TY - JOUR A1 - Xia, Zhongfu A1 - Gerhard, Reimund A1 - Künstler, Wolfgang A1 - Wedel, Armin A1 - Danz, Rudi T1 - High surface-charge stability of porous polytetrafluoroethylene electret films at room and elvated temperatures Y1 - 1999 ER - TY - THES A1 - Wedel, Armin T1 - Untersuchungen zum Dipolschaltverhalten an Polymerfestkörpern Y1 - 1992 ER - TY - JOUR A1 - Kim, Yohan A1 - Heyne, Benjamin A1 - Abouserie, Ahed A1 - Pries, Christopher A1 - Ippen, Christian A1 - Günter, Christina A1 - Taubert, Andreas A1 - Wedel, Armin T1 - CuS nanoplates from ionic liquid precursors-Application in organic photovoltaic cells JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - Hexagonal p-type semiconductor CuS nanoplates were synthesized via a hot injection method from bis(trimethylsilyl) sulfide and the ionic liquid precursor bis(N-dodecylpyridinium) tetrachloridocuprate( II). The particles have a broad size distribution with diameters between 30 and 680 nm and well-developed crystal habits. The nanoplates were successfully incorporated into organic photovoltaic (OPV) cells as hole conduction materials. The power conversion efficiency of OPV cells fabricated with the nanoplates is 16% higher than that of a control device fabricated without the nanoplates. (C) 2018 Author(s). Y1 - 2018 U6 - https://doi.org/10.1063/1.4991622 SN - 0021-9606 SN - 1089-7690 VL - 148 IS - 19 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Kim, Jiyong A1 - Kim, Yohan A1 - Park, Kyoungwon A1 - Boeffel, Christine A1 - Choi, Hyung-Seok A1 - Taubert, Andreas A1 - Wedel, Armin T1 - Ligand Effect in 1-Octanethiol Passivation of InP/ZnSe/ZnS Quantum Dots-Evidence of Incomplete Surface Passivation during Synthesis JF - Small : nano micro N2 - The lack of anionic carboxylate ligands on the surface of InP/ZnSe/ZnS quantum dots (QDs), where zinc carboxylate ligands can be converted to carboxylic acid or carboxylate ligands via proton transfer by 1-octanethiol, is demonstrated. The as-synthesized QDs initially have an under-coordinated vacancy surface, which is passivated by solvent ligands such as ethanol and acetone. Upon exposure of 1-octanethiol to the QD surface, 1-octanethiol effectively induces the surface binding of anionic carboxylate ligands (derived from zinc carboxylate ligands) by proton transfer, which consequently exchanges ethanol and acetone ligands that bind on the incomplete QD surface. These systematic chemical analyses, such as thermogravimetric analysis-mass spectrometry and proton nuclear magnetic resonance spectroscopy, directly show the interplay of surface ligands, and it associates with QD light-emitting diodes (QD-LEDs). It is believed that this better understanding can lead to industrially feasible QD-LEDs. KW - colloidal quantum dots KW - incomplete surface passivation KW - indium KW - phosphide KW - surface chemistry KW - thiol passivation Y1 - 2022 U6 - https://doi.org/10.1002/smll.202203093 SN - 1613-6810 SN - 1613-6829 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Heyne, Benjamin A1 - Arlt, Kristin A1 - Geßner, André A1 - Richter, Alexander F. A1 - Döblinger, Markus A1 - Feldmann, Jochen A1 - Taubert, Andreas A1 - Wedel, Armin T1 - Mixed Mercaptocarboxylic Acid Shells Provide Stable Dispersions of InPZnS/ZnSe/ZnS Multishell Quantum Dots in Aqueous Media JF - Nanomaterials N2 - Highly luminescent indium phosphide zinc sulfide (InPZnS) quantum dots (QDs), with zinc selenide/zinc sulfide (ZnSe/ZnS) shells, were synthesized. The QDs were modified via a post-synthetic ligand exchange reaction with 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) in different MPA:MUA ratios, making this study the first investigation into the effects of mixed ligand shells on InPZnS QDs. Moreover, this article also describes an optimized method for the correlation of the QD size vs. optical absorption of the QDs. Upon ligand exchange, the QDs can be dispersed in water. Longer ligands (MUA) provide more stable dispersions than short-chain ligands. Thicker ZnSe/ZnS shells provide a better photoluminescence quantum yield (PLQY) and higher emission stability upon ligand exchange. Both the ligand exchange and the optical properties are highly reproducible between different QD batches. Before dialysis, QDs with a ZnS shell thickness of ~4.9 monolayers (ML), stabilized with a mixed MPA:MUA (mixing ratio of 1:10), showed the highest PLQY, at ~45%. After dialysis, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with a mixed MPA:MUA and a ratio of 1:10 and 1:100, showed the highest PLQYs, of ~41%. The dispersions were stable up to 44 days at ambient conditions and in the dark. After 44 days, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with only MUA, showed the highest PLQY, of ~34%. KW - quantum dots KW - cadmium-free KW - Cd-free KW - InP KW - InPZnS KW - multishell KW - mercaptocarboxylic acids KW - 3-mercaptopropionic acid KW - 11-mercaptoundecanoic acid KW - phase transfer KW - ligand exchange KW - aqueous dispersion KW - QDs Y1 - 2020 U6 - https://doi.org/10.3390/nano10091858 SN - 2079-4991 VL - 10 IS - 9 PB - MDPI CY - Basel ER - TY - GEN A1 - Heyne, Benjamin A1 - Arlt, Kristin A1 - Geßner, André A1 - Richter, Alexander F. A1 - Döblinger, Markus A1 - Feldmann, Jochen A1 - Taubert, Andreas A1 - Wedel, Armin T1 - Mixed Mercaptocarboxylic Acid Shells Provide Stable Dispersions of InPZnS/ZnSe/ZnS Multishell Quantum Dots in Aqueous Media T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Highly luminescent indium phosphide zinc sulfide (InPZnS) quantum dots (QDs), with zinc selenide/zinc sulfide (ZnSe/ZnS) shells, were synthesized. The QDs were modified via a post-synthetic ligand exchange reaction with 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) in different MPA:MUA ratios, making this study the first investigation into the effects of mixed ligand shells on InPZnS QDs. Moreover, this article also describes an optimized method for the correlation of the QD size vs. optical absorption of the QDs. Upon ligand exchange, the QDs can be dispersed in water. Longer ligands (MUA) provide more stable dispersions than short-chain ligands. Thicker ZnSe/ZnS shells provide a better photoluminescence quantum yield (PLQY) and higher emission stability upon ligand exchange. Both the ligand exchange and the optical properties are highly reproducible between different QD batches. Before dialysis, QDs with a ZnS shell thickness of ~4.9 monolayers (ML), stabilized with a mixed MPA:MUA (mixing ratio of 1:10), showed the highest PLQY, at ~45%. After dialysis, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with a mixed MPA:MUA and a ratio of 1:10 and 1:100, showed the highest PLQYs, of ~41%. The dispersions were stable up to 44 days at ambient conditions and in the dark. After 44 days, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with only MUA, showed the highest PLQY, of ~34%. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1026 KW - quantum dots KW - cadmium-free KW - Cd-free KW - InP KW - InPZnS KW - multishell KW - mercaptocarboxylic acids KW - 3-mercaptopropionic acid KW - 11-mercaptoundecanoic acid KW - phase transfer KW - ligand exchange KW - aqueous dispersion KW - QDs Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-486032 SN - 1866-8372 IS - 1026 ER - TY - JOUR A1 - Gerhard, Reimund A1 - Künstler, Wolfgang A1 - Görne, Thomas A1 - Pucher, Andreas A1 - Weinhold, Till A1 - Seiß, Martin A1 - Xia, Zhongfu A1 - Wedel, Armin A1 - Danz, Rudi T1 - Porous polytetrafluoroethylene space-charge electrets for piezoelectrical applications Y1 - 2000 ER - TY - JOUR A1 - Balischewski, Christian A1 - Choi, Hyung-Seok A1 - Behrens, Karsten A1 - Beqiraj, Alkit A1 - Körzdörfer, Thomas A1 - Gessner, Andre A1 - Wedel, Armin A1 - Taubert, Andreas T1 - Metal sulfide nanoparticle synthesis with ionic liquids state of the art and future perspectives JF - ChemistryOpen N2 - Metal sulfides are among the most promising materials for a wide variety of technologically relevant applications ranging from energy to environment and beyond. Incidentally, ionic liquids (ILs) have been among the top research subjects for the same applications and also for inorganic materials synthesis. As a result, the exploitation of the peculiar properties of ILs for metal sulfide synthesis could provide attractive new avenues for the generation of new, highly specific metal sulfides for numerous applications. This article therefore describes current developments in metal sulfide nano-particle synthesis as exemplified by a number of highlight examples. Moreover, the article demonstrates how ILs have been used in metal sulfide synthesis and discusses the benefits of using ILs over more traditional approaches. Finally, the article demonstrates some technological challenges and how ILs could be used to further advance the production and specific property engineering of metal sulfide nanomaterials, again based on a number of selected examples. KW - Ionic liquids KW - ionic liquid crystals KW - ionic liquid precursors KW - metal KW - sulfides KW - catalysis KW - electrochemistry KW - energy materials KW - LED KW - solar KW - cells Y1 - 2021 U6 - https://doi.org/10.1002/open.202000357 SN - 2191-1363 VL - 10 IS - 2 SP - 272 EP - 295 PB - Wiley-VCH CY - Weinheim ER -