1,721,484 research outputs found
Effect of lithium intercalation on the photovoltaic performances of photovoltachromic cells
No full textIn the last few years, a new class of smart multifunctional photoelectrochemical devices has been attracting the interest of several academic institutions and industrial companies: photovoltachromic cells, combining the features of photoelectrochromic cells with those of dye-sensitized solar cells. Here, we report the results of a detailed electrochemical analysis aiming at investigating the electrochemical behavior of these complex photoelectrochemical devices. In particular, we have been focused on the effect of Li+ ions displacement during the coloration of the electrochromic tungsten oxide on the performances of the photovoltaic unit. As we had previously observed striking differences between the performances of the barely photovoltaic mode (with the tungsten oxide in the bleached state) and the photovoltachromic mode (with the tungsten oxide in the colored state), we thus attempted to provide a reasonable physical interpretation to the observed phenomena. © 2013 John Wiley & Sons, Ltd
Multilayer hybrid LEDs based on colloidal inorganic semiconductors nanocrystal and PIN technology
No full textLight emitting devices (LEDs) based on colloidal semiconductor nanocrystals represent a matter of technological interest for the development of flat panel display and lighting systems. The appealing features of these materials are the high fluorescence efficiency, narrow ban edge emission, potential chemical stability, and tunable light emission across the visible spectrum. However the integration of these materials in the very promising PIN technology is still challenging due to the lack of an appropriate QD deposition technique. So far only wet deposition methods such as spin-coating and drop-casting have been exploited to realize QD thin film. Moreover QD thermal evaporation is not possible because of their high molecular weight. In this scenario we developed a dry, simple, and inexpensive deposition technique to transfer semiconductor QDs on organic semiconductor materials. We exploited this technique to fabricated an organic/inorganic hybrid red emitting device whit a doped hole transport layer
Nanotecnologie e nanodispositivi. Opportunità per involucri edilizi intelligenti ed efficienza energetica in edilizia
No full textEffect of lithium intercalation on the photovoltaic performances of photovoltachromic cells
No full textIn the last few years, a new class of smart multifunctional photoelectrochemical devices has been attracting the interest of several academic institutions and industrial companies: photovoltachromic cells, combining the features of photoelectrochromic cells with those of dye-sensitized solar cells. Here, we report the results of a detailed electrochemical analysis aiming at investigating the electrochemical behavior of these complex photoelectrochemical devices. In particular, we have been focused on the effect of Li+ ions displacement during the coloration of the electrochromic tungsten oxide on the performances of the photovoltaic unit. As we had previously observed striking differences between the performances of the barely photovoltaic mode (with the tungsten oxide in the bleached state) and the photovoltachromic mode (with the tungsten oxide in the colored state), we thus attempted to provide a reasonable physical interpretation to the observed phenomena
A new electrical model for the analysis of a partially shaded dye-sensitized solar cells module
No full textPartial shading is a commonly encountered mismatch problem in a photovoltaic system. In the drawing near perspective of their massive building integration, dye solar cell (DSC) modules may realistically receive different levels of irradiance, a situation similar to partial shading. In these conditions, the electrical characteristics of the DSC module significantly change. Here a general model for the description and the analysis of dye solar generators is proposed. A new equivalent circuit for DSCs has been developed that is characterized by the introduction of a second diode, capable to conveniently take into account the behavior of the reverse-biased cell/s. An experimental demonstration of the proposed two-diode model's validity is provided. A detailed description, based on numerical analysis, of the influence of partial shading on the photovoltaic performances of a DSC module made by four W-connected cells is given. We here demonstrate that the implementation of a two-diode model allows an excellent matching between the experimentally measured I-V characteristics of the partially shaded module and the simulated ones. Copyright (c) 2012 John Wiley & Sons, Ltd
The Bright Side of Perovskites
No full textIncubating in the rise of perovskite photovoltaic era, the advances in material design encourage further promising optoelectronic exploitations. Here, we evaluate halide perovskite envisioning light-emitting applications, with a particular focus to the role that this material can effectively play in the field, discussing advantages and limitations with respect to state of art competing players. Specific benefits derive from the use of low dimensional and nanostructured perovskites, marginally exploited in photovoltaic devices, allowing for a tuning of the excited states properties and for the obtainment of intrinsic resonating structures. Thanks to these unique properties, halide perovskite ensure a great potential for the development of high-power applications, such as lighting and lasing
Cells response sensing durotaxis by varying mechanical rigidity
No full textCell movement plays an
important role in many processes, such as immune
response and wound healing[1]. Physical
environment surrounding cells is a key factor in
response of cells to surfaces. Recent studies have
shown that cell movement is sensitive to the
rigidity of the substrate, a phenomenon defined as
“mechanotaxis or durotaxis”[2]. The purpose of
this study is to investigate cell migration by
fabricating uniform substrates imposing different
mechanical stiffness with patterns of various
shapes
Visual comfort assessment of smart photovoltachromic windows
No full textAn experimental study of photovoltachromic (PVCC) devices for dynamic solar control in buildings is presented. The fabricated devices underwent a complete opto-eletctrical characterization and the results obtained were employed as an input for the simulation of building integrated multifunctional windows. This multidisciplinary activity aims at achieving relevant feedbacks from the simulation of real large area devices in order to adjust and even direct further experimental efforts, before reaching the production phase. Devices having different electrochromic capacitances were used and the optical measurements became useful inputs for the simulation task. Simulation's results turned into feedbacks concerning the modulation of the transmittance spectra, the colour of bleached devices, the scale-up of PVCCs. Devices used in the current work showed a power peak of 4.22 mW/cm(2) at the maximum power point and a smart modulation of optical transmittance of 50.16% (at 700 nm). Simulations of natural light penetration in office buildings showed that the integration of PVCCs in traditional windows could dramatically increase indoor visual comfort. An increase of the average UDI for a typical room up to 71.8% and a decrease of intolerable glare levels (DGP higher than 0.45) down to 12% were the major benefits of the substitution of traditional clear glasses with integrated PVCCs. (C) 2013 Elsevier B.V. All rights reserved
A brief review of surface-functionalized cotton fabrics
No full textSurface modification of textiles with desired functionalities can be engineered by a considerable number of techniques ranging from traditional treatments to multifunctional approaches. Textiles, in fact, offer a challenging platform for functional modifications in order to meet additional strategic requirements for a large variety of applications. This article reviews recent developments involving modification of cotton textiles using physical methods (corona discharge, plasma) and chemical methods (vapor-phase atomic layer deposition treatment, surface grafting, enzymatic modification, cationic modification with nanoparticles, sol-gel technique, method and treatment with different reagents) and their characterization. The authors will present how the controlled wettability has been integrated into traditional materials to improve their performances and to extend their practical applications by developing new functionalities. The authors give a brief background on applications of cotton-modified surfaces and the development of novel innovative production techniques used to modify the surface materials and to improve the product quality
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