Copper Gallium Research Articles

Comprehensive evaluation of recombination confined performance of CuGaO2 for solar cell application

In the quest to find an outstanding solar energy capturing system that meets requirements like affordability, widespread availability, eco-friendliness, remarkable efficiency, and enduring stability, thorough investigations have been carried out to explore the possibilities presented by ‘Delafossite’ copper gallium oxide (CuGaO2). β-CuGaO2 has an ideal bandgap of 1.5 eV, along with a high absorption coefficient and excellent carrier mobility, making it well-suited for high-efficiency solar cell applications. Theoretical modelling, utilizing the optical and electrical attributes of the CuGaO2 (CGO) material, is employed to analyze its photovoltaic performance when used as an absorber. The detailed balance analysis showed 56.9% of the incident power is wasted in spectrum loss (as thermalisation and non-absorption loss), 10.1% is wasted in intrinsic losses (such as radiative recombination, radiation dilution, entropy generation etc,), extrinsic recombination (originating from electrical losses, parasitic resistance, finite mobility, surface recombination velocity (SRV), non-ohmic contacts etc), eats up another 9.5% and the resultant 23.6% is available as net useful efficiency. Through the careful selection of a suitable buffer counterpart and optimization of material parameters, absorber thickness, defect density, contacts, and SRV, the CGO device dem onstrates an efficiency of 23.6%.

High-performance of low temperature solution-processed P-channel CuGaO thin film transistors

The exploration of p-type metal-oxide semiconductors (MOS) has garnered growing interest, particularly for their potential applications in next-generation optoelectronic devices, display backplanes, and low-power consumption complementary MOS (CMOS) circuits. Here, we introduced low-temperature solution-processed copper gallium oxide (CuGaO) films for p-channel thin-film transistors (TFTs). Hall Effect measurements confirmed the p-type conduction of CuGaO, revealing a conductivity and mobility of 3.76 ×10−2 S/cm and 7.89 cm2V–1s–1, respectively. The p-channel CuGaO-250 TFT demonstrated a field-effect mobility (μFE) of 1.24 cm2V–1s–1, the lowest subthreshold swing (SS) of 519 mV/dec, and an ON/OFF current ratio (ION/IOFF) of ∼104 at a low operating voltage. The notable improvement in TFT performance can be attributed to the quality of the CuGaO-250 film, a smooth surface morphology, and a reduction of interfacial traps between the semiconductor and the gate insulator. Hence, low-temperature fabrication of the p-channel CuGaO TFT holds promise for implementing metal oxide-based TFT and complementary metal oxide semiconductor (CMOS) circuits in next-generation displays.

An investigation of the influence of various factors on the electrical performance of a (CuGaS2) -based thin-film solar cell using SCAPS-1D software

Applying photovoltaics to harvest solar energy is in high demand at the global level. In this study, the modeling tool SCAPS-1D is used to design the cell structure with indium sulfide as a buffer layer, Copper gallium sulfide (CuGaS2) semiconductor compound as the absorber layer, and un-doped and n-doped zinc oxide as the window layer. This study aims to establish an optimal absorber and buffer layer thickness for CuGaS2 thin film solar cells. Among three-generation solar cells, copper gallium sulfide-based photovoltaic cells have grown wider. Indium sulphide is a novel film absorber with good physical characteristics and a band gap energy of 2.4 eV. CuGaS2 thin film performance with various buffer and absorber layer thicknesses for solar cell applications is numerically modeled. This work obtained a thickness range of 50–125 nm and 1000–5000 nm for the buffer and absorber layers, respectively. It also founds an ideal PV system with an efficiency of 10.09% (JSC = 5.30 mA/cm2, VOC = 2.88 V and FF = 67.09%). These modeling results will provide some essential guidelines for making more effective CuGaS2 based solar cells.

STRUCTURAL, ELECTRONIC AND MAGNETIC PROPERTIES OF VANADIUM DOPED DELAFOSSITE CUGAO2: AN AB INITIO STUDY

Delafossite copper gallium oxide (CuGaO2) is one of the most important copper-based delafossite materials reported. It has variety of applications that include but are not limited to; photo catalysis, dye-sensitized solar cells. However, due to the wide band gap of this material, it appears very attractive as transparent conductive oxide (TCO). Thus, it is very important and applicable in optoelectronic device technologies. In this paper, the structural, electronic and magnetic properties of vanadium (V) doped delafossite CuGaO2 are investigated using first principle study based on density functional theory (DFT) as implemented in the QUANTUM ESPRESSO simulation package. We used Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) exchange-correlation scheme for the undoped and vanadium (V) doped structures. There is no structural transition after the doping. The results indicated that the V doping reduced the band gap of the undoped delafossite CuGaO2 by 0.8 eV. It also contributed more to the conduction band states. However, our results also revealed that the 50 % V doping induced significant changes to the magnetic properties of the undoped CuGaO2. It was found that the undoped CuGaO2 is slightly paramagnetic similar to the same group member CuAlO2, whereas the V doped CuGaO2 system is slightly ferromagnetic. This result is in agreement with previous literature concerning the effect of doping semiconductor material with magnetic metals. Thus, based on our results, V doped CuGaO2 material may be considered as an important candidate for spintronics and other related applications.

Development of Sub‐Band in Spray‐Deposited Cr‐Substituted Chalcopyrite Thin Films for Advancing Solar Cell Efficiency

Designing effective strategies for mitigating energy crisis highlights a research gap in current solar cell technologies. This study explores the inherent physicochemical properties of thin films composed of copper gallium sulfide telluride (CuGa1−xCrx(S,Te)2) with chromium substitution, prepared through the chemical spray pyrolysis technique. The investigation showcases how the concept of intermediate band structuring contributes to enhancing solar cell efficiency. This enhancement can be attributed to the remarkable mobility (from 1.80 to 5.48 cm2 V−1 s−1) and conductivity (from 1.00 to 6.06 S cm−1) exhibited by pure and 0.1 chromium thin films, respectively. Notably, the Cr‐0.1‐substituted CGST film displays maximum photoresponsivity of 0.624 AW−1, an external quantum efficiency of 145%, and a detectivity of 2.37E10. The fabricated solar cell is subjected to theoretical simulation using solar cell capacitance simulator‐1D software, revealing an upward trend in efficiency from 7.13% to 11.23% with increasing Cr substitution from 0.025 to 0.1. This efficiency improvement can be ascribed to the reduction in bandgap (from 2.40 to 1.72 eV) and the creation of a sub‐band in CGST due to Cr incorporation, as substantiated by UV–vis and NIR spectroscopy. These outcomes suggest that Cr‐0.1‐substituted CGST holds promise as a potential thin film absorber material in solar photovoltaics.

Preparation and characterization of pristine and Sn doped copper gallium sulphide (CGS) thin films using spray pyrolysis technique

With thin film solar cell applications, chalcopyrite semiconductors present enormous potential for usage as an absorber layer. In today's electronics sector, wide band gap semiconductors have extreme demand for applications such as high-power, high-frequency, challenging devices that are resistant to high temperatures, optoelectronic devices, and short-wavelength light-emitting devices. The undoped and tin-doped CGS thin films are the subject of the current investigation. Pure and Tin (Sn) doped CGS thin films were produced on a glass substrate using a low-cost chemical spray pyrolysis technique in a nitrogen atmosphere. Spray pyrolysis is a flexible and efficient method for thin-film deposition. The process parameters, such as the nozzle distance, spray time, spray rate, and temperature, have a significant impact on the films' quality and characteristics. Fundamental characterization techniques, including XRD analysis, Micro Raman analysis, EDAX, UV-VIS-NIR spectroscopy, and Scanning Electron Microscopy (SEM), were used to examine the generated pristine and Sn-doped CGS thin films. The XRD patterns showed that the pristine and Sn-doped CGS thin films exhibit a tetragonal phase and there is a decrease in the crystallite size with increasing dopant concentration. SEM studies revealed that there is a change in the grain size and surface morphology of the film with increasing Sn doping concentration. The presence of copper (Cu), gallium (Ga), sulfur (S), and Sn was further confirmed by studying the EDAX spectrum. SEM results indicate that the surface morphology of the CGS films is modified by Sn doping. Further increasing the dopant percentage caused deformation and fragmentation of the sample. A comparison of the Raman spectra for pristine and Sn-doped CGS revealed that there is some substantial change in the layer composition after adding the dopant. Compared to the pristine CGS, the peak positions of CGS (1 wt %) and CGS (3 wt %) are not shifted but there is a significant change in the relative peak intensities and formation of an additional peak The Sn-doped CuGaS2 thin films had optical band gaps of 2.47 eV (0.0 wt% Sn-doped), 2.33 eV (1 wt% Sn-doped), and 2.58 eV (3 wt% Sn-doped). From this study, we can say that the 1 wt% Sn doped CGS sample is the best for solar cell application. The XRD results indicated that the Sn dopant addition in the CuGaS2 lattice site does not affect the symmetry of the material. Enhancement of absorption is done by the Sn dopant.

Optimisation and numerical analysis of highly efficient CGSe-based thin film solar cell

Among the various chalcopyrites compounds used in photovoltaic devices, Copper Gallium Selenium (CGSe) turns out as an underperformer due to its limited photovoltaic performance, So far highest efficiency measured is about 11.9%. This paper investigates the possibilities for efficiency enhancement for the CuGSe layer in Cu2O/CGSe/TiO2/ZnO thin film solar cell structure using the SCAPS-1D simulation program. The short circuit current (Jsc) and power conversion efficiency (PCE) is 30.77 mA cm−2 and 27.10%, with open-circuit voltage (Voc) and fill factor (FF) of 1.03 V and 84.72% respectively. Furthermore, we evaluated some specific parameters of TiO2/CGSe heterostructure, such as the influence of layer thickness, operating temperature, the effect of defect density and acceptor density of CGSe layer, metal work function, and the effect of series and shunt resistance on cell performance. We investigated that combining TiO2 as an ETL and Cu2O as HTL with a CGSe absorber layer is novel and promising, which results in higher power conversation efficiency and improves other PV parameters. The application of CGSe/TiO2 heterojunction in a simulated model offers a viable method for the development of high-efficiency solar cell devices.

Scrutinizing the effect of substrate temperature and enhancing the multifunctional attributes of spray deposited copper gallium sulfide (CuGaS2) thin films

ABSTRACT Polycrystalline chalcopyrite CuGaS2 thin films were prepared using a spray pyrolysis route has been considered a potential material for the solar cell absorber layer. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) studied the impact of substrate temperature in the range of 200–300˚C on surface profile and roughness. Powder X-ray diffraction disclosed that the films were polycrystalline at all examined substrate temperatures, with crystallite size increasing with increased substrate temperature. The UV-Vis displays the cut-off wavelength in 550–880 nm for varied substrate temperatures of CuGaS2 thin films, and the observed band gap is 2.75 eV–1.89 eV. The electrical attributes showed the enhancement in mobility (4.632 cm2 V−1 s−1) for varied substrate temperatures of CuGaS2 thin films. The 300˚C temperature sprayed CuGaS2 polycrystalline films are a decent candidate to be apposite as an absorber layer in thin film photovoltaic solar cells.

Hybrid biological/inorganic photocathode for H2 production based on a NiFeSe hydrogenase immobilized on electrodeposited CuGaS2

In order to mitigate global warming and pollution problems, new energy vectors need to be developed towards a fossil fuel-free society. Hydrogen is a great candidate for the role, since it can be cleanly obtained from water splitting. However, finding an efficient method that allows diminishing the high potentials required for the reaction is still a challenge to overcome. In order to tackle this task, a combination of a redox biocatalyst and an inorganic semiconductor that harnesses sunlight to enhance the H2 photoelectrochemical production has been studied. For this endeavor, we have developed a photocathode based on the p-type semiconductor copper gallium sulfide and the Desulfovibrio vulgaris Hildenborough NiFeSe-hydrogenase where the photoexcited semiconductor transfers excited electrons to the enzyme upon visible irradiation. The system is capable of producing photoelectrochemical biocatalytic proton reduction to H2 without any sacrificial agent while providing an approximately 400 mV decrease of the applied potential.

Conversion efficiency improvement of CGS/CIGS photovoltaic cell

A novel multi-junction CGS/CIGS solar cell is proposed in this paper. Two p-n junctions of the presented solar cell are copper gallium diselenide (CGS) and copper indium gallium diselenide (CIGS). Three anti-reflector coating layers are embedded at the top of the structure. The anti-reflector layers are cadmium sulfide (CdS), zinc telluride (ZnTe), and zinc oxide (ZnO), respectively. These layers are optimized so that the short-circuit currents of the sub-cells be equal. The optimization method is performed by adjusting the structural and physical parameters of the layers so that the conversion efficiency is increased. The open-circuit voltage (Voc) equal to 2.14 volt, short-circuit current density (Jsc) of 25.1735 mA/cm2, fill factor (FF) of 86.88%, and conversion efficiency of 46.802% are obtained by designed solar cell. Moreover, the output characteristics of the designed structure are extracted by considering the temperature variations. Finally, the Jsc of the cell is improved by about 2.5907 mA/cm2 after adding an Aluminium back mirror layer at the bottom surface. An optimized efficiency of 47.437% is achieved using this method.

A Novel Approach for Designing a Sub-Bandgap in CuGa(S,Te)2 Thin Films Assisted with Numerical Simulation of Solar Cell Devices for Photovoltaic Application.

As a well-explored chalcopyrite material, copper gallium sulfide CGS has been considered a potential material for solar cell absorber layers. However, its photovoltaic attributes still require to be improved. In this research, a novel chalcopyrite material, copper gallium sulfide telluride CGST, has been deposited and verified as a thin film absorber layer to fabricate high-efficiency solar cells by experimental testing and numerical simulations. The results display the intermediate band formation in CGST with incorporation of Fe ions. Electrical studies showed enhancement in mobility from 1.181 to 1.473 cm2 V-1 s-1 and conductivity from 2.182 to 5.952 S cm-1 for pure and 0.08 Fe-substituted thin films. The I-V curves display the photoresponse and ohmic nature of the deposited thin films, and the maximum photoresponsivity (0.109 A W-1) was observed for 0.08 Fe-substituted films. Theoretical simulation of the prepared solar cells was carried out using SCAPS-1D software, and the obtained efficiency displayed an increasing trend from 6.14 to 11.07% as the Fe concentration increased from 0.0 to 0.08. This variation in efficiency is attributed to the decrease in bandgap (2.51-1.94 eV) and the formation of an intermediate band in CGST with Fe substitution, which is evidenced in UV-vis spectroscopy. The above revealed results open the way to 0.08 Fe-substituted CGST as a promising candidate as a thin film absorber layer in solar photovoltaic technology.

Effect of temperature and improving the optoelectrical attributes of copper gallium sulfide (CuGaS2) thin films

ABSTRACT This work is focused on the optimization and characterization of copper gallium sulfide (CuGaS2) thin film prepared via the spray pyrolysis route. Chalcogenides are compounds having a chalcogen anion and an electropositive element, and these thin films have more absorption coefficients. The structural, optical, electrical, and morphological properties of CuGaS2 thin films are studied using X-ray diffraction (XRD), Scanning electron microscopy (SEM), UV-Vis-NIR Spectroscopy, and Hall effect techniques. The above characteristics are studied for both as prepared and annealed Copper Gallium Sulfide (CGS) thin films. These films have a chalcopyrite tetragonal crystal structure. It is a promising material for solar cell applications due to its suitable bandgap and good electrical stability. The results of this study provide a framework for fabricating an optimized CGS absorber layer in photovoltaic solar cells.

Photochemically-Activated p-Type CuGaO2 Thin Films for Highly-Stable Room-Temperature Gas Sensors

The photochemical activation process is a promising way to operate metal oxide gas sensors at room temperature. However, this technique is only used in n-type semiconductors. In this study, we report a highly stable p-type copper gallium oxide (CuGaO2) gas sensor fabricated through the facile sol-gel process. The sensor is capable of detecting O3 gas at room temperature, and its gas response can be further enhanced by ultraviolet (UV) activation. The highest gas response of 7.12 to 5 ppm O3 gas at a UV intensity of 10 mW cm−2 is achieved at room-temperature. In addition, the CuGaO2 sensor shows excellent long-term stability, with a degradation of approximately 3% over 90 days. These results strongly support the solution-processed CuGaO2 as a good candidate for room-temperature gas sensors.

Numerical modeling of CuSbSe2-based dual-heterojunction thin film solar cell with CGS back surface layer

Ternary chalcostibite copper antimony selenide (CuSbSe2) can be a potential absorber for succeeding thin film solar cells due to its non-toxic nature, earth-abundance, low-cost fabrication technique, optimum bandgap, and high optical absorption coefficient. The power conversion efficiencies (PCEs) in conventional single heterojunction CuSbSe2 solar cells suffer from higher recombination rate at the interfaces and the presence of a Schottky barrier at the back contact. In this study, we propose a dual-heterojunction n-ZnSe/p-CuSbSe2/p+-copper gallium selenide (CGS) solar device, having CGS as the back surface field (BSF) layer. The BSF layer absorbs low energy (sub-bandgap) light through a tail-states-assisted upconversion technique, leading to enhanced conversion efficiency. Numerical simulations were run in Solar Cell Capacitance Simulator-1 dimensional software to examine how the performance of the proposed solar cell would respond under different conditions of absorber layer thickness, doping levels, and defect densities. The simulation results exhibit a PCE as high as 43.77% for the dual-heterojunction solar cell as compared to 27.74% for the single heterojunction n-ZnSe/p-CuSbSe2 counterpart, demonstrating the capability of approaching the detailed balance efficiency limit calculated by Shockley–Queisser.

Hierarchically structured sub-bands in chalcopyrite thin-film solar cell devices

The study utilizes the inherent physiochemical properties of vanadium-incorporated copper gallium sulfide telluride (CuGa1−xVx(S,Te)2) thin films deposited via a chemical spray pyrolysis route and evokes how the art of intermediate band structuring favours the solar cell efficiency.

Preparation and Characterization of p-Type Copper Gallium Oxide (CuGaO2) Thin Films by Dual Sputtering Using Cu and Ga2O3 Targets

For the first time, this research focuses on the deposition and characterization of radio frequency (RF) sputtered p-type CuGaO2 thin films using the dual-target sputtering technique with Cu and Ga2O3 targets. The sputtering power to the Cu target was varied from 5 W to 50 W while having the Ga2O3 sputtering power constant at 200 W. The deposited films were subsequently annealed at two different annealing temperatures of 800 °C and 900 °C in N2 ambiance. The effects of variation in Cu sputtering power and annealing temperature on structural, optical, and electrical properties of CuGaO2 thin films are reported in this work. Single-phase CuGaO2 was confirmed in films deposited with Cu sputtering power of 25 W by XRD analysis. XPS analysis revealed a near stoichiometric composition ratio of Cu:Ga in films deposited with Cu sputtering power of 25 W. The optical studies were performed in 200 nm–800 nm wavelengths on all the post-deposition annealed films. The optical transmission was found to decrease with an increase in Cu sputtering power. The optical bandgap was found to be between 3.3 and 4.6 eV. Single-phase CuGaO2 film was p-type with a resistivity of 60 Ω-cm. This resistivity value is one of the lowest ever reported values identified from CuGaO2 thin films.

Innovative and sustainable separation and recovery of valuable metals in spent CIGS materials

In recent years, the rapid development of copper indium gallium selenide (GIGS) solar cells makes it necessary to recycle spent CIGS in order to realize circular economy. In this work, a novel and efficient method for comprehensive recovery valuable metals in spent CIGS materials was investigated, mainly including three steps: (1) leaching of spent CIGS with nitric acid to separate indium; (2) precipitating to obtain copper gallium selenite mixture with magnesium oxide as precipitant; (3) calcination of the residue and the precipitation to recover selenium. X-ray photoelectron spectroscopy (XPS) analysis indicates that the valence state of selenium was converted from negative divalent to positive tetravalent after oxidative leaching. In addition, the results of X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR) and scanning electron microscope/energy dispersive spectrometer (SEM/EDS) shows that the dissolution of metals in CIGS during leaching were significantly different. Copper and gallium were almost completely leached, while indium entered the slag phase as indium selenite, which achieved the separation of indium. Moreover, the reaction mechanism of leaching was analyzed from the perspective of thermodynamics. After leaching, copper, gallium and selenium can be completely recovered from the leach liquor using magnesium oxide as precipitant. Subsequently, the separation of Se in the residue and precipitates can be achieved at 800 °C for 90 min. Finally, the recovery yields of Cu, In, Ga and Se were 99.23%, 96.82, 98.08% and 96.38% respectively. This research represents an important innovation from the perspective of circular economy and provides a new idea for comprehensive utilization of secondary solar cells.

Preparation and Characterization of Radio Frequency Sputtered Delafossite p-type Copper Gallium Oxide (p-CuGaO2) Thin Films

In this research, CuGaO2 thin films were prepared on quartz substrates by radio frequency magnetron sputtering technique at 400 °C followed by subsequent annealing in N2 ambiance. The effects of annealing temperature on structural, morphological, optical, and electrical properties of CuGaO2 thin films are reported in this work. X-ray Diffraction (XRD) analysis confirmed the presence of single-phase CuGaO2 in the film annealed at 900 °C. Near stoichiometric composition ratio of Cu:Ga (1:1.08) was identified in the film annealed at 900 °C. The Field Emission Scanning Electron Microscope (FESEM) images showed an increase in the grain size with an increase in annealing temperature. A UV–V is spectrophotometer was used to perform optical studies in the 200–800 nm wavelength region on all films. The optical bandgap was calculated from the transmission studies and was found to be in the range of 2.77 to 3.43 eV. The films annealed at temperatures 800 °C and above were found to be p-type. The lowest resistivity value of 230 Ω-cm was achieved in the film annealed at 900 °C.

One-electron bonds in copper-aluminum and copper-gallium complexes.

Odd-electron bonds have unique electronic structures and are often encountered as transiently stable, homonuclear species. In this study, a pair of copper complexes supported by Group 13 metalloligands, M[N((o-C6H4)NCH2PiPr2)3] (M = Al or Ga), featuring two-center/one-electron (2c/1e) σ-bonds were synthesized by one-electron reduction of the corresponding Cu(i) ⇢ M(III) counterparts. The copper bimetallic complexes were investigated by X-ray diffraction, cyclic voltammetry, electron paramagnetic spectroscopy, and density functional theory calculations. The combined experimental and theoretical data corroborate that the unpaired spin is delocalized across Cu, M, and ancillary atoms, and the singly occupied molecular orbital (SOMO) corresponds to a σ-(Cu–M) bond involving the Cu 4pz and M ns/npz atomic orbitals. Collectively, the data suggest the covalent nature of these interactions, which represent the first examples of odd-electron σ-bonds for the heavier Group 13 elements Al and Ga.

Simulation approach to reach the SQ limit in CIGS-based dual-heterojunction solar cell

In this article, we demonstrate the design and simulation of a copper indium gallium diselenide (CIGS)-based highly-efficient n-CdS/p-CIGS/p+-CGS dual-heterojunction (DH) solar cell. The simulation has been performed using SCAPS-1D software with reported experimental physical parameters. The simulated efficiency of our proposed solar cell arises to 47% with open circuit voltage, VOC = 0.98 V, short circuit current density, JSC = 59.94 mA/cm2 and fill factor, FF = 80.07%, respectively. Such a high short circuit current and corresponding elevated efficiency are predominantly originated from the longer wavelength absorption of photons through a tail-states-assisted (TSA) two-step upconversion in the copper gallium diselenide (CGS) Back surface field (BSF) layer of the DH solar cells. The suggested method numerically approaches the Shockley-Queisser (SQ) detailed balance limit, providing a possible opportunity of enhancing existing photovoltaic (PV) parameters to the researchers as well as manufacturers.