Zschieschang U.,Max Planck Institute for Solid State Research |
Holzmann T.,Max Planck Institute for Solid State Research |
Holzmann T.,Ludwig Maximilians University of Munich |
Holzmann T.,Nanosystems Initiative Munich and Center for Nanoscience |
And 7 more authors.
Journal of Applied Physics | Year: 2015
We have synthesized crystals of two-dimensional layered tin disulfide (SnS2) by chemical vapor transport and fabricated field-effect transistors based on mechanically exfoliated SnS2 multilayer platelets. We demonstrate that the threshold voltage of these transistors can be modified by passivating the gate-oxide surface with a self-assembled monolayer of an alkylphosphonic acid, affording transistors with desirable enhancement-mode characteristics. In addition to a positive threshold voltage and a large on/off current ratio, these transistors also have a steep subthreshold swing of 4 V/decade. © 2015 AIP Publishing LLC.
Exner A.T.,TU Munich |
Pavlichenko I.,Max Planck Institute for Solid State Research |
Pavlichenko I.,Ludwig Maximilians University of Munich |
Baierl D.,TU Munich |
And 8 more authors.
Laser and Photonics Reviews | Year: 2014
An innovative integrated sensing platform for the detection of various chemical analytes via translating the photonic stop-band shift of a one-dimensional photonic crystal (PC) into an electrical current change is proposed. The miniaturized sensing platform features an organic light-emitting diode (OLED) as a light source and an organic photodetector (OPD) as a light sensor and allows for the detection of ethanol vapor concentrations down to ≈ 10 parts per million (ppm) in nitrogen, which corresponds to a stop-band shift of ≈ 27 pm. The resolution of the proposed platform exceeds the capabilities of most commercial spectrometers and by far the human eye, while, at the same time, such a sensor is less expensive and less power consuming than a spectrometer. The presented setup is generic and can detect optical changes in the transmission of PCs, which can be induced by both vapor adsorption or by a liquid analyte, as demonstrated with a microfluidic setup. An integrated sensing platform for the detection of various chemical analytes via translating the photonic stop-band shift of a one-dimensional photonic crystal into an electrical current change is proposed. The miniaturized sensing platform features an organic light-emitting diode as a light source and an organic photodetector as a light sensor and allows for the detection of ethanol vapor concentrations in nitrogen down to about 10 parts per million (ppm). © 2014 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Szendrei K.,Max Planck Institute for Solid State Research |
Szendrei K.,Ludwig Maximilians University of Munich |
Szendrei K.,Nanosystems Initiative Munich and Center for Nanoscience |
Ganter P.,Max Planck Institute for Solid State Research |
And 7 more authors.
Advanced Materials | Year: 2015
A new optical touchless positioning interface based on ultrasensitive humidity responsive 1D photonic crystals utilizing the giant moisture dependent swelling capacity of 2D phosphatoantimonate nanosheets is presented. The spatially confined, full spectral color change combined with reversible transparency switching induced by the humidity sheath of a human finger allows for real time, true color lateral finger motion tracking under touchless conditions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Ranft A.,Max Planck Institute for Solid State Research |
Ranft A.,Ludwig Maximilians University of Munich |
Ranft A.,Nanosystems Initiative Munich and Center for NanoScience |
Pavlichenko I.,Max Planck Institute for Solid State Research |
And 13 more authors.
Microporous and Mesoporous Materials | Year: 2015
Stimuli-responsive 1D photonic crystals, referred to as Bragg stacks, are capable of translating environmental changes into a color read-out through changes in the effective refractive index (RI) of the multilayer system upon infiltration with an analyte. The sensitivity and versatility of prototypic SiO2/TiO2 multilayers can be greatly enhanced by the use of nanoparticulate or mesoporous building blocks, or inherently microporous structures such as metal-organic frameworks (MOFs). Here, we introduce a stimuli-responsive ZIF-8 "defect" layer into SiO2/TiO2 multilayers in order to combine the high optical quality of a Bragg stack with the characteristic sorption properties of the MOF. The addition of a planar defect layer, either embedded in or deposited on top of the Bragg stack acts as a "dopant" and introduces a narrow band of allowed states in the photonic band gap, which can be utilized for the precise determination of the optical response of the Bragg stack. We demonstrate the impact of layer morphology, layer sequence and the position of the defect on the optical and vapor sorption properties of the photonic architectures. Moreover, a facile process is presented which allows for the clean inversion of the acid-sensitive ZIF-8 defect layer into a mesoporous layer in a one-step fashion, while the layer structure and optical quality of the stack architecture is preserved. © 2015 Elsevier Inc.
Weber D.,Max Planck Institute for Solid State Research |
Weber D.,Ludwig Maximilians University of Munich |
Schoop L.M.,Max Planck Institute for Solid State Research |
Duppel V.,Max Planck Institute for Solid State Research |
And 6 more authors.
Nano Letters | Year: 2016
Spin 1/2 honeycomb materials have gained substantial interest due to their exotic magnetism and possible application in quantum computing. However, in all current materials out-of-plane interactions are interfering with the in-plane order, hence a true 2D magnetic honeycomb system is still in demand. Here, we report the exfoliation of the magnetic semiconductor α-RuCl3 into the first halide monolayers and the magnetic characterization of the spin 1/2 honeycomb arrangement of turbostratically stacked RuCl3 monolayers. The exfoliation is based on a reductive lithiation/hydration approach, which gives rise to a loss of cooperative magnetism due to the disruption of the spin 1/2 state by electron injection into the layers. The restacked, macroscopic pellets of RuCl3 layers lack symmetry along the stacking direction. After an oxidative treatment, cooperative magnetism similar to the bulk is restored. The oxidized pellets of restacked single layers feature a magnetic transition at TN = 7 K if the field is aligned parallel to the ab-plane, while the magnetic properties differ from bulk α-RuCl3 if the field is aligned perpendicular to the ab-plane. The deliberate introduction of turbostratic disorder to manipulate the magnetic properties of RuCl3 is of interest for research in frustrated magnetism and complex magnetic order as predicted by the Kitaev-Heisenberg model. © 2016 American Chemical Society.
Vyas V.S.,Max Planck Institute for Solid State Research |
Lau V.W.-H.,Max Planck Institute for Solid State Research |
Lotsch B.V.,Max Planck Institute for Solid State Research |
Lotsch B.V.,Ludwig Maximilians University of Munich |
Lotsch B.V.,Nanosystems Initiative Munich and Center for NanoScience
Chemistry of Materials | Year: 2016
Solar fuel generation has attracted vast research interest as an environmentally benign means of producing energy from sunlight for catering to the ever growing world energy demands. As an alternative to inorganic semiconductors, organic polymers have entered the stage as promising photocatalytic systems offering a yet unprecedented scope for molecular engineering and precise tuning of optoelectronic properties. This perspective presents an overview of the development, state-of-the-art, and growth perspectives of this emerging field and highlights recent advances in photocatalyst design with a particular focus on structure-property-activity relationships in structurally well-defined 2D polymers for hydrogen evolution. © 2016 American Chemical Society.
Song W.,TU Munich |
Song W.,Nanosystems Initiative Munich and Center for NanoScience |
Martsinovich N.,University of Sheffield |
Heckl W.M.,TU Munich |
And 3 more authors.
Chemical Communications | Year: 2014
Monolayer self-assembly of a hexabrominated, three-fold symmetric aromatic molecule is studied at the heptanoic acid-graphite interface. Thermodynamical insights are obtained from an adapted Born-Haber cycle that is utilized to derive the overall enthalpy change including solvent effects. Comparison with theoretical entropy estimates suggests a minor influence of solvation. This journal is © the Partner Organisations 2014.