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The progress of brain synaptic devices has witnessed an era of rapid and explosive growth. Because of their integrated storage, excellent plasticity and parallel computing, and system information processing abilities, various field effect transistors have been used to replicate the synapses of a human brain. Organic semiconductors are characterized by simplicity of processing, mechanical flexibility, low cost, biocompatibility, and flexibility, making them the most promising materials for implanted brain synaptic bioelectronics. Despite being used in numerous intelligent integrated circuits and implantable neural linkages with multiple terminals, organic synaptic transistors still face many obstacles that must be overcome to advance their development. A comprehensive review would be an excellent tool in this respect. Therefore, the latest advancements in implantable neural links based on organic synaptic transistors are outlined. First, the distinction between conventional and synaptic transistors are highlighted. Next, the existing implanted organic synaptic transistors and their applicability to the brain as a neural link are summarized. Finally, the potential research directions are discussed. [ABSTRACT FROM AUTHOR]

The attachment of display devices to various objects has attracted much attention due to their ability to present visual information to people in different environments. Such devices should be ultrathin to ensure complete coverage when attached to various objects, making them a critical technology for the development of rollable and stretchable displays. In this study, the fabrication of high‐performance ultrathin oxide thin‐film transistors (TFTs) on a 5 µm‐thick polyethylene terephthalate substrate is demonstrated by the method of delamination and transfer. Molybdenum oxide functions as an exfoliation layer, and the ultrathin devices exhibit full coverage on various objects with complex surface profiles such as contact lens, fabric, and human skin. It is notable that the TFT device exhibits a high optical transparency of greater than 81% and a reasonable electrical performance with a high mobility of 37 cm2 V−1 s−1. Since the oxide TFTs are fabricated without temperature limitations, the devices show reliable electrical performances under gate and illumination stresses. The flexible devices also exhibit excellent transfer characteristics in the bending state, regardless of the bending radius and direction, as well as a high mechanical durability of over 10 000 bending cycles with the bending radius of 3 mm. [ABSTRACT FROM AUTHOR]

Donor–acceptor copolymer‐based field‐effect transistors (FETs) have attracted considerable attention from technological and academic perspectives due to their low band gap, high mobility, low cost, and easy solution processability, flexibility, and stretch ability. Among different solution‐processing techniques, meniscus‐guided coating has the potential for large‐area film formation. Moreover, 29‐diketopyrrolopyrroleselenophene vinylene selenophene (29‐DPP‐SVS) donor‐acceptor copolymer‐based FETs have already exhibited excellent performance due to their short π–π stacking distance and strong π–π interaction. Charge carrier mobility of these types of semiconducting materials is significantly dependent on the applied electric field. Therefore, detailed analysis of the electric‐field dependency of charge carrier mobility is necessary to understand the transport mechanisms within these materials. Thus, herein, 29‐DPP‐SVS‐based FETs are fabricated by varying the blade‐coating speed of their semiconductor layer. Then, the effect of the blade‐coating speed on the electrical properties of the FETs is studied through the analysis of electric‐field‐dependent mobility. The results suggest that the charge carrier mobility of different FETs is dependent on the applied electric field and that the type of dependency is Poole–Frenkel. At an optimized blade‐coating speed (2 mm s−1), the device exhibits maximum zero‐field mobility (3.39 cm2 V−1 s−1) due to the low trap density within the conducting channel. [ABSTRACT FROM AUTHOR]

We describe how the off-state current (Ioff) property of amorphous InGaZnO (a-IGZO) thin-film transistors is caused by trap-assisted tunneling (TAT) by using a two-dimensional device simulation software application (Atlas 2 D, Silvaco). We found that Ioff can be increased by controlling the bandgap energy (EG) and the effective mass of electron (me) of a-IGZO transistors. When me was increased from 0.32 to 0.38 mo (mass of a free electron), the point at which Ioff started to increase in the region of negative gate voltage (VGS) shifted from −4.7 to −7.4 V. In addition, when EG was changed from 3.05 to 3.2 eV, the average value of Ioff changed from 3.13 × 10−13 to 2.4 × 10−14 A. This implies that EG and me influence the increase in Ioff in a-IGZO TFTs because of the difficulty associated with TAT. [ABSTRACT FROM AUTHOR]

We fabricate high-performance solution-processed SnO2 thin-film transistors (TFTs) exhibiting improved carrier transport features by exposing the ultraviolet/ozone (UV/O3) on the SnO2 film during the pre-annealing stage. The SnO2 layer is treated with different UV/O3-exposure times from 0 to 60 minutes before the post-annealing step. As UV/O3-exposure time increases from 0 to 30 minutes, the M-O-M (M, metal; and O, oxygen) network, mass density, and oxygen vacancies of films are enhanced. In contrast, the M-O-M network and mass density decrease, while the oxygen vacancies rather increase when the UV/O3-exposure time reaches 60 minutes beyond 30 minutes. The SnO2 (Sn4+) phase, thickness, and surface morphology of SnO2 films are not considerably changed regardless of UV/O3-exposure time. When the UV/O3-exposure time is 30 minutes, devices demonstrate superior field-effect mobility (10.1 cm2 V−1 s−1) at approximately two times higher than the TFT without UV/O3-exposure. Furthermore, the SnO2 TFT with UV/O3-exposure time for 30 minutes shows improved subthreshold-swing characteristics and a high on/off current ratio. These devices are adequate for use in high-resolution active-matrix LCDs or OLED displays that demand a high field-effect mobility (>10 cm2 V−1 s−1) and on/off ratio (>106). [ABSTRACT FROM AUTHOR]

We have investigated the effect of electron effective mass (me*) and tail acceptor-like edge traps density (NTA) on the electrical characteristics of amorphous-InGaZnO (a-IGZO) thin-film transistors (TFTs) through numerical simulation. To examine the credibility of our simulation, we found that by adjusting me* to 0.34 of the free electron mass (mo), we can preferentially derive the experimentally obtained electrical properties of conventional a-IGZO TFTs through our simulation. Our initial simulation considered the effect of me* on the electrical characteristics independent of NTA. We varied the me* value while not changing the other variables related to traps density not dependent on it. As me* was incremented to 0.44 mo, the field-effect mobility (µfe) and the on-state current (Ion) decreased due to the higher sub-gap scattering based on electron capture behavior. However, the threshold voltage (Vth) was not significantly changed due to fixed effective acceptor-like traps (NTA). In reality, since the magnitude of NTA was affected by the magnitude of me*, we controlled me* together with NTA value as a secondary simulation. As the magnitude of both me* and NTA increased, µfe and Ion deceased showing the same phenomena as the first simulation. The magnitude of Vth was higher when compared to the first simulation due to the lower conductivity in the channel. In this regard, our simulation methods showed that controlling me* and NTA simultaneously would be expected to predict and optimize the electrical characteristics of a-IGZO TFTs more precisely. [ABSTRACT FROM AUTHOR]

In this work, operationally and mechanically stable organic field‐effect transistors (OFETs) are demonstrated on aramid fiber‐based paper enabled by a simple and universal surface planarization method. By employing a nanoimprint lithography‐inspired surface smoothening method, rough aramid paper is successfully smoothened from a scale of several tens of micrometers to a sub‐nanometer‐scale surface roughness. Owing to the sub‐nanometer‐scale surface roughness of the aramid paper, the OFETs fabricated on the aramid paper exhibit decent field‐effect mobility (0.25 cm2 V−1 s−1) with a high current on‐to‐off ratio (>107), both of which are comparable with those of OFETs fabricated on rigid silicon substrates. Moreover, the OFETs fabricated on the aramid paper exhibit both high operational and mechanical stability; this is indicated by a bias‐stress‐induced threshold voltage shift (∆VTH ≈ 4.27 V under an excessive gate bias stress of 1.7 MV cm−1 for 1 h 30 min) comparable to that of OFETs on a rigid silicon substrate, moderate field‐effect mobility, and a threshold voltage stability under 1000 bending cycles with a compressive strain of 1%. The demonstration of highly stable OFETs on paper enabled by the simple planarization method will expand the potential use of various types of paper in electronic applications. [ABSTRACT FROM AUTHOR]

This review elucidates the potential of Organic Thin Film Transistors (OTFTs) for biocompatible synaptic devices in in-vivo medical applications. Emphasizing attributes like flexibility and reduced environmental footprint, OTFTs are distinguished from traditional silicon counterparts. The synthesis of electronic capabilities and biological emulation in synaptic transistors is dissected, spotlighting their role in neuromorphic computing. This exploration centers on biocompatibility, detailing criteria, challenges, and the integration of organic electronics with living systems. Furthermore, potential applications, innovations, and future prospects of OTFT-driven synaptic devices are addressed. Critical technical, ethical, and societal challenges within this interdisciplinary nexus are outlined. The confluence of OTFTs, synaptic transistors, and biocompatibility heralds a paradigm shift in techno-biological convergence. [Display omitted] • Organic thin film transistors (OTFTs) enhance biocompatible synaptic devices. • Superiority of OTFTs: Flexibility, cost-effectiveness, biocompatibility. • OTFTs pave the way for transformative human-technology interactions. • Research underscores OTFTs' indispensable role in organic electronics. • Continued research vital to fully harness OTFTs' potential. [ABSTRACT FROM AUTHOR]

• Morphological and electrical characteristics of patterned OSCs are investigated. • Contact line curvature-induced molecular misorientation effect, is demonstrated. • Patterned TIPS-pentacene on the 50 µm width showed the lowest misorientation angle. • The contact line curvature-induced misorientation angle affected charge transport properties. The printing of organic semiconductors (OSCs) by means of meniscus guided coating (MGC) has great potential for the fabrication of high-performance, uniform, and large area flexible electronics. Furthermore, surface energy patterning allows low-cost, large area manufacturing, and is a requirement for device isolation to achieve accurate drive and to minimize power consumption. We investigated the morphological and electrical characteristics of surface energy patterned OSCs coated using the MGC method. A unique phenomenon, contact line curvature-induced molecular misorientation effect, which occurs in the patterning of OSCs with the MGC method, is demonstrated. This effect is highly dependent on the pattern width which decided contact line curvature. It influences the charge transport properties and hence the field-effect mobility of organic thin-film transistors (OTFTs). OTFTs in widths ranging from 50 to 500 µm were fabricated. The highest misorientation angle was induced in the 50 µm pattern width and the corresponding OTFTs exhibited the highest mobility. [ABSTRACT FROM AUTHOR]