Power Factor Values Research Articles

Unusual Transport and Impact of Nonparabolic Electronic Band Structure on the Thermoelectric Performance in n‐Type In4Se3‐Based Thermoelectric Materials

Unusual thermoelectric (TE) transport in n‐type In4Se3 has been reported in the context of first‐principles electronic structure calculation and Boltzmann transport theory. The density of states (DOS) shows certain peaks due to a nontopological Mexican hat and parabolic capping around the edges of Kane bands. The effect of such hard shifts of bands shows anomalously high Seebeck coefficient (S = 550 μV K−1 at ≈1017 cm−3) at room temperature due to very slow decreasing S and rapidly increasing DOS effective mass with carrier concentration compared to that obtained from Kane and parabolic band model. The best TE performance is predicated in Kane transport region (≈1018 cm−3) over the wide range of temperature, 300–700 K. The calculated values of relaxation time (≈10−14 s at 660 K), electrical conductivity, power factor and figure of merit in iodine‐doped sample and those obtained from the rigid band model of pure sample show excellent agreement with the reported experimental results.

Nanostructured Thermoelectric PbTe Thin Films with Ag Addition Deposited by Femtosecond Pulsed Laser Ablation

Pulsed laser deposition operated by an ultra-short laser beam was used to grow in a vacuum and at room temperature natively nanostructured thin films of lead telluride (PbTe) for thermoelectric applications. Different percentages of silver (Ag), from 0.5 to 20% of nominal concentration, were added to PbTe deposited on polished technical alumina substrates using a multi-target system. The surface morphology and chemical composition were analyzed by Scanning Electron Microscope and X-ray Photoelectron Spectroscopy, whereas the structural characteristics were investigated by X-ray Diffraction. Electrical resistivity as a function of the sample temperature was measured by the four-point probe method by highlighting a typical semiconducting behavior, apart from the sample with the maximum Ag concentration acting as a degenerate semiconductor, whereas the Seebeck coefficient measurements indicate n-type doping for all the samples. The power factor values (up to 14.9 µW cm−1 K−2 at 540 K for the nominal 10% Ag concentration sample) are competitive for low-power applications on flexible substrates, also presuming the achievement of a large reduction in the thermal conductivity thanks to the native nanostructuring.

Enhancement of Thermoelectric Performance for InTe by Selective Substitution and Grain Size Modulation

The different masses, ionic radii, and chemical valences of the nonequivalent crystallographic sites of thermoelectric (TE) compounds provide an effective way to modulate the thermoelectric performance by selective substitution. In this work, the selective substitution of In+ by Pb for the binary InTe material monotonically reduces the carrier concentration, which is greatly beneficial to the mechanism investigation of serious grain boundary scattering (GBS). This is the first time this point has been mentioned with regard to InTe material. As a result, we found that GBS was dominated by the grain size when the carrier concentration was higher than 0.7 × 1019 cm−3 but was inversely governed by the carrier concentration when the carrier was situated at a lower density. In particular, the occupation of Pb on the targeted In+ site could further reduce the lattice thermal conductivity. Finally, In0.9999Pb0.0001Te achieved the improved power factor and average zT value, which could contribute to high-power generation below a medium temperature. This effect of increasing the carrier concentration on the suppression of GBS sheds light on the possibility of improving electron mobility by increasing the carrier concentration.

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.

Pd quantum dot induced changes in the photocatalytic, electrocatalytic, photoelectrochemical and thermoelectric performances of galvanically synthesized Sb2Se3 thin films

We present a novel solution-based galvanic (electrochemical) synthesis of antimony selenide light absorber thin films on FTO (Fluorine doped tin oxide) coated glass substrates. The structural, surface morphological, compositional, optical and electrical properties of the samples were characterized using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Fast Fourier Transform (FFT), Energy Dispersive X-ray spectroscopy (EDS), UV–Vis and Photoluminescence (PL) spectroscopy and Electrochemical Impedance spectroscopy (EIS). X-ray Photoelectron Spectroscopy (XPS) was employed to determine the elemental state composition of as-deposited and annealed Sb2Se3 films containing Pd. The annealed Sb2Se3:Pd films exhibited hydrogen evolution in neutral buffer medium with small potential of 164 mV and a Tafel slope of 39 mV/decade. Pd incorporation enhances the efficiency towards HER performance, which shows the 10 mAcm−2 current density at a low overpotential of 244 mV with reasonable durability. Photoelectrochemical (PEC) water splitting was observed at a potential of 0.41 V versus a reversible hydrogen electrode (RHE) with 3.2 mA cm−2 at 0 V versus RHE, under air mass 1.5 global illumination in a neutral electrolyte. To check the performance of this material for waste water treatment photodegradation of hazardous dyes and metal ion reduction experiments were performed. The photodegradation percentages of MG, MB and RhB dyes with annealed Sb2Se3:Pd thin film catalysts and H2O2 were 99.32% in 10 min, 98.95% in 20 min and 99.16% in 30 min, respectively. Cu2+ ions were photocatalytically reduced with the same catalyst to an extent of 98.9% in 20 min. Thermoelectric measurements on annealed Sb2Se3:Pd yielded the best Figure of merit and power factor values of 39.8 μW/cmK2 and 10.81 × 10−3, respectively at 373 K.

Regioisomeric Cyanated Polythiophenes Bearing Polar Side Chains for n-Type Organic Thermoelectrics

The development of n-type polymers with high thermoelectric performance remains a major challenge for organic thermoelectrics. Herein, by devising two new isomeric cyano-functionalized bithiophene building blocks bearing polar side chains, we report two novel donor–acceptor-configurated n-type polythiophene polymers (BTOgCN-FT and BTCNOg-FT) with regiochemically tuned intramolecular S···O noncovalent interactions (INIs) and cyanation patterns for n-type thermoelectric application. The results show that cyanation furnished low-lying LUMO energy levels approaching that of the benchmark n-type polymer N2200 for both polymers (∼−3.90 eV), which combine with their polar side chain-enabled high dopant miscibility, leading to efficient n-doping efficiencies. Detailed theoretical and experimental studies also suggest that BTOgCN-FT exhibited a more planar backbone conformation and more ordered interchain packing in film state, thus yielding higher electrical values than BTCNOg-FT. Therefore, the polymer BTOgCN-FT eventually displays an optimal power factor (PF) value of 2.77 μW m–1 K–2, which is higher than that of BTCNOg-FT (1.50 μW m–1 K–2) and also largely outperforming that of the thoroughly investigated and optimized polymer N2200 (typical PF value of 10–2 μW m–1 K–2). Our work not only presents two novel structurally simple and isomeric electron-accepting building blocks but also offers valuable structure–property correlations for the future design of high-performance n-type thermoelectric materials.

Electronic Transport Properties of Bi<sub>2</sub>Te<sub>2.7</sub>Se<sub>0.3</sub> Fabricated by Hot Extrusion

Herein we report the optimized processing conditions of hot extrusion for fabricating an <i>n</i>-type Bi<sub>2</sub>Te<sub>2.7</sub>Se<sub>0.3</sub> thermoelectric compound, with high electronic transport properties as well as improved mechanical reliability. We fabricated a Bi<sub>2</sub>Te<sub>2.7</sub>Se<sub>0.3</sub> extrudate that was 3.8 mm in diameter and 700 mm in length by controlling the processing parameters of temperature and pressure. A 3-point bending strength of over 70 MPa, which is 7 times higher that of the commercial zone melting ingot, was obtained in the samples prepared at 460 <sup>o</sup>C temperature under 6–6.5 MPa pressure. The samples benefitted from the formation of a highly-dense microstructure (relative density > 98%). It is noted that the electronic transport properties (electrical conductivity and Seebeck coefficient) could be manipulated by controlling the applied pressure of hot extrusion at 460 <sup>o</sup>C, mainly due to the change in the characteristics of the 00<i>l</i> crystal orientation, which originated from grain rotation and rearrangement. Power factor values of ~2.9 mW/mK<sup>2</sup> at 300 K and ~2.95 mW/mK<sup>2</sup> at 320 K, similar to those of sintered bulks, were obtained in the hot extrudate fabricated under processing parameters of 460 <sup>o</sup>C and 6 MPa. Moreover, a high power factor value of 2.25 mW/mK<sup>2</sup> was observed even at the high temperature of 480 K, which is 70% higher than that of Bi<sub>2</sub>Te<sub>2.7</sub>Se<sub>0.3</sub> bulk fabricated by hot pressing.

Повышение качества электроэнергии в системах электроснабжения прокатных станов с использованием преобразователей частоты с активными выпрямителями за счет применения специализированных пассивных фильтров

In recent years, the frequency converters (FC) with active rectifiers (AR) have become widespread due to their advantages. The advantages are the possibility of energy recovery in braking modes of electric drive and support of the set value of power factor at the input of AR. At the same time these converters have a significant disadvantage, that is the deterioration of voltage quality in the in-plant 6–35 kV power distribution network due to the imposition of high-frequency harmonics of the input voltage and current of AR on the resonant area of the supply network frequency response. This disadvantage can be eliminated by using special passive filters in the in-plant power networks. They ensure the shift of the main resonance of currents to a zone free from high-frequency harmonics of the FC with AR. It makes possible to reduce the harmonic distortion coefficient in the voltage sections of the main stepdown substation (MSS) of the enterprise. Processing of experimental data is carried out in the Matlab mathematical package with the Simulink application. Using income data of functioning metallurgical complex CherMK of PJSC “Severstal”, the authors carried out the analysis of voltage quality of 10 kV network using specialized passive filters and without them. The article presents the results of the study of the effectiveness of the use of specialized passive filters in the in-plant power supply system of the rolling complex operating at the CherMK of PJSC “Severstal”. The reasons of the deterioration of the voltage quality in the 10 kV distribution network are studied, and as a result, operational breakdown of the modes of sensitive electrical receivers. A complex mathematical model of the 10 kV network has been developed to study the way to improve the harmonic composition of voltage due to installation of specialized passive filters. This filter allows you to adjust the frequency characteristics of the 10 kV network, shift it to an area free of high-frequency harmonics generated by modern frequency converters with active rectifiers. Thus, the resonance of currents and voltages in 10 kV sections is eliminated. As a result, a significant improvement in the shape of the line voltage and a decrease in the harmonic distortion coefficient of voltage THDU = 75,2–91,2 % to values THDU = 0,49–1,4 % is observed. The main result of the research is the recommendation to use a specialized passive filter to eliminate the negative impact of the harmonic component of the current resonance. The research results can be used to design power supply systems of metallurgical enterprises that have powerful electric drives with active rectifiers.

Precursor-Led Grain Boundary Engineering for Superior Thermoelectric Performance in Niobium Strontium Titanate.

We present a novel method to significantly enhance the thermoelectric performance of ceramics in the model system SrTi0.85Nb0.15O3 through the use of the precursor ammonium tetrathiomolybdate (0.5-2% w/w additions). After sintering the precursor-infused green body at 1700 K for 24 h in 5% H2/Ar, single-crystal-like electron transport behavior developed with electrical conductivity reaching ∼3000 S/cm at ∼300 K, almost a magnitude higher than that in the control sample. During processing, the precursor transformed into MoS2, then into MoOx, and finally into Mo particles. This limited grain growth promoted secondary phase generation but importantly helped to reduce the grain boundary barriers. Samples prepared with additions of the precursor exhibited vastly increased electrical conductivity, without significant impact on Seebeck coefficients giving rise to high power factor values of 1760 μW/mK2 at ∼300 K and a maximum thermoelectric figure-of-merit zT of 0.24 at 823 K. This processing strategy provides a simple method to achieve high charge mobility in polycrystalline titanate and related materials and with the potential to create "phonon-glass-electron-crystal" oxide thermoelectric materials.

High Thermoelectric Performance and Oxidation Resistance of (Na, Ga) Codoped β-Zn4Sb3 Thermoelectric Materials Prepared by the NaCl Flux

β-Zn4Sb3 is a promising thermoelectric (TE) material, as it contains low-cost and environment-friendly elements. However, its application has long been limited due to the lower figure of merit (ZT), poor mechanical properties, and inferior thermodynamic stability. In this research, we successfully synthesized Na/Ga codoped β-Zn4Sb3 with high thermoelectric performance and stability. The power factor (PF) value of the Ga-doped sample is significantly improved by optimizing carrier concentration, the maximum value of 2.28 × 10–3 W m–1 K–2 is obtained at 690 K, and the maximum ZT reaches 1.73 at 690 K for the Zn4.1Sb3(NaCl)7Ga0.12 sample. Moreover, the TG-DSC and oxidation resistance tests show that Na and Ga codoped β-Zn4Sb3 possess good stability. This work provides an attractive method for improving the thermoelectric properties and stability of β-Zn4Sb3 through diatomic doping.

Kajian Manajemen Energi Listrik Pada Stasiun Pompa Air

One of the important components for a drinking water company is the operation of a pump station that functions to regulatethe water supply from existing water sources to customers. To operate the water pump, an electric motor is needed as the driving force. Inorder for the energy consumption needed to operate an electric motor to be regulated, it is necessary to manage electrical energy at thepump station. One example of a pump station is the local water company (PDAM) Unit Wendit Malang City. This unit consists of 3 pumpstations namely Wendit 1, Wendit 2 and Wendit 3. These three parts are supplied by 2 transformers with a capacity of 1110 kVA for Wendit2 and 1730 kVA for Wendit 1 and 3.From the results of power factor measurements in the three sections , it is known that the power factorvalue at the Wendit 3 pump station is 0.82. This value does not meet the PLN minimum standard, which is 0.85. If the power factor is lessthan 0.85 then the industry will incur the excess reactive power consumption (kVARh) charges. Therefore it is necessary to study energymanagement at the pump station of PDAM Unit Wendit Malang City. To improve the low power factor, two recommendations were given,namely the installation of VSD (Variable Speed Drive) at the PDAM Unit Wendit 1 and 3 pump stations and the installation of a CapasitorBank at the PDAM Unit Wendit 2 pump station.Based on the analysis, the power factor value PDAM Wendit 3, which was originally 0.82increased to 0.9. In addition, there are savings in electricity consumption per month of 10.48% at PDAM Unit Wendit 1 and 3 and 28.32%at PDAM Unit Wendit 2.

Analisa Audit Energi Listrik di PT. Ispat Bukit Baja Kota Bekasi

PT. Ispat Bukit Baja is a company engaged in the steel production industry. Every component production uses electricalenergy as the main source. With the main load of lighting, air conditioning, and electric motors, the use of electricity in this company is verylarge and important. An audit energy needs to be carried out because the value of Energy Consumption Intensity in 2020 is 251 kWh / m2/ year and in 2021 it is 221 kWh / m2 / year and the value of Specific Energy Consumption in 2020 is 0.26 GJ / Ton and in 2021 is 0.29GJ/Ton. The energy audit method used is to calculate the value of Energy Consumption Intensity and Specific Energy Consumption. Thesavings opportunities made are on the air conditioning system, lighting system, and electric motor load. From the results of the analysisand calculation of savings in the air conditioning system, savings of 50.1% or 67.70 kWatt were obtained using a psychrometric diagramto determine the cooling system according to the needs of the room, then for the lighting system, savings of 21.9% or 6 kWatt by replacingthe installed lighting system with energy-saving lamps, then the load of the electric motor is using capacitor to improve the power factorvalue which was originally 0.77 to 0.85 with the aim that the motor speed does not change which will result in the precision of the productionobtained savings in the use of apparent power of 7.13% or 126.52 kVA. So that the results of the apparent power savings can be used forbackup. The total recommended power saving obtained from the calculation results is 73.7 kWatt. So based on the calculation of the energyaudit that has been done, it can reduce production costs and energy use efficiency

Compositing Nanostructured Polyaniline with Single-Walled Carbon Nanotubes for High Thermoelectric Performance

In the face of the growing energy crisis and demand on environmental protection, organic thermoelectric (TE) materials have been coming under the spotlight from global researchers as a potential countermeasure. However, there have been few studies on the relationship between the morphology of conductive polymers (CPs) and their TE performance. In this work, nanostructured polyaniline (PANI) was synthesized by interfacial polymerization with the addition of organic solvents of different polarities, including cyclohexane (CYH), carbon tetrachloride (CCl4), toluene (MB), dichloromethane (DCM), and dimethyl sulfoxide (DMSO). Physical mixing PANI with single-walled carbon nanotubes (SWCNTs) affords PANI/SWCNT composites. The composite of PANI nanobelts and 10 wt% SWCNTs achieves a power factor (PF) of 5.13 ± 0.56 μW m-1 K-2 at room temperature (RT). Spherical PANI doped with 50 wt% SWCNTs followed by pressing affords maximal room temperature PF value of 178.10 ± 3.77 μW m-1 K-2. A prototype TE generator (TEG) constructed with seven pairs of legs of as-prepared PANI/SWCNT composites and their n-type counterparts generates voltage of 10.27 ± 0.15 mV and output power of 36.65 ± 1.18 nW at temperature difference of about 50°C. This work illustrates that well-regulated PANI nanostructure could significantly affect the TE properties of PANI/SWCNT composites, which are promising in future preparation of high-performance polymer-based composites regarding the fabrication of TE devices suitable for harnessing low-grade waste heat.

Electronic, Thermal, and Thermoelectric Transport Properties of ReSe2 and Re2Te5

Re-based chalcogenides have been studied in various fields such as strain engineering, photodetection, spintronics, and electromechanics, as well as in piezoelectric and photonic devices. In this study, the electrical, thermal, and thermoelectric transport properties of two representative Re-based chalcogenides, ReSe2 and Re2Te5, are investigated systematically. Furthermore, their electronic band dispersions are calculated using density functional theory and compared with the phenomenological data. The maximum power factor values for the ReSe2 and Re2Te5 were measured 0.0066 and 0.11 mW/mK2 at 880 K, respectively. Thermal conductivity of layered ReSe2 at room temperature was between 1.93 and 8.73 W/mK according to the measuring direction. For Re2Te5 with a complex orthorhombic crystal structure, the thermal conductivity was quite low in the range between 0.62 and 1.23 W/mK at room temperature. As a result, the maximum z T values of ReSe2 were quite low as 0.0016 at 880 K due to very low power factor and high thermal conductivity. Meanwhile, the relatively high z T of 0.145 in Re2Te5 is obtained at 880 K, which is originated from the acceptable power factor value and the low thermal conductivity.

Bi2Te3 nanowires tuning PEDOT:PSS structure for significant enhancing electrical transport property

We developed Bi2Te3 nanowires (NWs)/poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) with a high power factor (PF) value of 170 μW·m−1·K−2 by a simple pulling method, which is an 85-fold improvement over PEDOT:PSS. The XRD, FTIR, UV–vis-NIR, XPS, FESEM, and NanoMap co-confirm the significant increase in electrical transport performance mainly attribute to two vital factors. First, the π bond of PEDOT:PSS interacts with the van der Waals force between the Te atom layer of Bi2Te3 NWs in the composite film, which makes PEDOT:PSS change from benzene type structure to quinone type structure with high conductivity. Second, the energy filtering effect generated by the interfacial barrier between Bi2Te3 NWs and PEDOT:PSS promotes the increase of seebeck coefficient.

Enhanced Thermoelectric Performance of CoSb3 Thin Films by Ag and Ti Co-Doping.

The Skutterudites CoSb3 material has been the focus of research for the conversion applications of waste heat to electricity due to its ability to accommodate a large variety of ions in the cages that have been proven effective in improving the thermoelectric performance. Although the co-doped CoSb3 bulk materials have attracted increasing attention and have been widely studied, co-doped CoSb3 thin films have been rarely reported. In this work, Ag and Ti were co-doped into CoSb3 thin films via a facile in situ growth method, and the influence of doping content in the thermoelectric properties was investigated. The results show that all the Ag and Ti co-doped CoSb3 thin films contain a pure well-crystallized CoSb3 phase. Compared to the un-doped thin film, the co-doped samples show simultaneous increase in the Seebeck coefficient and the electrical conductivity, leading to a distinctly enhanced power factor. The high power factor value can reach ~0.31 mWm-1K-2 at 623 K after appropriate co-doping, which is two times the value of the un-doped thin film we have been obtained. All the results show that the co-doping is efficient in optimizing the performance of the CoSb3 thin films; the key point is to control the doping element content so as to obtain high thermoelectric properties.

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.

Analisa Harmonisa Pada Unit Crane RTG (Rubber Tyred Gantry) Di PT. Nilam Port Terminal Indonesia

RTG (Rubber Tyred Gantry) Crane tends to have harmonic distortions. It is caused by the VSD switching process that converts current from DC to AC, decreasing the power quality and affecting power generation. Disturbance tends to happen on voltage or a current sine wave of the system that contains multiplied frequency from fundamental frequency. It is required to analyze based on the IEEE standard of Std 519-2014 which described that the 20kV bus voltage has a limit value of 3% for VIHD and 5% for VTHD. By using available software, simulation is applied to the RTG Crane electrical system. Harmonic distortion will be discussed by gathering simulation result data in the form of the harmonic spectrum and harmonic wave. harmonic filter to be applied is an Active Filter and Passive Filter that then compared the compatibility to solve the harmonic distortion. The analysis is also applied to Power Factor (PF) value changes before and after filter installation.

First principles calculations to investigate structural, electronic, mechanical, thermoelectric and optical properties of Bi- and Se-doped SnTe

Lead-based thermoelectric materials have a maximum figure of merit but are hazardous to humans and the environment. For this reason, we can replace tin-based lead-free materials and achieve the same figure of merit as lead-based thermoelectric materials. In this paper, we calculate the structural, electronic, mechanical, thermoelectric and optical properties of SnTe by co-doping it with Bi and Se using first principles calculation within the Generalized Gradient Approximation (GGA) through the Perdew-Burke-Ernzerhof(PBE) correlation scheme. Cohesive energies were calculated for each co-doping material and found to be maximum for Sn0.875Bi0.125Te0.875Se0.125. Computed elastic constants of all the cubic materials were obtained using the Thomas Charpin method integrated with the World of Interacting Electron and Nuclei due-2 Walter Kohn (WIEN2k) package. We found several mechanical properties of each material based on these constant values. We have observed an improvement in ductility and good stability for the Sn0.125Bi0.875Te0.125Se0.875 material as confirmed by various mechanical properties. Boltzmann semi-classical approach as implemented in the BoltzTraP package with and without the calculation of spin-orbit coupling. Here the figure of merit is calculated without the contribution of phonons and SOC calculations were included with the ambient conditions. From the results, we achieve maximum power factor and ZT values using SOC and non-SOC calculations. We identified that the Sn0.875Bi0.125Te0.875Se0.125 material shows a maximum ZT of 0.55, which is very much higher than the undoped SnTe and Sn0.125Bi0.875Te0.125Se0.875 material shows a ZT of 0.49 using SOC calculations. The optical properties of each material were studied at ambient conditions and Sn0.875Bi0.125Te0.875Se0.125 is consistent in the visible, IR and UV regions and it is adorable for IR detectors, solar cells and optoelectronic applications.

Thermoelectric and power generation of 2D structured pieces of graphene-nanodiamonds nanocomposite.

Recently, the ultrafine 2D structured nanocomposite of graphene (Gr)-nanodiamonds (NDs) produced by a microwave-assisted chemical route was found to have attractive structural properties. This new 2D structured nanocomposite may be employed for a wide spectrum of applications including thermoelectricity (TE) applications. It is well established that TE materials should be highly effective to be used for designing operative devices for powering or cooling small devices. To fulfill such an objective, the functional TE material should possess a high-power factor and low thermal conductivity. In this study, NDs were successfully integrated into Gr with a magnificent structural alteration to the Gr layers/sheets. This structural modification was found to impact the TE final outcome above and below room temperature (RT). The obtained results showed that at 215 K the power factor value was increased from 4 μW m-1 K-2 for the pure Gr to ∼20 μW m-1 K-2 for the Gr-NDs nanocomposite. At higher T, e.g. 365 K, these values slightly decreased, but with clear superiority for the Gr-NDs nanocomposite. The thermal conductivity of the Gr-NDs nanocomposite was significantly reduced to ∼12% of that of the pure Gr, which could reflect a significant enhancement in the value of the figure of merit by >45 times. Furthermore, the output power generated by a single small leg module made of the Gr-NDs nanocomposite was measured and found to be measurable. The obtained values are still relatively low for practical application, but this newly produced material has great potential to be further developed for TE applications.