Tuning charge transport across junctions of ferrocene-containing polymer brushes on ITO by controlling the brush thickness and the tether lengths

Gan, Lu; Sangeeth, C. S. Suchand; Li, Yuan; Jańczewski, Dominik; Song, Jing; Nijhuis, Christian A.

doi:10.1016/j.eurpolymj.2017.10.009

Cited by 11 publications

(8 citation statements)

References 74 publications

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“…The “EGaIn technique” is a versatile method to form noninvasive contacts to, e.g., SAMs, polymer brushes, arrays of nanoparticles, monolayers of biomolecules, or dendrimers . EGaIn is coated with a thin conductive layer of GaO x (predominantly Ga 2 O 3 ) which gives this liquid‐metal non‐Newtonian properties.…”

Section: Introductionmentioning

confidence: 99%

Ultrasmooth and Photoresist‐Free Micropore‐Based EGaIn Molecular Junctions: Fabrication and How Roughness Determines Voltage Response

Karuppannan

Troadec

et al. 2019

Adv Funct Materials

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In molecular electronics, it is critical to minimize the sources that can result in defective electrodes, such as contaminations related to the fabrication process (photoresist and organic residues) or roughening of the electrode during etching, because these defects hamper the formation of well‐organized molecular structures. Junctions based on micropores are desirable as they are scalable, but micropores are not fabricated on ultrasmooth template‐stripped electrodes, and may suffer from stray capacitances and leakage currents across the insulating matrix. A method is reported to fabricate micropores in AlOx on template‐stripped Au based on a two‐step etch process so that the Au surface is not in direct contact with photoresistance during the fabrication process. These junctions do not suffer from stray capacitances or leakage currents, enable temperature variable measurements down to 8.5 K, have excellent current retention characteristics, and are stable for at least 2 months. By analyzing the normalized differential conductance curves and detailed comparison against junctions with cone‐shaped tips of EGaIn and EGaIn stabilized in a through‐hole in polydimethylsiloxane, how the surface roughness of top electrodes affects the effective contact area, influences the symmetry of the response of the junctions, and how the electrical characteristics scale with molecular length are established.

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Section: Introductionmentioning

confidence: 99%

Ultrasmooth and Photoresist‐Free Micropore‐Based EGaIn Molecular Junctions: Fabrication and How Roughness Determines Voltage Response

Karuppannan

Troadec

et al. 2019

Adv Funct Materials

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“…DMSO allows a high concentration of 50% w/w ratio of G5-PAMAM dendrimers and all grafted derivatives, which have a similar molality as the aqueous solutions prepared previously . Ferrocene (Fc) is selected as the internal additive due to its redox-stable property and its role in electron transduction, known to promote electron transfer , when cooperating with self-assemble monolayers, polymers, − polymer brushes, ,, dendrimers, − and proteins. , Dendrimers are the preferred polymer backbone, as they limit linear polymer entanglement with the intended design of low viscosity at high concentration of 10–50 wt %. G5-PAMAM dendrimers have primary amines group constrained to the surface, which facilitates grafting and intermolecular covalent cross-linking.…”

Section: Resultsmentioning

confidence: 99%

Voltage-Activated Adhesion through Donor–Acceptor Dendrimers

et al. 2018

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Previous investigations on voltage-activated adhesives were restricted to aqueous solvents, where current directed crosslinking competed with water electrolysis.Replacing aqueous would expand applications of electrocuring technology and avoid excessive foaming, but many organic solvents have high ohmic resistances that prevent electrical conduction. These impediments were overcome through internal grafting of ferrocene (Fc) and diazirine (Dz) donor-acceptor pairs on fifth generation polyamidoamine (G5-PAMAM) dendrimers, forming G5-Fc-Dz cografted conjugates, where Fc internal additives provided an instantaneous conductive hole (+) network towards the redox conversion of diazirine to carbene insertion adhesion in non-toxic organic solvents of DMSO, DMF, and PEG400. Size exclusion chromatography and 1 H, 19 F NMR evaluated the formulations before and after electrocuring to quantitate grafting ratios and crosslinked dendrimers. Cyclic voltammetry confirmed the retained redox behavior of grafted Fc and Dz.Real-time electro-rheology established the dependence of crosslinking kinetics and adhesion strength on applied voltage. Liquid G5-Fc 15 -Dz 30 conjugates reached gelation within 2 min and with a storage modulus up to 3.4 ± 0.5 kPa. For the first time, a model system demonstrates the design components necessary towards organic, voltage-activated one-pot adhesives. This has broad implications for adhesives, cosmetics, implantable biomaterials, and flexible biosensors.

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“…As af inding, the authors concluded that ferrocene brushesw ith longer side-chain length were softer while shorter alkyl linkersp roduced stiffer brushes and thusformed more packed layers.The same group synthesized andi nvestigated ferrocene-containing polymer brushes featuring different brush thicknesses (2-50 nm) grafted on ITO electrodes. [65] After contacting with eutectic gallium indium (EGaIn) electrodes on top, it was possible to study the efficiency of charget ransport-tunnelling versus hopping mechanism-across these dense layers as af unction of the brush thickness and side-chain length. This example again emphasizes the crucial role for the metallopolymer architecturef or charge transport leadingt od ifferent properties for the intended application,h ere, as electronic device.…”

Section: Grafting-from Strategies For Ferrocene-containing Monomersmentioning

confidence: 99%

Recent Trends in Metallopolymer Design: Redox‐Controlled Surfaces, Porous Membranes, and Switchable Optical Materials Using Ferrocene‐Containing Polymers

Gallei

Rüttiger

2018

Chemistry A European J

100

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Metallopolymers with metal functionalities are a unique class of functional materials. Their redox-mediated optoelectronic and catalytic switching capabilities, their outstanding structure formation and separation capabilities have been reported recently. Within this Minireview, the scope and limitations of intriguing ferrocene-containing systems will be discussed. In the first section recent advances in metallopolymer design will be given leading to a plethora of novel metallopolymer architectures. Discussed synthetic pathways comprise controlled and living polymerization protocols as well as surface immobilization strategies. In the following sections, we focus on recent advances and new applications for side-chain and main-chain ferrocene-containing polymers as (i) remote-switchable materials, (ii) smart surfaces, (iii) redox-responsive membranes, and some recent trends in (iv) photonic structures and (v) other optical applications.

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Tuning charge transport across junctions of ferrocene-containing polymer brushes on ITO by controlling the brush thickness and the tether lengths

Cited by 11 publications

References 74 publications

Ultrasmooth and Photoresist‐Free Micropore‐Based EGaIn Molecular Junctions: Fabrication and How Roughness Determines Voltage Response

Ultrasmooth and Photoresist‐Free Micropore‐Based EGaIn Molecular Junctions: Fabrication and How Roughness Determines Voltage Response

Voltage-Activated Adhesion through Donor–Acceptor Dendrimers

Recent Trends in Metallopolymer Design: Redox‐Controlled Surfaces, Porous Membranes, and Switchable Optical Materials Using Ferrocene‐Containing Polymers

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