Predicting the stable rhodium based chalcopyrites with remarkable optical properties (original) (raw)
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Thin Solid Films, 2008
The optical properties of a novel potential high-efficiency photovoltaic material have been studied. This material is based on a chalcopyritetype semiconductor (CuGaSa) with some Ga atom substituted by Ti and is characterized by the formation of an isolated transition-metal band between the valence band and the conduction band. We present a study in which ab-initio density functional theory calculations within the generalized gradient approximation are carried out to determine the optical reflectivity and absorption coefficient of the materials of interest. Calculations for the host semiconductor are in good agreement with experimental results within the limitations of the approach. We find, as desired, that because of the intermediate band, the new Ti-substituted material would be able to absorb photons of energy lower than the band-gap of the host chalcopyrite. We also analyze the partial contributions to the main peaks of its spectrum.
Electronic and Optical Modeling of Solar Cell Compounds CuGaSe2 and CuInSe2
Journal of Electronic Materials, 2011
We present dielectric-function-related optical properties such as absorption coefficient, refractive index, and reflectivity of the semiconducting chalcopyrites CuGaSe2 and CuInSe2. The optical properties were calculated in the framework of density functional theory (DFT) using linear combination of atomic orbitals (LCAO) and full-potential linearized augmented plane wave (FP-LAPW) methods. The calculated spectral dependence of complex dielectric functions is interpreted in terms of interband transitions within energy bands of both chalcopyrites; for example, the lowest energy peak in the \varepsilon2 (ω ) spectra for CuGaSe2 corresponds to interband transitions from Ga/Se-4p → Ga-4s while that for CuInSe2 emerges as due to transition between Se-4p → In-5s bands. The calculated dielectric constant, \varepsilon1 (0) , for CuInSe2 is higher than that of CuGaSe2. The electronic structure of both compounds is reasonably interpreted by the LCAO (DFT) method. The optical properties computed using the FP-LAPW model (with scissor correction) are close to the spectroscopic ellipsometry data available in the literature.
Optik, 2018
Investigation of the physical properties of chalcopyrite materials using ab-initio methods have been carried out to simulate a new structure of thin-films photovoltaic cells with high conversion efficiency. The Density Functional Theory calculations have been performed using Wien2k computational package by employing the full-potential linearized augmented plane wave method. Structural and electronic properties of chalcopyrite semiconducting material Copper-Indium-Gallium-Selenium i.e. CuIn 1-x Ga x Se 2 have been investigated using local density approximation for the exchange-correlation potential. The electronic structures and linear optical properties have been studied using both the semi-local Becke-Johnson potential and its modified form i.e. mBJ and TB-mBJ. Computational results are in good agreement with those acquired experimentally. The viability of alloys in realization of ultra-thin-film based (CIGS) solar cells with high performance has been proposed after simulation and analysis study using one of solar cell simulation tools. The studied material exhibits capability to become a promising candidate for fabrication of optoelectronic and photovoltaic devices. x Ga x Se 2 solar cells. CIGS thin films have been elaborated using different techniques including, selenization of sequentially stacked precursors [8], physical evaporation [9] and rapid thermal process [10]. On the other hand, some theoretical performances are found
Journal of Applied Physics, 2016
Cu-based chalcogenides are promising materials for thin-film solar cells with more than 20% measured cell efficiency. Using first-principles calculations based on density functional theory, the optoelectronic properties of a group of Cu-based chalcogenides Cu2-II-IV-VI4 is studied. They are then screened with the aim of identifying potential absorber materials for photovoltaic applications. The spectroscopic limited maximum efficiency (SLME) introduced by Yu and Zunger is used as a metric for the screening. After constructing the current-voltage curve, the maximum spectroscopydependent power conversion efficiency is calculated from the maximum power output. The role of the nature of the band gap, direct or indirect, and also of the absorptivity of the studied materials on the maximum theoretical power conversion efficiency is studied. Our results show that Cu2II-GeSe4 with II=Cd and Hg, and Cu2-II-SnS4 with II=Cd and Zn have a higher theoretical efficiency compared to the materials currently used as absorber layer.
Thin Solid Films, 2007
Electronic structure calculations are carried out for CuGaS 2 partially substituted with Ti, V, Cr or Mn to ascertain if some of these systems could provide an intermediate band material able to give a high efficiency photovoltaic cell. Trends in electronic level positions are analyzed and more accurate advanced theory levels (exact exchange or Hubbard-type methods) are used in some cases. The Ti-substituted system seems more likely to yield an intermediate band material with the desired properties, and furthermore seems realizable from the thermodynamic point of view, while those with Cr and Mn might give half-metal structures with applications in spintronics.
Thin Solid Films, 2008
In this work, we present frozen phonon and linear response ab-initio research into the vibrational properties of the CuGaS2 chalcopyrite and transition metal substituted (CuGaS2)M alloys. These systems are potential candidates for developing a novel solar-cell material with enhanced optoelectronic properties based in the implementation of the intermediate-band concept. We have previously carried out ab-initio calculations of the electronic properties of these kinds of chalcopyrite metal alloys showing a narrow transition metal band isolated in the semiconductor band gap. The substitutes used in the present work are the 3d metal elements, Titanium and Chromium. For the theoretical calculations we use standard density functional theory at local density and generalized gradient approximation levels. We found that the optical phonon branches of the transition metal chalcopyrite, are very sensitive to the specific bonding geometry and small changes in the transition metal environment.
A Few Prospective Compositions for the Chalcogenide Photovoltaics
The intensive effort has made to design new amorphous chalcogenide alloy for the photovoltaic as well as other optoelectronics applications. This work describes a short over view on photovoltaic materials, the relevance of inorganic photovoltaic materials, the development history of Cu (InGa) Se (CIGS) photovoltaics, prospects of chalcogenide photovoltaics. Along with the successful synthesis of Cu20(In14Ga9)Se45Te12 (CIGST-1) and Cu25(In16Ga9)Se40Te10 (CIGST-2) chalcopyrite materials in amorphous form. Structural analysis of the bulk materials was performed from the X-ray diffraction (XRD), Field Emission Scanning Microscope (FSEM), Differential Thermal Analyzer (DTA) and micro Raman analysis. While, the presence of elemental concentrations has been confirmed from the Energy Dispersive Spectroscopy (EDS). Subsequently, thermally evaporated thin films surface morphology and roughness parameter have been analyzed by using the Atomic Force Microscopy (AFM). The 100nm thin films, current-voltage (I-V) and resistance-voltage (R-V) characteristics at room temperature and in the temperature range upto 200℃, under applied voltage range upto 40 V have also been discussed. Outcomes of the structural analysis demonstrates bulk materials have an overall amorphous structure, and their thermally evaporated deposited thin films have low roughness. Structural analysis also reveal bulk CIGST-2 composition has single phase amorphous structure. This material thin film has a smooth surface morphology with a lower and higher values of I and R at room temperature. While, in the temperature range up to 200℃ it has a higher and lower I and R respectively. The physical variation in these materials could be explained with the help of the chemical bond theory of solids.
New Materials for Intermediate Band Photovoltaic Cells. Theoretical and Experimental Approaches
2010
Density functional theory calculations of certain transition-metal doped semiconductors show a partially occupied relatively narrow band located between valence band and conduction band. These novel systems, containing the metallic band, are called intermediate-band materials. They have enhanced optoelectronic properties which allow an increase in solar energy conversion efficiency of conventional solar cells. We previously proposed III-V, chalcopyrite and sulfide derived compounds showing desirable characteristics to produce the intermediate band of interest inside the band-gap. In order to obtain further intermediate-band material proposals, this work focuses on studing other compounds constituted mainly by tetravalent elements. The first proposal is vanadium substituting Sn atoms in SnS2 , the second one is composed by type II silicon clathrate with two possibilities: vanadium substituting Si and Ag occluded in the intra-crystalline cavities. UV-Vis-NIR spectra of some of these s...
Journal of Physics and Chemistry of Solids, 2005
The amazing opto-electronic properties of pseudo-ternaries Cu(In,Ga)(S,Se) 2 compounds are, for a great deal, related to their defect chemistry, for which ab initio calculation have already provided new insights. As Indium and Gallium are rare and expensive elements, the search of an alternative may become an important issue. Ab initio calculation of energies and electronic structures of various chalcopyrite type structures replacing In by other elements has been performed exploring over 16 compounds with some 10 different elements of the periodic table. Among the different possibilities, the substitution of In by the isoelectronic couples such as (Zn, Sn) and other cationic couples having an average valency of III have been evaluated in details, as well as the influence of the anion (S or Se). The most important point defects and defect complexes have been explored. Low copper vacancy (V Cu ) and defect complexes (such as V Cu CZn Cu ) formation energies have been found in these new compounds: for instance the formation energy of V Cu in Cu 2 SnZnSe 4 is 0.49 eV as compared to 0.48 eV in CuInSe 2 (CIS). In addition to point defect characteristics, different electronic properties (such as band structure, bonding character) are compared to the one of CIS, which is considered as our reference structure. The method used is based on the density functional theory within the framework of pseudo-potentials and plane waves basis. The results are discussed in view of the existing data, models and calculations. Based on these properties as well as the ionic/covalent bonding character some trends are exposed. q
A Deep Outlook for the Chalcopyrite Solar Cells: For Future Perspectives
International Journal of Energy and Power Engineering
This publication investigates to present all new scientific and industrial works all rolled into one with more effective and predictability aspect in chalcopyrite Photovoltaics (PVs). The paper suggests that comprehensive and fine-tuned directions supporting a large portfolio of solar energy materials could be extended to most efficiency, which mostly depend on the growth techniques especially usage rates in substituents and their characteristic/specific properties. There is an indispensable source of solar energy. If this were the case, new energy materials could well become a competitive alternative in many applications within the next few years. This publication builds upon past analyses of chalcopyrites contained in the word Energy outlook as efficient alternative materials. It aims at offering an updated picture of current technology trends/demands/markets, as well as new analyses on how solar energy technologies/materials for capturing the purposed efficiency and durableness can be used in the various energy consuming/developing sectors, now and in the future. In this work we have tried to summarize the all significant studies about Chalcopyrite solar cells from the past to the present and also tried to introduce Te doped CuInGaSeTe compound which is a new member of the family that we produced.