Ultrathin organic thin‐film transistors (OTFTs) have received extensive attention due to their outstanding advantages, such as extreme flexibility, good conformability, ultralight weight, and ...compatibility with low‐cost and large‐area solution‐processed techniques. However, compared with the rigid substrates, it still remains a challenge to fabricate high‐performance ultrathin OTFTs. In this study, a high‐performance ultrathin 2,7‐dioctyl1benzothieno3,2‐b1benzothiophene (C8‐BTBT) OTFT array is demonstrated via a simple spin‐coating method, with mobility as high as 11 cm2 V−1 s−1 (average mobility: 7.22 cm2 V−1 s−1), on/off current ratio of over 106, switching current of >1 mA, and a good yield ratio as high as 100%. The ultrathin thickness at ≈380 nm and the ultralight weight at ≈0.89 g m−2 enable the free‐standing OTFTs to imperceptibly adhere onto human skin, and even a damselfly wing without affecting its flying. More importantly, the OTFTs show good electrical characteristics and mechanical stability when conformed onto the curved surfaces and even folded in a book after 100 folding cycles. These results illustrate the broad application potential of this simply fabricated ultrathin OTFT in next‐generation electronics such as foldable displays and wearable devices.
A high‐performance ultrathin organic thin‐film transistor (OTFT) array is fabricated via a solution process, with the highest mobility of 11 cm2 V−1 s−1. The thickness of ≈380 nm renders the devices with ultralight weight (≈0.89 g m−2), good conformability, and extreme flexibility. The devices show good electrical characteristics when conformed onto different curved surfaces and even folded in a book.
A room‐temperature highly‐sensitive SO2 sensor with fast response and complete recovery is constructed based on gas dielectric field‐effect transistor (FET) of CuPc single crystalline nanowire. The ...exposed conductive channel by gas dielectric is responsible for the high sensitivity to SO2 and the adsorption of the SO2 molecules dramatically enhances the field‐effect mobility. These results not only open up new opportunities to develop new SO2 sensors, but also provide an efficient way to improve the performance of organic FETs.
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The application of conductive polymer polypyrrole (PPY) towards transparent and flexible electronics has been demonstrated by a photolithography-compatible technique. The oxygen ...plasma pretreatment was found to be important for successful fabrication of PPY electrode patterns on flexible poly(ethylene terephthalate) (PET). By the patterning process of PPY, the transparency of PPY electrode can be improved up to >80% over the visible spectrum, which combined with the excellent chemical and physical stability of PPY shows the huge potential of PPY electrode as flexible transparent conductive electrode. In addition, PPY provides better interface connection for uniform deposition of organic semiconductor thin film. These outstanding advantages in PPY, coupled with selection of a novel anti-solvent and water-tolerant elastic dielectric, enable the photolithographic PPY patterns to be used for fabrication of large-scale flexible transparent organic field-effect transistor arrays. These results open up the capability of PPY as flexible transparent electrode for flexible organic devices, and exhibit a strong potential of PPY electrode patterns for future large-scale high-precision flexible electronics.
Bioelectronics in synaptic transistors for future biomedical applications, such as implanted treatments and human–machine interfaces, must be flexible with good mechanical compatibility with ...biological tissues. The rigid nature and high deposition temperature in conventional inorganic synaptic transistors restrict the development of flexible, conformal synaptic devices. Here, the dinaphtho2,3‐b:2′,3′‐fthieno3,2‐b‐thiophene organic synaptic transistor on elastic polydimethylsiloxane is demonstrated to avoid these limitations. The unique advantages of organic materials in low Young's modulus and low temperature process enable seamless adherence of organic synaptic transistors on arbitrary‐shaped objects. On 3D curved surfaces, the essential synaptic functions, such as potentiation/depression, short/long‐term synaptic plasticity, and spike voltage–dependent plasticity, are successfully realized. The time‐dependent surface potential characterization reveals the slow polarization of dipoles in the dielectric is responsible for hysteresis and synaptic behaviors. This work represents that organic materials offer a potential platform to realize the flexible, conformal synaptic transistors for the development of wearable and implantable artificial neuromorphic systems.
A flexible, conformal synaptic transistor is realized by combining highly ductile Au electrodes with low‐Young's modulus organic materials including dinaphtho2,3‐b:2′,3′‐fthieno3,2‐b‐thiophene semiconductor, organosilicone dielectric, and polydimethylsiloxane support. On 3D curved surfaces, essential synaptic functionalities are realized, including potentiation/depression, short/long‐term synaptic plasticity, and spike voltage‐dependent plasticity. The slow polarization of dipoles in the organosilicone dielectric is responsible for hysteresis in the transistor and synaptic behaviors.
Gas sensors based on organic semiconductor have recently attracted much attention due to their inherent advantages, especially excellent flexibility and good selectivity. However, the gas species ...identification with high sensing response remains a key subject for organic gas sensors. Herein, a ZnPc single nanobelt field-effect transistor with the gas dielectric was fabricated and exhibited excellent gas sensing performance at room temperature. The sensors show the high response with 220% to 10 ppm NO 2 and 3566% to 20 ppm H 2 S, and the low detection limit down to 50 ppb towards NO 2 /H 2 S, which surpass most reported room-temperature organic-based NO 2 /H 2 S sensors. Further, our single device realized accurate gas selective identification among NO 2 , SO 2 and H 2 S with 92% success ratio in LDA feature space.
Development of conformal n-channel organic phototransistor (OPT) array is urgent for future applications of organic complementary circuits in portable and wearable electronics and optoelectronics. In ...this work, the ultrathin conformal OPT array based on air-stable n-type PTCDI-C
H
was fabricated. The OPT array shows excellent electrical and photoelectrical performance, good device uniformity, and remains stable in electron mobility by 83% after 90 days compared to the initial values. Eventhough mobility, on-state current, off-state current, and photocurrent of PTCDI-C
H
thin film phototransistor show slight decrease with the decreased bending radius, the device still remains the stable photosensitivity as high as 10
when the device is freely adhered on the 2D surfaces and 3D hemispherical sphere, which is in a class with the highest photosensitivity for perylene diimide derivatives. These results present the promising application potential of our conformable air-stable n-type PTCDI-C
H
OPTs as the photodetection system of curved artificial compound eyes in wearable and portable electronics and optoelectronics.
Recently; one-dimensional (1D) nanostructure field-effect transistors (FETs) have attracted much attention because of their potential application in gas sensing. Micro/nanoscaled field-effect sensors ...combine the advantages of 1D nanostructures and the characteristic of field modulation. 1D nanostructures provide a large surface area-volume ratio; which is an outstanding advantage for gas sensors with high sensitivity and fast response. In addition; the nature of the single crystals is favorable for the studies of the response mechanism. On the other hand; one main merit of the field-effect sensors is to provide an extra gate electrode to realize the current modulation; so that the sensitivity can be dramatically enhanced by changing the conductivity when operating the sensors in the subthreshold regime. This article reviews the recent developments in the field of 1D nanostructure FET for gas detection. The sensor configuration; the performance as well as their sensing mechanism are evaluated.
At present, the direct experimental observation and confirmation of thermal damage on semiconductors remain unexplored. This report presents clear evidence of the thermal irradiation damage on the ...electrode contact region of an organic semiconductor in the electrode deposition process by applying an ultralong uniform rubrene single crystal to simultaneously fabricate vacuum-deposited electrode and stamped electrode top-contact organic field-effect transistors (OFETs). The surface potential measurements combined with the transfer characteristics show that the thermal irradiation damage causes the HOMO level of rubrene shift downwards by 0.17 eV, resulting in the enhanced contact resistance and hence the lowered field-effect mobility. This interesting experimental discovery clarifies the nature of vacuum-deposited electrode induced thermal irradiation damage on OFETs, will enhance the understanding and development of contact engineering to further improve the performance of organic electronics.
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•The thermal irradiation damage on the semiconductor is experimentally confirmed for the first time.•The stamped electrode fabrication method can completely avoid thermal irradiation on the semiconductor surface.•The stamped-electrode devices exhibit obviously higher performance than deposited-electrode devices.•The thermal irradiation enhances the charge injection barrier at the electrode/semiconductor contact interface.•The thermal irradiation increases the density of structure defects and charge traps of the rubrene single crystal.
The use of micrometer and nanometer‐sized organic single crystals to fabricate devices can retain all the advantages of single crystals, avoid the difficulties of growing large crystals, and provide ...a way to characterize organic semiconductors more efficiently. Moreover, the effective use of such “small” crystals will be beneficial to nanoelectronics. Here we review the recent progress of organic single‐crystalline transistors based on micro‐/nanometer‐sized structures, namely fabrication methods and related technical issues, device properties, and current challenges.
“Small”‐crystalline transistors, where “small” means nano‐ or micrometer sized, are of interest for micro‐ and nanoelectronic devices. The remarkable progress made recently in controlled synthesis of micro/nanometer‐sized organic single crystals, new device fabrication techniques (one of which is illustrated in the figure), and device performance of “small”‐crystalline transistors is described and the advantages of such devices are outlined.
To date, the functional application of the flexible organic single-crystal devices in strain sensors has not been studied. In this letter, the excellent flexibility of the beltlike rubrene single ...crystals enables the rubrene single-crystal field-effect transistors to be bent inward and outward, and their electrical properties under compressive and tensile strain are demonstrated. The current and mobility of the device show the nearly linear changes under the tensile and compressive strain of <;0.4%. The dynamic response of the strain presents good repeatability. The calculated sensitivity under tensile strain is two orders of magnitude higher than the previously reported organic thin-film-based strain sensor. It is demonstrated that the rubrene single-crystal device can effectively detect the movement of a human finger. These results exhibit the promising potential of our transistors in artificial intelligence and healthcare systems.
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