Laser Scribing of Thin Films Relevant for the Second Generation, Large Scale Monolithic Photovoltaic Solar Cells

Date du colloque : 09/2013International audienc

Low cost and high efficient, second generation thin film solar cells

Date du colloque : 09/2014International audienc

Sol Gel grown compound ZnO Thin Films for photovoltaic applications

Date du colloque : 09/2014International audienc

Progress on lead-free metal halide perovskites for photovoltaic applications: a review

ABSTRACT: Metal halide perovskites have revolutionized the field of solution-processable photovoltaics. Within just a few years, the power conversion efficiencies of perovskite-based solar cells have been improved significantly to over 20%, which makes them now already comparably efficient to silicon-based photovoltaics. This breakthrough in solution-based photovoltaics, however, has the drawback that these high efficiencies can only be obtained with lead-based perovskites and this will arguably be a substantial hurdle for various applications of perovskite-based photovoltaics and their acceptance in society, even though the amounts of lead in the solar cells are low. This fact opened up a new research field on lead-free metal halide perovskites, which is currently remarkably vivid. We took this as incentive to review this emerging research field and discuss possible alternative elements to replace lead in metal halide perovskites and the properties of the corresponding perovskite materials based on recent theoretical and experimental studies. Up to now, tin-based perovskites turned out to be most promising in terms of power conversion efficiency; however, also the toxicity of these tin-based perovskites is argued. In the focus of the research community are other elements as well including germanium, copper, antimony, or bismuth, and the corresponding perovskite compounds are already showing promising properties. GRAPHICAL ABSTRACT: [Image: see text

New π-electron donor (1,4-thioxane-2,3-diyldithio)ethylenedithiotetrathiafulvalene (ETOEDT-EDT-TTF) and its derivatives. Synthesis and characterization

We report more efficient way for the synthesis of 4,5-(1,4-oxathiane-2,3-diyldithio)-1,3-dithiole-2-thione and three new TTF-derived nonsymmetrical electron donors: the (1,4-thioxane-2,3-diyldithio)ethylenedithiotetrathiafulvalene (ETOEDT-EDT-TTF), (1,4-thioxane-2,3-diyldithio)propylenedithiotetrathiafulvalene (ETOEDT-PDT-TTF), and (1,4-thioxane-2,3-diyldithio)dimethylenedithiotetrathiafulvalene (ETOEDT-DMDT-TTF). For the first time we also present extended studies of the molecular structure, vibrational and electronic excitations of the donors. Based on theoretical and experimental Raman and infrared spectra as well as analysis of electron excitations of three new TTF-derived donors their spectral properties were described and discussed. © 2007 Elsevier Ltd. All rights reserved

Seasonal variations in dissolved organic matter composition using absorbance and fluorescence spectroscopy in the Dardanelles Straits – North Aegean Sea mixing zone

The Dardanelles Straits – North Aegean Sea mixing zone is the area where the less saline waters of Black Sea origin supply organic material to the oligotrophic Mediterranean Sea. The objective of this work was to assess the seasonal dynamics of dissolved organic matter (DOM) in this region based on the optical properties (absorbance and fluorescence). By combining excitation-emission fluorescence with parallel factor analysis (EEM-PARAFAC), four fluorescent components were identified corresponding to three humic – like components and one amino acid – like. The latter was dominant during all seasons. Chromophoric DOM (CDOM) and dissolved organic carbon (DOC) were found to be strongly coupled only in early spring when conservative conditions prevailed and the two water masses present (Black Sea Waters – BSW and Levantine Waters – LW) could be identified by their absorption coefficients (a300) and spectral slopes S275–295. In summer and autumn the relationships collapsed. During summer two features appear to dominate the dynamics of CDOM: i) photodegradation that acts as an important sink for both the absorbing DOM and the terrestrially derived fluorescent humic substances and ii) the release of marine humic like fluorescent substances from bacterial transformation of DOM. Autumn results revealed a source of fluorescent CDOM of high molecular weight, which was independent of water mass sources and related to particle and sedimentary processes. The removal of the amino acid-like fluorescence during autumn provided evidence that although DOC was found to accumulate under low inorganic nutrient conditions, dissolved organic nitrogenous compounds could serve as bacterial substrate. © 2016 Elsevier Lt