@article{SchmeisserBurkovPaloumpaetal., author = {Schmeißer, Dieter and Burkov, Yevgen and Paloumpa, Ioanna and Mandal, Dipankar and Henkel, Karsten}, title = {Microscopic and Spectroscopic Characterization of Interfaces and Dielectric Layers for OFET Devices}, language = {en} } @misc{MuellerHenkelMandaletal., author = {M{\"u}ller, Klaus and Henkel, Karsten and Mandal, Dipankar and Seime, Bernd and Paloumpa, Ioanna and Schmeißer, Dieter}, title = {Spin coated organic ferroelectric films for non volatile memories}, language = {en} } @misc{MandalHenkelMuelleretal., author = {Mandal, Dipankar and Henkel, Karsten and M{\"u}ller, Klaus and Schmeißer, Dieter}, title = {Band gab determination of P(VDF-TrFE) copolymer film by electron energy loss spectroscopy}, language = {en} } @misc{SchmeisserTallaridaHenkeletal., author = {Schmeißer, Dieter and Tallarida, Massimo and Henkel, Karsten and M{\"u}ller, Klaus and Mandal, Dipankar and Chumakov, Dmytro and Zschech, Ehrenfried}, title = {Characterization of oxidic and organic materials with synchrotron radiation based XPS and XAS}, language = {en} } @incollection{MuellerBurkovMandaletal., author = {M{\"u}ller, Klaus and Burkov, Yevgen and Mandal, Dipankar and Henkel, Karsten and Paloumpa, Ioanna and Goryachko, Andriy and Schmeißer, Dieter}, title = {Microscopic and spectroscopic characterization of interfaces and dielectric layers for OFET devices}, series = {Organic Electronics : structural and Electronic Properties of OFETs}, booktitle = {Organic Electronics : structural and Electronic Properties of OFETs}, editor = {W{\"o}ll, Christof}, publisher = {Wiley-VCH}, address = {Weinheim}, isbn = {978-3-527-40810-8}, pages = {445 -- 468}, language = {en} } @misc{HenkelLazarevaMandaletal., author = {Henkel, Karsten and Lazareva, I. and Mandal, Dipankar and Paloumpa, Ioanna and M{\"u}ller, Klaus and Koval, Yuri and M{\"u}ller, P. and Schmeißer, Dieter}, title = {Electrical investigations on metal/ferroelectric/insulator/semiconductor structures using Poly[vinylidene fluoride trifluoroethylene] as ferroelectric layer for organic nonvolatile memory applications}, language = {en} } @article{MuellerMandalHenkeletal., author = {M{\"u}ller, Klaus and Mandal, Dipankar and Henkel, Karsten and Paloumpa, Ioanna and Schmeißer, Dieter}, title = {Ferroelectric properties of spin-coated ultrathin (down to 10nm) copolymer films}, language = {en} } @inproceedings{HenkelMandalSeimeetal., author = {Henkel, Karsten and Mandal, Dipankar and Seime, Bernd and Paloumpa, Ioanna and Lazareva, I. and M{\"u}ller, Klaus and Schmeißer, Dieter}, title = {Electrical investigations on MFIS structures consisting P[VDF/TrFE] as ferro-electric layer for non-volatile memory applications}, series = {Proceedings of 15th Workshop on Dielectrics in Microelectronics, Bad Saarow, 23 - 25 June 2008, Bad Saarow (Berlin)}, booktitle = {Proceedings of 15th Workshop on Dielectrics in Microelectronics, Bad Saarow, 23 - 25 June 2008, Bad Saarow (Berlin)}, pages = {159 -- 160}, language = {en} } @misc{MandalHenkelSchmeisser, author = {Mandal, Dipankar and Henkel, Karsten and Schmeißer, Dieter}, title = {Comment on "Preparation and Characterization of Silver-Poly(vinylidene fluoride) Nanocomposites:Formation of Piezoelectric Polymorph of Poly(vinylidene fluoride"}, language = {en} } @inproceedings{MandalHenkelSchmeisser, author = {Mandal, Dipankar and Henkel, Karsten and Schmeißer, Dieter}, title = {Control of the Crystalline Polymorph, Molecular Dipole and Chain Orientations in P(VDF-HFP) for High Electrical Energy Storage Application}, series = {International Conference on Nanoscience, Technology and Societal Implications (NSTSI), 2011}, booktitle = {International Conference on Nanoscience, Technology and Societal Implications (NSTSI), 2011}, publisher = {IEEE}, isbn = {978-1-4577-2035-2}, doi = {10.1109/NSTSI.2011.6111801}, language = {en} } @misc{MandalHenkelSchmeisser, author = {Mandal, Dipankar and Henkel, Karsten and Schmeißer, Dieter}, title = {The electroactive Beta-phase formation in Poly(vinylidene fluoride) by gold nanoparticles doping}, series = {Materials Letters}, journal = {Materials Letters}, number = {73}, issn = {0167-577X}, pages = {123 -- 125}, language = {en} } @misc{MandalMuellerHenkeletal., author = {Mandal, Dipankar and M{\"u}ller, Klaus and Henkel, Karsten and Schmeißer, Dieter}, title = {The effect of X-ray photoelectron spectroscopy measurement on P(VDF-TrFE) copolymer thin films}, series = {Applied Surface Science}, journal = {Applied Surface Science}, number = {261}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2012.07.144}, pages = {209 -- 213}, abstract = {The impact of prolonged X-ray irradiation during X-ray photoelectron spectroscopy (XPS) measurement was investigated on poly(vinylidene-trifluoroethylene) (P(VDF-TrFE)) thin films. It was observed that prolonged X-ray irradiation can accelerate the crosslinking of P(VDF-TrFE) and diminish the ferroelectric phase. Fourier transform infrared spectroscopy (FT-IR) data indicate that the ferroelectric phase diminishes completely after 360 kJ of X-ray irradiation dose and it induces the paraelectric phase. In this work, the main emphasis was given to the optimization of the X-ray irradiation dose during XPS measurements to maintain the ferroelectric phase within the copolymer films.}, language = {en} } @inproceedings{MandalHenkelDasetal., author = {Mandal, Dipankar and Henkel, Karsten and Das, Suken and Schmeißer, Dieter}, title = {Control of β- and γ-Phase formation in electroactive P(VDF-HFP) films by silver nano-particle doping}, series = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, booktitle = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, editor = {Heber, J{\"o}rg and Schlom, Darrell and Tokura, Yoshinori and Waser, Rainer and Wuttig, Matthias}, publisher = {Wiley-VCH}, address = {Weinheim}, isbn = {978-3-527-41191-7}, doi = {10.1002/9783527667703.ch69}, pages = {640 -- 641}, language = {en} } @misc{MandalHenkelSchmeisser, author = {Mandal, Dipankar and Henkel, Karsten and Schmeißer, Dieter}, title = {Improved performance of a polymer nanogenerator based on silver nanoparticles doped electrospun P(VDF-HFP) nanofibers}, series = {Physical Chemistry Chemical Physics}, volume = {2014}, journal = {Physical Chemistry Chemical Physics}, number = {16}, issn = {1463-9084}, doi = {10.1039/C3CP55238A}, pages = {10403 -- 10407}, abstract = {We report on the electrospinning of poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] nanofibers doped with silver nanoparticles for the preparation of a polymer based nanogenerator (PNG). It has been found that the yield of the piezoelectric phase is increased by the addition of silver nanoparticles. Furthermore, defects in the P(VDF-HFP) electrospun fibers are removed resulting in a significant enhancement in the output power of the PNG. A maximum generated PNG output voltage of 3 V with a current density of 0.9 μA cm-2 is achieved.}, language = {en} } @misc{GarainSinhaAdhikaryetal., author = {Garain, Samiran and Sinha, Tridib Kumar and Adhikary, Prakriti and Henkel, Karsten and Sen, Shrabanee and Ram, Shanker and Sinha, Chittaranjan and Schmeißer, Dieter and Mandal, Dipankar}, title = {Self-Poled Transparent and Flexible UV Light-Emitting Cerium Complex-PVDF Composite: A High-Performance Nanogenerator}, series = {ACS Applied Materials \& Interfaces}, volume = {2015}, journal = {ACS Applied Materials \& Interfaces}, number = {7}, issn = {1944-8244}, doi = {10.1021/am507522r}, pages = {1298 -- 1307}, abstract = {Cerium(III)-,N-dimethylformamide-bisulfate [Ce(DMF)(HSO4)3] complex is doped into poly(vinylidene fluoride) (PVDF) to induce a higher yield (99\%) of the electroactive phases (β- and γ-phases) of PVDF. A remarkable enhancement of the output voltage (∼32 V) of a nano-generator (NG) based on a nonelectrically poled cerium(III) complex containing PVDF composite film is achieved by simple repeated human finger imparting, whereas neat PVDF does not show this kind of behavior. This high electrical output resembles the generation of self-poled electroactiveβ-phase in PVDF due to the electrostatic interactions between the fluoride of PVDF and the surface-active positive charge cloud of the cerium complex via H-bonding and/or bipolar interaction among the opposite poles of cerium complex and PVDF, respectively. The capacitor charging capability of the flexible NG promises its applicability as piezoelectric-based energy harvester. The cerium(III) complex doped PVDF composite film exhibit an intense photoluminescence in the UV region, which might be due to a participation of electron cloud from negative pole of bipolarized PVDF. This fact may open a new area for prospective development of high-performance energy-saving flexible solid-state UV light emitters.}, language = {en} } @inproceedings{MandalMuellerSeifarthetal., author = {Mandal, Dipankar and M{\"u}ller, Klaus and Seifarth, Olaf and Hoffman, Patrick and Henkel, Karsten and Schmeißer, Dieter}, title = {Study of reactions at the interface P(VDF/TrFE)/Al and P(VDF/TrFE)/PEDOT:PSS}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 42}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 42}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 797}, abstract = {Due to potential use in non volatile memory application, Poly(vinylidene fluoride/trifluoroethylene) (P(VDF-TrFE)) is a great deal of interest, especially to produce organic field effect transistors (OFET). Right now it was found that Aluminum is one of the cost-effective inorganic electrode candidate. On the other hand, poly(3,4 ethylenedioxythiophene):poly(4-styrenesulfonate)(PEDOT:PSS) shows promising behavior for the application as organic electrode. In part of our investigations we have systematically studied surface interactions of organic ferroelectric thin films (P(VDF-TrFE))with inorganic (Al) and organic layers (PEDOT:PSS). By X-ray photoelectron spectroscopy (XPS) is has been found that there is a interfacial reaction with Al and the copolymer. In contrast, for electrodes, made of PEDOT: PSS, we found not such kind of behavior. In this case, we found no evidence for any surface reaction. Furthermore, we present our results concerning the orientation of permanent dipoles in the co-polymer (formed between hydrogen and fluorine atom). Here, we use Near-edge X-ray absorption fine structure (NEXAFS) analysis at the U 49/2 - PGM2 beam line of the BESSY-II Synchrotron. This work is supported by Deutsche Forschungsgemeinschaft (DFG) within priority program 1157 (DSCH 745/11-1).}, language = {en} } @inproceedings{MuellerMandalHenkeletal., author = {M{\"u}ller, Klaus and Mandal, Dipankar and Henkel, Karsten and Paloumpa, Ioanna and Schmeißer, Dieter}, title = {Interface reactions of ferroelectric copolymer layers with different electrode materials}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 830}, abstract = {The ferroelectric copolymer poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE)) is a possible material for low cost applications as organic nonvolatile memory element. We present an XPS interface investigation of the copolymer/electrode interface. Below 100nm film thickness, interface phenomena becomes important. Possible interface reactions could lead to a reduction of the ferroelectric functionality.We present a comparative study of the two interfaces Al/P(VDF-TrFE) and PEDOT:PSS/P(VDF-TrFE). The result is a clear indication of a surface reaction in between the Aluminum-electrodes. In contrast, for PEDOT:PSS the measurements shows a layer by layer formation of the interface PEDOT:PSS/PVDF without any reaction. Second, we present a study of remanent polarization of ultrathin spincoated films of the copolymer, in a thickness range from 5 to 100mn, with organic electrodes like PEDOT:PSS. The measurements are carried out by using the flatband shift of a capacitance-voltage (CV) characteristic. This shift of flatband voltage is used as value for the electric polarization of the polymer.}, language = {en} } @misc{TamangGhoshGarainetal., author = {Tamang, Abiral and Ghosh, Sujoy Kumar and Garain, Samiran and Alam, Md. Mehebub and Haeberle, J{\"o}rg and Henkel, Karsten and Schmeißer, Dieter and Mandal, Dipankar}, title = {DNA-Assisted β‑phase Nucleation and Alignment of Molecular Dipoles in PVDF Film: A Realization of Self-Poled Bioinspired Flexible Polymer Nanogenerator for Portable Electronic Devices}, series = {ACS Applied Materials \& Interfaces}, journal = {ACS Applied Materials \& Interfaces}, number = {7}, issn = {1944-8244}, doi = {10.1021/acsami.5b04161}, pages = {16143 -- 16147}, abstract = {A flexible nanogenerator (NG) is fabricated with a poly(vinylidene fluoride) (PVDF)film, where deoxyribonu-cleic acid (DNA) is the agent for the electroactive β-phase nucleation. Denatured DNA is co-operating to align the molecular-CH2/-CF2 dipoles of PVDF causing piezo- electricity without electrical poling. The NG is capable of harvesting energy from a variety of easily accessible mechanical stress such as human touch, machine vibration, football juggling, and walking. The NG exhibits high piezoelectric energy conversion efficiency facilitating the instant turn-on of several green or blue light-emitting diodes. The generated energy can be used to charge capacitors providing a wide scope for the design of self-powered portable devices.}, language = {en} } @inproceedings{MandalHenkelSchmeisser, author = {Mandal, Dipankar and Henkel, Karsten and Schmeißer, Dieter}, title = {A polymer nanogenerator based on silver nanoparticles doped electrospun P(VDF-HFP) nanofibers}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 208}, abstract = {The rising energy demand within the increasing mobility of human society has driven the development of new alternative power sources for portable devices with ultra-low electric power consumption. Based on its piezoelectric properties poly-vinylidene fluoride (PVDF) is a good candidate for mechanical energy harvesting for such devices. Moreover the copolymer poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] offers better film flexibility and cost-effectiveness than pure PVDF. We report on a polymer nanogenerator (PNG) based on electrospun P(VDF-HFP) nanofibers doped with silver nanoparticles (Ag-NPs). The electrospun fibers were characterized by FTIR, XPS, SEM and pressure imparting probe. It has been found that the yield of the piezoelectric phase is increased by the addition of Ag-NPs due to an interaction between surface charges of Ag-NPs and the molecular dipoles. Furthermore, defects in the P(VDF-HFP) electrospun fibers are removed. Accordingly, a significant enhancement in the output power of the PNG was found. Similar trends were also observed with Pd-NPs.}, language = {en} } @misc{GarainBarmanSinhaetal., author = {Garain, Samiran and Barman, Koushik and Sinha, Tridib Kumar and Jasimuddin, Sk and Haeberle, J{\"o}rg and Henkel, Karsten and Schmeißer, Dieter and Mandal, Dipankar}, title = {Cerium(III) Complex Modified Gold Electrode: An Efficient Electrocatalyst for the Oxygen Evolution Reaction}, series = {ACS Applied Materials and Interfaces}, volume = {8}, journal = {ACS Applied Materials and Interfaces}, number = {33}, issn = {1944-8244}, doi = {10.1021/acsami.6b05236}, pages = {21294 -- 21301}, abstract = {Exploring efficient and inexpensive electrocatalysts for the oxidation of water is of great importance for various electrochemical energy storage and conversion technologies. In the present study, a new water-soluble [Ce III(DMF) (HSO4)3] complex was synthesized and characterized by UV-vis, photoluminescence, and high-resolution X-ray photoelectron spectroscopy techniques. Owing to classic 5d →4f transitions, an intense photoluminescence in the UV region was observed from the water-soluble [CeIII(DMF (HSO4)3] complex. A stacking electrode was designed where self-assembled L-cysteine monolayer modified gold was immobilized with the synthesized cerium complex and was characterized by scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltam-metry. The resulting electrode, i.e., [CeIII(DMF)(HSO4)3]-L-cysteine-Au stacks shows high electrocatalytic water oxidation behavior at an overpotential of η ≈0.34 V under neutral pH conditions. We also demonstrated a way where the overpotential is possible to decrease upon irradiation of UV light.}, language = {en} }