A streamlined algorithm for two-dimensional bandgaps and defect-state energy variations in InGaN-based micro-LEDs.

Bandgaps and defect-state energies are key electrical characteristics of semiconductor materials and devices, thereby necessitating nanoscale analysis with a heightened detection threshold. An example of such a device is an InGaN-based light-emitting diode (LED), which is used to create fine pixels in augmented-reality micro-LED glasses. This process requires an in-depth understanding of the spatial variations of the bandgap and its defect states in the implanted area, especially for small-sized pixelation requiring electroluminescence.

SrTiO and (Ba,Sr)TiO Films Epitaxially Grown on SrRuO Using Atomic Layer Deposition.

High dielectric constant () materials have been investigated to improve the performance of dynamic random access memory (DRAM) capacitors. However, the conventional binary oxides have reached their fundamental limit of < 100. In this study, we investigated alternative ternary oxides, SrTiO (STO) and (Ba,Sr)TiO (BSTO), which were epitaxially grown on SrRuO (SRO) using atomic layer deposition (ALD).

Mechanism for Local-Atomic Structure Changes in Chalcogenide-based Threshold-Switching Devices.

Threshold-switching devices based on amorphous chalcogenides are considered for use as selector devices in 3D crossbar memories. However, the fundamental understanding of amorphous chalcogenide is hindered owing to the complexity of the local structures and difficulties in the trap analysis of multinary compounds. Furthermore, after threshold switching, the local structures gradually evolve to more stable energy states owing to the unstable homopolar bonds.

Dual Chalcogen-Bonding Interaction for High-Performance Filterless Narrowband Organic Photodetectors.

A novel green-absorbing organic molecule featuring dual intramolecular chalcogen bonds is synthesized and characterized. This molecule incorporates two such bonds: one between a tellurium atom and the oxygen atom of a carbonyl moiety, and the other between the tellurium atom and the adjacent nitrogen atom within a pyridine moiety. The molecule, featuring dual intramolecular chalcogen bonds exhibits a narrow absorption spectrum and elevated absorption coefficients, closely aligned with a resonance parameter of approximately 0.

Effect of trifluoroacetic acid on InP/ZnSe/ZnS quantum dots: mimicking the surface trap and their effects on the photophysical properties.

Understanding the precise effects of defects on the photophysical properties of quantum dots (QDs) is essential to their development with near-unity luminescence. Because of the complicated nature of defects in QDs, the origins and detailed roles of the defects still remain rarely understood. In this regard, we used detailed chemical analysis to investigate the effect of surface defects on the optical properties of InP/ZnSe/ZnS QDs by introducing shell defects through controlled trifluoroacetic acid (TFA) etching.

Bevel Structure Based XPS Analysis as a Non-Destructive Chemical Probe for Complex Interfacial Structures of Organic Semiconductors.

The bevel structure of organic multilayers produced by finely controlled Ar gas cluster ion beam sputtering preserves both the molecular distribution and chemical states. Nevertheless, there is still an important question of whether this method can be applicable to organic multilayer structures composed of complex or ambiguous interfaces used in real organic optoelectronic devices. Herein, various bevel structures are fabricated from different types of organic semiconductors using a solution-based deposition technique: complicatedly intermixed electron-donor and electron-acceptor bulk heterojunction structure, thin film structure with an internal donor-acceptor concentration gradient, and multi-layered structure with more than three layers.

Increasing the Energy Gap between Band-Edge and Trap States Slows Down Picosecond Carrier Trapping in Highly Luminescent InP/ZnSe/ZnS Quantum Dots.

Non-toxic InP-based nanocrystals have been developed for promising candidates for commercial optoelectronic applications and they still require further improvement on photophysical properties, compared to Cd-based quantum dots (QDs), for better device efficiency and long-term stability. It is, therefore, essential to understand the precise mechanism of carrier trapping even in the state-of-the-art InP-based QD with near-unity luminescence. Here, it is shown that using time-resolved spectroscopic measurements of systematically size-controlled InP/ZnSe/ZnS core/shell/shell QDs with the quantum yield close to one, carrier trapping decreases with increasing the energy difference between band-edge and trap states, indicating that the process follows the energy gap law, well known in molecular photochemistry for nonradiative internal conversion between two electronic states.

Silver Nanowire Network Hybridized with Silver Nanoparticle-Anchored Ruthenium Oxide Nanosheets for Foldable Transparent Conductive Electrodes.

Facile strategies in flexible transparent conductive electrode materials that can sustain their electrical conductivities under 1 mm-scale radius of curvature are required for wider applications such as foldable devices. We propose a rational design as well as a fabrication process for a silver nanowire-based transparent conductive electrode with low sheet resistance and high transmittance even after prolonged cyclic bending. The electrode is fabricated on a poly(ethylene terephthalate) film through the hybridization of silver nanowires with silver nanoparticles-anchored RuO nanosheets.

In-Depth Investigation of the Correlation between Organic Semiconductor Orientation and Energy-Level Alignment Using In Situ Photoelectron Spectroscopy.

Organic semiconductors (OSCs) are of interest for replacing traditional Si-based semiconductors as their flexibility and transparency enable new applications. The properties of OSC materials greatly depend on their orientation and molecular arrangement, which are strongly dependent on the underlying substrate material. Hence, in this study, in situ ultraviolet photoelectron spectroscopy (UPS) is used to elucidate the effect of the substrate on OSC orientation.

Antimicrobial Peptide Reverses ABCB1-Mediated Chemotherapeutic Drug Resistance.

Multidrug resistance (MDR) of tumor cells to chemotherapeutic agents is the main reason for the failure of cancer chemotherapy. Overexpression of ABCB1 transporter that actively pumps various drugs out of the cells has been considered a major contributing factor for MDR. Over the past decade, many antimicrobial peptides with antitumor activity have been identified or synthesized, and some antitumor peptides have entered the clinical practice.

Direct Printing of Asymmetric Electrodes for Improving Charge Injection/Extraction in Organic Electronics.

Engineering the energy levels of organic conducting materials can be useful for developing high-performance organic field-effect transistors (OFETs), whose electrodes must be well controlled to facilitate easy charge carrier transport from the source to drain through an active channel. However, symmetric source and drain electrodes that have the same energy levels are inevitably unfavorable for either charge injection or charge extraction. In this study, asymmetric source and drain electrodes are simply prepared using the electrohydrodynamic (EHD)-jet printing technique after the careful work function engineering of organic conducting material composites.

Direct tuning of graphene work function via chemical vapor deposition control.

Besides its unprecedented physical and chemical characteristics, graphene is also well known for its formidable potential of being a next-generation device material. Work function (WF) of graphene is a crucial factor in the fabrication of graphene-based electronic devices because it determines the energy band alignment and whether the contact in the interface is Ohmic or Schottky. Tuning of graphene WF, therefore, is strongly demanded in many types of electronic and optoelectronic devices.

Revealing Li Metal Anode Surface Evolution upon Exposure to CO Using Ambient Pressure X-Ray Photoelectron Spectroscopy.

Because they deliver outstanding energy density, next-generation lithium metal batteries (LMBs) are essential to the advancement of both electric mobility and portable electronic devices. However, the high reactivity of metallic lithium surfaces leads to the low electrochemical performance of many secondary batteries. Besides, Li deposition is not uniform, which has been attributed to the low ionic conductivity of the anode surface.

Author Correction: Surface plasmon enhanced Organic color image sensor with Ag nanoparticles coated with silicon oxynitride.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Surface plasmon enhanced Organic color image sensor with Ag nanoparticles coated with silicon oxynitride.

As organic photodetectors with less than 1 μm pixel size are in demand, a new way of enhancing the sensitivity of the photodetectors is required to compensate for its degradation due to the reduction in pixel size. Here, we used Ag nanoparticles coated with SiON as a light-absorbing layer to realize the scale-down of the pixel size without the loss of sensitivity. The surface plasmon resonance appeared at the interface between Ag nanoparticles and SiON.

Formation of microbial products by activated sludge in the presence of a metabolic uncoupler o-chlorophenol in long-term operated sequencing batch reactors.

Metabolic uncouplers are widely used for reducing excess sludge in biological wastewater treatment systems. However, the formation of microbial products, such as extracellular polymeric substances, polyhydroxyalkanoate and soluble microbial products by activated sludge in the presence of metabolic uncouplers remains unrevealed. In this study, the impacts of a metabolic uncoupler o-chlorophenol (oCP) on the reduction of activated sludge yield and formation of microbial products in laboratory-scale sequencing batch reactors (SBRs) were evaluated for a long-term operation.

Production of polyhydroxyalkanoates and enrichment of associated microbes in bioreactors fed with rice winery wastewater at various organic loading rates.

This study aimed to explore the production of polyhydroxyalkanoates (PHA) and selection of PHA-accumulating microorganisms in bioreactors fed with rice winery wastewater at various organic loading rates (OLRs). The substrate utilization, sludge properties, PHA synthesis and microbial community structure of three sequencing batch reactors were monitored. The results show the highest PHA yield (0.

Modeling the electrical resistivity of polymer composites with segregated structures.

Hybrid carbon nanotube composites with two different types of fillers have attracted considerable attention for various advantages. The incorporation of micro-scale secondary fillers creates an excluded volume that leads to the increase in the electrical conductivity. By contrast, nano-scale secondary fillers shows a conflicting behavior of the decreased electrical conductivity with micro-scale secondary fillers.

The role of defects in organic image sensors for green photodiode.

Controlling defect states in a buffer layer for organic photo devices is one of the vital factors which have great influence on the device performance. Defect states in silicon oxynitride (SiON) buffer layer for organic photo devices can be controlled by introducing appropriate dopant materials. We performed ab initio simulations to identify the effect on doping SiON with carbon (C), boron (B), and phosphorous (P) atoms.

Discovery and synthesis of sulfur-containing 6-substituted 5,8-dimethoxy-1,4-naphthoquinone oxime derivatives as new and potential anti-MDR cancer agents.

Multi-drug resistance (MDR) to anticancer drugs is the primary impediment to successful treatment of cancer. Hunting for new compounds with potent anti-MDR activity is an effectual approach to conquer cancer drug resistance. In this work, 33 new sulfur-containing 1,4-naphthoquinone oxime derivatives were prepared and investigated for their cytotoxicity against a panel of tumor cell lines and fibroblast normal cell line.

Origins of High Performance and Degradation in the Mixed Perovskite Solar Cells.

The origins of the high device performance and degradation in the air are the greatest issues for commercialization of perovskite solar cells. Here this study investigates the possible origins of the mixed perovskite cells by monitoring defect states and compositional changes of the perovskite layer over the time. The results of deep-level transient spectroscopy analysis reveal that a newly identified defect formed by Br atoms exists at deep levels of the mixed perovskite film, and its defect state shifts when the film is aged in the air.

Surface Modification of CdSe Quantum-Dot Floating Gates for Advancing Light-Erasable Organic Field-Effect Transistor Memories.

Photoresponsive transistor memories that can be erased using light-only bias are of significant interest owing to their convenient elimination of stored data for information delivery. Herein, we suggest a strategy to improve light-erasable organic transistor memories, which enables fast "photoinduced recovery" under low-intensity light. CdSe quantum dots (QDs) whose surfaces are covered with three different organic molecules are introduced as photoactive floating-gate interlayers in organic transistor memories.

Nanotube and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) composite film for the electrode applications in organic thin-film transistor and dye-sensitized solar cells.

In this study, composite films made of coiled carbon nanotubes (CCNTs) and poly(3,4-ethylenedioxythiophene) polymerized with poly(4-styrenesulfonate) (PEDOT:PSS) were fabricated with different composition ratios. The variations in film properties (including surface morphology, work function, and electrical conductivity) in accordance with the amount of CCNT dosing were investigated. Subsequently, through HCl-methanol treatment, we achieved a significant enhancement in electrical conductivity with little damage to the CCNT features.