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Spontaneous Charge Generation in Flowing Albumin Solutions at 35 °C and 38 °C
摘要： The time dependence of a charge accumulation in a 10?15 M albumin solution, flowing through a measuring cell of an analytical flow system injector, had a nonlinear character under certain conditions, within a human physiological temperature range. Sharp charge increases depended on albumin concentration. This effect must be taken into consideration when generating models that describe electrokinetic phenomena in flowing protein solutions and when developing analytical flow systems for the registration of biomolecules in low concentration ranges.
关键词： flowing protein solution,charge accumulation,analytical flow-through systems,physiological temperature,serum albumin
更新于2025-09-23 15:22:29
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Photoregeneration of Biomimetic Nicotinamide Adenine Dinucleotide Analogues via a Dye-Sensitized Approach
摘要： Two-step photochemical reduction of an acridinium-based cation 2O+ to the corresponding anion 2O? was investigated using a dye-sensitized approach involving 2O+?COOH attached to the surface of a wide-bandgap semiconductor, p-NiO. The cation 2O+ and corresponding one-electron reduced radical form, 2O? were synthesized and characterized using steady-state UV/vis and electron paramagnectic resonance spectroscopy. The thermodynamics for the photoinduced hole injection from 2O+ and 2O? were evaluated and found to be favorable. Subsequent femtosecond transient absorption spectroscopy was utilized to evaluate the photoinduced hole injection into NiO, starting from 2O+?COOH/NiO and 2O??COOH/NiO samples. The excitation of 2O+?COOH at 620 nm initiated fast (2.8 ps) hole injection into NiO. However, 90% of the charge-separated population recombined within ～40 ps, while ～10% of the charge-separated population exhibited lifetimes longer than the time scale of our instrument (1.6 ns). In the case of 2O??COOH/NiO, the light absorption occurs predominantly by NiO (2O??COOH absorbs at 310 nm) and is associated with the electron transfer from the conduction band of NiO to the radical. The charge-separated state in this case appears to be long-lived, based on the slow (ns) growth of the trapped carriers formed on the NiO surface. The results of this work indicate that the photochemical reduction of 2O+ to the corresponding hydride form (2OH) can be achieved, opening the possibility of using such a dye-sensitized approach for regeneration of nicotinamide adenine dinucleotide analogues in enzymatic and chemical catalysis.
关键词： multiple charge accumulation,stable radical,NADH,photochemistry,NiO,dye sensitization
更新于2025-09-23 15:21:21
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Charge Accumulation, Recombination, and Their Associated Time Scale in Efficient (GUA) <i> <sub/>x</sub></i> (MA) <sub/> 1– <i>x</i> </sub> PbI <sub/>3</sub> -Based Perovskite Solar Cells
摘要： Here, we study the influence of guanidinium (GUA) ions on the open-circuit voltage (Voc) in the (GUA)x(MA)1?xPbI3 based perovskite solar cells. We demonstrate that incorporation of GUA forms electronic and ionic accumulation regions at the interface of the electron transporting layer and perovskite absorber layer. Our electrochemical impedance spectroscopy results prove that the formed accumulation region is associated with the enhanced surface charge capacitance and photovoltage. Furthermore, we also demonstrate the influence of the GUA ions on the enhanced interfacial and bulk electronic properties due to more efficient charge transfer between the bulk and interfaces and the reduced electronic defect energy levels.
关键词： perovskite solar cells,guanidinium,recombination,open-circuit voltage,charge accumulation
更新于2025-09-16 10:30:52
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Illustrating the Shell Thickness Dependence in Alloyed Core/Shell Quantum Dot based Light-Emitting Diodes by Impedance Spectroscopy
摘要： Colloidal quantum dots (QDs) are talented materials and have been extensively investigated in the field of photonics and optoelectronics due to their size-dependent optical properties. The core/shell structure of QDs with wide bandgap shell has been adopted for obtaining stable emission and high PL quantum efficiency. However, when employed in active devices such as light-emitting diodes (LEDs), the thick shell structure of QDs may impede the transportation of carriers thus deteriorate the device performance. In this work, the effect of shell thickness of CdSe/ZnS QDs on device performance is systematically studied through impedance spectroscopy (IS) by constructing the electron-only symmetric device architecture. It is found that the evolution of capacitance in the symmetric device under applied voltage reflects the charge accumulation within the device and predicts the LED performance. The lowest capacitance is evaluated in the symmetric device containing QDs with a medium shell size of 2.1 nm, showing improved performance in LED with the highest luminance and current efficiency (CE) of 26370 cd/m2 and 8.3 cd/A respectively.
关键词： impedance spectroscopy,light-emitting diodes,charge accumulation,shell thickness,Colloidal quantum dots
更新于2025-09-16 10:30:52
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Exploring Electronic and Excitonic Processes Towards Efficient Deep Red CuInS2/ZnS Quantum-dot Light-emitting Diodes
摘要： The electroluminescence mechanisms in the Cd-free CuInS2/ZnS quantum-dot based light-emitting diodes (QLEDs) are systematically investigated through transient electroluminescence measurements. The results demonstrate that the characteristics of hole transporting layers (HTLs) determine the QLEDs to be activated by the direct charge-injection or the energy-transfer. Moreover, both the energy level alignment between HTL and quantum dot and the carrier mobility properties of the HTLs are critical factors to affect the device performance. By choosing suitable HTL, such as 4,4'-bis(9-carbazolyl)-2,2'-biphenyl, highly efficient deep red (emission peak at ~650 nm) CuInS2/ZnS QLEDs based on single HTL can be obtained with peak current efficiency and luminance of ~2.0 cd/A and nearby 3000 cd/m2, respectively.
关键词： energy transfer,charge injection,hole-transport layer,QLEDs,electron leakage,charge accumulation
更新于2025-09-11 14:15:04
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Universal explanation for degradation by charge accumulation in crystalline Si photovoltaic modules with application of high voltage
摘要： It was experimentally found that surface recombination due to charge accumulation, called polarization-type potential-induced degradation (PID), occurs by applying high voltage in n-type crystalline Si photovoltaic (PV) modules. By contrast, polarization-type PID has not been observed yet in p-type crystalline Si PV modules. We investigated the effect of differences in anti-reflection coating (ARC) and the conduction type of the substrate used as a base for PV cells on PID. PID was examined for PV modules using p-type and n-type crystalline Si PV cells with a SiNx or SiNx/SiO2 stacked ARC layer. The results indicate that PID owing to charge accumulation occurs even for p-type crystalline Si PV modules by applying high positive voltage. Furthermore, we found that polarization-type PID due to charge accumulation in ARC, leading to surface recombination, is due not to the conduction type of the substrate but to the ARC structure.
关键词： potential-induced degradation,anti-reflection coating,surface recombination,charge accumulation,photovoltaic modules
更新于2025-09-11 14:15:04
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Numerical simulation on the surface charge accumulation process of epoxy insulator under needle-plane corona discharge in air
摘要： Most of the HV power equipment with gas–solid insulation suffers a lot from the surface charge accumulation due to corona discharge. The existence of surface charge distorts the local electric field and leads to surface flashover faults in extreme situations. As a result, it is important to figure out the mechanism of surface charge accumulation process. In this study, a simulation model combining both the plasma hydrodynamics and charge trapping–detrapping process was built. The simulation results have a good agreement with the experimental data, the main summary is as follows: in the surface charge accumulation process, the corona discharge intensity increases first and then decreases with time. The curves of the surface potential distributions have different shapes at different times, the central value goes up rapidly with time in the beginning and finally reaches saturation. Surface charges exist in the skin layer of epoxy insulator, some of them may be captured by traps while transporting away under built-in electric field.
关键词： corona discharge,charge trapping–detrapping process,plasma hydrodynamics,epoxy insulator,surface charge accumulation
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Influence of temperature gradient on charge accumulation phenomena of GIS spacer under DC field
摘要： DC-GIS is used in HVDC systems because of its excellent insulation performance. However, when DC voltage is applied to DC-GIS, charges are accumulated on the surface of the insulator. This leads to decrease the breakdown voltage. Therefore, understanding charge accumulation phenomena is significant to make more reliable HVDC systems. In this paper, we focused on effects of the temperature gradient on the spacer to charge accumulation phenomena. We developed the experimental device which makes thermal distribution on an insulated model spacer and we measured charge distributions on it under temperature gradient. Also, numerical simulation was conducted to understand this phenomenon. We concluded that when temperature gradient is generated in the spacer, charging is more widely distributed.
关键词： temperature gradient,charge accumulation,GIS,spacer
更新于2025-09-10 09:29:36
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Influence of charge accumulation at the grain boundary on the electrical behavior of a ferroelectric field-effect transistor
摘要： A phase field method was used to investigate the influence of charge accumulation at the grain boundary on the electrical behavior of a ferroelectric field-effect transistor containing a polycrystalline gate. Both the domain structure and the electrical behavior of the ferroelectric field-effect transistor were found to depend on the coefficient χ, which represents the charge accumulation at the grain boundary. With increasing χ, both the width of the memory window of the capacitance–voltage curves and the on-state source–drain current decreased, while the off-state source–drain current increased. This can be explained in terms of the weakening polarization effect in the grain interior owing to the presence of a built-in electric field caused by the accumulated charge at the grain boundary.
关键词： electrical behavior,charge accumulation,phase field method,grain boundary,ferroelectric field-effect transistor
更新于2025-09-09 09:28:46
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A monitoring device made of an anodic aluminum oxide template for plasma-induced charging potential measurements in the high-aspect-ratio trench structure
摘要： A monitoring device is proposed to investigate the charge accumulation effects in a high-aspect-ratio trench structure. This monitoring device is made of an anodic aluminum oxide (AAO) template, which is a self-organized material with parallel pores, to demonstrate a high aspect ratio trench structure. A top electrode and bottom electrode were formed in the AAO contact structure for measuring electric potentials. These electrodes can be assumed to be electrically floating due to the very high input resistance of the measurement circuit. Therefore, the electric potentials resulting from the charge accumulation can be measured. In this paper, the fabrication process of the proposed device and experimental demonstrations are presented.
关键词： high-aspect-ratio trench structure,charge accumulation,monitoring device,anodic aluminum oxide,plasma-induced charging potential
更新于2025-09-09 09:28:46