac point is close to the Fermi energy and lifts band degeneracy, leading to the Weyl semimetal phase transition. We observed a Kondo effect, confirmed by the resistivity minimum at T-K = 40 K, and logarithmic increase of electrical resistivity, magnetic susceptibility, and specific heat divided by temperature with a significant Sommerfeld coefficient at low temperature. The angle-resolved magnetoresistance has revealed the negative longitudinal magnetoresistance below Kondo temperature due to chiral anomaly in Mn-doped MnxVAl3. At low temperature below Kondo temperature (T <= T-K), the exchange interaction by RKKY interaction in MnxVAl3 breaks time-reversal symmetry even in Kondo screening, resulting in the topological phase transition from Dirac to Weyl semimetal. This research shows the coexistence of the Kondo effect and Weyl semimetallic state as well as the temperature-induced topological phase transition.

Sn-doped In2O3 (ITO) films are in high demand for use as transparent electrodes in optoelectronic devices. Technological developments have improved the quality of ITO films, and a detailed investigation of their properties is desired. Therefore, we investigated the composition dependence of the electrical and optical properties of (In1-xSnx)(2)O3(1+delta) films (with 0.03 <= x <= 0.40 and delta approximate to 0.28) films grown on Si and glass substrates utilizing the co-sputtering of In2O3 and SnO2 targets. Using X-ray diffraction, we found that the In2O3-like (222) phase was the dominant phase for x = 0.03. Further, the In2Sn2O7+x (400) phase became the dominant phase as the Sn concentration increased. This work demonstrates that ITO films exhibit excellent transmittance properties (T approximate to 88.3%) in the visible range as well as very low resistivities (rho approximate to 2 x 10(-4) Omega cm), regardless of the Sn composition. However, ITO films with Sn = 0.11, the commercially used composition, exhibited the lowest transmittance in the near-infrared range, 73.7%, whereas other ITO films showed large transmittances in the near-infrared range: T = 90.9% at x = 0.03 and T = 85.7% at x = 0.40.

LaVO3 is well known as a promising material for use in photovoltaic devices because of its high absorption of visible light. Here, we report on the photovoltaic parameters and photostability of LaVO3/Si/TiOx solar cell devices. In this work, the photovoltaic parameters of the device are controlled via the thickness (t) of the LaVO3 layer; such control is possible because the transmittance, absorbance, and reflectance of this layer are dependent on its thickness. TiOx passivation is also used to reduce the recombination loss at the back surface. Furthermore, TiOx passivation improves the power conversion efficiency (PCE) by blocking re-combination at the Si/metal interface. The LaVO3/Si/TiOx cells exhibit a maximum PCE of 6.78% at t = 70 nm. The PCE of the device shows only a 9% decrease after continuous 500 h irradiation at an intensity of 100 mW cm(-2) at a temperature of 60 degrees C and 30-35% relative humidity, suggesting excellent long-term stability. (C) 2022 Elsevier B.V. All rights reserved.