高分子有机场效应晶体管中退火引起的自组织微观结构变化的研究

为了进一步洞悉高分子薄膜自组织机理和高分子有机场效应晶体管(OFET)载流子迁移率之间的直接关联性,本工作采用先进的同步辐射掠入射X射线衍射(GIXRD)技术,研究了高分子OFET中高分子半导体高度区域规则的聚(3-己基噻吩)(RR-P3HT)工作层薄膜,由不同退火温度所导致的薄膜自组织微观结构的变化.GIXRD测试实验结果显示了,对于不同高分子薄膜制备方法(旋涂法及滴膜法)及不同溶液浓度(RR-P3HT溶液浓度为2.5 mg/ml及3.5 mg/ml)制备的RR-P3HT有机半导体工作层,在氮气气氛下, 关键词： 高分子有机场效应晶体管 同步辐射掠入射X射线衍射 自组织 退火     

高分子有机场效应晶体管中半导体薄膜结晶行为及微观结构变化的研究

为了探索高分子有机场效应晶体管(OFET)中高分子自组织机理与电荷传输的关联性,采用同步辐射掠入射X射线衍射技术研究了高分子OFET中以高度区域规则的聚(3-己基噻吩)(RR-P3HT)为代表的半导体层的结晶行为及微观结构组织变化,及其引起的高分子半导体电荷传输机理.研究发现,采用自组装单分子层(SAMs)技术进行界面修饰,可以完善绝缘层与RR-P3HT半导体层之间的界面效果.SAMs的形成改善了界面,可以有效地控制上层RR-P3HT半导体层的结晶性及微观结构,使较多的噻吩环面垂直于衬底、得到π-π堆积方向平行于衬底的二维微晶粒薄片结构,这种微观结构有效地形成了二维共轭电荷传输通道,完善了在RR-P3HT工作层生长过程中的自组织机理;并且对于RR-P3HT半导体工作层来说,慢速生长过程比快速生长过程更有利于有效的二维共轭微晶粒薄片生长,更能完善RR-P3HT工作层生长过程中的自组织机理. 关键词： 高度区域规则的聚(3-己基噻吩)有机场效应晶体管 同步辐射掠入射X射线衍射 自组织机理 微观结构     

旋涂速度对制备P3HT有机场效应晶体管性能的影响（英文）

采用溶液化的方法制备了以PMMA为绝缘层、P3HT为有源层的有机场效应晶体管。研究了P3HT有源层和PMMA绝缘层的旋涂速度对器件性能的影响。实验结果表明,当P3HT和PMMA的旋涂速度均为2 000 r/min时,器件的性能最佳。峰值场效应迁移率为6.84×10-2cm2·V-1·s-1。结果表明,选择适当的旋涂速度是一种有效提高溶液化制备有机场效应晶体管性能的方法。     

基于聚噻吩/聚己内酯共混物的有机薄膜晶体管

选择聚3-己基噻吩(P3HT)/聚己内酯(PCL)双晶共混体系制备了不同配比的共混物有机薄膜晶体管。电学性能研究发现,随着共混物中P3HT含量降低,薄膜晶体管的场效应迁移率、开关电流比和阈值电压等性能缓慢降低。当P3HT质量分数为40%时,共混物薄膜仍具有较好的场效应性能,迁移率为0.008 cm²·V^-1·s^-1,开关电流比为5×10³,阈值电压为45.5 V。原子力显微镜测试结果表明:共混物成膜时发生明显的垂直相分离,在界面处形成连续的半导体层,有利于载流子传输。     

旋涂速度对制备P3HT有机场效应晶体管性能的影响

采用溶液化的方法制备了以PMMA为绝缘层、P3HT为有源层的有机场效应晶体管.研究了P3HT有源层和PMMA绝缘层的旋涂速度对器件性能的影响.实验结果表明,当P3HT和PMMA的旋涂速度均为2 000 r/min时,器件的性能最佳.峰值场效应迁移率为6.84×10^-2 cm²·V^－1·s^－1.结果表明,选择适当的旋涂速度是一种有效提高溶液化制备有机场效应晶体管性能的方法.     

低工作电压聚噻吩薄膜晶体管

以高掺杂Si单晶片作为衬底且充当栅电极,采用磁控溅射法在硅片上沉积HfTiO薄膜作为栅介质层,聚三己基噻吩(P3HT)薄膜作为半导体活性层,金属Au作为源、漏电极,并采用十八烷基三氯硅烷(OTS)对栅介质层表面修饰,在空气环境下成功地制备出聚合物薄膜晶体管(PTFT).PTFT器件测试结果表明,该晶体管在低的驱动电压(<-1 V)下仍呈现出良好的饱和行为,其阈值电压和有效场效应迁移率分别为0.4 V和2.2×10^-2 cm²/V ·s.通过对金属-聚合物-氧化物 关键词： 聚合物薄膜晶体管 聚三己基噻吩 场效应迁移率 k栅介质')" href="#">高k栅介质     

基于蛋清栅绝缘层的高性能C_(60)有机场效应晶体管(英文)

采用生物材料(蛋清)作为栅绝缘层制备了基于C60为有源层的有机场效应晶体管。器件展现出了合理的电学特性,场效应迁移率和阈值电压分别为2.59 cm2·V-1·s-1和1.25 V。有机场效应晶体管展现良好性能的原因是蛋清具有较高的介电常数及热退火后形成的光滑表面形貌。实验结果表明,对于制备有机场效应晶体管来说,蛋清是一种有前途的绝缘层材料。     

PVA栅绝缘层浓度对P3HT有机场效应晶体管性能的影响

采用溶液制备法制备了用PVA作为绝缘层、P3HT作为有源层的有机场效应晶体管,,研究了不同浓度PVA栅绝缘层对器件性能的影响。实验结果显示,以质量分数为8%的PVA溶液制备的栅绝缘层具有最好的性能,器件的场效应迁移率为0.31 cm²·V^-1·s^-1,阈值电压为-6 V。进一步分析了PVA栅绝缘层浓度对器件性能提高的原因,结果表明,对于制备溶液化的有机场效应晶体管,选取合适的PVA栅绝缘层浓度非常重要。     

具有叠层超薄膜结构的高性能有机晶体管氨气传感器

研究了基于给-受体共轭聚合物双(2-氧代二氢吲哚-3-亚基)-苯并二呋喃-二酮和联噻吩(PBIBDF-BT)超薄膜叠层晶体管的电学性能及氨气传感特性。使用相分离方法以及转移-刻蚀步骤制备了不同堆叠层数的PBIBDF-BT超薄膜。系统地研究了PBIBDF-BT超薄膜堆叠层数与器件性能的关系。实验结果表明,单层PBIBDF-BT超薄膜器件对氨气具有良好的传感性能,电学性能较差。超薄膜叠层能够有效提高传感器的电学性能,随着超薄膜叠层数量的增加,器件迁移率不断上升;超薄膜层数增加为3层及更多时迁移率上升趋势变缓,迁移率最大值为0.58 cm~2·V~(-1)·s~(-1)。超薄膜叠层器件氨气传感性能在层数为2层后呈现下降趋势。通过PBIBDF-BT超薄膜叠层方法,制备出在1.0×10~(-5)氨气环境下,迁移率为0.23 cm~2·V~(-1)·s~(-1)、源漏电流变化百分比为90.7%、性能良好的OFET氨气传感器。     

有机场效应晶体管的非线性注入模型

有机场效应晶体管(Organic field effect transistor,OFET)的非线性特性是指其输出特性曲线在较低的漏极电压下出现类似于二极管的电压电流特性曲线,这种现象在有机场效应晶体管的实验研究中极为常见。Simonetti等通过引入随栅极电压变化的迁移率提出了模型并成功解释了这一现象,但实验中从器件转移特性得出的迁移率通常与栅极电压无关。本文通过引入常数迁移率对该模型进行改进,运用改进的模型研究了影响OFET非线性特性的主要因素,并对如何更加准确地获得器件参数进行了探究。     

Effects of concentration and annealing on the performance of regioregular poly（3-hexylthiophene） field-effect transistors

This paper investigates the effects of concentration on the crystalline structure, the morphology, and the charge carrier mobility of regioregular poly(3-hexylthiophene) (RR-P3HT) field-effect transistors (FETs). The RR-P3HT FETs with RR-P3HT as an active layer with different concentrations of RR-P3HT solution from 0.5~wt% to 2~wt% are prepared. The results indicate that the performance of RR-P3HT FETs improves drastically with the increase of RR-P3HT weight percentages in chloroform solution due to the formation of more microcrystalline lamellae and bigger nanoscale islands. It finds that the field-effect mobility of RR-P3HT FET with 2~wt% can reach 5.78× 10^-3~cm²/Vs which is higher by a factor of 13 than that with 0.5~wt%. Further, an appropriate thermal annealing is adopted to improve the performance of RR-P3HT FETs. The field-effect mobility of RR-P3HT FETs increases drastically to 0.09~cm²/Vs by thermal annealing at 150~℃, and the value of on/off current ratio can reach 10^4.     

Vacuum relaxation and annealing-induced enhancement of mobility of regioregular poly（3-hexylthiophene） field-effect transistors

In order to enhance the performance of regioregular poly(3-hexylthiophene) (RR-P3HT) field-effect transistors (FETs), RR-P3HT FETs are prepared by the spin-coating method followed by vacuum placement and annealing. This paper reports that the crystal structure, the molecule interconnection, the surface morphology, and the charge carrier mobility of RR-P3HT films are affected by vacuum relaxation and annealing. The results reveal that the field-effect mobility of RR-P3HT FETs can reach 4.17×10^ - 2~m²/(V.s) by vacuum relaxation at room temperature due to an enhanced local self-organization. Furthermore, it reports that an appropriate annealing temperature can facilitate the crystal structure, the orientation and the interconnection of polymer molecules. These results show that the field-effect mobility of device annealed at 150~℃ for 10 minutes in vacuum at atmosphere and followed by placement for 20 hours in vacuum at room temperature is enhanced dramatically to 9.00×10^ - 2 ~cm²/(V.s).     

Thickness dependence of surface morphology and charge carrier mobility in organic field-effect transistors

With the aim of understanding the relationships between organic small molecule field-effect transistors (FETs) and organic conjugated polymer FETs, we investigate the thickness dependence of surface morphology and charge carrier mobility in pentacene and regioregular poly (3-hexylthiophene) (RR-P3HT) field-effect transistors. On the basis of the results of surface morphologies and electrical properties, we presume that the charge carrier mobility is largely related to the morphology of the organic active layer. We observe that the change trends of the surface morphologies (average size and average roughness) of pentacene and RR-P3HT thin films are mutually opposite, as the thickness of the organic layer increases. Further, we demonstrate that the change trends of the field-effect mobilities of pentacene and RR-P3HT FETs are also opposite to each other, as the thickness of the organic layer increases within its limit.     

Enhanced charge carrier injection in heterojunction organic field-effect transistor by inserting an MoO3 buffer layer

A top-contact organic field-effect transistor(OFET) is fabricated by adopting a pentacene/1,1’-bis(di-4tolylaminophenyl) cyclohexane(TAPC) heterojunction structure and inserting an MoO3 buffer layer between the TAPC organic semiconductor layer and the source/drain electrode.The performances of the heterojunction OFET,including output current,field-effect mobility,and threshed voltage,are all significantly improved by introducing the MoO3 thin buffer layer.The performance improvement of the modified heterojunction OFET is attributed to a better contact formed at the Au/TAPC interface due to the MoO3 thin buffer layer,thereby leading to a remarkable reduction of the contact resistance at the metal/organic interface.     

A high mobility C60 field-effect transistor with an ultrathin pentacene passivation layer and bathophenanthroline/metal bilayer electrodes

C₆₀ field-effect transistor (OFET) with a mobility as high as 5.17 cm²/V·s is fabricated. In our experiment, an ultrathin pentacene passivation layer on poly-(methyl methacrylate) (PMMA) insulator and a bathophenanthroline (Bphen)/Ag bilayer electrode are prepared. The OFET shows a significant enhancement of electron mobility compared with the corresponding device with a single PMMA insultor and an Ag electrode. By analysing the C₆₀ film with atomic force microscopy and X-ray diffraction techniques, it is shown that the pentacene passivation layer can contribute to C₆₀ film growth with the large grain size and significantly improve crystallinity. Moreover, the Bphen buffer layer can reduce the electron contact barrier from Ag electrodes to C₆₀ film efficiently.     

Field-effect transistor structures on the basis of poly(3-hexylthiophene), fullerene derivatives [60]PCBM, [70]PCBM,and nickel nanoparticles

Organic field-effect transistor (OFET) structures with the active layers on the basis of composite films of semiconductor polymer poly(3-hexylthiophene) (P3HT), fullerene derivatives [60]PCBM, [70]PCBM, and nickel (Ni) nanoparticles are obtained, and their optical, electrical, and photoelectrical properties are studied. It is shown that introducing Ni nanoparticles into P3HT: [60]PCBM and P3HT: [70]PCBM films leads to an increase in the absorption and to quenching of photoluminescence of the composite in the 400–600 nm spectral band due to the plasmon effect. In P3HT: [60]PCBM: Ni and P3HT: [70]PCBM: Ni OFET structures at the P3HT: [60]PCBM and P3HT: [70]PCBM concentrations of ~1: 1 and Ni concentrations of ~3–5 wt %, current–voltage (I–V) characteristics typical of ambipolar OFETs with the dominant hole conduction are observed. The charge-carrier (hole) mobilities calculated from the I–V characteristic at V_G =–10 V were found to be ~0.46 cm²/(V s) for P3HT: [60]PCBM: Ni and ~4.7 cm²/(V s) for P3HT: [70]PCBM: Ni, which means that the mobility increases if [60]PCBM in the composition is replaced with [70]PCBM. The effect of light on the I–V characteristics of P3HT: [60]PCBM: Ni and P3HT: [70]PCBM: Ni OFETs is studied.     

Laser printing and characterization of semiconducting polymers for organic electronics

Hybrid organic/inorganic thin-film transistors (TFTs) with bottom-contact configuration were fabricated using the Laser Induced Forward Transfer (LIFT) process. The semiconducting polymer P3HT was laser printed from a donor to a receiver substrate in order to form the active layer of the TFTs. With a single laser pulse, P3HT pixels were successfully printed. The printed material was analyzed morphologically by means of Optical Microscopy and its thickness was measured by profilometry. In addition, structural characterization of P3HT thin films before and after laser printing took place by using UV-Visible absorption spectroscopy and X-Ray Diffraction. It was found that the crystallinity of the investigated films is improved upon annealing. An organic thin-film transistor (OTFT) with laser printed P3HT pixel as a channel layer was then fabricated. The OTFTs indicated a field-effect mobility up to 2.23?10^?4 cm²/Vs and an on/off ratio on the order of 10–100.     

A new method to invert top-gate organic field-effect transistors for Kelvin probe investigations

In this contribution, we present a technique which allows for the investigation of the local channel potentials of a poly(3-hexylthiophene) (P3HT)-based top-gate field-effect transistor. Usually it is impossible to measure the channel potentials of a top-gate transistor with a Kelvin probe force microscope (KPFM) due to the electrical shielding of the top-gate or the weak capacitive coupling of the tip through the thick substrate to the channel. However, by depositing the entire device on a water solvable polyvinyl alcohol layer, devices can be completely detached from the substrate, creating a free-standing functioning organic field-effect transistor (OFET). After detaching, it is possible to laminate the inverted device on another substrate. This method grants access to the usually hidden channel of the top-gate OFET, and therefore KPFM measurements can be performed.