In this paper, the dynamics of bias stress phenomenon in Sexithiophene (T6) Field Effect Transistors (FETs) has been investigated. T6 FETs have been fabricated by vacuum depositing films with thickness from 10 nm to 130 nm on Si/SiO2 substrates. After the T6 film structural analysis by X-Ray diffraction and the FET electrical investigation focused on carrier mobility evaluation, bias stress instability parameters have been estimated and discussed in the context of existing models. By increasing the film thickness, a clear correlation between the stress parameters and the structural properties of the organic layer has been highlighted. Conversely, the mobility values result almost thickness independent.
Organic small molecule field-effect transistors with Cytop(TM) gate dielectric: eliminating gate bias stress effects
我们报告的有机场效应晶体管与前所未有的电阻对栅极偏置应力。单晶和薄膜晶体管采用有机栅极电介质CytopTM。该含氟聚合物具有高度防水性，并显示出显著的电击穿强度。单晶晶体管始终具有非常高的电气质量：接近零起始，非常陡峭的亚阈值摆幅（平均值：1.3 nF V/（dec cm 2））和可忽略的电流滞后。此外，扩展的栅极偏置应力仅导致传输特性的边际变化。与氢化非晶硅相比，有机半导体的稳定性似乎没有概念上的限制。
Single crystal field-effect transistors based on an organic selenium-containing semiconductor
我们报道了基于二苯基苯并二硒（DPh-BDSe）的单晶场效应晶体管（FET）的制备和表征。这些有机场效应晶体管（OFFET）用作p沟道累积模式器件。在室温下，对于最好的器件，阈值电压小于-7V，并且载流子迁移率几乎与栅极偏压无关，范围从1 cm 2/Vs到1.5 cm 2/Vs，取决于源漏偏压。通过冷却到室温以下，迁移率略有增加，并且在280 K以下降低。
As high-performance organic semiconductors, π-conjugated polymers have attracted much attention due to their charming advantages including low-cost, solution processability, mechanical flexibility, and tunable optoelectronic properties. During the past several decades, the great advances have been made in polymers-based OFETs with p-type, n-type or even ambipolar characterics. Through chemical modification and alignment optimization, lots of conjugated polymers exhibited superior mobilities, and some mobilities are even larger than 10 cm2 V-1 s-1 in OFETs, which makes them very promising for t…
Two-dimensional Quasi-Freestanding Molecular Crystals for High-Performance Organic Field-Effect Transistors
二维原子晶体由于其令人兴奋的物理和器件应用，近年来得到了广泛的研究。然而，具有可扩展加工性和竞争性器件性能的分子对应物仍然具有挑战性。在这里，我们证明了高质量的少层二辛基苯并噻吩并苯并噻吩分子晶体可以通过范德华外延生长在石墨烯或氮化硼衬底上，具有精确控制的厚度下降到单层，大面积单晶，低工艺温度和图案化能力。晶体层是原子级光滑的，并且由于弱的范德华相互作用而与衬底有效地解耦，从而为高性能有机晶体管提供原始界面。结果，氮化硼上的单层二辛基苯并噻吩并苯并噻吩分子晶体场效应晶体管显示出高达10 cm ~ 2 V ~（-1）s ~（-1）的创纪录的高载流子迁移率和在1V左右的积极缩放的饱和电压。我们的工作揭示了一类令人兴奋的新的二维分子材料的电子和光电应用。
Solution processed polymers are at the core of organic electronics. Polyradicals (polymers in which each repeating unit contains an unpaired spin) are unique alternatives to their p-conjugated, semiconducting counterparts. Unique of polyradicals are tunable charge states localized at their repeating units, which enable electrically switchable charge transport regimes. Tremendous efforts were focused on polyradical memristors and batteries. Notwithstanding recent progress in doping, polyradical field-effect transistors (PR-FETs) have not been reported. Here, we show that vertical architectures,…
An Improved Process for Fabricating High-Mobility Organic Molecular Crystal Field-Effect Transistors
在本文中，我们提出了一种改进的方法，用于生产弹性体晶体管邮票和高迁移率的有机场效应晶体管（FET）的半导体并苯分子晶体的基础上。特别地，我们已经消除了使用硅烷化的Si晶片来固化印模以及处理易碎的微米厚度的聚二甲基硅氧烷（PDMS）绝缘膜并将其无气泡地层压在PDMS晶体管印模上的需要。我们发现，尽管改变了设计，更粗糙的PDMS表面，以及在空气中对器件进行层压和测量，我们仍然实现了10 cm^2/Vs量级的电迁移率，与有机FET的当前技术水平相当。我们的器件显示空穴导电，阈值电压为-9V，对应的陷阱密度为1.4 x 10^10 cm^-2。
Organic printed electronics has proven its potential as an essential enabler for applications related to healthcare, entertainment, energy and distributed intelligent objects. The possibility of exploiting solution-based and direct-writing production schemes further boosts the benefits offered by such technology, facilitating the implementation of cheap, conformable, bio-compatible electronic applications. The result shown in this work challenges the widespread assumption that such class of electronic devices is relegated to low-frequency operation, owing to the limited charge mobility of the …
The organic electrochemical transistor (OECT) with a conjugated polymer as the active material is the elementary unit of organic bioelectronic devices. Increased functionalities, such as low power consumption, can be achieved by building complementary circuits featuring two or more OECTs. Complementary circuits commonly combine both p- and n-type transistors to reduce power draw. While p-type OECTs are readily available, n-type OECTs are less common mainly due to poor stability of the n-type active channel material in aqueous electrolyte. Additionally, an OECT based complementary circuit requi…
We investigate domain formation and local morphology of thin films of $α$-sexithiophene ($α$-6T) on Au(100) beyond monolayer coverage by combining high resolution scanning tunneling microscopy (STM) experiments with electronic structure theory calculations and computational structure search. We report a layerwise growth of highly-ordered enantiopure domains. For the second and third layer, we show that the molecular orbitals of individual $α$-6T molecules can be well resolved by STM, providing access to detailed information on the molecular orientation. We find that already in the second layer…
Thin-film transistors (TFTs) represent a wide-spread tool to determine the charge-carrier mobility of materials. Mobilities and further transistor parameters like contact resistances are commonly extracted from the electrical characteristics. However, the trust in such extracted parameters is limited, because their values depend on the extraction technique and on the underlying transistor model. We propose a technique to establish whether a chosen model is adequate to represent the transistor operation. This two-step technique analyzes the electrical measurements of a series of TFTs with diffe…
Existing flexible electronics are planar, nonbreathable, and easily damaged. In this work, authors introduce a new paradigm of free-form three-dimensional integrated circuits assembled on a single textile thread for ultimate flexibility. Transistors are assembled as daisy chain on a thread and utilize deep eutectic solvent gels, or eutectogels as nonvolatile, breathable, and repairable dielectric for gating organic electrochemical transistor. The eutectogels provide stable transistor performance without the need for encapsulation, are air permeable to the skin, and make the Organic Eutectogel …
The first-principles simulation of the electronic structure of organic semiconductors in solution poses a number of challenges that are not trivial to address simultaneously. In this work, we investigate the effects and the mutual interplay of solvation, alkylization, and doping on the structural, electronic, and optical properties of sexithiophene, a representative organic semiconductor molecule. To this end, we employ (time-dependent) density functional theory in conjunction with the polarizable-continuum model. We find that the torsion between adjacent monomer units plays a key role, as it …
Organic electrochemical transistors (OECTs) are currently being investigated for various applications, ranging from sensors to logics and neuromorphic hardware. The fabrication process must be compatible with flexible and scalable digital techniques to address this wide spectrum of applications. Here, we report a direct-write additive process to fabricate fully 3D printed OECTs. We developed 3D printable conducting, semiconducting, insulating, and electrolyte inks to achieve this. The 3D-printed OECTs, operating in the depletion mode, can be fabricated on thin and flexible substrates, yielding…
Organic Electrochemical Transistors are considered today as a key technology to interact with biological medium through their intrinsic ionic-electronic coupling. In this paper, we show how this coupling can be finely tuned (in operando) post-microfabrication via electropolymerization technique. This strategy exploits the concept of adaptive sensing where both transconductance and impedance are tunable and can be modified on-demand to match different sensing requirements. Material investigation through Raman spectroscopy, atomic force microscopy and scanning electron microscopy reveals that el…
