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Nucleation and seeding of organometal halide perovskite (OHP) films have been extensively investigated for forming high-density, large-crystalline, and low-defect films. In this study, CH3NH3PbBr3 (MAPbBr3) films with a low defect density are synthesized via a molecular exchange mechanism using MAPbBr3 quantum dots as seeds. The synthesized films exhibit a pyramidal morphology with a (111) crystal plane. The distribution of the (111) plane is controlled by adjusting the seed concentration. The pyramidal MAPbBr3 films exhibit improved photoluminescence intensity and uniformity compared with films produced using seedless toluene. When the seeds are employed, the surface trap density is reduced by a factor of 3.5, suppressing the photocurrent hysteresis and nonsaturated response of photodetectors. Additionally, the films formed using the seeds have improved stability owing to the chain decomposition reaction induced by electron beam heating.

Transition metal dichalcogenides (TMDCs) are promising two-dimensional (2D) materials for realizing next-generation electronics and optoelectronics with attractive physical properties. However, monolayer TMDCs (

Various functional devices including p-n forward, backward, and Zener diodes are realized with a van der Waals heterostructure that are composed of molybdenum disulfide (MoS

Metal-nanowire such as silver nanowire (AgNW) is widely studied as a promising candidate for replacement of indium-tin-oxide (ITO)-based transparent conducting electrodes (TCEs) in LEDs. However, the efficiency of LEDs with metal nanowire is inferior to that of LEDs with ITO due to high contact resistance, low current spreading and high absorption in visible range. To solve these problems, we demonstrate localized surface plasmon Ag NW + nanoparticle (NP)-based TCEs where internal quantum efficiency (IQE) is improved by quantum well (QW)-LSP coupling and light extraction efficiency (LEE) is enhanced by NPs working as leak mode and scattering center.

Molybdenum disulfide (MoS2) is rapidly emerging in a wide range of applications owing to its superior optical, electrical, and catalytic properties. In particular, aside from the current great interest in monolayer MoS2, MoS2 quantum dots (QDs) have received much attention in the electronics and optoelectronics fields owing to their inherent electrical and optical properties arising from the quantum confinement effect. Thus, various methods for producing MoS2 QDs, such as exfoliation, substrate growth, and colloidal synthesis, have been attempted. In this study, the method for manufacturing MoS2 QD with a size of 10 nm which is simpler than the conventional method was devised. On the basis of characterization of the prepared MoS2 QD samples, resistive switching devices was fabricated. These devices demonstrated stable unipolar resistive switching behavior without an electroforming process. This study provides a new approach for the mass production of MoS2 QD and one of their potential applications.

Two-dimensional transition-metal dichalcogenides (TMDCs) are notable materials owing to their flexibility, transparency, and appropriate bandgaps. Because of their unique advantages, TMDC p-n diodes have been studied for next-generation electronics and optoelectronics. However, their efficiency must be increased for commercialization. In this study, we demonstrated a heterostructure composed of few-layer ReS2 and WSe2. This few-layer ReS2/WSe2 heterostructure exhibits a p-n junction and an n-n junction in different gate-bias regimes. In the p-n junction regime, the heterostructure shows outstanding rectification behavior. Additionally, we identify three carrier-transfer mechanisms - direct tunneling, Fowler-Nordheim tunneling, and the space charge region - depending on the drain bias. Furthermore, the photovoltaic effect is observed in this few-layer ReS2/WSe2 heterostructure. As a result, a high fill factor (≈ 0.56), power conversion (≈ 1.5%), and external quantum efficiency (≈ 15.3%) were obtained. This study provides new guidelines for flexible optoelectronic devices.

The Ids-Vds properties of a van der Waals cross-junction of few layered MoS2/MoTe2 were investigated, and the physical device parameters were altered in order to transform the conduction mechanism from thermionic emission to interband tunneling. The pristine heterostructure demonstrated rectification behavior of typical p-n junction diodes, because of the p-type and n-type nature of MoTe2 and MoS2, respectively. Lowering the contact resistance between the metal and channel materials, by changing the electrode metals from Au to Pd and Ti, alone did not give rise to carrier conduction through the hetero-interband tunneling between MoTe2 and MoS2. In addition to the reduction in contact resistance, the chemical doping of MoS2 using Benzyl Viologen (BV) achieves hetero-interband tunneling between MoTe2 and MoS2, which probably narrows the depletion layer by degenerating MoS2. The peak-to-valley ratio of the tunneling current of the BV-doped heterostructure of MoS2/MoTe2 is about 4.8, which is comparable to that of the commercially available Si tunneling diode.

Background Thiopental and propofol have been widely used for general anesthesia induction, but their impacts on cardiac function have not been well described. A recent study speculated that anesthesia induction using propofol 2 mg/kg transiently reduced left ventricular (LV) contraction by analyzing tissue Doppler-derived imaging (TDI) during induction phase. The purpose of this study was to analyze and to compare the impacts of propofol- and thiopental-induction on LV function. Methods Twenty-four female patients with normal LV function undergoing non-cardiac surgery were randomly administered intravenous bolus thiopental (5 mg/kg, Thiopental-group, n = 12) or propofol (2 mg/kg, Propofol-group, n = 12) for anesthesia-induction. TDI of septal mitral annular velocity during systole (S'), early diastole (e') and atrial contraction (a') were determined by transthoracic echocardiography before and 1, 3, and 5 minutes after thiopental/propofol administration (T0, T1, T2, and T3, respectively). Results The bispectral index and systolic blood pressure declined significantly during anesthesia induction in both groups, however, more depressed in Thiopental-group compared with those in Propofol-group at T2 and T3 (all, p < 0.05). Among TDI two parameters demonstrated a significant inter-group difference: the S' in propofol was lower than that in Thiopental-group at T3 (p = 0.002), and a' velocities were persistently lower in Propofol-group, compared with same time values in Thiopental-group (T1, T2, and T3: p = 0.025, 0.007, and 0.009, respectively). Conclusion Anesthesia induction using propofol revealed a more persistent and profound decline of LV and atrial contraction than that using thiopental. Further studies are needed to understand the clinical implication.