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The semiconductor/insulator blends for organic field-effect transistors are a potential solution to improve the charge transport in the active layer by inducing phase separation in the blends. However, the technique is less investigated for long-chain conducting polymers such as Poly[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno [3,2-b]thiophene)] (DPPDTT), and lateral phase separation is generally reported due to the instability during solvent evaporation, which results in degraded device performance. Herein, we report how to tailor the dominant mechanism of phase separation in such blends and the molecular assembly of the polymer. For DPPDTT/PMMA blends, we found that for higher DPPDTT concentrations (more than 75%) where the vertical phase separation mechanism is dominant, PMMA assisted in the self-assembly of DPPDTT to form nanowires and micro-transport channels on top of PMMA. The formation of nanowires yielded 13 times higher mobility as compared to pristine devices. For blend ratios with DPPDTT ≤ 50%, both the competing mechanisms, vertical and lateral phase separation, are taking place. It resulted in somewhat lower charge carrier mobilities. Hence, our results show that by systematic tuning of the blend ratio, PMMA can act as an excellent binding material in long-chain polymers such as DPPDTT and produce vertically stratified and aligned structures to ensure high mobility devices. [ABSTRACT FROM AUTHOR]

The delafossite semiconductor CuInO 2 has shown great potential in transparent electronics for its bipolar dopability. However, little is known about the limiting factors about its carrier mobility, which impedes its further development. Applying a b i n i t i o Boltzmann transport formalism, here we calculate the intrinsic, phonon-limited carrier mobility of CuInO 2 and study its carrier–phonon coupling mechanisms. The calculated room-temperature electron and hole mobilities along the in-plane direction are μ e = 97.6 cm 2 V − 1 s − 1 and μ h = 1.4 cm 2 V − 1 s − 1 , respectively. We find that the electron mobility is limited by the combination of acoustic phonons and polar longitudinal optical (LO) phonons, while the hole mobility is mainly limited by carrier–acoustic phonon scattering. We further show that the electron effective mass and bandgap of CuInO 2 can be tuned through strain engineering for improved carrier transport properties. Our work uncovers the underlying factors that govern the intrinsic carrier mobility of the transparent bipolar semiconductor CuInO 2 and sheds light on the design and exploration of bipolar conducting transparent conductive oxides (TCOs) based on delafossite semiconductors. [ABSTRACT FROM AUTHOR]

Designing organic semiconductors for practical applications in organic solar cells, organic field-effect transistors, and organic light-emitting diodes requires understanding charge transfer mechanisms across different length and time scales. The underlying electron transfer mechanisms can be efficiently explored using semiempirical quantum mechanical (SQM) methods. The dimer projection (DIPRO) method combined with the recently introduced non-self-consistent density matrix tight-binding potential (PTB) [Grimme et al., J. Chem. Phys. 158, 124111 (2023)] is used in this study to evaluate charge transfer integrals important for understanding charge transport mechanisms. PTB, parameterized for the entire Periodic Table up to Z = 86, incorporates approximate non-local exchange, allowing for efficient and accurate calculations for large hetero-organic compounds. Benchmarking against established databases, such as Blumberger's HAB sets, or our newly introduced JAB69 set and comparing with high-level reference data from ωB97X-D4 calculations confirm that DIPRO@PTB consistently performs well among the tested SQM approaches for calculating coupling integrals. DIPRO@PTB yields reasonably accurate results at low computational cost, making it suitable for screening purposes and applications to large systems, such as metal-organic frameworks and cyanine-based molecular aggregates further discussed in this work. [ABSTRACT FROM AUTHOR]

Using Bayesian spectroscopy, we performed spectral decomposition of gate modulation (GM) spectra measured in a pentacene organic field-effect transistor to understand comprehensively the optical nonlinear response due to GM and hole injection. Although GM spectra contain a variety of spectral components, by Bayesian spectroscopy, we can specify the role of each component in the nonlinear response by performing model selection that chooses the spectral components needed to explain the data without preconceptions. For a GM spectrum under positive GM, Bayesian spectroscopy shows that nonlinear responses by the change in polarizability dominate the GM spectrum among several types of Stark signals induced by the GM electric field, which is a physically valid conclusion. For GM spectra under negative GM where gate-induced carriers are injected, Bayesian spectroscopy succeeds in completely elucidating the spectral structure, which is composed of the two types of Stark signals due to changes in the polarizability and the dipole moment, bleaching, and gate-induced absorption signals. A pentacene film is known to have solid and isolated molecular phases, which may give different spectral responses. Therefore, we compared a model that treats these responses equally and a model that distinguishes them. Bayesian spectroscopy selects the latter models for all GM spectra, revealing statistically that nonlinear optical effects and hole injection effects are different in these phases. [ABSTRACT FROM AUTHOR]

Demonstration of acoustically improving charge transport characteristics of regioregular poly(3-hexylthiophene) (rrP3HT) based organic field effect transistor (OFET) fabricated on YZ lithium niobate piezoelectric substrate has been presented and analyzed. Owing to the acoustoelectric (AE) effect, a surface acoustic wave (SAW) propagating through the substrate transfers its momentum and energy to the charges in the rrP3HT channel, reducing the effective energy gap between the charge hopping states, which leads to a decrease in charge trapping and an increase in path conductivity and number of paths for charge transport. Hence, a significant increase in drain current and mobility and a substantial reduction in gate voltage were observed in the presence of SAW. The AE effect has been especially predominant in devices with smaller channel width, depicting that gate voltage brought down by 30 V provided drain current equivalent to that obtained in the absence of SAW. The bias stress analysis of the devices showed an increase in current instead of the decrease, generally seen with respect to time, reinforcing that the long term charge trapping effect in OFETs can be compensated with the propagation of SAW leading to enhanced device stability. [ABSTRACT FROM AUTHOR]

Epitaxial graphene (EG) on cubic silicon carbide (3C-SiC) on silicon holds the promise of tunable nanoelectronic and nanophotonic devices, some uniquely unlocked by the graphene/cubic silicon carbide combination, directly integrated with the current well-established silicon technologies. Yet, the development of graphene field-effect devices based on the 3C-SiC/Si substrate system has been historically hindered by poor graphene quality and coverage, as well as substantial leakage issues of the heteroepitaxial system. We address these issues by growing EG on 3C-SiC on highly resistive silicon substrates using an alloy-mediated approach. In this work, we demonstrate a field-effect transistor based on EG/3C-SiC/Si with gate leakage current 6 orders of magnitude lower than the drain current at room temperature, which is a vast improvement on the current literature, opening the possibility for dynamically tunable nanoelectronic and nanophotonic devices on silicon at the wafer level. [ABSTRACT FROM AUTHOR]

Chemical doping is a powerful way to enhance the electrical performance of organic electronics. To avoid perturbing the ordered molecular packing of organic semiconducting hosts, molecular dopants are deposited on the surface of highly crystalline organic semiconductor thin films. However, such surface doping protocols not only limit charge‐transfer efficiency but also cause dopant diffusion problems, which significantly reduce charge carrier mobility and device stability. Here, an innovative anion bulk doping strategy is reported that allows effective doping of organic single‐crystalline films (OSCFs) without disrupting molecular ordering to improve the performance of organic field‐effect transistors (OFETs). This method is mediated by anion dopants and can be pictured as an effective charge transfer of dopants with organic semiconductors in liquid phase. The direct introduction of dopant anions overcomes limitations of partial charge transfer while avoiding interference from dopant aggregation with crystallization. Using this method, the average carrier mobility of the OSCFs is boosted by ≈2.5 times. Significantly, low‐voltage OFETs developed from anion‐doped OSCFs exhibit a near‐ideal subthreshold swing of 59.2 mV dec−1 and unparalleled mobility as high as 19.8 cm2 V−1 s−1 together with excellent stability. The concept of anion doping opens new avenues for improving the electrical performance of organic electronics. [ABSTRACT FROM AUTHOR]

A series of novel discotic liquid-crystalline donor–acceptor (D–A) dyads 5D10An (n = 4, 5, 6, 7, 8) adjusted by changing the chain length (n) of diester groups on perylene were synthesized based on triphenylene and perylene units, which were linked by a flexible linkage of 10-decyloxy-1-amine. Results from differential scanning calorimetry (DSC), one-dimensional X-ray diffraction (XRD) patterns, and polarized optical microscopy (POM) images indicate that 5D10A4, 5D10A5, 5D10A6, and 5D10A7 exhibited hexagonal columnar phase at high temperature ranges and rectangular columnar phases at room temperature. Combining the XRD data and the steady state spectra of UV-Vis and fluorescence spectroscopy, the intramolecular triphenylenes and perylene diester cores were stacked separately in distinct columns and nano-segregation occurred during self-assembly. The HOMO/LUMO energy levels were obtained using CV, UV-Vis spectroscopy, UPS and Gaussian09. Charge carrier mobilities were measured by a time-of-flight (TOF) device. These discotic liquid-crystalline compounds exhibited highly efficient ambipolar charge-transport properties, and the hole and electron mobilities can reach the order of 10−3 cm2 V−1 s−1 by segregated D–A columns. This is the first report on D–A dyads' discotic liquid crystals, which not only feature ambipolar transport but also exhibit columnar phase structures that can be stabilized at room temperature, providing potential utility of the strategy in organic optoelectronic applications. [ABSTRACT FROM AUTHOR]

Over the past decade, molecular‐switch‐embedded memory devices, particularly field‐effect transistors (FETs), have gained significant interest. Molecular switches are integrated to regulate the resistance or current levels in FETs. Despite substantial efforts, realizing large memory window with a long retention time, a critical factor in memory device functionality, remains a challenge. This is due to the inability of an isomeric state of a molecular switch to serve as a stable deep trap state within the semiconductor layer. Herein, the study addresses this limitation by introducing chemical bonding between molecular switch and conjugated polymeric semiconductor, facilitating closed isomer of diarylethene (DAE) to operate as a morphologically stable deep trap state. Azide‐ and diazirine‐anchored DAEs are synthesized, which form chemical bonds to the polymer through photocrosslinking, thereby implementing permanent and controllable trapping states nearby conjugated backbone of polymer semiconductor. Consequently, when diazirine‐anchored DAE is blended with F8T2 and subjected to photocrosslinking, the resulting organic FETs exhibit remarkable memory performance, including a memory window of 22 V with a retention time over 106 s, a high photoprogrammable on/off ratio over 103, and a high operational stability over 100 photocycles. Further, photophore‐anchored DAEs can achieve precise patterning, which enables meticulous control over the semiconductor layer structure. [ABSTRACT FROM AUTHOR]

Contact resistance has become one of the main bottlenecks that hinder further improvement of mobility and integration density of organic field‐effect transistors (OFETs). Much progress has been made in reducing contact resistance by modifying the electrode/semiconductor interface and decreasing the crystal thickness, however, the development of new organic semiconductor materials with low contact resistance still faces many challenges. Here, 2,6‐bis‐phenylethynyl‐anthracene (BPEA) is found, which is a material that combines high mobility with low contact resistance. Single‐crystal BEPA OFETs with a thickness of ≈20 nm demonstrated high mobility of 4.52 cm2 V−1 s−1, contact resistance as low as 335 Ω cm, and band‐like charge transport behavior. The calculated compatibility of the EHOMO of BPEA with the work function of the Au electrode, and the decreased |EHOMO‐ΦAu| with the increase of external electric field intensity from source to gate both contributed to the efficient charge injection and small contact resistance. More intriguingly, p‐type BPEA as a buffer layer can effectively reduce the contact resistance, improve the mobility, and meanwhile inhibit the double‐slope electrical behavior of p‐channel 2,6‐diphenyl anthracene (DPA) single‐crystal OFETs. [ABSTRACT FROM AUTHOR]

High-performance organic devices with dynamic and stable modulation are essential for building devices adaptable to the environment. However, the existing reported devices incorporating light-activated units exhibit either limited device stability or subpar optoelectronic properties. Here, we synthesize a new optically tunable polymer dielectric functionalized with photochromic arylazopyrazole units with a cis-isomer half-life of as long as 90 days. On this basis, stable dual-mode organic transistors that can be reversibly modulated are successfully fabricated. The trans-state devices exhibit high carrier mobility reaching 7.4 square centimeters per volt per second and excellent optical figures of merit, whereas the cis-state devices demonstrate stable but starkly different optoelectronic performance. Furthermore, optical image sensors are prepared with regulatable nonvolatile memories from 36 hours (cis state) to 108 hours (trans state). The achievement of dynamic light modulation shows remarkable prospects for the intelligent application of organic optoelectronic devices. [ABSTRACT FROM AUTHOR]

Sub‐monolayer networks of the electron‐transporting semiconducting polymer poly([N,N'‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)−2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)) (P(NDI2OD‐T2)) are realized through judicious choice of spin‐coating solvent and control of solution concentration. These sub‐monolayer networks provide a platform to study the effects of surface coverage, network connectivity, and orientational order on charge transport. It is found that charge transport through semiconducting polymer networks depends not only on the coverage/concentration of the material but also on the nature of the conduction paths themselves. Down to 40% surface coverage, current measured in a field‐effect architecture decreases in line with the decrease in surface coverage, but drops precipitously below a surface coverage of 40%. Below 40% surface coverage, there is a marked decrease in network connectivity (quantified through the branching point density) and a decrease in orientational order. Furthermore, an increase in the density of dangling branches (dead ends) is also seen with decreasing surface coverage. Additional supporting data in the form of grazing incidence wide‐angle X‐ray scattering (GIWAXS), optical spectroscopy, and charge modulation spectroscopy are presented, which help to establish that long‐range interconnectivity rather than local morphology dominates charge transport in P(NDI2OD‐T2) sub‐monolayers as well as thin films. [ABSTRACT FROM AUTHOR]

Merging the functionality of an organic field-effect transistor (OFET) with either a light emission or a photoelectric effect can increase the efficiency of displays or photosensing devices. In this work, we show that an organic semiconductor enables a multifunctional OFET combining electroluminescence (EL) and a photoelectric effect. Specifically, our computational and experimental investigations of a six-ring thiophene-phenylene co-oligomer (TPCO) revealed that this material is promising for OFETs, light-emitting, and photoelectric devices because of the large oscillator strength of the lowest-energy singlet transition, efficient luminescence, pronounced delocalization of the excited state, and balanced charge transport. The fabricated OFETs showed a photoelectric response for wavelengths shorter than 530 nm and simultaneously EL in the transistor channel, with a maximum at ~570 nm. The devices demonstrated an EL external quantum efficiency (EQE) of ~1.4% and a photoelectric responsivity of ~0.7 A W–1, which are among the best values reported for state-of-the-art organic light-emitting transistors and phototransistors, respectively. We anticipate that our results will stimulate the design of efficient materials for multifunctional organic optoelectronic devices and expand the potential applications of organic (opto)electronics. [ABSTRACT FROM AUTHOR]

Solid‐state molecular arrangement has been recognized as the most important role in the charge transport properties of organic semiconductors. Although highly ordered molecular stacking is achieved in single crystals, maintaining single‐crystal molecular packing in solution‐processed thin films remains a significant challenge. Herein, a new type of n‐type organic semiconductors based on an asymmetric fluoranthene imide unit is reported, whose intermolecular packing and aggregation behavior in the thin film state can be effectively controlled by regulating the cyano substitution sites and alkyl chain types in the imide group. F10 with cyano groups at 4,9‐sites and branched 2‐ethylhexyl chain encouragingly shows a highly ordered single‐crystal‐like molecular packing in solution‐processed thin film after thermal annealing, and thus the resulting organic field‐effect transistors exhibit impressive charge transport performance, with the electron mobility as high as 0.116 cm2 V−1 s−1. This work opens a new avenue for developing high‐performance solution‐processed n‐type semiconductors. [ABSTRACT FROM AUTHOR]

The imperative for continuous device miniaturization has heightened the need for logic reconfigurability due to its benefits in circuit design simplification and process optimization. Van der Waals ambipolar transistors, notable for their inherent reconfigurable characteristics, have garnered significant interest for their potential to revolutionize information electronics. Nevertheless, as the semiconductor thickness approaches the 3-nm mark, precise modulation of electrical polarity presents a considerable challenge as minor variations in thickness can lead to significant electrical disparities. Here, we introduce a silicon backend process-compatible approach by employing surface charge transfer doping to skillfully adjust the polarity in ambipolar transistors. This universal method can achieve a controllable p-type doping effect and good electrical symmetry in ambipolar semiconductors. Through careful calibration of the MoO3 dopant layer thickness, we significantly enhance the hole mobility in doped WSe2 field-effect transistors (FETs), increasing it from 8 to 100 cm2 V−1 s−1, surpassing the performance of most non-silicon p-type semiconductors. A thorough temperature-dependent doping characterization elucidates the deeper traps-induced Schottky barrier variation for hole transport, and a reduction in current fluctuation for electron transport in WSe2/MoO3 FETs. Leveraging the precision in electrical polarity control, we demonstrate a complementary logic inverter by integrating two doped ambipolar FETs on a single monolithic channel. This advancement paves the way for quasi-forksheet structures and underscores the benefits in evolving advanced processing technologies, steering toward scalable, cost-effective, and efficient electronic device fabrication. [ABSTRACT FROM AUTHOR]

In organic field‐effect transistors (OFETs) using disordered organic semiconductors, interface traps that hinder efficient charge transport, stability, and device performance are inevitable. Benchmark poly(9,9‐dioctylfuorene‐co‐bithiophene) (F8T2) liquid‐crystalline polymer semiconductor has been extensively investigated for organic electronic devices due to its promising combination of charge transport and light emission properties. This study demonstrates that high‐capacitance single‐layered ionic polyurethane (PU) dielectrics enable enhanced charge transport in F8T2 OFETs. The ionic PU dielectrics are composed of a mild blending of PU ionogel and PU solution, thereby forming a solid‐state film with robust interfacial characteristics with semiconductor layer and gate electrode in OFETs and measuring high capacitance values above 10 µF cm−2 owing to the combined dipole polarization and electric double layer formation. The optimized fabricated ionic PU‐gated OFETs exhibit a low‐voltage operation at −3 V with a remarkable hole mobility of over 5 cm2 V–1 s–1 (average = 2.50 ± 1.18 cm2 V–1 s–1), which is the highest mobility achieved so far for liquid‐crystalline F8T2 OFETs. This device also provides excellent bias‐stable characteristics in ambient air, exhibiting a negligible threshold voltage shift of −0.03 V in the transfer curves after extended bias stress, with a reduced trap density. [ABSTRACT FROM AUTHOR]

Meniscus‐guided coating (MGC) is a promising method that offers predictable fabrication of highly crystalline thin films. For the integration of molecular semiconductors into large‐area electronic devices with high efficiency and reliability, homogeneous and highly ordered film morphologies are required. The solution processing of such defect‐free film structures requires comprehensive understanding of the complex relationship between molecular crystallization, fluid dynamics, and meniscus shape. In this work, the role of the meniscus shape on fluid dynamics in the coating bead and the crystallization process of the low molecular weight semiconductor 6,13‐bis(triisopropylsilylethynyl)pentacene (TIPS‐pentacene) during zone‐casting is systematically investigated. Depending on meniscus shape and coating velocity, four morphological subregimes are found: stick‐slip morphology, unidirectional homogenous crystal stripes, spherulitic morphology, and directional branched morphology; of which the second exhibits the highest crystallinity with a reduced trap density in the thin film, resulting in improved saturation and effective mobilities in field‐effect transistors (FET). Numerical simulation of fluid dynamics explains the observed morphological trends, which are correlated with the electrical behavior of the devices. This work provides a fundamental basis for upscaling MGC methods for the application of functional thin films. [ABSTRACT FROM AUTHOR]

Organic photoelectric neuromorphic devices that mimic the brain are widely explored for advanced perceptual computing. However, current individual neuromorphic synaptic devices mainly focus on utilizing linear models to process optoelectronic signals, which means that there is a lack of effective response to nonlinear structural information from the real world, severely limiting the computational efficiency and adaptability of networks to static and dynamic information. Here, a feedforward photoadaptive organic neuromorphic transistor with mixed‐weight plasticity is reported. By introducing the potential of the space charge to couple gate potential, photoexcitation, and photoinhibition occur successively in the channel under the interference of constant light intensity, which enables the device to transform from a linear model to a nonlinear model. As a result, the device exhibits a dynamic range of over 100 dB, exceeding the currently reported similar neuromorphic synaptic devices. Further, the device achieves adaptive tone mapping within 5 s for static information and achieves over 90% robustness recognition accuracy for dynamic information. Therefore, this work provides a new strategy for developing advanced neuromorphic devices and has great potential in the fields of intelligent driving and brain‐like computing. [ABSTRACT FROM AUTHOR]

The field-effect transistor (FET) is a fundamental component of semiconductors and the electronic industry. High on-current and mobility with layer-dependent features are required for outstanding FET channel material. Two-dimensional materials are advantageous over bulk materials owing to their higher mobility, high ON/OFF ratio, low tunneling current, and leakage problems. Moreover, two-dimensional heterostructures provide a better way to tune electrical properties. In this work, the two distinct possibilities of PdSe2/MoSe2 heterostructure have been employed through mechanical exfoliation and analyzed their electrical response. These diffe approaches to heterostructure formation serve as crucial components of our investigation, allowing us to explore and evaluate the unique electronic properties arising from each design. This work demonstrates that the heterostructure possesses a better ON/OFF ratio of ∼5.78 × 105, essential in switching characteristics. Moreover, MoSe2 provides a defect-free interface to PdSe2, resulting in a higher ON current of ∼10 μ A and mobility of ∼63.7 cm2V−1s−1, necessary for transistor applications. In addition, comprehending the process of charge transfer occurring at the interface between transition metal dichalcogenides is fundamental for advancing next-generation technologies. This work provides insights into the interface formed between the PdSe2 and MoSe2 that can be harnessed in transistor applications. [ABSTRACT FROM AUTHOR]

Gas detection is crucial for detecting environmentally harmful gases. Organic field-effect transistor (OFET)-based gas sensors have attracted attention due to their promising performance and potential for integration into flexible and wearable devices. This review examines the operating mechanisms of OFET-based gas sensors and explores methods for improving sensitivity, with a focus on porous structures. Researchers have achieved significant enhancements in sensor performance by controlling the thickness and free volume of the organic semiconductor layer. Additionally, innovative fabrication techniques like self-assembly and etching have been used to create porous structures, facilitating the diffusion of target gas molecules, and improving sensor response and recovery. These advancements in porous structure fabrication suggest a promising future for OFET-based gas sensors, offering increased sensitivity and selectivity across various applications. [ABSTRACT FROM AUTHOR]

The optoelectronic properties of semiconducting polymers and device performance rely on a delicate interplay of design and processing conditions. However, screening and optimizing the relationships between these parameters for reliably fabricating organic electronics can be an arduous task requiring significant time and resources. To overcome this challenge, Polybot is developed—a robotic platform within a self‐driving lab that can efficiently produce organic field‐effect transistors (OFETs) from various semiconducting polymers via high‐throughput blade coating deposition. Polybot not only handles the fabrication process but also can conduct characterization tests on the devices and autonomously analyze the data gathered, thus facilitating the rapid acquisition of data on a large scale. This work leverages the capabilities of this platform to investigate the fabrication of OFETs using hydrogen bonding‐containing semiconducting polymers. Through high‐throughput fabrication and characterization, various data trends are analyzed, and large extents of anisotropic charge mobility are observed in devices. The materials are thoroughly characterized to understand the role of processing conditions in solid state and electronic properties of these organic semiconductors. The findings demonstrate the effectiveness of automated fabrication and characterization platforms in uncovering novel structure–property relationships, facilitating refinement of rational chemical design, and processing conditions, ultimately leading to new semiconducting materials. [ABSTRACT FROM AUTHOR]

The assembly of functional materials into microstructures, which extends unique features such as enlarged specific surface areas, effective conduction paths, higher material utilization ratios, and ordered alignment compared to continuous films, has gained prominence in various fields. Achieving high performance in electronics requires cooperation among building blocks, fabrication methods, and device design. However, the remaining challenge is obtaining highly regular and large-scale patterns with controllable assembly methods while maximizing device performances. Manipulating functional materials with liquid assistance is a feasible approach to realizing controllable dewetting, regular molecule packing, and customized performances. This review focuses on the recent advances in preparing and applying liquid-induced microstructures. The predominant preparation technologies are summarized, including flow-enabled assembly, nanoimprint lithography, and capillary-bridge-mediated assembly. Furthermore, diverse applications of various microstructure-based electronics, such as flexible and transparent electrodes, organic field-effect transistors, gas sensors, photodetectors, and solar cells, are demonstrated. [ABSTRACT FROM AUTHOR]

Organic electrochemical transistors (OECTs) rely on both efficient ionic doping/de‐doping process and carrier transport in the mixed ionic‐electronic channel under the modulation of gate bias. Moreover, channels that hold photopatterning capability are highly desired to minimize parasitic capacitance and simplify the fabrication process/cost. However, yielding photo‐patternable channels with both precise/robust patterning capability and controllable ionic‐electronic coupling is still challenging. Herein, double‐end trifluoromethyl diazirines (DtFDA) with different chain lengths are introduced in the OECT channel to act as both photo‐crosslinker and medium to regulate ionic‐electronic transport. Specifically, high‐resolution patterns with a minimum line width/gap of 2 μm are realized in p(g2T‐T) or Homo‐gDPP based channels by introducing DtFDA. Maximum transconductances of 68.6 mS and 81.6 mS, current on/off ratio of 106 and 107 (under a drain voltage of only ±0.1 V), are achieved in p‐ and n‐type vertical OECTs (vOECTs), respectively, along with current densities exceeding 1 kA cm−2 and good cycling stability of more than 100,000 cycles (2000 seconds). This work provides a new and facile strategy for the fabrication of vOECT channels with high resolution and high performance via the introduction of a simple and efficient crosslinker. [ABSTRACT FROM AUTHOR]

Organic electrochemical transistors (OECTs) rely on both efficient ionic doping/de‐doping process and carrier transport in the mixed ionic‐electronic channel under the modulation of gate bias. Moreover, channels that hold photopatterning capability are highly desired to minimize parasitic capacitance and simplify the fabrication process/cost. However, yielding photo‐patternable channels with both precise/robust patterning capability and controllable ionic‐electronic coupling is still challenging. Herein, double‐end trifluoromethyl diazirines (DtFDA) with different chain lengths are introduced in the OECT channel to act as both photo‐crosslinker and medium to regulate ionic‐electronic transport. Specifically, high‐resolution patterns with a minimum line width/gap of 2 μm are realized in p(g2T‐T) or Homo‐gDPP based channels by introducing DtFDA. Maximum transconductances of 68.6 mS and 81.6 mS, current on/off ratio of 106 and 107 (under a drain voltage of only ±0.1 V), are achieved in p‐ and n‐type vertical OECTs (vOECTs), respectively, along with current densities exceeding 1 kA cm−2 and good cycling stability of more than 100,000 cycles (2000 seconds). This work provides a new and facile strategy for the fabrication of vOECT channels with high resolution and high performance via the introduction of a simple and efficient crosslinker. [ABSTRACT FROM AUTHOR]

Continuous glucose monitoring systems (CGMs) are critical toward closed-loop diabetes management. The field's progress urges next-generation CGMs with enhanced antinoise ability, reliability, and wearability. Here, we propose a coin-sized, fully integrated, and wearable CGM, achieved by holistically synergizing state-of-the-art interdisciplinary technologies of biosensors, minimally invasive tools, and hydrogels. The proposed CGM consists of three major parts: (i) an emerging biochemical signal amplifier, the organic electrochemical transistor (OECT), improving the signal-to-noise ratio (SNR) beyond traditional electrochemical sensors; (ii) a microneedle array to facilitate subcutaneous glucose sampling with minimized pain; and (iii) a soft hydrogel to stabilize the skin-device interface. Compared to conventional CGMs, the OECT-CGM offers a high antinoise ability, tunable sensitivity and resolution, and comfort wearability, enabling personalized glucose sensing for future precision diabetes health care. Last, we discuss how OECT technology can help push the limit of detection of current wearable electrochemical biosensors, especially when operating in complicated conditions. [ABSTRACT FROM AUTHOR]

Facile charge transfer between source/drain (S/D) electrodes and organic semiconductor (OSC) channel is crucial for high‐mobility organic field‐effect transistors (OFETs). Herein, a novel OFET geometry is developed by modifying a top‐contact bottom‐gate device structure, termed a buried‐contact OFET, enabling close proximity between the S/D‐OSC interface and conducting channel, consequently decreasing the access contact resistance (RC,acc) and overall contact resistance (RC). Conventional post‐thermal annealing is combined with a burying pressure (pressure‐thermal annealing (PTA)). The synergistic effect of thermal and pressure annealings leads to the softened OSC layer enabling metal electrodes to bury inward by applied pressure. This process induces structural transitions from a top‐contact to buried‐contact configuration, as verified by atomic force microscopy and finite element simulations. Transfer line method and 4‐probe measurements revealed that PTA reduces the contact by 1/3 (65 kΩ cm) and the source‐to‐drain voltage waste due to charge injection from 52% to 31%. Consequently, the field‐effect mobility is four times higher than that of a conventional thermally annealed top‐contact OFET. The density of deep traps (Ntr) is mainly distributed in the OSC bulk responsible for charge injection. Remarkably, the Ntr decreased 30‐fold using PTA, resulting in a shallow sub‐threshold region and a threshold voltage close to zero. [ABSTRACT FROM AUTHOR]

Unsymmetric organic semiconductors have many advantages such as good solubility, rich intermolecular interactions for potential various optoelectronic applications. However, their synthesis is more challenging due to intricate structures thus normally suffering tedious synthesis. Herein, we report a trisulfur radical anion (S3⋅−) triggered domino thienannulation strategy for the synthesis of dibenzo[d,d′]thieno[2,3‐b;4,5‐b′]dithiophenes (DBTDTs) using readily available 1‐halo‐2‐ethynylbenzenes as starting materials. This domino protocol features no metal catalyst and the formation of six C−S and one C−C bonds in a one‐pot reaction. Mechanistic study revealed a unique domino radical anion pathway. Single crystal structure analysis of unsymmetric DBTDT shows that its unique unsymmetric structure endows rich and multiple weak S⋅⋅⋅S interactions between molecules, which enables the large intermolecular transfer integrals of 86 meV and efficient charge transport performance with a carrier mobility of 1.52 cm2 V−1 s−1. This study provides a facile and highly efficient synthetic strategy for more high‐performance unsymmetric organic semiconductors. [ABSTRACT FROM AUTHOR]

Ion concentrations in the human body are closely tied to crucial biological functions and thus serve as important diagnostic health markers. Biological samples are chemically complex, containing a wide range of ions and molecules, necessitating the use of sensors that are highly selective to the target analyte. In this work, a multi‐ion sensing chip, capable of selectively detecting potassium (K+), sodium (Na+), and calcium (Ca2+) ions at physiologically relevant concentrations, is demonstrated. Each sensor consists of a simple, solution‐processed, all solid‐state, and low‐voltage organic thin film transistor, functionalized with polyvinyl chloride (PVC) ion selective membranes sandwiched between the insulator and gate electrode. The sensors are responsive to 4–5 decades of each primary ion. When a response from interfering ions is seen at higher concentrations, the sensors can uniquely discriminate between primary and interfering ions by a difference in the polarity of the current modulation. The sensors function well in mixed‐ion solutions, and can detect K+, Na+, and Ca2+ in simulated human blood serum, demonstrating the feasibility of using these devices for the analysis of complex analytes. This work represents an important step toward the development of simple, inexpensive organic multi‐ion sensors. [ABSTRACT FROM AUTHOR]

Unsymmetric organic semiconductors have many advantages such as good solubility, rich intermolecular interactions for potential various optoelectronic applications. However, their synthesis is more challenging due to intricate structures thus normally suffering tedious synthesis. Herein, we report a trisulfur radical anion (S3⋅−) triggered domino thienannulation strategy for the synthesis of dibenzo[d,d′]thieno[2,3‐b;4,5‐b′]dithiophenes (DBTDTs) using readily available 1‐halo‐2‐ethynylbenzenes as starting materials. This domino protocol features no metal catalyst and the formation of six C−S and one C−C bonds in a one‐pot reaction. Mechanistic study revealed a unique domino radical anion pathway. Single crystal structure analysis of unsymmetric DBTDT shows that its unique unsymmetric structure endows rich and multiple weak S⋅⋅⋅S interactions between molecules, which enables the large intermolecular transfer integrals of 86 meV and efficient charge transport performance with a carrier mobility of 1.52 cm2 V−1 s−1. This study provides a facile and highly efficient synthetic strategy for more high‐performance unsymmetric organic semiconductors. [ABSTRACT FROM AUTHOR]

[1]Benzothieno[3,2‐b][1]benzothiophenes (BTBTs) are important molecules that have been extensively studied as high‐performance organic field‐effect transistors (OFETs). Therefore, it is important to develop a simple synthetic method for these molecules. In this paper, a synthetic method to obtain the BTBTs from 2‐arylbenzo[b]thiophenes and elemental sulfur, in which two C−S bonds are formed at once, is described. In this method, molecular iodine plays a very important role as an additive. The role of iodine is discussed in the presumed reaction pathways. [ABSTRACT FROM AUTHOR]

Among a wide variety of polymer-based dielectric materials, aromatic polyimide (PI) and its derivatives have garnered significant attention as gate dielectrics for use in organic thin-film transistors (OTFTs) due to their flexibility, large-area processability, high-temperature resistance, and cost-effectiveness. In this work, we utilized a structure fine-tuning manner by incorporating different amounts of methyl groups into the PI backbone. Two solution-processable aromatic PI-derived materials were prepared using the low-temperature chemical imidization method, and they displayed good film-forming properties, excellent thermal stability, low leakage current density, and low dielectric loss, providing a solid foundation for their use as OTFT gate dielectric layers. As a proof of concept, we utilized these two PI-derived dielectric layers for application in para-sexiphenyl (p-6P)/vanadyl-phthalocyanine (VOPc) TFT devices. Compared to the pristine PI without methyl groups, the mobility and threshold voltage of the OTFT based on PI containing different amounts of methyl groups as dielectric layers have been significantly improved. The strategy of methyl functionalization on PI side chains reported in this work may offer new possibilities for achieving high mobility and low threshold voltage in OTFTs. [ABSTRACT FROM AUTHOR]

Open-shell oligomers and polymers have exhibited intriguing electronic and magnetic properties, making them highly desirable for a wide range of applications, including ambipolar organic field-effect transistors (OFETs), photodetectors, organic thermoelectrics, and spintronics. Although open-shell ground states have been observed in certain small molecules and doped organic semiconductors, the exploration of open-shell ground-state conjugated polymers is still limited, and the strategies for designing these polymers remain obscure. This review aims to briefly introduce the theory and characterization methods of open-shell conjugated polymers, along with an overview of recent progress and applications. The objective is to stimulate further advancements and investigations in this promising area by shedding light on the potential of open-shell conjugated polymers and the challenges that lie ahead. [ABSTRACT FROM AUTHOR]

Since the first applications of nanohoops in organic electronics appear promising, the time has come to go deeper into their rational design in order to reach high‐efficiency materials. To do so, systematic studies dealing with the incorporation of electron‐rich and/or electron‐poor functional units on nanohoops have to be performed. Herein, the synthesis, the electrochemical, photophysical, thermal, and structural properties of two [4]cyclo‐2,7‐carbazoles, [4]C‐Py‐Cbz, and [4]C‐Pm‐Cbz, possessing electron‐withdrawing units on their nitrogen atoms (pyridine or pyrimidine) are reported. The synthesis of these nanohoops is first optimized and a high yield above 50% is reached. Through a structure‐properties relationship study, it is shown that the substituent has a significant impact on some physicochemical properties (eg HOMO/LUMO levels) while others are kept unchanged (eg fluorescence). Incorporation in electronic devices shows that the most electrically efficient Organic Field‐Effect transistors are obtained with [4]C‐Py‐Cbz although this compound does not present the best‐organized semiconductor layer. These experimental data are finally confronted with the electronic couplings between the nanohoops determined at the DFT level and have highlighted the origin in the difference of charge transport properties. [4]C‐Py‐Cbz has the advantage of a more 2D‐like transport character than [4]C‐Pm‐Cbz, which alleviates the impact of defects and structural organization. [ABSTRACT FROM AUTHOR]

The recently developed vertical structure of organic electrochemical transistors (OECTs) can integrate volatile and non‐volatile functions into one reconfigurable device, making it highly promising. However, comparing with the conventional planar OECT (c‐OECT), the understanding of vertical OECT (v‐OECT) working principles and device engineering strategies is still lacking, impeding rational optimization. Since a major difference between c‐ and v‐OECTs is their charge transport directionality, which is highly influenced by crystallite orientations, the orientation–device structure match thus becomes an important yet outstanding topic for OECTs. Herein, using an n‐type small molecule IDIC‐MEG, investigate how much impact such match can have on OECT performance. The IDIC‐MEG c‐OECT fails to work due to the seriously hindered in‐plane electron transport by face‐on orientation. Surprisingly, simply changing the device structure from planar to vertical allows the resultant v‐OECT to exhibit the highest reported transconductance (46.3 mS) among all small‐molecule OECTs, thanks to the match between face‐on orientation and the vertical structure. Such match also leads to excellent non‐volatility, including highly predictable programmability and good operational stability. This work, for the first time, explicitly demonstrates the significance of orientation–device structure match for OECT optimization, establishing new guidelines for achieving high‐performance volatile and non‐volatile OECTs. [ABSTRACT FROM AUTHOR]

To achieve superior device performance such as low threshold voltage Vth, high maximum on‐current Ion,max, and long retention time in electrolyte‐gated organic synaptic transistors, efficient electrochemical doping and high state retention are essential. However, these characteristics generally show a trade‐off relationship. This work introduces an effective strategy to increase retention time while promoting efficient electrochemical doping. The approach involves blending two polymer semiconductors (PSCs) that have the same backbone but different types of side chains. Polymer synaptic transistors (PSTs) with the blend film showed the lowest Vth, highest Ion,max, longest retention time, and superior cyclic stability compared to PSTs that used films containing only one of the PSCs. The improvement in electrical and synaptic properties achieved through the blend strategy is consistently reproducible and comprehensive. It is attributed this improvement to the increased redox activity and constrained morphological changes observed in the blended PSCs during electrochemical doping, as confirmed by several electrochemical characterizations. This work is the first to increase retention time in PSTs without increasing the crystallinity of polymer film or sacrificing the electrochemical doping efficiency, which has been regarded as an unavoidable compromise in this field. This method provides an effective way to tune synaptic properties for various neuromorphic applications. [ABSTRACT FROM AUTHOR]

2,9‐ and 2,10‐diphenylpentacene were synthesized by direct C−H borylation of ketal‐protected pentacene, followed by halodeboronation, resolution of the dihalo isomers, Suzuki arylation, cleavage of the ketals and decarbonylation in the solid state. They were studied as main active components in organic field effect transistors (OFETs). Diphenyl substitution of pentacene affects the unit cell dimensions only slightly, preserving a face to edge molecular packing in the first layers of thin films evaporated on SiO2 substrates. Both isomers self‐assemble into nanoribbons during the thin film growth upon vapor deposition. The similarity between the surface induced phases of the 2,9‐isomer and unsubstituted pentacene leads to similar 4‐probe hole mobilities, i. e. 0.13 cm2 V−1 s−1 for the former. Whereas 2,9‐disubstitution thus does essentially preserve the thin film characteristics of unsubstituted pentacene, 2,10‐disubstitution is detrimental to the molecular ordering in the thin films and therefore to the field effect mobility which is only 0.07 cm2 V−1 s−1. The known strong enhancement of field effect mobility observed upon diphenyl substitution of anthracene can thus not be emulated analogously with pentacene. [ABSTRACT FROM AUTHOR]

Benzothienobenzothiophenes (BTBTs) are a class of heteroacenes for which two distinct isomers have been identified depending on the locations of the fused benzothiophene motifs. Benzothienobenzothiophenes represent a class of heteroacenes demonstrating remarkable electronic properties that make them prominent in the realm of organic semiconductors. The structure of BTBTs, incorporating two sulfur atoms, contributes to their unique electronic characteristics, including narrow bandgaps and effective charge transport pathways. These compounds have gained attention for their high charge carrier mobility, making them desirable candidates for application in organic field‐effect transistors (OFETs) and other electronic devices. Researchers have explored various synthetic strategies to design and tailor the properties of BTBT derivatives, leading to advancements in the development of high‐performance organic semiconductors. Various synthetic techniques for benzothienobenzothiophenes have been reported in the literature including multistep synthesis, tandem transformations, electrochemical synthesis, and annulations. This review investigates the generality of each synthetic methodology by highlighting its benefits and drawbacks, and it analyses all synthetic approaches described for the creation of the two isomers. For the advantage of the readers, we have delved upon every mechanism of the reactions that are known. Finally, we have also summarized the synthetic methodologies that are used for making benzothienobenzothiophene analogues for material applications. [ABSTRACT FROM AUTHOR]

Low-voltage operation is one of the prerequisites for the practical applications of the organic thin-film transistors (OTFTs). Up to date, the most reported low-voltage operatable OTFTs use a bottom-gate structure, and are fabricated by several different technologies in the whole process, in which the organic semiconductors and/or gate dielectrics are prepared in the expensive vacuum equipment. The simple fabricating technologies and fewer processes can better demonstrate the inherent advantages, and enhance the commercial competitiveness of OTFTs. Here, we propose a strategy to fabricate the binary polymers gate dielectric by one-step spin-coating in the top-gate structured flexible OTFTs, by which not only the device performances are prominently improved, but also the fabricating process of the OTFTs is minimized. As a result, the flexible OTFTs exhibit a high mobility over 0.5 cm2 Vs−1, low threshold voltage near to −0.5 V, and excellent mechanical bending durability with a very slightly performances degradation after the tensile and compressive bending at a small curvature radius of 3.0 mm over 1000 cycles. [ABSTRACT FROM AUTHOR]

Charge modulation microscopy (CMM) is an electro-optical method that is capable of mapping the spatial distribution of induced charges in an organic field-effect transistor (OFET). Here, we report a new (and simple) implementation of CMM in transmission geometry with camera-based imaging. A significant improvement in data acquisition speed (by at least an order of magnitude) has been achieved while preserving the spatial and spectral resolution. To demonstrate the capability of the system, we measured the spatial distribution of the induced charges in an OFET with a polymer blend of indacenodithiophene-co-benzothiadiazole and poly-vinylcarbazole that shows micrometer-scale phase separation. We were able to resolve spatial variations in the accumulated charge density on a length scale of 500 nm. We demonstrated through a careful spectral analysis that the measured signal is a genuine charge accumulation signal that is not dominated by optical artifacts. [ABSTRACT FROM AUTHOR]

Von Neumann architecture-based computing, while widely successful in personal computers and embedded systems, faces inherent challenges including the von Neumann bottleneck, particularly amidst the ongoing surge of data-intensive tasks. Neuromorphic computing, designed to integrate arithmetic, logic, and memory operations, has emerged as a promising solution for improving energy efficiency and performance. This approach requires the construction of an artificial synaptic device that can simultaneously perform signal processing, learning, and memory operations. We present a photo-synaptic device with 32 analog multi-states by exploiting field-effect transistors based on the lateral heterostructures of two-dimensional (2D) WS2 and MoS2 monolayers, formed through a two-step metal–organic chemical vapor deposition process. These lateral heterostructures offer high photoresponsivity and enhanced efficiency of charge trapping at the interface between the heterostructures and SiO2 due to the presence of the WS2 monolayer with large trap densities. As a result, it enables the photo-synaptic transistor to implement synaptic behaviors of long-term plasticity and high recognition accuracy. To confirm the feasibility of the photo-synapse, we investigated its synaptic characteristics under optical and electrical stimuli, including the retention of excitatory post-synaptic currents, potentiation, habituation, nonlinearity factor, and paired-pulse facilitation. Our findings suggest the potential of versatile 2D material-synapse with a high density of device integration. [ABSTRACT FROM AUTHOR]

Pyrediyne, a recent addition to the 2D organic nanomaterials family, is known for its improved electrical conductivity, which can have potential applications in the performance of thin film transistors, field effect transistors, and charge storage devices. It has been shown that similar to carbon quantum dots, pyrediyne quantum dots (PDYQDs) can also be generated from 2D pyrediyne nanosheets and can be utilized for imaging cancer cells. In this context, it is highly desirable to enhance the photoluminescence properties of PDYQDs in order to improve the quality of quantum dots‐based cell imaging techniques. Herein, PDYQDs are effectively functionalized using aqueous functionalization agents such as NH3, PEG200, and PEG20000 via a simple and cost‐effective methodology, which resulted in a significant enhancement in the emission quantum yield (QY) (up to 30.2 %) through effectively reducing the non‐radiative recombination centers. After confirming their cytocompatibility using in vitro studies, the amine‐functionalized PDYQDs were utilized for imaging L929 mouse fibroblast cells. The findings in the present study suggest that it is worth exploring various surface functionalization techniques to enhance the applications of novel carbon‐based nano‐structures in various biological and optoelectronic devices. [ABSTRACT FROM AUTHOR]

The voltage-gated ion channels, also known as ionic transistors, play substantial roles in biological systems and ion-ion selective separation. However, implementing the ultrafast switchable capabilities and polarity switching of ionic transistors remains a challenge. Here, we report a nanofluidic ionic transistor based on carbon nanotubes, which exhibits an on/off ratio of 104 at operational gate voltage as low as 1 V. By controlling the morphology of carbon nanotubes, both unipolar and ambipolar ionic transistors are realized, and their on/off ratio can be further improved by introducing an Al2O3 dielectric layer. Meanwhile, this ionic transistor enables the polarity switching between p-type and n-type by controlled surface properties of carbon nanotubes. The implementation of constructing ionic circuits based on ionic transistors is demonstrated, which enables the creation of NOT, NAND, and NOR logic gates. The ionic transistors are expected to have profound implications for low-energy consumption computing devices and brain-machine interfacing. [ABSTRACT FROM AUTHOR]

Organic semiconductors (OSCs), especially small molecule semiconductors, have received increasing attention due to their good designability and variability. Phase transitions and interfacial properties have a decisive influence on device performance. Here, 2-Dodecyl-7-phenyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-12) devices are treated with low-power laser annealing, which is able to avoid the influence of the dewetting effect on the hole mobility of organic semiconductor materials. Ultraviolet ozone treatment and self-assembled monolayer treatment can improve the performance and stability of the device. Moreover, after low-temperature thermal annealing, the hole mobility of the device can even reach as high as 4.80 cm2 V−1 s−1, and we tested the optical response of the device to the ultraviolet wavelength and found that its maximum optical responsivity was 8.2 AW−1. [ABSTRACT FROM AUTHOR]

The synergistic effect between surface metal vacancies and a Schottky junction on enhanced transconductance, and the gating effect of an organic photoelectrochemical transistor was reported. [ABSTRACT FROM AUTHOR]

Tunability in electronic and optical properties has been intensively explored for developing conjugated polymers and their applications in organic and perovskite‐based electronics. Particularly, the charge carrier mobility of conjugated polymer semiconductors has been deemed to be a vital figure‐of‐merit for achieving high‐performance organic field‐effect transistors (OFETs). In this study, the systematic hole carrier mobility improvement of benzo[1,2‐b:4,5‐b']dithiophene‐based conjugated polymer in perovskite‐functionalized organic transistors is demonstrated. In conventional OFETs with a poly(methyl methacrylate) (PMMA) gate dielectric, improvements in hole mobility of 0.019 cm2 V−1 s−1 are measured using an off‐center spin‐coating technique, which exceeds those of on‐center counterparts (0.22 ± 0.07 × 10−2 cm2 V−1 s−1). Furthermore, the mobility drastically increases by adopting solid‐state electrolyte gating, corresponding to 2.99 ± 1.03 cm2 V−1 s−1 for the control, and the best hole mobility is 8.03 cm2 V−1 s−1 (average ≈ 6.94 ± 0.59 cm2 V−1 s−1) for perovskite‐functionalized OFETs with a high current on/off ratio of >106. The achieved device performance would be attributed to the enhanced film crystallinity and charge carrier density in the hybrid perovskite‐functionalized organic transistor channel, resulting from the high‐capacitance electrolyte dielectric. [ABSTRACT FROM AUTHOR]

Heteroacenes are considered as an important class of compounds for material applications due to their stability, electron‐richness and tunable properties. Mostly, four ring containing heteroacenes have found immense applications in organic electronic devices and some of them have been successfully commercialized. One such class of heteroacene are benzothienobenzofuran for which four different isomers are reported to date based on the position where the benzothiophene unit is fused to the benzofuran ring. The available literature claims different synthetic strategies towards the benzothienobenzofurans starting from multistep synthesis to tandem transformations, electrochemical synthesis and annulations. Different metal catalyzed transformations including Pd‐catalyzed dual C−H activations, Ullmann coupling, dual metal‐catalyzed one‐pot processes etc. are reported for the synthesis of different isomers of benzothienobenzofurans. The present review analyses all the synthetic methodologies reported for the preparation of the four isomers and examines the generality of each method by highlighting its advantages and disadvantages. We discuss all available mechanisms of the reactions for the benefit of the readers. Finally, the existing basic photophysical properties of benzothienobenzofurans and their limited applications in fabricating devices for organic light‐emitting diode (OLED), organic field‐effect transistor (OFET), and organic phototransistor (OPT) uses are deliberated [ABSTRACT FROM AUTHOR]

This work presents a series of novel quinoidal organic semiconductors based on diselenophene‐dithioalkylthiophene (DSpDST) conjugated cores with various side‐chain lengths (‐thiohexyl, ‐thiodecyl, and ‐thiotetradecyl, designated DSpDSTQ‐6, DSpDSTQ‐10, and DSpDSTQ‐14, respectively). The purpose of this research is to develop solution‐processable organic semiconductors using dicyanomethylene end‐capped organic small molecules for organic field effect transistors (OFETs) application. The physical, electrochemical, and electrical properties of these new DSpDSTQs are systematically studied, along with their performance in OFETs and thin film morphologies. Additionally, the molecular structures of DSpDSTQ are determined through density functional theory (DFT) calculations and single‐crystal X‐ray diffraction analysis. The results reveal the presence of intramolecular S (alkyl)···Se (selenophene) interactions, which result in a planar SR‐containing DSpDSTQ core, thereby promoting extended π‐orbital interactions and efficient charge transport in the OFETs. Moreover, the influence of thioalkyl side chain length on surface morphologies and microstructures is investigated. Remarkably, the compound with the shortest thioalkyl chain, DSpDSTQ‐6, demonstrates ambipolar carrier transport with the highest electron and hole mobilities of 0.334 and 0.463 cm2 V−1 s−1, respectively. These findings highlight the excellence of ambipolar characteristics of solution‐processable OFETs based on DSpDSTQs even under ambient conditions. [ABSTRACT FROM AUTHOR]

Stochastic resonance (SR) is an intriguing phenomenon in which noise, typically considered a detrimental aspect of electronic communication systems, assumes a beneficial role in the detection of undetectable signals. The SR phenomenon for detecting low-intensity optical signals using PBTTT-C14-based organic field-effect transistors (OFETs) is being reported. In this discourse, we explicate the sensing of an undetectable periodic optical signal with a frequency of 5 Hz, using a PBTTT-C14-based OFETs in the presence of a finite and optimal quantity of Gaussian noise (noise bandwidth of 1 Hz and noise amplitude of 2.0, 4.0, 6.0, and 7.5 V). The detection of higher harmonics for optical signals using the SR phenomenon has not been hitherto explored for OFETs. This report presents a noteworthy finding elucidating the detection of the principal frequency and also higher harmonics of the optical signal. This simplistic methodology for examining the SR phenomenon holds great promise in identifying its robust utility in diverse real-world contexts. [ABSTRACT FROM AUTHOR]

Gas sensors based on ambipolar carbon nanotube (CNT) field-effect transistors with various amounts of CNTs were fabricated by dielectrophoretic assembly. The nitrogen dioxide (NO2) gas response and recovery properties of the transistors were measured to investigate the effect of CNT amount on gas response. For the device with a small amount of CNTs, responses from the CNT bulk and CNT/electrode contacts were observed. For devices with a large amount of CNTs, in which a network-like structure of CNTs was observed near the electrodes, an increased current in both electron and hole conduction regions was observed compared with that for the device with a small amount of CNTs. The increased current in the electron conduction region rapidly decreased during recovery. This response is consistent with that of CNT/CNT X-type contacts, which have a high resistance before NO2 adsorption. Equivalent circuits of CNT channels with CNT/CNT contacts were developed, allowing the transistor behavior to be qualitatively discussed. Evaluation of time constants revealed that CNT/electrode contacts and CNT/CNT X-type contacts exhibited high NO2 adsorption and desorption rates, respectively. [ABSTRACT FROM AUTHOR]