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

Dominant Cone-Rod Dystrophy: A Mouse Model Generated by Gene Targeting of the GCAP1/Guca1a Gene

Cone dystrophy 3 (COD3) is a severe dominantly inherited retinal degeneration caused by missense mutations in GUCA1A, the gene encoding Guanylate Cyclase Activating Protein 1 (GCAP1). The role of GCAP1 in controlling cyclic nucleotide levels in photoreceptors has largely been elucidated using knock-out mice, but the disease pathology in these mice cannot be extrapolated directly to COD3 as this involves altered, rather than loss of, GCAP1 function. Therefore, in order to evaluate the pathology of this dominant disorder, we have introduced a point mutation into the murine Guca1a gene that causes an E155G amino acid substitution; this is one of the disease-causing mutations found in COD3 patients. Disease progression in this novel mouse model of cone dystrophy was determined by a variety of techniques including electroretinography (ERG), retinal histology, immunohistochemistry and measurement of cGMP levels. It was established that although retinal development was normal up to 3 months of age, there was a subsequent progressive decline in retinal function, with a far greater alteration in cone than rod responses, associated with a corresponding loss of photoreceptors. In addition, we have demonstrated that accumulation of cyclic GMP precedes the observed retinal degeneration and is likely to contribute to the disease mechanism. Importantly, this knock-in mutant mouse has many features in common with the human disease, thereby making it an excellent model to further probe disease pathogenesis and investigate therapeutic interventions

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