溶液法大面积制备有机小分子场效应晶体管

作为柔性电子器件的基本构筑元件,有机场效应晶体管(OFETs)近年来受到深入研究并在高性能材料研发和器件多功能应用等方面取得了长足的进展。溶液加工技术以其温和的操作条件和灵活多样的工艺流程,成为实现高性能有机场效应晶体管器件低成本、大面积制备的优良选择。与聚合物相比,小分子有机半导体材料具有较高的固态堆积有序度及紧密程度和材料纯度,更易加工出性能优良的器件。然而小分子材料的成膜性较差,溶液加工潜能欠佳。如何通过不同的溶液加工技术制备取向均一的大面积连续小分子半导体薄膜,进而构筑高性能大面积器件阵列,成为了领域内的研究重点。本文概述了近年来可溶液加工且性能优良的小分子有机半导体材料研究进展,并依据工艺特点,分别介绍了溶液滴注、弯液面引导涂布和打印这三类可实现大面积制备的溶液加工技术,最后对溶液法大面积制备有机小分子场效应晶体管领域的发展前景进行了展望。     

马兰戈尼效应在有机半导体成膜中的应用

<正>1背景介绍以有机发光二极管、有机太阳能电池和有机场效应晶体管为主的有机半导体薄膜器件,因在便携、可穿戴电子器件领域有巨大的应用前景,而逐渐成为无机半导体器件的一个重要补充。溶液法生长有机半导体薄膜工艺更使有机半导体器件的低成本、可在柔性基底上大面积制备的优点得到体现,因而受到广泛关注。但是,溶液法制备工艺也存在着诸多不足,比如被称为"咖啡环"效应的溶剂自然挥发造成的薄     

有机场效应晶体管中给体-受体共聚物材料研究进展

自20世纪80年代至今,有机场效应晶体管(Organic field-effect transistor,OFET)的研究已经取得了很大的发展,目前可用于场效应晶体管的有机半导体材料已达数百种.经过30年的发展,有机场效应晶体管的迁移率从10-6~10-5cm2?V-1?s-1提高到12 cm2?V-1?s-1,增长了6个数量级,其性能已经超过了无定形性硅场效应晶体管(0.1~1 cm2?V-1?s-1).值得指出的是,目前该类高性能的材料几乎都是基于给体-受体(Donor-Acceptor,简称D-A)的共轭聚合物,它也被誉为第三代半导体材料.本文综述了近年来国内外D-A共聚物半导体材料的研究状况,对空穴传输型、双极传输型和电子传输型的D-A共聚物半导体材料进行了分类总结和评述,并对其设计思路,器件制备及性能做了详细介绍,总结了材料的化学结构与器件性能间的基本规律,为今后应用于有机场效应晶体管的给体-受体共聚物半导体材料提供设计思路.     

烷基链长度对非对称含噻吩五元稠环化合物传输性能的影响北大核心CSCD

含噻吩并苯类分子是一类代表性的高迁移率有机半导体材料,以其为共轭骨架构建的不对称分子在薄膜中倾向于形成双层排列结构,并以二维层状方式生长,有利于实现高迁移率。烷基取代基的长度会对有机半导体材料的堆积形貌产生影响。本文设计合成了不同长度烷基链取代的噻吩并[4,5-b][1]苯并噻吩并[3,2-b][1]苯并噻吩(syn-BTBTT-Cn,n=4,5,6,7,8,10),系统研究了烷基链长度对化合物热稳定性、能级、载流子传输能力、堆积结构和薄膜形貌等方面的影响。结果表明,所有化合物均不具备液晶性,热稳定性良好。在所制备的蒸镀薄膜中所有分子均形成双层堆积结构,共轭核在层内形成鱼骨架堆积,烷基链长度会影响薄膜的有序度和堆积的紧密程度。基于该类材料制备的有机薄膜晶体管(OTFT)器件的迁移率都超过7.0 cm^(2)/(V·s),其中syn-BTBTT-C8分子的迁移率最高可达13.8 cm^(2)/(V·s),平均值为12.5 cm^(2)/(V·s)。     

疏水基底表面可控生长有机单晶阵列用于高性能晶体管

有机场效应晶体管(OFETs)、有机发光二极管等光电器件有望实现低成本柔性光电子应用,但低成本潜力取决于基于溶液法大面积沉积有机半导体单晶(OSSC)阵列的能力.然而,差的表面润湿行为和复杂的流体动力学过程限制了溶液沉积大面积OSSC阵列.本文中,我们通过添加微量的表面活性剂改善了润湿性能和流体干燥动力学,并增强了有机...     

基于表面等离子共振效应的有机光敏晶体管

通过原位制备金纳米颗粒,利用表面等离子共振效应,在金纳米颗粒表面旋涂无可见光响应的聚合物获得了同时具有高迁移率(0.12 cm2·V-1·s-1)和高响应度(11.6 A/W)的有机光敏晶体管.金纳米颗粒表面的化学修饰对提高器件性能起到关键作用.基于表面等离子共振效应建立了一种利用无可见光响应(或弱可见光响应)有机半导体获得高性能有机光敏晶体管的方法.     

基于有机双层的双极性有机场效应晶体管研究进展

由双极性有机场效应晶体管(OFETs)制备的有机互补电路具有操作电压低、能耗低和成本低等优点,在有机互补电路方面有很大的应用前景,引起了科学家们极大的研究兴趣.同时具有高且匹配的空穴迁移率和电子迁移率的双极性有机半导体分子是制备高性能有机互补电路的必要条件之一,然而迄今为止该类双极性有机半导体分子的报道比较少,大部分双...     

蒽及其衍生物在有机场效应晶体管中的应用

近年来,有机场效应晶体管因其低成本、可低温制备、与柔性衬底兼容,以及能够大面积制备等优势而备受关注,其性能也在不断提高。其中并苯类化合物作为一类非常重要的有机半导体材料得到了广泛的关注和研究。渡越时间法测试表明蒽的迁移率能够达到3.0 cm²V^-1s^-1,应该具有较好的场效应晶体管应用。人们对蒽及其衍生物进行了一系列的研究,取得了很大的成功。这里,我们对蒽及其衍生物在有机场效应晶体管中的应用做一个较为全面的综述,期望为国内外同行提供一定的参考。     

小分子场效应晶体管

近几年来,作为新一代半导体晶体管的有机场效应晶体管(OFET)在制备技术和器件性能上都取得了很大的进步,并引起了有机半导体领域研究人员的广泛关注。本文主要介绍了常见的小分子材料在场效应晶体管中的应用,并对几种有机小分子材料的结构和场效应性能做了总结。     

有机场效应晶体管和分子电子学研究进展

近几年来,有机场效应晶体管在材料和器件方面都取得了长足的进展,成为分子电子学的一个重要方向。本文从有机半导体材料设计、有机半导体器件的构筑、单分子电子器件和纳米管在电子器件中的应用等方面,简单综述了有机场效应晶体管和分子电子学的最新研究进展。     

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.     

Adsorption and activity of Thermomyces lanuginosus lipase on hydrophobic and hydrophilic surfaces measured with dual polarization interferometry (DPI) and confocal microscopy

The adsorption and activity of Thermomyces lanuginosus lipase (TLL) was measured with dual polarization interferometry (DPI) and confocal microscopy at a hydrophilic and hydrophobic surface. In the adsorption isotherms, it was evident that TLL both had higher affinity for the hydrophobic surface and adsorbed to a higher adsorbed amount (1.90 mg/m²) compared to the hydrophilic surface (1.40–1.50 mg/m²). The thickness of the adsorbed layer was constant (3.5 nm) on both surfaces at an adsorbed amount >1.0 mg/m², but decreased on the hydrophilic surface at lower surface coverage, which might be explained by partially unfolding of the TLL structure. However, a linear dependence of the refractive index of the adsorbed layer on adsorbed amount of TLL on C18 surfaces indicated that the structure of TLL was similar at low and high surface coverage. The activity of adsorbed TLL was measured towards carboxyfluorescein diacetate (CFDA) in solution, which upon lipase activity formed a fluorescent product. The surface fluorescence intensity increase was measured in a confocal microscope as a function of time after lipase adsorption. It was evident that TLL was more active on the hydrophilic surface, which suggested that a larger fraction of adsorbed TLL molecules were oriented with the active site facing the solution compared to the hydrophobic surface. Moreover, most of the activity remained when the TLL surface coverage decreased. Earlier reports on TLL surface mobility on the same surfaces have found that the lateral diffusion was highest on hydrophilic surfaces and at low surface coverage of TLL. Hence, a high lateral mobility might lead to a longer exposure time of the active site towards solution, thereby increasing the activity against a water-soluble substrate.     

Controlling coffee ring structure on hydrophobic polymer surface by manipulating wettability with O2 plasma

A simple and novel method is firstly reported for controlling coffee ring structure on polystyrene (PS) film surface by O₂ plasma. O₂ plasma treatment leads to the wettability change of PS surface from hydrophobic to hydrophilic. For hydrophilic PS surface the coffee ring structure is avoided relying on the motion of contact line (CL) while SiO₂ microspheres are left. The motion of the CL is produced based on the viscosity and Marangoni effect with the addition of polymer additives. For hydrophobic PS surface coffee ring structure still persists even with polymer additives because SiO₂ microspheres transfer with the motion of the CL at the beginning of droplet evaporation and accumulate at the droplet edge at late stage with the pinning of the CL. As a result, uniform and macroscale SiO₂ microspheres deposition without coffee ring structure and SiO₂ microspheres deposition with coffee ring structure are controlled by O₂ plasma. This method provides a new way to tune coffee ring structure with smart surface and may be potentially useful for a range of application at material deposition and diagnosing diseases.     

High performance organic transistors and phototransistors based on diketopyrrolopyrrole-quaterthiophene copolymer thin films fabricated via low-concentration solution processing

Herein, highly crystalline diketopyrrolopyrrole-quaterthiophene copolymer thin films were achieved by a simple low-concentration solution processing with a little material waste, which exhibit efficient charge transport and optoelectronic properties for constructing high performance OFET and phototransistors.     

Photoresponsive n-channel organic field-effect transistors based on a tri-component active layer

Photoresponsive OFETs were fabricated based on a tri-component active layer (NDI2OD-DTYM2, spiropyran and polystyrene). The results demonstrated that these OFETs displayed photoresponsive feature to alternate UV and vis light due to the photoisomerization of spiropyran between the closed-ring state and ionic open-ring state.     

Air-stable n-type organic field-effect transistors based on solution-processable, electronegative oligomers containing dicyanomethylene-substituted cyclopenta[b]thiophene

Solution-processable, electronegative, π-conjugated systems containing dicyanomethylene-substituted cyclopenta[b]thiophene were synthesized as potential active materials for air-stable n-type organic field-effect transistors (OFETs). Electrochemical measurements revealed that these compounds exhibited electrochemical stability and that the lowest unoccupied molecular orbital (LUMO) had an energy level less than -4.0 eV. Flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements were performed, and the value of intradomain electron mobility was determined to be as high as 0.1 cm(2) V(-1) s(-1) . The OFETs were fabricated by spin-coating thin films of the compounds as an active layer. The electron mobility of the OFETs was 3.5×10(-3) cm(2) V(-1) s(-1) in vacuum. Furthermore, electron mobility of the same order of magnitude and stable characteristics were obtained under air-exposed conditions. X-ray diffraction measurements of the spin-coated thin films revealed the difference of molecular arrangements depending on the inner conjugated units. Atomic force microscopy measurements of crystalline-structured films exhibited the formation of grains. The accomplishment of air-stability was attributed to the combined effect of the low-lying LUMO energy level and the molecular arrangements in the solid state, avoiding both the quenching of electron carriers and the intrusion of oxygen and/or moisture.     

蓝宝石衬底上化学气相沉积法生长石墨烯

化学气相沉积(CVD)法是制备大面积、高质量石墨烯材料的主要方法之一,但存在衬底转移和碳固溶等问题,本文选用蓝宝石衬底弥补了传统CVD法的不足。利用CVD法在蓝宝石衬底上生长石墨烯材料,研究生长温度对石墨烯表面形貌和晶体质量的影响。原子力显微镜(AFM)、光学显微镜(OM)、拉曼光谱和霍尔测试表明,低温生长有利于保持材料表面的平整度,高温生长有利于提高材料的晶体质量。研究氢气和碳源对蓝宝石衬底表面刻蚀作用机理,发现氢气对蓝宝石衬底有刻蚀作用,而单纯的碳源不能对衬底产生刻蚀效果。在1200 ℃下,直径为50 mm的晶圆级衬底上获得平整度和质量相对较好的石墨烯材料,室温下载流子迁移超过1000 cm²·V^-1·s^-1。     

Grafting of poly(ethylene oxide) to the surface of polyaniline films through a chlorosulfonation method and the biocompatibility of the modified films

Poly(ethylene oxide) (PEO) could be grafted on the surface of polyaniline (PANI) films by chlorosulfonating the films with chlorosulfonic acid followed by reacting the modified films with PEO in a pyridine solution. The modified PANI films were examined by X-ray photoelectron spectroscopy and water droplet contact angles. The surface of the PEO grafted to hydrophobic PANI films became hydrophilic and the amounts of bovine serum albumin and human blood plasma platelet adsorbed onto it were decreased by more than 80%. For comparison purposes, and because the water wetting angle can be used as a measure of biocompatibility, wetting angle experiments have been also carried out for Pluronic triblock copolymer grafted to PANI and PEO or Pluronic molecules entrapped on the surfaces of PANI films. PANI was selected as substrate because one can easily change its surface properties by PEO grafting and because being conductive can be used as a sensor.     

Effect of the phase states of self-assembled monolayers on pentacene growth and thin-film transistor characteristics

To investigate the effects of the phase state (ordered or disordered) of self-assembled monolayers (SAMs) on the growth mode of pentacene films and the performance of organic thin-film transistors (OTFTs), we deposited pentacene molecules on SAMs of octadecyltrichlorosilane (ODTS) with different alkyl-chain orientations at various substrate temperatures (30, 60, and 90 degrees C). We found that the SAM phase state played an important role in both cases. Pentacene films grown on relatively highly ordered SAMs were found to have a higher crystallinity and a better interconnectivity between the pentacene domains, which directly serves to enhance the field-effect mobility, than those grown on disordered SAMs. Furthermore, the differences in crystallinity and field-effect mobility between pentacene films grown on ordered and disordered substrates increased with increasing substrate temperature. These results can be possibly explained by (1) a quasi-epitaxy growth of the pentacene film on the ordered ODTS monolayer and (2) the temperature-dependent alkyl chain mobility of the ODTS monolayers.     

Organic semiconductors for solution-processable field-effect transistors (OFETs)

The cost-effective production of flexible electronic components will profit considerably from the development of solution-processable, organic semiconductor materials. Particular attention is focused on soluble semiconductors for organic field-effect transistors (OFETs). The hitherto differentiation between "small molecules" and polymeric materials no longer plays a role, rather more the ability to process materials from solution to homogeneous semiconducting films with optimal electronic properties (high charge-carrier mobility, low threshold voltage, high on/off ratio) is pivotal. Key classes of materials for this purpose are soluble oligoacenes, soluble oligo- and polythiophenes and their respective copolymers, and oligo- and polytriarylamines. In this context, micro- or nanocrystalline materials have the general advantage of somewhat higher charge-carrier mobilities, which, however, could be offset in the case of amorphous, glassy materials by simpler and more reproducible processing.