A new imidazolylquinoline for organic thin film transistor

A new active electronic material, 2-(naphtho[3,4]imidazol-2-yl)quinoline (NIQ), 1, has been synthesized and fully characterized. This compound exhibits field-effect carrier mobility and behaves as a p-type semiconductor (μ_FET = 0.148 cm²/V s at V_DS = 10 V). NIQ and its related imidazolylquinoline compounds may have possible applications as active materials in organic thin film transistors.     

十二烷基磺酸钠场效应晶体管化学传感器的研究

用十六烷基三甲基溴化铵和β－环糊精作为电活性物质,制成了十二烷基磺酸离子敏感场效应晶体管化学传感器。其输出栅压ＶＧｏｕｔ和待测离子浓度的关系符合能斯特方式程。该传感器用于十二烷基磺酸钠浓度的检测,检出限达１．００＊１０＾－６ｍｏｌ／Ｌ。     

四(十二烷基)碘化铵-氯酸根FET传感器的研究

报道了以四(十二烷基)碘化铵作为电活性物质,对氯酸根离子响应的场效应晶体管化学传感器(氯酸根FET)。传感器电位响应的线性范围为1.00×10-1mol/L～3.98×10-6mol/L,斜率为55.0mV/pC,适应pH范围为3.5～10 0。该传感器全固态化、自身阻抗变换、易于微型化和集成化,已用于测定氯酸根离子。     

Charge carrier transport in high purity perylene single crystal studied by time-of-flight measurements and through field effect transistor characteristics

Electronic transport has been studied by measuring the characteristics of field effect transistors using high purity perylene and the results have been compared with those from time-of-flight measurements. The purity of the material has been monitored by carrier trapping time and delayed fluorescence lifetime. Three types of field effect transistors have been studied: (1) thin film transistor, (2) transistor prepared by placing a single crystal flake on a substrate and (3) transistor fabricated on a single crystal by depositing electrodes and insulating layer onto it. Compared to thin film transistors prepared by evaporating perylene onto a SiO₂/Si substrate, higher mobility values were obtained with transistors using single crystals, but the electrical characteristics of the transistors were far from ideal: large threshold gate voltage observed in the second class of FETs indicated that a high density of traps are present at the interface between the organics and the insulator. A transistor of the third class showed that it functioned indeed as a FET with a reasonably high mobility, but the operation was not stable enough to allow reliable measurements. Much remains to be improved in the design and construction of a perylene FET before the potentiality of the material is fully developed. Also, it remains to be explored to what extent the bulk purity and the molecular order at the organics/insulator interface influence the transport of the charge carriers in an organic FET.     

超分子在质量敏感压电化学传感器中的应用

以质量敏感为分析基础的压电化学传感器,其表面涂层往往决定其对分析物的选择性。超分子作为压电石英晶体涂层,应用主－客体分子识别的原理,显著提高压电化学传感器的选择性。该文详细论述了近十年有关超分子主体化合物在体波和表面波化学传感器的应用,并了涂膜技术及主－客体识别机理。     

High Performance of Enhanced Mode Field Effect Transistor and Ultraviolet Sensor Based on ZnO Nanosheet

ZnO nanosheets with thickness of a few nanometers are prepared by vapor transport and condensation method, and their structure and optical properties are well characterized. Field effect transistor (FET) and ultraviolet (UV) sensors are fabricated based on the ZnO nanosheets. Due to the peculiar structure of nanosheet, the FET shows n-type enhanced mode behavior and high electrical performance, and its field-effect mobility and on/off cur-rent ratio can reach 256 cm²/(V·s) and ～10⁸, respectively. Moreover, the response of UV sensors can also be remarkably improved to ～3×10⁸. The results make the ZnO nanosheets be a good material for the applications in nanoelectronic and optoelectronic devices.     

有机半导体图案化成膜中的马兰戈尼与咖啡环效应协同作用

有机场效应晶体管在柔性传感和显示驱动应用中展示出极大的潜力,但在大面积制备高性能有机薄膜及有机场效应晶体管方面仍面临大的挑战。本文介绍了一种利用等离子处理和马兰戈尼-咖啡环效应协同作用来图案化生长有机半导体薄膜的方法。经过对等离子体处理时间、混合溶剂的比例及溶液浓度等生长条件优化,在5 cm×5 cm的基片上得到了覆盖性较为完整的2,7-二辛基[1]苯并噻吩并[3,2-b]苯并噻吩(C8-BTBT)薄膜阵列。基于此薄膜构筑了底栅顶接触晶体管阵列,器件的平均迁移率达到7.9 cm~2·V~(-1)·s~(-1),阈值电压均小于-2 V,开关电流比大于10~4。本工作对未来大面积制备高性能有机半导体薄膜及晶体管具有一定的借鉴意义。     

AFM,ellipsometry, XPS and TEM on ultra-thin oxide/polymer nanocomposite layers in organic thin film transistors

Here we report on the fabrication and characterization of ultra-thin nanocomposite layers used as gate dielectric in low-voltage and high-performance flexible organic thin film transistors (oTFTs). Reactive sputtered zirconia layers were deposited with low thermal exposure of the substrate and the resulting porous oxide films with high leakage currents were spin-coated with an additional layer of poly-α-methylstyrene (PαMS). After this treatment a strong improvement of the oTFT performance could be observed; leakage currents could be eliminated almost completely. In ellipsometric studies a higher refractive index of the ZrO₂/PαMS layers compared to the “as sputtered” zirconia films could be detected without a significant enhancement of the film thickness. Atomic force microscopy (AFM) measurements of the surface topography clearly showed a surface smoothing after the PαMS coating. Further studies with X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) also indicated that the polymer definitely did not form an extra layer. The polymer chains rather (self-)assemble in the nano-scaled interspaces of the porous oxide film giving an oxide–polymer “nanocomposite” with a high oxide filling grade resulting in high dielectric constants larger than 15. The dielectric strength of more than 1 MV cm⁻¹ is in good accordance with the polymer-filled interspaces.     

Environmental significance of wearable sensors based on MXene and graphene

Conductive layered materials such as MXenes (e.g., transition metal carbides, nitrides, and carbonitrides), graphene and their derivatives have attracted tremendous research interests in diverse fields of research for their unique structured merits and outstanding physical and chemical properties. Benefitting from their unique layered structures and fascinating multifunctional characteristic, MXenes and graphene serve as vital components in a variety of wearable devices. Especially, due to their large surface area and high electrocatalytic activity, these materials have also demonstrated great promise in biophysical and biochemical sensing systems. Following an introduction into the field, we summarize the recent progress in wearable sensors that can be accomplished by using layered materials, with a specific focus on kinematic, mechanical, thermal, pressure and strain sensors. A further large section underscores the recent progress in MXenes and graphene based wearable biochemical sensors including electrolyte monitoring, glucose monitoring, micro/mcromolecular organics metabolite, volatile gases monitoring and humidity sensors. The next section covers the sensing of small biomolecules serving as biomarkers, which are of great significance for early diagnosis and treatment of a spectrum of diseases. This review underscores the recent progress in wearable sensors to be used in different physiological and environmental signals. Finally, the review concludes with a debate on current challenges being faced and future perspectives.     

The influence of electrode metals and its configuration on the response of tin oxide thin film CO sensor

Thin films of tin oxide were deposited by electron beam evaporation. The effects of the electrode materials (Ag, Al, Au and Pt) and different electrode configurations on the CO-sensing of tin oxide thin films were investigated. The Pt and Au electrodes with bottom electrode configuration show much higher response than Ag and Al electrodes. The sensor response and recovery times have also been measured. The films were characterized using X-ray diffraction and X-ray photoelectron spectroscopy. All the films were found to be amorphous. It was found that the CO-sensing properties depend both on the electrode materials and configuration.     

A glucose sensor via stable immobilization of the GOx enzyme on an organic transistor using a polymer brush

Recently, there has been significant research in the area of organic electrochemical transistors (OECTs) because of their superior aptitude of chemical and biological sensing. Here it is shown for the first time the incorporation of polymer brushes to a transistor. Polymer brushes were chosen for their biocompatible properties and their ability to covalently tether enzymes and other biomolecules to different surfaces. OECTs were fabricated from the conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate), PEDOT:PSS, and polymerized from the surface a mixed polymer brush of poly(glycidyl methacrylate) and poly(2-hydroxyethyl methacrylate). The brushes were functionalized with glucose oxidase and measured in terms of electrical performance and long-term stability. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 372–377     

Optical waveguide sensor of volatile organic compounds based on PTA thin film

In this study, a sensitive optical waveguide (OWG) sensor for the detection and identification of volatile organic compounds (VOCs) was reported. The sensing membrane is constructed by immobilization of peroxopolytungsten acid (PTA) thin film over a single-mode potassium ion (K⁺) exchanged glass OWG by spin-coating method. A laser beam was coupled into and out of the glass optical waveguide using prism couplers, and dry air functioned as a carrier gas. The sensor was tested for various volatile organic compounds (VOCs), and it showed higher response to the chlorobenzene gas compared to other VOCs. Therefore, we used the OWG sensor to detect chlorobenzene gas as a typical example of VOCs. The sensor exhibits a linear response to chlorobenzene gas in the range of 0.4-1000 ppm with rapid response and good reversibility. The constructed sensor is easy to fabricate and it has some unique qualities which can be characterized as inexpensive, sensitive, and reusable.     

Synthesis and characterization of a novel polymer based on anthracene moiety for organic thin film transistor

We have designed and synthesized a new polymer, which could be used in the organic thin film transistor (OTFT). Poly[2,6‐bis(3′‐dodecythiophene‐2′‐yl)anthracene] (PDTAn), which is composed with anthracene moiety and dodecyl alkyl thiophene, was synthesized by oxidative polymerization using iron (III) chloride. The mole ratio of FeCl₃ and monomer (4.2:1), keeping low temperature during the initiation reaction, amount of solvent, and dropping order were very important for oxidative polymerization without crosslinking. The molecular weight of the polymer (M_w) was measured to be 40,000 with 2.85 of polydispersity index by GPC. The physical and optical properties of the polymer were characterized by differential scanning calorimetry (DSC), cyclic voltammetry (CV), and optical absorption and photoluminescence (PL) spectroscopy. A field‐effect mobility of 1.1 × 10^?4 cm² V^?1 S^?1, a current on/off ratio of 10⁵, and the V_th at ?15.2 V had been obtained for OTFTs using this polymer semiconductor by solution coating. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5115–5122, 2008     

聚(茚并芴-三苯胺)的合成及性能

设计并合成了一类新的可用于有机场效应晶体管(OFET)的聚合物半导体材料聚(茚并芴-三苯胺)(pIFTPA1~4), 通过核磁共振谱和凝胶渗透色谱等对聚合物进行了表征, 同时对其场效应薄膜晶体管性能进行了测试. 结果表明, 这些聚合物形成了无定形半导体膜, 在空气中稳定, 其载流子迁移率远高于聚三苯胺(pTPA)类材料, 其中pIFTPA1载流子迁移率高达4×10^-2 cm²/(V·s), 开关比为10⁶.     

A method for the detection of alcohol vapours based on optical sensing of magnesium 5,10,15,20-tetraphenyl porphyrin thin film by an optical spectrometer and principal component analysis

In this work we have proposed a method for the detection of alcohol vapours, i.e. methanol, ethanol and isopropanol, based on the optical sensing response of magnesium 5,10,15,20-tetraphenyl porphyrin (MgTPP) thin films, as measured by optical spectrometry with the assistance of chemometric analysis. We have implemented a scheme which allows a laboratory UV–vis spectrometer to act as a so-called “electronic nose” with very little modification. MgTPP thin films were prepared by a spin coating technique, using chloroform as the solvent, and then subjected to thermal annealing at 280 °C in an argon atmosphere. These MgTPP optical gas sensors presented significant responses with methanol compared to ethanol and isopropanol, based on the dynamic flow of alcohol vapours at the same mol% of alcohol concentration. Density functional theory (DFT) calculations were performed to model the underlying mechanism of this selectivity. The performance of the optical gas sensors was optimised by varying the fabrication parameters. It is hoped that the MgTPP thin film together with an off-the-shelf optical spectrometer and a simple chemometrics algorithm can be a valuable tool for the analysis of alcoholic content in the beverage industry.     

Field‐Effect Nanoparticle‐Based Glucose Sensor on a Chip: Amplification Effect of Coimmobilized Redox Species

A capacitive EIS (electrolyte‐insulator‐semiconductor) structure was modified with gold nanoparticles together with glucose oxidase and used as field‐effect‐based glucose biosensor using the constant capacitance mode. Co‐immobilization of ferrocene redox species resulted in a two‐fold increase of the biosensor sensitivity. The effect was explained by the hydrogen peroxide‐mediated oxidation of ferrocene resulting in a pool of charged species at the interface increasing the sensor response towards glucose. The studied approach was suggested as a general means to amplify signals from Si chip‐based field‐effect enzyme biosensors.     

Electrochemical sensing chemical oxygen demand based on the catalytic activity of cobalt oxide film

Cobalt oxide sensing film was in situ prepared on glassy carbon electrode surface via constant potential oxidation. Controlling at 0.8 V in NaOH solution, the high-valence cobalt catalytically oxidized the reduced compounds, decreasing its surface amount and current signal. The current decline was used as the response signal of chemical oxygen demand (COD) because COD represents the summation of reduced compounds in water. The surface morphology and electrocatalytic activity of cobalt oxide were readily tuned by variation of deposition potential, time, medium and Co²⁺ concentration. As confirmed from the atomic force microscopy measurements, the cobalt oxide film, that prepared at 1.3 V for 40 s in pH 4.6 acetate buffer containing 10 mM Co(NO₃)₂, possesses large surface roughness and numerous three-dimensional structures. Electrochemical tests indicated that the prepared cobalt oxide exhibited high electrocatalytic activity to the reduced compounds, accompanied with strong COD signal enhancement. As a result, a novel electrochemical sensor with high sensitivity, rapid response and operational simplicity was developed for COD. The detection limit was as low as 1.1 mg L⁻¹. The analytical application was studied using a large number of lake water samples, and the accuracy was tested by standard method.     

Synthesis and characterization of fused‐thiophene containing naphthalene diimide n‐type copolymers for organic thin film transistor and all‐polymer solar cell applications

Naphthalene diimide copolymers are attractive n‐type materials due to their high electron affinities, high electron mobilities, and exceptional stability. Herein, we report a series of NDI‐fused‐thiophene based copolymers with each copolymer differing in the number of fused thiophenes in the donor monomer. Increasing the number of fused‐thiophene moieties within an NDI‐copolymer backbone is shown to not only enable tuning of the electronic structure but also improve charge mobilities within the active layer of organic field‐effect transistors. Electron mobilities and on/off ratios as high as 0.012 cm² V^?1 s^‐1 and I_on/I_off > 10⁵ were measured from n‐channel thin‐film transistors fabricated using NDI‐xfTh copolymers. Bulk heterojunction solar cell devices were also fabricated from the NDI‐xfTh copolymer series in blends with poly(3‐hexylthiophene) (P3HT) with PNDI‐4fTh ‐ based devices yielding the largest J_sc (0.57 mA cm^?2) and fill factor (55%) in addition to the highest measured PCE for this series (0.13%). © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4061–4069     

Fabrication of ozone gas sensor based on FeOOH/single walled carbon nanotube-modified field effect transistor

A novel ozone (O₃) sensor is fabricated using commercial metal oxide field effect transistor (MOSFET), modified with single-walled carbon nanotubes (SWCNTs). In this study, integrated circuit (IC: BS250) was selected as the selective probe for O₃ detection. For this purpose, a plastic cover on the surface of the drain was drilled to bare the drain surface, followed by its modification with nitrogen and sulfur-functionalized SWCNTs by chemical vapor deposition (CVD) process. The CVD-synthesized SWCNTs were then electrodeposited with FeOOH nanostructures. According to the figures of merit, the fabricated sensor gave a linear output from 20 to 450 parts per billion (ppb). Detection limit was also 4.1?ppb. Relative standard deviation (RSD) for seven replicate analyses was 3.61%. Based on 90% of maximum response (t₉₀), the response time was ～1.5?min. Calibration sensitivity was measured to 1.3?mV/ppb. No interference was observed, when introducing at least 500 folds of interferences of gaseous species such as H₂O, HCl, H₂S, O₂, H₂, CO, CO₂, NO₂, SO₂, Cl₂, C₂H₂, CH₄ and volatile organic compounds (VOCs) to 250?ppb of O₃ solution. Reliability of the sensor was also evaluated via determination of O₃ in different air samples.