Thermoelectric Properties of Benzothieno-Benzothiophene Self-Assembled Monolayers in Molecular Junctions.

We report a combined experimental (C-AFM and SThM) and theoretical (DFT) study of the thermoelectric properties of molecular junctions made of self-assembled monolayers on Au of thiolated benzothieno-benzothiophene (BTBT) and alkylated BTBT derivatives (C8-BTBT-C8). We measure the thermal conductance per molecule at 15 and 8.8 pW/K, respectively, among the lowest values for molecular junctions so far reported (10-50 pW/K).

Molecular Junctions for Terahertz Switches and Detectors.

Molecular electronics targets tiny devices exploiting the electronic properties of the molecular orbitals, which can be tailored and controlled by the chemical structure and configuration of the molecules. Many functional devices have been experimentally demonstrated; however, these devices were operated in the low-frequency domain (mainly dc to MHz). This represents a serious limitation for electronic applications, although molecular devices working in the THz regime have been theoretically predicted.

Electronic properties of single Prussian Blue Analog nanocrystals determined by conductive-AFM.

We report a study of the electron transport (ET) properties at the nanoscale (conductive-AFM denoted as C-AFM hereafter) of individual Prussian Blue Analog (PBA) cubic nanocrystals (NCs) of CsCoFe, with a size between 15 and 50 nm deposited on HOPG. We demonstrate that these PBA NCs feature an almost size-independent electron injection barrier of 0.41 ± 0.

Field and Thermal Emission Limited Charge Injection in Au-C60-Graphene van der Waals Vertical Heterostructures for Organic Electronics.

Among the family of 2D materials, graphene is the ideal candidate as top or interlayer electrode for hybrid van der Waals heterostructures made of organic thin films and 2D materials due to its high conductivity and mobility and its inherent ability of forming neat interfaces without diffusing in the adjacent organic layer. Understanding the charge injection mechanism at graphene/organic semiconductor interfaces is therefore crucial to develop organic electronic devices. In particular, Gr/C60 interfaces are promising building blocks for future n-type vertical organic transistors exploiting graphene as tunneling base electrode in a two back-to-back Gr/C60 Schottky diode configuration.

Experimental observation of the role of countercations in modulating the electrical conductance of Preyssler-type polyoxometalate nanodevices.

Polyoxometalates are nanoscale molecular oxides with promising properties that are currently explored for molecule-based memory devices. In this work, we synthesize a series of Preyssler polyoxometalates (POMs), [Na⊂PWO], stabilized with four different counterions, H, K, NH, and tetrabutylammonium (TBA). We study the electron transport properties at the nanoscale (conductive atomic force microscopy, C-AFM) of molecular junctions formed by self-assembled monolayers (SAMs) of POMs electrostatically deposited on the ultraflat gold surface prefunctionalized with a positively charged SAM of amine-terminated alkylthiol chains.

Nanoscale electronic transport at graphene/pentacene van der Waals interfaces.

We report a study on the relationship between the structure and electron transport properties of nanoscale graphene/pentacene interfaces. We fabricated graphene/pentacene interfaces from 10 to 30 nm thick needle-like pentacene nanostructures down to two-three layer (2L-3L) dendritic pentacene islands, and we measured their electron transport properties by conductive atomic force microscopy (C-AFM). The energy barrier at the interfaces, , the energy position of the pentacene highest occupied molecular orbital (HOMO) with respect to the Fermi energy of graphene and the C-AFM metal tip was determined and discussed with an appropriate electron transport model (a double Schottky diode model and a Landauer-Buttiker model, respectively) taking into account the voltage-dependent charge doping of graphene.

The Effect of C60 and Pentacene Adsorbates on the Electrical Properties of CVD Graphene on SiO.

Graphene is an excellent 2D material for vertical organic transistors electrodes due to its weak electrostatic screening and field-tunable work function, in addition to its high conductivity, flexibility and optical transparency. Nevertheless, the interaction between graphene and other carbon-based materials, including small organic molecules, can affect the graphene electrical properties and therefore, the device performances. This work investigates the effects of thermally evaporated C60 (-type) and Pentacene (-type) thin films on the in-plane charge transport properties of large area CVD graphene under vacuum.

Correction: Redox-controlled conductance of polyoxometalate molecular junctions.

Correction for 'Redox-controlled conductance of polyoxometalate molecular junctions' by Cécile Huez , , 2022, , 13790-13800, https://doi.org/10.1039/D2NR03457C.

Charge Transport Across Au-P3HT-Graphene van der Waals Vertical Heterostructures.

Hybrid van der Waals heterostructures based on 2D materials and/or organic thin films are being evaluated as potential functional devices for a variety of applications. In this context, the graphene/organic semiconductor (Gr/OSC) heterostructure could represent the core element to build future vertical organic transistors based on two back-to-back Gr/OSC diodes sharing a common graphene sheet, which functions as the base electrode. However, the assessment of the Gr/OSC potential still requires a deeper understanding of the charge carrier transport across the interface as well as the development of wafer-scale fabrication methods.

Redox-controlled conductance of polyoxometalate molecular junctions.

We demonstrate the reversible photoreduction of molecular junctions of a phosphomolybdate [PMoO] monolayer self-assembled on flat gold electrodes, connected by the tip of a conductive atomic force microscope. The conductance of the one electron reduced [PMoO] molecular junction is increased by ∼10, and this open-shell state is stable in the junction in air at room temperature. The analysis of a large current-voltage dataset by unsupervised machine learning and clustering algorithms reveals that the electron transport in the pristine phosphomolybdate junctions leads to symmetric current-voltage curves, controlled by the lowest unoccupied molecular orbital (LUMO) at 0.

Thermal and electrical cross-plane conductivity at the nanoscale in poly(3,4-ethylenedioxythiophene):trifluoromethanesulfonate thin films.

Cross-plane electrical and thermal transport in thin films of a conducting polymer (poly(3,4-ethylenedioxythiophene), PEDOT) stabilized with trifluoromethanesulfonate (OTf) is investigated in this study. We explore their electrical properties by conductive atomic force microscopy (C-AFM), which reveals the presence of highly conductive nano-domains. Thermal conductivity in the cross-plane direction is measured by null-point scanning thermal microscopy (NP-SThM).

Terphenylthiazole-based self-assembled monolayers on cobalt with high conductance photo-switching ratio for spintronics.

Two new photo-switchable terphenylthiazole molecules are synthesized and self-assembled as monolayers on Au and on ferromagnetic Co electrodes. The electron transport properties probed by conductive atomic force microscopy in ultra-high vacuum reveal a larger conductance of the light-induced closed (c) form than for the open (o) form. We report an unprecedented conductance ratio of up to 380 between the closed and open forms on Co for the molecule with the anchoring group (thiol) on the side of the two N atoms of the thiazole unit.

Conductance switching of azobenzene-based self-assembled monolayers on cobalt probed by UHV conductive-AFM.

We report the formation of self-assembled monolayers of a molecular photoswitch (azobenzene-bithiophene derivative, AzBT) on cobalt via a thiol covalent bond. We study the electrical properties of the molecular junctions formed with the tip of a conductive atomic force microscope under ultra-high vacuum. The statistical analysis of the current-voltage curves shows two distinct states of the molecule conductance, suggesting the coexistence of both the trans and cis azobenzene isomers on the surface.

Thermal conductivity of benzothieno-benzothiophene derivatives at the nanoscale.

We study by scanning thermal microscopy the nanoscale thermal conductance of films (40-400 nm thick) of [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT-C8). We demonstrate that the out-of-plane thermal conductivity is significant along the interlayer direction, larger for BTBT (0.63 ± 0.

Long-range electron transport in Prussian blue analog nanocrystals.

We report electron transport measurements through nano-scale devices consisting of 1 to 3 Prussian blue analog (PBA) nanocrystals connected between two electrodes. We compare two types of cubic nanocrystals, CsCoIIIFeII (15 nm) and CsNiIICrIII (6 nm), deposited on highly oriented pyrolytic graphite and contacted by conducting-AFM. The measured currents show an exponential dependence with the length of the PBA nano-device (up to 45 nm), with low decay factors β, in the range 0.

Covalent Grafting of Polyoxometalate Hybrids onto Flat Silicon/Silicon Oxide: Insights from POMs Layers on Oxides.

Immobilization of polyoxometalates (POMs) onto oxides is relevant to many applications in the fields of catalysis, energy conversion/storage, or molecular electronics. Optimization and understanding the molecule/oxide interface is crucial to rationally improve the performance of the final molecular materials. We herein describe the synthesis and covalent grafting of POM hybrids with remote carboxylic acid functions onto flat Si/SiO substrates.

Molecular Electronics: From Single-Molecule to Large-Area Devices.

This Minireview focuses on conductance measurements on molecular junctions containing few tens of molecules, which are carried out by using two approaches: 1) conducting atomic force microscopy to study self-assembled monolayers on metal surfaces, and 2) tiny molecular junctions made of metal nanodots (diameter <10 nm), covered by fewer than 100 molecules and studied by conducting atomic force microscopy. In particular, this latter approach has new results to be obtained, or to previous results to be revisited which are reviewed here: 1) how the electron-transport properties of molecular junctions are modified by mechanical constraint, 2) the role of intermolecular interactions on the shape of conductance histograms of molecular junctions, and 3) the demonstration that a molecular diode can operate in the microwave regime up to 18 GHz.

Electrical detection of plasmon-induced isomerization in molecule-nanoparticle network devices.

We use a network of molecularly linked gold nanoparticles (NPSAN: nanoparticle self-assembled network) to demonstrate the electrical detection (conductance variation) of plasmon-induced isomerization (PII) of azobenzene derivatives (azobenzene bithiophene: AzBT). We show that PII is more efficient in a 3D-like NPSAN (cluster-NPSAN) than in a purely two-dimensional NPSAN (i.e.

Molecular signature of polyoxometalates in electron transport of silicon-based molecular junctions.

Polyoxometalates (POMs) are unconventional electro-active molecules with a great potential for applications in molecular memories, providing efficient processing steps onto electrodes are available. The synthesis of the organic-inorganic polyoxometalate hybrids [PM11O39{Sn(C6H4)C[triple bond, length as m-dash]C(C6H4)N2}]3- (M = Mo, W) endowed with a remote diazonium function is reported together with their covalent immobilization onto hydrogenated n-Si(100) substrates. Electron transport measurements through the resulting densely-packed monolayers contacted with a mercury drop as a top electrode confirms their homogeneity.

Probing Frontier Orbital Energies of {Co(PW)} Polyoxometalate Clusters at Molecule-Metal and Molecule-Water Interfaces.

Functionalization of polyoxotungstates with organoarsonate coligands enabling surface decoration was explored for the triangular cluster architectures of the composition [Co(HO)(OH)(p-RCHAsO)(α-PWO)] ({Co(PW)}, R = H or NH), isolated as Na[Co(OH)(HO)(CHAsO)(PWO)]·86HO (Na-1; triclinic, P1̅, a = 25.8088(3) Å, b = 25.8336(3) Å, c = 27.

Concentric-Electrode Organic Electrochemical Transistors: Case Study for Selective Hydrazine Sensing.

We report on hydrazine-sensing organic electrochemical transistors (OECTs) with a design consisting of concentric annular electrodes. The design engineering of these OECTs was motivated by the great potential of using OECT sensing arrays in fields such as bioelectronics. In this work, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based OECTs have been studied as aqueous sensors that are specifically sensitive to the lethal hydrazine molecule.

Interplay of multiple synaptic plasticity features in filamentary memristive devices for neuromorphic computing.

Bio-inspired computing represents today a major challenge at different levels ranging from material science for the design of innovative devices and circuits to computer science for the understanding of the key features required for processing of natural data. In this paper, we propose a detail analysis of resistive switching dynamics in electrochemical metallization cells for synaptic plasticity implementation. We show how filament stability associated to joule effect during switching can be used to emulate key synaptic features such as short term to long term plasticity transition and spike timing dependent plasticity.

Lay Crowd-Sourced Expertise (LCE) and Its Influence on the New Role of Patients: Ethical and Societal Issues.

The emergence of social media on the Internet allows patients to discuss about their chronic diseases within online communities sharing common interests. This allows patients to gather other patients' experience, and gain new knowledge that is usually not shared by healthcare professionals. In this context, further studies are required on the actual impact of the use of social networks on the quality of life of patients participating in these online communities, focusing on the evolving role and impact of Lay Crowdsourced expertise (LCE) in improving disease management and control.

A New Challenge to Research Ethics: Patients-Led Research (PLR) and the Role of Internet Based Social Networks.

A characteristic feature of the development of health-related social networks is the emergence of internet-based virtual communities, composed of patients. These communities go beyond the mere interchange of information concerning their conditions, intervening in the planning and execution of clinical research, including randomised controlled trials, in collaboration with health professionals. That was the case, in 2009, when patients suffering amyotrophic lateral sclerosis, a rare and severe disease, conducted a clinical trial in USA, organising themselves through an online platform.