High Figure Of Merit Value Research Articles

Probing the opto-electronic, phonon spectrum, and thermoelectric properties of lead-free fluoride perovskites A2GeSnF6 (A = K, Rb, Cs) for energy harvesting devices

The present work employs density functional theory to explore the structural, optoelectronic, and thermoelectric attributes of the halide-based double perovskite A2GeSnF6 (A = K, Rb, and Cs) compounds. The stable phonon dispersion spectrum affirms dynamical stability, whereas the enthalpy of formation and tolerance factor evaluated collectively verify structural stability. Considering the Tran Blaha modified Becke Johnson potentials (mBJ), the predicted direct band gaps along the symmetry point are 3.19 eV for K2GeSnF6, 3.16 eV for Rb2GeSnF6 and 3.12 eV Cs2GeSnF6. According to an in-depth examination of the optoelectronic features, A2GeSnF6 (A = K, Rb, and Cs), double perovskites are assuring contenders for optoelectronic devices due to their suitable bandgap. The extremely high figure of merit values (0.94–0.97) obtained from the numerical calculation of power factor and thermal conductivity suggest the intriguing prospects of these compositions for thermoelectric devices. These studies offer a perceptive comprehension of the materials for their potential applications in the future.

Mathematical analysis of the solar assisted thermoelectric generator

The direct conversion of solar energy into electrical energy is primarily dependent on the photovoltaic systems. However, in the last few decades, researchers have shown interest to work on the thermoelectric modules for direct conversion of solar thermal energy into electrical energy based on the Seebeck effect. This research paper provides a comprehensive analysis of various Solar Thermoelectric Generator (STEG) designs, focusing on their conversion efficiencies. Despite the comparatively lower efficiency of STEG in comparison to photovoltaic (PV) cells, owing to limitations in the figure of merit value and temperature differences between hot and cold sides of the thermoelectric modules, this study proposes strategies for enhancement. Approaches include the development of materials with higher figure of merit values, design optimization, solar tracking, heat storage systems, and efficient heat sink designs. Also, Mathematical analysis of the power and efficiency calculation of a STEG has been presented on the basis of some fundamental and derived mathematical equations. The overall efficiency of STEG, a product of Opto-thermal Efficiency and thermoelectric module efficiency, is explored, identifying an optimal hot side temperature for maximum efficiency. Module mismatch analyses for series and parallel connections are also derived, underscoring conditions for mitigating power loss. These findings serve as guidelines for designing more feasible and efficient STEG systems, with considerations for economic viability, sustainability and greenhouse gas reduction throughout the life cycle.

Evaluation of 8-bit eDRAM by varying the aspect ratio of the in-cell transistors

Embedded dynamic random-access memories (eDRAM) are widely used in the design of embedded systems for the safeguard of information during their operation. However, since these memories are installed in the same chip as the host system, it is crucial to consider their dimensioning. For this reason, in our work, the aspect ratio width and length (W/L) of complementary metal oxide semiconductor (CMOS) transistors inside 3-transistor logic cells (3T) is diversified to evaluate the effect on electrical behavior with area optimization through the figure of merit (FoM): power consumption-delay product of 8-bit memories with an operating frequency of 8.3 MHz, varying the aspect ratio of transistors inside the cell have been obtained 8.6f as lowest and 152.3f as highest FoM values. Those storage devices have been developed on 0.00085 mm2 using a 180-nm CMOS technology.

Optimization of the "Perth CT" Protocol for Preoperative Planning and Postoperative Evaluation in Total Knee Arthroplasty.

Background and Objectives: Total knee arthroplasty (TKA) has become the treatment of choice for advanced osteoarthritis. The aim of this paper was to show the possibilities of optimizing the Perth CT protocol, which is highly effective for preoperative planning and postoperative assessment of alignment. Materials and Methods: The cross-sectional study comprised 16 patients for preoperative planning or postoperative evaluation of TKA. All patients were examined with the standard and optimized Perth CT protocol using advance techniques, including automatic exposure control (AEC), iterative image reconstruction (IR), as well as a single-energy projection-based metal artifact reduction algorithm for eliminating prosthesis artifacts. The effective radiation dose (E) was determined based on the dose report. Imaging quality is determined according to subjective and objective (values of signal to noise ratio (SdNR) and figure of merit (FOM)) criteria. Results: The effective radiation dose with the optimized protocol was significantly lower compared to the standard protocol (p < 0.001), while in patients with the knee prosthesis, E increased significantly less with the optimized protocol compared to the standard protocol. No significant difference was observed in the subjective evaluation of image quality between protocols (p > 0.05). Analyzing the objective criteria for image quality optimized protocols resulted in lower SdNR values and higher FOM values. No significant difference of image quality was determined using the SdNR and FOM as per the specified protocols and parts of extremities, and for the presence of prothesis. Conclusions: Retrospecting the ALARA ('As Low As Reasonably Achievable') principles, it is possible to optimize the Perth CT protocol by reducing the kV and mAs values and by changing the collimation and increasing the pitch factor. Advanced IR techniques were used in both protocols, and AEC was used in the optimized protocol. The effective dose of radiation can be reduced five times, and the image quality will be satisfactory.

Millisecond-Response Nematic Liquid Crystal for Augmented Reality Displays

Developing fast-response liquid crystals (LCs) is an essential way to achieve low cost, high resolution, and good visual experience for augmented reality (AR) displays. In this paper, we optimized one new nematic LC mixture SNUP01 to meet the requirements of fast-response phase-only liquid crystal on silicon (LCoS) devices in AR displays. The photoelectric performance of this new LC mixture and three commercial LC mixtures were further comparatively evaluated, and the 2π phase-change response speed of this new LC mixture was extrapolated. The research results indicate that SNUP01 possesses high birefringence, moderate dielectric anisotropy, low viscoelastic coefficient, low activation energy, and high figure of merit values. When using this LC mixture at 25 °C @ λ = 633 nm, a 2π phase change can be achieved at 5 V with a total response time of up to millisecond response. Widespread applications of this LC mixture for AR displays are foreseeable.

Performance analysis of OTFT-based SRAM topologies

In terms of mechanical flexibility, organic SRAM offers better designs and a commercially feasible option with the ability to deliver acceptable performance. This paper investigates the implementation of different SRAM topologies based on organic thin film transistors (OTFTs). In this work, a compact spice model is used to simulate pOTFT and nOTFT in LTSpice software. Time delays, power consumption, the power delay product (PDP), and static noise margin (SNM) for read and write operations are calculated, and a comparative analysis of OTFT based 6T, 7T, 8T, and 9T SRAM topologies is performed. Among different topologies, 9T OTFT SRAM cell achieves a 1.67× increase in SNM, compared to conventional 6T OTFT-based SRAM cell. The highest figure of merit value of 9T SRAM cell indicates its suitability for various applications.

Amplification and Dynamic Control of Circularly Polarized Luminescence in Poly (vinyl Alcohol)/CdSe@CdS Nanorod Assembly Twisted‐Stacking Hetero‐Structures

AbstractChiroptical materials with strong and switchable circularly polarized luminescence (CPL) properties have gained considerable interest due to their feasible applications in optoelectronic devices, sensing, and information encryption. However, in most cases, their luminescence dissymmetry factor (glum) and figure of merit (FOM) values remain very low. Herein, a novel heterogeneous twisted‐stacking structure is proposed, which endows with strong CPL amplification (a maximum of ≈15‐fold enhancement) over traditional homogeneous structures and a high FOM value up to 0.11. Interestingly, their CPL performance (including the sign, magnitude, and spectral position) and the FOM values can be precisely manipulated or even inversed by simply uniaxial stretching, since the phase retardation of the anisotropic poly (vinyl alcohol) layer can be controlled. Moreover, by combining with the viologen gel electrochromic system, the in situ voltage‐driven switching and patterning of the CPL signal can be successfully achieved, with low operation voltage and good cycling stability. This study provides a creative strategy for fabricating strong and electrical switchable CPL‐active materials, which promise new opportunities in miniaturized smart electrochiroptical devices for future information technology.

Thermoelectric properties of SiC nanocomposite Mg2Si0.4Sn0.6 with Sb doping prepared by vacuum induction levitation melting and spark plasma sintering

The SiC nanocomposite Mg2(Si0·4Sn0.6)Sb0.015/(y)SiC (0 ≤ y ≤ 0.01) with Sb doping were prepared using the vacuum induction levitation melting technique in conjunction with mechanical alloying and spark plasma sintering process. The microstructure and thermoelectric properties were systematically investigated. The hierarchical nanostructures for the samples are composed of point defects, SiC nanocomposite particles, coherent in-situ nanophases, and grains. The SiC nanocomposite cause a minor reduction in electrical performance, and the constructed hierarchical nanostructures significantly decreased the lattice thermal conductivities. The highest figure of merit value of 1.55 is obtained at 643 K for the y = 0.0075 SiC nanocomposite sample.

Enhanced thermoelectric properties of n-type CoSb3-based composites by incorporating In particles

Thermoelectric devices that consist of N-and P-type TE legs in series have been well known and applied owing to the ability that could convert waste heat into electric energy. Among them, skutterudite materials have been frequently studied as the main object because they are environmentally friendly and inexpensive. In this study, N-type CoSb3-based materials were synthesized using a low-temperature synthesis method and spark plasma sintering. Those thermoelectric matrix that incorporated Indium (In) particles were prepared via manual grinding method. The thermoelectric properties, microstructures, and morphologies of the pure and In-doped Co0.91Ni0.09Sb3 samples were systematically evaluated. A maximum power factor value of 3642.3 μW/mK2 was obtained at 723 K for a Co0.91Ni0.09Sb3/1 wt%In sample and the highest figure of merit value of 1.01 was attained for a Co0.91Ni0.09Sb3/2 wt%In sample. These results indicate that Indium particles as secondary phase can improve the thermoelectric performance of N-type CoSb3-based materials.

First principles study on structural, mechanical, and thermoelectric properties of half-Heusler alloy (KLiTe)

In this study, the structural, optoelectronics, elastic, and transport properties of KLiTe were estimated from first principles computations using the FP-LAPW technique and semi-classical Boltzmann transport theory The exchange–correlation is addressed employing the generalized gradient approximation with Perdew-Burke-Ernzerhof scheme (GGA-PBE). In order to distinguish between the brittle and ductile properties, the Poisson and Pugh's ratio was calculated. The semiconductor KLiTe is demonstrated to have a direct band gap. The compound under investigation exhibits significant Seebeck coefficient and power factor values. The high-power factor of 8.3 × 1011 W/K2ms. that KLiTe exhibits at 1200 K makes it a potentially viable material for thermoelectric applications. Due to their high figure of merit values, the results obtained indicate that KLiTe could be a strong contender for thermoelectric generator applications at low and moderate temperature.

Guided-mode resonance sensors with ultrahigh bulk sensitivity and figure of merit assisted by a metallic layer and structural symmetry-breaking.

We propose a refractive index sensor with both high bulk sensitivity and figure of merit (FOM) that engages the guided-mode resonance (GMR) effect with the assistance of a metallic layer and structural symmetry-breaking in the grating layer. Owing to the existence of the metallic layer, the electric field at resonance can be reflected to the sensing environment, and enhanced bulk sensitivity is realized. Meanwhile, the full width at half maximum of the GMR mode can be decreased by increasing the asymmetrical degree of the grating, thus obtaining a high FOM which benefits the sensing resolution. A bulk refractive index sensitivity of 1076.7 nm/RIU and an FOM up to 35889 RIU-1 are achieved simultaneously. Other structural parameters such as the refractive index and fill factor of the grating are systematically discussed to optimize the sensing performance. The proposed GMR sensor with both high bulk sensitivity and FOM value has potential uses in applications with more stringent sensing requirements.

Optimization of Processing Steps for Superior Functional Properties of (Ba, Ca)(Zr, Ti)O3 Ceramics.

Lead-free piezoelectric ceramics with nominal composition at morphotropic phase boundary Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCTZ) prepared by different processing routes and sintered either by conventional solid-state reaction or by spark plasma sintering (SPS) techniques were comparatively investigated to observe the role of structural modifications and of microstructures on the dielectric, ferroelectric, piezoelectric and electrocaloric responses. The ceramics presented relative densities from 75% to 97% and showed variations in their phase composition as a result of variable mixing and different synthesis and sintering parameters providing local compositional heterogeneity. As result, all of the ceramics showed diffuse phase transition and ferroelectric switching responses, with parameters affected mostly by density (Pr between 3.6 to 10.1 μC/cm2). High values for the electrocaloric response in the Curie range were found for the ceramics with predominantly orthorhombic character. Field-induced structural modifications were probed by tunability anomalies and by XRD experiments in remanence conditions. Piezoelectric effects with notably high figure of merit values were assigned to the better densification and poling efficiency of BCTZ ceramics.

Insight into the electronic structure, magnetic, and thermoelectric properties of transition metal pnictides KCr2L2 (K= Ca, Sr; L = P, As): As substitute source for renewing energy

In this study, we have investigated the electronic structure, magnetic and thermoelectric properties of the antiferromagnetic (A-AFM) phase for ternary KCr2L2 (K= Ca, Sr; L = P, As) compounds using the framework of full-potential augmented plane wave method within the generalized gradient (PBE-GGA) approximations. We determined that the presence of the A-AFM phase is more favorable among the possible spin phases at their relaxed lattice parameters. Based on the stable phase, we found that both Cr atoms are well modulated in AFM phase. Furthermore, we have investigated the thermoelectric properties for all investigated compounds from 50 K to 800 K. Our calculations suggest the SrCr2As2 and SrCr2P2 compound can obtain high figure of merit values ∼1 with optimized carrier concentration at lower temperature, indicating the strontium based compounds are promising candidate for low-temperature thermoelectric device. In all, our calculations discover the novel ternary KCr2L2 (K= Ca, Sr; L = P, As) compounds with promising physical properties for potential spintronics and magnetic application.

Indium-free flexible perovskite solar cells with AZO/Cu/Ag/AZO multilayer transparent electrodes

Flexible perovskite solar cells (PSCs) fabricated on plastic substrates have great potential applications in numerous emerging fields such as portable/wearable electronics, automobiles, and flying objects due to their high efficiency, low cost, and light weight. However, most of the reported flexible PSCs based on plastic substrate use expensive and fragile ITO as transparent electrodes, resulting in significant performance degradation after continuous bending. Here, we develop an indium-free AZO/Cu/Ag/AZO multilayer transparent electrode deposited on PET by magnetron sputtering technique and utilize it to fabricate of flexible PSCs. It is demonstrated that predepositing an ultrathin Cu layer on the AZO layer can significantly reduce the permeation threshold of the subsequent grown Ag layer, thereby improving the optoelectronic properties of the deposited multilayer transparent electrode. The highest figure of merit value of 3.8 × 10−2 Ω−1 was obtained for the AZO(40 nm)/Cu(0.1 nm)/Ag(7 nm)/AZO (40 nm) electrode, which has an average relative optical transmittance in the visible light range (400–800 nm) of 90.77 % and sheet resistance of 9.9 Ω/sq. The flexible PSCs based on the optimized AZO/Cu/Ag/AZO electrode achieve power conversion efficiency (PCE) of 14.68 %. Moreover, they can maintain 90 % of the initial PCE even after 5000 bending cycles at a bending radius of 8 mm.

D-Shaped Fiber Surface Plasmon Resonance Refractive Index Sensor Enhanced By MXene (Ti3C2Tx)

A D-shaped fiber-optic surface plasmon resonance (SPR) sensor with MXene (Ti3C2Tx) is proposed as the sensing enhancement material. A spin coating method was used to cover the gold film D-shaped fiber SPR sensor with a layer of MXene. Experimentally, the sensor's sensitivity, full width at half maximum (FWHM), and figure of merit (FOM) are discussed. The effect of various MXene concentrations on D-shaped fiber SPR sensors was investigated. The results demonstrate that as the MXene concentration increases, the sensitivity, FWHM, and FOM value of the D-shaped fiber SPR sensor increase as well. The MXene-based D-shaped fiber SPR sensor exhibits the highest sensitivity, measuring 3143 nm/RIU, and the highest FOM value, 15.26. Compared to the Au-film D-shaped fiber SPR sensor, Sensitivity is increased by 53.6%. The results indicate that MXene could be used to enhance the performance of SPR refractive index sensors.

Enhanced Thermoelectric Efficiency of Cement-Based Materials with Cuprous Oxide for Sustainable Buildings

The thermoelectric effect of plain cement paste is usually weak. To improve the thermoelectric performance of cement composites, functional components, such as carbon fibers, steel fibers, carbon nanotubes, and graphene, are often added to cement paste. In view of the advantage of metal oxides with a higher band gap, pure cuprous oxide crystals with different particle sizes were synthesized by a hydrothermal method and incorporated into the cement matrix to improve the thermoelectric efficiency of cement composites in this study. Pure cuprous oxide crystals with different particle sizes (15 μm, 1.5 μm, and 100 nm) were prepared by controlling the reaction temperature and time, pH value, amount of reducing agent, and polyvinylpyrrolidone in the reaction system. The Seebeck coefficient, electrical conductivity, and thermal conductivity of the cement composites with 5.0 wt.% nanostructured Cu2O powder increased to 3966 ± 54 μV/K, (2.68 ± 0.12) × 10−4 S/m, and 0.69 ± 0.007 W/(m·K), respectively. Thereby, a high figure of merit value of 1.93 × 10−6 was obtained for the cement composites, which made future application of cement composites in energy harvesting for buildings possible.

Antimonene, CNT and MoS2 Based SPR-Fiber-Optic Probe for Tuberculosis Detection

In this work, two–dimensional (2D) materials-based surface plasmon resonance assisted fiber sensor is designed to detect the tuberculosis (TB) disease. Transfer matrix method (TMM) that includes characteristic matrix is applied to compute the reflection coefficient and transmitted power of normal and tuberculosis infected sample. Probe design is made up of multimode fiber core, polymer clad, silver (Ag) as plasmonic metal, and 2D material and analyte. Three 2D materials such as carbon-nanotube (CNT), MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , and antimonene are explored to detect TB infection. The impact of introducing the CNT, MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , and antimonene on the output of sensor is discussed in detail. The maximum figure of merit (FOM) and sensitivity values with probe-1, probe-2, and probe-3 are 95.23 RIU <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> , 88.23 RIU <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> and 117.64 RIU <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> and 15000 nm/RIU, 20,000 nm/RIU, 20,000 nm/RIU, respectively. Sensitivity and FOM increases with an increase in refractive index (RI) of the TB sample with probe 2 and probe 3 design. In the case of probe 1 employing MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> as 2D material, sensitivity and FOM increase first, reaches a maximum, and then decrease with an increase in RI. The proposed 2D materials based SPR fiber sensor with probe-3 design provides high FOM and sensitivity value makes it suitable platform to detect TB in the range of 1.343 RIU- 1.351 RIU.

Solvent effect on the optoelectronic properties of fluorine doped SnO2 thin films prepared by spray-pyrolysis

This work explores the effects of choice of solvent on the optoelectronic properties of spray-pyrolyzed fluorine (F)-doped tin oxide (SnO2) thin films deposited on glass substrates over an area of 5 × 5 cm2. A 2-methoxyethanol (C3H8O2) and ethylene glycol (C2H6O2) admixture in varying proportions is used as solvent. The volume of C2H6O2 is varied as 0, 25, 50, and 100 ml in the above admixture. The XRD patterns reveal successful formation of tetragonal SnO2 lattice without any structural change. Upon changing the volume of C2H6O2 in C3H8O2, the textured growth changes from (110) direction to (211) direction. The film thickness is found to vary significantly with varying volume of the mixed solvents. Transmittance is found to increase and reach a maximum value of 75% (at 550 nm) for the film deposited with only C2H6O2. The photoluminescence emission data reveals that the overall intensity of violet emission is found to quench upon increasing the volume of C2H6O2. The sheet resistance is found to decrease gradually with increasing volume of C3H8O2 and is found to be the lowest with a value of 6.34 Ω/□ for complete 100 ml of C3H8O2. The surface wettability nature of the thin films obtained from contact angle measurements indicate changeover from hydrophobic to hydrophilic nature (104.4° to 52.2°) with increasing C2H6O2 vol in the admixed solvent. Among all these samples, the film prepared with 100% C2H6O2 solvent shows highest figure of merit value of 3.02×10–3 Ω–1. The optimal film prepared with complete C2H6O2 solvent has surface work function of 4.69 eV and shows highest power conversion efficiency of 2.21% when used in a dye-sensitized solar cell compared to devices fabricated using other admixed solvents. In the solvent admixture, higher volume of C3H8O2 is beneficial for obtaining low sheet resistance, whereas higher volume of C2H6O2 leads to high transmittance, thereby permitting to fix the solvent concentration based on the need for optical transparency and electrical sheet resistance as per custom requirements for a specific optoelectronic application.

Anharmonic effects on lattice dynamics and thermal transport of two-dimensional InTe monolayer

The lattice thermal conductivity (κl) plays a key role in the performance of thermoelectric (TE) materials, where the lower values lead to higher figure of merit values. Two-dimensional (2D) group III-VI monolayers such as InTe are promising materials for TE energy generation owing to their low κl that lead to high TE figure of merit values. In this work, we investigate the influence of the lattice anharmonicity on the lattice thermal conductivity of InTe monolayer. The thermodynamic parameters are calculated by using the self-consistent phonon (SCP) theory. The κl value of the InTe monolayer is obtained to be 0.30 Wm−1 K−1 by using the standard Boltzmann transport equation (BTE) approach, while it is 3.58 Wm−1 K−1 by using SCP + BTE approach. These results confirm the importance of the anharmonic effects on the κl value, where it was found to be significantly higher (91%) using the SCP + BTE approach than that obtained using the standard BTE approach.

First‐principles investigation of Rb2Ag(Ga/In)Br6 for thermoelectric and photovoltaic applications

AbstractIn this article, we have systematically investigated the structural, electronic, optical and thermoelectric properties of Rb2Ag(Ga/In)Br6. The resulting negative formation energy along with the absence of imaginary phonon modes confirm the thermodynamic stability of Rb2Ag(Ga/In)Br6. In addition, the derived electronic properties by using GGA‐PBE + mBJ + SOC functional show that the direct band gap values are 1.21 eV and 1.42 eV for Rb2AgGaBr6 and Rb2AgInBr6, respectively. Furthermore, the dispersed direct band nature of Rb2Ag(Ga/In)Br6 leads to their outshining optical properties such as higher order (105 cm−1) absorption coefficient, appreciable optical conductivity, and low reflectivity. Moreover, the higher figure of merit values of Rb2Ag(Ga/In)Br6 are resulted from their ultra‐low thermal conductivity and high electrical conductivity. Thus, Rb2Ag(Ga/In)Br6 are predicted to be potential photovoltaic and thermoelectric materials.