P. Mangiapane

Stoichiometry effect on Cu2ZnSnS4 thin films morphological and optical properties

Thin films of Cu 2ZnSnS4 (CZTS) were prepared by sulfurization of multilayered precursors of ZnS, Cu, and Sn, changing the relative amounts to obtain CZTS layers with different compositions. X-Ray Diffraction (XRD), Energy Dispersive X-Ray spectroscopy, and SEM were used for structural, compositional, and morphological analyses, respectively. XRD quantitative phase analysis provides the amount of spurious phases and information on Sn-site occupancy. The optical properties were investigated by spectrophotometric measurements and Photothermal Deflection Spectroscopy. These films show a clear dependence of the optical and microstructural properties on the tin content. As the tin content increases we found: (i) an increase in both crystalline domain and grain size, (ii) an abrupt increase of the energy gap of about 150 meV, from 1.48 to 1.63 eV, and (iii) a decrease of sub-gap absorption up to two orders of magnitude. The results are interpreted assuming the formation of additional defects as the tin content is reduced.

Optoelectronic System-on-Glass for On-Chip Detection of Fluorescence

In this paper, we present an optoelectronic system-on-glass (SoG), suitable for detection of fluorescent molecule. It integrates, on the same glass substrate, an array of amorphous silicon (a-Si:H) photosensors and a thin film interferential filter. The system can be directly coupled with another glass substrate hosting a polydimethylsiloxane based microfluidic network where the fluorescent phenomena occur. The compatibility of the different technological steps to attain on the same glass substrate the photosensors and the filter determined the sequence, the selection of materials and the deposition parameters of the whole process. The electro-optical characterization of the photodiode, performed after the filter deposition, demonstrated the efficacy of the filter in reducing the excitation light. The system has been successfully tested using the ruthenium complex [Ru(phen)2(dppz)]2+, a fluorescent dye which works as DNA intercalating molecule.

Relevance Of TCO workfunction in n-silicon oxide emitter - c-Si (p) heterojunction solar cell

The amorphous /crystalline silicon heterojunction solar cells have largely demonstrated their usefulness to reach high efficiency. We have adopted a different and wider bandgap emitter based on silicon oxide, n-SiOx. A central role in this type of structure is played from the TCO workfunction whose value affects strongly the heterojunctions band structure at the emitter interface. RF magnetron sputtered TCO obtained with different deposition parameters, have been made in order to optimize their use in our heterojunction solar cell. Numerical simulation on the SiOx HJ, with TCO having proper workfunction value, show potential efficiency conversion well over the 23%. New Roman Bold font. An example is shown next.