Kesterite thin films of Cu2ZnSnS4 obtained by spray pyrolysis

Thin films of Cu2ZnSnS4 CZTS were deposited using the spray pyrolysis method as relatively fast and vacuum free method. Obtained samples were analyzed using the X Ray Fluorescence, grazing incidence X Ray Diffraction and Raman Spectroscopy techniques. Analysis showed close to stoichiometry composition of the films with kesterite type structure but poor crystalline quality and possible existence of secondary phases. To improve the quality of the films, the as prepared layers were annealed in the presence of elemental Sn and S. Comparison of the results before and after annealing showed a strong improvement of the crystalline quality and a significant reduction of concentration of secondary phases of the films without significant change of composition. The measured optical band gap is equal to 1.52 and 1.55 eV in the as prepared and annealed films, respectively. The optical absorption coefficient is found to be gt; 10 4 cm

AgxCu1 x 2ZnSnS4 thin films prepared by spray pyrolysis

One of the most detrimental problems in the further development of thin film solar cells based on kesterite type compound semiconductors is the limitation in open circuit voltage VOC . The latter, according to many theoretical and experimental studies, is mostly related to the high concentration of intrinsic defects, mainly with ZnCu antisites. Recently, a way for overcoming this problem by partial substitution of Cu cations by Ag was proposed. This may lead to a strong decrease of intrinsic defects due to higher formation energy of ZnAg defects and as result to increase of VOC. Taking this into account, we performed an investigation of AgxCu1 x 2ZnSnS4 thin films deposited by the spray pyrolysis method. The as deposited thin films with 10, 15 and 20 of Ag were annealed at 450 C for 60 min in presence of elemental sulfur. Structural investigations by XRD, as well as Raman spectroscopy studies confirmed the formation of solid solutions. Photoluminescence investigations showed one broad band, which exhibits the blue shift with the increase of Ag concentration. This could be explained by changes in the activation energy of the defect levels involved in radiative transition rather than with the band gap change. Keywords Kesterite, Thin Film, Spray Pyrolysis, XRD, Raman Spectroscop

AgxCu1 x 2ZnSn S,Se 4Thin Films Prepared By Spray Pyrolysis The Influence of the Ag Concentration

Thin films of Ag x Cu 1 x 2 ZnSn S,Se 4 ACZTSSe , with x 0.05 0.20, were deposited using the spray pyrolysis method, with subsequent annealing in S Se atmosphere. Investigation of the chemical composition, structural properties and Raman scattering spectroscopy allowed to conclude that for thin films with up to 15 of Ag concentration there is stable the formation of the solid solutions of ACZTSSe, while in the thin film with 20 Ag strong compositional and phase inhomogeneities were found. Investigation of the electrical transport properties showed their insignificant change with increasing the Ag concentration up to 1

Silicon solar cells based on pSi/nSi3N4 nanolayers

Thin films of Si3N4 were prepared by non-reactive magnetron sputtering in an Ar atmosphere. A previously synthesized Si3N4 was used as a solid-state target. Deposition was carried out on a cold substrate of p-Si (100) with a resistivity of 2 Ohm cm. The Raman spectrum of the deposited Si3N4 layers has been investigated. The position of the maximum in the Raman scattering spectrum of Si3N4 layers corresponds to the Si3N4 compound and the shape of the spectrum is characteristic for the nanocrystalline state of the cubic modification of silicon nitride.The film thickness has been determined from atomic force microscopy measurements. The results of electron diffraction investigations of n-Si3N4 nanolayers with thicknesses up to 20 nm demonstrates that as-deposited Si3N4 thin films consist of a mixture of microcrystalline and amorphous phases.Solar cells based on heterostructures consisting of a p-type Si (100) and n-type Si3N4 nanolayers were fabricated and studied. Keywords: Photovoltaic cells, Heterostructures, Magnetron sputtering, Si3N4 thin film

Thin films of AgxCu1 x 2ZnSn S,Se 4 x 0.05 0.20 prepared by spray pyrolysis

The recent investigation of kesterite type quaternary compounds showed that one of the main detrimental problems, which limits the efficiency of the solar cells based on these materials, is related to the high defect concentrations, mainly CuZn disorder. To overcome this problem partial replacement of Cu or Zn cations in the classical Cu2ZnSn S,Se 4 compounds was proposed. One of the promising cations was found to be Ag, which partially replaces Cu and the solid solution of AgxCu1 x 2ZnSn S,Se 4 ACZTSSe is formed. In the present study, ACZTSSe thin films with different Ag concentrations were deposited by the spray pyrolysis method, with subsequent annealing in S amp; 8239; amp; 8239;Se atmosphere. From the analysis of the chemical composition of the thin films a good correlation of measured silver concentration with initial concentration dissolved in the main solution for deposition for the samples with up to 15 Ag were found. These results were also confirmed by the structural studies and analysis of the Raman scattering spectra. On the other hand, thin film with higher Ag concentration 20 has shown strong compositional inhomogeneity and presence of secondary phases was detected. Analysis of the modulated surface photo voltage yielded the optical transition at 1.5 amp; 8239;eV, correlated with the band gap energy, and a transition at lower energy. From the temperature dependence of resistivity investigation no significant change in the resistivity for the samples with low silver concentration and strong increase for the samples with 20 of Ag were foun

Surface Photovoltage in Thin Films of Cu2ZnSn SxSe1 x 4 Obtained by Spray Pyrolysis

Spectral and time dependent surface photovoltage SPV measurements were performed on Cu2ZnSn SxSe1 x 4 CZTSSe thin films prepared on ITO glass substrates by spray pyrolysis at ambient atmosphere from aqueous solutions and subsequent selenization of Cu2ZnSnS4 CZTS layers. The morphology, stoichiometry and phases of the crystalline thin films were studied by electron microscopy, energy dispersive x ray analysis and xray diffraction, respectively. The CZTSSe thin films show mostly the kesterite type CZTSSe phases and are slightly copper deficient. The Se S Se ratio amounted to about 0.27. The onset energies of SPV signals were observed at about 1.0 and 1.5 eV. The transition at 1.0 eV can be attributed to the SnSe secondary phase with an indirect band gap of 0.90 eV. The energy of 1.5 eV corresponds to the band gap of the CZTSSe with about 25 of Se content. A slow relaxation process and a change of the sign set on at photon energies above 1.5 eV. Results are discussed in relation to the phase analysi