Gallium Content Research Articles

Effect of Gallium Content on Diode Characteristics and Solar Cell Parameters of Cu(In1-xGax)(Se0.98Te0.02)2 Thin Film Solar Cells Produced by Three-stage Co-evaporation at Low Temperature

In this study, Cu(In1-xGax)(Se0.98Te0.02)2 thin film solar cells with x values of 0.17, 0.20, 0.23, and 0.26 were successfully produced by three-stage co-evaporation technique at low temperatures. The diode characteristics and solar cell parameters of thin film chalcopyrite solar cells with the structure of SLG/Mo/Cu(In1-xGax)(Se0.98Te0.02)2/CdS/ZnO/ITO/Ni-Al-Ni were investigated by current-voltage measurements. The ideality factor, series resistance, and barrier height were obtained by the Cheung-Cheung method using the current-voltage results measured in the dark at room temperature. Open-circuit voltage, short-circuit current density, fill factor, and the power conversion efficiency of the thin film solar cells were derived from the current-voltage measurements realized by a four-point measurement setup under AM1.5G standards at room temperature. It was found that the increase in the gallium content first decreased the ideality factor, however, it increased again after exceeding the x value of 0.23. While the amount of gallium was increasing, fluctuations were observed in the series resistance values. The barrier height first increased with the increasing amount of gallium and decreased after exceeding the x value of 0.23. The solar cell parameters increased by increasing the x value up to 0.23 and decreased after exceeding this point. It was found that the diode parameters have an effect on each other but the most effective diode parameter was the ideality factor. The efficiency of the Cu(In1-xGax)(Se0.98Te0.02)2 thin film solar cells was increased from 3.7% to 6.3% by increasing the x value from 0.17 to 0.23.

A synergistic approach in designing InP/ZnS quantum dot based CIGS solar cell

This research work investigates the implementation of non-toxic InP/ZnS quantum dot (QDs) buffer layer in solar cell. Due to its nontoxic behaviour, it is a better replacement of commonly used CdS buffer layer. InP/ZnS quantum dots buffer layer enhances light absorption, leading to a broader spectral response and improved power conversion efficiency. Graded CIGS (CuIn1-xGaxSe2) is used as absorber layer in this study for better utilization of solar spectrum. The combined utilization of an InP/ZnS QD buffer layer and a graded absorber layer results in a synergistic enhancement of the cell's performance. Further optimization of CIGS layers is achieved by varying the gallium content (x) in the Cu(In1−xGax)Se2. For the gallium content (x) in the range of 0.20 to 0.15, maximum efficiency is achieved which is 31.20 %. Numerical modeling is employed in this study to analyze how variations in thickness, doping concentration, and defect density impact the solar cell performances.

Gallium-Doped Hydroxyapatite: Shape Transformation and Osteogenesis Activity.

In this study, we employed a chemical precipitation method to successfully synthesize nanoparticles of gallium-doped hydroxyapatite (Ga-HAp). The microstructure of Ga-HAp was precisely tailored by modulating the concentration of gallium ions. Our findings unequivocally demonstrate that gallium ions exert a pronounced inhibitory influence on the growth of HAp crystals, and this inhibitory potency exhibits a direct correlation with the concentration of gallium. Furthermore, gallium ions facilitate the metamorphosis of HAp nanoparticles, transitioning them from nanoneedles to nanosheets. It is worth noting, however, that gallium ions exhibit a limited capacity to substitute for calcium ions within the crystal lattice of HAp, with the maximum substitution rate capped at 4.85%. Additionally, gallium plays a pivotal role in constraining the release of ions from HAp, and this behavior remains consistent across samples with varying Ga doping concentrations. Our in vitro experiments confirm that Ga-doped HAp amplifies both the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells.

TWO TYPES OF GALLIUM EXPOSURE TO ALUMINUM

The effect of gallium on aluminum during their fusion is investigated. The corrosion rate of aluminum alloys with 1, 2 and 5 at % gallium content was experimentally determined, which was 0.001, 0.00101 and 0.00062 g/m2 · h, respectively, which is less than that of pure grade A99 aluminum – 0.0016 g/m2 · h. The rate of dissolution of these alloys in acidic and alkaline media is determined. X-ray phase analysis showed the homogeneity of the alloys under consideration. The morphology of aluminum alloys with gallium was studied, after exposure to an aggressive environment – a solution of hydrochloric acid. The possibility of obtaining hydrogen and nanoscale alumina by decomposition of water by activated gallium aluminum alloy is shown. Activation of the aluminum surface by gallium alloy occurs according to the Rebinder effect and the article presents a micrograph of the surface of aluminum treated with Ga-Sn alloy, clearly demonstrating this effect. When using metallic gallium in contact with aluminum, the interaction requires heating to a temperature above 30°C (the melting point of gallium is 29.7°C), the melting point of the eutectic composition 92Ga–8Sn is 20.0°C, which allows the interaction to begin at room temperature. At temperatures of about 4°C, activated aluminum can be stored for a long time. The quality of hydrogen obtained by decomposition of water should be higher than that obtained by cracking, and the cost is close to a well-developed technology of electrolysis of water and no more than 2 times the cost of its synthesis via cracking of hydrocarbons. Gallium and its liquid alloys are non-toxic, almost do not interact with water, activate aluminum, preventing the formation of a protective oxide film, penetrate into the intergranular space and aluminum easily interacts with water, forming hydrogen and aluminum hydroxide.

Phase formation during crystallization of melts and glasses of the GaxGe40-xS60 system

The purpose of this work is to study phase formation during quenching of glass-forming melts and crystallization of GaxGe40-xS60 glasses (x = 0–15 at.%), which are promising materials for optical IR glass-ceramics. The stability against crystallization of the glasses is determined to decrease with increasing gallium content. In the case of the glass-forming melts, the stability against crystallization increases in the range x = 0–8 at.% and then decreases. It is established that, during crystallization, not pure phases of binary sulfides are formed, but their solid solutions. When quenching the melts with a gallium content of 10–15 at.%, Ga2-xGexS3 solid solutions, which are isostructural to one of the polymorphic modifications of gallium sesquisulfide, are crystallized. Solid solutions form skeletal crystals, the growth of which leads to the formation of a dendritic crystal structure. Micro-liquation in the GaxGe40-xS60 glasses is observed.

Hydrometallurgical processing of ash and slag waste

This work assesses the possibility of hydrometallurgical processing of ash and slag waste in order to extract rare and rare earth elements. The ash and slag waste from the Chita CHPP-2 combined heat and power plant was used as a research object. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to determine the elemental chemical composition of coal combustion products. To preconcentrate rare and rare earth elements, magnetic separators were used to isolate the -0.5+0.3 mm and -0.3+0.1 mm grain size fractions of ash and slag waste. The leaching of rare and rare earth elements from the studied samples was investigated using sulfuric, hydrochloric, and nitric acids, as well as an aqua regia solution, in combination with simultaneous ultrasonic exposure. It was determined that electromagnetic separation of the -0.5+0.3 mm and -0.3+0.1 mm grain size fractions of ash and slag waste significantly concentrates rare and rare earth elements in the magnetic fraction, including titanium (up to 25%), zircon (up to 33%), yttrium (up to 50%), lanthanum (up to 150%), and cerium (up to 5%). It was determined that an increase in the duration of ultrasonic treatment during the leaching of metals from ash and slag waste with sulfuric acid resulted in a uniform 7.25-fold increase in gallium content (from 0.008 to 0.058 g/dm3). Additionally, when decomposed with aqua regia, a 3-fold concentration of the same element was observed (from 0.008 to 0.024 g/cm3), while ultrasonic treatment offered only a slight increase in concentration. When leaching with sulfuric acid (the duration of ultrasonic exposure is 5 minutes), a 4-fold increase in the rubidium content was observed (from 0.108 to 0.457 mg/dm3). Therefore, the most effective method for extracting rare and rare earth elements from the ash and slag waste of Chita CHPP-2 involves acid leaching combined with electromagnetic separation and ultrasonic pulp leaching.

Trace Metal Based Eco-Biological and Health Risk Status of Surface Water and Sediments of Noyyal River Basin, Tamil Nadu, India

ABSTRACT Pollution in the Noyyal river is a well-known and documented issue and recently, heavy metal contamination has become a serious issue requiring immediate attention. So, to understand the severity of heavy metal contamination in the surface water and sediments of the Noyyal river, a comprehensive study was conducted. About 27 surface water samples and 25 sediment samples were collected at different sites along the Noyyal river. The concentrations of heavy metals were determined using inductively coupled plasma mass spectrometry (ICP-MS). The Noyyal river’s surface water showed significant variations with nickel (Ni), copper (Cu), and zinc (Zn) concentrations exceeding acceptable limits for irrigation and aquatic life. Lead (Pb) concentrations were within acceptable limits for irrigation but potentially harmful to aquatic organisms. Noyyal river sediments also contained varying concentrations of chromium (Cr), copper (Cu), nickel (Ni), zinc (Zn), and gallium (Ga). Various assessment indices were employed to assess the eco-biological and human health risks associated with heavy metal contamination. The results highlighted alarming ecological and biological risks due to the accumulation of trace metals. Sediments exhibited high ecological risk (ERI values ranging from 43.81 to 371.43), while surface water samples intended for irrigation and aquatic purposes displayed extreme risks (ERI values exceeding 1200) to agricultural crops and aquatic organisms. The probability of toxicity to aquatic organisms, particularly benthic communities, was over 76% according to the biological risk assessment. The study also identified potential non-carcinogenic risks associated with metals like chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn) in the sediments. Moreover, elevated levels of Cr, Ni, and Cu in both sediments and surface water were likely to pose significant carcinogenic risks to exposed adults. Additionally, the heavy metal toxicity load in both surface water and sediments exceeded permissible limits, highlighting the urgent need for efficient removal strategies.

A new method for pre-enrichment of gallium and lithium based on mode of occurrence in coal gangue from Antaibao surface mine, Shanxi Province, China

The presence of a notable concentrations of gallium (Ga) and lithium (Li) in coal gangue, an industrial solid waste, has attracted widespread attention. However, utilization of these resources remains an economic challenge. This study entailed an investigation of the potential of the pre-enrichment of Ga and Li in coal gangue so as to effectively utilize coal gangue resources. The modes of occurrence of Ga and Li in coal gangue were studied using a sequential chemical extraction procedure (SCEP), mineral phase composition, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and elemental content composition. The results indicate that the main mineral components of the coal gangue are mica, quartz, pyrite, and clay. Ga and Li are mainly associated with Al-containing minerals, such as mica and clay. Further, the main noncarrier minerals are quartz and pyrite. Ga and Al exhibit a high degree of correlation, whereas Li exhibits a predominant association with Al and Ti. Ga and Li are also negatively correlated with Fe and Sr. Moreover, sorting experiments demonstrated that the separation of Ga and Li from pre-enriched coal gangue is an effective and environmentally friendly method. This allowed for the discarding of 31.25% of the waste rock, with an Fe content of 32.69%. The concentrate products can potentially be high-quality raw materials for Ga and Li refining facilities, whereas the tailing products can serve as an effective source of iron ore raw materials.

Structural and Thermomagnetic Properties of Gallium Nanoferrites and Their Influence on Cells In Vitro.

Magnetite and gallium substituted cuboferrites with a composition of GaxFe3-xO4 (0 ≤ x ≤ 1.4) were fabricated by thermal decomposition from acetylacetonate salts. The effect of Ga3+ cation substitution on the structural and thermomagnetic behavior of 4-12 nm sized core-shell particles was explored by X-ray and neutron diffraction, small angle neutron scattering, transmission electron microscopy, Mössbauer spectroscopy, and calorimetric measurements. Superparamagnetic (SPM) behavior and thermal capacity against increasing gallium concentration in nanoferrites were revealed. The highest heat capacity typical for Fe3O4@Ga0.6Fe2.4O4 and Ga0.6Fe2.4O4@Fe3O4 is accompanied by a slight stimulation of fibroblast culture growth and inhibition of HeLa cell growth. The observed effect is concentration dependent in the range of 0.01-0.1 mg/mL and particles of Ga0.6Fe2.4O4@Fe3O4 design have a greater effect on cells. Observed magnetic heat properties, as well as interactions with tumor and healthy cells, provide a basis for further biomedical research to use the proposed nanoparticle systems in cancer thermotherapy (magnetic hyperthermia).

Using neutron diffraction to explore lithium displacement within cubic phase stabilised Ga-doped Li6.75La3Zr1.75Ta0.25O12 lithium garnet oxides

Typical Li6.75La3Zr1.75Ta0.25O12 exists as a mixture of tetragonal and cubic arrangements, but adding small amounts of Ga3+ (Li6.75–3xGaxLa3Zr1.75Ta0.25O12 x ≥ 0.1) resulted in a single cubic (I a-3d) phase lithium garnet oxide. Following the stabilisation of the cubic phase, the effects on lithium distributions were explored with neutron powder diffraction concerning Ga3+ content and temperature. Increasing the amount of Ga3+ reduced the amount of lithium within the structure, directly decreasing the Li 96h site occupancy and showing a minimal effect on the Li 24d site occupancy. High-temperature neutron diffraction studies revealed the migration of lithium from the Li 24d site to the Li 96h with increasing temperature. The inclusion of Ga3+ improved the total ionic conductivity over the gallium-free system. However, with increasing gallium content (x > 0.1), a negative correlation between the garnet's gallium content and total lithium ionic conductivity is observed, showing how the total amount of free lithium ions impact the system's total ionic conductivity. Though the electrolytes explored here show some limitations, the lithium-ion displacement trends with doping and temperature give us further insight into how these lithium garnet systems respond to chemical and physical change.

Concentration transition in Cu2(Mn,Ga)BO5 solid solutions

The effects related to the conversion of magnetic structures of a Cu2MnBO5 ferrimagnet to a Cu2GaBO5 antiferromagnet under the Mn3+ → Ga3+ substitution were studied. The properties of four single crystal samples with the gallium concentration x = 0.04, 0.11, 0.17, 0.25 were examined. The chemical composition and valence state of the samples were determined by X-ray absorption spectroscopy element-sensitive technique. Distribution of the 3d metal ions over crystallographic positions was studied using the first principle calculations by Wien2k program. The evolution of the magnetic properties was investigated by the measurements of the temperature and field dependences of magnetization, dc and ac magnetic susceptibility. In agreement with the previous study of the structure evolution of Cu2Mn1-xGaxBO5 solid solutions, the critical concentration upon a change in the magnetic ordering type was found in the range x = 0.17–0.25. The non-monotonic behavior of magnetization in terms of the gallium content was found in the concentration range of 0.04–0.17. A complex pattern of magnetic phase transitions belonging to the concentration phase boundary was obtained in the compounds with gallium being within the range x = 0.17–0.25. One could observe the splitting of the peaks of the real part of ac-susceptibility of the high-temperature phase transition in the Cu2MnBO5-like phase (x = 0.04, 0.11) and that of the low-temperature one at the concentration boundary (x = 0.17, 0.25) with different frequency and orientational dependence. The type and origin of the multiple phase transitions observed in the studied samples were analyzed.

Composition-Defined Optical Properties and the Direct-to-Indirect Transition in Core-Shell In1-xGaxP/ZnS Colloidal Quantum Dots.

Semiconductors are commonly divided into materials with direct or indirect band gaps based on the relative positions of the top of the valence band and the bottom of the conduction band in crystal momentum (k) space. It has, however, been debated if k is a useful quantum number to describe the band structure in quantum-confined nanocrystalline systems, which blur the distinction between direct and indirect gap semiconductors. In bulk III-V semiconductor alloys like In1-xGaxP, the band structure can be tuned continuously from the direct- to indirect-gap by changing the value of x. The effect of strong quantum confinement on the direct-to-indirect transition in this system has yet to be established because high-quality colloidal nanocrystal samples have remained inaccessible. Herein, we report one of the first systematic studies of ternary III-V nanocrystals by utilizing an optimized molten-salt In-to-Ga cation exchange protocol to yield bright In1-xGaxP/ZnS core-shell particles with photoluminescence quantum yields exceeding 80%. We performed two-dimensional solid-state NMR studies to assess the alloy homogeneity and the extent of surface oxidation in In1-xGaxP cores. The radiative decay lifetime for In1-xGaxP/ZnS monotonically increases with higher gallium content. Transient absorption studies on In1-xGaxP/ZnS nanocrystals demonstrate signatures of direct- and indirect-like behavior based on the presence or absence, respectively, of excitonic bleach features. Atomistic electronic structure calculations based on the semi-empirical pseudopotential model are used to calculate absorption spectra and radiative lifetimes and evaluate band-edge degeneracy; the resulting calculated electronic properties are consistent with experimental observations. By studying photoluminescence characteristics at elevated temperatures, we demonstrate that a reduced lattice mismatch at the III-V/II-VI core-shell interface can enhance the thermal stability of emission. These insights establish cation exchange in molten inorganic salts as a viable synthetic route to nontoxic, high-quality In1-xGaxP/ZnS QD emitters with desirable optoelectronic properties.

Modeling and optimization of CuIn1-xGaxSe2/Si1-yGey structure for solar cells applications

A combination of a Copper Indium Gallium Selenide (CIGS) and Silicon (Si) layer has been recognized as an excellent choice for producing heterojunction based solar cells with improved efficiency and low cost processing techniques. The quaternary compound CIGS and silicon (Si) regions exhibit a lattice mismatch of about 5%, which induces a strain and impacts the electronic characteristics of the CIGS/Si heterojunction solar cell. A new viewpoint suggests the integration of a silicon germanium (Si1-yGey) layer in the CIGS/Si region to reduce the impact of lattice mismatch. The objective of this study is to investigate how different gallium and germanium concentrations (xGa and yGe) affect the following factors: lattice mismatch (ε), critical thickness (hc) and absorption coefficient (α)of CIGS/SiGe based solar cells. It also aims to analyze how these concentrations impact the primary parameters used to evaluate solar cell performance such as external quantum efficiency, short circuit current density, fill factor, open circuit voltage and conversion efficiency. The simulation results agree well with the existing theoretical and experimental literature data, confirming the suitability of the physical characteristics employed in this numerical study. By tuning the concentrations of Gallium and Germanium, it is feasible to attain an efficiency of 24% owing to the lattice compensation phenomenon in Si1-yGey layers. These findings hold significant implications for the development and advancement of solar cell technology, as well as for enhancing their conversion efficiency and commercialization.

Extraction of Gallium from Brown Corundum Dust by Roasting—Acid Leaching Process

Brown corundum dust is a solid waste produced during the preparation of brown corundum with bauxite as the raw material. The dust has a relatively high gallium content; therefore, it is of great value to recover the gallium from this kind of dust. In this paper, a range of analysis and characterization methods, including XRD, XRF, SEM-EDS, and EPMA, were used to determine the occurrence of gallium. It was found that gallium was mainly present in the potassium-rich phase, wrapped by amorphous silicate and the corundum phase. Roasting activation followed by an acid leaching process was proposed to extract gallium from brown corundum dust. An investigation was carried out on the effects of roasting temperature, roasting time, and additive dosage on the recovery of gallium and the evolution of the phase composition of the dust. The results show that the roasting activation of sodium carbonate was better than that of calcium oxide. After roasting at 1073 K for 40 min with a sodium carbonate dosage of 0.5 (mass ratio of sodium carbonate to dust), the phase composition changed completely to mainly consist of sodium silicate, sodium aluminosilicate, and potassium aluminosilicate. In that case, around 93% of Ga could be recovered from the roasted dust through H2SO4 (4.6 mol/L) leaching for 90 min. The leaching process was described well by the kinetic equation of k3t = 1/(1 − α)1/3 − 1, with an apparent activation energy of 16.81 kJ/mol, suggesting that the leaching rate was limited by the transfer of leaching agent across the contacting interface of the dust particles.

Boosting oxygen activation in ceria-oxide via gallium addition

CeO2 is a well-suited support due to its higher oxygen storage capacity and reversible redox ability, which is associated with the oxygen activation. Herein we report the effective oxygen activation in CeO2 by gallium incorporation, varying the Ga/Ce molar ratios from 0.25 to 0.75. Structural results and operando spectroscopies under reaction conditions revealed that gallium incorporation improves the oxygen activation in CeO2, being more effective at low gallium content (Ga/Ce of 0.25). Atomic-scale computations demonstrated that the 0.25 Ga/Ce molar ratio generates Ga atomic-size channels that allow an easy way for oxygen diffusion from bulk to the surface. Ga incorporates into the subsurface Ce layer causing a collective effect: weakening the surface Ce-O bonds, boosting the surface oxygen activation, then enhancing the CO oxidation ability. Once this happens, it leaves behind O-vacancies, which may occupy either bulk oxygen from the CeO2 or further renovation of oxygen atoms from the environment.

Nano sized gallium oxide surface features for enhanced antimicrobial and osteo-integrative responses

Gallium oxide has known beneficial osteo-integrative properties. This may have importance for improving the osteointegration of orthopedic implants. At high concentrations gallium is cytotoxic. Therefore, integration of gallium into implant devices must be carefully controlled to limit its concentration and release. A strategy based on surface doping of gallium although challenging seems an appropriate approach to limit dose amounts to minimize cytotoxicity and maximize osteointegration benefits. In this work we develop a novel form of patterned surface doping via a block copolymer-based surface chemistry that enables very low gallium content but enhanced osteointegration as proven by comprehensive bioassays. Polystyrene-b-poly 4vinyl pyridine (PS-b-P4VP) BCP (block copolymer) films were produced on surfaces. Selective infiltration of the BCP pattern with a gallium salt precursor solution and subsequent UV-ozone treatment produced a surface pattern of gallium oxide nanodots as evidenced by atomic force and scanning electron microscopy. A comprehensive study of the bioactivity was carried out, including antimicrobial and sterility testing, gallium ion release kinetics and the interaction with human marrow mesenchymal stomal cells and mononuclear cells. Comparing the data from osteogenesis media assay tests with osteoclastogenesis tests demonstrated the potential for the gallium oxide nanodot doping to improve osteointegration properties of a surface.

Luminescence properties related anti-phase domain of alpha-Ga2O3

This work investigates the relationship between atomic arrangement and luminescence properties in a high-quality alpha-Ga2O3 thin film grown on an Al2O3 single-crystal membrane. The strain induced by merging domain boundaries shows more significant variability in annular darkfield images even though there is no additional gallium concentration confirmed. The bandgap energy of alpha-Ga2O3 is estimated to be 5.56 eV from the CL measurement in a transmission electron microscope. A peak at 320 nm was observed within the domain, while the domain boundary showed spectrum peaks with 380–480 nm. The anti-phase domain (APD) is formed by the instabilities of Al–O bonding templates provided by the Al2O3 substrate. The APD boundary gives a characteristic wavelength of 350 nm, which is the result of the merging boundary of in-phase and anti-phase domains.

Electrical and optical parameters optimization and interface engineering for efficiency improvement of double CIGS absorber based solar cell

In this paper, we present a numerical simulation of double CIGS absorber based solar cell to enhance solar cell performance. The performance characteristics such as open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF) and power conversion efficiency (PCE) were quantitatively analyzed using SCAPS-1D software. Ultrathin WSSe is used as buffer layer due to low reflectance and high bandgap which are favorable for photon transmission from front side to CIGS absorber layer. Optimization of energy bandgap of both CIGS absorbers layer has been done by varying the gallium content in Cu(In1-xGax)Se2 structure. The output characteristics measured here consist of the recombination velocity (S) at the WSSe/ Cu(In0.6Ga0.4)Se2 interface and doping concentration of the buffer and absorber layer. The PCE of double CIGS absorber based solar cell with gallium (Ga) content x=0.4 of Cu(In0.6Ga0.4)Se2 layer along with Ga content x=0.7 of Cu(In0.3Ga0.7)Se2 layer represents the record efficiency of 29 %. The results reveal that, it is possible to achieve PCE to 29 % and beyond and provide a promising solution towards the fabrication of highly efficient thin film CIGS photovoltaic cell.

Physical studies of CuIn1-xGaxSe2/Si1-yGey

The importance of combining the Copper Indium Gallium Selenide (CIGS) and Silicon (Si) for solar cell technologies outruns the limitations for their commercialization and the conversion efficiency limits. The lattice mismatch (about 5%) between chalcopyrite quaternary (CIGS) and silicon (Si) regions induces strain, affecting the electronic properties of the CIGS/Si hetero-junction solar cell, an innovative view suggests inserting a silicon germanium (Si1-yGey) layer into CIGS/Si interface to reduce the lattice mismatch effects. The impact of varying gallium and germanium concentrations (xGa and yGe) on the lattice mismatch, critical thickness and absorption coefficient of CIGS/SiGe based solar cells is investigated. As well as their effects on the main parameters used to characterize the performance of solar cells such as external quantum efficiency, open circuit voltage, short current density, fill factor and the conversion efficiency. Good agreement between simulation results and both existing theoretical and experimental literature data proves adequacy of the physical properties used in this numerical investigation. Optimizing Gallium and Germanium concentrations makes it possible to achieve an efficiency of 24% due to the lattice compensation effect in Si1-yGey layers.

Experimental Investigation of Liquid Metal Droplet on the Heat Transfer Performance in an Oscillating Heat Pipe

Abstract An oscillating heat pipe (OHP) charged with a hybrid fluid is investigated. This hybrid fluid uses an emulsion-based mixture of liquid metal gallium microdroplets suspended in an ethanol solution. The gallium microdroplets are fabricated using an ultrasonication technique. The OHP is fabricated from a copper plate and contains a six-turn channel with a 3 × 3 mm2 cross section. The heat transfer performance of the OHP was investigated experimentally with different concentrations of gallium at a 50% filling ratio. Steady-state oscillating motion was achieved with weight concentrations of gallium up to 20%. The experimental results show that using gallium-in-ethanol hybrid fluid emulsion as the working fluid can increase the heat transfer performance of the OHP by up to 7.8% over pure ethanol at 300 W. The mass of gallium needed to achieve this magnitude of heat transfer improvement is drastically reduced compared to previous research.