Browsing by Author "Yakuphanoglu, Fahrettin"

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Fabrication of Hybrid Photodiode Systems: Bodipy Decorated Cyclotriphosphazene Covalently Grafted Graphene Oxides
(Royal Society Chemistry, 2020) Ozcan, Emrah; Aksoy, Burcu Topaloglu; Ecik, Esra Tanriverdi; Dere, Aysegul; Karabulut, Abdulkerim; Yakuphanoglu, Fahrettin; Cosut, Bunyemin
Combination of graphene sheets with various organic/inorganic functional groups could enhance the applications of graphene-based hybrid materials. Among them, BODIPY dyes are critically important due to their unique photonic properties and cyclophosphazenes are an excellent scaffold to anchor two or more chromophores. Thus, many attractive photonic characteristics can be shown in graphene/cyclophosphazene-BODIPY hybrid systems. Herein, the construction, synthesis and development of graphene-based hybrids (GO-CP-BODIPY) for enhanced photosensor applications were shown. Moreover, the photo-electrochemical properties of the novel hybrids were studied in particular using a photoconductivity measurement system. The produced photodiodes were quite sensitive to exposure light and exhibited photoconducting behavior under illumination light. The values of ideality factor and barrier height, which are two of the basic electrical parameters of a photodiode, were determined with the help of current-voltage characteristics for different light intensities. In addition to the dark current, it was found that a photocurrent was formed by the effect of illumination. Furthermore, the capacitanceversustime measurements performed at different light intensities showed that the device exhibited photocapacitive behavior. It is considered that the produced device in this study could be used in organic-based optoelectronic applications, especially as a photodiode or photosensor.
Zn-Doped Cdo Effects on the Optical, Electrical and Photoresponse Properties of Heterojunctions-Based Photodiodes
(Elsevier Science SA, 2021) Gozeh, Bestoon Anwer; Karabulut, Abdulkerim; Ismael, Cheman Baker; Saleh, Sarwar Ibrahim; Yakuphanoglu, Fahrettin
ZnO nanostructures have attracted great attention from researchers due to their interesting properties that include better crystallinity, high surface-area, improved electrical and optical properties. Furthermore, among the Transparent Conductive Oxide (TCO) family, CdO is one of the most attractive materials, as it can be used in a wide range of applications. Those intriguing properties make them highly desirable for various applications including photodiode. In this study, Al/Zn-CdO/p-Si/Al photodiodes were created with the CdO interfacial layer having pure and different contents of Zn (0, 0.1, 0.5, 2 and 4 at%) using the sol-gel spin coating method. All films were grown onto the p-type Si and glass to determine their electrical and optical properties. The effect of transparent Zn doped CdO photodiodes on their morphology, electrical and optical properties were investigated. The morphological characteristics and elemental compositions of prepared materials were examined by the SEM and EDX analyses. The obtained images indicated that the growth rate of the films was suppressed with the doping of Zn and presented a polycrystalline structure. The measurements of transmittance demonstrate that the coated films have well transparency value with the range of 80-85% in UV and visible zones. The optical bandgap of films evaluated by the linear fitting linearly increases with a dopant concentration of Zn and founded to be ranging from (1.9 - 2.37 eV). The currentvoltage characteristics of fabricated photodiodes demonstrated good rectifying behaviour when CdO doped with Zn0.1 The photoelectrical and photovoltaic behaviour with their parameters presented. Furthermore, the highest photosensitivity of 3.6 x 10(-4) was determined for Zn0.1. In the light of the obtained data, it was concluded that the produced Zn doped-CdO based device can be utilized in the optoelectronic applications, especially for the sensor and photodiode technology. (C) 2021 Elsevier B.V. All rights reserved.