Influence of Cu 2 S, SnS and Cu 2 ZnSnSe 4 on optical properties of Cu 2 ZnSnS 4 (original) (raw)
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A DFT Study of Structure, Electronic and Optical Properties of Se-Doped Kesterite Cu2ZnSnS4 (CZTSSe)
Letters in Applied NanoBioScience, 2023
In this work, we have studied the geometric structure and electronic and optical properties of Cu2ZnSn(S1-xSex)4 nanocrystals where x = 0, 0.25, 0.50, 0.75, 1.00 by the quantum-chemical calculations within the framework of DFT. For the electronic and optical properties calculations, the effective XC functional and the TB-mBJ potential were used. The calculated structural characteristics show that the volume of these systems increases with increasing the Se concentration. The electronic properties of the Se-doped kesterite Cu2ZnSnS4 show that the bandgap tends to decrease. It was found that the Se-doped material has noticeably increased its absorption capacity. Hence, the efficiency of the Cu2ZnSnS4 in the IR region of radiation improves. The effective reduction bandgap from 1.455 eV to 0.94 eV is observed, which is in gоod agreement with known experimental data for the pure and undoped systems Cu2ZnSnS4 and Cu2ZnSnSе4. The calculated band gap is 1.346 eV for the Cu2ZnSnS3Se system, which is comparable with the optimal bandgap of semiconductors used in photovoltaic applications. It was found that with the increase of the Se concentration, the absorption coefficient increases, thereby resulting in the materials' reflectivity decrease. The calculated optoelectronic parameters and the density of electronic states indicate that the Cu2ZnSnS4:Se system possesses a favorable property, suitable for applications in solar cells technology.
THE POST ANNEALED EFFECT ON THE OPTICAL PROPERTIES OF Cu2ZnSnS4 NANOMATERIALS
International Journal on Applied Bio-Engineering, 2015
Cost effective photovoltaic Cu2ZnSnS4 (CZTS) nanomaterials with kesterite crystal phase were synthesized using a facile solvothermal method. Here ethylene glycol was the solvent and Polyvinylpyrrolidone (PVP) used as capping agent. The obtained CZTS nanoparticles were characterized by means of suitable analytical techniques such as X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Raman Spectroscopy, Ultraviolet-Visible (UV-Vis) Spectrometer and Photoluminescence (PL) respectively. The XRD results showed that the obtained sample presented as kesterite crystallinity with (112), (200), (220) and (312) planes of the CZTS nanoparticles and the average crystallite size was about 5.7 nm. The morphological investigation results given by the FESEM revealed that the average particle size of the sample was around 129 to160 nm. In addition, the optical observation suggested by both the absorption of UV-Vis and emission spectra of PL showed that the CZTS nanoparticles produced by this solvothermal method has the direct band gap energy within the range of 1.49 to 1.53 eV, which is near the optimal value and it is a dynamic absorber material for the efficient photovoltaic application.
On the Optical Properties of the Cu2ZnSn[S1−xSex]4 System in the IR Range
TRENDS IN SCIENCES , 2023
Following the recent classification by the European Commission of some elements as critical raw materials (CRM), there is an increasing interest in the development of CRM-free thin film photovoltaic (PV) technologies, including kesterite materials. Moreover, starting with the performance breakthrough reported by IBM in 2010, the efficiency of kesterite-based solar cells steadily progressed in the following years achieving. Therefore, in recent years, there has been a significant research effort to develop kesterite-based devices. However, despite the large number of theoretical and experimental works, many aspects of the problem have not yet been fully studied. Therefore, the issues considered in the article, especially the behavior of the absorption and photoconductivity spectra of the Cu2ZnSn[S1−xSex]4 system, depending on the S/Se ratio, are extremely important and, at the same time, one of the topical and poorly studied problems. In this work, using quantum-chemical calculations in the framework of density functional theory (DFT), we study the optical properties of semiconductor nanocrystals of kesterite Cu2ZnSnS4 doped with Se. Using the WIEN2k package, the concentration dependences of the optical characteristics of nanocrystals of the Cu2ZnSn[S1−xSex]4 system (x = 0.00, 0.25, 0.50, 0.75 and 1.00) were calculated. It is shown that doping with Se at the S position leads to a noticeable improvement in the photoabsorbing properties of these nanocrystals, as well as their photoconductivity in the IR range. The calculated absorption and extinction spectra, as well as the refractive indices and permittivity of the materials under study, are compared with experimental data known from the literature. The data obtained will significantly enrich the existing knowledge about the materials under study and will contribute to the expansion of the field of application of these compounds in optoelectronic devices.
Study of optical and structural properties of Cu2ZnSnS4 thin films
Thin Solid Films, 2011
Cu 2 ZnSnS 4 is a promising semiconductor to be used as absorber in thin film solar cells. In this work, we investigated optical and structural properties of Cu 2 ZnSnS 4 thin films grown by sulphurization of metallic precursors deposited on soda lime glass substrates. The crystalline phases were studied by X-ray diffraction measurements showing the presence of only the Cu 2 ZnSnS 4 phase. The studied films were copper poor and zinc rich as shown by inductively coupled plasma mass spectroscopy. Scanning electron microscopy revealed a good crystallinity and compactness. An absorption coefficient varying between 3 and 4 × 10 4 cm −1 was measured in the energy range between 1.75 and 3.5 eV. The bad gap energy was estimated in 1.51 eV. Photoluminescence spectroscopy showed an asymmetric broad band emission. The dependence of this emission on the excitation power and temperature was investigated and compared to the predictions of the donor-acceptor-type transitions and radiative recombinations in the model of potential fluctuations. Experimental evidence was found to ascribe the observed emission to radiative transitions involving tail states created by potential fluctuations.
International Journal of Applied Power Engineering, 2022
In the present work, using quantum-chemical calculations in the framework of density functional theory (DFT), we study the optical properties of semiconductor nanocrystals of kesterite Cu2ZnSnS4 doped with Se. Using the WIEN2k package, the concentration dependences of the optical characteristics of nanocrystals of the Cu2ZnSnSexS4-x system (x = 0, 1, 2, 3, 4) were calculated. It is shown that doping with Se at the S position leads to a noticeable improvement in the photo absorbing properties of these nanocrystals, as well as their photoconductivity in the IR range. The calculated absorption and extinction spectra of the materials under study, are compared with experimental data known from the literature. The data obtained will significantly enrich the existing knowledge about the materials under study and will help expand the scope of these compounds in optoelectronic devices, especially in solar cells and other devices that convert solar energy into electricity.
In this work we systematically analyze the structural, electronic and optical properties of the Cu 2 ZnSnS 4 and Cu 2 ZnSnSe 4 . We show that kesterite is more stable phase than the stannite phase and the estimated direct band gaps energy for Cu 2 ZnSn(S, Se) 4 compounds ranges from 0.70 to 1.47 eV. Furthermore, defect studies reveal that Cu vacancy is the most dominant vacancy with the lowest formation energy. We find that the vacancy formation energies are larger in the Cu 2 ZnSnS 4 compared with the corresponding vacancies in the Cu 2 ZnSnSe 4 . All the calculations are carried out by employing hybrid functional approach within the density functional theory.
Electronic and Photon Absorber Properties of Cr-Doped Cu2ZnSnS4
The Journal of Physical Chemistry C, 2012
The Cu 2 ZnSnS 4 (CZTS) semiconductor is a potential photovoltaic material due to its optoelectronic properties. These optoelectronic properties can be potentially improved by the insertion of intermediate states into the energy bandgap. We explore this possibility using Cr as an impurity. We carried out first-principles calculations within the density functional theory analyzing three substitutions: Cu, Sn, or Zn by Cr. In all cases, the Cr introduces a deeper band into the host energy bandgap. Depending on the substitution, this band is full, empty, or partially full. The absorption coefficients in the independent-particle approximation have also been obtained. Comparison between the pure and doped host's absorption coefficients shows that this deeper band opens more photon absorption channels and could therefore increase the solar-light absorption with respect to the host.
Electronic Band Structure of Copper Zinc Tin Sulphide (Cu 2 ZnSnS 4).
IOSR Journals , 2019
Cu 2 ZnSnS 4 (CZTS), made entirely of abundant materials, has attracted a great interest due to its potential applications in sustainable thin-film solar cell devices. The electronic band structure of kesterite Cu 2 ZnSnS 4 compound has been calculated using the pseudo-potential method. Projector augmented waves (PAW) within the density functional theory (DFT) was used in all calculations using local density approximation (LDA) for one calculation and inclusion of potential correlation term, U to LDA (i.e LDA + U) in another calculation. The results predicted Cu 2 ZnSnS 4 to be a p-type semiconductor with bandgap value for (1) LDA as 0.039 eV and (2) LDA + U as 1.83 eV. This bandgap value of 1.83 eV is in agreement with experimental results and it confirmed the material as a good absorber layer for solar cells. The density of states (DOS) showed that the conduction band was mainly contributions from Sn-5p and Zn-4s orbitals. It is recommended that the orbital independent term, U be added to LDA during calculations because it improves the bandgap value.