p Si n SiC NANOLAYER PHOTOVOLTAIC CELL

Thin films of amorphous SiC were prepared by non reactive magnetron sputtering in an Ar atmosphere. A previously synthesized SiC 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 amp; 61655;cm. The Raman spectrum shows a dominant band at 982 cm 1, i.e. in the spectral region characteristic for SiC. The film thickness determined from atomic force microscopy measurements was about 8 40 nm, the height of the structural units of the film was 1 2 nm, while the linear dimensions were of the order of tens of nanometers. The amorphous nature of SiC grown on the Si substrate is confirmed by the presence of the diffraction rings which indicate the absence of the dominant orientation of the prepared films. A heterostructure consisting of a p type Si 100 and a layer of amorphous n type SiC was fabricated and studied. The investigation of its electrical and photoelectric properties shows that the entire space charge region is located in Si. This is in addition confirmed by the spectral dependence of the p Si n SiC photo sensitivity. The barrier height at the p Si n SiC interface estimated from dark I V characteristics is of the order of 0.9 1.0 eV. Load I V characteristics of p Si n SiC amorphous nanolayer solar cells demonstrate under standard AM1.5 illumination conditions a conversion efficiency of 7.2

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 2ZnSnS4 Based Thin Film Heterojunctions Influence of CdS Deposition Method

Cu2ZnSnSe4 CZTSe based solar cells, containing abundant elements, with Ag alloying have recently reached efficiency of 10.2 . The open circuit voltage in CZTSe devices is believed to be limited, in between other factors, by strong band tailing caused by an exceptionally high density of Cu Zn antisites. By replacing Cu in CZTSe with Ag, whose covalent radius is 15 larger than that of Cu and Zn, the density of I II antisite defects e.g., Cu Zn disorder is predicted to drop. In the present work, AgxCu1 x 2ZnSnS4 ACZTS heterostructures in three different architectures were investigated. The 5 and 10 silver substituted CZTS absorber layers were obtained by low cost spray pyrolysis technique, as well as three different methods for the CdS layer deposition were tested in order to optimize the ACZTS heterostructure efficienc

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

Improvement of CZTSSe film quality and superstrate solar cell performance through optimized post-deposition annealing

Improving the performance of kesterite solar cells requires high-quality, defect-free CZTS(Se) films with a reduced number of secondary phases and impurities. Post-annealing of the CZTS films at high temperatures in a sulfur or selenium atmosphere is commonly used to improve the quality of the absorbing material. However, annealing at high-temperatures can promote material decomposition, mainly due to the loss of volatile elements such as tin or sulfur. In this work, we investigate how the additional step of sulfurization at reduced temperatures affects the quality and performance of CZTSSe based solar cells. A comprehensive structural analysis using conventional and high resolution XRD as well as Raman spectroscopy revealed that the highest CZTSSe material quality with the lowest structural disorder and defect densities was obtained from the CZTS films pre-sulfurized at 420 °C. Furthermore, we demonstrate the possibility of using Sb 2 Se 3 as a buffer layer in the superstrate configuration of CZTSSe solar cells, which is possible alternative to replace commonly employed toxic CdS as a buffer layer. We show that the additional low-temperature selenization process and the successful use of Sb 2 Se 3 as a buffer layer could improve the performance of CZTSSe-based solar cells by up to 3.48%, with an average efficiency of 3.1%

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

Effects of annealing on elemental composition and quality of CZTSSe thin films obtained by spray pyrolysis

The spray pyrolysis was used for the deposition of Cu2ZnSn S, Se 4 CZTSSe kesterite thin films. The basic spray pyrolysis solution was prepared from two precursor solutions containing thiourea and cooled to a temperature near 1 C, which leads to minimizing the number of insoluble hydrates of copper chloride. The optimal substrate temperature was 350 C and the distance from the sprayer nozzle 30 cm. The as deposited Cu2ZnSnS4 layers were annealed in S2 atmosphere for the compensation of the sulfur deficiency and with the addition of Sn in order to avoid tin loss. Cu2ZnSn S, Se 4 thin films were obtained after the annealing of as deposited films in the S2 Se2 atmosphere. The surface morphology and composition of obtained thin films were investigated using the energy dispersive X ray EDX microanalysis and Raman spectroscopy measurements. The structural characterization by the grazing incidence X ray diffraction GIXRD showed the presence of Cu2 xS phases in all of the annealed thin films. For the Se S Se ratio of the thin films annealed in the S Se atmosphere was established from EDX measurements and analysis of GIXRD data, the results are in satisfactory agreemen