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Pre-orientation stretching of high-density polyethylene improves the charge stability of electrets produced in corona discharge. Electrets made of oriented polyethylene charged in the corona under uniaxial tensile mechanical stress have even greater stability. The increased stability of electrets is due to the capture of electrons in deep structural traps formed after the rupture of macromolecules during orientation and mechanical stress. By the method of thermally stimulated electron emission, it is shown that the charge of electrets is formed at the expense of electrons. New convenient formulas for calculation of electrical voltages in multilayer insulation with electrets were obtained. [ABSTRACT FROM AUTHOR]

We have synthesized L-cysteine and oleylamine stabilized CsPbBr3 perovskite quantum dots (PQDs) and coupled them with gold nanoparticles (AuNPs). The PQDs and AuNPs, as well as their hybrid nanostructures (HNS), were characterized using UV–visible (UV–vis) and photoluminescence (PL) spectroscopy. The UV–vis spectra show absorption bands of the HNS at 503 and 520 nm, attributed mainly to PQDs and AuNPs, respectively. The PQDs show a strong excitonic PL band peaked at 513 nm from PQDs. The HR-TEM results show the formation of hybrid structures between PQDs and AuNPs, which is also supported by the PL quenching of the PQDs by the coupled AuNPs. Ultrafast dynamics of the exciton and charge carriers in the HNS and pristine PQD were studied using femtosecond transient absorption. Multiexponential fitting of the dynamic data revealed the existence of shallow and deep trap states in pristine PQDs and ultrafast electron transfer from PQDs to AuNPs in the HNS. A kinetic model was proposed to account for the key dynamic processes involved and to extract the time for electron transfer from PQDs to AuNPs in the HNS, found to be ∼2 ps. Dynamic processes in pristine PQDs are largely unchanged by HNS formation with AuNPs. [ABSTRACT FROM AUTHOR]

Deep levels in the whole bandgap of 4H-SiC generated by reactive ion etching (RIE) are investigated with both n- and p-type SiC Schottky barrier diodes by deep-level transient spectroscopy (DLTS). Depth profiles of the observed deep levels were analyzed using the DLTS peak intensities at various bias voltages and numerical calculations. The major electron traps detected after RIE and subsequent annealing at 1300 ° C include the Z 1 / 2 (E C − 0.66 eV), ON1 (E C − 0.88 eV), ON2 (E C − 0.95 eV), and EH 6 / 7 (E C − 1.50 eV) centers, and the major hole traps include the UK1 (E V + 0.51 eV), UK2 (E V + 0.72 eV), HK0 (E V + 0.77 eV), HK2 (E V + 0.79 eV), and HK3 (E V + 1.31 eV) centers, where E C and E V denote the conduction and valence band edges, respectively. Most of the traps were localized near the surface (<0.5 μ m) with a maximum density of about 1 × 10 15 cm − 3 , but several traps such as the ON1 and HK0 centers penetrate deep into the bulk region (>2 μ m). By annealing at 1400 ° C, most of the hole traps were eliminated, but several electron traps remained. From these results, the origins of these defects are discussed. [ABSTRACT FROM AUTHOR]

This work aims to validate the feasibility of device-level analysis to reflect the effects of fabrication processes and operations, as contrasted with the conventional method of x-ray photoelectron spectroscopy (XPS), which is widely employed in amorphous oxide semiconductor thin-film transistors (TFTs) but analyzes film-level specimens. First, an analysis setup was introduced to determine the optimal x-ray target position for device-level XPS, where the intensity of channel components is maximized, through imaging XPS. Then, to demonstrate the effectiveness of this approach, the impact of channel composition and bias-stress was investigated through the implementation of device-level XPS on bottom-gate InGaZnO TFTs. The cationic composition ratios of the fabricated TFTs varied from 0.27:1:1.33 (In:Ga:Zn) and 0.28:1:2.21 when the subcycle of the Zn precursor increased by a factor of 1.5 in the atomic-layer deposition process. The device with a higher Zn ratio exhibited a more negative turn-on voltage and a twice larger subthreshold swing. These characteristics were validated from the comparisons in the relative amount of oxygen vacancies in O 1s of the channel and interface regions by 8.4%p and 5.6%p, respectively, between the devices. Furthermore, the electron trapping effect was verified for the devices subjected to a positive gate bias-stress of 3 MV/cm, as evidenced by the changes in the binding energy difference (0.35 eV) between the channel and gate insulator layers, in comparison to the non-stressed device. Consequently, this work demonstrates that device-level XPS can be an effective tool for understanding TFTs' characteristics in various ways beyond film-level analysis. [ABSTRACT FROM AUTHOR]

Granular metals (GMs), consisting of metal nanoparticles separated by an insulating matrix, frequently serve as a platform for fundamental electron transport studies. However, few technologically mature devices incorporating GMs have been realized, in large part because intrinsic defects (e.g., electron trapping sites and metal/insulator interfacial defects) frequently impede electron transport, particularly in GMs that do not contain noble metals. Here, we demonstrate that such defects can be minimized in molybdenum–silicon nitride (Mo–SiNx) GMs via optimization of the sputter deposition atmosphere. For Mo–SiNx GMs deposited in a mixed Ar/N2 environment, x-ray photoemission spectroscopy shows a 40%–60% reduction of interfacial Mo-silicide defects compared to Mo–SiNx GMs sputtered in a pure Ar environment. Electron transport measurements confirm the reduced defect density; the dc conductivity improved (decreased) by 104–105 and the activation energy for variable-range hopping increased 10×. Since GMs are disordered materials, the GM nanostructure should, theoretically, support a universal power law (UPL) response; in practice, that response is generally overwhelmed by resistive (defective) transport. Here, the defect-minimized Mo–SiNx GMs display a superlinear UPL response, which we quantify as the ratio of the conductivity at 1 MHz to that at dc, Δ σ ω. Remarkably, these GMs display a Δ σ ω up to 107, a three-orders-of-magnitude improved response than previously reported for GMs. By enabling high-performance electric transport with a non-noble metal GM, this work represents an important step toward both new fundamental UPL research and scalable, mature GM device applications. [ABSTRACT FROM AUTHOR]

In this work, conventional deep-level transient spectroscopy (DLTS) and high-resolution Laplace-DLTS (L-DLTS) have been used to characterize deep-level traps in (010) β-Ga2O3 epilayers grown by metal organic chemical vapor deposition on native Sn-doped substrates. Two types of epilayers have been studied, one doped with silicon during growth to about 1.5 × 1017 cm−3 and the other type was unintentionally doped (UID). Electrical measurements were conducted on Au and Pt Schottky barrier diodes. In the Si-doped samples, only one electron trap with emission activation energy of 0.42 eV (E0.42) and concentration of (6–8) × 1013 cm−3 has been detected. In the UID samples, in addition to the E0.42 trap, two other traps with activation energies for electron emission of 0.10 eV (E0.10) and 0.53 eV (E0.53) have been observed. Dependencies of electron emission rate (eem) on the electric field (E) as well as concentration-depth profiles {NT(W)} have been measured and analyzed for the E0.10 and E0.42 traps. The eem(E) dependence for the E0.10 trap is characteristic for a donor energy level, while that for the E0.42 trap indicates an acceptor level. The NT(W) dependencies show non-uniform spatial distributions of both the E0.10 and E0.42 traps in the UID samples, with the concentration of the E0.10 trap dropping from about 1 × 1015 cm−3 at 1.5 μm from the surface to about 2 × 1013 cm−3 at 0.5 μm, which indicates out-diffusion from the substrate or interface into the epilayer as a likely source. The results obtained are compared with the literature, and possible origins of the detected traps are discussed. [ABSTRACT FROM AUTHOR]

The structural parameters, electron localization functions, electron paramagnetic resonance (EPR) parameters, formation energies, and thermodynamic transition levels of various oxygen vacancy defects in amorphous silica are comprehensively and integrally investigated by using density functional theory. The trends of changes in the oxygen vacancy defect structure and electron localization induced by the increase in distance between defective silicon atoms are clearly identified. It is shown that the dimer configuration may be the potential structure of the E δ ′ center. For the back-projected unpuckered configuration and the puckered configuration, whose EPR parameters are more consistent with the experimental values of the E γ ′ center, the unpaired electron localized on the sp3 hybridized silicon atom is a common feature. Due to the three-coordinated oxygen atom in the forward-oriented configuration, the EPR parameters are closest to those of the E α ′ center. Transformations of oxygen vacancy defects under different charge states are studied by sequentially adding and removing electrons. The thermodynamic transition level analysis reveals that the dimer and forward configurations may behave as deep traps for electron accumulation. The back-projected puckered fourfold-coordinated and fivefold-coordinated configurations are comparatively stable and may be able to function as shallow traps for electron transport. The neutral double unpuckered, neutral back-projected puckered fourfold-coordinated, and neutral back-projected unpuckered configurations are more likely to lose electrons during hole trapping. As the bias voltage is repeatedly changed, the defect density of the puckered configuration may reduce, while that of the dimer and unpuckered configuration may take an opposite trend. [ABSTRACT FROM AUTHOR]

4H-SiC/ SiO 2 interface states play a major role in the performance and reliability of modern 4H-SiC metal–oxide–semiconductor field effect transistors (MOSFETs). To gain new insights into these interface states, we developed a cryogenic measurement technique that uses photon-assisted electron depopulation to probe device performance limiting 4H-SiC/ SiO 2 interface states. This technique enables the characterization of shallow as well as deep states at the 4H-SiC/ SiO 2 interface of fully processed devices using a cryogenic probe station. Our method is performed on n-channel 4H-SiC MOSFET test structures with deposited oxide and postoxidation anneal. We identify conditions under which the electrons remain trapped at 4H-SiC/ SiO 2 interface states and trigger the controlled photon-assisted electron depopulation within a range of photon energies. This allows us to prove the presence of near interface traps, which have previously been found in thermally grown 4H-SiC MOS structures. Our results are supported by device simulations. Additionally, we study the impact of irradiation intensity and light exposure time on the photon-induced processes. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of volume traps intentionally introduced into a silicon-on-insulator (SOI) substrate by inserting a layer of polysilicon beneath buried oxide. In radio frequency applications, this type of substrate, referred to as trap-rich, is known to considerably reduce the generation of harmonics resulting from the parasitic non-linear charge dynamics introduced by the substrate handler under the buried oxide. This analysis focuses on a test vehicle in the form of an integrated coplanar waveguide on two types of substrates, namely, high-resistivity SOI substrates with and without a trap-rich layer. From a modeling point of view, a simulation methodology is implemented in order to convert the 3D simulation of the coplanar waveguide into a 2D treatment that takes into account the wave propagation effect associated with the distributed nature of the transmission line. As a first step, this modeling strategy is implemented to reproduce the effect of increasing substrate resistivity on 2nd and 3rd harmonic reductions, leading to an excellent agreement with experimental data. Building on this validation of the simulation method, we have opted to simulate the non-linear response of the transmission line on the SOI trap-rich substrate by simplifying the trap distribution model. To avoid the adoption of unverified and strongly process-dependent trap distributions across the bandgap, a midgap monovalent trap density has been introduced, either acceptor or donor density. A monovalent density of acceptor traps with a concentration of 1016 cm−3 and a carrier lifetime of 0.1 ns has been shown to reproduce the experimental data very accurately with a substantial reduction in 2nd and 3rd harmonics. A detailed analysis of the displacement current waveforms explains the beneficial role of acceptor traps compared with donor traps. [ABSTRACT FROM AUTHOR]

Ultra-thin solar cells display high intrinsic radiation tolerance, making them interesting for space applications. This study investigates the dependence of the open-circuit voltage degradation and overall current–voltage behavior of devices with 80 nm thick GaAs absorber layers, on their absorber layer doping concentration and the radiation type used to introduce damage. The radiation types used were 1 MeV electrons and 20 keV, 100 keV, and 1 MeV protons. It is shown that the open-circuit voltage degradation rate increases with absorber layer doping concentration. This is linked to the increase in trap-assisted tunneling enhancement of the recombination rate, facilitated by the increase in electric field strength in the absorber layer with doping concentration. Trap-assisted tunneling is also found to contribute to the high local ideality factors observed in these devices, exceeding values of 2, and to be responsible for the trend of an increasing ideality factor with doping concentration. The significant role of trap-assisted tunneling in the devices is established through fitting of dark current–voltage data using a custom recombination–generation model. An open-circuit voltage degradation rate and local ideality factor curves are also shown to vary with radiation type, despite accounting for their differences in non-ionizing energy loss. This is corroborated by corresponding trends in carrier lifetime damage constants, extracted from the fitting of the dark current–voltage curves. This suggests that the introduction or behavior of radiation damage differs between ultra-thin and conventional, thicker solar cells, where non-ionizing energy loss theory tends to be reliable, especially over the studied proton energy range. [ABSTRACT FROM AUTHOR]

Loading of WS2 can greatly improve water splitting H2 generation efficiency of CdS in experiments. Here, we constructed WS2/CdS(100) and WS2/CdS(110) heterostructures with smaller mismatches and explored their interaction energy and band offset by first-principles calculations. Our calculation suggests that the WS2/CdS(100) interface with a stronger binding energy is more active in experiments, while the WS2/CdS(110) interface is metastable. The band alignment between CdS and WS2 is highly dependent on the orientation of the interfaces, and WS2/CdS(100) and WS2/CdS(110) belong to type-I and type-II band alignments, respectively. Therefore, a metal electrode and hole scavenger may be essential in experiments to help WS2/CdS(100) efficiently trap electrons, and a suitable substrate and an appropriate growth temperature are also needed to composite the CdS(110) surface to achieve a higher photocatalytic efficiency. In addition, we performed a detailed analysis of the macroscopic average potential and found that the calculated accuracy of potential difference across the heterostructures due to slab thickness is less than 80 meV at WS2/CdS interfaces. In total, our calculations not only explain the physical reasons for the increased efficiency of WS2/CdS, but also provide a detailed guideline for the design of a more efficient synergistic catalyst. [ABSTRACT FROM AUTHOR]

A ledge feature in the capacitance–voltage (CV) profiles of Ga2O3 MOS (metal–oxide–semiconductor) capacitors is investigated using UV-assisted CV measurements. A model is presented whereby the capacitance ledge is associated with carrier trapping in deep-level states at the Al2O3/Ga2O3 interface. Following UV assisted emptying of interface traps at a constant bias, a voltage ramp toward flatband results in a CV ledge when the trap recombination current becomes equal to the quasi-static sweep charging current. The ledge continues until all the traps below the corresponding pinned surface potential have been filled. Varying the UV energy varies the ledge voltage range and allows a density of states to be determined as a function of energy. A broad interface state peak with maximum density ∼8 × 1012 cm−2 eV−1 for deep trap energies lying between 2.4 and 4.1 eV below the conduction band (CB) edge is extracted. Using the conductance method, the interface trap density is also found to rise toward the CB edge in the range 0.25–0.45 eV below the CB edge, reaching a maximum density of ∼1 × 1012 cm−2 eV−1. Combining these two techniques, an interface trap distribution is estimated for almost the entirety of the bandgap of Ga2O3. This novel technique probes deep interface states where standard methods fail to quantify interface states reliably. [ABSTRACT FROM AUTHOR]

The ultra-wide bandgap of gallium oxide provides a rich plethora of electrically active defects. Understanding and controlling such defects is of crucial importance in mature device processing. Deep-level transient spectroscopy is one of the most sensitive techniques for measuring electrically active defects in semiconductors and, hence, a key technique for progress toward gallium oxide-based components, including Schottky barrier diodes and field-effect transistors. However, deep-level transient spectroscopy does not provide chemical or configurational information about the defect signature and must, therefore, be combined with other experimental techniques or theoretical modeling to gain a deeper understanding of the defect physics. Here, we discuss the current status regarding the identification of electrically active defects in beta-phase gallium oxide, as observed by deep-level transient spectroscopy and supported by first-principles defect calculations based on the density functional theory. We also discuss the coordinated use of the experiment and theory as a powerful approach for studying electrically active defects and highlight some of the interesting but challenging issues related to the characterization and control of defects in this fascinating material. [ABSTRACT FROM AUTHOR]

We present a technique for measuring the interactions between pairs of colloidal particles in two optical traps. This method is particularly suitable for measuring strongly attractive potentials, an otherwise challenging task. The interaction energy is calculated from the distribution of inter-particle separations by accounting for the contribution from the optical traps with arbitrary trap profiles. The method is simple to implement and applicable to different types of pair potentials and optical trapping geometries. We apply the method to measure dipolar pair interactions in experiments with paramagnetic colloids in external magnetic fields. We obtain consistent and accurate results in all regimes, from strongly attractive to repulsive potentials. By means of computer simulations, we demonstrate that the proposed method can be successfully applied to systems with complex pair interactions characterized by multiple attractive and repulsive regimes, which are ubiquitous in soft and biological matter. [ABSTRACT FROM AUTHOR]

We report the electrical properties, deep trap spectra, and diffusion lengths of non-equilibrium carriers in Ni Schottky diodes and NiO/Ga2O3 heterojunctions (HJs) prepared on the same n−/n+ β-Ga2O3 epi structures. The heterojunctions decrease the reverse current of Ga2O3 high-power rectifiers. In HJs, in contrast to Schottky diodes, the capacitance and AC conductance show a prominent frequency and temperature dependence, suggesting the presence of two temperature activation processes with activation energies of 0.17 and 0.1 eV. The deep trap spectra of the Schottky diodes and HJs differ by the absence in the HJ of deep electron traps E2* with level near Ec − 0.7 eV considered to be an important center of non-radiative recombination. This correlates with the observed increase in the diffusion length of non-equilibrium charge carriers in the HJs to 370 nm compared to 240 nm in the Schottky diodes. The diffusion length of charge carriers in p-NiO was found to be quite short, 30 nm. Possible reasons for the observed differences and possible origin of the minority-trap-like feature commonly reported to be present in the deep level spectra of HJs and also observed in our experiments are discussed. [ABSTRACT FROM AUTHOR]

Glow-in-the-daylight is a fascinating luminescence phenomenon displayed by certain storage phosphors that emit ultraviolet light upon being stimulated by ambient lighting. In this study, we investigate the influence of indoor lighting on the glow-in-the-daylight emission of a co-doped garnet phosphor, Y3Al5O12:Pr3+,Eu3+, known for its deep trap that effectively retains energy. Our experimental results demonstrate an interesting observation that, following x-ray radiation at room temperature, this phosphor exhibits negligible persistent luminescence in darkness but emits intense ultraviolet light peaking at 318 nm under indoor lighting conditions. This emphasizes the crucial role played by ambient lighting in releasing stored energy. Our findings not only shed light on the influence of indoor illumination dose and spectral distribution on the persistently stimulated luminescence but also expand our exploration to various ultraviolet phosphors with deep traps, with the aim of uncovering novel materials applicable in glow-in-the-daylight scenarios. [ABSTRACT FROM AUTHOR]

Nanowires (NWs) composed of 2,4-bis[(4-diethylamino)-2-hydroxyphenyl] squaraine were prepared by evaporation-induced self-assembly (EISA). NWs were ∼560 nm wide (aspect ratios: 10–90). X-ray diffraction analysis indicated polymorphism (monoclinic/triclinic). Optical data reported the triclinic phase with energetic disorder. Given the favorable alignment of the Au work function and squaraine HOMO energy, symmetric, unipolar metal–insulator–metal devices were formed by the EISA of NW meshes on inter-digitated Au electrodes. Room temperature DC I–V characteristics displayed hysteretic I–V loops, indicating memristive behavior. At low bias, data indicated Ohmic transport with carrier extraction facilitated by thermionic emission. At high biases, devices exhibited space-charge-limited conduction in the presence of shallow traps. At 77 K, data indicated Ohmic transport at low bias with carrier extraction by thermionic emission while, at high biases, trap-limited space-charge-limited conduction in the presence of traps distributed in energy, with carrier extraction by Fowler–Nordheim tunneling, was observed. The I–V hysteresis was eliminated at 77 K and attenuated by fast scan rates at room temperature, suggesting that carrier trapping/de-trapping underpinned the hysteresis. In impedance measurements, the device response fitted a Randles equivalent circuit indicating purely electronic conduction. By applying voltage waveforms, I–V hysteresis and analog resistive switching (memristive) functionality were observed. Device conductance could be increased sweep by sweep, giving conductance tuning through distinct states, with wait time- or voltage-erase options, consistent with trap filling/emptying effects. Repeated erase–write–read of multiple distinct states over many voltage cycles during continuous use in air was demonstrated. Finally, synaptic functions, e.g., pulse-dependent plasticity, and short- to long-term memory transition, were successfully emulated. [ABSTRACT FROM AUTHOR]

Photomultiplication-type organic photodetectors (PM-OPDs) have been stimulating more and more researchers' interest owing to their extremely high external quantum efficiency (EQE). To prepare high-performance PM-OPDs with a broadband spectral response range from visible to near-infrared and investigate the role of energy levels of the donor and acceptor on its responsiveness, the non-fullerene acceptor Y6 was added into the P3HT:PC71BM system in this work. The photomultiplication phenomenon with the highest EQE has been achieved under both forward and reverse bias when the ratio of Y6 in two acceptors approaches 80 wt. %. The introduction of Y6 not only promotes the formation of moderate hole traps in the active layer but also results in an appropriate amount of low injection barriers to allow more electron injection from the external circuit. Therefore, the spectral response of the device with 80 wt. % Y6 has been broadened from 750 to 950 nm, and the champion EQE of 15 691% at 10 V and 7639% at −20 V at 850 nm was achieved. This work reveals the importance of hole-trapping ability determined by the energy level difference between the donor and the acceptor for the selection of the multiplication system and provides a scheme for the design of high-performance broadband PM-OPDs. [ABSTRACT FROM AUTHOR]

Hafnium oxide (HfO2) has been explored as high-κ gate dielectrics in scaled CMOS devices, artificial synapses to be used in neuromorphic computing to achieve brain-like functionalities, a storage layer in memory devices, a piezoelectric energy harvester, and a photodetector. In this article, the origin of a native defect present in the HfO2 thin films on silicon is experimentally probed using deep level transient spectroscopy (DLTS) technique. It was realized that defects (predominantly oxygen vacancies) in HfO2 segregate near the Si/HfO2 interface. The interfacial and bulk HfO2 trap charges are communicating through the tunneling/ hopping, and, finally, they are emitted to the respective bands of silicon depending on the silicon used. We have observed four prominent defect states, and we believe that all these belong to oxygen vacancies in different charge states. The activation energies of trap states are in the range of 1.22–2.02 eV from the HfO2 conduction band edge, and they fall in front of the Si bandgap in the band alignment of the Al/HfO2/Si gate stack. The capture cross sections of these traps are measured with insufficient filling DLTS and found to be of the order of 10−19 cm2. The results provide valuable insights into realizing the behavior of oxygen vacancy-related deep defects in HfO2 and guide their possible impact on the device performance. [ABSTRACT FROM AUTHOR]

Most semiconductors exhibit a saturation of free carriers when heavily doped with extrinsic dopants. This carrier saturation or "doping limit" is known to be related to the formation of native compensating defects, which, in turn, depends on the energy positions of their conduction band minimum and valence band maximum. Here, we carried out a systematic study on the n-type doping limit of GaAs via ion implantation and showed that this doping limitation can be alleviated by the transient process of pulsed laser melting (PLM). For n-type doping, both group VI (S) and amphoteric group IV (Si and Ge) dopants were implanted in GaAs. For comparison, p-type doping was also studied using Zn as the acceptor. Implanted dopants were activated by the PLM method, and the results are compared to rapid thermal annealing (RTA). Our results reveal that for all n-type dopants, while implantation followed by the RTA results in a similar saturation electron concentration of 2–3 × 1018 cm−3, the transient PLM process is capable of trapping high concentration of dopants in the substitutional site, giving rise to a carrier concentration of >1019 cm−3, exceeding the doping limit of GaAs. However, due to scatterings from point defects generated during PLM, the mobility of n-type GaAs after PLM is low (∼80–260 cm2/V s). Subsequent RTA after PLM (PLM + RTA) is able to remove these point defects and recover the mobility to ∼1000–2000 cm2/V s. The carrier concentrations of these PLM + RTA samples are reduced but are still a factor of 3 higher than RTA only GaAs. This can be understood as the dopants are already incorporated in the substitutional site after PLM; they are less likely to be "deactivated" by subsequent RTA. This work is significant to the understanding of doping mechanisms in semiconductors and provides a means for device applications, which require materials with ultra-high doping. [ABSTRACT FROM AUTHOR]

Using the novel process of hot N+-ion implantation at 800 °C into Si quantum dots (Si-QDs) with approximately 3.2 nm fabricated by hot Si+-ion implantation into an SiO2 layer and post-Ar annealing, we experimentally demonstrated that the photoluminescence intensity (IPL) of the Si-QDs increased with increasing N+-ion dose (D N + ). Post-N2 high-temperature annealing without hot N+-ion implantation, as a reference process, also increased the IPL of Si-QDs, because N atoms trapped within Si-QDs, which was evaluated by secondary ion mass spectrometry, terminate the dangling bonds within Si-QDs and at the Si/SiO2 interface. Additionally, the IPL of Si-QDs showed the maximum value at the optimal D N + of 5 × 1015 cm−2, which was 1.4-fold higher than that observed without hot N+-ion implantation. With a short post-annealing time (<60 min), the increase in IPL owing to N+-ion implantation was considerably larger than that caused by N2 annealing, which is likely due to the efficiency of the termination of the dangling bonds of the Si-QDs by the N+-ions. This is an advantage of the hot N+-ion implantation technique. Forming gas annealing after furnace annealing also induced a larger IPL than that observed before forming gas annealing. However, the maximum IPL observed after forming gas annealing was completely independent of the conditions of furnace annealing and D N + . This suggests that the perfect termination of the dangling bonds of the Si-QDs may be realized via forming gas annealing after furnace annealing. [ABSTRACT FROM AUTHOR]

In this paper, we report an analysis of reverse current mechanisms observed in GaN Schottky barrier diodes leading to hysteretic behavior of the I–V curves at low temperature. By means of DC measurements from 33 to 475 K, we demonstrate the presence of two leakage mechanisms when comparing the experiments with the results obtained using a unified model to predict the ideal reverse current of the diode. Poole–Frenkel emission is the dominant mechanism for temperatures above 200 K, while trap-assisted tunneling prevails for lower temperatures, where also, hysteresis cycles are revealed by means of DC dual-sweep voltage measurements. The energy of the corresponding traps has also been determined, being around 0.2 and 0.45 eV, respectively. The hysteresis phenomenon is attributed to the bias-induced occupancy of the energy states originating the leakage-current processes, which leads to the reduction of the reverse current after a high negative voltage is applied to the diode. [ABSTRACT FROM AUTHOR]

Ferrite compounds have gained scientific attention for their multifunctional attributes. This investigation explores the structural, optical, dielectric and conductivity properties of polycrystalline γ-Fe 2 WO 6 synthesized by the solid state route. The X-ray diffraction confirmed the orthorhombic structure and single-phase formation, while the electron microscopy showed uniform distribution of dense micrometer-sized grains in γ-Fe 2 WO 6. The FTIR spectroscopy analysis validated the presence of active stretching and bending modes, signifying oxygen anion vibration at both Fe and W sites. The simultaneous presence of Fe2+ and Fe3+ ions in the matrix, as confirmed by X-ray photoelectron spectroscopy (XPS), results in an augmented optical energy band gap and contributes to dielectric permittivity due to the charge carrier hopping mechanism between the trap sites. The compound manifests semiconductor attributes, evident in its indirect optical band gap measuring 1.7 eV. It is observed that the compound has effectively degraded the Methylene Blue (MB) under the visible light within 40 min with a degradation efficiency up to 63 %. The material's electrical conductivity, follows the Jonscher's power law, signifies its semiconductor nature and adheres to the Small Polaron tunneling model for charge conduction between neighboring sites. The impedance (Z′) curves exhibit dielectric relaxation (≤ 10 kHz) with a similar activation energy to the dc conductivity study. The activation energy, determined from both the impedance and conductivity analyses, indicates a connection with the migration of oxygen vacancies within the material. Our observation reveals the presence of oxygen vacancies, which possibly act as in-gap electron traps, enhancing the correlated optical and ac conductivity properties, making it an appealing material for diverse multifunctional applications. [ABSTRACT FROM AUTHOR]

A highly efficient photoelectrochemical (PEC) strategy was proposed for the determination of ascorbic acid (AA). Cerium-doped tungsten trioxide (Ce-WO3) microrods were synthesized by a hydrothermal method and further characterized through transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. Thereafter, they were deposited onto a cleaned fluorine-doped tin oxide (FTO) glass forming the working electrode as the photoactive material. Under strong visible light irradiation, the resulting PEC sensing platform generated the corresponding electron–hole pairs, converting light signals into electrical signals. Ascorbic acid served as a good electron donor to trap holes for improvement of photocurrent responses on Ce-WO3/FTO. Besides, the strength of photocurrent signals versus the logarithm of ascorbic acid concentration showed a good linearity over the ascorbic acid concentration range of 100–4000 nM and the limit of detection (LOD) was estimated to be 28.6 nM. Importantly, this PEC sensor had a fast response, high sensitivity, and distinguished selectivity for detecting ascorbic acid. In addition, it also had the features of being simple to fabricate, low production cost, and portable, which made it a promising means of ascorbic acid determination. [ABSTRACT FROM AUTHOR]

Due to increasing global energy demands and environmental concerns, the search for alternative and environmentally friendly energy sources is of paramount importance. Solid oxide fuel cells (SOFCs) have emerged as a promising solution thanks to their high efficiency and minimal environmental impact. In this regard, perovskite oxides, with their unique properties, have attracted significant attention. This study investigates the dielectric dispersion, electrical features, scaling behavior, and optical defects of Ca 0.67 La 0.22 Ti 0.85 Cr 0.15 O 3 with x = 0.15, CLT 0.85 Cr 0.15. The presence of a vacancy in the A-site is denoted by the square in the formula. Relaxation phenomena were analysed using dielectric and modulus formalism, while the conductivity mechanism was explored through electrical conductivity measurements. The optical defects of CLT 0.85 Cr 0.15 were analysed using electron paramagnetic resonance (EPR) spectroscopy. The findings revealed the formation of Cr3+–VO center defects. These defects serve as sources of in-gap electron traps, thereby enhancing the optical properties of CLT 0.85 Cr 0.15 , making it as a compelling material for various optical applications. The power density increased with temperature, reaching 0.73 W/cm2 at 850 °C, suggesting that CLT 0.85 Cr 0.15 could be a promising electrolyte for IT-SOFCs. The peak in power density correlated with temperature due to thermal effects on ion motion. However, the open circuit voltage decreased with temperature increase, due to increased oxygen vacancies and electron/hole conduction in CLT 0.85 Cr 0.15. The findings suggest that perovskite materials could revolutionize SOFCs technology, paving the way for more efficient and environmentally friendly energy solutions. [ABSTRACT FROM AUTHOR]

The luminescent properties of europium (Eu) doped BaAl2O4 phosphors were strongly influenced by post-annealing temperatures for blue-green persistent luminescence and latent fingerprints (LFPs). The X-ray powder diffraction patterns of the BaAl2O4: 1 mol% Eu nanophosphor, annealed between 1000 and 1300 °C, indicated a hexagonal ferroelectric phase. The X-ray photoelectron spectroscopy (XPS) revealed that the Ba atoms occupied two different sites in the BaAl2O4. The XPS and photoluminescence (PL) results revealed the presence of Eu3+ and Eu2+ states. The Eu-doped BaAl2O4 showed the characteristic red emission of Eu3+ at 251 and 464 nm excitations, while excitations at 340 and 380 nm showed yellowish-green emission. Strong evidence of energy transfer between a charge transfer band and the different energy levels of Eu2+ and Eu3+ ions was obtained. The existence of the Cr ion impurity in the aluminates was confirmed with UV-VIS diffuse reflectance and PL spectroscopy. The present results suggested that and O′′i defects have introduced electron and hole traps in the host that acted as luminescent centers for persistent luminescence. LFPs detection using BaAl2O3:Eu2+/Eu3+ phosphor showed an excellent marking agent for applications in forensic science. [ABSTRACT FROM AUTHOR]

The substitution of noble metals with cost-effective copper nanoparticles (Cu NPs) in the preparation of metal/semiconductor composite catalysts holds significant environmental and economic implications for the degradation of various organic pollutants. However, the development of highly active and stable Cu NPs catalysts has emerged as a key challenge in the progression of non-noble metal catalysts. In this study, the reducibility of glutathione (GSH) was employed to reduce Cu2+ to Cu NPs, resulting in the formation of stable Cu-GSH nanoparticles through S–H bonds. An electrostatic self-assembly strategy was used to load Cu-GSH onto WO3 nanorods, thereby designing a Cu GSH/WO3 catalytic material with highly efficient charge transport efficiency. Under visible light irradiation, 3 wt% Cu GSH/WO3 demonstrated excellent degradation performance for organic pollutants, achieving the degradation of 99.8% of Rh B and 98.6% of TC within 60 minutes. Experimental results from photoelectrochemical (PEC) and electron spin resonance (ESR) analyses indicated that Cu GSH functions as an efficient electron trap, which triggers electron flow driven by the Schottky barrier, capturing the photoexcited electrons from WO3. This greatly enhances the separation efficiency of WO3 carriers and extends the lifetime of the carriers. It is hoped that this work will provide a viable approach for the synthesis of new high-efficiency composite photocatalytic materials. [ABSTRACT FROM AUTHOR]

Vacancy engineering is a highly efficient approach to enhancing photocatalytic activity. This research presents an innovative development of ZnO/NiO coaxial heterojunction nanofibers (ZN 1/1) and ZnO/NiO coaxial heterojunction nanofibers with engineered oxygen vacancies (OVs-ZN 1/1) via electrospinning and annealing. Detailed characterization of the nanofiber microstructure was conducted using scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The OVs-ZN 1/1 nanofibers demonstrated outstanding and unprecedented photocatalytic performance, achieving a 99 % degradation rate of Congo red dye (CR) under simulated solar light in just 45 min, with a good degradation coefficient of 0.091 min−1. Remarkably, the nanofibers' photocatalytic activity remained a high level even after five cycles. Moreover, the photocatalytic H 2 O 2 yield of OVs-ZN 1/1 increased 20 times as much as that of ZN 1/1. Experiments and mechanism analysis indicate that oxygen vacancy, as the electron trapping site of photoexcitation, accelerates the charge separation and transfer at the interface, thus promoting the adsorption and activation of target molecules. This study highlights the novel and superior performance of photochemical catalysts achieved through the strategic incorporation of oxygen vacancies and heterojunctions. [Display omitted] • Utilize coaxial electrospinning to fabricate high-density ZnO/NiO heterojunction nanofibers. • Enhance the photocatalytic performance of the nanofibers by generating oxygen vacancies (OVs). • OVs-ZN 1/1 efficiently catalyze Congo red degrading and H 2 O 2 production under simulated sunlight. [ABSTRACT FROM AUTHOR]

The observation of the gate-controlled supercurrent (GCS) effect in superconducting nanostructures increased the hopes for realizing a superconducting equivalent of semiconductor field-effect transistors. However, recent works attribute this effect to various leakage-based scenarios, giving rise to a debate on its origin. A proper understanding of the microscopic process underlying the GCS effect and the relevant time scales would be beneficial to evaluate the possible applications. In this work, we observed gate-induced two-level fluctuations between the superconducting state and normal state in Al/InAs nanowires (NWs). Noise correlation measurements show a strong correlation with leakage current fluctuations. The time-domain measurements show that these fluctuations have Poissonian statistics. Our detailed analysis of the leakage current measurements reveals that it is consistent with the stress-induced leakage current (SILC), in which inelastic tunneling with phonon generation is the predominant transport mechanism. Our findings shed light on the microscopic origin of the GCS effect and give deeper insight into the switching dynamics of the superconducting NW under the influence of the strong gate voltage. It was recently shown that a voltage could be used to control a supercurrent in superconducting nanostructures, much like a transistor, however, the exact origin of this effect has been debated. Here Elalaily et al. show via noise measurements that the suppression of the supercurrent in the superconducting device arises due to excitation emission by inelastic tunneling of the electrons through the trap states created by stressing the oxide layer between the gate and the NW under a high electric field. [ABSTRACT FROM AUTHOR]

The study of charge transfer in thin film solar cells made of several layers is of high importance since they may lose their energy via the recombination process at the interfaces, specifically at the interface of the electron transport layer (ETL) and perovskite. Titanium dioxide (TiO2) is mostly used as an ETL in perovskite solar cells due to its many advantages. However, TiO2 has some disadvantages, such as low electron mobility compared to the perovskite layer and electron trap states on its top at the interface. These effects cause the accumulation of carriers at the ETL/perovskite interface then the non-radiative recombination will be enhanced, which is considered as one of the significant losses in the Perovskite Solar Cells (PSCs). In this work, a new technique is taken for more optimal ETL doping. We fabricated the ETL layers with graded doping of platinum quantum dots (Pt QDs), in which Pt QDs concentration is high at the ETL/Perovskite interface and zero at the FTO/ETL interface. This strategy not only suppresses the recombination at the ETL/perovskite interface and subsequently enhances the device efficiency from 12.92 to 14.36% but also improves the stability of the PSCs. [ABSTRACT FROM AUTHOR]

The precise design of active sites and light absorbers is essential for developing highly efficient photocatalysts for CO2 reduction. Core–shell heterostructures constructed based on large-sized plasmonic Bi metals are ideal candidates because of the utilization of full-spectrum light and effective charge separation. However, the mechanism of selectivity modulation of large-sized Bi@semiconductor photocatalysts has yet to be explored in depth. Herein, a plasmonic Bi@Bi2O2CO3 core–shell heterostructure was successfully synthesized via a facile solvothermal treatment in deep eutectic solvents, demonstrating highly efficient photocatalytic CO2 reduction. This structure features a sizeable Bi sphere with a thin, epitaxially grown Bi2O2CO3 shell, which allows for the utilization of the entire light spectrum. Additionally, the oxygen vacancies in the Bi2O2CO3 shell can rapidly trap electrons transferred from the Bi core via Bi–O–Bi bonds, thereby forming abundant electron-rich interfaces that serve as the active sites for activating reactant molecules and facilitating the reaction. [ABSTRACT FROM AUTHOR]

Chorus waves induce both electron acceleration and loss. In this letter, we provide significantly improved models of electron lifetime due to interactions with chorus waves. The new models fill the gap that previous models have on some magnetic local time (MLT) sectors of the Earth's magnetosphere. This improvement is critical for modeling studies. The lifetime models developed using two different methods are valid for electrons with an energy range from 1 keV to 2 MeV. To facilitate the integration of these new models into different ring current and radiation belt codes, we parameterize the electron lifetime as a function of L $L$‐shell and electron kinetic energy at each MLT and geomagnetic activity (Kp). The parameterized electron lifetimes exhibit strong dependencies on L $L$‐shell, MLT, and energy. Simulations using these new models demonstrate improved agreement with satellite observations compared to simulations using previous models, advancing our understanding of electron dynamics in the magnetosphere. Plain Language Summary: There are a large number of energetic electrons trapped by our Earth's magnetic field in the near‐Earth space. The regions populated by these high energy electrons are called ring current and radiation belts. It is important to understand the dynamics of the energetic electrons because they can be dangerous to satellites and astronauts flying through these regions. Electromagnetic waves in these regions play an important role in the dynamic of ring current and radiation belt electrons. Among these waves, whistler mode chorus wave is an important wave that can cause both acceleration and loss of the energetic electrons. In our previous studies, we calculated diffusion coefficients to quantify the effect of chorus waves on the energetic electrons. Based on these diffusion coefficients, in this study, we estimate the lifetime of energetic electrons due to their interactions with chorus waves. To make this lifetime model more convenient to be used in different ring current and radiation belt models, we apply polynomial fits to the calculated lifetime. Our new lifetime model is more advanced than previous models, especially in the space coverage. We test the new models in simulations and the results agree better with satellite observations than the previous models do. Key Points: The new lifetime model provides extended space coverage in comparison to current widely used lifetime modelsSuch parameterized lifetimes are very significant for simulations of the dynamics of radiation belt and ring current electronsUsing the new electron lifetime model in simulations improves the agreement between the simulation results and the satellite observations [ABSTRACT FROM AUTHOR]

Luminescent radicals are attracting attention as emitters in electroluminescent devices thanks to the exploitation of doublet excitons. Recent studies reveal that exciton formation in radical organic light‐emitting diodes (OLEDs) primarily occurs through a charge trapping mechanism. Although typically detrimental for OLEDs, this might be a key process to elucidate light emission in organic light‐emitting transistors (OLETs). Here, a unipolar n‐type architecture suitable for the implementation of radical emitters is introduced, designed based on computational calculations. The operation of the as‐realized devices incorporating the newly synthesized [2,6‐dichloro‐4‐(2,6‐dimethoxyphenyl)phenyl](3,5‐dichloro‐4‐pyridyl) (2,4,6‐trichlorophenyl)methyl radical is investigated via transient electroluminescence measurements to demonstrate the occurrence of long‐living emission ascribed to the charge trapping mechanisms. Moreover, a comprehensive understanding of the processes governing radical‐OLET is obtained by recording complete 2D maps of both optical and electrical response of the device as a function of applied voltages. Notably, the trapping of electrons by radical moieties is demonstrated to generate a negative charge density in the emissive layer that facilitates holes to be injected: increasing the balance of opposite charge carriers, a tenfold enhancement of the external quantum efficiency (EQE) at the proper source‐drain and source‐gate voltage conditions is reported to reach a maximum EQE value of 0.2%. [ABSTRACT FROM AUTHOR]

For heterojunction system, the lack of stable interfacial driving force and definite charge transfer channel makes the charge separation and transfer efficiency unsatisfactory. The photoreaction mechanism occurring at the interface also receives less attention. Herein, a 2D/2D Z‐scheme junction BiOBr@NiFe‐LDH with large‐area contact featured by short interface hydrogen bonds and strong interfacial electric field (IEF) is synthesized, and in situ photoinduced metallic species assisting charge transfer mechanism is demonstrated. The hydrogen bonds between O atoms from BiOBr and H atoms from NiFe‐LDH induce a significant interfacial charge redistribution, establishing a robust IEF. Notably, during photocatalytic reaction, Bi0 and Ni0 are in situ performed in heterojunction, which separately act as electron transport mediator and electron trap to further accelerate charge transfer efficiency up to 71.2 %. Theoretical calculations further demonstrate that the existence of Bi0 strengthens the IEF. Therefore, high‐speed spatial charge separation is realized in Bi0/BiOBr@Ni0/NiFe‐LDH, leading to a prominent photocatalytic activity with a tetracycline removal ratio of 88.3 % within 7 min under visible‐light irradiation and the presence of persulfate, far exceeding majority of photocatalysts reported previously. This study provides valid insights for designing hydrogen bonding heterojunction systems, and advances mechanistic understanding on in situ photoreaction at interfaces. [ABSTRACT FROM AUTHOR]

Aromatic organoarsenic compounds (AOCs) have proven to be both a boon and a curse by boosting profit maximization in livestock production and at the same time contributing to the pollution of water bodies, the chief cornerstone of the ecosystem. Interestingly, photocatalytic degradation using nanomaterials has emerged as an effective method to mitigate AOC pollution. Thus, this study aims to review and analyze original research works directed toward the photocatalytic degradation of AOC in the aqueous environment. In this study, the photocatalytic degradation efficiency of various nanomaterials is investigated for different aromatic organoarsenic compounds. In addition, an empirical analysis was conducted on the impact of electron trapping and radical scavengers. Furthermore, photocatalytic degradation kinetics and mechanisms were pragmatically discussed. Also, recyclability, stability, and real‐life applicability were empirically evaluated. According to this review, most nanomaterial materials had maximal photocatalytic degradation efficiencies of >75% for most AOCs within an average time of 6–330 min. The radical scavenging study revealed that ●OH and O2● mechanistically play a major role in AOC degradation than electrons and holes. Additionally, it was shown that expended photocatalysts can be eluted mostly with H2O/NaOH and recycled up to 3–6 rounds with a degradation efficiency of >80% in most cases while maintaining their original structural integrity. This indicates that the method has the potential to be both environmentally friendly and industrially scalable. Ultimately, research gaps were highlighted, which can help researchers identify future research hotspots and open doors for technique advancement. [ABSTRACT FROM AUTHOR]

Mechanoluminescence (ML) is a fascinating phenomenon with diverse applications in pressure sensing, damage detection, and stress distribution visualization. However, most ML materials exhibit instantaneous photon emission that requires real‐time recording with a photodetector, and thereby circumscribing their applicability predominantly to real‐time stress‐sensing scenarios. In this work, a novel method is introduced for non‐real‐time stress sensing utilizing Li0.1Na0.9NbO3:Pr3+ phosphor, which allows for the retrieval of pressure location and intensity even 20 days after the event. The influence of heat and pressure on the trap depth distribution is analyzed using thermoluminescence (TL) and ML measurements, and it is proved that both heat and pressure release the captured electrons in the same traps. Leveraging the intricate competition between mechanical and thermal detrapping processes, stress information can be accessed through TL imaging. Furthermore, an algorithm is proposed based on this phenomenon to authenticate the stress information. This research not only advances the fundamental understanding of ML phenomena but also introduces a novel approach for applications such as mechano‐history indicators, security papers, and advanced data storage systems. [ABSTRACT FROM AUTHOR]

In this study, a novel Z-scheme heterojunction based on g-C3N4/TiO2/NiCo2O4 nanocomposite was synthesized using a combination of hydrothermal and ultrasonic methods and investigated the photocatalytic degradation of Rhodamine B (RhB) dye. The synthesized nanocomposite was characterized XRD, FT-IR, FE-SEM, TEM, EDS, PL, UV–Vis DRS techniques. Subsequently, various parameters such as the effect of NiCo2O4 amount in the composite structure, pH, initial pollutant concentration, photocatalyst dosage, and different scavengers were investigated to determine the exact mechanism of the photocatalytic process. In different concentrations of NiCo2O4, the base value (X: 1) was determined as the optimal value in photocatalytic degradation. g-C3N4/TiO2/NiCo2O4 composite had the highest percentage of 99.5% Rh.B dye degradation in 60 min. In addition, by examining the pH, it was found that its optimal value is 7, and the rate of dye degradation in this condition is more than other materials, and the rate constant value is 0.069 min–1. In addition, the g-C3N4/TiO2/NiCo2O4 catalyst showed good performance for each reuse and retained about 82% of its initial photocatalytic activity after 5 cycles. The results indicate that photoinducd (RhB) holes play a crucial role in the photocatalytic degradation of RhB in the presence of the g-C3N4/TiO2/NiCo2O4 nanocomposite via pair Z-scheme system. In the Z-scheme system, the rapid recombination between the hole-electron pair is not observed due to the electron trapping effect of the needle-shaped NiCo2O4 structure, resulting in high photocatalytic efficiency and dye degradation. Therefore, Z-scheme systems are efficient and effective for the removal of water pollutants. [ABSTRACT FROM AUTHOR]

Constructing heterostructure is a promising strategy to enhance photocatalytic performance. Here, a cyano and carbon dots/polypyrrole (CDs/PPy) co‐modified carbon nitride (CPKCN) heterostructure is constructed for photocatalytic H2O2 generation. It is interestingly found that the intermediates formed during the oxidation polymerization of pyrrole can be the potential electron trapping sites and reactive sites. In addition, the localized photoheat produced by CDs/PPy also plays an active role in improving photocatalytic activity. Moreover, the addition of CDs/PPy leads to a higher negative zeta potential of CPKCN, which is favorable for the attraction of the sample surface to H+. These features, plus the positive effect of cyano groups, collectively boost the charge transfer and improve the selectivity of two‐electron O2 reduction. Therefore, the enhanced photocatalytic H2O2 generation performance of the developed CPKCN is achieved, with an H2O2 generation rate of 3.7 mmol g−1 h−1 under visible light in a 10 vol% isopropanol (IPA) aqueous solution, and with the apparent quantum yield of 16.7% at 420 nm and the solar‐to‐chemical conversion efficiency of 0.34%. The work offers new insights into developing efficient photocatalysts for various applications. [ABSTRACT FROM AUTHOR]

Space charge-limited currents in Ti–TiO2 thin-film structures have been studied. Using the experimental physical parameters of the TiO2 dielectric, models of the formation of the space charge-limited injection currents have been constructed. The dependences of the injection current on the applied voltage, dielectric layer thickness, and parameters of electron traps have been explored. It is shown that the space charge-limited injection currents in the investigated structures depend significantly on both the depth and concentration of traps. The results obtained are compared with the dependences obtained previously for the BeO, Al2O3, and AlN structures. [ABSTRACT FROM AUTHOR]

Since their discovery, clathrate hydrates (CHs) have received great attention both from theoretical and experimental aspects due to their great potential for gas storage and prospective applications as icy crystal materials. However, there has been limited research on the decomposition, reduction or other reactions of gases enclosed in CHs. Thanks to their unique hydrogen bonding network and cavity structures, CHs can serve as the promising nanoreactors to achieve chemical conversions, e. g. reducing greenhouse gases. In this review‐type article, we characterize the potential performance of such CHs nanoreactors by discussing their multiple functions including important roles of hydrogen bonds in CHs, e. g. the confinement effect and proton source, and then discuss the enhanced electron‐binding ability of guest molecules and the structures and properties of trapped electrons in the stacked nanocages, which contribute to our understanding of chemical reactions occurring in CHs. Finally, we provide detailed analyses of representative reaction mechanisms underwent in CH nanoreactors and effective calculational and molecular dynamics simulation methods. This review‐type article aims to provide a detailed summary about the functional characteristics of CHs and reactivity in CHs, which make CHs a kind of promising icy nanoreactors. [ABSTRACT FROM AUTHOR]

The study of polaron dynamics in complex materials has garnered significant attention owing to its implications for various technological applications, including catalysis, solid‐state devices, and energy storage. This paper investigates the photo‐excited electron and hole polaron dynamics in cerium dioxide (CeO2) using time‐resolved X‐ray absorption spectroscopy, with an emphasis on the nano‐size effect. Additionally, density functional theory and multiplet calculations have been utilized to reveal the photo‐excited polaron dynamics in CeO2 single crystal (SC) and nanocrystal (NC). The electron polaron is observed to decay into a deep trap site with a short duration of ≈5 ps, while electrons in the traps stay for more than 1400 ps. The most significant observation is the behavior of holes in NC, which tends to stay longer (≈150 ps) compared to SC (<10 ps) suggesting hole existence more at the surface than at bulk. The fast dissociation of the electron polarons the prolonged lifetime of the electrons above the Fermi level and the enhanced hole lifetime at the surface are proposed to be among the various factors that influence the high reactivity of CeO2. [ABSTRACT FROM AUTHOR]

Persistent luminescence materials have been widely studied due to their excellent optical properties. However, they can only be activated by UV light; in other words, the charging method for these phosphors is limited. In fact, materials that can continuously emit light when exposed to sunlight are highly sought after for their potential to reduce energy consumption. Warm‐colored persistent luminescence materials are particularly useful for information storage, security marking, and preventing counterfeiting. Nevertheless, creating effective warm‐color persistent luminescence materials that are activated by sunlight remains a challenging task. To address this issue, novel daylight‐activated red persistent luminescence materials, Gd3‐xCax‐0.02GaO6:0.02Eu2+ (x = 0.3 ‐ 0.7) are explored. The material can be effectively activated by sunlight under all weather conditions, as well as by bright light from indoor lamps, mobile phone screens, and any form of visible light. Moreover, it possesses excellent water resistance. The process of electron trapping and release within the material is investigated through thermoluminescence experiments, photoluminescence spectra, and persistent luminescence spectra. Importantly, this phosphor has been demonstrated for various applications, including night vision marking, anti‐counterfeiting, optical information storage, and positioning, among others. [ABSTRACT FROM AUTHOR]

The persistent luminescent (PSL) phosphors Sr 2- x - y MgSi 2 O 7 : x Eu2+, y Dy3+ (x = 0∼0.08, y = 0∼0.08) were synthesized by a solid-state reaction method in a weak reductive atmosphere of 5%-H 2 /N 2. Comprehensive measurements were carried out to study the effects of Eu2+ and Dy3+ doping amount on the crystal phase, photoluminescence (PL), afterglow decay properties, and trap energy levels. The results indicated that the impurity phases decreased and disappeared, and crystalline grains tended to be larger and denser with the doping amount of Eu2+ and Dy3+ increasing. We shed light on the origination of asymmetric PL peak, concentration quenching of Eu2+ ions, time evolution of PSL specture and chromaticity of Eu2+, Dy3+ co-doped phosphors. Based on the deconvolutions of X-ray photoelectron spectroscopy (XPS) spectra and thermoluminescence (TL) spectra, the types and energy depth of traps in these phosphors were systematically studied. According to the data of PL, PLE, and TL, we deduced a schematic diagram of the energy level and discussed the mechanism of PSL of the phosphors. As Dy3+ dopant increases, the Eu2+, Dy3+ co-doped phosphors not only generate more defects of V O •• and V Sr ʺ, but also introduce Dy Sr • defect with proper trap depth, meanwhile, a thermally assisted tunneling mechanism will gradually dominate during the persistent luminescence, which is responsible for that the phosphor with x = 0.02, y = 0.01 presents the best long afterglow property. [ABSTRACT FROM AUTHOR]

Multi-modal strategies for optical information storage have received a lot of attention to meet the increasing security requirements. In this case, long persistent luminescence (LPL) phosphors with different dopant ions were obtained by introducing Dy3+ and Ho3+ ions into the BaSi 2 O 5 :Eu2+ phosphor to adjust the distribution and depth of the trap centers. The generation of the pure phase BaSi 2 O 5 was confirmed by X-ray diffraction (XRD) and XRD Rietveld refinement. The peak emission of BaSi 2 O 5 : Eu2+ phosphor is about 500 nm with 313 nm excitation. Both BaSi 2 O 5 : Eu2+, Dy3+, and BaSi 2 O 5 : Eu2+, Ho3+ phosphors exhibit emission characteristics of Eu2+ ions. The trap depths of the three phosphors are different by Gaussian fitting of thermoluminescence (TL) curves, and the depth of BaSi 2 O 5 : Eu2+, Dy3+ phosphor can reach 1.070 eV. Typically, the flexible luminescent film based on BaSi 2 O 5 : Eu2+ phosphor can be written optical pattern using 365 nm ultraviolet (UV) light, such as "DL" and "fireworks" patterns, and subsequently read out by thermal or infrared light stimulus. Further, a strategy for encryption and decryption of dynamic optical information in Morse code has been developed using BaSi 2 O 5 : Eu2+, BaSi 2 O 5 : Eu2+, Dy3+, and BaSi 2 O 5 : Eu2+, Ho3+ phosphors, indicating the prospective use in optical information security. [ABSTRACT FROM AUTHOR]

The construction of anatase/rutile heterojunctions in TiO2 is an effective way of improving the CO2 photoreduction activity. Yet, the origin of the superior photocatalytic performance is still unclear. To solve this issue, the band edges between anatase and rutile phases were theoretically determined based on the three-phase atomic model of (112)A/II/(101)R, and simultaneously the CO2 reduction processes were meticulously investigated. Our calculations show that photogenerated holes can move readily from anatase to rutile via the thin intermediated II phase, while photoelectrons flowing in the opposite direction may be impeded due to the electron trapping sites at the II phase. However, the large potential drop across the anatase/rutile interface and the strong built-in electric field can provide an effective driving force for photoelectrons' migration to anatase. In addition, the II phase can better enhance the solar light utilization of (112)A/(100)II, including a wide light response range and an intensive optical absorption coefficient. Meanwhile, the mixed-phase TiO2 possesses negligible hydrogenation energy (CO2 to COOH*) and lower rate-limiting energy (HCOOH* to HCO*), which greatly facilitate CH3OH generation. The efficient charge separation, strengthened light absorption, and facile CO2 reduction successfully demonstrate that the anatase/rutile mixed-phase TiO2 is an efficient photocatalyst utilized for CO2 conversion. [ABSTRACT FROM AUTHOR]

X-ray excited radioluminescence was demonstrated in Pr-doped lithium niobate polycrystalline samples with varying lithium-to-niobium ratios (R LN). The samples' phase structures, excitation and emission spectra, and radioluminescence were experimentally analyzed to investigate the tuning effects of R LN. Theoretical calculations based on Density Functional Theory (DFT) were conducted to elucidate the underlying mechanisms, and thermoluminescence curves were measured to verify the predictions of the theoretical analysis. We suggest that both photoluminescence and radioluminescence properties can be effectively tailored by adjusting the crystal structure, as well as the depth and density of electron traps within the LiNbO 3 :Pr matrix through R LN modulation. This research contributes to the development and practical implementation of scintillation materials derived from rare-earth-doped lithium niobate. [ABSTRACT FROM AUTHOR]

The frequency characteristics of impedance, phase difference between current and voltage, hodographs, and corresponding equivalent circuits of Fe nanofilms grown in a constant magnetic field on Gd2O3 and silicate glass substrates are investigated. It is shown that with increasing magnetic field strength from 40 E to 1200 E, the morphology of Fe films changes from labyrinthine to continuous, consisting of coalesced iron islands. This complex morphology of the films is the source of the induction and capacitance components of the imaginary part of the impedance. It was found that at a frequency of 630 Hz, a consistent electrical resonance is observed in Fe films, as well as a minimum value of the total impedance. At frequencies above 104 Hz, a sharp change in the impedance components and phase difference is observed in Fe films, which is probably due to the peculiarities of the film morphology. The Nyquist hodographs were constructed and the parameters of the corresponding equivalent circuits were calculated using the ZView computer program. It is shown that both the equivalent schemes of the hodographs and the peculiarities of the frequency dependence of the impedance and phase difference components depend largely on the morphology of the films, which is determined by the elasticity of the magnetic field applied during their growth, as well as by the chemical composition of the substrates. Gd2O3 substrates affect Fe films due to the d-f exchange interaction between the unfilled f and d electron shells of the atoms that make up the Gd2O3 and Fe layers. Silicate glass has an effect due to the ions of technological impurities contained in its composition, which can act as traps for electrons passing through the Fe film. [ABSTRACT FROM AUTHOR]

Crystallinity and crystal structure greatly influence the photocatalytic behavior of photocatalysts. Pristine g-C3N4 produced by traditional thermal-induced polycondensation reaction bears low crystallinity and thus poor photoactivity, which originates from the incomplete polymerization of the precursor containing amine groups, abundant hydrogen bonds, and unreacted amino, as well as cyanide functional groups in the skeleton. During photocatalytic process, these residual functional groups often work as electron trap sites, which may hinder the transfer of electrons on the plane, resulting in low photoactivity. Fortunately, crystalline carbon nitride (CCN) was reported as a promising photocatalyst because its increased crystallinity not only reduces the number of carriers recombination centers, but also increases charge conductivity and improves light utilization due to extended π-conjugated systems and delocalized π-electrons. As such, we summarize the recent studies on CCN-based photocatalysts for the photoactivity enhancement. Firstly, the unique structure and properties of CCN materials are presented. Next, the preparation methods and modification strategies are well outlined. We also sum up the applications of CCN-based materials in the environmental purification and energy fields. Finally, this review concerning CNN materials ends with prospects and challenges in the obtainment of high crystallinity by effective techniques, and the deep understanding of photocatalytic mechanism. [ABSTRACT FROM AUTHOR]

Enhancement of the light-absorption response and utilization of the photogenerated carriers represent a robust strategy for the design of high-performance photocatalyst. In this work, grafting CoxP nanoclusters onto S-scheme heterojunction of W18O49/ZnIn2S4 (WO/ZIS-CoxP) with strong response to the ultraviolet–visible–near infrared ray (UV–vis–NIR) region has been achieved, which possesses efficient electron-transfer-channel, and boosts charge-separation and transport kinetics. The as-prepared WO/ZIS-CoxP yields an impressive solar-driven hydrogen production rate of 45 mmol·g−1·h−1. The increased photocatalytic performance is attributed to the synergistic effect of the composite catalyst: (1) The local surface plasmon resonance-induced "hot electron" injection of W18O49 significantly increases the electron density; (2) the engineered S-scheme directional electron transfer promotes charge separation and enhances the reducing capability of photoexcited electrons; and (3) CoxP as electron-trap site for accelerating surface proton reduction reaction. This work provides a platform to impart nonprecious co-catalyst for engineering S-scheme heterojunction, serving a class of efficient solar-driven photocatalyst towards hydrogen production. [ABSTRACT FROM AUTHOR]