Surmounting Erase-Operation Limit in Organic Charge-Trap Memories by Fine Tuning Electron Injection at Semiconductor/Heterobimetallic Electrode Contacts.

Heterobimetallic systems (HBS), known for their ability to facilitate the versatile design of surface workfunctions, offer significant potential as an electron-injection electrode layer for organic semiconductors. In this paper, we propose a universal and effective strategy to overcome the limitations of the erase operation in charge-trap memory with a small-bandgap organic semiconductor or diketopyrrolopyrrole-quaterthiophene-conjugated polymer (PDPP4T) by utilizing HBS-based source/drain (SD) electrodes. Conventional gold SD electrodes restrict electron injection into the PDPP4T layer during the electrical erase operation and impose a lower limit on the erasing voltage required for full threshold-voltage recovery.

Effect of Gate Bias Stress on the Electrical Characteristics of Ferroelectric Oxide Thin-Film Transistors with Poly(Vinylidenefluoride-Trifluoroethylene).

We investigated the effect of gate bias stress (GBS) on the electrical characteristics of ferroelectric oxide thin-film transistors (FeOxTFTs) with poly(vinylidenefluoride-trifluoroethylene). Generally, conventional oxide thin-film transistors (OxTFTs) with dielectric gate insulators exhibit a small negative shift under negative gate bias stress (NBS) and a large positive shift under positive gate bias stress (PBS) in transfer characteristic curves. In contrast, the FeOxTFTs show a small positive shift and a large negative shift under NBS and PBS, respectively.

A Dew-Condensation Sensor Exploiting Local Variations in the Relative Refractive Index on the Dew-Friendly Surface of a Waveguide.

We propose a sensor technology for detecting dew condensation, which exploits a variation in the relative refractive index on the dew-friendly surface of an optical waveguide. The dew-condensation sensor is composed of a laser, waveguide, medium (i.e.

Fabrication of Multi-Layer Metal Oxides Structure for Colored Glass.

This study proposes front colored glass for building integrated photovoltaic (BIPV) systems based on multi-layered derivatives of glass/MoO/AlO with a process technology developed to realize it. Molybdenum oxide (MoO) and aluminum oxide (AlO) layers are selected as suitable candidates to achieve thin multi-layer color films, owing to the large difference in their refractive indices. We first investigated from a simulation based on wave optics that the glass/MoO/AlO multi-layer type offers more color design freedom and a cheaper fabrication process when compared to the glass/AlO/MoO multi-layer type.

Effect of Buffer Layer Capacitance on the Electrical Characteristics of Ferroelectric Polymer Capacitors and Field Effect Transistors.

We demonstrated the effect of a buffer layer on the electrical characteristics of ferroelectric polymer capacitors and field-effect transistors. Various polymer materials with a dielectric constant between 2 and 42 were used to form buffer layers with a similar thicknesses, but with different capacitances. In order to evaluate the characteristics of the ferroelectrics with a buffer layer, the polarization-voltage characteristics of the capacitor, the transfer characteristics, and the retention characteristics of the transistors were investigated.

Enhancement of Charge Injection in Organic Field-Effect Transistors Through Semiconducting Organic Buffer Layer.

We investigate the effect of a semiconducting organic buffer layer (SOBL) on the injection and transport of charges in organic field-effect transistors (OFETs). Here, two different injection barriers at the source/organic semiconductor interface are respectively studied with the aid of a numerical simulation: one is intermediate (0.4 eV), and the other is large energy barriers (0.

Enhancement of the Retention Characteristics in Solution-Processed Ferroelectric Memory Transistor with Dual-Gate Structure.

We demonstrated the enhancement of the retention characteristics in solution-processed ferroelectric memory transistors. For enhanced retention characteristics, solution-processed Indium Gallium Zinc Oxide (InGaZnO) semiconductor is used as an active layer in a dual-gate structure to achieve high memory on-current and low memory off-current respectively. In our dual-gate oxide ferroelectric thin-film transistor (DG Ox-FeTFT), while conventional TFT characteristic is observed during bottom-gate sweeping, large hysteresis is exhibited during top-gate sweeping with high memory on-current due to the high mobility of the InGaZnO.

Reliable organic memristors for neuromorphic computing by predefining a localized ion-migration path in crosslinkable polymer.

In flexible neuromorphic systems for realizing artificial intelligence, organic memristors are essential building blocks as artificial synapses to perform information processing and memory. Despite much effort to implement artificial neural networks (ANNs) using organic memristors, the reliability of these devices is inherently hampered by global ion transportation and arbitrary growth of conductive filaments (CFs). As a result, the performance of ANNs is restricted.

Realization of Biomimetic Synaptic Functions in a One-Cell Organic Resistive Switching Device Using the Diffusive Parameter of Conductive Filaments.

Toward the successful development of artificial intelligence, artificial synapses based on resistive switching devices are essential ingredients to perform information processing in spiking neural networks. In neural processes, synaptic plasticity related to the history of neuron activity plays a critical role during learning. In resistive switching devices, it is barely possible to emulate both short-term plasticity and long-term plasticity due to the uncontrollable dynamics of the conductive filaments (CFs).

Improvement of Photoresponse in Organic Phototransistors through Bulk Effect of Photoresponsive Gate Insulators.

In this study, we investigate the bulk effect of photoresponsive gate insulators on the photoresponse of organic phototransistors (OPTs), using OPTs with poly(4-vinylphenol) layers of two different thicknesses. For the photoresponse, the interplay between the charge accumulation (capacitance) and light-absorbance capabilities of a photoresponsive gate insulator was investigated. Although an OPT with a thicker gate insulator exhibits a lower capacitance and hence a lower accumulation capability of photogenerating charges, a thicker poly(4-vinylphenol) layer, in contrast to a thinner one, absorbs more photons to generate more electron-hole pairs, resulting in a higher photoresponse of the device.

Enhanced Optical Switching Characteristics of Organic Phototransistor by Adopting Photo-Responsive Polymer in Hybrid Gate-Insulator Configuration.

In this study, we developed polymer gate insulator-based organic phototransistors (p-OPTs) with improved optical switching properties by using a hybrid gate insulator configuration. The hybrid gate insulator of our p-OPT has a photoresponsive layer made of poly(4-vinylphenol) (PVP), which enhances the photoresponse, and an interfacial layer of poly(methyl methacrylate) for reliable optical switching of the device. Our hybrid gate insulator-equipped p-OPT exhibits well-defined optical switching characteristics because no specific type of charge is significantly trapped at an interfacial layer/organic semiconductor (OSC) interface.

Solution-Processed Organic and Oxide Hybrid CMOS Inverter for Low Cost Electronic Circuits.

We demonstrated an organic and oxide hybrid CMOS inverter with the solution-processed semiconductor and source/drain electrodes. For the solution-processed - and -type semiconductor, InGaZnO solution and TIPS-pentacene/PMS blend were spin-coated respectively while Silver ink and PEDOT:PSS solution were drop-casted with the help of the bank to serve as source/drain electrodes. The InGaZnO and the TIPS-pentacene transistors show typical - and -type transistor operations with low off-current.

Interfacial Triggering of Conductive Filament Growth in Organic Flexible Memristor for High Reliability and Uniformity.

We demonstrate the physical pictures of the localization of the conductive filaments (CFs) growth in flexible electrochemical metallization (ECM) memristors through an interfacial triggering (IT) into the polymer electrolyte. The IT sites (ITSs), capable of controlling the pathways of the CF growth, are formed at the electrode-polymer interfaces via the Ostwald ripening at low temperatures (below 230 °C). The injection and migration of metal ions and the resultant CF growth are found to be effectively controlled through the ITSs with the local electric field enhancement.

Ferroelectric-Dielectric Mixed Buffer Layer for Enhanced Electrical Performance of Organic Ferroelectric Memory Transistors.

We suggest a facile method to reduce the surface roughness of the ferroelectric polymer insulator to enhance the electrical performance of the ferroelectric field effect memory transistors (FeFET). Ferroelectric-dielectric mixed buffer layer was used to reduce the high surface roughness of the single layer ferroelectric polymer insulator. The FeFET with mixed buffer bilayer (BL-FeFET) showed more than 25 times higher on-current (3.

Importance of Effective Surface Smoothness on the Electrical Performance of Organic Thin-Film Transistors.

We presented further analysis to explain how the surface morphology influence the mobility of the organic thin film transistors with gate insulator having large undulated surface (GU-OTFTs) and introduced a new parameter in order to clearly understand the relation between surface roughness and field-effect mobility. The average of the slope between two adjacent points on the surface of a gate insulator, or effective surface smoothness (ES), was closely investigated. A smooth-contact-pressing (SCP) process affected the surface smoothness of the P(VDF-TrFE) insulator with a significant change in root-mean-square roughness (Zrms).

Dynamic Manipulation of Charged Lipids in Model Membrane for Bio-Microarrays.

We describe the dynamic manipulation of the charged lipids in a confined geometry where two dispersive factors arising from the random diffusion-based Brownian motion and the field-induced drift of target lipids compete with each other. It is found that the lateral distribution of the target lipids is well controlled through a combined effect of an external electric field and the geometric restrictions by the confinement. The dynamic manipulation scheme for the charged lipids in two-dimension would be useful for understanding the spatial organization of membrane components in a supported lipid membrane mimicking a real cell membrane and for producing membrane-based microarrays.

Are Urologists Performing Semi-rigid Ureteroscopic Lithotripsy Safe From Radiation Exposure? A Guidance to Reduce the Radiation Dose.

Objective: To measure radiation exposure of urologists during ureteroscopic (URS) lithotripsy, and hence estimating the number of procedures that can be performed safely considering the annually permissible radiation dose, and to identify influential variables.

Materials And Methods: The radiation exposure dose was measured at the neck, chest, arm, and hands of a single urologist who performed 49 URS lithotripsies. The number of annually performed URS lithotripsies was estimated based on the annual permissible occupational exposure radiation dose guidelines.

Nanoparticle scattering layer for improving light extraction efficiency of organic light emitting diodes.

Nanoparticle scattering layer based on polymer-metal oxide composite is successfully introduced to enhance the light extraction efficiency of organic light emitting diodes (OLEDs). We find that the density and the distribution of nanoparticles is the key factor to maximize the light extraction efficiency of pristine OLEDs by out-coupling the unusable light with the scattering film. In our experiment, 71 wt% of Al(2)O(3) mixed with polymer matrix shows the increase of light extraction efficiency of 40%.

Quasi-surface emission in vertical organic light-emitting transistors with network electrode.

We demonstrate a vertical-type organic light-emitting transistor (VOLET) with a network electrode of closed topology for quasi-surface emission. In our VOLET, the spatial distribution of the surface emission depends primarily on the relative scale of the aperture in the network electrode to the characteristic length for the charge carrier recombination. Due to the closed topology in the network of the source electrode, the charge transport and the resultant carrier recombination are substantially extended from individual network boundaries toward the corresponding aperture centers in the source electrode.

Array of solid-state dye-sensitized solar cells with micropatterned TiO2 nanoparticles for a high-voltage power source.

We demonstrate an array of solid-state dye-sensitized solar cells (SS-DSSCs) for a high-voltage power source based on micropatterned titanium dioxide nanoparticles (TNPs) as photoanodes connected in series. The underlying concept of patterning the TNP of a few micrometers thick lies on the combination of the lift-off process of transfer-printed patterns of a sacrificial layer and the soft-cure treatment of the TNP for fixation. This sacrificial layer approach allows for high pattern fidelity and stability, and it enables to construct stable, micrometer-thick, and contamination-free TNP patterns for developing the SS-DSSC array for miniature high-voltage applications.