1,722,315 research outputs found
Multilayer integrated structure for selective detection of Ochratoxin A
No full textThis work presents the design, fabrication and characterization of a system based on thin film technology for the selective detection of the natural fluorescence of Ochratoxin A. To this aim, the system optically couples an amorphous silicon photosensor with a long pass multi-dielectric filter, deposited on glass substrates. In particular, the filter rejects the wavelengths coming from the excitation source (centered at 340 nm) and transmits the emission spectrum (centered at 465 nm) of the mycotoxin, reducing therefore the background noise. The basic structure of the a-Si:H photosensors is a p-type/intrinsic/n-type stacked junction, deposited by Plasma Enhanced Chemical Vapor Deposition at temperatures ranging from 210 to 300 °C. Its responsivity at 465 nm is equal to 185 mA/W. The long pass filter is an interferential filter, constituted by alternating layers of TiO2 and SiO2. It has been designed by using a freeware software, and deposited by electron beam Physical Vapor Deposition at 250 °C. A very good agreement between modeled and experimental data of transmittance and reflectance has been achieved. In particular, transmittance of the filter varies by almost four orders of magnitude between 360 nm and 400 nm, showing its suitability in rejecting the excitation light. © 2015 IEEE
Integration of amorphous silicon photosensors with thin film interferential filter for biomolecule detection
No full textThis work presents a thin film device, combining, on the same glass substrate, photosensors and long-pass interferential filter to achieve a compact and efficient sensor for biomolecule detection. The photosensors are amorphous silicon stacked structures, while the interferential filter is fabricated alternating layers of silicon dioxide and titanium dioxide, directly grown over the photosensors. The system has been optimized to effectively detect the natural fluorescence of Ochratoxin A, a highly toxic mycotoxin present in different food commodities. In particular, the long-pass interferential filter has been designed to reject the wavelengths arising from the excitation source (centered at 330 nm) thus transmitting the OTA emission spectrum (centered at 470 nm). Experimental results show that the filter strongly reduces the photosensors quantum efficiency below 420 nm, while keeps it nearly constant at higher wavelength. © Springer International Publishing AG 2018
Highly miniaturized system for on-chip detection of DNA
No full textThis paper reports on the development of a lab-on-chip system for detection of DNA through the [Ru(phen)2(dppz)]2+ fluorescent intercalating dye. The device includes on the same glass substrate amorphous silicon photosensors, a thin film interferential filter and a microfluidic network based on polydimethylsiloxane. The suitability of the miniaturized system in detecting the fluorescence variation of the ruthenium complex, working as DNA intercalating molecules, is demonstrated
Inorganic photovoltaics - Planar and nanostructured devices
No full textSince its invention in the 1950s, semiconductor solar cell technology has evolved in great leaps and bounds. Solar power is now being considered as a serious leading contender for replacing fossil fuel based power generation. This article reviews the evolution and current state, and potential areas of near future research focus, of leading inorganic materials based solar cells, including bulk crystalline, amorphous thin-films, and nanomaterials based solar cells. Bulk crystalline silicon solar cells continue to dominate the solar power market, and continued efforts at device fabrication improvements, and device topology advancements are discussed. III-V compound semiconductor materials on c-Si for solar power generation are also reviewed. Developments in thin-film based solar cells are reviewed, with a focus on amorphous silicon, copper zinc tin sulfide, cadmium telluride, as well as nanostructured cadmium telluride. Recent developments in the use of nano-materials for solar power generation, including silicon and gallium arsenide nanowires, are also reviewed. © 2016 Elsevier Ltd. All rights reserved
Challenges for photovoltaic silicon materials
No full textThe August 2014 Special Issue of Solar Energy Materials & Solar Cells is dedicated to the 2nd workshop on Silicon Materials held in Rome, Italy, during October 7-8, 2013. During the workshop several discussions were held on the main question, 'Which are the challenges for Si material research'. The discussion focused on the results of the online survey and on the outstanding contributions of experts and presenting authors. One of the most debated points was how to select technologies that would enable cost reduction. A few possible scenarios to reduce costs were proposed. No consensus was reached with respect to the best scenario enabling the strongest cost reduction. During the workshop 27 contributions in addition to four personal statements from invited experts were given by industry, research institutes and universities
Optoelectronic System-on-Glass for On-Chip Detection of Fluorescence
No full textIn 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. © Springer International Publishing AG 2018
Localized metal plating on aluminum back side PV cells
No full textIn this work we demonstrate a new selective metallization technique to perform localized plating on the screen-printed Al contact using the innovative approach based on Dynamic Liquid Drop/Meniscus that is able to touch the cell back contact in specific defined positions and show that it is possible to produce suitable electrical and mechanical contact with Al-Si and thus to replace the silver from the back contact in the cell manufacturing process reducing the solar cell cost. A fast pre-treatment process was developed to clean and prepare the surface of the aluminum on the back side of PV cells allowing direct plating with good electrical contact. Several commercial aluminum screen printable pastes have been experimented also having different distribution of sphere particles dimensions. We have used high resolution Scanning Electron Microscopy (SEM) and compositional microanalysis with Energy Dispersive X-Ray microanalysis (EDX) to evaluate the metal dispersion within aluminum-silicon inter-diffused region and Transfer Length Method and current-voltage measurements to estimate the specific contact resistivity of the metal contact and series resistance of the overall solar cell device. We have found that the interconnection ribbon soldered on tin contacts plated on screen printed aluminum back contact shows adhesion higher (> 1N/mm) than that verified on screen printed silver over silicon. The main difference between a tin pad and a nickel-tin pad will be shown. Efficiency increase and fill factor are compared respect standard Al-Ag back contact PV cell
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