Effect of sensitization on the electrochemical properties of nanostructured NiO

Screen-printed NiO electrodes were sensitized with 11 different dyes and the respective electrochemical properties were analyzed in a three-electrode cell with the techniques of cyclic voltammetry and electrochemical impedance spectroscopy. The dye sensitizers of NiO were organic molecules of different types (e.g., squaraines, coumarins, and derivatives of triphenyl-amines and erythrosine B), which were previously employed as sensitizers of the same oxide in dye-sensitized solar cells of p-type (p-DSCs). Depending on the nature of the sensitizer, diverse types of interactions occurred between the immobilized sensitizer and the screen-printed NiO electrode at rest and under polarization. The impedance data recorded at open circuit potential were interpreted in terms of two different equivalent circuits, depending on the eventual presence of the dye sensitizer on the mesoporous electrode. The fitting parameter of the charge transfer resistance through the electrode/electrolyte interface varied in accordance to the differences of the passivation action exerted by the various dyes against the electrochemical oxidation of NiO. Moreover, it has been observed that the resistive term RCT associated with the process of dark electron transfer between the dye and NiO substrate is strictly correlated to the overall efficiency of the photoconversion () of the corresponding p-DSC, which employs the same dye-sensitized electrode as photocathode

Effect of sodium hydroxide pretreatment of NiOx cathodes on the performance of squaraine-sensitized p-type dye-sensitized solar cells

Squaraines are full-organic dyes employed as sensitizers in ptype dye-sensitized solar cells (p-DSSC). Their absorption spectrum shows a wide tunability that ranges from visible to NIR. Sensitization in the NIR region is crucial for exploiting a particularly intense portion of the solar spectrum. In this work three squaraines will be presented and tested as sensitizers in NiO-based p-type DSSC O4_C2, O4_C4 and O4_C12). The structures of the dyes differ for the length of the alkyl side chain (C2, C4 and C12). Alkyl side chains improve the solubility of the dye, influence the extent of dye loading on the electrode and affect the overall efficiency of devices. The generally low stability of squaraines represents a critical issue in view of their employment as sensitizers of p-DSSC. Such a problem becomes even more evident when this class of molecules is bound onto an acidic surface like the one of the photocathode here employed: non-stoichiometric nickel oxide (NiOx). NiOx possesses a quite acidic character because of the high surface concentration of Ni(III) sites. To buffer the surface acidity of NiOx due to the presence of high-valence states of nickel, we considered the electrode pretreatment with sodium hydroxide (NaOH) prior to sensitization. This assures a major stability of the solar cell. At the same time the chemisorbed hydroxyl moieties act as passivating agents of the Ni(III) sites thus diminishing the surface concentration of sites for dye anchoring. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

"Le je filmé, scritture del sé nell'audiovisivo: declinazioni e sviluppi teorici nel cinema franco-belga contemporaneo dal 1986 ad oggi

This research project is devoted to a French and Belgian autobiographical production hardly distributed outside France and Belgium except in single festivals or competitions. Films have been firstly selected according to a chronological criteria which dating back to 1986, when the first important international conference totally dedicated to autobiographical films took place in Brussell, extends till today. Through the reading of monographic issues devoted to first person films, press releases of thematic festivals consulted in archives and foreign libraries such as the Cinémathèque Française, Centre Pompidou e la Bibliothèque Nationale de France, a first selection of films has been carried out. After this research only those films in which the director is the main protagonist whether through the use of the voice over or through his/her presence in video. have been taken into account. Where these criteria were not applied, it was a declaration of the author to attest the autobiographical nature of the film. The aesthetic and formal analysis of the films selected, as well as the recurrence of thematic and expressive features, has allowed the creation of single chapters (Journal filmé, Autobiography/Selfportrait/Autofiction, Subjective documentary, Essay film). Each of them has been introduced by a survey of the main theoretical assumptions at the heart of each subject matter. This research aims at both providing an overview on English and French studies on subjective cinema and underling those innovative expressive, thematic and aesthetic choices the works analysed reveal. The first chapter explores the literary studies which starting from the second half of the nineteenth century have fostered a prolific survey on autobiographical works laying the foundations for audiovisual studies on subjective cinema. The second chapter gives an in-depth view on audiovisual media studies devoted to first person film narrations pointing out the core questions which inspire this specific production. The third chapter dedicated to those films labelled as video diaries has firstly analysed those literary studies dealing with diary writing in order to find out those features which have been actually recalled or modified in the films analysed. Different kinds of diary films have been sorted out. Through their diversity they overtly testify the hybrid nature of the subjective films we are dealing with. The fourth chapter has firstly pointed out those phases in the evolution of the documentary film which have deeply influenced the birth of strong subjective documentary productions. The films selected have been analysed adopting a theoretical approach based on Ethnic autobiography; it aims at finding out new possibilities for autobiographical films to be involved in a social, cultural and anthropological survey which could imply a dialogical relation between the subject and the world in which he lives in. The films included in the fifth chapter embody an experimental space in which documentary, fiction, essay and autobiography, filmed diary and fiction converge into the genre of autofiction, conceived as the post-modern version of autobiography. The sixth chapter, which deals with the essay form, tries to analyse how the most important philosophical and literary studies dedicated to a definition of the essay contributed to the development of the film essay structure

Emerging Photovoltaic Technologies and Eco-Design—Criticisms and Potential Improvements

An efficient waste management for emerging photovoltaic (PV) technologies is not mature yet. The problematic aspects along with the possible failure’s identification have a pivotal role in modelling the future end-of-life management strategies. The identification of substances of concern (e.g. high cost, low availability, and high toxicity) and valuable materials is a key point to better define the research priorities to improve the eco-design of these technologies. The ultimate goal is to promote the disposal processes which enhance the repair, refurbishment, and recover opportunities and so the profitability of recycling. These studies can also prompt the investigation of innovative materials which are more cost-effective and/or coming from renewable resources or secondary raw materials. Forecasting the waste management technologies for the emerging photovoltaics is highly challenging. In this context, our purpose is to provide an overview of the critical elements and understand the appropriate corrective improvements towards more sustainable technologies