Visualizing Quasi‐Static Electric Fields with Flexible and Printed Organic Transistors

Shoji, Itsuki; Wada, Hideki; Uto, Kodai; Takeda, Yasunori; Sugimoto, Toshiyuki; Matsui, Hiroyuki

doi:10.1002/admt.202100723

Cited by 8 publications

(1 citation statement)

References 30 publications

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“…Shoji et al studied frequency characteristic of an organic FET device with DTBDT-C6 as active layer. [41] AC voltage was applied to an aluminum foil as a charged object, while the device-to-object gap was replaced by a 1 mm thick glass slide, rather than air gap. Their work indicated that, when AC voltage frequency was below 1 kHz, no phase delay occurred between the AC voltage signal applied to the Al foil and the drain current response from the device, while observable phase delay occurred when the frequency was higher than 10 kHz.…”

Section: Proximity Sensingmentioning

confidence: 99%

A Multifunctional Flexible Ferroelectric Transistor Sensor for Electronic Skin

Liu

Dong

Zeng

et al. 2021

Adv Materials Inter

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Electronic skin (E‐skin) is a device that mimics the functions of human skin and is attracting more and more attention as a novel platform for human–machine interaction, health diagnostics, therapeutics, robotics, prosthesis, and monitoring. Here, a flexible ferroelectric field‐effect transistor (FeFET) is developed as a multifunctional sensor prototype for electronic skin. Ferroelectric poly(vinylidene fluoride trifluoroethylene) and amorphous tungsten‐doped indium oxide are utilized to construct the FeFET. The device possesses three‐in‐one sensing performance. It can monitor external stress with a linear sensitivity of 4.6 nA kPa−1 in broad pressure range between 50 Pa and 150 kPa and detect temperature change between 0 and 70 °C. Electrostatic interaction further endows the device with proximity sensing function to perceive the approach of a charged object. The device is further developed for detection of a human's physiological signals, such as pulsation and respiration, and finger's action. It shows good bending endurance which maintains its transfer characteristic after 1000 cycles of bending operation. Moreover, the device's responses to both temperature change and charged objects are investigated when it is under bending condition with radius of curvature down to 1.09 mm. This multifunctional sensor prototype is expected to contribute to the next‐generation E‐skin.

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Section: Proximity Sensingmentioning

confidence: 99%

A Multifunctional Flexible Ferroelectric Transistor Sensor for Electronic Skin

Liu

Dong

Zeng

et al. 2021

Adv Materials Inter

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Printed 700 V/V Gain Amplifiers Based on Organic Source‐Gated Transistors with Field Plates

Hemmi

Ikeda

Sporea

et al. 2023

Adv Elect Materials

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of over 4 cm 2 V −1 s −1 and high deposition speed of 2.4 m min −1 , depending on the type of printing method. [4] In addition, the precise selection of organic solvents such as anisole and 3-methylcyclohexanone may enable devices to be fabricated with less environmental impact than conventional methods. [5] Therefore, devices fabricated by the printing process will be an important factor in realizing a sustainable development goals (SDGs) in the future. [6] The unique and outstanding characteristics of printed OTFTs have led to their application in amplifiers for flexible and wearable sensor devices. [7] It has been believed that reducing the energy barrier at source and drain electrodes is important for improving the circuit performances. [8] So far, many circuit applications of OTFTs that exhibit good charge injection have been reported. However, obtaining high enough gain usually requires multistage OTFT amplifiers, which increase the complexity, circuit size, and fabrication cost. Reducing power consumption is also important for wearable devices with a small power source.Source-gated transistor (SGT) was first demonstrated with amorphous silicon by Shannon and Gerstner in 2003. [9] SGT utilizes a Schottky barrier at source electrode and controls the current by gating the barrier instead of gating the channel region. [10] Although the maximum current is decreased by the introduction of the Schottky barrier, SGT has advantages in high gain and small device variability. The high gain originates from the high-output resistance in saturation regime. Because of the pinch off near the source electrode instead of the drain electrode, SGT exhibits an excellent saturation behavior. SGT performance is less sensitive to the channel length because the current is controlled by the electrode but not the channel. This is important in printed electronics, where the geometry variation is significant. A phenomenon similar to SGT with organic semiconductors was first reported with a numerical simulation by Rapisarda and co-workers in 2013. [11] Then, Nathan and co-workers applied the printed organic SGT (OSGT) to multistage amplifier circuits with p-type organic semiconductor C8-BTBT in 2019. [12] The OSGT exhibited several superior performances such as high gain of 260 V/V, steep subthreshold slope (60 mV dec −1 ), and small device variability. The first n-type OSGT using N2200 as an organic semiconductor was reported in 2022. [13] Although SGT has such a high potential, [14] it has been also known that the saturation behavior can be severely deteriorated Printed amplifiers are promising components for flexible and wearable devices. The circuits need to have small footprint, high amplification, and low power consumption, which is not simultaneously possible with conventional thin-film transistors because multiple stages are required and introduce sources of variability, failure, or wasted area. Source-gated transistors (SGTs) can in principle have extremely high intrinsic gain but this is not always the case because of latera...

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