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Advancements in electronic device technology have led to an exponential growth in demand for more efficient and versatile transistors. In this context, organic field-effect transistors (OFETs) have emerged as a promising alternative due to their unique properties and potential for flexible and low-cost applications. However, to overcome some of the inherent limitations of OFETs, the integration of organic materials with other materials and technologies has been proposed, giving rise to a new generation of hybrid devices. In this article, we explore the development and advances of organic field-effect transistors and highlight the growing importance of hybrid devices in this area. In particular, we focus on three types of emerging hybrid devices: organic electrochemical transistors (OECTs), organic light-emitting field-effect transistors (OLEFETs) and organic field-effect waveguides (OFEWs). These devices combine the advantages of organic materials with the unique capabilities of other technologies, opening up new possibilities in fields such as flexible electronics, bioelectronics, or optoelectronics. This article provides an overview of recent advances in the development and applications of hybrid transistors, highlighting their crucial role in the next generation of electronic devices. [ABSTRACT FROM AUTHOR]

The molecular packing of the organic semiconductors significantly influences charge transport in organic field-effect transistors (OFETs). In addition, a pronounced impact of the dielectric layer is observed on the charge conduction within the few monolayers above the semiconductor–dielectric interfaces. This study highlighted the hysteresis and charge transport behavior of a nanocomposite dielectric-based OFET across a broad range of measurement temperatures spanning from 50 to 350 K. The influence of the dielectric layer blooms at around 100 K measurement temperature, where a prominent crossover in hysteresis has taken place in both the dual sweep transfer curves and C–V curves. The activation energy shifts from low to high due to hysteresis reversal at 100 K. Carrier mobility supports hopping-assisted charge transport. Experimental evidence shows that polarization of gold nanoparticles due to the gate field affects charge conduction at cryogenic temperatures, while trap states dominate polarization at elevated temperatures. [ABSTRACT FROM AUTHOR]

The backwardness of n‐type organic semiconductors still exists compared with the p‐type counterparts. Thus, the development of high‐performance n‐type organic semiconductors is of great importance for organic electronic devices and their integrated circuits. In recent years, azabenzannulated perylene diimide (PDI), as one of immense bay‐region‐annulated PDI derivatives, has drawn considerable attentions. However, the electronic mobilities of azabenzannulated PDI derivatives are barely satisfactory. In this contribution, the peripheral benzene ring in azabenzannulated PDI 2 was fused to the ortho position by intramolecular C−H arylation cyclization. This endows the resultant azabenzannulated PDI 4 a planar configuration as well as electron deficient pentagonal ring. As a result, the electronic mobility of 4 is almost two orders of magnitude higher than that of the nonfused azabenzannulated PDI 2. This work shall pave a new avenue in elevating the performance of azabenzannulated PDI in organic electronics. [ABSTRACT FROM AUTHOR]

Advancements in electronic device technology have led to an exponential growth in demand for more efficient and versatile transistors. In this context, organic field-effect transistors (OFETs) have emerged as a promising alternative due to their unique properties and potential for flexible and low-cost applications. However, to overcome some of the inherent limitations of OFETs, the integration of organic materials with other materials and technologies has been proposed, giving rise to a new generation of hybrid devices. In this article, we explore the development and advances of organic field-effect transistors and highlight the growing importance of hybrid devices in this area. In particular, we focus on three types of emerging hybrid devices: organic electrochemical transistors (OECTs), organic light-emitting field-effect transistors (OLEFETs) and organic field-effect waveguides (OFEWs). These devices combine the advantages of organic materials with the unique capabilities of other technologies, opening up new possibilities in fields such as flexible electronics, bioelectronics, or optoelectronics. This article provides an overview of recent advances in the development and applications of hybrid transistors, highlighting their crucial role in the next generation of electronic devices.

Nowadays, virus pandemics have become a major burden seriously affecting human health and social and economic development. Thus, the design and fabrication of effective and low-cost techniques for early and accurate virus detection have been given priority for prevention and control of such pandemics. Biosensors and bioelectronic devices have been demonstrated as promising technology to resolve the major drawbacks and problems of the current detection methods. Discovering and applying advanced materials have offered opportunities to develop and commercialize biosensor devices for effectively controlling pandemics. Along with various well-known materials such as gold and silver nanoparticles, carbon-based materials, metal oxide-based materials, and graphene, conjugated polymer (CPs) have become one of the most promising candidates for preparation and construction of excellent biosensors with high sensitivity and specificity to different virus analytes owing to their unique π orbital structure and chain conformation alterations, solution processability, and flexibility. Therefore, CP-based biosensors have been regarded as innovative technologies attracting great interest from the community for early diagnosis of COVID-19 as well as other virus pandemics. For providing precious scientific evidence of CP-based biosensor technologies in virus detection, this review aims to give a critical overview of the recent research related to use of CPs in fabrication of virus biosensors. We emphasize structures and interesting characteristics of different CPs and discuss the state-of-the-art applications of CP-based biosensors as well. In addition, different types of biosensors such as optical biosensors, organic thin film transistors (OTFT), and conjugated polymer hydrogels (CPHs) based on CPs are also summarized and presented. [ABSTRACT FROM AUTHOR]

In the field of optoelectronics, Organic Light Emitting Transistors (OLET) symbolise a new era. The OLET is a bifunctional device that combines the switching and amplification capabilities of organic field effect transistors with the electroluminescent capabilities of organic light emitting diodes in a single device. Organic semiconductor materials are important for optoelectronic devices because of their low cost, light weight, and flexible production procedures. OLETs play a vital role in the field of high mobility organic semiconductors and the fabrication of high performance organic optoelectronic devices as organic optoelectronic devices progress. The performance of OLETs with anthracene as an organic semiconductor material is discussed in detail in this research paper. The performance of OLETs is evaluated using a state-of-the-art Atlas Silvaco 2-D Simulator in terms of driving current, mobility, and current-on-off ratio. The device's output properties are also examined, and these values are then compared to the available dataset. The parameter values are as follows: Ids of 17 μ A , mobility of 12 × 10 - 2 cm 2 / Vs and on-off ratio of 10 7 . We have also calculated power consumption value (0.54 mW). We can see that this device has much higher mobility value and lower power consumption value which makes it the better performance device. [ABSTRACT FROM AUTHOR]

Flexible organic field-effect transistors (OFETs) based on solution-processed TIPS-Pentacene as semiconductor and high- ${k}$ P(VDF-TrFE) gate dielectric are successfully demonstrated on fabric for future electronic textile (e-textile) applications. These devices exhibited very high electrical performance with maximum ($\mu _{{\mathrm {max}}}$) and average ($\mu _{{\mathrm {avg}}}$) field-effect mobility values of ~1.2 and ~0.5(±0.3) ${\mathrm {cm}}^{2}\cdot {\mathrm {V}}^{-1}\cdot {\mathrm {s}}^{-1}$ , respectively, in the saturation regime and ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ of ~103 for a low operating voltage of −5 V, along with excellent electromechanical stability. Furthermore, these devices showed excellent environmental stability with almost unchanged electrical characteristics for 26 weeks. Moreover, devices showed high cyclic stability with stable ON/ OFF switching characterized up to 500 cycles. [ABSTRACT FROM AUTHOR]

The development of n-type organic semiconductors (OSCs) has been lagged behind that of p-type OSCs, mainly due to the limited availability of the electron deficient π-conjugated backbones and facile electron trapping by ambient oxidants. Improving the performance of n-type OSCs through n-doping is essential for realizing p-n junction diodes and complementary circuits. Conventional vacuum deposition doping is costly and time-consuming, while solution doping risks thermal damage through necessary annealing. Therefore, the development of a simpler, more affordable n-doping method is crucial. In this study, we have developed a solution-processed n-doping method using an organic cationic dye in a low boiling point solvent that can be dried at room temperature in 1 h, which eliminates the need for annealing. The effects of different organic cationic dyes and reducing agents on the n-type OSC were evaluated. After n-doping, electron mobility and photoresponsivity in the sample increased by 5.5 and 20 times, respectively, compared to undoped samples. Furthermore, there was no significant degradation in the electron mobility of the n-doped samples under ambient conditions after 15 days. Studying n-doping with various organic cationic dyes in different OSC materials, embracing further research into their applications and mechanisms, would advance the field of organic electronics.

A naphthalene diimide (NDI)-based small molecule with a thienothiophene linker (NDI-TT-NDI) was synthesized for use as a semiconductor layer in solution-processable n-type organic field-effect transistors (OFETs). The thienothiophene linker was introduced to the donor site between the two NDIs to impart planarity to the molecular backbone, which is favorable for inducing high crystallinity, and the morphological and crystal characteristics of the resulting film were analyzed. An additional annealing treatment applied to the NDT-TT-NDI films changed their orientation such that the molecular ordering and crystallinity of the film were significantly improved at a specific annealing temperature. The optimally annealed NDI-TT-NDI film exhibited a distinct edge-on molecular orientation with a narrow intermolecular π−π stacking distance, which is advantageous for lateral charge transport along the stacks. Consequently, an optimally annealed NDI-TT-NDI-based OFET exhibited electron mobilities of up to 0.032 cm2V−1s−1 and an on/off ratio of 1.0 × 107. [ABSTRACT FROM AUTHOR]

Nowadays, virus pandemics have become a major burden seriously affecting human health and social and economic development. Thus, the design and fabrication of effective and low-cost techniques for early and accurate virus detection have been given priority for prevention and control of such pandemics. Biosensors and bioelectronic devices have been demonstrated as promising technology to resolve the major drawbacks and problems of the current detection methods. Discovering and applying advanced materials have offered opportunities to develop and commercialize biosensor devices for effectively controlling pandemics. Along with various well-known materials such as gold and silver nanoparticles, carbon-based materials, metal oxide-based materials, and graphene, conjugated polymer (CPs) have become one of the most promising candidates for preparation and construction of excellent biosensors with high sensitivity and specificity to different virus analytes owing to their unique π orbital structure and chain conformation alterations, solution processability, and flexibility. Therefore, CP-based biosensors have been regarded as innovative technologies attracting great interest from the community for early diagnosis of COVID-19 as well as other virus pandemics. For providing precious scientific evidence of CP-based biosensor technologies in virus detection, this review aims to give a critical overview of the recent research related to use of CPs in fabrication of virus biosensors. We emphasize structures and interesting characteristics of different CPs and discuss the state-of-the-art applications of CP-based biosensors as well. In addition, different types of biosensors such as optical biosensors, organic thin film transistors (OTFT), and conjugated polymer hydrogels (CPHs) based on CPs are also summarized and presented.

Sensors and Internet of Things (IoT) have been revolutionizing our world by establishing a smart and more sustainable environment. Low-temperature processing and chemical functionality of organic semiconductors, high- k of natural dielectric materials, and mechanically flexible substrates make organic field-effect transistor (OFET)-based sensors an attractive alternative in many fields which includes biomedical, security, environment, and neuromorphic computing technologies. One of the most striking application areas of OFETs is their use as artificial synapses. Indeed, several (opto)electronic field-effect devices have recently been proposed to simulate synaptic functions of the biological brain. OFETs offer excellent opportunities to replace the conventional von Neumann's computing systems. Among the sensor devices used to build artificial synapses, OFETs are one of the most promising candidates for neuromorphic computers and bioelectronics owing to their easy processing, flexible device configuration, mechanical bendability, low cost, biocompatibility, and ductility. As such, organic phototransistors (OPTs) have attracted tremendous attention due to their many advantages, namely the facile preparation process, easy integration, and tunable optoelectronic properties over various device configurations. Moreover, the use of OPTs to emulate the unique properties of biological synapses is regarded as the key to the advancements of artificial intelligence (AI). Herein, we first review the fabrication and operating mechanisms of OFETs and OPTs. The recent developments and applications of organic phototransistors as artificial synapses are thereafter described and discussed. [Display omitted] [ABSTRACT FROM AUTHOR]

In this review, recent advances in compact modeling of organic field-effect transistors (OFETs) are presented. Despite the inherent strength for printed flexible electronics and the extremely aggressive research conducted over more than three decades, the OFET technology still seems to remain at a relatively low technological readiness level. Among various possible reasons for that, the lack of a standard compact model, which effectively bridges the device- and system-level development, is clearly one of the most critical issues. This article broadly discusses the essential requirements, up-to-date progresses, and imminent challenges for the OFET compact device modeling toward a universal, physically valid, and applicable description of this fast-developing technology.

We examine the electrostatic discharge (ESD) behavior of bottom-gate bottom-contact pentacene organic field-effect transistor (OFET) devices with a parylene-C gate dielectric. A comparison between devices with gate and contact overlap geometries of −2 to $3~\mu \text{m}$ are analyzed. In particular, the relationship between contact overlap, the protective effect of the increased overlap, and the electric field in the dielectric and their effect on ESD resilience is detailed. We find a markedly increased tolerance for negative contact overlaps and a small decrease in tolerance for more positive overlaps. We also report on a highly resilient effect where OFET devices continue to operate but with a reduction in performance after multiple dielectric breakdown. A negative overlap length should be carefully considered when designing OFET devices in a tradeoff between decreased performance and higher ESD resilience. [ABSTRACT FROM AUTHOR]

The functionalization of polymer dielectrics with self‐assembly monolayer is still a big issue to be resolved due to the lack of particular anchoring sites on their surface for specific binding. To this end, hydroxyl groups are a kind of commonly used anchoring sites, which can be effectively produced on polymer surface by oxygen plasma treatment. In this work, the modification methods are investigated and the assembly conditions of self‐assembly monolayer are characterized on the surface of low‐k polyimide (PI) gate dielectric layers. As a result, the device performance can be enhanced by an order of magnitude under the optimal modified state compared with the initial state. In addition, the charge transport mechanism of organic semiconductor on PI surface is studied through temperature‐variable experiments. Furthermore, organic logic circuits (NAND gate, NOR gate, inverter, and oscillator) are manufactured using modified PI as insulating layers. The functionalization of polymer dielectrics with self‐assembly monolayer offers an effective strategy to improve the device performance in organic electronics. [ABSTRACT FROM AUTHOR]

Numerous strategies are developed to impart stretchability to polymer semiconductors. Although these methods improve the ductility, mobility, and stability of such stretchable semiconductors, they nonetheless still need further improvement. Here, it is shown that 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ) is an effective molecular additive to tune the properties of a diketopyrrolopyrrole‐based (DPP‐based) semiconductor. Specifically, the addition of F4‐TCNQ is observed to improve the ductility of the semiconductor by altering the polymer's microstructures and dynamic motions. As a p‐type dopant additive, F4‐TCNQ can also effectively enhance the mobility and stability of the semiconductor through changing the host polymer's packing structures and charge trap passivation. Upon fabricating fully stretchable transistors with F4‐TCNQ‐DPP blended semiconductor films, it is observed that the resulting stretchable transistors possess one of the highest initial mobility of 1.03 cm2 V−1 s−1. The fabricated transistors also exhibit higher stability (both bias and environmental) and mobility retention under repeated strain, compared to those without F4‐TCNQ additive. These findings offer a new direction of research on stretchable semiconductors to facilitate future practical applications. [ABSTRACT FROM AUTHOR]

Highly crystalline thin films in organic semiconductors are important for applications in high‐performance organic optoelectronics. Here, the effect of grain boundaries on the Hall effect and charge transport properties of organic transistors based on two exemplary benchmark systems is elucidated: (1) solution‐processed blends of 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) small molecule and indacenodithiophene‐benzothiadiazole (C16IDT‐BT) conjugated polymer, and (2) large‐area vacuum evaporated polycrystalline thin films of rubrene (C42H28). It is discovered that, despite the high field‐effect mobilities of up to 6 cm2 V−1 s−1 and the evidence of a delocalized band‐like charge transport, the Hall effect in polycrystalline organic transistors is systematically and significantly underdeveloped, with the carrier coherence factor α < 1 (i.e., yields an underestimated Hall mobility and an overestimated carrier density). A model based on capacitively charged grain boundaries explaining this unusual behavior is described. This work significantly advances the understanding of magneto‐transport properties of organic semiconductor thin films. [ABSTRACT FROM AUTHOR]

The sensitivity of conventional thin‐film OFET‐based sensors is limited by the diffusion of analytes through bulk films and remains the central challenge in sensing technology. Now, for the first time, an ultrasensitive (sub‐ppb level) sensor is reported that exploits n‐type monolayer molecular crystals (MMCs) with porous two‐dimensional structures. Thanks to monolayer crystal structure of NDI3HU‐DTYM2 (NDI) and controlled formation of porous structure, a world‐record detection limit of NH3 (0.1 ppb) was achieved. Moreover, the MMC‐OFETs also enabled direct detection of solid analytes of biological amine derivatives, such as dopamine at an extremely low concentration of 500 ppb. The remarkably improved sensing performances of MMC‐OFETs opens up the possibility of engineering OFETs for ultrasensitive (bio)chemical sensing. [ABSTRACT FROM AUTHOR]

We report light-induced negative organic magnetoresistance (OMAR) measured in ambient atmosphere in solution-processed 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) planar hybrid devices with two different device architectures. Hybrid electronic devices with trench-isolated electrodes (HED-TIE) having a channel length of ca. 100 nm fabricated in this work and, for comparison, commercially available pre-structured organic field-effect transistor (OFET) substrates with a channel length of 20 µm were used. The magnitude of the photocurrent as well as the magnetoresistance was found to be higher for the HED-TIE devices because of the much smaller channel length of these devices compared to the OFETs. We attribute the observed light-induced negative magnetoresistance in TIPS-pentacene to the presence of electron–hole pairs under illumination as the magnetoresistive effect scales with the photocurrent. The magnetoresistance effect was found to diminish over time under ambient conditions compared to a freshly prepared sample. We propose that the much faster degradation of the magnetoresistance effect as compared to the photocurrent was due to the incorporation of water molecules in the TIPS-pentacene film.

We present a drain current model and a consistent parameter extraction method for organic field-effect transistors (OFETs) considering the gate voltage-dependent contact resistance and mobility by power-law. The physical origin of the asymptotic power-law dependence of contact resistance is elaborated based on the current crowding model. The parameters of a new model can be completely extracted without ambiguity by the proposed extraction method based on the linear fitting. Pentacene-based OFETs with the Au source/drain contact in a staggered configuration experimentally validate the proposed model and the extraction method, which further reveal the bulk resistivity as the major contribution to contact resistance. [ABSTRACT FROM AUTHOR]

High-dielectric constant (κ) materials have been extensively investigated for several potential applications, particularly in low-voltage-operating organic field-effect transistors (OFETs). To ensure the operational stability of the OFET, the interface between the organic semiconductor and the high- κ dielectric should be fully controlled. In the current work, we overcoated a fluorinated polymer, namely poly(pentafluorostyrene) (PFS), onto one of the high- κ materials, namely barium titanate (BaTiO 3), and used this bilayer to fabricate highly stable OFETs. The surfaces of the BaTiO 3 dielectric layers were effectively modified with the PFS overcoating. Compared to the uncoated BaTiO 3 , the PFS/BaTiO 3 bilayer dielectric showed significantly reduced leakage current and altered surface properties. The smoothness of the surfaces of the PFS/BaTiO 3 films appeared to have been responsible for the observed improved crystal structures of the overlying pentacene molecules. In addition, the surface dipoles and electron-withdrawing character of the PFS/BaTiO 3 films built a high hole injection barrier between the semiconductor and dielectric layers, with this barrier blocking hole trapping. Finally, overcoating BaTiO 3 with PFS allowed the resulting PFS/BaTiO 3 to be utilized as a gate dielectric layer for highly stable OFETs during low-voltage operation. These OFETs exhibited hysteresis-free transistor performances and reliable operation under a sustained gate-bias stress in air. • Fluorinated polymer was overcoated on high- κ BaTiO 3 dielectric film. • Overcoating of the fluorinated polymer allowed BaTiO 3 film to exhibit good surface morphologies, insulating properties. • The OFETs prepared with fluorinated polymer/BaTiO 3 dielectric film improved reliable performances under gate-bias stress. [ABSTRACT FROM AUTHOR]

Ketopyrrolopyrrole-thieno[3,2-b] thiophene (DPPT-TT) and indacenodithiophene-co-enzothiadiazole (IDT-BT) were employed for organic field-effect transistors (OFETs) to understand the effects of semiconductor channel thickness on electrical properties. The mobility was found nearly constant, whereas the threshold voltage, contact resistance, and subthreshold slope reached an optimum at a semiconductor layer thickness of about 40 nm. This value was related to the height of the source/drain electrodes. The device performance could be degraded when the thickness of semiconductor film is higher or lower than this critical value. Two different mechanisms are proposed to explain the experimental results. [ABSTRACT FROM AUTHOR]

Abstract The stability in terms of electrical, mechanical and thermal performance, is highly desirable for practical application of flexible electronics. Here, we report the stability improvement for pentacene-based flexible organic filed-effect transistors (OFETs) with complementary polymeric dielectrics, in which the net structured cross-linked poly(4-vinylphenol) (cPVP) layer was sandwiched between two ultrathin poly-(methyl methacrylate) (PMMA) layers. The core-shell-like structured dielectrics showed improved electrical insulating property by tuning the surface morphology and termination of the pinholes, enabling a 4 V-driven flexible OFET device with a high mobility of 0.72 cm2/V and excellent bias-stress stability in air. Under the tensile bending strain, the relationship between the parallel/vertical bending directions, dynamic or static bending modes and device performances were quantitatively investigated. Moreover, this flexible OFETs has a thermal operation margin up to at least 90 °C. The interfacial compatibility between the top PMMA layer and Pentacene was responsible for the enhanced stability performances. Our approach provides future possibilities of using hybrid polymeric dielectrics for highly stable flexible OFETs. Graphical abstract Image 1 Highlights • Complementary polymeric dielectrics were proposed for rational design of highly stable flexible OFETs. • Collaborative improvements in bias-stress stability, mechanical stability and thermal stability were realized. • Complementary polymeric dielectrics afford enhanced interfacial compatibility. • Ultrathin PMMA film served as both modification and buffering layer. [ABSTRACT FROM AUTHOR]

Highlights • CuPc/TIPS-pentacene bi-layer was used to enhance photo-OFET performance. • TIPS-pentacene sensed blue/green whereas CuPc sensed red/green color well. • Bi-layer devices showed ability to sense red/blue/green; all three colors. • Photo-responsivity of bi-layer was in between that for pristine layers. Abstract In this work, a combination of a thin layer of Copper (II) phthalocyanine (CuPc) and TIPS-pentacene crystal was used to enhance the photo-sensing spectrum of photo- sensitive organic field-effect transistors (photo-OFETs). In TIPS-pentacene/CuPc bi-layer devices, the different conduction path not only reduced the total number of traps but also enhanced the sensing spectrum. It was found that, though the TIPS-pentacene was able to sense only blue and green colour well, and CuPc was able to sense only red and green colour well; the TIPS-pentacene/CuPc bi-layer were able to sense all three colors, enhancing the range of sensing. On illumination, bi-layer TIPS-pentacene/CuPc OFETs exhibited higher values of shift in threshold voltage (| ΔV TH |) compared to neat TIPS-pentacene and bare CuPc OFETs, due to change in the spatial distribution in the trap state density and associated pattern of trapping of photo-generated charge carriers. It was also found that the values of photo-responsivity (R max) and photo-detection time for the bi-layer OFETs were in between that for OFETs with TIPS-pentacene or CuPc. [ABSTRACT FROM AUTHOR]

Abstract We report on the synthesis and characterization of a novel naphthalene diimide (NDI)-based small molecule with a bithiophene linker unit, NDI-BT-NDI-EH, for application as a solution-processable n -channel active material in organic field-effect transistors (OFETs). NDI-BT-NDI-EH was synthesized via the Stille coupling reaction and the bithiophene linker unit was introduced as a rotatable linker between two NDI cores to improve the solubility of NDI-BT-NDI-EH while maintaining its high field-effect mobility. We found that the crystallinity and molecular ordering of NDI-BT-NDI-EH thin films could be improved by thermal annealing; a moderate annealing temperature of 120 °C appeared to be optimal for promoting self-organization among the NDI-BT-NDI-EH molecules. The NDI-BT-NDI-EH molecules in thermally annealed thin films mainly adopted an edge-on orientation with improved π - π stacking on the surface of octyltrichlorosilane-treated SiO 2 substrates, which is favorable for lateral charge transport. As a result, the optimally annealed NDI-BT-NDI-EH OFET exhibited evident n -type OFET characteristics with high field-effect mobilities of up to 0.016 cm2 V−1 s−1 and an on/off ratio of 1.4 × 105. Graphical abstract Image 1 Highlights • A novel NDI-based organic small molecular semiconductor is synthesized via the Stille coupling reaction. • A rotatable bithiophene linker unit in NDI-BT-NDI-EH improves solubility while maintaining high carrier mobility. • Thermally annealed NDI-BT-NDI-EH molecules show an edge-on orientation with increased crystallinity. • NDI-BT-NDI-EH-based n -type OFETs exhibit high performance with μ e of up to 0.016 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]

Acenes/heteroacenes, the most widely studied small‐molecule organic semiconductors, always possess linear structures. In this work, three stable, soluble and angular π‐extended hepta‐thienoacenes with an internal carbazole, that is, thienobenzo‐fused carbazole (DTBCz) were synthesized via a four‐step tandem method. The tandem synthesis starting from carbazole derivatives led to interesting isomeric effects. The synthetic regioselectivity was discussed in detail. Their physical properties and electron density distributions were studied by UV/Vis absorption, photoluminescence, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), cyclic voltammetry (CV) measurements, and theoretical calculations. Their potentials as semiconducting materials were evaluated by fabricating the solution‐processed organic field‐effect transistors (OFETs). The more angular shaped isomer of DTB[32,34]Cz displayed the best performance with hole mobility up to 0.0044 cm2 V−1 s−1 in devices with a thickness of ca. 115 nm. Particularly, the performance of DTB[32,34]Cz‐based devices showed less dependence on the thickness of their active layer. Ace(ne)s up the sleeve: Angular shaped hepta‐thienoacenes with internal carbazole have been developed. Field‐effect hole mobility up to 4.4×10−3 cm2 V−1 s−1 and current on/off ratio=1.85×104 in air for DTB[32,34]Cz have been demonstrated in thick active layer devices with the top‐contact bottom‐gate FET device structures, representing an important step toward the solution‐processed OFET application of angular shaped acenes. [ABSTRACT FROM AUTHOR]

Abstract: Cocrystallization involving two or more components aggregating into cocrystals allows the preparation of materials with markedly improved charge mobility. This approach however, is little explored in all‐conjugated block copolymers (BCPs). Herein, we report the first investigation into the correlation between cocrystals and charge mobility in a series of new all‐conjugated BCPs: poly(3‐butylthiophene)‐b‐poly(3‐hexylselenophene) (P3BT‐b‐P3HS) for high‐performance field‐effect transistors. These rationally synthesized rod–rod BCPs self‐assemble into cocrystals with high charge mobilities. Upon one‐step thermal annealing, their charge mobilities decrease slightly despite their increased crystallinities. After two‐step thermal annealing, P3BT‐b‐P3HS (P3BT/P3HS=2:1) and (1:1) cocrystals disappear and phase separation occurs, leading to greatly decreased charge mobilities. In contrast, P3BT‐b‐P3HS (1:2) retains its cocrystalline structure and its charge mobility. [ABSTRACT FROM AUTHOR]

Abstract: Organic transistors with different structures are investigated to address the applicability and reliability of parameter extraction. A dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene channel is coupled with pristine or functionalized gold bottom and top contacts to reveal a geometrical impact on the device performance and nonidealities. Scanning Kelvin probe microscopy is employed as a key method to quantify the channel and contact potential in operation. Taking full account of the contact effects and including an explicit threshold voltage in calculation are shown to be critical to access the intrinsic carrier mobility, while simple derivative‐based extraction may over‐ or underestimate it. Further analytical developments correlate individual physical parameters, leading to the discovery that pentafluorobenzenethiol self‐assembled on gold predominantly affects the carrier mobility rather than the injection barrier. [ABSTRACT FROM AUTHOR]

Abstract: Two novel, donor–acceptor‐type π‐conjugated polymers (P1 and P2) with 3′‐(thieno[3,2‐b]thiophene‐2,5‐diylbis(methan‐1‐yl‐1‐ylidene))bis‐(indolin‐2‐one) (ITTI) as the acceptor and thiophene/bithiophene as the donor are designed and synthesized by palladium‐catalyzed Stille coupling. The optical and electrochemical properties of these polymers are characterized and further implemented into organic field‐effect transistors (OFET). Both polymers exhibit excellent thermal stability, broad UV–vis absorption, and high highest occupied molecular orbital energy levels. Thermal annealing induces a well‐ordered structure, a highly planar π‐system (oxygen–sulfur interaction), and a bathochromic shift in the polymers; furthermore, significant enhancement of the long wavelength intensity is also observed. Both polymers exhibit p‐type charge transport behavior, with hole mobilities up to 0.51 cm2 V−1 s−1 for P1 and 0.65 cm2 V−1 s−1 for P2. This work demonstrates that ITTI can be a promising building block for the construction of donor–acceptor polymers with high‐performance OFETs. [ABSTRACT FROM AUTHOR]

Abstract: A pneumatic nozzle‐based printing technique that can control the crystallization of small molecule organic semiconductor thin films during deposition is reported. By tuning the printing speed and the substrate temperature, large‐sized organic crystals are grown along the printing direction, resulting in field‐effect mobility enhancement by 50 times compared to spin‐coated films for 6,13‐bis(triisopropylsilylethynyl)‐pentacene. Furthermore, silver electrodes using the technique to fabricate printed flexible inverters with a gain as high as 16 are printed. [ABSTRACT FROM AUTHOR]

Poly(quinacridone-quinoxaline) (PQCQx) was synthesized to investigate the potential of quinacridone derivatives as organic semiconductors in organic field-effect transistors (OFETs) and circuits. The device showed a field-effect mobility value of 1.4 × 10 −3 cm 2 /(Vs) at optimal conditions. The morphologies of the deposited films were characterized by performing X-ray diffraction and atomic force microscopy. And, to confirm the feasibility of using PQCQx OFETs in a high-voltage logic circuit operation, a compact model library to describe the electrical behaviors of PQCQx OFETs was developed. By implementing the developed compact model library into a circuit simulator, we successfully evaluated the high-voltage-logic operation of a p-type organic inverter with a frequency of 45.5 kHz in an 80 V supply condition. [ABSTRACT FROM AUTHOR]

The copolymers P24DPP-silole and P29DPP-silole, each composed of diketopyrrolopyrrole (DPP) and silole derivatives, were synthesized using a Stille coupling reaction, and their electrical performances in organic field-effect transistors (OFETs) and circuits were investigated. While both the as-spun OFETs exhibited quite low field-effect hole mobility values, the OFETs subjected to thermal annealing at 150 °C exhibited typical ambipolar transport characteristics with average hole and electron mobility values of 1 × 10 −1 cm 2 /(V s) and 2 × 10 −3 cm 2 /(V s). Because the compact model was necessary to perform circuit design with the synthesized OFETs, a strategy for extracting compact model parameters was proposed for high-voltage logic circuit applications by using the industry standard compact Berkeley short-channel IGFET model (BSIM). [ABSTRACT FROM AUTHOR]

Herein is presented a comparative performance analysis of heterojunction organic-based light-emitting field-effect transistors (OLEFETs) with symmetric (Au only) and asymmetric (Au and LiF/Al) electrode contacts. The devices had a top source–drain contact with long-channel geometry and were produced by sequentially depositing p -type pentacene and n -type N,N ′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (P13) using a neutral cluster beam deposition apparatus. The spectroscopic, structural and morphological properties of the organic thin films were examined using photoluminescence (PL) spectroscopy, X-ray diffraction (XRD) method, laser scanning confocal and atomic force microscopy (LSCM, AFM). Based upon the growth of high-quality, well-packed crystalline thin films, the devices demonstrated ambipolar field-effect characteristics, stress-free operational stability, and light emission under ambient conditions. Various device parameters were derived from the fits of the observed characteristics. The hole mobilities were nearly equal irrespective of the electrode contacts, whereas the electron mobilities of the transistors with LiF/Al drain electrodes were higher due to the low injection barrier. For the OLEFETs with symmetric electrodes, electroluminescence (EL) occurred only in the vicinity of the hole-injecting electrode, whereas for the OLEFETs with asymmetric electrodes, the emission occurred in the vicinity of both hole- and electron-injecting electrodes. By tuning the carrier injection and transport through high- and low-work function metals, the hole-electron recombination sites could be controlled. The operating conduction and light emission mechanism are discussed with the aid of EL images obtained using a charge-coupled device (CCD) camera. [ABSTRACT FROM AUTHOR]

The critical role of the mixing ratio of the semiconductor and polymer solutions on the performance and electro-mechanical stability of the flexible blend OFETs is investigated. An improvement in the OFET performance was observed with increasing fraction of polymer in the solution. The maximum field-effect mobility improved from 0.08 for neat TIPS-pentacene OFETs to 0.24, 0.25 and 0.57 cm 2  V −1  s −1 for semiconductor:polymer blend OFETs with mixing ratio of 3:1, 1:1 and 1:3 respectively. Under stress conditions of V DS  =  V GS  = −5 V for 1 h, the 1:3 blend devices outperformed other categories of devices with very small drain current decay of ∼2% and 11% and small threshold voltage shift of 0.05 V and 0.27 V before and after 1.27% (R bend  = 5 mm) tensile strain application respectively. These devices also exhibited superior reliability with least performance spread over 100 continuous transfer characteristics measurement cycles before and after application of strain. [ABSTRACT FROM AUTHOR]

Herein, this study investigates the impact of branching-point-extended alkyl chains on the charge transport properties of three ultrahigh n-type mobility conjugated polymers. Using grazing incidence wide-angle X-ray scattering, analysis of the crystallinity of the series shows that while π-π interactions are increased for all three polymers as expected, the impact of the side-chain engineering on polymer backbone crystallinity is unique to each polymer and correlates to the observed changes in charge transport. With the three polymers exhibiting n-type mobilities between 0.63 and 1.04 cm2 V−1 s−1, these results ratify that the indolonaphthyridine building block has an unprecedented intrinsic ability to furnish high-performance n-type organic semiconductors. [ABSTRACT FROM AUTHOR]

Two novel platinum(II) donor-acceptor (D-A) naphthalene diimide (NDI)-based copolymers have been designed and synthesized. The effects of thiophene numbers on the thermal, optical, electronic and charge transport properties of the polymers have been investigated. These solution processable polymers exhibit p-channel field-effect charge transport characteristics, unlike other organic NDI-based polymeric analogues. All the results indicated that they have potential applications in high-performance organic field-effect transistors (OFETs). [ABSTRACT FROM AUTHOR]

Organic field-effect transistors (OFETs) were elaborated using N,N’-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C 13) as transport electron material and two polymeric insulators were used as gate dielectric: polymethyl methacrylate (PMMA), a low-k material widely used in OFETs, and poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)), a ferroelectric material that has a high relative permittivity. Several configurations using both dielectrics were studied. We report a threshold and operating voltage reduction by 3 and 2, respectively, with P(VDF-TrFE)/PMMA gate dielectric compared to PMMA reference OFETs due to a higher capacitance value. It exhibits good performances with a mobility of 0.165 cm ^2/V$\cdot$ s, a threshold voltage of 2.9 V, and an on–off current ratio >3\; \times \;10^{4}. [ABSTRACT FROM PUBLISHER]

The heterocyclic thiazole unit has been extensively used as electron-deficient building block in π-conjugated materials over the last decade. Its incorporation into organic semiconducting materials is particularly interesting due to its structural resemblance to the more commonly used thiophene building block, thus allowing the optoelectronic properties of a material to be tuned without significantly perturbing its molecular structure. Here, we discuss the structural differences between thiazole- and thiophene-based organic semiconductors, and the effects on the physical properties of the materials. An overview of thiazole-based polymers is provided, which have emerged over the past decade for organic electronic applications and it is discussed how the incorporation of thiazole has affected the device performance of organic solar cells and organic field-effect transistors. Finally, in conclusion, an outlook is presented on how thiazole-based polymers can be incorporated into all-electron deficient polymers in order to obtain high-performance acceptor polymers for use in bulk-heterojunction solar cells and as organic field-effect transistors. Computational methods are used to discuss some newly designed acceptor building blocks that have the potential to be polymerized with a fused bithiazole moiety, hence propelling the advancement of air-stable n-type organic semiconductors. [ABSTRACT FROM AUTHOR]

The selective and rapid detection of trace amounts of highly toxic chemical warfare agents has become imperative for efficiently using military and civilian defense. Metal-organic frameworks (MOFs) are a class of inorganic-organic hybrid porous material that could be potential next-generation toxic gas sensors. However, the growth of a MOF thin film for efficiently utilizing the material properties for fabricating electronic devices has been challenging. Herein, we report a new approach to efficiently integrate MOF as a receptor through diffusion-induced ingress into the grain boundaries of the pentacene semiconducting film in the place of the most adaptive chemical functionalization method for sensor fabrication. We used bilayer conducting channel-based organic field-effect transistors (OFETs) as a sensing platform comprising CPO-27-Ni as the sensing layer, coated on the pentacene layer, showed a strong response toward sensing of diethyl sulfide, which is one of the stimulants of bis (2-chloroethyl) sulfide, a highly toxic sulfur mustard (HD). Using OFET as a sensing platform, these sensors can be a potential candidate for trace amounts of sulfur mustard detection below 10 ppm in real time as wearable devices for onsite uses.

High-performance solution processed flexible organic field-effect transistors with 6,13(bis-triisopropylsily-lethynyl) pentacene and polystyrene blend are demonstrated with high electro-mechanical stability. For −5 V operation, field-effect mobility up to 1.1 cm ^2~\textV^\mathrm -1~\texts^\mathrm -1 and threshold voltage as low as −0.1 V were obtained with high current on–off ratios of \sim 10^5 due to high quality dielectric–semiconductor interface developed during solvent evaporation. Stable electrical characteristics were achieved with increasing duration of mechanical strain, and after multiple cycles of tensile and compressive strain. Drain current decay of 10%, very large trapping time of \sim 10^8 s, and a very small threshold voltage shift of 0.3 V were observed during bias stress of 1 h, signifying low charge carrier trapping and a high quality of dielectric–semiconductor interface, which was retained largely after two days of continuous tensile strain. Moreover, after 100 cycles of tensile and compressive strain, the corresponding shift in threshold voltage due to bias stress was still $\sim 0.5$ V. Overall, a high performance and stability were demonstrated under collective effects of mechanical and electrical stress. [ABSTRACT FROM PUBLISHER]

Epitaxial crystallization of perylo[1,12- b , c , d ]selenophene (PESE) on highly oriented polyethylene (PE) substrate through vapor phase deposition has been achieved. Oriented PESE crystals with different crystalline morphologies can be fabricated by changing the temperature of PE substrate during vacuum evaporation. When the PE substrate temperature is lower than 70 °C, sparsely dispersed PESE lathlike crystals are produced with their long axis preferentially aligned perpendicular to the chain direction of PE crystals. While the close films of PESE with lathlike crystals aligned with long axis parallel to the chain direction of PE film were obtained above 90 °C. Transistors based on expitaxially crystallized PESE films have been fabricated and the transistor properties were also studied. It is found that transistors show different electrical characteristics depending on the preparation conditions of expitaxially crystallized PESE films. The transistors based on the PESE/PE-SiO 2 /Si with PESE deposited on oriented PE film at low temperature, i.e., <70 °C, display a similar poor properties with the PESE/OTS-SiO 2 /Si type transistors. However, when the deposition temperature was elevated to 90 °C, the transistors exhibit a maximum field-effect mobility of 4.4 × 10 −2 cm 2 V −1 s −1 and maximum on/off ratio of 2.0 × 10 5 , which are about 2 orders of magnitudes higher than the PESE/OTS-SiO 2 /Si based transistors. [ABSTRACT FROM AUTHOR]

Flexible organic field-effect transistors (OFETs) with TIPS-pentacene: polystyrene (PS) blend are demonstrated to exhibit enhanced mobility and significantly improved electrical stability compared to neat TIPS-pentacene on poly(4-vinylphenol) (PVP) dielectric (bi-layer OFETs), along with high mechanical stability. Due to merit of high quality dielectric-semiconductor interface, pristine TIPS-pentacene: PS blend OFETs exhibited maximum mobility of 0.93 cm 2 V −1 s −1 with average of 0.44(±0.25) cm 2 V −1 s −1 compared to 0.14(±0.10) cm 2 V −1 s −1 for bi-layer OFETs with high current on-off ratios on the order 10 5 for both. Both types of devices exhibited high electrical stability upon bending with increasing magnitude of strain or its duration up to 5 days. However, significant differences in electrical stability of devices were observed upon applying constant bias-stress for 40 min to 1 h. Pristine blend devices exhibited outstanding electrical stability with very low drain current decay of <5% compared to ∼30% for bi-layer devices. Even upon bias-stress after 5 days of bending, the drain current decay levels were only changed to <10% and ∼50% for blend and bi-layer devices respectively. [ABSTRACT FROM AUTHOR]

To investigate the origins of hydroxyl groups in a polymeric dielectric and its applications in organic field-effect transistors (OFETs), a polar polymer layer was inserted between two polymethyl methacrylate (PMMA) dielectric layers, and its effect on the performance as an organic field-effect transistor (OFET) was studied. The OFETs with a sandwiched dielectric layer of poly(vinyl alcohol) (PVA) or poly(4-vinylphenol) (PVP) containing hydroxyl groups had shown enhanced characteristics compared to those with only PMMA layers. The field-effect mobility had been raised more than 10 times in n-type devices (three times in the p-type one), and the threshold voltage had been lowered almost eight times in p-type devices (two times in the n-type). The on-off ratio of two kinds of devices had been enhanced by almost two orders of magnitude. This was attributed to the orientation of hydroxyl groups from disordered to perpendicular to the substrate under gate-applied voltage bias, and additional charges would be induced by this polarization at the interface between the semiconductor and dielectrics, contributing to the accumulation of charge transfer. [ABSTRACT FROM AUTHOR]

Solution-processed dielectric materials with a high dielectric constant ( k ) have attracted considerable attention due to their potential applications in low-voltage-operating organic field-effect transistors (OFETs) for realizing large-area and low-power electronic devices. In terms of device commercialization, the patterning of each film component via a facile route is an important issue. In this study, we introduce a photo-patternable precursor, zirconium acrylate (ZrA), to fabricate photo-patterned high- k zirconium oxide (ZrO x ) dielectric layers with UV light. Solution-processed ZrA films were effectively micro-patterned with UV exposure and developing, and transitioned to ZrO x through a sol-gel reaction during deep-UV annealing. The UV-assisted and ∼10 nm-thick ZrO x dielectric films exhibited a high capacitance (917.13 nF/cm 2 at 1 KHz) and low leakage current density (10 −7 A/cm 2 at 1.94 MV/cm). Those films could be utilized as gate dielectric layers of OFETs after surface modification with ultrathin cyclic olefin copolymer layers. Finally, we successfully fabricated organic complementary inverters exhibiting hysteresis-free operation and high voltage gains of over 42 at low voltages of ≤3 V. [ABSTRACT FROM AUTHOR]