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21.
The Role of Higher Lying Electronic States in Charge Photogeneration in Organic Solar Cells
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Giulia Grancini Maddalena Binda Stefanie Neutzner Luigino Criante Vittorio Sala Alberto Tagliaferri Guglielmo Lanzani 《Advanced functional materials》2015,25(44):6893-6899
The role of excess photon energy on charge generation efficiency in bulk heterojunction solar cells is still an open issue for the organic photovoltaic community. Here, the spectral dependence of the internal quantum efficiency (IQE) for a poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b]dithiophene)‐alt‐4,7‐(2,1,3‐benzothiadiazole)]:6,6‐phenyl‐C61‐butyric acid methyl ester (PCPDTBT:PC60BM)‐based solar cell is derived combining accurate optoelectronic characterization and comprehensive optical modeling. This joint approach is shown to be essential to get reliable values of the IQE. Photons with energy higher than the bandgap of the donor material can effectively contribute to enhance the IQE of the solar cell. This holds true independently of the device architecture, reflecting an intrinsic property of the active material. Moreover, the nanomorphology of the bulk heterojunction plays a crucial role in determining the IQE spectral dependence: the coarser and more crystalline, the lesser the gain in IQE upon high energy excitation. 相似文献
22.
Esposito Serena Setaro Antonio Maddalena Pasqualino Aronne Antonio Pernice Pasquale Laracca Marco 《Journal of Sol-Gel Science and Technology》2011,60(3):388-394
A modified sol–gel method was used to prepare cobalt doped silica thin film with a cobalt content of 10, 20 and 30 mol% (10Co, 20Co and 30Co). The prepared films were annealed at different temperatures in the range 400–1,000 °C, and their structural evolution examined.
The mixed valence cobalt oxide, Co3O4, crystallizes only in the sample with the higher cobalt content, while cobalt silicate is the only crystalline phase detected
in the sample 10Co and 20Co. Both the cobalt content and the temperature of heat treatment resulted to affect the nature of cobalt species dispersed
in the silica matrix. The 30Co was selected for further investigations by FTIR spectroscopy to follow the structural evolution of 30Co film as function of the temperature and UV–Vis to get information on the cobalt valence state. The optical gas-sensing properties
of 30Co films, containing Co3O4 as the major cobalt phase, were studied through the measuring of the film transmittance in dry air and in presence of dry
air containing variable concentrations of polluting gases, CO and NO2. The 30Co samples resulted to be highly sensitive to CO at room temperature. An explanation for the CO sensing characteristics, at
low temperature, was proposed by referring to the physisorption-related mechanics of CO. 相似文献
23.
Giovanni Petrillo Cinzia Tavani Lara Bianchi Alice Benzi Maria Maddalena Cavalluzzi Lara Salvagno Laura Quintieri Annalisa De Palma Leonardo Caputo Antonio Rosato Giovanni Lentini 《Molecules (Basel, Switzerland)》2021,26(13)
Twenty-two novel, variously substituted nitroazetidines were designed as both sulfonamide and urethane vinylogs possibly endowed with antimicrobial activity. The compounds under study were obtained following a general procedure recently developed, starting from 4-nitropentadienoates deriving from a common β-nitrothiophenic precursor. While being devoid of any activity against fungi and Gram-negative bacteria, most of the title compounds performed as potent antibacterial agents on Gram-positive bacteria (E. faecalis and three strains of S. aureus), with the most potent congener being the 1-(4-chlorobenzyl)-3-nitro-4-(p-tolyl)azetidine 22, which displayed potency close to that of norfloxacin, the reference antibiotic (minimum inhibitory concentration values 4 and 1–2 μg/mL, respectively). Since 22 combines a relatively efficient activity against Gram-positive bacteria and a cytotoxicity on eucharyotic cells only at 4-times higher concentrations (inhibiting concentration on 50% of the cultured eukaryotic cells: 36 ± 10 μM, MIC: 8.6 μM), it may be considered as a promising hit compound for the development of a new series of antibacterials selectively active on Gram-positive pathogens. The relatively concise synthetic route described herein, based on widely available starting materials, could feed further structure–activity relationship studies, thus allowing for the fine investigation and optimization of the toxico-pharmacological profile. 相似文献
24.
Giuseppe Cremonesi Piero Dalla Croce Alessandra Forni Maddalena Gallanti Raffaella Gandolfi Concetta La Rosa 《Tetrahedron: Asymmetry》2009,20(16):1940-1947
Enantiomerically pure (5R)-(?)-5-phenyl-4,5-dihydroisoxazole-3-carboxylic acid ethyl ester was obtained via enzymatic resolution of the corresponding racemic mixture using a lipase from hog pancreas (PPL). The following reduction of the ester group to the corresponding alcohol and the oxidation of the latter led to (5R)-(?)-5-phenyl-4,5-dihydroisoxazole-3-carbaldehyde, and the reaction between this and Schöllkopf’s reagent, (2R)-(+)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazine, gave mixtures of adducts with a good syn/anti ratio. The steric configurations of the major diastereoisomer were assigned on the basis of spectroscopic data and X-ray analysis. The subsequent controlled hydrolysis of the pyrazine ring led to β-(5-phenyl-4,5-dihydroisoxazol-3-yl)-serine methyl esters and the corresponding dipeptides with (R)-valine. Finally, reductive cleavage of the 4,5-dihydroisoxazole ring under hydrolytic conditions made it possible to obtain the corresponding polyfunctionalised dipeptides. 相似文献
25.
26.
G. Di Francia V. La Ferrara P. Maddalena D. Ninno L. P. Odierna V. Cataudella 《Il Nuovo Cimento D》1996,18(10):1187-1196
Summary In this paper we report on the frequency dependence of the AC conductivity of porous silicon in the range 10 Hz-100 kHz. Two
types of testing devices have been fabricated on three different series of samples formed electrochemically using as a starting
materialptype,n
−-type andn
+-type silicon substrates. For frequencies less than 20-40 kHz the conductivity is found to follow a sublinear frequency dependence.
This behaviour is typical of a carrier transport mechanism determined by an anomalous diffusion process. At higher frequencies
we find that surface states influence the transport mechanism. This suggests a double-channel transport mechanism: one related
to porous-silicon “volume” properties and the other more connected to the “surface” itself.
Paper presented at the III INSEL (Incontro Nazionale sul Silicio Emettiore di Luce) Torino, 12–13 October 1995. 相似文献
27.
Des Mazery R Pullez M López F Harutyunyan SR Minnaard AJ Feringa BL 《Journal of the American Chemical Society》2005,127(28):9966-9967
A highly enantioselective (up to 96% ee) conjugate addition of Grignard reagents, in particular, MeMgBr, to alpha,beta-unsaturated thioesters is provided as well as its application to a diastereo- and enantioselective iterative route to syn- and anti-1,3-dimethyl arrays and deoxypropionate subunits. The versatility of the method is illustrated in the synthesis of (-)-lardolure, a multimethyl-branched insect natural pheromone. 相似文献
28.
Luca Fumagalli Maddalena Binda Inma Suarez Lopez Dario Natali Marco Sampietro Sandro Ferrari Luca Lamagna Marco Fanciulli 《Organic Electronics》2009,10(4):692-695
A novel encapsulation structure to protect organic thin film transistors against oxygen and moisture contaminations is presented. The sealing architecture is comprised of three-layers: aluminum oxide deposited by means of Atomic Layer Deposition is the actual capping layer, while cross-linked poly-vinylphenol and poly-vinylphenol prevent the contamination/damage of the underlying organic semiconductor during the oxide growth. The process has negligible impact on device mobility but it enables poly-3-hexylthiophene based transistors to operate with an on/off ratio in excess of 103 even after 100 days of continuous ambient air exposure. 相似文献
29.
Maddalena Binda Tiziano Agostinelli Mario Caironi Dario Natali Marco Sampietro Luca Beverina Riccardo Ruffo Fabio Silvestri 《Organic Electronics》2009,10(7):1314-1319
In search for an organic material suitable for the detection of near-infrared electromagnetic radiation and at the same time capable of air stable operation of related devices, so to address the many applications envisaged with this technology (remote control, chemical/biological sensing, optical communication, spectroscopic and medical instruments), we explore the performance of a blend of hydrazone end-capped symmetric squaraines and phenyl C61 butyric acid methyl ester. We succeed in developing air stable solution-processed devices with external quantum efficiency in the NIR as high as 3.5% and response times of few hundreds of nanoseconds. Essential to these achievements has been a detailed characterization of the devices performed by correlating the optoelectronic performances to the morphology of the layers (extracted from AFM measurements) and to the charge carrier mobility (extracted from transistor structures), enabling their optimization at the chemical level, by tailoring the squaraine substitution pattern, and at the device level, by tuning the blend composition. We show that a good balance between holes and electrons mobility is essential for high EQE and fast response speed, and that a smooth morphology is mandatory to achieve long term air stability and operability with no need for encapsulation. 相似文献
30.
Serena Traboni Emiliano Bedini Maddalena Giordano Alfonso Iadonisi 《Tetrahedron letters》2019,60(27):1777-1780
A varied set of solvent-free, one-pot synthetic sequences were developed to carry out the orthogonal protection of saccharide polyols. These sequences are composed of an initial regioselective benzylation, silylation or iodination (under mildly basic conditions), followed by an acid catalyzed protection of two further hydroxyl sites via the generation of a cyclic acetal. These processes allow recycling of the ammonium or pyridinium side products generated in the former step as effective catalytic species for the latter step. 相似文献