Low Energy Loss Research Articles

Toluene Processed All‐Polymer Solar Cells with 18% Efficiency and Enhanced Stability Enabled by Solid Additive: Comparison Between Sequential‐Processing and Blend‐Casting

The emergence of polymerized small molecule acceptors (PSMAs) has significantly improved the performance of all‐polymer solar cells (all‐PSCs). However, the pace of device engineering lacks behind that of materials development, so that a majority of the PSMAs have not fulfilled their potentials. Furthermore, most high‐performance all‐PSCs rely on the use of chloroform as the processing solvent. For instance, the recent high‐performance PSMA, named PJ1‐γ, with high LUMO, and HOMO levels, could only achieve a PCE of 16.1% with a high‐energy‐level donor (JD40) using chloroform. Herein, we present a methodology combining sequential processing (SqP) with the addition of 0.5%wt PC71BM as a solid additive (SA) to achieve an impressive efficiency of 18.0% for all‐PSCs processed from toluene, an aromatic hydrocarbon solvent. Compared to the conventional blend‐casting (BC) method whose best efficiency (16.7%) could only be achieved using chloroform, the SqP method significantly boosted the device efficiency using toluene as the processing solvent. In addition, the donor we employ is the classic PM6 that has deeper energy levels than JD40, which provides low energy loss for the device. We compare the results with another PSMA (PYF‐T‐o) with the same method. Finally, an improved photostability of the SqP devices with the incorporation of SA is demonstrated.

Energy storage and ferroelectric properties of flexible 1-x(Na0.5Bi0.5TiO3)-xBaTiO3 thin films on Pt/mica substrates

We investigated the energy storage and ferroelectric properties of flexible 1-x(Na0.5Bi0.5TiO3)-xBaTiO3 (NBT) thin films with BaTiO3 (BT) concentrations ranging from 0 to 6 mol% on Pt/mica substrates depending on the BT concentration. The NBT thin films exhibiting preferentially a-oriented crystallinity on the (111) Pt/mica substrates showed improved leakage current characteristics by increasing the BT concentration. In particular, the NBT thin films with zero BT concentration showed a high remanent polarization of about 28.4 μC/cm2. On the other hand, the NBT thin films with a BT concentration of 6 mol% significantly reduced the remanent polarization to about 4.7 μC/cm2 due to the characteristics of the relaxor. As a result, the NBT thin films with a BT concentration of 6 mol% showed a high energy storage efficiency of 89.5 % with a high recoverable energy storage density of 54.3 J/cm3 and a low loss energy density of 6.3 J/cm3.

Orchestrating the impact of antisites and vacancy defects on the elastic and optoelectronic properties of boron arsenide.

Cubic boron arsenide (c-BAs), a semiconducting material with ultra-high thermal conductivity and carrier mobilities, has been studied using first-principles calculation. This study examined the elastic and optoelectronic properties of c-BAs. The challenge of subphase boron (B) formation in bulk form owing to the volatile nature of arsenic (As) makes it mandatory to calculate its optoelectronic properties, by producing vacancies and antisite defects with BAs (As atom on a B site) and AsB (B atom on an As site). The mechanical properties including bulk (B), shear (G) moduli, and Poison's ratio of all the systems were studied. It was found that mechanical instability of the structure is observed for the overall vacancy creation, arsenic substitution, and mutual antisite defects. Further, pristine c-BAs showed an indirect bandgap of 1.48eV. Defect formation reduces the bandgap and shifts the absorption peaks, which improves the overall optoelectronic properties of the host material. In addition, B vacancy formation shows the maximum optical absorption and reflectivity and low energy loss, suggesting its potential applications for optoelectronic devices. The obtained anticipated data from this study is for the optoelectronic and elastic properties of c-BAs, for the device applications in photonics and electronics. In this paper, the elastic and optoelectronic properties of the pristine and defected c-BAs were systematically investigated using the Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA). The SIESTA program uses pseudopotentials in the norm-conserving nonlocal forms and pseudo-atomic orbital (PAO) basis set with a double-zeta potential (DZP) which are fundamental for calculating the Hamiltonian and overlap matrices in O(N) operations.

Halide homogenization for low energy loss in 2-eV-bandgap perovskites and increased efficiency in all-perovskite triple-junction solar cells

Halide homogenization for low energy loss in 2-eV-bandgap perovskites and increased efficiency in all-perovskite triple-junction solar cells

Approach toward Low Energy Loss in Symmetrical Nonfullerene Acceptor Molecules Inspired by Insertion of Different π-Spacers for Developing Efficient Organic Solar Cells.

In this quantum approach, by adding bridge/π-spacer fragments between the donor and acceptor parts of a newly constructed DF-PCIC (A-D-A type) molecule, it is the aim to improve the photovoltaic characteristics of organic solar cells (OSCs). After π-spacer insertion into the reference molecule (DF-R), six new molecules (DF-M1 to DF-M6) were designed. The optoelectronic attributes of newly inspected molecules were theoretically calculated using MPW1PW91/6-31G(d,p) level of theory. All newly proposed molecules possessed a lower band gap (Eg), a higher value of absorption, lower reorganization energy, greater dipole moment, and lower energies of excitations than the DF-R molecule. The frontier molecular orbital study proclaimed that the DF-M1 molecule has the lowest band gap of 1.62 eV in comparison to the 2.41 eV value of DF-R. Absorption properties represented that DF-M1 and DF-M2 molecules show the highest absorption values of up to 1006 and 1004 nm, respectively, in the near-infrared region. Regarding the reorganization energy, DF-M2 has the lowest value of λe (0.0683896 eV) and the lowest value of λh (0.1566471 eV). DF-M2 and DF-M5 manifested greater dipole moments with the values of 5.514665 and 7.143434 D, respectively. The open circuit voltage (VOC) of all the acceptors was calculated with J61, a donor complex. DF-M4 and DF-M6 molecules showed higher values of VOC and fill factor than the DF-R molecule. Based on the given results, it was supposed that all the newly presented molecules might prove themselves to be better than the reference and thus might be of great interest to experimentalists. Thus, they are suggested to be used to develop proficient OSC devices with improved photovoltaic prospects in the near future.

Experimental Studies of Hydrodynamic and Energy Characteristics of a High-Voltage Electrochemical Explosion in Limited Liquid Volumes

In this paper, the dependence of the charging voltage, stored electrical energy, and the mass of the combusted exothermic mixture on electrical, energy and hydrodynamic characteristics of a high-voltage electrochemical explosion (HVEE) in limited volumes of liquid on is experimentally studied. A comparison with other methods of initiating an electric discharge under similar conditions was made. The results established that the HVEE makes it possible to carry out a high-voltage electric discharge with low energy losses (less than 9%) and to realize an electrical breakdown mode close to aperiodic. It has been found that HVEE can generate pressure waves with an amplitude up to 37% and a pulse up to 45% larger (at a charging voltage of 25 kV or higher) than that of an electric explosion of an initiating metallic conductor of optimum length under the same initial conditions. It was found that an increase in the charging voltage leads to an increase in the amplitude and pulse of the generated pressure wave along a linear dependence. A compre-hensive analysis of the dependences of the energy and hydrodynamic characteristics showed that the main influence on the formation of the pressure wave pulse during the HVEE is provided by both the stored electrical energy and the interconnection between the electrical parameters of the discharge circuit and the mass of the burning exothermic mixture, which determines the shape of the discharge characteristics.

Research on high frequency reliability of silicon carbide MOSFETs resonant circuit

Silicon carbide MOSFETs could process high power at high switching frequency with little loss. The driving circuit produce loss, which is proportional to the switching frequency. Resonant gate driving circuit, which has a inductor to produce resonant with a parasitic capacitor to recycle energy is used to reduce energy loss in the high frequency situation. Firstly, this paper introduces the simplest resonant gate driver. After that, three different types of resonant gate driver with their similar versions are introduced. In these optimized circuits, the third resonant gate driver (RGD3) is the simplest to control and has the lower energy loss, but the second resonant gate driver (RGD2) has faster switching speed and the first resonant gate driver (RGD1) provides more loops to energy feedback.

November 2023 Imaging Case of the Month: A Crazy Association

No abstract available. Manuscript truncated after 150 words. HPI: A 55-year-old man presents with a history of cough, poor appetite, low energy, and weight loss over the previous 6-10 months following COVID-19 infection 2 months earlier. PMH, SH, FH: The patient’s past medical history was positive for CVOID-19 infection 2 months earlier as well as pneumonia, not specified, in the previous year. The patient’s past medical history was also remarkable for a 7-unit gastrointestinal hemorrhage approximately one year earlier following polypectomy for benign lesions in the transverse colon. During that hospital admission a complete blood count showed 1% blasts which prompted hematology consultation. The consulting oncologist felt the peripheral blasts were the result of a leukemoid reaction secondary to increased bone marrow stimulation owing to the patient’s acute anemia caused by the gastrointestinal hemorrhage. Macrocytosis and reticulocytosis was also noted and attributed to the same. Repeat complete blood count showed no blasts although some myelocytes, metamyelocytes, and polychromasia …

Numerical analysis of an ultralow switching loss IGBT with super junction and blocking junction

In order to reduce the switching loss (ESW) and enhance the breakdown voltage (BV), in this paper, an insulated gate bipolar transistor with an internal blocking junction and super junction (SJBJ-IGBT) is proposed and investigated. By inserting P-pillar and N-pillar on both sides of the drift region, a drift area with auxiliary depletion function can be formed. The junction of the primary blocking layer (JPB) is located internally in the device’s drift region. The JPB is reverse biased and withstand the main E-field during device turn-off. Meanwhile, the JPB is surrounded by P-pillar and N-pillar, reducing the E-field(E-field) peak value of device, and making E-field distribution more uniform. Furthermore, during device turn-on, the reduction of the effective area of drift region makes it easier for the JPB side of the P-drift region to accumulate excess holes. So that the SJBJ-IGBT is easier to turn-on. The snapback phenomenon of SJBJ-IGBT is eliminated. Simulation results demonstrate that, under the same forward conduction voltage (VON) condition, the proposed device exhibits a significantly lower turn-on energy loss (EON) compared to the traditional super junction(SJ-IGBT), and is 44.5% lower than that of IPBJ-IGBT, while their turn-off energy losses (EOFF) are almost equivalent.Besides, the optimized E-field distribution in the SJBJ-IGBT shows 13.2% improvement of BV. Researching results can provide important reference for reducing the ESW of IGBT.

Enhanced high-temperature energy storage properties in BNT-based ceramics with well-controlled low dielectric loss

High-temperature resistance is one of the hot topics in the development of high-power density dielectric materials. It is still a great challenge for dielectric materials to meet the requirements of high energy density and low energy loss at high temperature. Based on the philosophy of increasing the Curie temperature and decreasing the dielectric loss at high temperature, a ceramic system of (1-x)Bi0.5Na0.5TiO3-xBi(Mg0.3Zr0.6)O3 ((1-x)BNT-xBMZ) is designed to improve the high-temperature energy storage properties. The Curie temperature was significantly increased from 320 °C to nearly 400 °C, and the dielectric loss was controlled below 5% up to 400 °C in the 0.92BNT-0.08BMZ ceramic. Due to the high Curie temperature and low dielectric loss, the maximum polarization and discharge energy density at 200 °C under 200 kV/cm of the 0.92BNT-0.08BMZ ceramic sample are as high as 48.79 μC/cm2 and 3.73 J/cm3, respectively. With the BMZ content increases, the changing rate of Pmax in the temperature range of 30∼200 °C decreases from 18.76% for the x = 0.06 ceramic to 10.27% for the x = 0.10 ceramic under 120 kV/cm, and the remanent polarization decreases from 5.23 μC/cm2 to 2.55 μC/cm2 at 200 °C, correspondingly. All these characteristics show that (1-x)BNT-xBMZ ceramics have broad application prospects in the field of high-temperature energy storage systems.

Impact of alkaline-earth doping on the mechanical, electronic, optical and photocatalytic properties of CsPb0.875AE0.125Br3 (AE = Be, Mg, Ca, Sr and Ba): Insights from DFT perspective

Density functional theory was used to examine the stability, mechanical properties, photoelectric properties, and photocatalytic performance of the inorganic perovskite CsPbBr3 (AE = Be, Mg, Ca, Sr, and Ba) in order to enhance its properties and lessen the presence of lead. The predicted band gap values (1.31–2.06 eV) were quite close to the optimal band gap for photoelectric conversion. Additionally, CsPb0.875Sr0.125Br3 has effective electron and hole masses that are significantly lower than those of CsPbBr3 in its original form, making it a better candidate for carrier transport. All CsPb0.875AE0.125Br3 materials are mechanically stable and exhibit favorable all-around characteristics. And it has a lower energy loss function and reflectivity in the visible light spectrum, which helps the conversion efficiency. According to the sideband potential and variances in the hole and electron effective masses, CsPb0.875Ca0.125Br3, CsPb0.875Sr0.125Br3, and CsPb0.875Ba0.125Br3 all have a tremendous potential for improving photocatalytic performance and converting solar energy into chemical energy.

Unveiling Oxygen K-Edge and Cobalt L-Edge Electron Energy Loss Spectra of Cobalt Hydroxide and Their Evolution under Electron Beam Irradiation.

Cobalt hydroxides, Co(OH)2, have attracted considerable attention due to their diverse applications in the fields of energy and the environment. However, probing the electronic structure of Co(OH)2 is challenging, mainly due to its sensitivity to electron beam irradiation. In this study, we report the unperturbed O K-edge and Co L-edge for Co(OH)2 by electron beam damage and investigate the electronic structure transformation of Co(OH)2 under electron beam irradiation, using low current electron energy loss spectroscopy. In particular, the O K-edge pre-peak at 530 eV, which is not found in the undamaged Co(OH)2, begins to appear with an increasing electron beam current. In addition, the Co L-edge peak shifts to a higher energy, close to Co3O4, indicating that the localized phase transition within Co(OH)2 leads to the formation of Co3O4.

An Approach Towards Low Energy Loss by End-capped Modification of A2–D–A1–D–A2-type Molecules for Tuning the Photovoltaic Properties of Organic Solar Cells

In this project, the study is focused on the substitution at determined sites of reference molecule (R) to enhance optoelectronic properties, which might affect the photovoltaic performance of organic solar cells. Herein, seven new molecules (M1 to M7) were designed by the modification of the terminal acceptors. The density functional theory was employed to explore optoelectronic properties. Majority of the molecules own exceptional optical properties than reference molecule, for instance, narrow bandgap, low excitation energy, lower binding energies, better oscillator strength and progressive light harvesting efficiency. The density of state, frontier molecular orbitals and transition density matrix diagrams indicated that the charge density transfer occurs from donor to acceptor. Moreover, charge transfer investigations of designed molecules with PTB7-Th complex were performed by analyzing the concentration of charge transfer over molecular orbitals, i.e., highest occupied to lowest unoccupied molecular orbitals. Thus, these computed molecules may be employed to develop efficient organic solar cell devices with promising photovoltaic prospects in the near future.

A computational insight into the Zintl SZr2N2 and BaAg2S2 phases for optoelectronic thermoelectric applications

The physical characteristics of SZr2N2 and BaAg2S2 Zintl phases have been explored by utilizing the full-potential augmented plane wave (FP-LAPW) method with the combination of modified Becke-Johnson (mBJ) approximation. The negative formation energies and phonon modes with positive frequencies endorsed the stability of both compounds. The electronic band profile reveals a bandgap of 1.18 eV for SZr2N2 and 2.15 eV for BaAg2S2. The optical characteristics are also calculated. The absorption of light for the studied compounds falls in the ultra-violet region, which shows their possibility to be employed as UV-rays absorbers. A large optical conductivity and low energy loss is also seen for both materials on UV region. The efficiency of temperature-dependent thermoelectric properties increases with the temperature rise, as calculated with the BoltzTraP code. The high electrical with low thermal conductivities and maximum Seebeck coefficient is witnessed for both materials. The large ZT values of 0.75 and 0.80 are achieved for SZr2N2 and BaAg2S2, respectively. All calculated transport parameters indicate the opportunity of using the studied compounds for thermoelectric applications.

On-chip multifunctional self-configurable quadrilateral MZI network

Photonic integrated circuits have garnered significant attention in recent years. To enhance the functional versatility of these devices, researchers have introduced the concept of reconfiguration into photonic integrated circuits. Inspired by field programmable gate arrays in the electrical domain, programmable photonic chips employing various topologies have been developed. However, users still encounter challenges when utilizing these devices, as they need to understand the internal structure and principles of the chip and individually adjust the tunable basic units within the topology network. In this paper, we employ the quadrilateral topological network based on the on-chip Mach–Zehnder interferometer as a black box to realize a highly self-reconfigurable optical signal processor. By leveraging this approach, we achieve positive real-valued matrix computation, optical routing, and low-loss optical energy splitting. Our demonstration effectively showcases the immense potential of on-chip programmable photonic waveguide meshes.

Topologies and modulation methods in leakage current suppression for PV grid-tied inverters

Photovoltaic (PV) inverters are widely discussed as solar energy became commonly used as a renewable energy source. Transformerless grid-tied inverters are often chose for their low cost and low energy loss. Since the existence of stray capacitance between PV cells and conducting surface causes a changing common-mode voltage (CMV) which would arise leakage current and thus pollute the output current quality to the grid and endanger human safety, novel topologies and modulation strategies are proposed to save the problem for transformerless inverters. In this paper, different methods to suppress the leakage current will be analysed. The theoretical analysis of CMV and leakage current generation by single-phase inverter is presented. Based on the basic principle of leakage current suppression topologies proposed to eliminate the leakage current are introduced. The effects of some well-known modulation methods on CMV controlling have been compared, and novel methods dealing with three-phase harmonic management are presented.

Study on water entry characteristics of the projectile colliding with the floating ice based on fluid-structure interaction method: Dynamic response and energy conversion

This study investigates the water entry process of the collision between the ocean detector and the floating ice in polar environments, which is crucial for detecting polar ocean energy. The study utilizes the fluid-structure interaction (FSI) method to analyze the dynamic characteristics of the projectile colliding with the floating ice and the energy change between objects. The effect of the size, structure, and distribution of the floating ice on the water entry process is also taken into account. Experiments have verified the accuracy of the FSI method. The presence of floating ice alters the cavity evolution and subsequently affects the water entry state of the projectile. The width of the floating ice also has a noticeable effect on the cavity evolution during collision water entry. Smaller floating ice sizes result in lower kinetic energy loss after the projectile collides with the floating ice. As the mass of the floating ice increases, the elastic strain energy generated by the projectile when it first collides with the floating ice increases. After the collision separation, the elastic strain energy generated by the second collision is also greater. Additionally, stress concentration occurs during the collision, and the hydrodynamic force on the object is influenced by the evolution of the cavity. When the projectile collides with the edges of the floating ice on both sides, a unique spherical splash crown is formed. This collision mode results in a lower loss of kinetic energy and elastic strain energy compared to colliding with single floating ice.

Mesoscopic trap and elastic properties of polyetherimide nanocomposites with improved energy storage performance

Polymer nanocomposites (PNCs) are important energy storage dielectrics for capacitors. However, the lack of quantitative research on the properties of mesoscopic scale conductivity, traps, and Young's modulus in interfacial regions between polyetherimide and nanofillers results in an unclear understanding of the relation between the structure and properties. Polyetherimide/Al2O3 PNCs are prepared by in-situ polymerization, and the dielectric, thermal, and mechanical properties are measured. The experiments show that the film doped with 3 wt% nanofillers has the highest resistivity, Young's modulus, breakdown strength, and energy storage density. Then, the mesoscale distributions of the conductivity and Young's modulus in interfacial regions are solved as the inversion problem of electric and stress fields, and the macroscopic conductivity and Young's modulus of PNCs are obtained by high-throughput simulations. The conductivity, trap, and Young's modulus distributions are obtained by comparing the simulation and experimental results. It shows that the molecular chains in interfacial regions are bounded by nanofillers to form a tighter aggregated structure, hindering the molecular motion. Accordingly, the charge transport between molecular chains slows down, the trap energy increases and the conductivity decreases. The tighter aggregated structure makes PNCs have higher breakdown strength, energy storage density, and lower energy loss.

Semi-embedded slot waveguide electro-optic modulator.

Electro-optic modulators are essential devices on silicon photonic chips in modern optical communication networks. This paper presents a compact, low-loss electro-optic modulator. The modulation efficiency is greatly improved by embedding the lower half of the slot waveguide into the buried oxide layer and inserting graphene at the junction. The interaction of graphene with an optical field in a waveguide is studied using the finite element method. The functions of phase modulation and absorption modulation are realized by changing the gate voltage to change the chemical potential of graphene. The semi-embedded slot waveguide optical modulator has a length of 50µm. After simulation verification, it can be used as an electro-absorption modulator and can achieve a modulation depth of 26.38dB and an insertion loss of 0.60dB. When used as an electro-refractive modulator, it can be realized with a linear change of phase from zero to π; the total insertion loss is only 0.59dB. The modulator has a modulation bandwidth of 79.6GHz, and the energy consumption as electro-absorption and electro-refraction modulation are 0.51 and 1.92pj/bit, respectively. Compared with common electro-optic modulators, the electro-optic modulator designed in this paper has a higher modulation effect and also takes into account the advantages of low insertion loss and low energy consumption. This research is helpful for the design of higher-performance optical communication network devices.

Stochastic Multi-Objective Scheduling of a Hybrid System in a Distribution Network Using a Mathematical Optimization Algorithm Considering Generation and Demand Uncertainties

In this paper, stochastic scheduling of a hybrid system (HS) composed of a photovoltaic (PV) array and wind turbines incorporated with a battery storage (HPV/WT/Batt) system in the distribution network was proposed to minimize energy losses, the voltage profile, and the HS cost, and to improve reliability in shape of the energy-not-supplied (ENS) index, considering energy-source generation and network demand uncertainties through the unscented transformation (UT). An improved escaping-bird search algorithm (IEBSA), based on the escape operator from the local optimal, was employed to identify the optimal location of the HS in the network in addition to the optimal quantity of PV panels, wind turbines, and batteries. The deterministic results for three configurations of HPV/WT/Batt, PV/Batt, and WT/Batt were presented, and the results indicate that the HPV/WT/Batt system is the optimal configuration with lower energy losses, voltage deviation, energy not supplied, and a lower HS energy cost than the other configurations. Deterministic scheduling according to the optimal configuration reduced energy losses, ENS, and voltage fluctuation by 33.09%, 53.56%, and 63.02%, respectively, compared to the base network. In addition, the results demonstrated that the integration of battery storage into the HPV/WT enhanced the various objectives. In addition, the superiority of IEBSA over several well-known algorithms was proved in terms of obtaining a faster convergence, better objective value, and lower HS costs. In addition, the stochastic scheduling results based on the UT revealed that the uncertainties increase the power losses, voltage deviations, ENS, and HPV/WT/Batt cost by 2.23%, 5.03%, 2.20%, and 1.91%, respectively, when compared to the deterministic scheduling.