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Öğe Dark and illuminated electrical characteristics of Si-based photodiode interlayered with CuCo5S8 nanocrystals(Springer, 2020) Yildiz D.E.; Gullu H.H.; Sarilmaz A.; Ozel F.; Kocyigit A.; Yildirim M.Derived from the traditional dichalcogenide CuS structure, ternary transition metal chalcogenide nanoparticles in the form of CuCo5S8 are investigated under the aim of photodiode application. In addition to the detailed analysis on material characteristics of CuCo5S8 thin-film layer, the work is focused on the electrical characteristics of Au/CuCo5S8/Si diode to investigate its current–voltage, capacitance–voltage, and conductance–voltage characteristics under dark and illuminated conditions. CuCo5S8 nanocrystals with an average size of 5 nm are obtained using hot-injection method, and they are used to form thin-film interfacial layer between metal (Au) and semiconductor (Si). Under dark conditions, the diodes show about four orders in magnitude rectification rate and diode illumination results in efficient rectification with increase in intensity. The analysis of current–voltage curve results in non-ideal diode characteristics according to the thermionic emission model due to the existence of series resistances and interface states with interface layer. The measured current–voltage values are used to extract the main diode parameters under dark and illumination conditions. Under illumination, photogenerated carriers contribute to the current flow and linear photoconductivity behavior in photocurrent measurements with illumination shows the possible use of CuCo5S8 layer in Si-based photodiodes. This characteristic is also observed from the typical on/off illumination switching behavior for the photodiodes in transient photocurrent, photocapacitance, and photoconductance measurements with a quick response to the illumination. The deviations from ideality are also discussed by means of distribution of interface states and series resistance depending on the applied frequency and bias voltage. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.Öğe Digital fabrication of - Oxide electronics(2010) Marjanovlc N.; Hammerschmidt J.; Farnsworth S.; Rawson I.; Kus M.; Ozel F.; Tllkl S.The ink-jet printing technology is one of the most promising alternatives to photolithographic and masking technology allowing additive patterning of functional materials such as conductors, insulators, and semiconductors on a substrate. This approach enables the fabrication of cost-effective electronics. In particular, printable amorphous oxides have some advantages compared to other solution processable organic materials like atmospheric and temperature stability and relatively high field- effect mobility, which make them competitive candidates to be integrated in functional devices and smart systems. Here we report on the fabrication of basic electronic building blocks (e.g. a diode, resistor, capacitor) based on ink-jet printed amorphous oxides and metal contacts as active and passive device layers. Printed components are based on originally synthesized amorphous semiconductive oxides and metallic inks. After printing, low temperature sintering method developed by NovaCentrix® (PulseForge®) was performed in order to form the device active and passive layers. This was accomplished by using proprietary high-intensity flash lamps at very short pulse durations allowing us to use a low-cost Polyethylene terephthalate (PET) plastic film as the substrate material. Obtained results may open novel routes for the development of a next generation of Large Area Printed Electronics based on printed amorphous oxides.Öğe Facile preparation of amorphous NiWSex and CoWSex nanoparticles for the electrocatalytic hydrogen evolution reaction in alkaline condition(Elsevier B.V., 2020) Aslan E.; Sarilmaz A.; Yanalak G.; Chang C.S.; Cinar I.; Ozel F.; Patir I.H.The development of catalysts as an alternative to platinum group metals (PGMs) has great importance to improve the efficiency of hydrogen evolution reaction (HER). Herein, the novel amorphous ternary refractory metal selenides (MWSex; M = Co and Ni), which were synthesized by hot-injection approach, were firstly investigated on the electrocatalytic HER in alkaline media. Optical, electrochemical and magnetic properties of the electrocatalysts were explored, as well as the chemical structures and morphologies. These results clearly show that the obtained materials are having the amorphous crystal structure and are shaped as spherical and rod-like structures. Moreover, the addition of Ni and Co metals into the WSex structure were raised the catalytic activity of HER comparing to that of only WSex. This work paves the way for the exploration of copper-based amorphous selenides as electrocatalysts for the hydrogen evolution in order to replace noble metal Pt. © 2019 Elsevier B.V.Öğe Photocatalytic hydrogen evolution reaction activity comparable to 1-D nanofiber materials exhibited by the kesterite nanorods catalysts(Elsevier Ltd, 2020) Yanalak G.; Sarılmaz A.; Aslan E.; Ozel F.; Patir I.H.Copper-based earth-abundant chalcogenides (kesterite) such as Cu2CoSnS4 and Cu2NiSnS4 are important class due to their outstanding performance and earth-abundant composition. Here, we have successfully synthesized Cu2CoSnS4, Cu2NiSnS4 and Cu2ZnSnS4 nanorods by a hot-injection technique. The photocatalytic hydrogen production activities of rod-like Cu2XSnS4 (X = Co, Ni and Zn) catalysts have been investigated by using electron donor triethanolamine and photosensitizer eosin-Y under visible-light irradiation. The hydrogen evolution rates for the nanorods change in the order of Cu2NiSnS4> Cu2CoSnS4> Cu2ZnSnS4 (5117 ?molg?1h?1, 1342 ?molg?1h?1 and 719 ?molg?1h?1) respectively. The hydrogen evolution activities of Cu2XSnS4 nanorods have been compared to that of nanofiber and nanodot forms of Cu2XSnS4 catalysts. Cu2XSnS4 nanorods have been showed comparable photocatalytic activity for the hydrogen evolution compared with 1-D nanofiber Cu2XSnS4 catalysts. © 2020 Elsevier Ltd
