Bright hybrid white light-emitting quantum dot device with direct charge injection into quantum dot

A bright white quantum dot light-emitting device （white-QLED） with 4-[4-（1-phenyl-lH-benzo[d]imidazol-2- yl）phenyl]-2- [3-（tri-phenylen-2-yl）phen-3-yl]quinazoline deposited on a thin film of mixed green/red-QDs as a bilayer emitter is fabricated. The optimized white-QLED exhibits a turn-on voltage of 3.2 V and a maximum brightness of 3660 cd/m2 @8 V with the Commission Internationale de l＇Eclairage （CIE） chromaticity in the region of white light. The ultra-thin layer of QDs is proved to be critical for the white light generation in the devices. Excitation mechanism in the white-QLEDs is investigated by the detailed analyses of electroluminescence （EL） spectral and the fluorescence lifetime of QDs. The results show that charge injection is a dominant mechanism of excitation in the white-QLED.

Evolution of Diagenetic Fluid of the Dawsonite-Bearing Sandstone in the Jiyang Depression,Eastern China

Based on the petrology,isotope geochemistry and fluid inclusions analysis,we established the evolutionary mode of the diagenetic fluid of dawsonite-bearing sandstone in the Jiyang Depression.Dawsonite-bearing sandstone is characterized by double injection of CO_(2)and oil-gas in the Jiyang Depression that have experienced a relatively complex diagenetic fluid evolution process.The diagenetic sequence of secondary minerals involves secondary enlargement of quartz,kaolinite,first-stage calcite,dawsonite,second-stage calcite,ferrocalcite,dolomite and ankerite.Hydrocarbon charging in the dawsonite-bearing sandstone occurred at around 2.6–0 Myr.The CO_(2)charging event occurred during Dongying tectonism,forming the Pingfangwang CO_(2)gas reservoir,which provided an abundant carbon source for dawsonite precipitation.Carbon and oxygen isotopic compositions of dawsonite demonstrate that CO_(2)forming the dawsonite was of an inorganic origin derived from the mantle,and that water mediating the proc-ess during dawsonite precipitation was sequestered brine with a fluid temperature of 82℃.The evolutionary sequence of the diagenetic fluid in the dawsonite-bearing sandstone was:alkaline syngenetic fluids,weak alkaline fluids during organic acid forma-tion,acidic fluids in the early stage of CO_(2)injection,alkaline fluids in the late stage of CO_(2)injection,and weak alkaline fluids during oil and gas charging.The mode indicates an increase in-HCO_(3)because of the CO_(2)injection,and the loss of Ca^(2+)and Mg^(2+)due to the precipitation of carbonate minerals.Therefore,the evolutionary mode of diagenetic fluids is in good agreement with high HCO_(3)^(-),low Ca^(2+)and low Mg^(2+)composition of the present formation water in the dawsonite-bearing sandstone.

A molecular cobaloxime cocatalyst and ultrathin FeOOH nanolayers co-modifiedBiVO_(4) photoanode for efficient photoelectrochemical water oxidation

BiVO_(4) has been attracting a lot of interest in photoelectrochemical (PEC) water oxidation due to its efficient solar absorption and appropriate band positions.So far,sluggish water oxidation kinetics and fast photogenerated charge recombination still hinder the PEC performance ofBiVO_(4) .In this study,a novel PEC photoanode was designed by depositing ultrathin FeOOH nanolayers on the surface of nanoporousBiVO_(4) electrode,followed by modification with a cobaloxime (Co(dmgH)_(2)(4-COOH-py)Cl) molecular cocatalyst.Under irradiation of a 100 mW cm^(-2)(AM 1.5G) Xe lamp,the photocurrent density of the cobaloxime/FeOOH/BiVO_(4) composite photoanode reached 5.1 mA cm^(-2)at 1.23 V vs.RHE in 1.0 M potassium borate buffer solution (pH=9.0).The onset potential of the optimal cobaloxime/FeOOH/BiVO_(4) photoanode exhibited a 460 m V cathodic shift relative to bareBiVO_(4) .In addition,the surface charge injection efficiency of the composite photoanode reached~80%at 1.23 V vs.RHE and the incident photon-to-current efficiency (IPCE) reached~88%at 420 nm.

Improved Performance of Organic Light-Emitting Diodes with MgF2 as the Anode Buffer Layer

Organic light-emitting diodes （OLEDs） based on N,N＇-bis（1-naphthyl）-N,N＇-diphenyl-1,l1＇-biphenyl-4,4＇-diamine （NPB） and tris （8-hydroxyquinoline） aluminium （Alq3 ） are improved by using a thin MgF2 buffer layer sandwiched between the indium tin oxide （ITO） anode and hole transporting layer （HTL） of NPB. The current-voltage curves of the OLEDs with MgF2 buffers shift to lower voltages, which can be explained by the tunnelling effect. Under 10 V bias, the current density and brightness for the optimized OLED with a 1.0-nm MgF2 are 196A/m^2 and 517cd/m^2, respectively, while for the OLED without anode buffer layer are only 109A/m^2 and 156cd/m^2, The atomic force microscopy shows that the rms roughness of NPB on ITO/MgF2 is only 1/3 of NPB on bare ITO. The improved morphology of the HTL would lead to more robust OLEDs. The OLED with a 1.0-nm MgF2 layer has a long lifetime of more than five times of the MgF2-free reference device due to the combined electrical and morphological effects of the MgF2 layer.

A hybrid model for the charging process of the amorphous SiO_2 film in radio frequency microelectromechanical system capacitive switches

Charging is one of the most important reliability issues in radio frequency microelectro- mechanical systems （RF MEMS） capacitive switches since it makes the actuation voltage unstable. This paper proposes a hybrid model to describe the transient dielectric charging and discharging process in the defect-rich amorphous SiO2 RF MEMS capacitive switches and verifies experimentally. The hybrid model contains two parts according to two different charging mechanisms of the amorphous SiO2, which are the polarisation and charge injection. The models for polarisation and for charge injection are established, respectively. Analysis and experimental results show that polarisation is always effective, while the charge injection has a threshold electric field to the amorphous SiO2 film. Under different control voltage conditions, the hybrid model can accurately describe the experimental data.

Enhanced photoresponse of Ti0_(2)/MoS_(2)heterostructure phototransistors by the coupling of interface charge transfer and photogating

Two-dimensional(2D)MoS_(2)with appealing physical properties is a promising candidate for next-generation electronic and optoelectronic devices,where the ultrathin MoS_(2)is usually laid on or gated by a dielectric oxide layer.The oxide/MoS_(2)interfaces widely existing in these devices have significant impacts on the carrier transport of the MoS_(2)channel by diverse interface interactions.Artificial design of the oxide/MoS_(2)interfaces would provide an effective way to break through the performance limit of the 2D devices but has yet been well explored.Here,we report a high-performance MoS_(2)-based phototransistor with an enhanced photoresponse by interfacing few-layer MoS_(2)with an ultrathin Ti0_(2)layer.The Ti0_(2)is deposited on MoS_(2)through the oxidation of an e-beam-evaporated ultrathin Ti layer.Upon a visible-light illumination,the fabricated Ti0_(2)/MoS_(2)phototransistor exhibits a responsivity of up to 2,199 A/W at a gate voltage of 60 V and a detectivity of up to 1.67×10^(13)Jones at a zero-gate voltage under a power density of 23.2μW/mm^(2).These values are 4.0 and 4.2 times those of the pure MoS_(2)phototransistor.The significantly enhanced photoresponse of Ti0_(2)/MoS_(2)device can be attributed to both interface charge transfer and photogating effects.Our results not only provide valuable insights into the interactions at Ti0_(2)/MoS_(2)interface,but also may inspire new approach to develop other novel optoelectronic devices based on 2D layered materials.

Understanding DC Partial Discharge:Recent Progress,Challenges,and Outlooks

As a non-destructive local gas breakdown phenomenon within a surface or bulk cavity surrounded by insulation,partial discharge(PD)contains important information which can be used to evaluate and diagnose electrical insulation systems.In this paper,distinctive characteristics of PD for DC versus AC are reviewed.A summary of experimental studies on DC PD in different insulation coordinations is presented,including PD in gaseous insulating media,PD in solid insulating media and PD in liquid insulating media.Conclusions and some thoughts based on existing studies are provided,and challenges and suggestions for future studies are given.This paper can serve as a guide reference for readers to learn the background and state-of-the-art of DC PD studies.More importantly,it is hopeful that this study can inspire novel ideas for further advancing fundamental research of DC PD mechanisms and PD mitigation methods.

Physics of electron emission and injection in two-dimensional materials: Theory and simulation

Electrically contacting two-dimensional(2D)materials is an inevitable process in the fabrication of devices for both the study of fundamental nanoscale charge transport physics and the design of high-performance novel electronic and optoelectronic devices.The physics of electrical contact formation and interfacial charge injection critically underlies the performance,energyefficiency and the functionality of 2D-material-based devices,thus representing one of the key factors in determining whether 2D materials can be successfully implemented as a new material basis for the development of nextgeneration beyond-silicon solid-state device technology.In this review,the recent developments in the theory and the computational simulation of electron emission,interfacial charge injection and electrical contact formation in 2D material interfaces,heterostructures,and devices are reviewed.Focusing on thermionic charge injection phenomena which are omnipresent in 2Dmaterials-based metal/semiconductor Schottky contacts,we summarize various transport models and scaling laws recently developed for 2D materials.Recent progress on the first-principle density functional theory simulation of 2D-material-based electrical contacts are also reviewed.This review aims to provide a crystalized summary on the physics of charge injection in the 2D Flatlands for bridging the theoretical and the experimental research communities of 2D material device physics and technology.

A 10-bit 100-Msps low power time-interleaved ADC using OTA sharing

A high performance 10-bit 100-MS/s two-channel time-interleaved pipelined ADC is designed for intermediate frequency 3G receivers,and OTA is shared among the channels for low power dissipation.Offset mismatch, gain mismatch and time skew mismatch are overcome by OTA sharing,increasing the accuracy of each channel and global passive sampling respectively.The linearity deterioration caused by the charge injection of the output switch and the crosstalk of the off-switch capacitor is removed by modifying the clock signal arrangement.The total power consumption of the presented ADC is 70 mW from a 3.3-V power supply.Fabricated in a 180-nm CMOS process,the core of the prototype occupies an area of 2.5×1.5 mm;,achieving more than 70-dB spurious-free dynamic range and over 56-dB signal-to-noise distortion ratio over the Nyquist input band at 100-MHz sampling frequency.

ZnO Surface Passivation with Glucose Enables Simultaneously Improving Efficiency and Stability of Inverted Polymer:Non-fullerene Solar Cells

The power conversion efficiency(PCE)of polymer solar cells(PSCs)has exceeded 19%due to the rapid progress of photoactive organic materials,including conjugated polymer donors and the matched non-fullerene acceptors(NFAs).Due to the high density of oxygen vacancies and the consequent photocatalytic reactivity of ZnO,structure inverted polymer solar cells with the ZnO electron transport layer(ETL)usually suffer poor device photostability.In this work,the eco-friendly glucose(Glu)is found to simultaneously improve the efficiency and stability of polymer:NFA solar cells.Under the optimal conditions,we achieved improved PCEs from 14.77%to 15.86%for the PM6:Y6 solar cells.Such a PCE improvement was attributed to the improvement in J_(SC) and FF,which is ascribed to the smoother and more hydrophobic surface of the ZnO/Glu surface,thereby enhancing the charge extraction efficiency and inhibiting charge recombination.Besides,UV-Vis absorption spectra analysis revealed that glucose modification could significantly inhibit the photodegradation of Y6,resulting in a significant improvement in the stability of the device with 92%of its initial PCE after aging for 1250 h.The application of natural interface materials in this work brings hope for the commercial application of organic solar cells and provides new ideas for developing new interface materials.

A novel 2.2 Gbps LVDS driver circuit design based on 0.35μm CMOS

This paper presents a novel high-speed low voltage differential signaling （LVDS） driver design for pointto-point communication. The switching noise of the driver was greatly suppressed by adding a charge/discharge circuit and the operating frequency of the circuit was also increased. A simple and effective common-mode feedback circuit was added to stabilize the output common-mode voltage. The proposed driver was implemented in a standard 0.35 μm CMOS process with a die area of 0.15 mm^2. The test result shows that the proposed driver works well at 2.2 Gbps with power consumption of only 23 mW and 21.35 ps peak-to-peak jitter under a 1.8 V power supply.

In-Vitro and In-Vivo Electrical Characteristics of a Penetrating Microelectrode Array for Optic Nerve Electrical Stimulation

The Chinese C-Sight team aims to restore vision to blind patients by means of stimulating the optic nerve with a penetrating microelectrode array. A biocompatible, implantable microwire array was developed having four platinum-iridium shafts, each 100μm in diameter. This penetrating microwire array is described in this paper, including its fabrication techniques and its in-vitro electrical characteristics. Every set of four shafts was spaced 0.4mm from center to center, comprising two short shafts that were 0.3mm long and two that were 0.9mm long. This design was intended to stimulate ganglion cell axons at different depths within the optic nerve. In-vitro electrochemical impedance testing results showed that the impedance at 1kHz ranged from 8 to 10kΩ at room temperature. The voltage responses of the arrays to current pulse stimulation indicated a charge-injection capacity of 210μC/cm2. Finally, in-vivo acute animal experiments showed that the amplitude of the electrically evoked potentials (EEPs) measured in primary visual cortex could be as large as 100 μV upon direct stimulation of the optic nerve.