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Flexible and stable organic field-effect transistors using low-temperature solution-processed polyimide gate dielectrics
摘要： Polyimide (PI) has been widely used as a gate dielectric due to its remarkable thermal stability, chemical resistance, and mechanical flexibility. However, the high processing temperature and high surface energy of PI gate dielectrics hinder the realization of flexible and reliable electronic applications with low-cost manufacturing. Here, a low-temperature solution-processed organic field-effect transistor (OFET) is successfully demonstrated using a fully imidized soluble PI gate dielectric. The low temperature processability of soluble PI gate dielectrics is confirmed by investigating the effect of annealing temperature on the dielectric properties and electrical characteristics. By blending 6,13-Bis(triisopropylsilylethynyl)pentacene with polystyrene, the reliability of OFET is considerably enhanced while maintaining high device performance. As a result, OFETs exhibit excellent flexibility and can be integrated with ultrathin parylene substrates without degrading device performance. This work presents the steps to develop flexible and reliable electronic applications with low-cost manufacturing.
关键词： organic field-effect transistors,solution-processed,polyimides,low-temperature,operational stability
更新于2025-11-14 15:19:41
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Performance improvement in photosensitive organic field effect transistor by using multi-layer structure
摘要： In this study, a new approach was introduced for Photo-OFETs as a multi-layer structure. Poly(3-hexylthiophene-2,5-diyl) regioregular (P3HT) and Copper(II) phthalocyanine (CuPc) thin films were used as two different active photo-absorber layers in the same device structure. Poly(methyl methacrylate) (PMMA) was used as a dielectric layer and all devices were fabricated with a top-gate bottom-contact configuration. In order to investigate the effect of the location of each layer on the Photoresponsive organic field-effect transistors (Photo-OFET) performance, five different devices in various structures were produced and analyzed. Surface properties of active layers have been investigated via Atomic Force Microscopy (AFM) and effects of surface roughness on device performance have been discussed. P3HT/CuPc/P3HT multi-layered structure exhibited the best performance in terms of photoresposivity(as 45 mA/W) and photosensitivity (~ 2x103). Photo-OFET based on a multi-layer structure demonstrated superior performance with wider absorbance spectrum region compared to conventional single component devices of P3HT or CuPc. The proposed multi-layer structure can be a model to improve the realization of high performance Photo-OFETs.
关键词： Photoresponsive organic field-effect transistors,Organic field effect transistors,Multilayer structure,Poly(3-hexylthiophene),Photosensitivity,Poly(methyl methacrylate)
更新于2025-09-23 15:23:52
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A New A-D-A’-D-A Conjugated Molecule Entailing Diazapentalene Unit for n-Type Organic Semiconductor
摘要： Conjugated molecules with low lying LUMO levels are demanding for the development of air stable n-type organic semiconductors. In this paper, we report a new A-D-A’-D-A conjugated molecule (DAPDCV) entailing diazapentalene (DAP) and dicyanovinylene groups as electron accepting units. Both theoretical and electrochemical studies manifest that the incorporation of DAP unit in the conjugated molecule can effectively lower the LUMO energy level. Accordingly, thin film of DAPDCV shows n-type semiconducting behaviour with electron mobility up to 0.16 cm2·V-1·s-1 after thermal annealing under N2 atmosphere. Moreover, thin film of DAPDCV also shows stable n-type transporting property in air with mobility reaching 0.078 cm2·V-1·s-1.
关键词： organic field-effect transistors,dicyanovinylene groups,n-type semiconductors,diazapentalene
更新于2025-09-23 15:23:52
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Nitrogen-embedded small-molecule semiconducting materials: Effect of chlorine atoms on their electrochemical, self-assembly, and carrier transport properties
摘要： We reported three novel nitrogen-embedded small molecules 4a, 4b, and 4c, which were synthesized from the condensation reactions of benzo[1,2-b:4,5-b']difuran-2,6(3H,7H)-dione with 1-(2-ethylhexyl)-1H-pyrrolo[2,3-b]pyridine-2,3-dione, 6-chloro-1-(2-ethylhexyl)-1H-pyrrolo[2,3-b]pyridine-2,3-dione, or 4,6-dichloro-1-(2-ethylhexyl)-1H-pyrrolo[2,3-b]pyridine-2,3-dione, respectively. Their optical, electrochemical properties, self-assembly behavior, and carrier transport properties were studied by a range of experimental and theoretical methods, and the effect of chlorine atoms were well discussed. Energy levels of the highest occupied molecular orbitals and the lowest unoccupied ones for these molecular materials locate at ?5.92～?6.02 and ?4.25～?4.37 eV, respectively. Bottom gate/bottom contact field-effect transistors based on 4a, 4b, and 4c exhibited n-channel transport characteristics with the highest electron mobility of 7.57 × 10?3 cm2 V?1 s?1. Thin film microstructure investigations revealed 4a and 4c perform lamellar molecular packing with random orientations to the OTS-treated SiO2 substrate, while 4b conducts a highly crystalline, edge-on, lamellar packing though large grain boundaries exist in its thin film.
关键词： Isoindigo derivatives,Chlorine atoms,Small-molecule semiconductors,Electron mobilities,Organic field-effect transistors
更新于2025-09-23 15:23:52
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Threshold Voltage Control in Organic Field-Effect Transistors by Surface Doping with a Fluorinated Alkylsilane
摘要： Doping is a powerful tool to control the majority charge carrier density in organic field-effect transistors and the threshold voltage of these devices. Here, a surface doping approach is shown, where the dopant is deposited on the prefabricated polycrystalline semiconducting layer. In this study, (tridecafluoro-1,1,2,2-tetrahydrooctyl)-trichlorosilane (FTCS), a fluorinated alkylsilane is used as a dopant, which is solution processable and much cheaper than conventional p-type dopants, such as 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). In this work, the depositions from the gas phase and from solution are compared. Both deposition approaches led to an increased conductivity and to a shift in the threshold voltage to more positive values, both of which indicate a p-type doping effect. The magnitude of the threshold voltage shift could be controlled by the FTCS deposition time (from vapor) or FTCS concentration (from solution); for short deposition times and low concentrations, the off current stayed constant and the mobility decreased only slightly. In the low doping concentration regime, both approaches resulted in similar transistor characteristics, i.e., similar values of shift in the threshold and turn-on voltage as well as mobility, ION/IOFF ratio and amount of introduced free charge carriers. In comparison with vapor deposition, the solution-based approach can be conducted with less material and in a shorter time, which is critical for industrial applications.
关键词： self-assembled monolayers,fluorinated alkylsilanes,organic field-effect transistors,surface doping,p-type doping
更新于2025-09-23 15:23:52
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Organic Field-Effect Transistor Based Ultrafast, Flexible, Physiological Temperature Sensors with Hexagonal Barium Titanate Nanocrystals in Amorphous Matrix as Sensing Material.
摘要： Organic field-effect transistors (OFETs) with hexagonal barium titanate nanocrystals in amorphous matrix (h-BTNC) as one of the bilayer dielectric system have been fabricated on a highly flexible 10 μm thick polyethylene terephthalate (PET) substrates. The device current and mobility remains same upto a bending radius of 4mm that make it suitable for wearable e-skin applications. h-BTNC films found to be highly temperature sensitive and the OFETs designed based on this material showed ultra-precession (~4.3 mK), low power (~ 1μW at 1.2 V operating voltage), ultrafast response (~24 ms) in sensing temperature over a range from 20 °C to 45 °C continuously. The sensors are highly stable around body temperature and work at various extreme conditions, such as under water, solutions of different pH as well as of various salt concentrations. These properties make this sensor very unique and highly suitable for various healthcare and other applications, where in a small variation of temperature around this temperature range is required to be measured at an ultra-fast speed.
关键词： low power OFETs,electronic skin,temperature sensors,organic field-effect transistors,flexible sensors,healthcare sensors
更新于2025-09-23 15:23:52
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Electrical Detection of Singlet Fission in Single Crystal Tetracene Transistors
摘要： We present the electrical detection of singlet fission in tetracene by using a field-effect transistor (FET). Singlet fission is a photo-induced spin-dependent process, yielding two triplet excitons from the absorption of a single photon. In this study, we engineered a more deterministic platform composed of an organic single crystal FET rather than amorphous or polycrystalline FETs to elucidate spin-dependent processes under magnetic fields. Despite the unipolar operation and relatively high mobility of single crystal tetracene FETs, we were able to manipulate spin dependent processes to detect magnetoconductance (MC) at room temperature by illuminating the FETs and tuning the bias voltage to adjust majority charge carrier density and trap occupancy. In considering the crystalline direction and magnetic field interactions in tetracene, we show the MC response observed in tetracene FETs to be the result of the singlet fission process.
关键词： organic field effect transistors,singlet fission,magnetoconductance,single crystalline organic semiconductors
更新于2025-09-23 15:22:29
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Tuning Contact Resistance in Top-Contact <i>p</i> -Type and <i>n</i> -Type Organic Field Effect Transistors by Self-Generated Interlayers
摘要： Contact resistance significantly limits the performance of organic field-effect transistors (OFETs). Positioning interlayers at the metal/organic interface can tune the effective work-function and reduce contact resistance. Myriad techniques offer interlayer processing onto the metal pads in bottom-contact OFETs. However, most methods are not suitable for deposition on organic films and incompatible with top-contact OFET architectures. Here, a simple and versatile methodology is demonstrated for interlayer processing in both p- and n-type devices that is also suitable for top-contact OFETs. In this approach, judiciously selected interlayer molecules are co-deposited as additives in the semiconducting polymer active layer. During top contact deposition, the additive molecules migrate from within the bulk film to the organic/metal interface due to additive-metal interactions. Migration continues until a thin continuous interlayer is completed. Formation of the interlayer is confirmed by X-ray photoelectron spectroscopy (XPS) and cross-section scanning transmission electron microscopy (STEM), and its effect on contact resistance by device measurements and transfer line method (TLM) analysis. It is shown that self-generated interlayers that reduce contact resistance in p-type devices, increase that of n-type devices, and vice versa, confirming the role of additives as interlayer materials that modulate the effective work-function of the organic/metal interface.
关键词： organic electronics,TLM,self-generated interlayers,organic field-effect transistors
更新于2025-09-23 15:22:29
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Tertiary Amines Differentiated from Primary and Secondary Amines by Active Ester-Functionalized Hexabenzoperylene in Field Effect Transistors
摘要： Herein, we report two novel derivatives of hexabenzoperylene (HBP) that are functionalized with ester groups. Methyl acetate functionalized HBP (1) in single crystals self-assembles into a supramolecular nanosheet, which has a two-dimensional π-stack of HBP sandwiched between two layers of ester groups. With the same self-assembly motif, active ester-functionalized HBP (2) in field effect transistors has enabled differentiation of tertiary amines from primary and secondary amines, in agreement with the fact that active ester reacts with primary and secondary amines but not with tertiary amines to form amides.
关键词： sensors,organic field effect transistors,organic semiconductors,self-assembly,arenes
更新于2025-09-23 15:22:29
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Conjugated Polymers Based on Thiazole Flanked Naphthalene Diimide for Unipolar n-Type Organic Field-Effect Transistors
摘要： This paper reports the rational design and synthesis of a novel electron-withdrawing building block, thiazole flanked naphthalene diimide (TzNDI), which offers a coplanar conformation and deep-lying highest occupied molecular orbitals energy level in resulting conjugated polymers. A series of conjugated polymers (PTzNDI-2FT, PTzNDI-T, PTzNDI-Se, and PTzNDI-2T) consisting of TzNDI and different donor units were synthesized and characterized. The polymers all possess a high molecular weight and excellent thermal property. Their intense light absorption in low energy bands suggests an enhanced intramolecular charge transfer. The organic field-effect transistors (OFETs) based on these polymers exhibit unipolar n-type transport characteristics with low off current and high on–off current ratio. More importantly, all the devices exhibit near ideal transfer curves with kink-free transfer characteristics. Among these polymers, PTzNDI-2FT exhibits the highest electron mobility (μe) of 0.57 cm2 V?1 s?1, outperforming the commercial n-type polymer N2200 (0.41 cm2 V?1 s?1) under the same conditions. These results demonstrate that TzNDI is a promising building block for high performance unipolar n-type conjugated polymers in OFETs.
关键词： Unipolar n-Type,Thiazole Flanked Naphthalene Diimide,Conjugated Polymers,Organic Field-Effect Transistors
更新于2025-09-23 15:21:21