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A Noble Metal Dichalcogenide for High‐Performance Field‐Effect Transistors and Broadband Photodetectors
摘要： 2D layered materials are an emerging class of low-dimensional materials with unique physical and structural properties and extensive applications from novel nanoelectronics to multifunctional optoelectronics. However, the widely investigated 2D materials are strongly limited in high-performance electronics and ultrabroadband photodetectors by their intrinsic weaknesses. Exploring the new and narrow bandgap 2D materials is very imminent and fundamental. A narrow-bandgap noble metal dichalcogenide (PtS2) is demonstrated in this study. The few-layer PtS2 field-effect transistor exhibits excellent electronic mobility exceeding 62.5 cm2 V?1 s?1 and ultrahigh on/off ratio over 106 at room temperature. The temperature-dependent conductance and mobility of few-layer PtS2 transistors show a direct metal-to-insulator transition and carrier scattering mechanisms, respectively. Remarkably, 2D PtS2 photo detectors with broadband photodetection from visible to mid-infrared and a fast photoresponse time of 175 μs at 830 nm illumination for the first time are obtained at room temperature. Our work opens an avenue for 2D noble-metal dichalcogenides to be applied in high-performance electronic and mid-infrared optoelectronic devices.
关键词： broadband photodetection,PtS2,on-off ratio,field-effect transistors,mobility
更新于2025-09-12 10:27:22
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Influences of Energetically Controlled Dielectric Functionality on Polymer Field-Effect Transistor Performance
摘要： We systematically demonstrated the effects of surface modification of gate dielectrics and the thermal annealing of an ad-deposited polymer semiconducting film on the electrical performance of organic field-effect transistors (OFETs) in which they were incorporated. Chemically or energetically engineered dielectrics were designed by introducing various end-functional groups (CF3, CH3, NH2, Cl, and SH). Poly(dioctyl-quaterthiophene-dioctyl-bithiazole) (PDQDB), consisting of 5,5 ′ -bithiazole and oligothiophene rings, was employed as the polymer semiconductor. We analyzed the PDQDB semiconducting films’ crystalline character, which has an important effect on the FET performance, and confirmed that the crystallinity of the PDQDB semiconducting films was higher in the cases (CF3 and CH3) of low surface energy than in the cases (NH2, SH, and Cl) of high surface energy, yielding μFET values as high as 0.13 and 0.12 cm2 V?1 s?1 for the CF3 and CH3 cases, respectively. Another important observation was the tendency of the μFET value to change depending on the thermal annealing temperature—increasing and decreasing in the cases of surface functionalities with low and high surface energies, respectively. These results could be interpreted on the basis of the differently competitive molecule–molecule and molecule–dielectric surface interactions, where the π–π stacking configuration of the conjugated molecular structures was enhanced on lower-energy surfaces. We also discussed the effect of permanent dipoles for the engineered self-assembled monolayer dielectrics on the threshold and turn-on voltages in the PDQDB FET devices.
关键词： thermal annealing,surface modification,polymer semiconductor,organic field-effect transistors,dielectric functionality
更新于2025-09-12 10:27:22
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Optically controlled field effect transistors based on photochromic spiropyran and fullerene C60 films
摘要： Optically controlled organic field effect transistors containing a binary mixture of fullerene C60 (n-semiconductor) and spiropyran (photoresponsive conductivity modulator) as the active layer were designed and fabricated. The obtained transistors demonstrated higher transfer characteristics (source-drain current), charge carrier mobility in the active layer, and response rate to an external influence than the multilayer transistor (wherein these semiconductor and photo responsive material are in different layers), which makes them promising candidates for the design of optical memory elements.
关键词： Optically controlled field effect transistors,photochromic spiropyran,fullerene C60,optical memory elements
更新于2025-09-12 10:27:22
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A Machine‐Learning Based Design Rule for Improved Open‐Circuit Voltage in Ternary Organic Solar Cells
摘要： Organic solar cells (OSCs) based on ternary blend active layers are among the most promising photovoltaic technologies. To further improve the power conversion efficiency (PCE), the materials selection criteria must be focused on achieving high open-circuit voltage (Voc) through the alignment of the energy levels of the ternary blend active layers. Hence, machine-learning approaches are in high demand for extracting the complex correlation between Voc and the energy levels of the ternary blend active layers, which are crucial to facilitate device design. In the present work, the data-driven strategies are used to generate a model based on the available experimental data and the Voc are then predicted using available machine-learning methods (Random Forest regression and Support Vector regression). In addition, the Random Forest regression is compared with Support Vector regression to demonstrate the superiority of Random Forest regression for Voc prediction. The Random Forest regression is then developed to find the appropriate energy level alignment of ternary OSCs and to reveal the relationship between Voc and electronic features. Finally, an analysis based on the ranking of variables in terms of importance by the Random Forest model is performed to identify the key feature governing the Voc and the performance of ternary OSCs. From the perspective of device design, the machine-learning approach provides sufficient insights to improve the VOC and advances the comprehensive understanding of ternary OSCs.
关键词： organic field-effect transistors,Machine-learning,charge transport mobility.
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - St. Petersburg, Russia (2019.10.17-2019.10.18)] 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - The Multi-Criteria Optimization in the LTspice Simulation Software of a JFet class AB Buffer Amplifier for Operation at Low Temperatures
摘要： A high-speed buffer amplifier (BA) for analog microcircuits field-effect transistors is proposed. The scheme differs from the known circuit solutions by a small number of elements and can operate within the range of cryogenic temperatures. In the LTSpice simulation software, the optimal control parameters were selected using the DEAP (Distributed Evolutionary Algorithm in Python) library of distributed evolutionary calculations and the NSGA-II multi-criteria optimization algorithm. Minimization of offset voltage, static current consumption and dead band width on the amplitude characteristic at low temperatures were chosen as the priority parameters of the control unit.
关键词： low-temperature electronics,class AB operation,optimization of analog electronic circuit,operational amplifier,LTspice environment,buffer amplifier,junction field-effect transistors
更新于2025-09-12 10:27:22
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Effect of space charge limited current on performance of organic field-effect transistors
摘要： The crucial parameter that determines the performance of a semiconductor material in organic field-effect transistors (OFETs) is the charge carrier mobility. The conventional method of its determination based on Shockley’s equations can lead to incorrect mobility evaluation due to contact effects. Particularly, in the common staggered OFET architecture (top-contact bottom-gate or bottom-contact top-gate), the space-charge limited current (SCLC) effect in the active layer under/above the source and drain contacts decreases the source-drain current. In this work, we model the effect of SCLC under/above the source and drain electrodes on the OFET apparent mobility (i.e., calculated from the device characteristics) and apparent threshold voltage for different active layer thickness and intrinsic mobility anisotropy. For the saturation regime, we derived simple analytical expressions for transfer characteristics and apparent mobility. Our modeling shows that the apparent OFET mobility is more than five times lower than the intrinsic one for the active layer thicker than 100 nm with mobility anisotropy (along vs across the active layer) higher than 100. While the SCLC effect does not change the apparent threshold voltage, it reveals itself as a kink at near zero voltage in the output characteristics. The proposed model gives analytical expressions for the transfer characteristics and apparent mobility as explicit functions of the intrinsic mobility and the device parameters in the saturation regime and as implicit functions in the linear regime. Our findings provide guidelines for accurate evaluation of the intrinsic mobility in OFETs fabricated in the staggered architecture and for further improvement of OFET performance.
关键词： Organic field-effect transistors,Organic thin-film transistors,Space charge limited current,Contact effects,Modeling
更新于2025-09-11 14:15:04
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Layer-Dependent Optoelectronic Properties of 2D van der Waals SnS Grown by Pulsed Laser Deposition
摘要： Layered metal monochalcogenides have attracted significant interest in the 2D family since they show different unique properties from their bulk counterparts. The comprehensive synthesis, characterization, and optoelectrical applications of 2D-layered tin monosulfide (SnS) grown by pulsed laser deposition are reported. Few-layer SnS-based field-effect transistors (FETs) and photodetectors are fabricated on Si/SiO2 substrates. The premium 2D SnS FETs yield an on/off ratio of 3.41 × 106, a subthreshold swing of 180 mV dec?1, and a field effect mobility (μFE) of 1.48 cm2 V?1 s?1 in a 14-monolayer SnS device. The layered SnS photodetectors show a broad photoresponse from ultraviolet to near-infrared (365–820 nm). In addition, the SnS phototransistors present an improved detectivity of 9.78 × 1010 cm2 Hz1/2 W?1 and rapid response constants of 60 ms for grow-time constant τg and 10 ms for decay-time constant τd under extremely weak 365 nm illumination. This study sheds light on layer-dependent optoelectronic properties of 2D SnS that promise to be important in next-generation 2D optoelectronic devices.
关键词： phototransistors,field effect transistors,2D materials,tin monosulfide,p-type FETs
更新于2025-09-11 14:15:04
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Ambipolar and Robust WSe <sub/>2</sub> Field‐Effect Transistors Utilizing Self‐Assembled Edge Oxides
摘要： Transition metal oxides (TMOs) with high work function (WF) show promising properties as unipolar p-type contacts for transition metal dichalcogenides. Here, ambipolar field-effect transistors (FETs) enabled by bilayer WSe2 with self-assembled TMOs (WO2.57) as contacts are reported. Systematic material characterizations demonstrate the formation of WO2.57/WSe2 heterojunctions around nanoflake edges with Se atoms substituted by O atoms after air-exposure, while pristine properties of WSe2 almost sustain in inner domains. As-fabricated FETs exhibit both polarities, implying WO2.57 with lowered WF at edges can serve as both the p-type and n-type contact for inner WSe2. Noteworthy, greatly reduced contact resistance and enhanced channel current are achieved, compared to the devices without WO2.57 contacts. Linear drain–source current relationship from 77 to 300 K indicates the ohmic contact between edge WO2.57 and inner WSe2. Density functional theory calculations further reveal that the WO2.57/WSe2 heterojunction forms a barrier-less charge distribution. These nm-scale FETs possess remarkable electrical conductivity up to ≈2600 S m?1, ultra-low leakage current down to ≈10?12 A, robustness for high voltage operation, and air stability, which even outperform pristine WSe2 FETs. Theoretical calculations reveal that the high conductivity is exclusively attributed to the air-induced WO2.57 and its further carrier injection to WSe2.
关键词： field-effect transistors,self-passivation,WOx,density functional theory,WSe2
更新于2025-09-11 14:15:04
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Highly sensitive air stable easily processable gas sensors based on Langmuir-Schaefer monolayer organic field-effect transistors for multiparametric H <sub/>2</sub> S and NH <sub/>3</sub> real-time detection
摘要： A combination of low limit of detection, low power consumption and portability makes organic field-effect transistors (OFETs) chemical sensors promising for various applications in the areas of industrial safety control, food spoilage detection and medical diagnostics. However, the OFET sensors typically lack air stability and restoration capability at room temperature. Here we report on a new design of highly sensitive gas sensors based on Langmuir-Schaefer monolayer organic field-effect transistors (LS OFETs) prepared from organosilicon derivative of [1]benzothieno[3,2-b][1]-benzothiophene. The devices fabricated are able to operate in air and allows an ultrafast detection of different analytes at low concentrations down to tens ppb. The sensors are reusable and can be utilized in real-time air quality monitoring systems. We show that a direct current response of the LS OFET can be splitted into the alteration of various transistor parameters, responsible for the interactions with different toxic gases. The sensor response acquiring approach developed allows distinguishing two different gases, H2S and NH3, with a single sensing device. The results reported open new perspectives for the OFET-based gas-sensing technology and pave the way to easy detection of the other types of gases enabling the development of complex air analysis systems based on a single sensor.
关键词： Multiparametric detection,Sensing mechanism,Monolayer organic field-effect transistors,Langmuir-Schaefer monolayers,Chemical sensors
更新于2025-09-11 14:15:04
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Engineered Nano-Structured Virus/ZnO Hybrid Materials with Dedicated Functional Properties
摘要： Bio-inspired mineralization for the production of new functional materials offers mild reaction conditions suitable to integrate biological templates and build hierarchically organized hybrid nanostructures with defined properties. In this respect, tobacco mosaic virus (TMV) stands out due to its unique structural dimensions. Here, we present a novel mineralization pathway for synthesis of virus-based ZnO hybrids with multifunctional properties. Wild-type TMV (wt-TMV), two TMV mutants (E50Q and TMV-Cys) and amino-functionalized self-assembled monolayers (NH2-SAMs), as a reference, were used as templates. This mineralization approach allows control of the particle size of the inorganic phase. Further, the virus contributes additionally to the texturing of ZnO. Field effect transistors (FETs) built from the hybrid films showed reproducible results at optimized conditions at close to ambient conditions and without post-treatment. The significantly reduced threshold voltage of the E50Q/ZnO FET compared to NH2-SAMs/ZnO FET points to the impact of the organic template on FET performance. Nacre-like virus-based ZnO multilayers and corresponding monolithic references were prepared. The mechanical properties by means of Young’s modulus, hardness and fracture toughness were determined and an increase of the mechanical performance by genetic modification was observed.
关键词： field effect transistors,Bio-inspired mineralization,ZnO hybrids,mechanical properties,tobacco mosaic virus
更新于2025-09-11 14:15:04