Gallium Selenide Research Articles

Epitaxy of GaSe Coupled to Graphene: From In Situ Band Engineering to Photon Sensing.

2D semiconductors can drive advances in quantum science and technologies. However, they should be free of any contamination; also, the crystallographic ordering and coupling of adjacent layers and their electronic properties should be well-controlled, tunable, and scalable. Here, these challenges are addressed by a new approach, which combines molecular beam epitaxy and in situ band engineering in ultra-high vacuum of semiconducting gallium selenide (GaSe) on graphene. In situ studies by electron diffraction, scanning probe microscopy, and angle-resolved photoelectron spectroscopy reveal that atomically-thin layers of GaSe align in the layer plane with the underlying lattice of graphene. The GaSe/graphene heterostructure, referred to as 2semgraphene, features a centrosymmetric (group symmetry D3d) polymorph of GaSe, a charge dipole at the GaSe/graphene interface, and a band structure tunable by the layer thickness. The newly-developed, scalable 2semgraphene is used in optical sensors that exploit the photoactive GaSe layer and the built-in potential at its interface with the graphene channel. This proof of concept has the potential for further advances and device architectures that exploit 2semgraphene as a functional building block.

Computational Optimization for CdS/CIGS/GaAs Layered Solar Cell Architecture

Multi-junction solar cells are vital in developing reliable, green, sustainable solar cells. Consequently, the computational optimization of solar cell architecture has the potential to profoundly expedite the process of discovering high-efficiency solar cells. Copper indium gallium selenide (CIGS)-based solar cells exhibit substantial performance compared to those utilizing cadmium sulfide (CdS). Likewise, CIGS-based devices are more efficient according to their device performance, environmentally benign nature, and thus, reduced cost. Therefore, the paper introduces an optimization process of three-layered n-CdS/p-CIGS/p-GaAs (NPP)) solar cell architecture based on thickness and carrier charge density. An in-depth investigation of the numerical analysis for homojunction PPN-junction with the ’GaAs’ layer structure along with n-ZnO front contact was simulated using the Solar Cells Capacitance Simulator (SCAPS-1D) software. Subsequently, various computational optimization techniques for evaluating the effect of the thickness and the carrier density on the performance of the PPN layer on solar cell architecture were examined. The electronic characteristics by adding the GaAs layer on the top of the conventional (PN) junction further led to optimized values of the power conversion efficiency (PCE), open-circuit voltage (VOC), fill factor (FF), and short-circuit current density (JSC) of the solar cell. Lastly, the paper concludes by highlighting the most promising results of our study, showcasing the impact of adding the GaAs layer. Hence, using the optimized values from the analysis, thickness of 5 (μm) and carrier density of 1×1020 (1/cm) resulted in the maximum PCE, VOC, FF, and JSC of 45.7%, 1.16 V, 89.52%, and 43.88 (mA/m2), respectively, for the proposed solar cell architecture. The outcomes of the study aim to pave the path for highly efficient, optimized, and robust multi-junction solar cells.

Increasing the efficiency of CIGS solar cells due to the reduced graphene oxide field layer of the back surface

Copper indium gallium selenide solar cells (CIGS-SCs) have gained attention due to their cost-effectiveness and environmentally friendly characteristics, making them a promising option for future electricity generation. The efficiency of CIGS-SCs can be enhanced by adding a back surface field layer (BSFL) under the absorber layer to reduce recombination losses. In this study, the electrical parameters, such as the series resistance, shunt resistance, and ideality factor, are calculated for CIGS-SCs with an advanced design, using the SC capacitance simulator (SCAPS) software. The detailed model used in the simulations considers the material properties and fabrication process of BSFL. By utilizing a reduced graphene oxide (rGO) BSFL, a conversion efficiency of 24% and a significant increase in the fill factor are predicted. This increase is primarily attributed to the ability of the rGO layer to mitigate the recombination of charge carriers and establish a quasi-ohmic contact at the metal-semiconductor interface. At higher temperatures, BSFL can become less effective due to an increased recombination and, in turn, a decreased carrier lifetime. Overall, this study provides valuable insights into the underlying physics of CIGS-SCs with BSFL and highlights the potential for improving their efficiency through advanced design and fabrication techniques.

Enhancing Multi-Junction Solar Cell Performance: Advanced Predictive Modeling and Cutting-Edge CIGS Integration Techniques

Historically, multi-junction solar cells have evolved to capture a broader spectrum of sunlight, significantly enhancing efficiency beyond conventional solar technologies. In this study, we utilized Silvaco TCAD tools to optimize a five-junction solar cell composed of AlInP, AlGaInP, AlGaInAs, GaInP, GaAs, InGaAs, and Ge, drawing on advancements documented in the literature. Our research focused on optimizing these cells through sophisticated statistical modeling and material innovation, particularly examining the relationship between layer thickness and electrical yield under one sun illumination. Employing III-V tandem solar cells, renowned for their superior efficiency in converting sunlight to electricity, we applied advanced statistical models to a reference solar cell configured with predefined layer thicknesses. Our analysis revealed significant positive correlations between layer thickness and electrical performance, with correlation coefficients (R2 values) impressively ranging from 0.86 to 0.96 across different regions. This detailed statistical insight led to an improvement in overall cell efficiency to 44.2. A key innovation in our approach was replacing the traditional germanium (Ge) substrate with Copper Indium Gallium Selenide (CIGS), known for its adjustable bandgap and superior absorption of long-wavelength photons. This strategic modification not only broadened the absorption spectrum but also elevated the overall cell efficiency to 47%. Additionally, the optimization process involved simulations using predictive profilers and Silvaco Atlas tools, which systematically assessed various configurations for their spectral absorption and current–voltage characteristics, further enhancing the cell’s performance. These findings underscore the critical role of precise material engineering and sophisticated statistical analyses in advancing solar cell technology, setting new efficiency benchmarks, and driving further developments in the field.

Economic and environmental sustainability of copper indium gallium selenide (CIGS) solar panels recycling

End-of-life management of copper indium gallium selenide (CIGS) thin-film solar photovoltaics (PV) panels is crucial due to the necessity of recycling valuable elements such as indium ($400/kg) and gallium ($618/kg), ensuring both economic viability and environmental sustainability. In this study, we analyze the private and external costs of end-of-life management for CIGS PV designed for mass-scale recycling. Our findings reveal that the private and external costs of end-of-life management range from ∼$3.5 to $4.5 and ∼$3.0 to $4.0 per m2, respectively. The chemicals utilized in the recycling process, particularly NaOH and HCl, significantly contribute to climate change, photochemical oxidant formation, particulate matter formation, and freshwater eutrophication impact categories, accounting for ∼50 % to 90 % of the impacts. Furthermore, we found the net cost of recycling by subtracting the economic benefit obtained from recovered materials from the sum of private and external costs, revealing values ranging between $4.3 and $5.7 per m2 of CIGS PV module. These findings suggest that there is room to reduce the net cost further by recovering more materials from the CIGS PV modules components.

Exploring the viability of secondary absorber materials in perovskite solar cell structures through computational analysis

Perovskite solar cells (PSCs) are at the forefront of next-generation photovoltaic technology due to their high efficiency and cost-effectiveness. To further enhance their performance, we investigate the integration of a second absorber layer alongside the conventional perovskite layer. Through extensive simulation techniques, we explore the effectiveness of silicon, Copper Indium Gallium Selenide (CIGS), and additional perovskite layers in forming a Double layered absorber perovskite solar cell (DLAPSC) structure. Our analysis of key performance metrics reveals MASnI3 as the most promising second absorber material, offering superior performance attributed to favorable band alignment and enhanced charge transport properties. In contrast, CIGS and Si layers exhibit inferior performance due to comparatively narrow bandgaps, leading to increased resistive losses. The perovskite/perovskite DLAPSC shows significant promise, achieving a notable power conversion efficiency of 41.56%. This study emphasizes the importance of meticulous parameter optimization and material selection in advancing PSC technology, highlighting the potential of DLAPSCs for renewable energy applications.

Thin Ga2O3 Layers by Thermal Oxidation of van der Waals GaSe Nanostructures for Ultraviolet Photon Sensing.

Two-dimensional semiconductors (2DSEM) based on van der Waals crystals offer important avenues for nanotechnologies beyond the constraints of Moore's law and traditional semiconductors, such as silicon (Si). However, their application necessitates precise engineering of material properties and scalable manufacturing processes. The ability to oxidize Si to form silicon dioxide (SiO2) was crucial for the adoption of Si in modern technologies. Here, we report on the thermal oxidation of the 2DSEM gallium selenide (GaSe). The nanometer-thick layers are grown by molecular beam epitaxy on transparent sapphire (Al2O3) and feature a centro-symmetric polymorph of GaSe. Thermal annealing of the layers in an oxygen-rich environment promotes the chemical transformation and full conversion of GaSe into a thin layer of crystalline Ga2O3, paralleled by the formation of coherent Ga2O3/Al2O3 interfaces. Versatile functionalities are demonstrated in photon sensors based on GaSe and Ga2O3, ranging from electrical insulation to unfiltered deep ultraviolet optoelectronics, unlocking the technological potential of GaSe nanostructures and their amorphous and crystalline oxides.

Giant nonlinear optical wave mixing in a van der Waals correlated insulator.

Optical nonlinearities are one of the most fascinating properties of two-dimensional (2D) materials. While tremendous efforts have been made to find and optimize the second-order optical nonlinearity in enormous 2D materials, opportunities to explore higher-order ones are elusive because of the much lower efficiency. Here, we report the giant high odd-order optical nonlinearities in centrosymmetric correlated van der Waals insulator manganese phosphorus triselenide. When illuminated by two near-infrared femtosecond lasers, the sample generates a series of profound four- and six-wave mixing outputs. The near-infrared third-order nonlinear susceptibility reaches near the highest record values of 2D materials. Comparative measurements to other prototypical nonlinear optical materials [lithium niobate, gallium(II) selenide, and tungsten disulfide] reveal its extraordinary wave mixing efficiency. The wave mixing processes are further used for nonlinear optical waveguide with multicolor emission. Our work highlights the promising prospect for future research of the nonlinear light-matter interactions in the correlated 2D system and for potential nonlinear photonic applications.

Scalable CIGS Solar Cells Employing a New Device Design of Nontoxic Buffer Layer and Microgrid Electrode.

The efficiency of copper indium gallium selenide (CIGS) solar cells that use transparent conductive oxide (TCO) as the top electrode decreases significantly as the device area increases owing to the poor electrical properties of TCO. Therefore, high-efficiency, large-area CIGS solar cells require the development of a novel top electrode with high transmittance and conductivity. In this study, a microgrid/TCO hybrid electrode is designed to minimize the optical and resistive losses that may occur in the top electrode of a CIGS solar cell. In addition, the buffer layer of the CIGS solar cells is changed from the conventional CdS buffer to a dry-processed wide-band gap ZnMgO (ZMO) buffer, resulting in increased device efficiency by minimizing parasitic absorption in the short-wavelength region. By optimizing the combination of ZMO buffer and the microgrid/TCO hybrid electrode, a device efficiency of up to 20.5% (with antireflection layers) is achieved over a small device area of 5 mm × 5 mm (total area). Moreover, CIGS solar cells with an increased device area of up to 20 mm × 70 mm (total area) exhibit an efficiency of up to 19.7% (with antireflection layers) when a microgrid/TCO hybrid electrode is applied. Thus, this study demonstrates the potential for high-efficiency, large-area CIGS solar cells with novel microgrid electrodes.

Perspectives on life cycle analysis of solar technologies with emphasis on production in India

The COVID-19 pandemic impacted the solar power industry, business, and supply chain for 2019–2021, and installations are falling behind the mission plan. However, Indian PV manufacturers see it as a chance to engage in solar manufacturing to establish a competitive, sustainable, and robust domestic solar industry instead of import-based installations. Given the country's current environmental concerns, green and sustainable local manufacturing is the only viable alternative. By conducting a life cycle assessment (LCA), this study compared the environmental impacts generated by the five most promising photovoltaic technologies-mono-silicon, polysilicon, copper indium gallium selenide (CIGS), cadmium telluride (CdTe), and passivated emitter and rear contact (PERC) solar modules considering manufacturing in India. The study utilizes the ReCiPe method supported by Ecoinvent 3 databases and Simapro V9.0 software, and the functional unit for the data collection is in ‘per square meter’, which is later converted to ‘per kWh’ standard for comparison with the existing studies. The system boundary selected is from cradle to gate. The results demonstrate that cadmium telluride (CdTe) is the best technology for Indian climatic conditions in terms of environmental impact, with a global warming potential of 0.015 kg CO2 eq/kWh, stratospheric ozone depletion of 5.41E-09 kg CFC11 eq/kWh, human carcinogenic and non-carcinogenic toxicity of 6.67E-04 kg 1,4-DCB/kWh and 1.48E-02 kg 1,4-DCB/kWh, respectively and fine particulate matter formation of 3.96E-05 kg PM 2.5 eq/kWh assuming a lifetime of 25 years for these modules. CIGS follows CdTe in almost every environmental impact category.

Base-Stabilized Gallium Sulfides and Selenides Supported by a Bis(oxazolinyl)(phenyl)methanide Ligand.

Gallylene supported by a bis(oxazolinyl)(phenyl)methanide (Boxm) ligand was synthesized and structurally characterized. The reaction of this gallylene with triphenylphosphine sulfide/selenide yielded dimeric gallium sulfide and selenide. These compounds could be converted to monomeric terminal sulfide and selenide by coordination of an external Lewis base such as an N-heterocyclic carbene (NHC or IMe4) and 4-dimethylaminopyridiene (DMAP). These doubly-base-stabilized gallium sulfide/selenide reacted with phenyl isocyanate to give the corresponding cycloadducts by releasing the Lewis base, indicating the formation of a single-base-stabilized gallium sulfide/selenide intermediate.

Development of surface plasmon resonance sensor utilizing GaSe and WS2 for ultra-sensitive early detection of dengue virus

This manuscript introduces highly sensitive surface plasmon resonance (SPR) sensor for early detection of the dengue virus. Through extensive optimization using MATLAB, the sensor architecture is meticulously constructed with a BK7 prism, Copper (Cu) layer, Gallium selenide (GaSe), Tungsten disulphide (WS2), and a sensing medium (SM) containing blood components (infected platelets and normal platelets) to ensure optimal performance. Use of WS2 emerges as a highly effective biomolecular recognition element (BRE) layer, leading to exceptional sensor capabilities. The proposed sensor achieves a peak sensitivity (S) of 303.28 (˚/RIU) and a resonance angle shift (∆θres.) of 10˚ specifically during the detection of infected platelets. Computational modeling using COMSOL Multiphysics validates the ability of the sensor to generate an intense electric field with a magnitude of 1.68×105 (V/m) and a penetration depth (PD) extending to 153.24 nm in the SM. This unique combination of PD and enhanced performance parameters positions the proposed SPR biosensor as a promising tool for the early-stage detection of the dengue virus.

Improving the Selection of PV Modules and Batteries for Off-Grid PV Installations Using a Decision Support System

In the context of isolated photovoltaic (PV) installations, selecting the optimal combination of modules and batteries is crucial for ensuring efficient and reliable energy supply. This paper presents a Decision Support System (DSS) designed to aid in the selection process of the development of new PV isolated installations. Two different multi-criteria decision-making (MCDM) approaches are employed and compared: AHP (Analytic Hierarchy Process) combined with TOPSIS (technique for order of preference by similarity to ideal solution) and Entropy combined with TOPSIS. AHP and Entropy are used to weight the technical and economic criteria considered, and TOPSIS ranks the alternatives. A comparative analysis of the AHP + TOPSIS and Entropy + TOPSIS methods was conducted to determine their effectiveness and applicability in real-world scenarios. The results show that AHP and Entropy produce contrasting criteria weights, yet TOPSIS converges on similar top-ranked alternatives using either set of weights, with the combination of lithium-ion batteries with the copper indium gallium selenide PV module as optimal. AHP allows for the incorporation of expert subjectivity, prioritising costs and an energy yield intuitive to PV projects. Entropy’s objectivity elevates criteria with limited data variability, potentially misrepresenting their true significance. Despite these discrepancies, this study highlights the practical implications of using structured decision support methodologies in optimising renewable energy systems. Even though the proposed methodology is applied to a PV isolated system, it can effectively support decision making for optimising other stand-alone or grid-connected installations, contributing to the advancement of sustainable energy solutions.

Process of solvothermal CZTS nanomaterial for application of solar cell

Sustainable technological development is always associated with usage of energy. Development is directly proportional to utilization of energy. Therefore, energy crisis is one of the crucial issue encounters to mankind during their growth and development of technology. Recent years, researchers comprising many materials like Copper Indium Selenide, Copper Indium Sulfide, Copper Indium Gallium Selenide, Cadmium Telluride and many more. But these all materials are accompanying high cost, lack of abundant sources and toxicity. Hence, thinking about low cost featuring and nontoxicity to overcome energy crisis, Copper Zinc Tin Sulfide (CZTS) is considered as one of the best alternatives in semiconductor solar cell. There are various methods to synthesized CZTS materials, which requires high-cost set ups and equipment. In this paper we have used low-cost synthesis process. CZTS nanomaterials were synthesized in non-aqueous solution with the help of solvothermal method. Synthesis of CZTS nanomaterial was carried out by using Teflon Lined Autoclave in furnace. Further thin films of CZTS material. Further, films were characterized scientifically with the help of UV–VIS spectroscopy, X-ray diffraction, Scanning electron microscopy and potentiometer. CZTS material further annealed at 400 °C for 10 min with which we have observed annealing effect on it. Due to annealing, properties like crystallinity, absorptions and morphology were improved which may be benefitted for progress of efficiency solar cells.

Impact of solar cell materials on the energy performance of SPVT air collector

The impact of roof-integrated semitransparent photovoltaic thermal (SPVT) air collectors connected in series for cold climates has been assessed using a new model established in this research. Numerical calculations have been performed using analytical formulae derived for the temperatures of the room air, roof, and solar cells. These findings have led to evaluations of the thermal, electrical, and overall exergy of various solar cell materials (Single-crystalline, Multi-crystalline silicon, Nanocrystalline -Silicon, Amorphous silicon, Cadmium Telluride and copper indium gallium selenide). According to the findings, amorphous silicon has the maximum peak solar cell electrical efficiency of 10.8 % and single-crystalline has the minimum peak efficiency of 7.0 % for the proposed system. Further, performance analysis has also been done based on different packing factor and mass flow rates.

Cesium Modulation in Cu(In, Ga)(S, Se)2 Solar Cells: Comprehensive Analysis on Interface, Surface, and Grain Boundary.

Cesium (Cs) incorporation and sulfurization on copper indium gallium selenide solar cells are the keys to improving the device quality. In this study, we explore the impact of Cs modulation on sulfur-containing Cu(In, Ga)(S, Se)2 (CIGSSe) absorbers, resulting in a performance increase of over 2%, reaching 18.11%. The improvement stems from a widened surface bandgap, grain boundary (GB) passivation, and a moderate injection blocking layer. The surface bandgap widens from 1.44 to 2.63 eV after Cs incorporation, confirmed by ultraviolet photoelectron spectroscopy (UPS) and low-energy inverse photoemission spectroscopy (LEIPS) analysis. Cs presence and S depletion in GBs suggest a new phase that might mitigate carrier recombination. Heightened Cs incorporation introduces interface issues, including an augmented injection blocking layer and interface defects. Our study offers insights into interface challenges and GB engineering strategies in Cs-treated CIGSSe solar cells, illuminating the multifaceted impact of heavy alkali metal ion Cs in CIGS-based photovoltaics.

Theoretical Understanding of the Structure–Property Relationship of Oxygen-Doped Gallium Selenide as an Efficient Photocatalyst for Oxygen Evolution Reaction

Theoretical Understanding of the Structure–Property Relationship of Oxygen-Doped Gallium Selenide as an Efficient Photocatalyst for Oxygen Evolution Reaction

High‐Performance Perovskite‐Based Tandem Solar Cells: Recent Advancement, Challenges, and Steps toward Industrialization

As a result of an ongoing global dedication, metal‐halide perovskite (PVSK) has proven to be a promising substitute among other developed materials for next‐generation photovoltaic cells due to significantly high efficiency, economical reasons, environmentally friendly processing, and bandgap alterations. In just 12 years, PVSK‐based single cells have achieved an efficiency of 26.1%, reaching single‐crystal silicon solar cells at 27.6% and silicon heterostructure solar cells at 26.8%. PVSK‐based tandem cells also have achieved remarkable attention as a viable candidate for future‐generation photovoltaic technology. Currently, a considerable number of reports are documented as evidence of the efforts to integrate the wide‐bandgap PVSK either with itself (narrow‐bandgap PVSK ([NBG‐PVSK]) or other traditional (NBG) cells, including silicon (Si), copper–indium–gallium–selenide, organic solar cells, cadmium telluride (CdTe), and dye‐sensitized. Thanks to the substantial growth made in the advances of PVSK‐based tandem cells both in the laboratories and in the commercialization sector, this review will systematically elucidate the emergence of PVSK‐based cells, their current status, and applications in tandem configurations. Furthermore, this survey will cover the analysis of different strategies and efforts to achieve cutting‐edge photovoltaic technology. Finally, the commercialization of different PVSK‐based tandem technologies and their prospects are analyzed.

Structural properties and vibrational modes of different polytypes of gallium selenide crystals (ε, β, γ, δ): insights from a DFT study

Structural properties and vibrational modes of different polytypes of gallium selenide crystals (ε, β, γ, δ): insights from a DFT study

Energy band engineering in GaS/InS and GaSe/InS van der Waals bilayers by interlayer stacking design and applied vertical electric field - An ab-initio theoretical calculation based approach

In this work, for the first time, an extensive theoretical investigation of the structural and electronic properties of the van der Waals (vdW) bilayer heterostructures of two-dimensional (2D) Gallium Sulphide (GaS)/Indium Sulphide (InS) and Gallium Selenide (GaSe)/Indium Sulphide (InS), is performed using density functional theory calculation. In this context, the effects of natural and artificial interlayer stacking configurations, and externally applied out-of-plane direction electric field are emphasized. The structural, thermal, and dynamic stabilities of individual bilayers are assessed from the cohesive energy/interlayer interaction energy, phonon spectrum, and molecular dynamics evolution, respectively. The effects of the vdW bilayer environment on the in-plane structural parameters like lattice vector, bond length, and bond angle of the constituent monolayers are comprehensively investigated. The electronic properties are estimated from the band edge energy, the density of states, energy bandgap, and interlayer energy band alignment, which are systematically analysed from the interlayer interactions in terms of interlayer distance, out-of-plane charge distribution, and interlayer charge transfer. The key findings demonstrate that the interlayer stacking engineering and applied out-of-plane electric field can induce unique and tailor-made modulations in the overall electronic properties of GaS/InS and GaSe/InS bilayer, which can be exploited in favour of electronic/optoelectronic applications.