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Rubrene is one of the leading organic semiconductors in scientific and industrial research, showing good conductivities and utilities in devices such as organic field-effect transistors. In these applications, the rubrene crystals often contact ionic liquids and other materials. Consequently, their surface properties and interfacial interactions influence the device's performance. Although rubrene has been extensively studied with multiple structure characterization techniques, a complete description of the structure of rubrene single-crystal surfaces at the molecular level remains elusive. This study elucidates the molecular orientation and arrangement on the surface of rubrene single crystals with sum frequency generation (SFG) spectroscopy and reflection high-energy electron diffraction, respectively. The results confirm the near-surface unit cells with in-plane lattice parameters of a = 7.24 Å and b = 14.3 Å and an out-of-plane constant of c = 26.9 Å. Furthermore, the SFG analysis yields the tilt and rotation angles of θ = 15° and φ = 43° with respect to the crystalline c and a axes, respectively, and an in-plane twist of ψ = 3° for the surface phenyl rings. [ABSTRACT FROM AUTHOR]

Organic multilayer systems, which are stacked layers of different organic materials, are used in various organic electronic devices such as organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs). In particular, OFETs are promising as key components in flexible electronic devices. In this study, we investigated how the inclusion of an insulating tetratetracontane (TTC) interlayer in ambipolar indigo-based OFETs can be used to alter the crystallinity and electrical properties of the indigo charge transport layer. We find that the inclusion of a 20-nm-thick TTC film thermally annealed at a low temperature of 70 °C acts to significantly increase the ambipolar electrical transport of the indigo layer. X-ray diffraction, atomic force microscopy, and vibrational sum frequency generation measurements showed that annealing the TTC film significantly improved its ordering. The electronic sum-frequency generation spectra of TTC/indigo bilayers show that this improved ordering of TTC films promotes the growth of crystalline indigo films that exhibit charge mobilities in OFET that are nearly an order of magnitude larger than those measured for devices grown on unannealed TTC layers. Furthermore, using vibrational sum-frequency generation spectroscopy, we found that pre-annealing the TTC layer prior to indigo deposition can suppress the formation of defects within the TTC layer during indigo film growth, which also contributes to enhanced charge transport. Our results highlight the importance of controlling the molecular ordering within the interlayer contacts in OFET structures to achieve an enhanced performance. [ABSTRACT FROM AUTHOR]

Alkylated benzothienobenzothiophenes are an important class of organic semiconductors that exhibit high performance in solution-processed organic field-effect transistors. In this work, we study the near-edge x-ray absorption fine-structure (NEXAFS) spectra of 2,7-didecyl[1]benzothieno[3,2-b][1]benzothiophene (C10-BTBT) at both the carbon and sulfur K-edges. Angle-resolved experiments of thin films are performed to characterize the dichroism associated with molecular orientation. First-principles calculations using the density functional theory-based many-body x-ray absorption spectroscopy (MBXAS) method are also performed to correlate the peaks observed and their dichroism with transitions to specific antibonding molecular orbitals. Interestingly, the dichroism of the dominant, lowest energy peak is opposite at the carbon and sulfur K-edges. While the low-energy peak at the carbon K-edge is assigned to carbon 1s → π* transitions with transition dipole moment (TDM) perpendicular to the planar BTBT core, the dominant low energy peak at the sulfur K-edge is assigned to sulfur 1s → σ* transitions with TDM oriented along the long axis of the BTBT core. These differences at the sulfur and carbon K-edges are understood through the MBAXS simulations that find a reordering of the energy of the lowest energy π* and σ* transitions at the sulfur K-edge due to the strong localization of the σ* orbital over the sulfur atom. This work highlights differences in the NEXAFS spectra of organic semiconductors at carbon and sulfur K-edges and provides new insights into peak assignment and x-ray dichroism relevant for studying the molecular orientation of organic semiconductor films. [ABSTRACT FROM AUTHOR]

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]

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]

In order to achieve high sensitivity in gas-sensors based on organic field-effect transistors (OFETs), the most crucial and direct approach to enhance their sensing performance and reduce response and recovery times was through appropriate modification or improvement of the organic semiconductor (OSC) layer, such as altering its surface morphology or structure. The micro/nanostructure of spin-coated copper phthalocyanine (CuPc) films was controlled by utilizing polyvinyl alcohol ordered nanofibers (PVA ONFs). The electrical and gas-sensitive properties of CuPc/PVA ONF films were investigated and analyzed. CuPc/PVA ONF film transistors exhibited improved output and transfer characteristics when the CuPc solution concentration was 75 mg mL−1, with a mobility (μ) of 6.90 × 10−4 cm2 V−1 s−1. Compared with the spin-coated CuPc film transistors, the mobility increased by 74.24%. The sensors demonstrated a relative response of 12 942% to 20 ppm NO2 gas. Additionally, they showed a response time of 1.49 min and a recovery time of 2.32 min. The response rate reached up to 90%, while the sensitivity was measured at 611%/ppm, and the limit of detection (LOD) stood at 0.2 ppm. The research presented in this article advances the potential applications of phthalocyanine materials within the realm of flexible and 3D-printed sensing technologies. [ABSTRACT FROM AUTHOR]

Organic photoelectrochemical transistor (OPECT)-based sensors that use light-sensitive semiconductor materials as the gate have recently garnered increasing interest in various fields ranging from biological analysis to environmental monitoring. However, so far, the working principle and representative applications of OPECT sensors have not been discussed and reviewed systematically. In this review, we aim to present a comprehensive overview of the working principle and sensing mechanisms of OPECT-based sensors and various inorganic and organic photoactive gate materials used in OPECTs, with a focus on the representative applications and recent progress of these sensors in the fields of enzyme sensing, immunoassays, and nucleic acid-based sensing. Moreover, the challenges and outlooks that need to be addressed for future advancements in this field are summarized and discussed. This review will assist researchers in gaining a more comprehensive understanding and cognition of new OPECT-based sensing methods and devices. [ABSTRACT FROM AUTHOR]

Recent advancements in conjugated polymer-based gas sensors have highlighted the critical role of side-chain engineering in optimizing organic field-effect transistor (OFET) performance for gas detection. This review provides a comprehensive analysis of how structural modifications of side chains in conjugated polymers affect the electrical properties of OFETs, as well as the sensitivity and selectivity of OFET-based gas sensors. We first explore modifications of alkyl side chains and their impact on the electrical characteristics of conjugated polymers. Then, we discuss how functionalized side chains and additives can significantly enhance sensor performance by improving detection limits and selectivity. Special attention is given to glycol-based side chains, particularly in enhancing NO2 sensitivity, and the role of alkyl side chain length in tuning gas sensing capabilities. This review aims to elucidate the intricate relationships between side chain modifications and sensor performance, offering insights for the development of advanced OFET-based gas sensors with improved sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

In addition to traditional rubber applications, 1,4‐cis‐polyisoprene (cis‐PI) has been utilized in wearable electronics. While synthetic PI typically exhibits lower durability compared to natural rubber (NR), high‐molecular‐weight cis‐PI compensates by offering improved mechanical properties and chemical resistance. The group proposes using a commercial cis‐PI with high molecular weight of 250 000 g mol−1 (PI250K‐C) grafted onto modified nanoparticle structures including silicon dioxide (mSiO2), rutile titanium dioxide (mRTiO2), and anatase titanium dioxide (mATiO2) as an insulator in organic field effect transistors (OFETs) due to its naturally low dielectric constant. The nanoparticles are pretreated with a coupling agent to improve adhesion and prevent aggregation. Rubber composite films, designated X%‐mY‐PI250K‐C (where X = 10, 20, 30% and Y = mSiO2, mRTiO2, mATiO2), are fabricated using sulfur vulcanization. The modified films demonstrate excellent mechanical stress (1.15 ± 0.1 MPa) and elasticity, enduring 50 loading–unloading cycles without residual strain. In contrast, rubber composites produced from simple blending show half the mechanical stress at 0.7 ± 0.3 MPa, which is attributed to nanoparticle agglomeration observed in SEM and EDX results. Additionally, mRTiO2 nanoparticles significantly increase the dielectric constant of PI250K‐C from 2.12 to 12.93, enhancing electrical performance for TFT applications. This study underscores the effectiveness of the “grafting to” approach for producing robust rubber composites, highlighting the importance of nanoparticle selection and fabrication precision for stretchable organic electronics. [ABSTRACT FROM AUTHOR]

C‐shaped ortho‐benzodipyrrole‐based A‐DNBND‐A non‐fullerene acceptors (NFAs), derived from the removal of the A′ thiadiazole moiety in Y6, emerge as a new class of structurally simplified A‐D‐A‐type NFAs. In this work, a selenium‐substitution strategy is applied to the central DNBND ladder‐π‐core, yielding asymmetric CB‐Se and symmetric CB‐2Se. Asymmetric CB‐Se demonstrates a less ordered 3D trapezoid‐like packing structure, which promotes a more favorable intermixed donor‐acceptor morphology with PM6 polymer, achieving a higher power conversion efficiency (PCE) of 17.87% in organic photovoltaics (OPVs). This value represents the highest reported value among the selenium‐incorporated A‐D‐A‐type NFAs. Symmetric CB‐2Se forms a kaleidoscope‐like 3D single‐crystal structure with enhanced intermolecular interactions. This enables the development of a single‐crystal‐like solution‐processed thin film, which transitions from a kinetically trapped face‐on π–π stacking orientation to a thermodynamically stable edge‐on configuration upon thermal annealing. The CB‐2Se‐based organic field‐effect transistor (OFET) achieved a remarkable electron mobility of 1.18 cm2 V−1 s−1 with exceptional n‐type air stability, which outperformed the corresponding A‐DNA′ND‐A‐type Y6‐based materials by two orders magnitudes and represents the highest reported value for solution‐processed n‐type OFETs utilizing A‐D‐A‐type small molecules. [ABSTRACT FROM AUTHOR]

Drosophila can rapidly and precisely detect changes in light in their surroundings and achieve acute perception of motion information with high energy efficiency and adaptivity owing to the cooperation of “ON” channel and the “OFF” channel in its visual system. Optical controlled bidirectional synaptic behavior of neuromorphic device is important for modeling parallel processing channels of Drosophila's visual system. In this study, an ambipolar transistor utilizing a bilayer architecture composed of p‐type pentacene and n‐type C60 as semiconductors is developed, with near‐infrared (NIR) PbS quantum dots serving as the charge‐trapping layer. This design enables a gate‐tunable positive and negative photoresponse, driven by photogating and photovoltaic effects at visible and NIR wavelengths. When regulated by a negative gate voltage, the device exhibits a suppressed photocurrent relaxation time exceeding 1000 s, demonstrating stable long‐term inhibitory characteristics. Consequently, high‐contrast excitatory and inhibitory synapses facilitate orientation and motion detection. Identification accuracies of up to 94.8% for motion direction and 98.1% for dynamic gestures are achieved. Practical applications such as intelligent monitoring and human–computer interaction stand to benefit significantly from these findings. [ABSTRACT FROM AUTHOR]

Incorporation of regular order pores/holes/defects into semimetalic graphene sheets can tune the band gap up to 1 eV or more introducing semiconducting property and therefore exhibiting promising applications for organic electronics such as field‐effect transistors (FETs), molecular sieve membranes, gas sensing, catalysis devices, etc. In this mini review, we focused on bottom‐up approaches to introduce periodic homogeneous pores into graphene and nanographene and graphene nanoribbons along with their characteristics and potential applications in various fields. [ABSTRACT FROM AUTHOR]

Small molecule/polymer semiconductor blends are promising solutions for the development of high‐performing organic electronics. They are able to combine ease in solution processability, thanks to the tunable rheological properties of polymeric inks, with outstanding charge transport properties thanks to high crystalline phases of small molecules. However, because of charge injection issues, so far such good performances are only demonstrated in ad‐hoc device architectures, not suited for high‐frequency applications, where transistor dimensions require downscaling. Here, the successful integration of the most performing blend reported to date, based on 2,7‐dioctyl[1] benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) and poly(indacenodithiophene‐co‐benzothiadiazole) (C16IDT‐BT), in OFETs characterized by channel and overlap lengths equal to 1.3 and 1.9 µm, respectively, is demonstrated, enabling a transition frequency of 23 MHz at ‐8 V. Two key aspects allowed such result: molecular doping, leading to width‐normalized contact resistance of only 260 Ωcm, allowing to retain an apparent field‐effect mobility as high as 3 cm2/(Vs) in short channel devices, and the implementation of a high capacitance dielectric stack, enabling the reduction of operating voltages below 10 V and the overcoming of self‐heating issues. These results represent a fundamental step for the future development of low‐cost and high‐speed printed electronics for IoT applications. [ABSTRACT FROM AUTHOR]

Organic semiconductor (OSC) films fabricated by meniscus‐guided coating (MGC) methods are suitable for cost‐effective and flexible electronics. However, achieving crystalline thin films by MGC methods is still challenging because the nucleation and crystal growth processes are influenced by the intertwined interactions among solvent evaporation, stochastic nucleation, and the fluid flow instabilities. Herein, a novel flexible fountain pen with active ink supply is designed and used to print OSCs. This direct‐write method allows the flexible pen tip to contact the substrate, maintaining a robust meniscus by eliminating the gap found in conventional MGCs. An in situ optical microscopy observation system shows that the precursor film plays a critical role on the crystallization and the formation of coffee rings and dendrites. The computational fluid dynamics simulations demonstrate that the microstructure of the pen promotes extensional flows, facilitating mass transport and crystal alignment. Highly‐aligned ribbon‐shaped crystals of a small organic molecule (TIPS‐pentacene), as well as a semiconducting polymer (N2200) with highly‐ordered orientations, have been successfully printed by the flexible fountain pen. Organic field‐effect transistors based on the flexible pen printed OSCs exhibit high performances and strong anisotropic mobility. In addition, the flexible fountain pen is expandable for printing multiple lines or large‐area films. [ABSTRACT FROM AUTHOR]

Dye‐containing polymers P1 (PEDPP‐OT‐BDT) and P2 (PEDPP‐OT‐BDTT) including a π‐extended diketopyropyrrole (DPP) derivative and electron‐rich thiophene fused ring units (4,8‐bis((2‐ethylhexyl)oxy)benzo[1,2‐b:4,5‐b′]dithiophene for P1 and 4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene for P2) were synthesized as narrow band gap dyes. A π‐extended DPP (EDPP‐OT‐BrPh), fragment of the polymers P1 and P2, was obtained by extending the π‐conjugation of DPP using Ru(III)‐catalyzed C−H and N−H activation reported by Gońka et al. in 2019, exhibiting a high quantum yield (ϕem=0.84) and small HOMO‐LUMO gap (Eg=1.69 eV) due to the spatial overlap of the HOMO and LUMO orbitals. The solubility of the π‐extended DPP was improved by introducing four 2‐octylthophene side chains around the periphery of the planer dye moiety, while maintaining the high planarity of the dye molecule, which is essential to the function of optoelectronic devices. As a result, P1 and P2, polymerized with the π‐extended DPP and BDT derivatives, exhibit carrier mobility of approximately 10−5 cm2/Vs in organic field‐effect transistors (OFETs). In bulk heterojunction (BHJ) solar cells with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM), they demonstrate a power conversion efficiency (PCE) of 1.0 % with an average transmittance (AVTs) of around 60 %. [ABSTRACT FROM AUTHOR]

The performance of organic field-effect transistors (OFETs) is highly dependent on the dielectric–semiconductor interface, especially in ion-gel-gated OFETs, where a significantly high carrier density is induced at the interface at a low gate voltage. This study investigates how altering the alkyl side chain length of donor–acceptor (D-A) copolymers impacts the electrical performance of ion-gel-gated OFETs. Two difluorobenzothiadiazole-based D-A copolymers, PffBT4T-2OD and PffBT4T-2DT, are compared, where the latter features longer alkyl side chains. Although PffBT4T-2DT shows a 2.4-fold enhancement of charge mobility in the SiO2-gated OFETs compared to its counterpart due to higher crystallinity in the film, PffBT4T-2OD outperforms PffBT4T-2DT in the ion-gel-gated OFETs, manifested by an extraordinarily high mobility of 17.7 cm2/V s. The smoother surface morphology, as well as stronger interfacial interaction between the ion-gel dielectric and PffBT4T-2OD, enhances interfacial charge accumulation, which leads to higher mobility. Furthermore, PffBT4T-2OD is blended with a polymeric elastomer SEBS to achieve ion-gel-gated flexible OFETs. The blend devices exhibit high mobility of 8.6 cm2/V s and high stretchability, retaining 45% of initial mobility under 100% tensile strain. This study demonstrates the importance of optimizing the chain structure of polymer semiconductors and the semiconductor–dielectric interface to develop low-voltage and high-performance flexible OFETs for wearable electronics applications. [ABSTRACT FROM AUTHOR]

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Organic electroactive materials, particularly semiconducting polymers, are at the forefront of emerging organic electronics. Among the plethora of unique features, the possibility to formulate inks out of these materials is particularly promising for the large‐scale manufacturing of electronics at lower cost on a variety of soft substrates. While solution deposition of semiconducting materials is promising for developing printed electronics, the environmental footprint of the materials and related devices needs to be considered to achieve sustainable manufacturing. Towards the development of greener printed electronics, this work investigates the utilization of a non‐toxic, environmentally‐friendly solvent, namely branched polyethylene (BPE), to formulate semiconducting inks. Focusing on a diketopyrrolopyrrole‐based (DPP) semiconducting polymer, shellac as dielectric, and BPE as the solvent, solutions were prepared in different concentrations and their rheological properties were characterized. Then, printing on polyethylene terephthalate (PET) substrates using two different techniques was performed to fabricate organic field‐effect transistors (OFETs). Both printing techniques yielded OFETs with good performance and device characteristics, averaging approximately 10−2 and 10−4 cm2 V−1 s−1, respectively, for slot‐die coating and direct‐ink writing deposition. Notably, despite some difference in threshold voltages, OFETs produced via slot‐die coating and direct‐ink writing showed comparable charge mobilities to previously reported OFETs prepared from similar materials, particularly those prepared on silicon dioxide wafers. Overall, this work confirms the suitability of BPE to formulate semiconducting inks to develop printed electronics in a greener manner. The printing methodology developed in this work also open new avenues for the design of functional printed electronics and related technologies. [ABSTRACT FROM AUTHOR]

This study introduces the first fluorene‐flanked diketopyrrolopyrrole (FDPP)‐based semiconducting polymers, named Boc‐FDPP‐CoMs (CoM = TT or BT), synthesized via copolymerization of tert‐butoxycarbonyl (t‐Boc)‐substituted FDPP as the acceptor unit with thieno[3,2‐b]thiophene (TT) or bithiophene (BT) as the donor comonomers. The incorporation of t‐Boc groups addresses challenges related to poor solubility and polymer backbone twisting associated with the FDPP building block. While Boc‐FDPP‐CoMs demonstrate solubility in common organic solvents, facilitating favourable solution‐processability for uniform film fabrication, they exhibit significant backbone twisting, leading to poor charge transport properties. Post‐deposition thermal annealing at a mild temperature as low as 170°C conveniently removes t‐Boc groups. The resulting t‐Boc‐free copolymers, NH‐FDPP‐TT and NH‐FDPP‐BT, exhibit hole mobilities up to 5.0 × 10−3 and 2.2 × 10−3 cm2 V−1 s−1 in organic field effect transistors (OFETs), respectively, representing a substantial increase compared to their counterparts with t‐Boc groups. This study underscores a meticulously designed strategy for achieving solution solubility and backbone coplanarity through side‐chain engineering for FDPP and potentially other sterically demanding building blocks to construct high‐performance semiconducting polymers for OFETs and other applications. [ABSTRACT FROM AUTHOR]

A key component of organic bioelectronics is electrolyte‐gated organic field‐effect transistors (EG‐OFETs), which have recently been used as sensors to demonstrate label‐free, single‐molecule detection. However, these devices exhibit limited stability when operated in direct contact with aqueous electrolytes. Ultrahigh stability is demonstrated to be achievable through the utilization of a systematic multifactorial approach in this study. EG‐OFETs with operational stability and lifetime several orders of magnitude higher than the state of the art have been fabricated by carefully controlling a set of intricate stability‐limiting factors, including contamination and corrosion. The indacenodithiophene‐co‐benzothiadiazole (IDTBT) EG‐OFETs exhibit operational stability that exceeds 900 min in a variety of widely used electrolytes, with an overall lifetime exceeding 2 months in ultrapure water and 1 month in various electrolytes. The devices were not affected by electrical stress‐induced trap states and can remain stable even in voltage ranges where electrochemical doping occurs. To validate the applicability of our stabilized device for biosensing applications, the reliable detection of the protein lysozyme in ultrapure water and in a physiological sodium phosphate buffer solution for 1500 min was demonstrated. The results show that polymer‐based EG‐OFETs are a viable architecture not only for short‐term but also for long‐term biosensing applications. [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]

Highlights: Photonic synapse capable of multispectral color discrimination is demonstrated. Strong excited-state dipoles enable remarkable discrimination intensity (0.05–40 mW cm-2). This approach is not restricted to a specific medium in the channel layer, and convolutional neural network with synapses array achieves over 94% inference accuracy for Canadian-Institute-For-Advanced-Research-10 images. To emulate the functionality of the human retina and achieve a neuromorphic visual system, the development of a photonic synapse capable of multispectral color discrimination is of paramount importance. However, attaining robust color discrimination across a wide intensity range, even irrespective of medium limitations in the channel layer, poses a significant challenge. Here, we propose an approach that can bestow the color-discriminating synaptic functionality upon a three-terminal transistor flash memory even with enhanced discriminating capabilities. By incorporating the strong induced dipole moment effect at the excitation, modulated by the wavelength of the incident light, into the floating gate, we achieve outstanding RGB color-discriminating synaptic functionality within a remarkable intensity range spanning from 0.05 to 40 mW cm−2. This approach is not restricted to a specific medium in the channel layer, thereby enhancing its applicability. The effectiveness of this color-discriminating synaptic functionality is demonstrated through visual pre-processing of a photonic synapse array, involving the differentiation of RGB channels and the enhancement of image contrast with noise reduction. Consequently, a convolutional neural network can achieve an impressive inference accuracy of over 94% for Canadian-Institute-For-Advanced-Research-10 colorful image recognition task after the pre-processing. Our proposed approach offers a promising solution for achieving robust and versatile RGB color discrimination in photonic synapses, enabling significant advancements in artificial visual systems. [ABSTRACT FROM AUTHOR]

Piperazine‐2,5‐dione (glycine anhydride, GA) has recently emerged as a valuable precursor for high‐performance π‐conjugated polymer semiconductors in organic electronics. We utilized GA to design a novel bisindolin‐dihydropiperazine (IDHP)‐based conjugated polymer, PIDHPTT, for aqueous chemical sensing. In the isatin‐flanked monomer, GA exists as a non‐conjugated lactam (DHP‐NH) but converts to a conjugated lactim (DHP‐OH) form within the polymer. Density functional theory (DFT) calculations show that this conversion is driven by energy minimization via extended π‐conjugation. Neighboring DHP units in the lactim form facilitate this process through π‐bridges, demonstrating a vinylogous effect, which has previously only been observed in small molecules. This is the first study to report such a long‐range vinylogous effect in a polymer due to the collective synergy of numerous functional groups. The OH groups in the lactim DHP interact more strongly with fluoride ions than other halides. PIDHPTT exhibits significant changes in optical absorption, electrochemical impedance, and charge transport in response to fluoride ions, which differ from responses to other halides. A water‐gated organic field‐effect transistor based on PIDHPTT shows excellent sensitivity and selectivity for fluoride ions, demonstrating the potential of this polymer design for chemical sensing applications. [ABSTRACT FROM AUTHOR]

Organic ferroelectric field-effect transistors (Fe-OFETs) exhibit exceptional capabilities in mimicking biological neural systems and represent one of the primary options for flexible artificial synaptic devices. Ferroelectric polymers, such as poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), given their strong ferroelectricity and facile solution processing, have emerged as the preferred choices for the ferroelectric dielectric layer of wearable devices. However, the solution processed P(VDF-TrFE) films can lead to high interface roughness, prone to cause excessive gate leakage. Meanwhile, the ferroelectric layer in neural computing and memory applications also faces a trade-off between storage time and energy for read/write operations. This study introduces a composite dielectric layer for Fe-OFETs, fabricated via a solution-based process. Different thicknesses of poly(N-vinylcarbazole) (PVK) are shown to significantly alter the ferroelectric hysteresis window and leakage current. The optimized devices exhibit synaptic plasticity with a transient current of 3.52 mA and a response time of approximately 50 ns. The Fe-OFETs with the composite dielectric were modeled and integrated into convolutional neural networks, achieving a 92.95% accuracy rate. This highlights the composite dielectric's advantage in neuromorphic computing. The introduction of PVK optimizes the interface and balances device performance of Fe-OFETs for neuromorphic computing. [ABSTRACT FROM AUTHOR]

Organic field-effect transistors (OFETs) require ultra-precise electrical measurements due to their unique charge transport mechanisms and sensitivity to environmental factors, yet commercial semiconductor parameter analysers capable of such measurements are prohibitively expensive for many research laboratories. This study introduces a novel, cost-effective, and portable setup for high-precision OFET characterisation that addresses this critical need, providing a feasible substitute for conventional analysers costing tens of thousands of dollars. The suggested system incorporates measurement, data processing, and graphical visualisation capabilities, together with Bluetooth connectivity for local operation and Wi-Fi functionality for remote data monitoring. The device consists of a motherboard and specialised cards for low-current measurement, voltage measurement, and voltage generation, providing comprehensive OFET characterisation, including transfer and output characteristics, in accordance with IEEE-1620 standards. The system can measure current from picoamperes to milliamperes, with voltage measurements supported by high input resistance (>100 MΩ) and a voltage generation range of −30 V to +30 V. This versatile and accessible approach greatly improves the opportunities for future OFET research and development. [ABSTRACT FROM AUTHOR]

We have demonstrated that electrolyte-gated organic field-effect transistors (EGOFETs) with the semiconductor layer based on [1]benzothieno[3,2-b]benzothiophene and the receptor layer containing 4,13-diaza-18-crown-6 ether can be used as sensors for sodium or potassium ions in solution. The proposed method for fabrication of the receptor layer allows developing a universal platform for the detection of various metal ions using crown ether structures. The EGOFETs with the receptor layer described in this work can operate in electrolyte solutions of high ionic strength, thus providing the possibility to detect sodium and potassium ions in real biological fluid samples. [ABSTRACT FROM AUTHOR]

The work describes one of the stages of development of flexible polymer gas sensors based on organic field-effect transistors (OFETs) and is devoted to revealing the dependencies of the electrical and sensory properties of these devices on the characteristics of the polymer dielectric layer of the OFETs. The influence of the material of the dielectric layer, as well as the conditions of its application to the polymer substrate were investigated. It was shown that the surface morphology and the properties of the semiconductor layer, which was formed on top of the polymer dielectric by thermal evaporation in vacuo, strongly depend on the value of the surface energy of the dielectric used, while the roughness of its layer has no considerable effect on the morphology. The highest electrical characteristics were demonstrated by the OFETs based on the dielectric with the highest value of surface energy, that is, polymethyl methacrylate. At the same time, regardless of the dielectric used, all the sensor devices demonstrate a high sensitivity towards nitrogen dioxide, which has values that are comparable to those characterizing the sensitivity of similar devices fabricated on silicon substrates using the studied dielectrics as interface layers, as well as an ability towards recovery of the starting properties in pure air that is higher compared to that of silicon samples, which is very promising for the commercial application of the developed polymer gas sensors. [ABSTRACT FROM AUTHOR]

The development of complementary metal-oxide-semiconductor field-effect transistor (CMOSFET) based on two-dimensional (2D) materials offers an important opportunity to reduce static power and increase the integration density of integrated circuits. One promising approach to realize these CMOSFETs is to employ ambipolar 2D materials as channel materials with designed device structure to control the carrier transport properties for CMOSFET characteristics. However, these devices always suffer from complex multi-gate electrode structure, and hence face challenges in complicated inter-connection design and excessive voltage source requirement for circuit implementation. Here, we develop a three-terminal CMOSFET using ambipolar 2D material based on the drain electric field-induced carrier injection self-blocking mechanism. The designed drain electrode can effectively suppress carrier injection from the drain to the channel material, while the gate voltage can only regulate carrier injection in the source region. As a result, we can configure the device as either N-field-effect transistors (FET) or P-FET with a high current on/off ratio of over 105 by adjusting the three voltages (gate, source, and drain). Furthermore, we utilize these devices to demonstrate multifunctional wave modulator, low-static-power logic inverter (<5 pW), and combinational logic computing in the form of a compact complementary circuit. Our work would explore an efficient approach for implementing complementary circuits using 2D materials. [ABSTRACT FROM AUTHOR]

Despite recent dramatic improvements in the electronic characteristics of stretchable organic field-effect transistors (FETs), their low operational stability remains a bottleneck for their use in practical applications. Here, the operational stability, especially the bias-stress stability, of semiconducting polymer-based FETs under various tensile strains is investigated. Analyses on the structure of stretched semiconducting polymer films and spectroscopic quantification of trapped charges within them reveal the major cause of the strain-dependent bias-stress instability of the FETs. Devices with larger strains exhibit lower stability than those with smaller strains because of the increased water content, which is accompanied by the formation of cracks and nanoscale cavities in the semiconducting polymer film as results of the applied strain. The strain-dependence of bias-stress stability of stretchable OFETs can be eliminated by passivating the devices to avoid penetration of water molecules. This work provides new insights for the development of bias-stable stretchable OFETs. [ABSTRACT FROM AUTHOR]

Polyimide‐based dielectric films are widely used in various thin film devices including organic field‐effect transistors (OFETs) owing to their promising thermal/chemical stability, mechanical flexibility, and insulating properties. On the other hand, considerable attention is paid to lowering the process temperature to allow coating on plastic substrates because high‐temperature annealing (≈200 °C) is usually required to convert precursors to polyimide films with those excellent properties. In addition, polyimide‐based dielectric films have low dielectric constants (k) (<4). Therefore, modifying the k properties of polyimide is a critical issue for applications as an insulating thin film for practical transistors. This paper reports a new type of polyimide‐based gate dielectric comprising methacryloyl moiety (PI‐MA) as a side chain for photo‐pattern/processability and high‐k properties. This study shows that the photocured PI‐MA thin films show excellent insulating properties (leakage current densities < 10−8 A cm⁻2 at 4 MV cm⁻1) and high‐k properties (≈8) even without a post‐annealing process. Finally, the use of PI‐MA in printed field‐effect transistors results in high performance with low‐voltage operation (within 5 V) and integrated logic‐gate devices (NOT, NAND, and NOR gates). [ABSTRACT FROM AUTHOR]

Homopolymers and alternating copolymers of conjugated molecules exhibit impressive performance in electronic devices. Despite the well‐established procedures, the synthesis of alternating copolymers using three monomers is not as easy as random copolymers. Besides facile synthesis, the random copolymers can match the performance of alternating copolymers in electronic devices. Herein, random copolymers are designed and synthesized comprising thienoisoindigo (TIIG), diketopyrrolopyrrole (DPP), and thiophene. The DPP monomers installed with various side chains including branched alkyl chain, branched alkyl chain with ester functionality, linear oligo ethylene glycol, and siloxane terminated alkyl chain are incorporated into the polymers (P1, P2, P3, and P4, respectively). All the thermally stable, low bandgap random copolymers exhibited strong H‐type aggregation in thin film. The relationship between thin film microstructure originating from diverse side chains and the charge transport in organic field effect transistors (OFETs) is investigated. All the random copolymers exhibited predominantly p‐type charge transport and a maximum hole mobility of 2 × 10−2 cm2 V−1s−1 is observed for P3. The packing of all the polymers is examined theoretically by density functional theory (DFT) and compared with experimental values obtained from grazing incident X‐ray diffraction (GIXRD). [ABSTRACT FROM AUTHOR]

Sol–gel‐based solution‐processed metal oxides have emerged as a key fabrication method for applications in thin film transistors both as a semiconducting and a dielectric layer. Here, a low‐temperature, green solvent‐based, non‐toxic, and cost‐effective solution shearing approach for the fabrication of thin aluminum oxide (AlOx) dielectrics is reported. Optimization of sustainability aspects like energy demand, and selection of chemicals used allows to reduce the environmental impact of the life cycle of the resulting product already in the design phase. Using this approach, ultra‐thin, device‐grade AlOx films of 7 nm are coated—the thinnest films to be reported for any solution‐fabrication method. The metal oxide formation is achieved by both thermal annealing and deep ultra‐violet (UV) light exposure techniques, resulting in capacitances of 750 and 600 nF cm−2, respectively. The structural analysis using microscopy and x‐ray spectroscopy techniques confirmed the formation of smooth, ultra‐thin AlOx films. These thin films are employed in organic field‐effect transistors (OFETs) resulting in stable, low hysteresis devices leading to high mobilities (6.1 ± 0.9 cm2 V−1 s−1), near zero threshold voltage (−0.14 ± 0.07 V) and a low subthreshold swing (96 ± 16 mV dec−1), enabling device operation at only ±0.5 V with a good Ion/Ioff ratio (3.7 × 105). [ABSTRACT FROM AUTHOR]

N‐type organic semiconductors are essential for the advancement of organic electronic devices. However, in relation to extensive research on n‐type and p‐type polymers, studies on high‐mobility n‐type small‐molecule semiconductors (SMSCs) are limited. Here, a series of ultra‐narrow bandgap n‐type SMSCs are developed on an A‐D‐A‐type structure. These SMSCs feature an exceptionally large π‐conjugated area, leading to strong intramolecular charge transfer and robust π‐π interactions. For the first time, central core and terminal halogenation are employed to control molecular surface electrostatic potential distribution, thereby regulating the π‐π stacking area (Sπ‐π) and studying their correlation. The research reveals that, in n‐type SMSCs with an edge‐on arrangement, introducing fluorine into the 2D central core can reduce the Sπ‐π, which is detrimental to the electron mobility (µe) of organic field‐effect transistors (OFETs). Conversely, terminal chlorination facilitates electron injection and improves µe. Consequently, DTPC‐OD‐4Cl, featuring shorter alkyl side chains and a non‐fluorinated 2D central core and undergoing terminal chlorination, achieved the highest µe of up to 0.52 cm2 V−1 s−1, ranking among the highest values reported for A‐D‐A type SMSCs. This work not only systematically investigated the influence of molecular structure on mobility but also provided novel insights for designing more efficient n‐type SMSCs. [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]

Spermidine is an essential biomarker related to antiaging. Although the detection of spermidine levels is in high demand in life science fields, easy‐to‐use analytical tools without sample purification have not yet been fully established. Herein, we propose an organic field‐effect transistor‐based chemical sensor for quantifying the spermidine concentration in commercial cosmetics. An extended‐gate structure was employed for organic field‐effect transistor (OFET)‐based chemical sensing in aqueous media. A coordination‐bond‐based sensing system was introduced into the OFET device to visualize the spermidine detection information through changes in the transistor characteristics. The extended‐gate‐type OFET has shown quantitative responses to spermidine, which indicates sufficient detectability (i. e. the limit of detection for spermidine: 2.3 μM) considering actual concentrations in cosmetics. The applicability of the OFET‐based chemical sensor for cosmetic analysis was validated by instrumental analysis using high‐performance liquid chromatography. The estimated recovery rates for spermidine in cosmetic ingredient products (108–111 %) suggest the feasibility of cosmetic analysis based on the OFET‐based chemical sensor. [ABSTRACT FROM AUTHOR]

Calcium (Ca)-doped zinc oxide (ZnO) with 1 wt.% and 3 wt.% Ca content (CZO_1% and CZO_3%) and pure ZnO (ZO) nanoparticles (NPs) were synthesized using the sol–gel method. The X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) observations showed that calcium was incorporated in the ZnO lattice, the crystallites were nanometric in size, and the obtained NPs were prismatic in shape with sizes ranging from 40 nm to 60 nm agglomerated microspheres. Poly(3-hexylthiophene-2.5-diyl) (P3HT):ZO (PZO_50, PZO_100, and PZO_150), CZO_1% (PCZO1%_50, PCZO1%_100, and PCZO1%_150), and CZO_3% (PCZO3%_50, PCZO3%_100, and PCZO3%_150) blend thin films were prepared at a ratio from 0 mg to 150 mg. The optical characterization carried out on the P3HT:ZO, P3HT:CZO_1%, and P3HT:CZO_3% layers showed that the incorporation of pure and Ca-doped ZnO NPs had a weak influence on the chain structure and the optical gap of P3HT. The direct-bandgap energy varied with doping from 1.85 to 1.89 for ZO, 1.72 eV to 1.83 eV for PCZO_1%, and 1.69 to 1.80 for PCZO_3%. Organic field-effect transistors (OFETs) based on PZO_50, PZO_100, PZO_150, PCZO1%_50, PCZO1%_100, and PCZO1%_150, PCZO3%_50, PCZO3%_100, and PCZO3%_150 thin films used as active layers were successfully fabricated at low temperature. The electrical characterization of the nine OFETs was performed by comparison in ambient air. The results showed that the PCZO1%_150 exhibited better electrical performance, with saturation mobility (μsat) of 1.3 × 10−3 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]

In integrated circuits (ICs), the parasitic capacitance is one of the crucial factors that degrade the circuit dynamic performance; for instance, it reduces the operating frequency of the circuit. Eliminating the parasitic capacitance in organic transistors is notoriously challenging due to the inherent tradeoff between manufacturing costs and interlayer alignment accuracy. Here, we overcome such a limitation using a cost‐effective method for fabricating organic thin‐film transistors and rectifying diodes without redundant electrode overlaps. This is achieved by placing all electrodes horizontally and introducing sub‐100 nm gaps for separation. A representative small‐scale IC consisting of five‐stage ring oscillators based on the obtained nonparasitic transistors and diodes is fabricated on flexible substrates, which performs reliably at a low driving voltage of 1 V. Notably, the oscillator exhibits signal propagation delays of 5.8 μs per stage at a supply voltage of 20 V when utilizing pentacene as the active layer. Since parasitic capacitance has been a common challenge for all types of thin‐film transistors, our approach may pave the way toward the realization of flexible and large‐area ICs based on other emerging and highly performing semiconductors. [ABSTRACT FROM AUTHOR]

Quinoidal small molecule semiconductors hold huge potential in ambipolar organic field-effect transistors (OFETs) and organic spintronic devices. Here, two quinoidal molecules with methylthio side chains were synthesized to develop molecular semiconductors with high ambipolar mobility, designated QBDTS and QTBDTS. The theoretical calculation results reveal that QBDTS has a closed-shell structure while QTBDTS showed an open-shell structure with a biradical character (y0) of 0.46 and its magnetic properties were further investigated using electron paramagnetic resonance (EPR) and superconducting quantum interference device (SQUID) methods. The methyl side chains showed a large impact on the molecular orbital levels. The HOMO/LUMO levels of QBDTS and QTBDTS were measured to be −5.66/−4.56 and −5.27/−4.48 eV, respectively, which are favorable for ambipolar charge transport in OFETs. Importantly, the spin-coated QBDTS displayed hole and electron mobilities of 0.01 and 0.5 cm2 V−1 s−1 while QTBDTS showed a record high hole mobility of 1.8 cm2 V−1 s−1 and electron mobility of 0.3 cm2 V−1 s−1. Moreover, comparative studies of the thin film morphologies also manifested the beneficial influence of methyl side chains on film crystallinity and molecule orientation. These results strongly proved that methyl side chain engineering can be a simple but efficient strategy for modulating electronic properties and molecular stacking behaviors. This work also represents a big advancement for quinoidal molecular semiconductors in ambipolar OFET applications. [ABSTRACT FROM AUTHOR]

The isoindigo and its derivatives have rapidly garnered attention as widely employed electron‐deficient moieties, finding extensive applications in organic field‐effect transistors. In this study, four different isoindigo‐based organic semiconductor polymers were synthesized via a Stille coupling reaction of four isoindigo molecules with varying side chains serving as acceptors and bithiophene as donors. Furthermore, their optical, electrochemical, thermal stability, and other relevant properties were comprehensively evaluated. These polymers exhibited remarkable electrochemical and thermal stability attributed to their low LUMO energy level, which facilitates effective electrical contact between the semiconductor layer and the source/drain while ensuring excellent air stability for the semiconductor polymers. Additionally, solution‐gate field‐effect transistors prepared using these polymers achieved hole mobilities of 10−2 cm2 V−1 S−1 along with an Ion/Ioff ratio of 8.39×103, demonstrating exceptional field‐effect performance. [ABSTRACT FROM AUTHOR]

Inspired by the previous machine‐learning study that the number of hydrogen‐bonding acceptor (NHBA) is important index for the hole mobility of organic semiconductors, seven dithienobenzothiazole (DBT) derivatives 1 a–g (NHBA=5) were designed and synthesized by one‐step functionalization from a common precursor. X‐ray single‐crystal structural analyses confirmed that the molecular arrangements of 1b (the diethyl and ethylthienyl derivative) and 1c (the di(n‐propyl) and n‐propylthienyl derivative) in the crystal are classified into brickwork structures with multidirectional intermolecular charge‐transfer integrals, as a result of incorporation of multiple hydrogen‐bond acceptors. The solution‐processed top‐gate bottom‐contact devices of 1b and 1c had hole mobilities of 0.16 and 0.029 cm2 V−1s−1, respectively. [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]

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]

Unipolar p‐ and n‐type organic field‐effect transistors (OFETs) are essential for constructing organic circuits and complementary designs crucial for high‐performance electronics. Traditionally, fabricating these transistors requires separate p‐type and n‐type organic semiconductors (OSCs), which complicates the process due to intricate patterning, protection of the first OSC layer, and considerable material wastage. In this work, an innovative approach is introduced, inspired by silicon transistor fabrication to obtain unipolar OFETs, employing a single ambipolar OSC in conjunction with doped organic semiconductor films (DOSCFs) as electrodes. This results demonstrate that OFETs with DOSCF electrodes suppress ambipolarity dramatically and achieve on/off ratios that are two to three orders of magnitude higher than those with metal electrodes, along with excellent stability. The unipolar characteristics of the devices are attributed to the unique work function properties and the intrinsic charge carrier behavior of the DOSCF electrodes. Significantly, inverter circuits utilizing these unipolar transistors outperformed traditional ambipolar transistors with metal electrodes, achieving a fivefold increase in voltage gain. This novel strategy promises to enhance the practicality and economic viability of organic electronics, paving the way for more sustainable and high‐performance circuit designs. [ABSTRACT FROM AUTHOR]

Developing novel n‐type organic semiconductors is an on‐going research endeavour, given their pivotal roles in organic electronics and their relative scarcity compared to p‐type counterparts. In this study, a new strategy was employed to synthesize n‐type organic semiconductors featuring a fully fused conjugated backbone. By attaching two sets of adjacent amino and formyl groups to the indacenodithiophene‐based central cores and triggering a tandem reaction sequence of a Knoevenagel condensation‐intramolecular cyclization, DFA1 and DFA2 were realized. The solution‐processed organic field effect transistors based on DFA1 exhibited unipolar n‐type transport character with a decent electron mobility of ca. 0.10 cm2 V−1 s−1 (ca. 0.038 cm2 V−1 s−1 for DFA2 based devices). When employing DFA1 as a third component in organic solar cells, a high power conversion efficiency of 19.2 % can be achieved in ternary devices fabricated with PM6 : L8‐BO : DFA1. This work provides a new pathway in the molecular engineering of n‐type organic semiconductors, propelling relevant research forward. [ABSTRACT FROM AUTHOR]