Tobat P I Saragi

Publications of Tobat P I Saragi

• Ultralong single organic semiconducting nano/microwires based on spiro-substituted perylenetetracarboxylic diimide.

  Authors: Julia Lambrecht, Tobat P I Saragi, Kristian Onken, Josef Salbeck

  ACS applied materials & interfaces. 06/2011; 3(6):1809-12.

  An ultralong single organic semiconducting nano/microwire (NMW) is difficult to obtain. Here we show that this NMW can easily be prepared by using drying under solvent atmosphere method. ThisAn ultralong single organic semiconducting nano/microwire (NMW) is difficult to obtain. Here we show that this NMW can easily be prepared by using drying under solvent atmosphere method. This technique is not only unique, but also very compatible with our active material, spiro-substituted perylenetetracarboxylic diimide. A single NMW with a length of up to ∼5.5 mm and an aspect ratio of ∼9200 can be obtained. Finally, we succeeded to measure the electrical resistivity of a single NMW with values between 1 × 10(2) and 1 × 10(4) Ω m and the growth direction can be controlled as well by using a prestructured substrate.

• Bipolar redox behaviour, field-effect mobility and transistor switching of the low-molecular azo glass AZOPD.

  Authors: Michael Arlt, Ayna Scheffler, Irina Suske, Michael Eschner, Tobat P I Saragi, Josef Salbeck, Thomas Fuhrmann-Lieker

  Physical chemistry chemical physics : PCCP. 11/2010; 12(41):13828-34.

  We present electrochemical and spectroelectrochemical data for the bipolar azo compound N,N'-diphenyl-N,N'-bis[4-(phenylazo)phenyl]-4,4'diaminobiphenyl (AZOPD) demonstrating reversible bipolar redoxWe present electrochemical and spectroelectrochemical data for the bipolar azo compound N,N'-diphenyl-N,N'-bis[4-(phenylazo)phenyl]-4,4'diaminobiphenyl (AZOPD) demonstrating reversible bipolar redox behaviour with a bandgap of 2.1 eV. The reduced species formed upon two-electron transfer can be described as bis(radical anion) as was confirmed by comparison with a reference compound with only one azo chromophore. Hole and electron transport behaviour in amorphous films was demonstrated by the fabrication of organic field-effect transistors using gold and magnesium contacts, respectively. The transistors are sensitive to light due to E-Z photoisomerization.

• Interface morphologies and magnetization characteristics of Co70Fe30 thin films deposited on conjugated polymer thin films

  Authors: Tobat P.I. Saragi, Christoph Schmidt, Karin Schultz, Tanja Weis, Josef Salbeck, Arno Ehresmann

  Journal of Magnetism and Magnetic Materials. 01/2009; 321:2204.

• Solution-processed organic thin-film phototransistors based on donor/acceptor dyad

  Authors: Tobat P. I. Saragi, Michael Fetten, Josef Salbeck

  Applied Physics Letters. 07/2007;

  The authors report on solution-processed organic thin-film phototransistors based on donor/acceptor dyad. The drain current increases significantly and the switch-on voltage is shifted towardThe authors report on solution-processed organic thin-film phototransistors based on donor/acceptor dyad. The drain current increases significantly and the switch-on voltage is shifted toward positive bias as the incident light intensity is raised. Photoconductivity and the photovoltaic effect are assumed to be the underlying mechanism. Maximum responsivities of 0.3 and 0.03 A / W were obtained under irradiation at 370 nm at an incident light intensity of 1.4 μ W / cm ² and irradiation using a tungsten halogen lamp at an incident light intensity of 0.32 mW / cm ² , respectively.

• Spiro compounds for organic optoelectronics.

  Authors: Tobat P I Saragi, Till Spehr, Achim Siebert, Thomas Fuhrmann-Lieker, Josef Salbeck

  Chemical reviews. 05/2007; 107(4):1011-65.

• Ambipolar organic phototransistor

  Authors: Tobat P.I. Saragi, Kristian Onken, Irina Suske, Thomas Fuhrmann-Lieker, Josef Salbeck

  Optical Materials.

  We report on the fabrication and characterization of ambipolar organic phototransistors based on amorphous thin films of donor/acceptor dyadWe report on the fabrication and characterization of ambipolar organic phototransistors based on amorphous thin films of donor/acceptor dyad N-[7-(N,N-diphenylamino)-9,9′-spirobifluoren-2-yl]-N′-(2,5-di-tert-butylphenyl)-3,4:9,10-perylenetetracarboxylicdiimide. The mechanism of light enhanced photocurrent is based on photoinduced charge transfer between the donor and the acceptor unit. The photoresponsivity of up to 0.2 A/W can be obtained. The drain current is significantly increased by a factor of nearly 100 as the light is used as an additional control parameter, making the device interesting for sensor applications.