Charge Transport Behavior Research Articles

A Versatile Photoelectrochemical System with Feooh/MoOx/BiVO4 for Reactive Halogen Species Generation Coupled with Hydrogen Evolution

Solar-driven seawater splitting is a promising approach for sustainable green hydrogen generation. Chlorine evolution reaction (ClER) can provide much faster kinetics than oxygen evolution reaction (OER), due to lower number of electrons involved in the interfacial charge transfer. Designing stable and efficient photoelectrodes for a photoelectrochemical (PEC) seawater splitting presents challenges due to the corrosive nature of seawater. BiVO4 has been a promising photoanode for solar energy conversion to molecular hydrogen (H2), due to desirable bandgap (2.4 eV), favorable band position and chemical stability. Nevertheless, BiVO4 has been mostly employed for OER, and shows limitation of poor charge transport and insufficient active sites for interfacial charge transfer. This study proposed a composite photoanode comprising MoOx hole transfer layer and iron oxyhydroxide (FeOOH) electrocatalysts on BiVO4, to enhance photocurrent and stability in the PEC seawater splitting. The MoOx layer, containing Mo6+ as electron donors, was deposited on BiVO4 using a simple drop-casting method. A simple reductive electrodeposition introduced the FeOOH electrocatalysts, while simultaneously forming MoOx with surface defect states (FeOOH/MoOx/BiVO4) to facilitate the facilitating hole transfer through the segregated MoOx layer. The surface structure of FeOOH/MoOx/BiVO4 photoanode was investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) confirmed successful synthesis of MoOx and FeOOH layers on BiVO4. The charge separation efficiency was four times higher on the FeOOH/MoOx/BiVO4 photoanode (78%) compared to the intact BiVO4 photoanode (18%). Additionally, the FeOOH/MoOx/BiVO4 photoanode exhibited improved photocurrent density for OER and ClER under simulated AM 1.5 G sunlight, reaching 3.3 mA cm-2 at 1.23 VRHE in circum-neutral pH, which is approximately three times higher than that of the intact BiVO4. The applied bias photon-to-current efficiency (ABPE) of the FeOOH/MoOx/BiVO4 photoanode reached 0.9% at 1.23 VRHE, five times higher than that of intact BiVO4. Such excellent PEC activity can be ascribed to introduced surface defects (such as oxygen vacancy) on MoOx/BiVO4 and alleviated kinetic barrier by FeOOH. Moreover, the photocurrent density of the FeOOH/MoOx/BiVO4 photoanode in a 0.5 M NaCl electrolyte (for ClER) was 0.5 mA cm-2 higher than that in 0.5 M Na2SO4 electrolyte (for OER). Transient absorption spectroscopy (TAS) confirmed the improved charge transport behavior of the modified BiVO4 for OER or ClER. The generation of reactive chlorine species could compromise the stability of FeOOH, which could be mitigated by an added aqueous pollutants. For instance, in the PEC chlorine evolution reaction system, ammonia or 4-chlorophenol as model pollutant enhanced the stability. Notably, the FeOOH/MoOx/BiVO4 exhibited a 10-fold higher rate for ammonia oxidation compared to the intact BiVO4. A moderated concentration of bromide ion could further elevate the photocurrent density. The increased photocurrent activity of the modified FeOOH/MoOx/BiVO4 photoanode in PEC splitting of blended seawater and wastewater can serve multifaceted purposes, enhancing the efficiency of pollutants degradation (or chemical upgrading) and H2 evolution.

Self-Powered Broadband Photodetection Ranging from X-ray to UV-Vis Light in a Polar Perovskite Induced by Bulk Photovoltaic Effect.

Self-powered broadband photodetection has evoked increased interest in next-generation photoelectronic devices. However, realizing self-powered broadband photodetection in a single material is still a challenge because of the harsh requirements, including powerful built-in field, excellent charge transport behaviors, as well as the broad absorption. Herein, we first realize broadband photodetection in the range from X-ray to UV-vis light in a polar two-dimensional perovskite (2-FBA)2MAPb2I7 (2-FBA = 2-fluorobenzylamine, MA = methylamine) by incorporating an aromatic spacer into a three-dimensional prototype. As a result, (2-FBA)2MAPb2I7 exhibited a superior response to UV-vis light (377 to 637 nm) without voltage bias. Specifically, a high switching ratio of 1.05 × 104, an outstanding responsivity (R) of 1420 mA W-1, and detectivity (D*) of 1.59 × 1013 Jones were achieved under light illumination at 520 nm. Moreover, (2-FBA)2MAPb2I7 achieved a high sensitivity of 46.4 μC Gy-1 cm-2 without voltage bias, two times higher than that of a commercial α-Se film detector (20 μC Gy-1 cm-2). The sensitivity can be further improved to 3316 μC Gy-1 cm-2 at a 50 V bias. These results give insight into the design of 2D perovskites for self-powered broadband photodetection.

Evolution laws of charge mobility of transformer oil and pressboard material with temperature and electric field strength

Abstract Charge mobility, a pivotal parameter in the space charge analysis model for oil-pressboard insulation of converter transformer under DC electric fields, predominantly relies on theoretical or empirical data. The prevalent omission of empirical, measurement-based evaluations, combined with the neglect of temperature and electric field intensity effects, introduces uncertainties in the calculation of electric field and charge dynamics. Grounded on the principles of the electroacoustic pulse technique for space charge measurements, our investigation established a temperature-controlled platform to determine the charge-charge mobility in oil and pressboard insulation mediums. Utilizing diverse oil-pressboard insulation systems, this study identified the temporal patterns of both positive and negative charge mobilities and unravelled the mechanisms modulated by temperature and electric field intensity: (1) with increasing temperatures (from 20 °C to 80 °C) and intensifying electric field strengths (from 5kV mm−1 to 25kV mm−1), the charge mobility within transformer oil and pressboard exhibits a rising trend. Notably, temperature variations exert the most significant influence, yielding amplifications up to 24.8 times. (2) The intrinsic properties of different transformer oils and oil-impregnated pressboards result in pronounced differences in their charge transport behaviors. Specifically, naphthenic-based oil demonstrates enhanced charge mobility relative to its paraffin-based counterpart. In contrast, transformer oils with higher kinematic viscosities exhibit diminished charge mobility compared to those with lower viscosities. (3) A linear relationship is observed between the oil absorption rate and electrical conductivity, aligning closely with the insulating pressboard’s charge mobility. The evaluation of electric field and interface charge dynamics in oil-pressboard insulation under both DC and polarity-reversed conditions revealed that the electric field decay in naphthenic-based oil is more rapid than in paraffin-based oils. Moreover, both the magnitude and rate of interface charge accumulation in naphthenic-based oils exceed those in paraffin-based variants, further validating the accuracy of our charge mobility measurements and ensuing analysis.

Tetrazaisoindigos:Serpentine Syntheses and Their Expected and Unexpected Photophysical and Electronic Properties.

Isoindigo, an electron-withdrawing building block for polymeric field-effect transistors, has long been considered to be non-fluorescent. Moreover, using electron-deficient heterocycle to replace the phenyl ring in the isoindigo core for better electron transport behaviour is synthetically challenging. Here we report the syntheses of a series of tetrazaisoindigos, including pyrazinoisoindigo (PyrII), pyrimidoisoindigo (PymII) and their hybrid (PyrPymII), and the investigation on their photophysical and electric properties. Proper flanking groups need to be chosen to stabilize these highly electron-deficient bislactams. Both PyrII and PymII derivatives show lower LUMO energy levels than that of naphthalene bisimide (NDI). Interestingly, PyrII is instinctively unstable and can be easily reduced, while both PymII derivatives are stable. More surprisingly, PymII derivatives are highly fluorescent and their photoluminescence quantum yields are around 40 %, 133 times higher than that of reported isoindigo derivatives. UV-vis spectroscopic results and theoretical calculations show that strong intramolecular hydrogen-bond exists in PymII, which prohibits it from non-radiative decay and accounts for its fluorescent behaviour. PymII derivatives are n-type semiconductors, while Ph-PyrII and the hybrid show balanced ambipolar charge transport behaviour, all among the best isoindigo derivatives. Our study not only discloses the structure-property relationship of tetrazaisoindigos, but also provides novel electron-deficient monomers for conjugated polymers.

A semiconducting supramolecular Co(II)-metallogel based resistive random access memory (RRAM) design with good endurance capabilities.

A highly efficient approach for synthesizing a supramolecular metallogel of Co(II) ions, denoted as CoA-TA, has been established under room temperature and atmospheric pressure conditions. This method employs the metal-coordinating organic ligand benzene-1,3,5-tricarboxylic acid as a low molecular weight gelator (LMWG) in DMF solvent. A comprehensive analysis of the mechanical properties of the resulting supramolecular Co(II)-metallogel was conducted through rheological investigation, considering angular frequency and thixotropic study. The hierarchical rocky network structure of the supramolecular Co(II)-metallogel was unveiled using field emission scanning electron microscopy (FESEM). Transmission electron microscopic (TEM) analysis showed rod-shaped structures via low-magnification high angle annular dark field (HAADF) bright field scanning transmission electron microscopic (STEM) imaging, while energy dispersive X-ray (EDX) elemental mapping confirmed its primary chemical constituents. The formation mechanism of the metallogel was examined via fourier transform infrared spectroscopy (FTIR) spectroscopy. The nature of the synthesized CoA-TA metallogel was affirmed through powder X-ray diffraction (PXRD) analysis. Furthermore, this study involved fabrication of Schottky diode structures in a metal-semiconductor-metal geometry based on cobalt(II) metallogel (CoA-TA), enabling observation of charge transport behavior. Remarkably, a resistive random access memory (RRAM) device utilizing cobalt(II) metallohydrogel (CoA-TA) demonstrated bipolar resistive switching at room temperature and under ambient conditions. The switching mechanism was investigated, revealing the formation and rupture of conductive filaments between metal electrodes that govern the resistive switching behavior. This RRAM device exhibited an impressive ON/OFF ratio (~ 414) and exceptional endurance over 5000 switching cycles. These structures offer great potential for diverse applications such as non-volatile memory design, neuromorphic computing, flexible electronics and optoelectronics. Their advantages lie in their fabrication process, reliable resistive switching behavior and overall performance stability.

Polymer semiconductor films and bacteria hybrid artificial bio-leaves.

Bio-artificial photosynthetic systems can reduce CO2 into multicarbon compounds by simulating natural photosynthesis. Here, inspired by organic photovoltaic structures, we demonstrate a bio-artificial photosynthetic system based on the hybridization of polymer semiconductor films and bacteria. The study suggests that the polymer-based semiconductor film can efficiently drive the non-photosynthetic bacteria to convert CO2 to acetate. By systematically characterizing the charge transport behavior of the bio-artificial photosynthetic system, the bulk-heterojunction structure and charge transport layers are proven to enhance the system performance markedly. The scalable floating artificial bio-leaf system can produce acetate to gram scale in a week. Notably, the semiconductor film is easy to recycle and maintains stable performance, showing good sustainable production capability of the system. A quasi-solid-state artificial bio-leaf is successfully prepared using agar to simulate the morphology and function of natural leaves. Last, the acetate production converted from CO2 was used to grow yeast for food production, thus achieving a complete simulation of natural photosynthesis.

Probing Nanoscale Charge Transport Mechanisms in Quasi-2D Halide Perovskites for Photovoltaic Applications.

Quasi-2D layered halide perovskites (quasi-2DLPs) have emerged as promising materials for photovoltaic (PV) applications owing to their advantageous bandgap for absorbing visible light and the improved stability they enable. Their charge transport mechanism is heavily influenced by the grain orientation of their crystals as well as their nanostructures, such as grain boundaries (GBs) and edge states─the formation of which is inevitable in polycrystalline quasi-2DLP thin films. Despite their importance, the impact of these features on charge transport remains unexplored. In this study, we conduct a detailed investigation on polycrystalline quasi-2DLP thin films and devices, carefully analyzing how grain orientation and nanostructures influence charge transport. Employing nondestructive atomic force microscopy (AFM) topography, along with transient absorption spectroscopy (TAS) and grazing-incidence wide-angle X-ray scattering (GIWAXS), we obtained significant insights regarding the phase purity, crystallographic information, and morphologies of these films. Moreover, our systematic investigation using AFM-based techniques, including Kelvin probe force microscopy (KPFM) and conductive AFM (c-AFM), elucidates the roles played by GBs and edge states in shaping charge transport behavior. In particular, the local band structure along the GBs and edge states within both vertical and parallel grains was found to selectively repel electrons and holes, thus facilitating charge carrier separation. These findings provide perspectives for the development of high-performance quasi-2DLP PV devices and highlight potential approaches that can leverage the intrinsic properties of quasi-2DLPs to advance the performance of perovskite solar cells.

Effect of Temperature and Electric Field Strength on Carrier Mobility of Oil-Impregnated Pressboard Under DC Voltage

The influence of carrier mobility on the space charge transport behavior inside the oil-impregnated pressboard insulation of converter transformers cannot be neglected. However, at present, current knowledge is usually derived from empirical or theoretical values, lacks experimental studies, and often ignores the effects of temperature and field strength under actual operating conditions. In this paper, based on the variable-temperature surface potential decay (SPD) method, a carrier mobility measurement platform for oil-impregnated pressboard is established, and the carrier mobility values for different combinations of oil and oil-impregnated pressboard are obtained experimentally to analyze and reveal the influence mechanisms of temperature and field strength on the carrier mobility. The results indicate the following: (1) The positive and negative carrier mobilities of oil-impregnated pressboard are in the range of 10−12–10−13 m2·V−1·s−1, and the negative carrier mobility is always higher than the positive carrier mobility. (2) The carrier mobility is positively correlated with the changes of temperature and field strength, and when the temperature increases from 20 °C to 80 °C, the positive and negative carrier mobilities increase by 4.01 times and 4.72 times, respectively; when the field strength increases from 1 kV/mm to 7 kV/mm, the positive and negative carrier mobility increases by 2.53 and 2.72 times, respectively. (3) The carrier mobility of the pressboard with a higher oil absorption rate changes more significantly with temperature; when the field strength is 7 kV/mm and the temperature increases from 20 °C to 80 °C, the positive polarity carrier mobility increases from 3.96 × 10−13 m2·V−1·s−1 to 2.64 × 10−11 m2·V−1·s−1, an increase of 66.67 times, while the increase in the carrier mobility of the pressboard with a lower oil absorption rate is only 1.59 times. (4) The carrier mobility of the naphthenic transformer oil-impregnated pressboard is higher than that of the paraffin-based transformer oil-impregnated pressboard, and the carrier mobility of two kinds of naphthenic transformer oil-impregnated pressboard is 3.16 times and 2.47 times higher than that of the paraffin-based transformer oil-impregnated pressboard, respectively, under the conditions of 60 °C and 7 kV/mm. (5) Utilizing the Darcy model and microscopic scanning results of the pressboard morphology, it was revealed that permeability and fiber structure are key factors influencing the variation in carrier mobility. The research results of this paper can provide theoretical basis for the calibration and optimization of the oil-pressboard insulation structure of converter transformers.

Towards Stable Helical Structures with Enhanced Molecular Conductance by Strengthening Through‐Space Conjugation

AbstractDeveloping long‐chain molecules with stable helical structures is of significant importance for understanding and modulating the properties and functions of helical biological macromolecules, but challenging. In this work, an effective and facile approach to stabilize folded helical structures by strengthening through‐space conjugation is proposed, using new ortho‐hexaphenylene (o‐HP) derivatives as models. The structure–activity relationship between the through‐space conjugation and charge‐transport behavior of the prepared folded helical o‐HP derivatives is experimentally and theoretically investigated. It is demonstrated that the through‐space conjugation within o‐HP derivatives can be strengthened by introducing electron‐withdrawing pyridine and pyrazine rings, which can effectively stabilize the helical structures of o‐HP derivatives. Moreover, scanning tunneling microscopy‐break junction measurements reveal that the stable regular helical structures of o‐HP derivatives open‐up dominant through‐space charge‐transport pathways, and the single‐molecule conductance is enhanced by more than 70 % by strengthening through‐space conjugation with pyridine and pyrazine. However, the through‐bond charge transport pathways contribute much less to the conductance of o‐HP derivatives. These results not only provide a new method for exploring stable helical molecules, but also provide a stepping stone for deciphering and modulating the charge‐transport behavior of helical systems at the single‐molecule level.

Towards Stable Helical Structures with Enhanced Molecular Conductance by Strengthening Through-Space Conjugation.

Developing long-chain molecules with stable helical structures is of significant importance for understanding and modulating the properties and functions of helical biological macromolecules, but challenging. In this work, an effective and facile approach to stabilize folded helical structures by strengthening through-space conjugation is proposed, using new ortho-hexaphenylene (o-HP) derivatives as models. The structure-activity relationship between the through-space conjugation and charge-transport behavior of the prepared folded helical o-HP derivatives is experimentally and theoretically investigated. It is demonstrated that the through-space conjugation within o-HP derivatives can be strengthened by introducing electron-withdrawing pyridine and pyrazine rings, which can effectively stabilize the helical structures of o-HP derivatives. Moreover, scanning tunneling microscopy-break junction measurements reveal that the stable regular helical structures of o-HP derivatives open-up dominant through-space charge-transport pathways, and the single-molecule conductance is enhanced by more than 70 % by strengthening through-space conjugation with pyridine and pyrazine. However, the through-bond charge transport pathways contribute much less to the conductance of o-HP derivatives. These results not only provide a new method for exploring stable helical molecules, but also provide a stepping stone for deciphering and modulating the charge-transport behavior of helical systems at the single-molecule level.

Photocarrier behavior and photocatalytic H2O2 synthesis performance of amorphous/crystalline SrTiO3/BiVO4 layered heterostructures

BiVO4 (BVO), as a visible light responsive semiconductor material, has been widely employed in the field of photocatalysis. However, monoclinic BVO is afflicted by a high recombination rate of photogenerated charge carriers and poor charge transport capability, resulting in low charge utilization efficiency. Constructing heterostructures for interface modification of BVO is an effective strategy to improve photocatalytic performance. Herein, amorphous/crystalline SrTiO3/BiVO4 (STO/BVO) layered film nanoheterostructures have been successfully fabricated on the (001) yttrium stabilized zirconia substrate by magnetron sputtering. Under 440 nm monochromatic light irradiation, the H2O2 production rate of the composite film is increased by 1.2 times compared to pure BVO. The type II heterostructure composed of STO and BVO accomplishes selective interface hole transport from BVO to STO, promoting the separation of space charges. Additionally, the interaction between amorphous/crystalline interfaces effectively suppresses the photocorrosion of BVO and strengthens the stability of the film, which is of great significance for studying charge transport behavior and photocatalytic mechanisms.

Improving the photoswitching performance of a transistor with amorphous metal oxide semiconductor thin film by a gradient annealing approach

Metal oxides are attracting attention as electronic mate rials in research and industry. Thin films of amorphous indium gallium zinc oxide (a-IGZO) exhibit low absorbance in the visible spectrum, making them ideal components in transparent electronics. To widen the scope of use for thin film transistor (TFT) devices based on a-IGZO in on-chip sensing applications, photoresponsive behavior has been achieved by proper engineering of the active layers by either introducing a photosensitive top layer or using a method to generate localized states inside the band gap. In this paper, we propose a bilayer structured with the use of thermal annealing of a-IGZO film at different temperatures. Thermal annealing has been shown to improve the electrical performance of the TFT devices because of the improved film quality but negatively affects the photoresponsivity by removing tarp sites that play an important role in both charge generation and photomultiplication via the photogating effect. Therefore, here we propose an a-IGZO film with a high temperature-annealed bottom layer and pristine top layer. The bottom layer plays a vital role in the charge transport behavior, resulting in a low threshold voltage and subthreshold swing similar to the device with a fully annealed film, while the photoresponse of the device is driven by the higher density of gap states in the pristine top layer. This proposed method is advantageous to previously published procedures due to the simplicity of using no additional materials and complex steps to introduce trap sites into the photoactive layer, but only differential annealing temperature.

Phase Distribution Dictates Charge Transfer and Transport Dynamics in Layered Quasi-2D Perovskite.

Strategic manipulation of spatiotemporal evolution of charge carriers is critical for optimizing performance of quasi-two-dimensional (2D) perovskite-based optoelectronic devices. Nonetheless, the inhomogeneous phase distribution and band alignment engender intricate energy landscapes, complicating internal charge and energy funneling processes. Herein, we integrate high spatiotemporal resolution transient absorption microscopy with multiple time-resolved spectroscopy and find that asynchronous electron and hole transfers rather than direct energy transfer govern the funneling mechanisms. Notably, the charge funneling pathways and transport behaviors can be modifiable by phase manipulation. The accumulation of small-n phases suppresses the electron funneling toward large-n phases and doubles the carrier diffusion rate from 0.085 to 0.20 cm2/s, yielding a 1.5-fold enhancement in diffusion length. Phase order engineering is further corroborated for facilitating charge separation. Our investigation underscores the prospects of manipulating the phase distribution to control internal charge funneling and transport, thereby substantiating the theoretical foundations for optimizing optoelectronic devices.

Mechanistic insights into the charge transportation behavior and enhanced photocatalytic performance of BaTiO3/CdS heterostructure by calculations of first-principles and experiments of tracking charge flow direction

Mechanistic insight into charge transportation behavior of the heterogeneous photocatalyst is a key issue to elucidate the photocatalytic performance. This study aims to employ first-principles calculations and tracking charge flow direction to reveal the charge transportation behavior and enhanced photocatalytic performance of CdS modified tetragonal phase BaTiO3 (BTO/CdS). The experiment of X-ray photoelectron spectroscopy and the first-principles calculations confirm the establishment of a built-in electric field and a type-II energy alignment, which are favorable for transport and separation of charge carriers in BTO/CdS heterojunction. The tracking charge flow direction demonstrates that photogenerated electrons of CdS transfer to BTO and photogenerated holes of BTO transfer to CdS. As a result, the constructed BTO/CdS heterojunction nanostructure exhibits substantially enhanced photocatalytic performance. The degradation rate of rhodamine B by BTO/CdS photocatalyst is 98.6 % under simulated light irradiation within 25 min, which is significantly higher than that (29.0 %) of the pure BTO photocatalyst. This study offers a rational strategy to understand the charge transportation behavior and enhanced photocatalytic performance of heterostructures by first-principles calculations and tracking charge flow direction for the design of high-performance photocatalysts.

Ideal quadratic nodal point in half-Heusler semimetal LaPtBi

The research focus on topological states in electronic systems has recently expanded from traditional linear dispersions to encompass higher-order dispersions. These higher-order dispersions exhibit unique physical properties, including high topological charge, exotic magnetoresponse, and novel transport behaviors. In this study, we employ first-principles calculations to propose the half-Heusler material LaPtBi as an ideal quadratic nodal point semimetal. Our comprehensive analysis of the band structure reveals an ideal nodal point located precisely at the Fermi level, exhibiting quadratic dispersion in all directions. This finding is supported by symmetry analysis and effective model arguments. Moreover, when the spin-orbit coupling effect is considered, the nodal point transitions from triple to quadruple degeneracy, while maintaining its quadratic dispersion. The material also features multiple prominent arc surface states originating from the nodal point, which are distinctly separated from the bulk bands. This separation facilitates experimental verification. Overall, LaPtBi, with its quadratic nodal point and advantageous properties, serves as an ideal platform for further research. The study of this material is expected to enhance our understanding of higher-order topological states in electronic systems, potentially driving future advancements in the field.

Charge-dependent CALPHAD analysis of defect chemistry and carrier concentration for space charge layers

The development of conductive materials plays a crucial role in improving the efficiency of electrochemical processes. In polycrystalline materials, space charge layers (SCLs) adjacent to grain boundaries (GBs) often dictate charge transport behavior. This study explores relaxing the charge neutrality constraint in the CALculation of PHAse Diagrams (CALPHAD) approach as a new method to model the electrical conductivity effects of SCLs. A new charge-dependent defect chemistry analysis is applied to the wustite, magnetite, and hematite phases in the Fe–O binary system. Using pycalphad, charge-dependent results for the molar Gibbs energies, Brouwer diagrams, and charge carrier concentrations were determined for each phase at 1273K within the oxygen partial pressure stability ranges. With a negative charge of 0.16 × 10−19 C, the hematite and magnetite phases exhibit an increased charge carrier concentration. The opposite trend was observed for wustite. While further work is needed to quantify the electrical conductivity effects of the SCLs and GBs with this approach, it provides a robust thermodynamic foundation to rapidly develop and optimize conductive materials.

NiSe2 crystals integrated with nickel cobalt hydroxide for high-performance aqueous supercapacitors

The integration of NiSe2 crystals onto the surface of NiCo-LDHs was successfully achieved by electrostatic self-assembly, thereby enhancing exposure to electrochemical active sites and synergistically improving capacitance performance. First-principles calculations suggest that this integration enhances the proportion of free electrons in NiSe2/NiCo-LDHs, facilitating improved charge transport behavior during electrochemical reactions. As a result of these excellent properties, NiSe2/NiCo-LDHs-4 electrodes exhibit a remarkable specific capacitance of 1252.3 F g−1 at a current density of 1 A g−1 and a capacitance retention of 79.58 % after 4000 cycles at a high current density of 20 A g−1. ASC devices based on NiSe2/NiCo-LDHs-4 exhibit energy densities as high as 36.43 Wh kg−1 at a power density of 1521.73 W kg−1 and capacitance retention as high as 125.88 % after 10,000 cycles at a high current density of 10 A g−1, highlighting the tremendous potential of NiSe2/NiCo-LDHs-4 materials for advanced energy storage applications.

Low-intensity illumination induced relaxation and charge transport behavior of single crystal halide perovskites

Low-intensity illumination induced relaxation and charge transport behavior of single crystal halide perovskites

Electrical properties enhancement of dually grafting modification for polypropylene cable insulation

AbstractPolypropylene (PP) is believed to be a rather promising cable insulating material for high‐capacity electric power system with low carbon emission due to its decent thermo‐resistance and recyclable nature. In this paper, a new dually chemical grafting modification strategy by methyl acrylate (MA) and acrylic acid (AA) is put forward to tailor the charge transportation behavior in PP, thus further enhancing the electrical properties. Experimental results indicate that the dually grafted PP with 2.3 weight percent (wt%) MA and 1.9 wt% AA shows enhanced volume resistivity and electrical breakdown strength than pure PP, and the space charge injection is significantly suppressed. This work further adopts thermally stimulated depolarization current (TSDC) test and computational analysis based on density functional theory (DFT) to reveal the mechanism of enhancement. The analysis shows that grafted chemical groups can introduce quantities of deep traps and electrostatic potential wells which are strongly correlated with the carbonyl group and would hinder the charge transportation thus improving the electrical insulating performances of PP. This work would provide a new route of PP‐based dually grafting modification for the development of high‐voltage cable insulation.

Study on the charge transport behaviour of mxene- polymer nanocomposite-based self-assembled floating films at the air-liquid interface

This study explores the fabrication and charge transport behavior of MXene-polymer nanocomposite-based self-assembled floating films at the air-liquid interface. Utilizing ultrasonic dispersion of MXene nanosheets was integrated into a DPP-TTT polymer matrix, significantly enhancing the alignment and crystallization of the polymer chains. The films were fabricated using a unidirectional floating film transfer method (UFTM), which proved to be both simple and cost-effective. UV–visible and grazing incidence X-ray diffraction (GIXD) analyses confirmed increased π–π stacking and improved structural arrangement within the nanocomposites. Organic field-effect transistors (OFETs) fabricated from these films demonstrated that a 3% MXene inclusion resulted in the highest mobility, measuring 3.1 cm2V-1s-1 with an on-off ratio in the order of 104, compared to 1.3 cm2V-1s-1 in pristine DPP-TTT films. However, further increases in MXene content reduced mobility, emphasizing the importance of precise compositional tuning.