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    Effect of TiO 2 modification with amino-based self-assembled monolayer on inverted organic solar cell
    (Elsevier B.V., 2017) Tozlu, Cem; Mutlu, Adem; Can, Mustafa; Havare, Ali Kemal; Demic, S.; İçli, S.
    The effects of surface modification of titanium dioxide (TiO 2 ) on the performance of inverted type organic solar cells (i-OSCs) was investigated in this study. A series of benzoic acid derivatized self-assembled monolayer (SAM) molecules of 4?-[(hexyloxy)phenyl]amino-3,5-biphenyl dicarboxylic acid (CT17) and 4?-[1-naphthyl (phenyl)amino]biphenyl-4-carboxylic acid (CT19) were utilized to modify the interface between TiO 2 buffer layer and poly-3 hexylthiophene (P3HT):[6,6]-phenyl C 61 butyric acid methyl ester (PC 61 BM) active layer having the device structure of ITO/TiO 2 /SAM/P3HT:PC 61 BM/MoO 3 /Ag. The work function and surface wetting properties of TiO 2 buffer layer served as electron transporting layer between ITO and PC 61 BM active layer were tuned by SAM method. The solar cell of the SAM modified devices exhibited better performance. The power conversion efficiency (PCE) of i-OSCs devices with bare TiO 2 electrodes enhanced from 2.00% to 2.21% and 2.43% with CT17 and CT19 treated TiO 2 electrodes, respectively. The open circuit voltage (V oc ) of the SAM treated TiO 2 devices reached to 0.60 V and 0.61 V, respectively, while the V oc of untreated TiO 2 was 0.57 V. The water contact angle of i-OSCs with CT17 and CT19 SAMs was also higher than the value of the unmodified TiO 2 electrode. These results show that inserting a monolayer at the interface between organic and inorganic layers is an useful alternative method to improve the performance of i-OSCs. © 2017 Elsevier B.V.
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    Functionalized organic semiconductor molecules to enhance charge carrier injection in electroluminescent cell
    (Elsevier Science Bv, 2017) Yalçın, Eyyüp; Kara, Duygu Akın; Karakaya, Caner; Yiğit, Mesude Zeliha; Havare, Ali Kemal; Can, Mustafa; Tozlu, Cem
    Organic semiconductor (OSC) materials as a charge carrier interface play an important role to improve the device performance of organic electroluminescent cells. In this study, 4,4"-bis(diphenyl amino)-1,1':3',1"-terphenyl-5'-carboxylic acid (TPA) and 4,4"-di-9H-carbazol-9-yl-1,1':3',1"-terphenyl-5'-carboxylic acid (CAR) has been designed and synthesized to modify indium tin oxide (ITO) layer as interface. Bare ITO and PEDOT:PSS coated on ITO was used as reference anode electrodes for comparison. Furthermore, PEDOT:PSS coated over CAR/ITO and TPA/ITO to observe stability of OSC molecules and to completely cover the ITO surface. Electrical, optical and surface characterizations were performed for each device. Almost all modified devices showed around 36% decrease at the turn on voltage with respect to bare ITO. The current density of bare ITO, ITO/CAR and ITO/TPA were measured as 288, 1525 and 1869 A/m(2), respectively. By increasing current density, luminance of modified devices showed much better performance with respect to unmodified devices. (C) 2017 Elsevier B.V. All rights reserved.
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    Structural properties of cadmium selenide nanowires prepared by chemical bath deposition for the electrical and photosensitive characteristics of the p-Si/CdSe heterojunction
    (Society of Photo-optical Instrumentation Engineers, 2020) Öksüzoğlu, Fatih; Gubur, Hülya Metin; Havare, Ali Kemal; Özmen, Sevda Ildan; Ünal, Muhittin; Tozlu, Cem
    Cadmium selenide (n-CdSe) thin films were grown on a silicon substrate with a polished surface and applied to the Schottky type device structure. The n-CdSe thin films produced depended on various deposition times at 70 degrees C by the use of the chemical bath deposition technique. XRD results show that the fabricated thin films consist of both cubic and hexagonal crystal systems. The morphology of CdSe was formed in nanograins and nanowire structures with respect to deposition times of 6 and 10 h, respectively. In addition to structural analysis of CdSe thin films, CdSe nanowires were used as an interfacial layer in a metal-semiconductor device to investigate its effects on the electrical and photosensitive characteristics of the device. As well as under forward bias current-voltage (I - V) conditions, the space charge limited current conduction behaviors were identified at low voltages. The results showed that the film produced at 10 h has a better performance compared to that produced at 6 h in terms of increased electric current.