102,055 research outputs found
Dye sensitised solar cells with nickel oxide photocathodes prepared via scalable microwave sintering
No full textPhotoactive NiO electrodes for cathodic dye-sensitised solar cells (p-DSCs) have been prepared with thicknesses ranging between 0.4 and 3.0 mm by spray-depositing pre-formed NiO nanoparticles on fluorine-doped tin oxide (FTO) coated glass substrates. The larger thicknesses were obtained in sequential sintering steps using a conventional furnace (CS) and a newly developed rapid discharge sintering (RDS) method. The latter procedure is employed for the first time for the preparation of p-DSCs. In particular, RDS represents a scalable procedure that is based on microwave-assisted plasma formation that allows the production in series of mesoporous NiO electrodes with large surface areas for p-type cell photocathodes. RDS possesses the unique feature of transmitting heat from the bulk of the system towards its outer interfaces with controlled confinement of the heating zone. The use of RDS results in a drastic reduction of processing times with respect to other deposition methods that involve heating/calcination steps with associated reduced costs in terms of energy. P1-dye sensitized NiO electrodes obtained via the RDS procedure have been tested in DSC devices and their performances have been analysed and compared with those of cathodic DSCs derived from CS-deposited samples. The largest conversion efficiencies (0.12%) and incident photon-to-current conversion efficiencies, IPCEs (50%), were obtained with sintered NiO electrodes having thicknesses of B1.5–2.0 mm. In all the
devices, the photogenerated holes in NiO live significantly longer (th B 1 s) than have previously been reported for P1-sensitized NiO photocathodes. In addition, P1-sensitised sintered electrodes give rise to relatively high photovoltages (up to 135 mV) when the triiodide–iodide redox couple is used.Science Foundation IrelandKnut and Alice Wallenberg FoundationSwedish Energy AgencyRoyal Society for ChemistryAM
Hydrogel electrolytes based on xanthan gum: Green route towards stable dye-sensitized solar cells
No full textThe investigation of innovative electrolytes based on nontoxic and nonflammable solvents is an up-to-date, intriguing challenge to push forward the environmental sustainability of dye-sensitized solar cells (DSSCs). Water is one of the best choices, thus 100% aqueous electrolytes are proposed in this work, which are gelled with xanthan gum. This well-known biosourced polymer matrix is able to form stable and easily processable hydrogel electrolytes based on the iodide/triiodide redox couple. An experimental strategy, also supported by the multivariate chemometric approach, is used here to study the main factors influencing DSSCs efficiency and stability, leading to an optimized system able to improve its efficiency by 20% even after a 1200 h aging test, and reaching an overall performance superior to 2.7%. In-depth photoelectrochemical investigation demonstrates that DSSCs performance based on hydrogel electrolytes depends on many factors (e.g., dipping conditions, redox mediator concentrations, etc.), that must be carefully quantified and correlated in order to optimize these hydrogels. Photovoltaic performances are also extremely reproducible and stable in an open cell filled in air atmosphere, noticeably without any vacuum treatments
Aqueous dye-sensitized solar cells: challenges in electrodes and electrolytes design
No full textDye sensitized solar cells (DSSCs) are not yet commercialized on large scale due to their issues concerning safety and long-term stability. In fact, standard high-efficiency DSSCs are prepared mainly with organic solvent-based liquid electrolytes, i.e. acetonitrile and methoxypropionitrile, and are often characterized by high vapor pressure, toxicity and flammability. In recent years, with the idea of creating efficient, safe, and low-cost DSSCs, the research moved the attention towards alternative solvent-based electrolytes. Above all, DSSCs with water-based electrolytes look like one of the best solution providing reduced costs, nonflammability, better stability, and environmental compatibility. Moreover, the possibility of gelling the liquid solvent into a polymeric matrix can reduce the electrolyte leakage outside the device, increasing the long-term stability. In this contribution, the investigation on a series of iodine/cobalt-based 100% aqueous electrolytes is presented. In parallel, photoanode preparation and sensitization is studied to achieve the best electrode/electrolyte interfaces. Finally, the gelation of aqueous electrolytes with bio-derived polymers is presented, leading to lab-scale devices stable for several months
Study on gelled aqueous electrolytes for DSSCs with different redox mediators
No full textDye sensitized solar cells (DSSCs) are a photovoltaic technology able to convert solar light into electricity and have recently achieved conversion efficiencies up to 14%. Nevertheless, DSSCs are not yet commercialized on large scale due to two particular aspects that have been poorly addressed, especially when it is considered that DSSC technology was conceived to be ecofriendly and inspired by photosynthesis. First, the standard electrolyte system is based on volatile organic solvents (e.g., acetonitrile, methoxypropionitrile), also flammable and toxic, which certainly affect the safety requirements when the device is installed. Secondly, the polymer electrolytes that have been introduced as solid or quasi-solid matrices to increase the stability of DSSCs are typically macromolecules derived from the petrochemical industry, which makes the DSSC technology not so much sustainable as it was in the initial intent. Above all, DSSCs with 100% water-based electrolytes appear as the best solution to reduce costs, increase safety, stability, and environmental compatibility, and have recently achieved efficiency up to 6%. Moreover, the idea of gelling the aqueous electrolyte into a low-cost bio-derived polymeric matrix open the possibility to increase long-term stability, preserving DSSCs sustainability. In this contribution, the study on fully aqueous electrolytes gelled with xanthan gum is presented. Thanks to our knowledge and to a multifactorial approach (Design of Experiment, DoE), the effects on DSSCs performances in function of type (I-/I3- vs Co-complex) and concentrations of the redox mediator are evaluate
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Effect of the preparation procedure on the morphology of thin TiO2 films and their device performance in small-molecule bilayer hybrid solar cells
No full textFlat titanium dioxide films, to be used as the acceptor layer in bilayer hybrid solar cell devices, were
prepared by spray-pyrolysis and by spin-casting. Both
preparation methods resulted in anatase titania films with
similar optical and electronic properties but considerably
different film morphologies. Spray pyrolysis resulted in dense
TiO2 films grown onto and affected by the surface roughness
of the underlying conducting glass substrates. The spin-casting
preparation procedure resulted in nanoporous titania films.
Hybrid solar cell devices with varying layer thickness of the
small-molecule semiconducting dye TDCV-TPA were investigated.
Devices built with spray-pyrolyzed titania substrates yielded conversion efficiencies up to 0.47%. Spin-cast titania
substrates exhibited short circuits for thin dye layer thickness. For thicker dye layers the performance of these devices was up to
0.6% due to the higher interfacial area for charge separation of these nanoporous TiO2 substrates
Investigation on bio-derived hydrogel electrolytes for dye-sensitized solar cells
No full textDye-sensitized solar cells (DSSCs) with water-based electrolytes are considered as one of the possible breakthrough towards DSSCs large-scale diffusion. If opportunely developed and optimized, aqueous solar cells can be considered a truly low impact photovoltaic device and no toxic components. Moreover, the possibility of gelling the electrolyte into a polymeric matrix can reduce the leakage outside the device, thus increasing the long-term stability. Above all, bio-derived polymers appear promising being renewable and easy available with low cost. In this contribution, the investigation on bio-derived hydrogel electrolytes for dye-sensitized solar cells is proposed. Moreover, the use of design of experiments (DoE) is demonstrated to be a useful chemometric technique for the concurrent investigation of a series of experimental factors that directly influence the photovoltaic performances of solar cells. Results obtained enlighten that a solid mathematical-statistical approach is fundamental to support the researchers and effectively drive the experiments towards the achievements of optimal operating conditions for aqueous solar cells
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3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
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