Energy Loss Research Articles

Correlation of Dimer-Linker-Induced Conformational Lock with Nonradiative Energy Loss in Organic Solar Cells

Correlation of Dimer-Linker-Induced Conformational Lock with Nonradiative Energy Loss in Organic Solar Cells

Spatially resolved random telegraph fluctuations of a single trap at the Si/SiO2 interface

We use electrostatic force microscopy to spatially resolve random telegraph noise at the Si/SiO2 interface. Our measurements demonstrate that two-state fluctuations are localized at interfacial traps, with bias-dependent rates and amplitudes. These two-level systems lead to correlated carrier number and mobility fluctuations with a range of characteristic timescales; taken together as an ensemble, they give rise to a [Formula: see text] power spectral trend. Such individual defect fluctuations at the Si/SiO2 interface impair the performance and reliability of nanoscale semiconductor devices and will be a significant source of noise in semiconductor-based quantum sensors and computers. The fluctuations measured here are associated with a four-fold competition of rates, including slow two-state switching on the order of seconds and, in one state, fast switching on the order of nanoseconds which is associated with energy loss.

Energy management strategy for extended range electric logistics vehicle based on type-2 fuzzy control

To overcome the limitations of fuzzy energy management strategy (EMS) in describing uncertainty, this paper proposes an EMS based on type-2 fuzzy (T2F), which optimizes energy consumption for extended range electric logistics vehicle (ERELV). Firstly, establish an energy consumption simulation model for ERELV. Then, an EMS based on T2F controller is designed. The strategy takes the state of charge (SOC) and the demand power as the input, and the range extender power as the output. This paper analyses the influence of T2F control strategy on the energy consumption of the ERELV, and uses the model-based design method to verify the EMS in the Hardware-in-the-loop (HIL) simulation test. The test results show that compared with the traditional fuzzy control strategy, the T2F strategy can reduce the engine’s energy loss by 12.58%. Finally, actual fuel consumption tests were conducted on the established ERELV model. By comparing the results of C-WTVC and CHTC-HT operating conditions, the model was verified to meet the research requirements of EMSs in this paper and has practical significance.

Near-Infrared Unimolecular Chemiluminescence Probes for Deep-Tissue Imaging.

Chemiluminescence (CL) imaging has emerged as a promising optical imaging technique due to minimal background autofluorescence and being excitation-free. However, the emission of most chemiluminescent probes was concentrated in the visible light region, which limited the tissue penetration. Although some NIR chemiluminescence probes have been reported based on the chemiluminescence resonance energy transfer (CRET) strategy, the energy loss was inevitable. Thus, it is crucial to develop near-infrared (NIR) unimolecular probes with direct chemiluminescence. Herein, we propose a strategy of increasing conjugation for designing and synthesizing novel NIR chemiluminescence unimolecular probes that consist of luminol, electron acceptor, π-bridge, and electron donor. Luminol was conjugated to the unimolecular backbone to produce direct NIR chemiluminescence. Notably, the direct CL mechanism of probes was investigated. Compared with CRET-based chemiluminescence, this direct CL was more advantageous to immediately convert the chemical energy into chemiluminescence, avoiding energy degradation. Furthermore, the corresponding nanoparticles with great biosafety were prepared by self-assembly with amphiphilic DSPE-PEG. Especially, TTBL@PEG-NPs with NIR-I emission were successfully used in the sensitive in vivo chemiluminescence imaging of various inflammation models, such as peritonitis, ear swelling, and colitis. This study paves the way for the design of NIR unimolecular chemiluminescence probes and deep-tissue imaging.

Comprehensive evaluation of mechanical properties, optoelectronic features, photovoltaic performance, and crystal stability of Ba3MX3 (M = As, Sb; X = Cl, Br, I)

Herein, the first-principles computations are utilized to study the optoelectronic properties, photovoltaic performance, crystal stability, and mechanical features of Ba3MX3 (M = As, Sb; X = Cl, Br, I). Through comprehensive structural stability evaluation, all compounds are determined to be stable. The results indicate that Ba3MX3 (M = As, Sb; X = Cl, Br) is brittle while both Ba3AsI3 and Ba3SbI3 are ductile. The HSE06-based electronic structure calculations show that the direct-gap nature is revealed for six compounds, and the energy band gaps are within the range of 1.35–1.65 eV. The fundamental band gap can be modulated by virtue of X-anion substitution. The low carrier effective masses are disclosed for these compounds. Their optical features exhibit that high solar absorption and weak reflectance and energy loss are observed. Ultimately, an ultra-high theoretical conversion efficiency of 31.9 % is implemented for Ba3MI3 (M = As, Sb). Besides, the remaining four compounds also have high conversion efficiencies within 29–30 %. From the suitability for practical applications, both Ba3AsI3 and Ba3SbI3 are chosen as the best candidates for the absorber layers of effective single-junction solar cells. Our findings unveil the suitability of these inorganic materials for optoelectronic applications.

Initial results from neoclassical tearing mode stabilization experiment in KSTAR high normalized beta plasmas

Abstract Active stabilization of neoclassical tearing modes (NTMs) is critical for high beta plasma operation in the KSTAR tokamak. In recent device operation, an experiment was conducted to develop a m/n = 2/1 NTM stabilization in high normalized beta (βN) plasmas having βN > 3 by using electron cyclotron current drive (ECCD). The experiment is designed to first demonstrate the direct mode stabilization effect of the device EC system by varying the ECCD deposition location around the mode rational surface to prepare for future NTM stabilization in KSTAR using feedback schemes. In the experiment, the toroidal magnetic field strength, BT, is reduced to 1.5–1.6 T to create a highly localized ECCD profile on a large island width expected to produce a high stabilization effect. To align the ECCD with the mode, BT is varied between discharges by keeping the EC wave injection angles fixed to move the current deposition location across the q = 2 mode rational surface in ~1 cm steps along the plasma midplane. The result shows a prompt reduction of the mode amplitude by ~60% with a partial recovery of the loss of stored energy when the ECCD with 0.7 MW power is applied promptly after the mode onset at BT = 1.54 T. This abrupt reduction of the mode amplitude is significantly weaker or disappears in other discharges having slightly different BT in which the ECCD is deposited a few centimeters away. This result indicates a direct interaction between the driven EC current and the radially localized island structure first observed in the device. The EC ray-tracing analysis using the TORAY code shows that the applied EC-driven current aligns with the mode rational surface when the mode amplitude is observed to decrease. The stability of the observed 2/1 NTM is examined by constructing the modified Rutherford equation (MRE). The calculated EC power requirement for complete mode stabilization by assuming perfect alignment of ECCD on the mode is 0.8-1.7 MW by considering the uncertainties in the equation. This MRE-computed mode stability agrees with the experiment. The result projects that the present KSTAR EC system can stabilize the 2/1 NTM disrupting high βN plasmas, and provides the requirement of the mode-ECCD alignment for complete mode stabilization in future experiments in which an accurate alignment is planned to be made by feedback schemes being developed.

Performance assessment of a 30.26 kW grid-connected photovoltaic plant in Egypt

Abstract This paper presents an experimental analysis and performance evaluation of a grid-connected photovoltaic plant installed on the rooftop of the Electronics Research Institute in Cairo, Egypt. Cairo is classified as a hot-desert climate region according to the standard Koppen-Geiger climate classification system. Over a year, we monitored real-time data to assess key system performance metrics, such as energy yield, efficiencies, performance ratio, capacity factor, and losses. Based on the obtained experimental results, the highest final yield of 5.2498 hr/day was observed in the summer, whereas the lowest yield of 3.439 hr/day occurred in the winter months. The photovoltaic plant had an average annual system efficiency of 15.8%, while the photovoltaic and inverter had mean yearly efficiencies of 17.1% and 97.2%, respectively. The average annual performance ratio is 83.03%, and the capacity factor is 18.72%. The monthly total loss exhibited a linear rise alongside increasing ambient temperature and solar irradiance. The ambient temperature affected the system efficiency, photovoltaic efficiency, and performance ratio. The findings can help strengthen forecasts of future large-scale photovoltaic plants in hot desert climates. Moreover, they can guide the design, optimization, operation, and maintenance of new grid-connected photovoltaic systems.

Significance of the proton energy loss mechanism to gold nanoparticles in proton therapy: a Geant4 simulation

The biological effectiveness in proton therapy is only slightly greater than of the treatment by X-ray and hence, many researches have suggested the use of gold nanoparticles for increasing the ionization interactions to produce more secondary electrons and elevate the yield of DNA damage. But the ionization interactions also lead to protons energy loss inside the nanoparticles. The present study shows that, the protons slowed-down by High-Z nanoparticles are responsible for dose enhancement rather than the produced secondary electrons. To this purpose, using Geant4 Monte Carlo tool, one million nanoparticles distributed in a proton irradiated volume and variation of the proton’s spectra and the dose related to this variation has been demonstrated. It was found that, the elevation in proton’s LET values when passing through the gold nanoparticles will lead to a more significant dose enhancement than the increased dose due to the extra secondary electrons. Also, it was found that, the mechanism of protons slowing-down by gold nanoparticles has another useful aspect in proton therapy in which, the dose leakage to surrounding healthy tissues will be reduced which must be considered in future investigations more precisely.

Designing a Highly Crystalline Polymer Donor with Alkylsilyl and Fluorine Substitution to Achieve Efficient Ternary Organic Solar Cells.

Adopting a ternary strategy is an effective approach to enhance the power conversion efficiency (PCE) in organic solar cells (OSCs). Previous research on highly efficient ternary systems has predominantly focused on those based on highly crystalline dual small molecule acceptors. However, limited attention has been given to ternary systems utilizing dual polymer donors. Herein, by incorporating the fluorine and alkylsilyl substitution, a new polymer donor named PX1 is developed, which demonstrates strong crystallinity and excellent miscibility with polymer PM6. Moreover, PX1 broadens and enhances the absorption properties of the PM6:L8-BO blends, and its molecular orbital energy level is situated between those of PM6 and L8-BO, highlighting its suitability as a third component. Introducing 20% PX1 into the PM6:L8-BO system resulted in a high PCE of 18.82%. PX1 effectively suppresses charge recombination and reduces energy losses, while also serving as a morphology modulator that enhances the crystallization and improves the molecular packing order of the active layer by shortening the π-π stacking distance and extending crystalline coherence length. These factors collectively contribute to the performance improvements in ternary devices. This study demonstrates that employing a dual polymer donor strategy is a promising approach for achieving high-performance ternary OSCs.

Understanding the pressure effect on the physical properties of half-Heusler semiconductor LiCaX (X = As, Sb, N) compounds from Ab-initio calculations

The study delves into the structural, elastic, electronic, thermodynamic, and lattice dynamical and optic properties of LiCaX (X = As, Sb, N) ternary half-Heusler compounds under varying pressure and temperature conditions. Employing density functional theory with the generalized gradient approximation (GGA) in VASP codes, the initial steps involve optimizing the structure of the compound (cubic MgAgAs-type, space group F43m, C1b), determining elastic constants (C11, C12, and C44), and calculating elastic moduli (bulk modulus, shear modulus, Young's modulus). Other mechanical parameters such as Pugh's ratio, Poisson's ratio, and Zener anisotropy factor are also derived, providing insights into the brittle/ductile characteristics and isotropic/anisotropic behavior. The study further explores different vibrational modes in the compounds, and the effects of pressure on elastic anisotropy, vibrational, and optical properties are thoroughly investigated. Utilizing the quasi-harmonic Debye model, the research successfully reports V/Vo, bulk modulus, thermal expansion coefficient, and heat capacity at constant volume over a temperature range from 0 to 1000 K. The variation of photon energy is analyzed concerning the real and imaginary parts of the dielectric constant, refractive indices, extinction coefficient, reflectivity, and energy loss function up to 20 eV. The findings encapsulate the fundamental physical properties of all considered compounds, concluding with suggestions for potential future research avenues.

Study on Phase Change Materials’ Heat Transfer Characteristics of Medium Temperature Solar Energy Collection System

Within the next five years, renewable energy is expected to account for approximately 80% of the new global power generation capacity, with solar power contributing to more than half of this growth. However, the intermittent nature of solar energy remains a significant challenge to fully realizing its potential. Thus, efficient energy storage is crucial for optimizing the effectiveness and dependability of renewable energy. Phase-change materials (PCMs) can play an important role in solar energy storage due to their low cost and high volumetric energy storage density. The low thermal conductivity of PCMs restricts their use for energy storage, despite their immense potential. Hence, the primary goal of this study is to experimentally investigate the energy storage capacity of two blended phase-change materials (paraffin and barium hydroxide octahydrate) through integration with a medium-temperature solar heat collection system. The experimental findings reveal that the blended PCMs possess the highest cumulative charge fraction (0.59), energy capacity, and low energy loss compared to each PCM alone. Furthermore, the phase change storage tank achieves higher heat storage (27%) and exergy storage efficiency (18%) compared to the stored tank water without any PCMs. The blended PCMs enhanced their performance, exhibiting improved interaction and excellent thermal storage properties across a range of temperatures, offering an opportunity for the design of an energy-efficient, low-cost storage system.

Dynamic response characteristics of proton exchange membrane fuel cell during transient loading: An experiment study

The dynamic performance of Proton Exchange Membrane Fuel Cell (PEMFC) is crucial for safe and efficient operation and remains a major barrier to commercialization. In this paper the dynamic response characteristics of PEMFC under serpentine flow field (SFF) and parallel flow field (PFF) are discussed. The effects of current loading, operating pressures, anode and cathode stoichiometric ratios, as well as operating temperatures on the dynamic response characteristics of PEMFC are systematically studied through experimental methods. Furthermore, the principle and mitigation strategies for voltage undershoot are investigated. It shows that lower current density, higher back pressure and higher temperature are benefit to alleviate voltage undershoot. Compared with the SFF, the Second-stage time delay of PFF is shortened by 9.2 s, the VU is decreased by 17.27 mV, and the energy loss is reduced by 0.71%. Moreover, Pearson correlation coefficient is proposed to evaluate the correlation between index and PEMFC performance.

A Simple Model of the Radio–Infrared Correlation Depending on Gas Surface Density and Redshift

We introduce a simple parametric model of the radio–infrared correlation (i.e., the ratio between the IR luminosity and the 1.4 GHz radio luminosity, q IR) by considering the energy loss rate of high-energy cosmic-ray (CR) electrons governed by radiative cooling (synchrotron, bremsstrahlung, inverse Compton scattering), ionization, and adiabatic expansion. Each process of CR electron energy loss is explicitly computed and compared to each other. We rewrite the energy loss rate of each process to be dependent on the gas surface density and redshift using the relevant scaling relations. By combining each energy loss rate, the fraction of the synchrotron energy loss rate is computed as a function of gas surface density and redshift and used to extrapolate the well-established “local” radio–infrared correlation to the high-redshift Universe. The locally established q IR is reformulated to be dependent upon the redshift and the gas surface density and applied for understanding the observed distribution of the radio–infrared correlation of high-redshift galaxies in I. Delvecchio et al. Our model predicts that the q IR value is anticorrelated with gas surface density and the redshift dependency of the q IR value changes by the gas surface density of galaxies, which captures the observed trend of q IR values for stellar-mass-selected star-forming galaxies with a minimal impact of radio–infrared selection bias.

Establishing Non-stoichiometric Ti4O7 Assisted Asymmetrical C-C Coupling for Highly Energy-Efficient Electroreduction of Carbon Monoxide.

Exploring an appropriate support material for Cu-based electrocatalyst is conducive for stably producing multi-carbon chemicals from electroreduction of carbon monoxide. However, the insufficient metal-support adaptability and low conductivity of the support would hinder the C-C coupling capacity and energy efficiency. Herein, non-stoichiometric Ti4O7 was incorporated into Cu electrocatalysts (Cu-Ti4O7), and served as a highly conductive and stable support for highly energy-efficient electrochemical conversion of CO. The abundant oxygen vacancies originated from ordered lattice defects in Ti4O7 facilitate the water dissociation and the CO adsorption to accelerate the hydrogenation to *COH. The highly adaptable metal-support interface of Cu-Ti4O7 enables a direct asymmetrical C-C coupling between *CO on Cu and *COH on Ti4O7, which significantly lowers the reaction energy barrier for C2+ products formation. Additionally, the excellent electroconductivity of Ti4O7 benefits the reaction charge transfer through robust Cu/Ti4O7 interface for minimizing the energy loss. Thus, the optimized 20Cu-Ti4O7 catalyst exhibits an impressive selectivity of 96.4% and ultrahigh energy efficiency of 45.1% for multi-carbon products, along with a remarkable partial current density of 432.6 mA cm-2. Our study underscores a novel C-C coupling strategy between Cu and the support material, advancing the development of Cu-supported catalysts for highly efficient electroreduction of carbon monoxide.

Nonadiabatic dynamical simulations to the radiative recombination of nonfullerene acceptor molecular excited states

Improving the radiative recombination rate of nonfullerene acceptor (NFA) molecular excited states can help to promote their photoluminescence quantum yield and thus reduce the nonradiative energy loss in NFA-based organic solar cells. In this Letter, by developing a nonadiabatic dynamical simulation method, we clarify quantitative correlations of some typical characteristics of NFA molecules with their radiative recombination rates. For a single NFA molecule, the weakening of electron−phonon coupling and the strengthening of electron-push−pull potential can each improve the radiative recombination rate. For different NFA molecular aggregates, their radiative recombination rates are all reduced compared with a single molecule, where the A-to-A and A-to-D type J-aggregates have higher rates than D-to-D type H-aggregate. To further improve the radiative recombination rate of NFA molecular J-aggregates, we should increase the intermolecular distance, such as extending the side chain length.

Depth profiling of implanted D in silicates: Contribution of solar wind protons to water in the Moon and terrestrial planets

The solar wind protons implanted in silicate material and combined with oxygen are considered crucial for forming OH/H O on the Moon and other airless bodies. This process may also have contributed to hydrogen delivery to planetary interiors through the accretion of micrometre-sized dust and planetesimals during early stages of the Solar System. This paper experimentally investigates the depth distribution of solar wind protons in silicate materials and explores the mechanisms that influence this profile. We simulated solar wind irradiation by implanting 3 keV D ions in three typical silicates (olivine, pyroxene, and plagioclase) at a fluence of sim 1.4 × 10 ions/cm . Fourier transform infrared spectroscopy was used to analyse chemical bond changes, while transmission electron microscopy (TEM) characterised microstructural modifications. Nanoscale secondary ion mass spectrometry (NanoSIMS) was employed to measure the D/ O ratio and determine the depth distribution of implanted deuterium. The newly produced OD band (at 2400–2800 cm –1 ) in the infrared spectrum reveals the formation of O–D bonds in the irradiated silicates. The TEM and NanoSIMS results suggest that over 73<!PCT!> of the implanted D accumulated in fully amorphous rims with a depth of 70 nm, while 25<!PCT!> extended inwards to sim 190 nanometres, resulting in partial amorphisation. The distribution of these deuterium particles is governed by the collision processes of the implanted particles, which involve factors such as initial energy loss, cascade collisions, and channelling effects. Furthermore, up to 2<!PCT!> of the total implanted D penetrated the intact lattice via diffusion, reaching depths ranging from hundreds of nanometres to several micrometres. Our results suggest that implanted solar wind protons can be retained in silicate interiors, which may significantly affect the hydrogen isotopic composition in extraterrestrial samples and imply an important source of hydrogen during the formation of terrestrial planets.

Simulation-based design: minimizing energy consumption in residential buildings through optimal thermal insulation

Purpose This study aims to optimize the energy consumption of residential buildings in mild and humid climates. It investigates the use of thermal insulation to reduce thermal load through energy simulation analysis. Design/methodology/approach A residential building located in Rasht city, Iran (a mild and humid climate zone), is simulated using DesignBuilder software. Subsequently, the minimum thermal resistance for external walls and roof is analyzed along with its impact on building energy consumption and carbon emissions. Findings The simulation results indicated a 26.5% reduction in heat loss through the walls and a 14.2% reduction through the roof due to optimal thermal insulation. Furthermore, optimal insulation led to a 19.2% reduction in cooling system energy use, a 12% reduction in heating system energy use and a combined 15.3% reduction in total energy consumption for cooling and heating. Originality/value This optimization process leads to several benefits: reduced costs associated with thermal and cooling energy losses in buildings, improved building performance against atmospheric factors and, ultimately, a reduction in energy consumption across the building industry. This research can be valuable to various stakeholders, including the construction industry and building sector, municipalities and engineering systems, building owners and contractors and environmental organizations. By implementing these findings, they can improve the state of modern building insulation and achieve greater energy efficiency.

Interface-resolved photovoltage generation dynamics and band structure evolution in a PbS quantum dot solar cell.

For directed development of solar cells using nanomaterials such as quantum dots, there is a need to understand the device function in detail. Understanding where photovoltage is generated in a device and where energy losses occur is a key aspect of this, and development of methods which can provide this information is needed. We have previously shown that time-resolved photoelectron spectroscopy of core levels can be used to follow the photovoltage dynamics at a specific interface of a lead sulfide quantum dot solar cell. Here, we use the method's selectivity and sample design to investigate the photovoltage generation in different parts of this solar cell and determine how the different layers (including the absorber layer thickness) contribute to charge separation. We show that all layers contribute to photovoltage generation and that a gold contact deposited on the quantum dots is necessary for full photovoltage generation and slow charge recombination. By combining the information obtained, we are able to experimentally follow the time evolution of the solar cell band structure during the charge separation process. Furthermore, we can identify which specific layers need to be optimized for an overall improvement of quantum dot cells. In the future, this methodology can be applied to other types of devices to provide insights into photovoltage generation mechanisms.

Establishing Non‐stoichiometric Ti4O7 Assisted Asymmetrical C‐C Coupling for Highly Energy‐Efficient Electroreduction of Carbon Monoxide

Exploring an appropriate support material for Cu‐based electrocatalyst is conducive for stably producing multi‐carbon chemicals from electroreduction of carbon monoxide. However, the insufficient metal‐support adaptability and low conductivity of the support would hinder the C‐C coupling capacity and energy efficiency. Herein, non‐stoichiometric Ti4O7 was incorporated into Cu electrocatalysts (Cu‐Ti4O7), and served as a highly conductive and stable support for highly energy‐efficient electrochemical conversion of CO. The abundant oxygen vacancies originated from ordered lattice defects in Ti4O7 facilitate the water dissociation and the CO adsorption to accelerate the hydrogenation to *COH. The highly adaptable metal‐support interface of Cu‐Ti4O7 enables a direct asymmetrical C‐C coupling between *CO on Cu and *COH on Ti4O7, which significantly lowers the reaction energy barrier for C2+ products formation. Additionally, the excellent electroconductivity of Ti4O7 benefits the reaction charge transfer through robust Cu/Ti4O7 interface for minimizing the energy loss. Thus, the optimized 20Cu‐Ti4O7 catalyst exhibits an impressive selectivity of 96.4% and ultrahigh energy efficiency of 45.1% for multi‐carbon products, along with a remarkable partial current density of 432.6 mA cm‐2. Our study underscores a novel C‐C coupling strategy between Cu and the support material, advancing the development of Cu‐supported catalysts for highly efficient electroreduction of carbon monoxide.

A study of optical properties and electron energy loss spectra of ZnS by linear response theory

The linear response theory has been applied to study the optical properties and electron energy loss spectra of ZnS. The ground state is built using the Full-Potential Linearized Augmented Plane Wave method. Thereafter, the electronic properties such as band structure and density of states are calculated. Calculations of electron energy loss spectra and optical properties are performed on the top of these ground state electronic properties. The calculations are performed using three exchange–correlation kernels namely, adiabatic local density approximation, long range contribution, and the bootstrap. The random phase approximation is also considered. An approach proposed by us to find the material dependent parameter α is used in long range contribution kernel to capture more accurate optical properties. Three values of α viz 0.78, 1.09, and 1.22 are considered. It is observed that the α = 0.78 gives very good results. This proposed scheme is found to work very well for ZnS also. The effect of local field and electron–hole interaction on the spectra is examined. For example after incorporating local field effect the high frequency dielectric constant ε∞ [i.e. ε1E→0eV ], reduces by 9.19, 12.26, 13.51 and 11.02% for random phase approximation, adiabatic local density approximation, long range contribution and bootstrap kernel respectively. In EELS plasmon peak positions are found using the three kernels and random phase approximation. A good accord with experimental results is noted after incorporating local field effects. It is observed that local field effect causes redshift of prominent peak (i.e. plasmon peak) in electron energy loss spectra by 0.61 eV.