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A new asymmetric anthracene derivative with high mobility
摘要： An asymmetric anthracene derivative (4-HDPA) was designed and synthesized. With the optimization of proper scenario of fabrication process, top-contact thin film devices based on 4-HDPA exhibit mobility as high as 3.59 cm2 V–1 s–1, while its single-crystal devices exhibit mobility as high as 5.12 cm2 V–1 s–1, which is higher than the symmetrical counterpart of 4-HDPA in both single-crystal and thin film devices.
关键词： organic field-effect transistor (OFET),mobility,asymmetric,anthracene derivative
更新于2025-09-23 15:23:52
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Influence of Pendant Group on Mobility of Organic Thin Film Transistor in Correlation with Reorganization Energy of Molecules
摘要： Charge transport properties of common donor copolymers in organic photovoltaics, poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7) and poly([2,6′-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b]dithiophene]{3-fluoro-2[(2-ethylhexyl) carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7-Th), with molecular structures differing only in the pendant group, are studied. This is the first report of field-effect transistor mobility (μFET) of PTB7-Th (0.14 cm2 V?1 s?1) and the highest μFET for PTB7 (0.01 cm2 V?1 s?1). μFET of PTB7-Th is found to be almost one order of magnitude higher than PTB7. To understand the influence of molecular structure on charge transport, hole reorganization energy (λh) is calculated from first-principles. λh of PTB7-Th (≈150 meV) is found to be lower than PTB7 (≈346 meV). Further, the ratio of hopping rate versus square of charge transfer integral calculated from Marcus theory using λh for these systems is found to indicate a higher rate of hole transfer across dimers or homojunction interface for PTB7-Th. These results are supplemented by experimentally determined λ using bulk-heterojunction organic solar cells, where λPTB7-Th≈200 meV and λPTB7≈310 meV follow a similar trend. The effective hole-mobility estimation from BHJ devices correlates well with these λ values. This study provides understanding of charge transport properties via reorganization energy, as a function of pendant group without altering the backbone of the chains.
关键词： OFET,mobility,reorganization energy,pendant groups
更新于2025-09-23 15:23:52
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Asymmetric Pentacenes for Solution-Processed Organic Field-Effect Transistors
摘要： Background: Symmetrically substituted pentacenes have been traditionally used as semiconductors for solution-processed p-channel Organic Field Effect Transistors (OFETs). The aims of this paper are to introduce asymmetrically substituted pentacenes in the active layer and to examine the impact of the polyaromaticity of the pendant groups on the device characteristics. Methods: Research and online content related to asymmetrically substituted pentacenes is reviewed, the synthesis of the different pentacenes is described and the procedure used to introduce these semiconductors in devices is detailed. Comparison with a reference material is provided. Results: Extension of the polyaromaticity of the pendant group of pentacene greatly contributes to enhance the device performances. Impact of the pendant group on the morphology of the active layer is evidenced by the roughness decreasing with the increase of aromatic ring in the substituent. Conclusion: We demonstrate the extension of the π-conjugation of the aromatic end-group to drastically impact both ON/OFF ratio and charge carrier mobilities, mainly due to various degree of crystal formation characteristics in the film. Best results were obtained with the most extended one, namely the anthracene moiety which showed a mobility comparable to that of the benchmark TIPS-pentacene with OFETs that used hexamethyldisilazane as the gate dielectric passivation layer.
关键词： solution-process,semiconductor,organic materials,OFET,Mobility,TIPS-pentacene
更新于2025-09-23 15:23:52
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N-Type Semiconducting Behavior of Copper Octafluorophthalocyanine in an Organic Field-Effect Transistor
摘要： Based on the crystal structure analysis, the overlap integral between the frontier molecular orbitals of adjacent F8CuPcs in the one-dimensional chain is estimated: the overlap integral between the lowest unoccupied molecular orbitals is 5.4 × 10?3, which is larger than that in a typical n-type semiconducing material F16CuPc (2.1 × 10?3), whereas that between the highest occupied molecular orbitals is 2.9 × 10?4. Contrary to previous studies in air, we found that an organic field-effect transistor (OFET) composed of F8CuPc essentially shows clear n-type semiconducting behavior in vacuum.
关键词： n-type semiconductor,OFET,copper octafluorophthalocyanine,organic semiconductor
更新于2025-09-23 15:21:21
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Application of rubrene air-gap transistors as sensitive MEMS physical sensors
摘要： Micro electromechanical systems (MEMS) made of organic materials have attracted efforts on development a new generation of physical, chemical and biological sensors, for which the electromechanical sensitivity is the current major concern. Here, we present an organic MEMS made of a rubrene single crystal air-gap transistor. Applying mechanical pressure on the semiconductor results in high variations of drain current: an unparalleled Gauge factor above 4000 has been measured experimentally. Such a high sensitivity is induced by the modulation of charge injection at the interface between the gold electrode and the rubrene semiconductor as an unusual transducing effect. Applying these devices to the detection of acoustic pressure shows that force down to 230 nN can be measured with a resolution of 40 nN. This study demonstrates that MEMS based on rubrene air-gap transistors constitute a step forward to the development of high performance flexible sensors.
关键词： crystal,charge injection,organic MEMS,pressure sensor,air-gap transistor,OFET,rubrene
更新于2025-09-23 15:21:21
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Synthesis, and spectroscopic, thermal and dielectric properties of phosphazene based ionic liquids: OFET application and tribological behavior
摘要： Mono(4-fluorobenzyl)cyclotriphosphazene derivatives with (dimethylamino)ethoxy (Pz1a–2a) and (dimethylamino)propoxy (Pz1b–2b) chains were synthesized. The chain nitrogen atoms of fully substituted cyclotriphosphazene compounds were quaternized by treatment with CH3I to give phosphazene based ionic liquids (PzILs), PzIL1–PzIL4. Subsequent metathesis with LiN(SO2CF3)2 gave the salts, PzIL1a–PzIL4a. The structures of the PzILs were confirmed by elemental analyses, FTIR and 1H, 13C{1H}, and 31P{1H} NMR techniques. The thermal properties of all compounds were described using thermogravimetric analysis (TGA). These newly synthesized PzILs were used as the dielectric layer in organic field effect transistors (OFETs). Both dielectric and OFET characterization were performed. Because of the high dielectric effect of the PzILs, the fabricated OFETs operated in the low voltage range. Furthermore, a sliding wear test was conducted at room temperature using an AA7075 disc specimen against a stationary 100Cr6 steel ball. The wear protection of the PzILs and 15W40 engine oil was determined by considering the volume loss of AA7075. The lowest coefficient of friction (COF) and wear loss were obtained with PzIL4a.
关键词： ionic liquids,dielectric properties,phosphazene,OFET,tribology,synthesis
更新于2025-09-19 17:15:36
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<i>N</i> -Cyanoimine as an electron-withdrawing functional group for organic semiconductors: example of dihydroindacenodithiophene positional isomers
摘要： Manipulating frontier molecular orbitals by chemical design is one of the chief aspects of organic electronics. For applications in the field of n-type organic field-effect transistors (OFET), depressing the LUMO energy level is particularly important to ensure efficient charge injection. In this work, we report the incorporation of electron-withdrawing cyanoimine functional groups on the bridges of dihydroindacenodithiophene regioisomers. Cyanoimines are barely known in the field of organic electronics but herein have been found to be highly efficient in depressing the LUMO energy level of an organic semiconductor and can thus be envisaged as an attractive alternative to widely known electron-withdrawing units such as dicyanovinylene. This work focuses on a detailed structure–property relationship study, including the incorporation in n-type OFETs, of two dihydroindacenodithiophene regioisomers bearing two cyanoimine groups either in a syn- or an anti-configuration. As far as we know, this work is only the second example reported to date on N-cyanoimines incorporated in n-type OFETs, and shows the potential of these functional groups in organic electronics.
关键词： organic semiconductor,dihydroindacenodithiophene,electron-withdrawing group,positional isomers,N-cyanoimine,n-type OFET
更新于2025-09-19 17:15:36
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Macroscopically oriented (3-pentadecyl phenol) dangled fluorene based conductive polymer through side chain engineering for microelectronics
摘要： In this paper, we have designed a solution processable macroscopically oriented conductive polymer of fluorene dangled 3-pentadecylphenol (Polyfluorene pentadecyl benzene, PFLPDB) through side chain engineering and self-assembly approach. Initially fluorene was coupled with 3-pentadecylphenol (3-PDP) and further subjected to oxidative polymerisation in the presence of anhydrous ferric chloride (FeCl3). Effects of polarity of the solvent and time on self-assembly process was studied using various microscopic techniques which suggested the formation of macroscopically oriented fibers having 20–30 nanometer diameter in chloroform with an electrical conductivity of (2.1·10–2 S·cm–1). Optical and electrochemical band gaps were calculated from the studies made by UV-Vis spectroscopy and cyclic voltammetry. Its field effect transfer characteristics were further studied by fabricating an Organic field effect transistor (OFET) device having configuration (Si/SiO2/PFLPDB/Ag) and measured its field effect mobility (1.076 cm2·v–1·s–1) at 1 V and ON/OFF ratio of the device calculated as 1.82·103 suggests its application as an excellent active material for organic microelectronics.
关键词： molecular engineering,macroscopically ordered,3-pentadecyl phenol dangled fluorene,OFET,polymer synthesis
更新于2025-09-16 10:30:52
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Azulene’s D–A Structure for Optoelectronic Materials
摘要： Azulene’s D–A Structure for Optoelectronic Materials
关键词： OFET,azulene,n-type polymers,all-polymer solar cell
更新于2025-09-04 15:30:14