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Dithienobenzothiadiazole-Based Donor-Acceptor Polymer: Synthesis and Characterization for Organic Field-Effect Transistor
摘要： Conjugated polymers with coplanar conformation backbones can form a closer π-π stacking self-assembly in solid films, producing high charge-carrier mobility in organic field-effect transistors (OFETs). In this work, a new donor-acceptor (D-A) copolymer (PDTFBT-TVT) including (E)-2-(2-(thiophen-2-yl)vinyl)thiophene and dithienobenzothiadiazole conjugated units is synthesized via Stille copolymerization. It is found that PDTFBT-TVT has a good planar backbone structure with an optical band gap of 1.89 eV. Spun-cast film contains preferentially edge-on orientated polymer chains with respect to a polymer-treated SiO2 dielectric, yielding a hole mobility (μh) of 0.06 cm2 V-1 s-1 in OFET. Thermal annealing enhanced the π-conjugated ordering and orientation of PDTFBT-TVT chains in the spun-cast films. The annealed film-based OFETs show a considerable enhancement in μh up to 0.22 cm2 V-1 s-1, as well as high on/off current ratio of > 106.
关键词： organic field-effect transistor,donor-acceptor copolymer,dithienobenzothiadiazole
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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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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Organic Transistor Based on Cyclopentadithiophene-Benzothiadiazole Donor-Acceptor Copolymer for the Detection and Discrimination between Multiple Structural Isomers
摘要： Distinguishing structural isomers is a critical and challenging task for biotechnology, chemical industry, and environmental monitoring. Approaches currently available are limited in terms of selectivity and simplicity. In this paper, a highly sensitive organic field-effect transistor (OFET) using the cyclopentadithiophene-benzothiadiazole (CDT-BTZ) copolymers as a semiconductor is presented for easy and selective detection of different families of structural isomers, as well as between different isomers within each family. High accuracy discrimination is achieved over a range of concentrations using only a single sensing parameter derived from the OFET characteristic transfer curve. As a reference, other homopolymer- and donor–acceptor copolymer-based OFET sensors are examined but do not have an equivalent sensing performance to that of the CDT-BTZ-based OFETs. Investigating the link between isomer absorption and swelling, supramolecular order and energy levels of the active layer reveals a unique effect of each isomer on the energy bands of the semiconducting polymer.
关键词： isomers,donor–acceptor copolymers,gas sensor,organic field-effect transistor,xylenes
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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Impact of oxide/barrier charge on threshold voltage instabilities in AlGaN/GaN metal-oxide-semiconductor heterostructures
摘要： Threshold voltage instabilities in AlGaN/GaN metal-oxide-semiconductor (MOS) heterostructures were investigated by means of capacitance-voltage (CV) hysteresis measurement and simulations. We focused on the impact of net charge at oxide/semiconductor interface (Qint) on the CV hysteresis. Our simulations suggest that due to different band bending at the interface, any positive or negative Qint with lower density (in the order of 1012 cm?2) results in a presence of relatively shallow unoccupied oxide/barrier interface states in equilibrium. On the other hand, high density of negative Qint (Qint/q ≈ ?1013 cm?2) results in very deep unoccupied interface states, which in turn leads to incomplete electron re-emission during backward CV sweep and thus increased CV hysteresis of the MOS heterostructures compared to previous case. Impact of Qint is illustrated experimentally on MOS heterostructures with Al2O3 gate dielectric grown by metal-organic chemical vapor deposition, showing Qint of ?1.2 × 1013 and +0.5 × 1012 cm?2 for structures with and without post-deposition annealing, respectively. Our results therefore suggest that normally-off AlGaN/GaN MOS heterostructure field-effect transistors featuring high density of negative Qint can be expected to be more susceptible for threshold voltage instabilities compared to normally-on counterparts.
关键词： MOS,Al2O3 gate dielectric,Heterostructure field-effect transistor,Interface traps,AlGaN/GaN
更新于2025-09-23 15:23:52
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Optical memory characteristics of solution-processed organic transistors with self-organized organic floating gates for printable multi-level storage devices
摘要： Exploring optical memory functions in nonvolatile organic field-effect transistor (OFET) memories with top-gate/bottom-contact (TG/BC) configurations can offer effective routes for developing printable, high-density organic memory circuits capable of multi-level data storage. Here, we use a solution process to fabricate TG/BC OFET devices with organic floating-gate structures and investigate their memory characteristics under light illumination. A solution-processable organic composite of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) and poly(methylmethacrylate) is employed to self-organize organic floating-gate structures on a solution-processed semiconductor layer composed of poly(3-hexylthiophene) (P3HT). The floating-gate OFET devices programmed with blue, green, and red light exhibit large threshold voltage (Vth) shifts of approximately 30 V and stable charge retention characteristics even under light illumination. The devices also exhibit high sensitivity to incident light during programming, and the degree of Vth shift and the on-state current can be tuned using light and programming voltage to facilitate distinct storage and readout of multi-level data.
关键词： floating-gate memory,organic field-effect transistor,top-gate/bottom-contact configuration,multi-level data storage,solution-processable organic material
更新于2025-09-23 15:23:52
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The influences of temperature, humidity, and O2 on electrical properties of graphene FETs
摘要： The influences of temperature, humidity, and O2 to the gas sensing characteristics of graphene field effect transistors (FETs) have been studied as these environmental factors are often encountered in practical gas sensing applications. Both empirical results and theoretical analyses are characterized for heated graphene FET gas sensors from room temperature to 100°C under a wide range of applied gate voltages. It is found that at a constant applied gate voltage of -20 V with respect to the gate voltage at the neutrality point, the sensitivity of the device to humidity decreases; while the sensitivity to O2 decreases first, and increases afterwards as the operation temperature increases. These phenomena are explained by using the physisorption and chemisorption models between gases and the graphene surface. Furthermore, devices operate in the hole regime (the majority carrier is hole in the prototype devices) result in lower sensitivity to humidity and O2 as compared to those results of gas sensors operating in the electron regime due to the p-type doping effects of moisture and O2. As such, this work provides good foundations for graphene-based FET gas sensors in practical application environments under the influences of ambient air, temperature, and humidity.
关键词： ambient air,gas sensor,temperature,Graphene field effect transistor,humidity,oxygen
更新于2025-09-23 15:23:52
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Device noise reduction for silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate
摘要： The sensitivity of metal-oxide-semiconductor field-effect transistor (MOSFET) based nanoscale sensors is ultimately limited by noise induced by carrier trapping/detrapping processes at the gate oxide/semiconductor interfaces. We have designed a Schottky junction gated silicon nanowire field-effect transistor (SiNW-SJGFET) sensor, where the Schottky junction replaces the noisy oxide/semiconductor interface. Our sensor exhibits significantly reduced device noise, 2.1×10-9 V2μm2/Hz at 1 Hz, compared to reference devices with the oxide/semiconductor interface operated at both inversion and depletion modes. Further improvement can be anticipated by wrapping the nanowire by such a Schottky junction thereby eliminating all oxide/semiconductor interfaces. Hence, a combination of the low-noise SiNW-SJGFET device with a sensing surface of the Nernstian response limit holds promises for future high signal-to-noise ratio sensor applications.
关键词： Noise reduction,field-effect transistor,ion sensor,low frequency noise,schottky junction gate,silicon nanowire
更新于2025-09-23 15:23:52