Spontaneously formed high-performance charge-transport layers of organic single-crystal semiconductors on precisely synthesized insulating polymers

Makita, Tatsuyuki; Sasaki, Masayuki; Annaka, Tatsuro; Sasaki, Mari; Matsui, Hiroyuki; Mitsui, Chikahiko; Kumagai, Shohei; Watanabe, Shun; Hayakawa, Teruaki; Okamoto, Toshihiro

doi:10.1063/1.4981774

Cited by 16 publications

(11 citation statements)

References 30 publications

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“…The difference can be attributed to the existence of thin carrier injection layer, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquionodimethane (F 4 -TCNQ), which may also serve as a buffer layer for the subsequent metal deposition. The value of the subthreshold swing (S) estimated from the transistor characteristics was less than 100 mV decade −1 , which is much lower than that obtained for multilayers of DNBDT TFTs with the vacuum evaporated gold contacts 43 . Generally, S is associated with the density of deep traps located at the carrier transport interface or in the bulk of the semiconductor 44 .…”

Section: Resultsmentioning

confidence: 66%

Damage-free Metal Electrode Transfer to Monolayer Organic Single Crystalline Thin Films

Makita

Yamamura

Tsurumi

et al. 2020

Sci Rep

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Solution-processed organic thin film transistors (OTFTs) are an essential building block for nextgeneration printed electronic devices. Organic semiconductors (OSCs) that can spontaneously form a molecular assembly play a vital role in the fabrication of otfts. otft fabrication processes consist of sequential deposition of functional layers, which inherently brings significant difficulties in realizing ideal properties because underlayers are likely to be damaged by application of subsequent layers. These difficulties are particularly prominent when forming metal contact electrodes directly on an OSC surface, due to thermal damage during vacuum evaporation and the effect of solvents during subsequent photolithography. In this work, we demonstrate a simple and facile technique to transfer contact electrodes to ultrathin OSC films and form an ideal metal/OSC interface. Photolithographically defined metal electrodes are transferred and laminated using a polymeric bilayer thin film. One layer is a thick sacrificial polymer film that makes the overall film easier to handle and is water-soluble for dissolution later. The other is a thin buffer film that helps the template adhere to a substrate electrostatically. The present technique does not induce any fatal damage in the substrate OSC layers, which leads to successful fabrication of OTFTs composed of monolayer OSC films with a mobility of higher than 10 cm 2 V −1 s −1 , a subthreshold swing of less than 100 mV decade −1 , and a low contact resistance of 175 Ω⋅cm. The reproducibility of efficient contact fabrication was confirmed by the operation of a 10 × 10 array of monolayer OTFTs. The technique developed here constitutes a key step forward not only for practical OTFT fabrication but also potentially for all existing vertically stacked organic devices, such as light-emitting diodes and solar cells.

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Section: Resultsmentioning

confidence: 66%

Damage-free Metal Electrode Transfer to Monolayer Organic Single Crystalline Thin Films

Makita

Yamamura

Tsurumi

et al. 2020

Sci Rep

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“…Inspired by the potential improvements in terms of reproducibility and device‐to‐device uniformity that can result from the addition of polymer binders to small molecule semiconductor solutions, we also fabricated and analyzed films based on blends of C8‐BTBT with the insulating polymer polystyrene. In these blends, the molecular weight of the polymer constitutes a fundamental parameter for the effectiveness of the approach . In particular, differences with regard to the solution's film formation properties are anticipated as viscosity is expected to significantly change with the molecular weight.…”

Section: Resultsmentioning

confidence: 99%

High‐Mobility, Solution‐Processed Organic Field‐Effect Transistors from C8‐BTBT:Polystyrene Blends

Haase

Rocha

Hauenstein

et al. 2018

Adv Elect Materials

105

103

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record values exceeding 10 cm 2 V −1 s −1 have been reported. [3][4][5][6][7][8] Though these results are promising, some of these reported values suffer from overestimation, [9,10] require significant engineering efforts, [3] complex fabrication procedures, [4] or employ nonscalable fabrication techniques, [5] ultimately highlighting the need for alternative and potentially more industry-relevant processing methods. We believe that adjustments to existing solution coating methods rather than intensive technology engineering could result in a feasible and simple approach.Ink properties such as the solvents' boiling point, [11] solubility parameters, [12] or the solute concentration [13] can be tuned in order to control crystal growth and packing in a manner that provides favorable electrical characteristics. Such ink engineering has recently been shown to generate high mobility devices based on C8-BTBT. [14] In particular, a distinct increase of performance by utilizing a solvent mixture rather than a single solvent has been reported for a range of semiconductors, including TIPS-pentacene [15,16] or diketopyrrolopyrrole (DPP)-based polymers. [17] This approach has frequently been combined with another effective method -the addition of a polymer additive to the printing solution. This combination has been shown to significantly reduce the device-to-device variations and yielded improved transistor performances when applied to high-mobility small molecules, like TIPS-pentacene, [18] diF-TES-ADT, [8,19,20] or even C8-BTBT. [5,7,21,22] In this study, we explore various blends of the high-mobility semiconductor C8-BTBT with the inert polymer polystyrene (PS) with the objective of improving device-to-device uniformity and investigating the effect on device characteristics. We report improved film formation that results in the reduction of deviceto-device variations and the reliable fabrication of high-mobility organic field-effect transistors by a scalable, meniscus-guided coating method, and demonstrate OFETs based on C8-BTBT, that to the best of our knowledge show the highest intrinsic mobility so far reported. Results and Discussion Discussion of C8-BTBT-Based Devices in LiteratureIn the literature, the blending of C8-BTBT and PS led to improvements in the effective mobility of organic field-effect Organic field-effect transistors based on aligned small molecule semiconductors have shown high charge carrier mobilities in excess of 10 cm 2 V −1 s −1 . This makes them a viable alternative to amorphous inorganic semiconductors especially if a high reproducibility can be achieved. Here, the optimization of high mobility organic field-effect transistors based on the organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b] benzothiophene (C8-BTBT) via the addition of a polymer additive to the printing solution is reported. Specifically, films and devices are compared based on solutions of the neat semiconductor and the blend with polystyrene and shear-coated devices with excellent device characteristics and gate-voltage-ind...

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“…The deposition technique of organic semiconductors is critical for the semiconductor/dielectric interface trap density. Single‐crystalline organic semiconductors always provide the best device performance due to the absence of grain boundary, dangling bonds, or other structural defects . Willa et al compared the electrical properties of OFETs as a function of the semiconductor degree of the crystalline order .…”

Section: Low‐power‐consumption Ofetsmentioning

confidence: 99%

“…Organic field‐effect transistors (OFETs) have undergone tremendous development in the past decade . To date, OFETs not only outperform amorphous Si thin‐film transistors (TFTs) with field‐effect mobility exceeding 10 cm 2 V −1 s −1 and an operating on/off ratio larger than 10 8 , but also demonstrate excellent flexibility and solution processability . The large‐scale integration of OFETs has been applied for integrated circuits, sensor arrays, and data storage .…”

Section: Introductionmentioning

confidence: 99%

Organic Field‐Effect Transistor for Energy‐Related Applications: Low‐Power‐Consumption Devices, Near‐Infrared Phototransistors, and Organic Thermoelectric Devices

Ren

Yang

Gao

et al. 2018

Advanced Energy Materials

112

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The operating frequency of ring oscillators or radio-frequency identification tags made by OFETs have surpassed MHz. [27,28] With the growing level of integration and the operating frequency of OFETs, the power dissipation issue can no longer be ignored. Considering the material composition of most organic semiconductors, controlling the temperature rise within a reasonable range is important to avoid the unwanted degradation of organic materials and therefore maintain stable device operation. In addition, OFETs fabricated on flexi ble substrates somehow limit the use of conventional batteries. To avoid externally wiring the batteries, flexible OFET-based circuits can be expected to be self-powered by integrating them with organic solar cells, thermoelectric modules, or triboelectric nanogenerators. [29,30] All of these demands require OFETs operating with extremely low power consumption. Rapid progress has been made in this field, and research efforts have focused on reducing the operating voltage of OFETs, [31][32][33] enhancing the switching efficiency of transistors, [34][35][36][37] and demonstrating several novel device concepts for low-power applications. [38][39][40][41][42] Despite the switching function, OFETs can also be utilized in emerging energy-related applications, such as near-infrared (NIR) photodetectors and organic thermoelectric devices dueThe organic field-effect transistor (OFET) is the basic building block of integrated circuits. The charge carrier mobility and operating frequency of OFETs have continued to increase; therefore, the power dissipation of OFETs can no longer be ignored. Many research efforts have been made to develop low-power-consumption OFETs and complementary circuits. Despite the switching function, OFETs can also be utilized in emerging energy-related applications, such as near-infrared (NIR) photodetectors and organic thermoelectric devices. Organic phototransistors show considerably higher photo responsivity than other photodetector architectures due to field-effect charge modulation. The photoinduced gate modulating largely suppresses the dark current while simultaneously providing gain. These characteristics may favor NIR light detection and suggest that the organic phototransistor is a promising candidate for optoelectronic applications in the NIR regime. For organic thermoelectric applications, OFETs can work as a powerful tool for examining the charge and energy transport in the organic semiconductor, thus giving insight into organic thermoelectric studies. In this review, the authors highlight recent advances in OFET-related energy topics, including lowpower-consumption OFETs, NIR photodetectors, and organic thermoelectric devices. The remaining challenges in the field will also be discussed.

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Spontaneously formed high-performance charge-transport layers of organic single-crystal semiconductors on precisely synthesized insulating polymers

Cited by 16 publications

References 30 publications

Damage-free Metal Electrode Transfer to Monolayer Organic Single Crystalline Thin Films

Damage-free Metal Electrode Transfer to Monolayer Organic Single Crystalline Thin Films

High‐Mobility, Solution‐Processed Organic Field‐Effect Transistors from C8‐BTBT:Polystyrene Blends

Organic Field‐Effect Transistor for Energy‐Related Applications: Low‐Power‐Consumption Devices, Near‐Infrared Phototransistors, and Organic Thermoelectric Devices

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