The precise localization and controlled chemical treatment of structures on a surface are significant challenges for common laboratory technologies. Herein, we introduce a microfluidic-based ...technology, employing a double-layer microfluidic device, which can trap and localize in situ and ex situ synthesized structures on microfluidic channel surfaces. Crucially, we show how such a device can be used to conduct controlled chemical reactions onto on-chip trapped structures and we demonstrate how the synthetic pathway of a crystalline molecular material and its positioning inside a microfluidic channel can be precisely modified with this technology. This approach provides new opportunities for the controlled assembly of structures on surface and for their subsequent treatment.
A series of new tetrathiafulvalene (TTF) derivatives bearing dimethoxycarbonyl and phenyl or phthalimidyl groups fused to the TTF core (6 and 15-18) has been synthesized as potential soluble ...semiconductor materials for organic field-effect transistors (OFETs). The electron-withdrawing substituents lower the energy of the HOMO and LUMO levels and increase the solubility and stability of the semiconducting material. Crystal structures of all new TTF derivatives are also described, and theoretical DFT calculations were carried out to study the potential of the crystals to be used in OFET. In the experimental study, the best performing device exhibited a hole mobility up to 7.5 × 10(-3) cm(2) V(-1) s(-1)).
The electronic donor α‐DT‐TTF (α‐dithiophene‐tetrathiafulvalene), which among the thiophenic TTF derivatives has remained essentially unexplored, and some of its charge transfer salts are described ...in detail in this paper. This donor was efficiently prepared by the homocoupling of 5,6‐thieno2,3‐d‐1,3‐dithiol‐2‐one, and its redox properties are intermediate between those of DT‐TTF (dithiophene‐tetrathiafulvalene) and BET‐TTF bis(ethylenethio)tetrathiafulvalene. The crystal structure of α‐DT‐TTF shows a molecular packing composed of trios of donor chains with alternating orientation. This pattern is clearly distinct from those previously found in all other thiophenic TTF donors. Used as an active material in a field‐effect transistor, α‐DT‐TTF presents a mobility μFE = 5 × 10–5 cm2/V s. The possibility to convert this new donor to conducting charge‐transfer salts with suitable anions was demonstrated by preparing its PF6– salts. Two salts with different crystal structures and stoichiometries were identified by X‐ray diffraction studies: (α‐DT‐TTF)(PF6)0.6 and (α‐DT‐TTF)2(PF6). The electrical conductivities of these salts, measured in the single crystal, range from 9 to 50 S/cm at room temperature. In all cases, the salts show a semiconducting behaviour and properties that are comparable to those of the analogous nonaromatic BET‐TTF salts.
α‐DT‐TTF (α‐dithiophene‐tetrathiafulvalene), a new thiophene TTF electronic donor is reported. Its synthesis and characterization opens the way to the preparation of a new series of charge‐transfer salts. The first member of this family is the salt with the PF6– anion, which shows a σr.t. value of 46 S/cm and properties comparable to those of the BET‐TTF bis(ethylenethio)tetrathiafulvalene analogue.
Bilayer films, composed of a thin‐layer of pyroresistive submicrometer‐sized crystals on top of a polymeric thin film, can be used both as a direct‐contact thermometer and as passive infrared sensor. ...These materials are capable of detecting, radiation of a wide‐range of wavelengths very rapidly and reversibly, as well as recognizing distant objects with applications in robotics, biomedicine, and human health care.
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•The high current density regime of single crystal and thin film OFETs is studied.•A pronounced non-hysteretic maximum in the transconductance is found.•Formation of local space charges close to ...the source electrode is demonstrated.•Space charge effects are device performance limiting effects in organic electronics.
The understanding of the charge carrier transport in electronic materials is of crucial interest for the design of efficient devices including especially the restraints that arise from device miniaturization. In this work the performance of organic thin-film and single crystal field-effect transistors with the same active material was studied in detail focusing on the high current density regime, where a pronounced non-hysteretic maximum in the transconductance was found. Interestingly, in this operation mode for both, thin films and single crystals, comparable densities of free and gate-induced charge carriers were estimated. Kelvin probe microscopy was used to measure the contact potential difference and the electrical field along the transistor channel during device operation exhibiting the formation of local space charges in the high current density regime.
The electronic donor alpha-DT-TTF (alpha-dithiophene-tetrathiafulvalene), which among the thiophenic TTF derivatives has remained essentially unexplored, and some of its charge transfer salts are ...described in detail in this paper. This donor was efficiently prepared by the homocoupling of 5,6-thieno2,3-d-1,3-dithiol-2-one, and its redox properties are intermediate between those of DT-TTF (dithiophene-tetrathiafulvalene) and BET-TTF bis(ethylenethio)tetrathiafulvalene. The crystal structure of alpha-DT-TTF shows a molecular packing composed of trios of donor chains with alternating orientation. This pattern is clearly distinct from those previously found in all other thiophenic TTF donors. Used as an active material in a field-effect transistor, alpha-DT-TTF presents a mobility µFE = 5×10-5 cm2/Vs. The possibility to convert this new donor to conducting charge-transfer salts with suitable anions was demonstrated by preparing its PF6- salts. Two salts with different crystal structures and stoichiometries were identified by X-ray diffraction studies: (alpha-DT-TTF)(PF6)0.6 and (alpha-DT-TTF)2(PF6). The electrical conductivities of these salts, measured in the single crystal, range from 9 to 50 S/cm at room temperature. In all cases, the salts show a semiconducting behaviour and properties that are comparable to those of the analogous nonaromatic BET-TTF salts. PUBLICATION ABSTRACT
This article is addressed to the development of flexible lightweight physical sensors suitable for body sensing technology. The polycarbonate films were covered with different organic molecular ...conductors to fabricate flexible strain sensing materials. The resulting surface-modified films were fully characterized by different microscopic and spectroscopic techniques. Their electric transport and electromechanical properties were studied as well. The investigations demonstrated that the electrical responses of these films suffice to measure very small pressure or temperature changes. A series of proof of concept prototypes of strain sensors were designed and a portable system including wireless data transmission was developed.
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