Elif Arici - Academia.edu (original) (raw)

Papers by Elif Arici

Hybrid composites based on inorganic nanomaterials embedded into a polymer matrix have were synth... more Hybrid composites based on inorganic nanomaterials embedded into a polymer matrix have were synthesized and characterized. Oxide semiconductor nanoparticles (SnO, SnO2, TiO2, Ga2O3, and NiO) and Si nanoparticles were employed as inorganic counterparts in the hybrid composite, while a conductive polymer (PEDOT:PSS) with diverse additives was used as the organic matrix. The composites were spin-coated on Si or glass substrates. The potential use of these materials in photovoltaic devices to improve Si surface passivation behavior was investigated. Besides, the use of the nanoparticles as active materials for anodes in Li-ion batteries was evaluated. Some other aspects, such as the durability and stability of these materials, were also assessed.

International Journal of Photoenergy, 2003

Hybrid materials consist of inorganic nanoparticles embedded in polymer matrices. An advantage of... more Hybrid materials consist of inorganic nanoparticles embedded in polymer matrices. An advantage of these materials is to combine the unique properties of one or more kinds of inorganic nanoparticles with the film forming properties of polymers. Most of the polymers can be processed from solution at room temperature enabling the manufacturing of large area, flexible and light weight devices. To exploit the full potential for the technological applications of the nanocrystalline materials, it is very important to endow them with good processing attributes. The surface of the inorganic cluster can be modified during the synthesis by organic surfactants. The surfactant can alter the dispersion characteristic of the particles by initiating attractive forces with the polymer chains, in which the particles should be homogenously arranged. In this review, we present wet chemical methods for the synthesis of nanoparticles, which have been used as photovoltaic materials in polymer blends. The ...

Journal of Materials Science: Materials in Electronics, 2011

... V. Senthamilselvi 4 K. Saravanakumar 4 R. Anandhi 4 B. Sakthivel 4 K. Ravichandran Post Gradu... more ... V. Senthamilselvi 4 K. Saravanakumar 4 R. Anandhi 4 B. Sakthivel 4 K. Ravichandran Post Graduate and Research Department of Physics, AVVM Sri Pushpam College (Autonomous), Poondi, Thanjavur, Tamil Nadu 613 503, India e-mail: kkr1365@yahoo.com ...

17th European …, 2001

First attempts were made to combine classical inorganic photovoltaic materials based on the chalc... more First attempts were made to combine classical inorganic photovoltaic materials based on the chalcogenides CuInSe2 and CuInS2 with the plasic solar cell polymers MDMO-PPV and P3HT to form bulk heterojunction solar cells. Whereas the synthesis of CuInSe2 did not ...

Advanced Functional Materials, 2003

Gastroenterology Report

Background Guidelines recommend that all patients with upper gastrointestinal bleeding (UGIB) und... more Background Guidelines recommend that all patients with upper gastrointestinal bleeding (UGIB) undergo endoscopy within 24 h. It is unclear whether a subgroup may benefit from an urgent intervention. We aimed to evaluate the influence of endoscopic hemostasis and urgent endoscopy on mortality in UGIB patients with high-risk stigmata (HRS). Methods Consecutive patients with suspected UGIB were enrolled in three Japanese hospitals with a policy to perform endoscopy within 24 h. The primary outcome was 30-day mortality. Endoscopic hemostasis and endoscopy timing (urgent, ≤6 h; early, >6 h) were evaluated in a regression model adjusting for age, systolic pressure, heart rate, hemoglobin, creatinine, and variceal bleeding in multivariate analysis. A propensity score of 1:1 matched sensitivity analysis was also performed. Results HRS were present in 886 of 1966 patients, and 35 of 886 (3.95%) patients perished. Median urgent-endoscopy time (n = 769) was 3.0 h (interquartile range [IQR],...

Organic Electronics, 2011

Low bandgap polymers are of great interest for the use in ́bulk heterojunction ́ solar cells to a... more Low bandgap polymers are of great interest for the use in ́bulk heterojunction ́ solar cells to achieve higher power conversion efficiencies by better matching the solar spectrum and therefore a better exploitation of lower photon energies. To be able to predict the general usability of these materials for this purpose the HOMO and LUMO levels of the polymers have to fit into the energetic properties of a solar cell. In this work the electrochemical determination of the HOMO and LUMO levels of different materials and a comparison of the optical and the electrochamical band gap is presented. The determination of the band edges and band gaps is done with cyclic voltammetry and electrochemical voltage spectroscopy of polymer films. The band gap obtained is compared with that from absorption spectroscopy. In situ spectroelectrochemistry for both UV-VIS and IR is performed to support the results from the electrochemical measurements.

Eine Vielzahl an wissenschaftlichen Erkenntnissen und technologischen Fortschritten bei der Herst... more Eine Vielzahl an wissenschaftlichen Erkenntnissen und technologischen Fortschritten bei der Herstellung und Charakterisierung organischer Feldeffekt-Transistoren (OFETs) während den letzten zwei Jahrzehnten hat es ermöglicht, dass erste Produkte mit organischer Elektronik am Markt sind. Gedruckte organische Elektronik umfasst Widerstände, Dioden und Transistoren und kann eine billige Alternative zu Silizium-basierten Systemen sein, im Speziellen bei großflächigen und flexiblen Anwendungen. Neben der Langzeitstabilität ist eine gute Reproduzierbarkeit der Strom-Spannungs (I-V) Kennlinien ein essentieller Parameter für die Verwendung dieser Bauteile. Diese I-V Kennlinien können eine Hysterese zeigen, was bei OFETs sehr häufig beim Messen einer Transfer Charakteristik [einer Variation der Gatespannung (V GS)] beobachtet wird. Es gibt vielfältige physikalische Gründe, die eine derartige Hysterese verursachen können, aber vergleichende wissenschaftliche Untersuchungen zu den unterschiedlichen Hysterese Phänomenen sind rar und ein umfassendes Bild der "Hysterese in OFETs" fehlt in der Literatur. Das erste Kapitel dieser Dissertation gibt einen ausführlichen Überblick zu verschiedensten physikalischen Effekten, die Hysterese verursachen können und exemplarische Beispiele aus der Literatur werden diskutiert. Detaillierte experimentelle Untersuchungen an OFETs, die Poly(vinyl alkohol) (PVA) als Dielektrikum verwenden, zeigen, wie die-aus der Literatur bekannte-Hysterese in diesen Bauteilen durch einen einstufigen Reinigungsschritt des PVAs minimiert werden kann. Temperaturabhängige Messungen, dielektrische Spektroskopie und Röntgen-Messungen vervollständigen das Bild der Hysterese in PVA basierten OFETs. Die unterschiedlichen Bauweisen hysterese-freier OFETs werden im letzten Kapitel untersucht und verglichen: top gate versus bottom gate und coplanar versus staggered. Im Rahmen dieser Untersuchungen wurden erstmals top gate OFETs, die PVA, das aus wässriger Lösung auf den organischen Halbleiter aufgetragen wird, verwenden, hergestellt und charakterisiert.

For increasing the power conversion efficiencies of polymer based solar cells, efficient harvesti... more For increasing the power conversion efficiencies of polymer based solar cells, efficient harvesting of the terrestrial solar spectrum is necessary. In this work, two approaches are presented. Firstly, low bandgap polymer, with bandgaps < 1.8 eV, are used for a better match of the solar spectrum. Secondly, the admixture of small molecule dyes into the photoactive polymer matrix increase the amount of absorbed light. Low bandgap polymers and their photophysical interaction with a fullerene type electron acceptor are characterised by a combined spectroscopic and device study. Sensitization of low bandgap solar cells with organic dyes and conjugated polymer is demonstrated. Possible sensitization mechanisms are discussed. Pristine low bandgap polymer solar cells as well as sensitized solar cells are characterised by I-V and photocurrent measurements. The device performance is analysed in terms of schematic energy level diagrams and diode response. Zusammenfassung Für höhere Effizienzen polymerbasierender Solarzellen wird ein effektives Einfangen des irdischen Sonnenlichtes benötigt. In dieser Arbeit werden zwei neue Zugänge präsentiert. Erstens, Polymere mit Bandlücken kleiner 1.8 eV führt zu einer besseren Überlappung mit dem Sonnenspektrum. Zweitens, die Zumischung organischer Farbstoffe erhöht die Lichtabsorption. Die Polymere und ihre Wechselwirkung mit fulleren-basierenden Elektronenakzeptoren wird sowohl spektroskopisch als auch in Solarzellen Anwendungen untersucht. Sensitivierungsmechanismen von Polymersolarzellen mit Polymeren und organischen Farbstoffen wird präsentiert. Sensitivierte wie auch nichtsensitivierte Solarzellen werden mittels I-V und Photostrommessungen charakterisiert. Die Leistungsparameter der Solarzellen werden anhand von Energiediagrammen und des Diodenverhaltens diskutiert. 6 CONCLUSION .

SPIE Proceedings, 2006

In this contribution, we present a new hybrid solar cell design. CuInS2 nanoparticles were synthe... more In this contribution, we present a new hybrid solar cell design. CuInS2 nanoparticles were synthesized using a low temperature colloidal route with organic surfactants to form an inorganic nanoporous hole transporting electrode. A soluble fullerene derivate PCBM (1-(3-methoxycarbonyl)-propyl-1-1-phenyl-(6,6) C61) was used for electron transport. We investigated the photovoltaic performance of the cells consisting of these CuInS2 and PCBM bilayers with and without a surface-adsorbed RuL2(NCS)/TBA(2:2) dye complex(where L= 2,2'-bipyridyl-4,4'-dicarboxylic acid; TBA= tetrabutylammonium). The cells containing the dye showed an improved photovoltaic response.

ACS Combinatorial Science, 2014

The release behavior of a model compound (β-naphthol orange) encapsulated in (meth)acrylate-based... more The release behavior of a model compound (β-naphthol orange) encapsulated in (meth)acrylate-based statistical copolymers under different environmental conditions was investigated. From monomers of varying polarity (methyl acrylate, ethyl acrylate, tert-butyl acrylate, 2-ethylhexyl methacrylate, and benzyl methacrylate) in combination with methacrylic acid, five polymer series were synthesized by free radical polymerization. The pH-dependent release kinetics were investigated via UV-vis spectroscopy at pH 1.2 and 6.8, simulating physiological conditions in the stomach and intestines. Furthermore, the influence of different ethanol contents (0 and 40 vol %) in the acidic medium was investigated. The whole approach was designed to meet the requirements of a high-throughput experimentation workflow.