1,721,030 research outputs found
MOFs and COFs in Electronics: Bridging the Gap between Intrinsic Properties and Measured Performance
No full textAbstract Metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) hold promise for advanced electronics due to their tunable structural and electronic properties. However, discrepancies in reported electrical conductivities underscore the critical role of measurement methodologies. This review explores how intrinsic charge transport mechanisms (band‐like vs hopping) and extrinsic factors (grain boundaries, contact resistance) influence performance. This review critically examines the impact of common characterization methods – including two‐probe, four‐probe, van‐der‐Pauw, thin‐film, pellet, and single‐crystal techniques – on the assessment of electronic properties in MOFs and COFs. Case studies on copper benzenehexathiol (Cu 3 BHT) and copper hexahydroxytriphenylene (Cu 3 (HHTP) 2 ) illustrate how factors such as grain boundaries and contact resistance strongly affect measured conductivities. Advanced microscopic and spectroscopic techniques (conductive atomic force microscopy, terahertz spectroscopy) provide nanoscale or dynamic insights but may not reflect macroscopic device behavior. The necessity of standardized, method‐specific reporting and careful selection of characterization strategies to bridge the gap between intrinsic material properties and real‐world electronic performance are highlighted.Deutsche Forschungsgemeinschaft https://doi.org/10.13039/50110000165
Charge transport in single polymer fiber transistors in the sub-100 nm regime: temperature dependence and Coulomb blockade
No full textAbstractEven though charge transport in semiconducting polymers is of relevance for a number of potential applications in (opto-)electronic devices, the fundamental mechanism of how charges are transported through organic polymers that are typically characterized by a complex nanostructure is still open. One of the challenges which we address here, is how to gain controllable experimental access to charge transport at the sub-100 nm lengthscale. To this end charge transport in single poly(diketopyrrolopyrrole-terthiophene) fiber transistors, employing two different solid gate dielectrics, a hybrid Al2O3/self-assembled monolayer and hexagonal boron nitride, is investigated in the sub-50 nm regime using electron-beam contact patterning. The electrical characteristics exhibit near ideal behavior at room temperature which demonstrates the general feasibility of the nanoscale contacting approach, even though the channels are only a few nanometers in width. At low temperatures, we observe nonlinear behavior in the current–voltage characteristics in the form of Coulomb diamonds which can be explained by the formation of an array of multiple quantum dots at cryogenic temperatures.Japan Society for the Promotion of Sciencehttp://dx.doi.org/10.13039/501100001691Center for NanoScience, Ludwig-Maximilians-Universität Münchenhttp://dx.doi.org/10.13039/501100007153Solar Technologies go Hybridhttp://dx.doi.org/10.13039/100012027Deutsche Forschungsgemeinschafthttp://dx.doi.org/10.13039/50110000165
Ferroelectric and anomalous quantum Hall states in bare rhombohedral trilayer graphene
Full text linkNontrivial interacting phases can emerge in elementary materials. As a prime example, continuing advances in device quality have facilitated the observation of a variety of spontaneous quantum Hall-like states, a cascade of Stoner-like magnets, and an unconventional superconductor in bilayer graphene. Its natural extension, rhombohedral trilayer graphene is predicted to be even more susceptible to interactions given its even flatter low-energy bands and larger winding number. Theoretically, five spontaneous quantum Hall phases have been proposed to be candidate ground states. Here, we provide transport evidence for observing four of the five competing ordered states in interaction-maximized, dually-gated, rhombohedral trilayer graphene. In particular, at vanishing but finite magnetic fields, two states with Chern numbers 3 and 6 can be stabilized at elevated and low electric fields, respectively, and both exhibit clear magnetic hysteresis. We also reveal that the quantum Hall ferromagnets of the zeroth Landau level are ferroelectrics with spontaneous layer polarizations even at zero electric field, as evidenced by electric hysteresis. Our findings exemplify the possible birth of rich interacting electron physics in a simple elementary material
Density hysteresis and spin canting in rhombohedral trilayer graphene
No full textAbstract Spontaneous symmetry breaking leads to ordered phases, and hysteretic behavior often serves as a hallmark of emergent thermodynamic properties. Charge-neutral rhombohedral few-layer graphene is a strongly interacting system prone to layer antiferromagnetic (LAF) insulators, owing to its nearly flat bands with a high topological winding number. Here, in ultra-clean rhombohedral trilayer graphene devices—suspended to maximize interaction effects—we observe unexpected yet reproducible density hysteresis centered at the charge neutrality point (CNP), both at zero and finite electric fields. This hysteresis accentuates under an applied in-plane Zeeman field, but gradually weakens and eventually disappears as the temperature increases from 10 mK to 500 mK. These observations highlight the many-body nature of the LAF state, indicating a discontinuity in the chemical potential at the CNP and Zeeman field driven noncollinear spin canting. Our findings broaden the understanding of correlated phenomena in rhombohedral graphene and demonstrate both electric and magnetic control over antiferromagnetic order.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659National Science FoundationWelch Foundation http://dx.doi.org/10.13039/10000092
Nanoscopic Electrolyte-Gated Vertical Organic Transistors with Low Operation Voltage and Five Orders of Magnitude Switching Range for Neuromorphic Systems
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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