Easily processable phenylene-thiophene-based organic field-effect transistors and solution-fabricated nonvolatile transistor memory elements

Supramolecular Transistors with Quantum Interference Effect

The charge transport through supramolecular junctions exhibits unique quantum interference (QI) effects, which provide an opportunity for the design of supramolecular transistors. Benefiting from the configuration dependence of QI, configuration control of the supramolecular assemblies to demonstrate the QI features is a key but challenging step. In this work, we fabricated the supramolecular transistors and investigated the charge transport through the conducting channel of the individual π-stacked thiophene/phenylene co-oligomers (TPCOs) using the electrochemically gated scanning tunneling microscope break junction technique. We controlled the configuration of the supramolecular channel and switched the QI features between the anti-resonance and resonance states of the supramolecular channels. We observed the supramolecular transistor with its on/off ratio above 103 (∼1300), a high gating efficiency of ∼165 mV/dec, a low off-state leakage current of ∼30 pA, and the channel length scaled down to <2.0 nm. Density functional theory calculations suggested that the QI features in π-stacked TPCOs vary depending on the supramolecular architecture and can be manipulated efficiently by fine-tuning the supramolecular configurations. This work reveals the potential of the supramolecular channels for molecular electronics and provides a fundamental understanding of intermolecular charge transport.

Impact of Planar and Vertical Organic Field-Effect Transistors on Flexible Electronics

The development of flexible and conformable devices, whose performance can be maintained while being continuously deformed, provides a significant step toward the realization of next-generation wearable and e-textile applications. Organic field-effect transistors (OFETs) are particularly interesting for flexible and lightweight products, because of their low-temperature solution processability, and the mechanical flexibility of organic materials that endows OFETs the natural compatibility with plastic and biodegradable substrates. Here, an in-depth review of two competing flexible OFET technologies, planar and vertical OFETs (POFETs and VOFETs, respectively) is provided. The electrical, mechanical, and physical properties of POFETs and VOFETs are critically discussed, with a focus on four pivotal applications (integrated logic circuits, light-emitting devices, memories, and sensors). It is pointed out that the flexible function of the relatively newer VOFET technology, along with its perspective on advancing the applicability of flexible POFETs, has not been reviewed so far, and the direct comparison regarding the performance of POFET- and VOFET-based flexible applications is most likely absent. With discussions spanning printed and wearable electronics, materials science, biotechnology, and environmental monitoring, this contribution is a clear stimulus to researchers working in these fields to engage toward the plentiful possibilities that POFETs and VOFETs offer to flexible electronics.

Mixed Ionic and Electronic Conduction in Small-Molecule Semiconductors

Small-molecule organic semiconductors have displayed remarkable electronic properties with a multitude of π-conjugated structures developed and fine-tuned over recent years to afford highly efficient hole- and electron-transporting materials. Already making a significant impact on organic electronic applications including organic field-effect transistors and solar cells, this class of materials is also now naturally being considered for the emerging field of organic bioelectronics. In efforts aimed at identifying and developing (semi)conducting materials for bioelectronic applications, particular attention has been placed on materials displaying mixed ionic and electronic conduction to interface efficiently with the inherently ionic biological world. Such mixed conductors are conveniently evaluated using an organic electrochemical transistor, which further presents itself as an ideal bioelectronic device for transducing biological signals into electrical signals. Here, we review recent literature relevant for the design of small-molecule mixed ionic and electronic conductors. We assess important classes of p- and n-type small-molecule semiconductors, consider structural modifications relevant for mixed conduction and for specific interactions with ionic species, and discuss the outlook of small-molecule semiconductors in the context of organic bioelectronics.

Effect of substituting non-polar chains with polar chains on the structural dynamics of small organic molecule and polymer semiconductors

The processability and optoelectronic properties of organic semiconductors can be tuned and manipulated via chemical design. The substitution of the popular alkyl side chains by oligoethers has recently been successful for applications such as bioelectronic sensors and photocatalytic hydrogen evolution. Beyond the differences in polarity, the carbon-oxygen bond in oligoethers is likely to render the system softer and more prone to dynamical disorder that can be detrimental to charge transport for example. In this context, we use neutron spectroscopy as a master method of probe, in addition to characterisation techniques such as X-ray diffraction, differential scanning calorimetry and polarized optical microscopy to study the effect of the substitution of n-hexyl (Hex) chains by triethylene glycol (TEG) chains on the structural dynamics of two organic semiconducting materials: a phenylene-bithiophene-phenylene (PTTP) small molecule and a fluorene-co-dibenzothiophene (FS) polymer. Counterintuitively, inelastic neutron scattering (INS) reveals a general softening of the modes of PTTP and FS materials with Hex chains, pointing towards an increased dynamical disorder in the Hex-based systems. However, temperature-dependent X-ray and neutron diffraction as well as INS and differential scanning calorimetry evidence an extra reversible transition close to room temperature for PTTP with TEG chains. The observed extra structural transition, which is not accompanied by a change in birefringence, can also be observed by quasi-elastic neutron scattering (QENS). A fastening of the TEG chains dynamics is observed in the case of PTTP and not FS. We therefore assign this transition to the melt of the TEG chains. Overall the TEG chains are promoting dynamical order at room temperature, but if crystallising, may introduce an extra reversible structural transition above room temperature leading to thermal instabilities. Ultimately, a deeper understanding of chain polarity and structural dynamics can help guide new materials design and navigate the intricate balance between electronic charge transport and aqueous swelling that is being sought for a number of emerging organic electronic and bioelectronic applications.

A Conjugated Polymer Containing Arylazopyrazole Units in the Side Chains for Field-Effect Transistors Optically Tunable by Near Infra-Red Light

Optically tunable field-effect transistors (FETs) with near infra-red (NIR) light show promising applications in various areas. Now, arylazopyrazole groups are incorporated in the side chains of a semiconducting donor-acceptor (D-A) polymer. The cis-trans interconversion of the arylazopyrazole can be controlled by 980 nm and 808 nm NIR light irradiation, by utilizing NaYF₄ :Yb,Tm upconversion nanoparticles and the photothermal effect of conjugated D-A polymers, respectively. This reversible transformation affects the interchain packing of the polymer thin film, which in turn reversibly tunes the semiconducting properties of the FETs by the successive 980 nm and 808 nm light irradiation. The resultant FETs display fast response to NIR light, good resistance to photofatigue, and stability in storage for up to 120 days. These unique features will be useful in future memory and bioelectronic wearable devices.

When Flexible Organic Field-Effect Transistors Meet Biomimetics: A Prospective View of the Internet of Things

The emergence of flexible organic electronics that span the fields of physics and biomimetics creates the possibility for increasingly simple and intelligent products for use in everyday life. Organic field-effect transistors (OFETs), with their inherent flexibility, light weight, and biocompatibility, have shown great promise in the field of biomimicry. By applying such biomimetic OFETs for the internet of things (IoT) makes it possible to imagine novel products and use cases for the future. Recent advances in flexible OFETs and their applications in biomimetic systems are reviewed. Strategies to achieve flexible OFETs are individually discussed and recent progress in biomimetic sensory systems and nervous systems is reviewed in detail. OFETs are revealed to be one of the best systems for mimicking sensory and nervous systems. Additionally, a brief discussion of information storage based on OFETs is presented. Finally, a personal view of the utilization of biomimetic OFETs in the IoT and future challenges in this research area are provided.

Oligothiophene Synthesis by a General C-H Activation Mechanism: Electrophilic Concerted Metalation-Deprotonation (eCMD)

Oxidative C-H/C-H coupling is a promising synthetic route for the streamlined construction of conjugated organic materials for optoelectronic applications. Broader adoption of these methods is nevertheless hindered by the need for catalysts that excel in forging core semiconductor motifs, such as ubiquitous oligothiophenes, with high efficiency in the absence of metal reagents. We report a (thioether)Pd-catalyzed oxidative coupling method for the rapid assembly of both privileged oligothiophenes and challenging hindered cases, even at low catalyst loading under Ag- and Cu-free conditions. A combined experimental and computational mechanistic study was undertaken to understand how a simple thioether ligand, MeS(CH₂)₃SO₃Na, leads to such potent reactivity toward electron-rich substrates. The consensus from these data is that a concerted, base-assisted C-H cleavage transition state is operative, but thioether coordination to Pd is associated with decreased synchronicity (bond formation exceeding bond breaking) versus the "standard" concerted metalation-deprotonation (CMD) model that was formalized by Fagnou in direct arylation reaction. Enhanced positive charge build-up on the substrate results from this perturbation, which rationalizes experimental trends strongly favoring π-basic sites. The term electrophilic CMD (eCMD) is introduced to distinguish this mechanism from the standard model, even though both mechanisms locate in a broad concerted continuum. More O'Ferrall-Jencks analysis further suggests eCMD should be a general mechanism manifested by many metal complexes. A preliminary classification of complexes into those favoring eCMD or standard CMD is proposed, which should be informative for studies toward tunable catalyst-controlled reactivity.

Pursuing Polymer Dielectric Interfacial Effect in Organic Transistors for Photosensing Performance Optimization

Polymer dielectrics in organic field-effect transistors (OFETs) are essential to provide the devices with overall flexibility, stretchability, and printability and simultaneously introduce charge interaction on the interface with organic semiconductors (OSCs). The interfacial effect between various polymer dielectrics and OSCs significantly and intricately influences device performance. However, understanding of this effect is limited because the interface is buried and the interfacial charge interaction is difficult to stimulate and characterize. Here, this challenge is overcome by utilizing illumination to stimulate the interfacial effect in various OFETs and to characterize the responses of the effect by measuring photoinduced changes of the OFETs performances. This systemic investigation reveals the mechanism of the intricate interfacial effect in detail, and mathematically explains how the photosensitive OFETs characteristics are determined by parameters including polar group of the polymer dielectric and the OSC side chain. By utilizing this mechanism, performance of organic electronics can be precisely controlled and optimized. OFETs with strong interfacial effect can also show a signal additivity caused by repeated light pulses, which is applicable for photostimulated synapse emulator. Therefore, this work enlightens a detailed understanding on the interface effect and provides novel strategies for optimizing OFET photosensory performances.

Direct Detection of Dilute Solid Chemicals with Responsive Lateral Organic Diodes

Organic field-effect transistors (OFETs) have emerged as promising sensors targeting chemical analytes in vapors and liquids. However, the direct detection of solid chemicals by OFETs has not been achieved. Here for the first time, we describe the direct detection of solid chemical analytes by organic electronics. An organic diode structure based on a horizontal side-by-side p-n junction was adopted and shown to be superior to OFETs for this purpose. The diodes showed more than 40% current decrease upon exposure to 1 ppm melamine powders. The estimated detection limit to melamine can potentially reach the ppb range. This is the first demonstration of an electronic signal from an interaction between a solid and an organic p-n junction directly, which suggests that our lateral organic diodes are excellent platforms for the development of future sensors when direct detection of solid chemicals is needed. The approach developed here is general and can be extended to chemical sensors targeting various analytes, opening unprecedented opportunities for the development of low-cost and high-performance solid chemical sensors.

Chain Length Dependence of the Dielectric Constant and Polarizability in Conjugated Organic Thin Films

Dielectric materials are ubiquitous in optics, electronics, and materials science. Recently, there have been new efforts to characterize the dielectric performance of thin films composed of molecular assemblies. In this context, we investigate here the relationship between the polarizability of the constituent molecules and the film dielectric constant, using periodic density functional theory (DFT) calculations, for polyyne and saturated alkane chains. In particular, we explore the implication of the superlinear chain length dependence of the polarizability, a specific feature of conjugated molecules. We show and explain from DFT calculations and a simple depolarization model that this superlinearity is attenuated by the collective polarization. However, it is not completely suppressed. This confers a very high sensitivity of the dielectric constant to the thin film thickness. This latter can increase by a factor of 3-4 at reasonable coverages, by extending the molecular length. This significantly limits the decline of the thin film capacitance with the film thickness. Therefore, the conventional fit of the capacitance versus thickness is not appropriate to determine the dielectric constant of the film. Finally, we show that the failures of semilocal approximations of the exchange-correlation functional lead to a very significant overestimation of this effect.

Epitaxial Growth of MOF Thin Film for Modifying the Dielectric Layer in Organic Field-Effect Transistors

Metal-organic framework (MOF) thin films are important in the application of sensors and devices. However, the application of MOF thin films in organic field effect transistors (OFETs) is still a challenge to date. Here, we first use the MOF thin film prepared by a liquid-phase epitaxial (LPE) approach (also called SURMOFs) to modify the SiO₂ dielectric layer in the OFETs. After the semiconductive polymer of PTB7-Th (poly[4,8-bis(5-(2-ethylhexyl)thiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]) was coated on MOF/SiO₂ and two electrodes on the semiconducting film were deposited sequentially, MOF-based OFETs were fabricated successfully. By controlling the LPE cycles of SURMOF HKUST-1 (also named Cu₃(BTC)₂, BTC = 1,3,5-benzenetricarboxylate), the performance of the HKUST-1/SiO₂-based OFETs showed high charge mobility and low threshold voltage. This first report on the application of MOF thin film in OFETs will offer an effective approach for designing a new kind of materials for the OFET application.

α-Amino Thiophene on Si(100)2 × 1: Adsorption and transition states investigated by van der Waals corrected DFT and CI-NEB

The adsorption of [Formula: see text]-AminoTiophene on Si(100)2[Formula: see text][Formula: see text][Formula: see text]1 was investigated by van der Waals corrected DFT and climbing image nudged-elastic band, in view of potential applications in silicon-based technologies. The overall scenario indicates that dissociative states are more favorable than the molecular ones, the one occurring through N–C bond breakage and Si–N and Si–C bond formation, having the largest adsorption energy (2.71[Formula: see text]eV). Furthermore, this configuration is also kinetically easily accessible, being connecting to one of the physisorbed states (Phys1) by a nearly barrierless transition. Also the molecular states are relatively easily kinetically accessible, with transition barriers from the corresponding physisorbed states in the 0.05–0.30[Formula: see text]eV range. At variance with this, the transitions to the dissociative state characterized by N–H bond breakage and Si–N and Si–H bond formation (N–H Diss) either from physisorbed or from molecular states are all significantly higher, i.e. in the 0.63–2.70[Formula: see text]eV range. Finally, the effects of the coverage on the adsorption energy were evaluated for the N–H Diss configuration and indicating a gain, whose extent depends both on the coverage and on the surface arrangement, i.e. whether cis or trans. The trend is different if the vdW forces are excluded.

Green Synthesis of Halogenated Thiophenes, Selenophenes and Benzo[b]selenophenes Using Sodium Halides as a Source of Electrophilic Halogens

Herein, we report the first synthesis of chlorinated benzo[b]selenophenes via environmentally friendly electrophilic chlorocyclization reaction using "table salt" as a source of "electrophilic chlorine" and ethanol as a solvent. In addition, the synthesis of diverse halogenated heterocycles, including 3-chloro, 3-bromo and 3-iodo thiophenes, selenophenes, and benzo[b]selenophenes was successfully accomplished under the same environmentally benign reaction conditions. This methodology has several advantages over other previously reported reactions as it employs simple starting compounds, an environmentally friendly solvent, ethanol, and non-toxic inorganic reagents under mild reaction conditions, resulting in the high product yields.

LED based on alternating benzene-furan oligomers

A series of conjugated-chain compounds which contain two furan units and more than three other aromatic ring units were synthesized by two different methods, their UV-visible absorption coefficient (ε), maximum absorption wavelengths (λa), fluorescence emission wavelengths (λe), stokes shift and quantum yields (Φ) were determined, the relationships between the molecular structures and the effects of spectral behaviors were discussed. Meanwhile, the excitation spectrum and emission spectrum of 2b and 2d in solid and in ethyl acetate were respectively recorded, the thermal stability of 2b and 2d was evaluated, and the fluorescence emission behaviors of two light emitting diodes, fabricated with 2b and 2d as phosphors, were investigated. The results showed that most of target compounds can perform high fluorescence emission ability, compounds 2b and 2d can perform higher thermal stability under 350°C and they are suitable for making light emitting diode as phosphors, the light emitting diodes fabricated with 2b and 2d can show higher fluorescence emission ability. Therefore, those compounds are worthy of further being developed as fluorescent emission materials.

Regular and red-shifted fluorescence of the donor–acceptor compound 5-(1H-pyrrole-1-yl)thiophenecarbonitrile (TCN) is efficiently quenched by internal modes of thiophene

The photochemical properties of thiophene analogs of N-pyrrolobenzonitrile (PBN), notably the two isomers 5-(1H-pyrrole-1-yl)thiophene-2-carbonitrile (2-TCN) and 5-(1H-pyrrole-1-yl)thiophene-3-carbonitrile (3-TCN) have been investigated.

Polymer Nanodot-Hybridized Alkyl Silicon Oxide Nanostructures for Organic Memory Transistors with Outstanding High-Temperature Operation Stability

Organic memory devices (OMDs) are becoming more important as a core component in flexible electronics era because of their huge potentials for ultrathin, lightweight and flexible plastic memory modules. In particular, transistor-type OMDs (TOMDs) have been gradually spotlighted due to their structural advantages possessing both memory and driving functions in single devices. Although a variety of TOMDs have been developed by introducing various materials, less attention has been paid to the stable operation at high temperatures. Here we demonstrate that the polymer nanodot-embedded alkyl silicon oxide (ASiO) hybrid materials, which are prepared by sol-gel and thermal cross-linking reactions between poly(4-vinylphenol) (PVP) and vinyltriethoxysilane, can deliver low-voltage (1~5 V) TOMDs with outstanding operation stability (>4700 cycles) at high temperatures (150 °C). The efficient low-voltage memory function is enabled by the embedded PVP nanodots with particular lattice nanostructures, while the high thermal stability is achieved by the cross-linked ASiO network structures.

Design of a Photoactive Hybrid Bilayer Dielectric for Flexible Nonvolatile Organic Memory Transistors

Organic field-effect transistors (OFETs) featuring a photoactive hybrid bilayer dielectric (PHBD) that comprises a self-assembled monolayer (SAM) of photochromic diarylethenes (DAEs) and an ultrathin solution-processed hafnium oxide layer are described here. We photoengineer the energy levels of DAE SAMs to facilitate the charging and discharging of the interface of the two dielectrics, thus yielding an OFET that functions as a nonvolatile memory device. The transistors use light signals for programming and electrical signals for erasing (≤3 V) to produce a large, reversible threshold-voltage shift with long retention times and good nondestructive signal processing ability. The memory effect can be exercised by more than 10(4) memory cycles. Furthermore, these memory cells have demonstrated the capacity to be arrayed into a photosensor matrix on flexible plastic substrates to detect the spatial distribution of a confined light and then store the analog sensor input as a two-dimensional image with high precision over a long period of time.

Organic Electronic Memory Devices

With the rapid development of the electronics industry in recent years, information technology devices, such as personal computers, mobile phones, digital cameras and media players, have become an essential part of our daily life. From both the technological and economic points of view, the development of novel information storage materials and devices has become an emergent issue facing the electronics industry. Due to the advantages of good scalability, flexibility, low cost, ease of processing, 3D-stacking capability and high capacity for data storage, organic-based electrical memory devices have been promising alternatives or supplementary devices to conventional inorganic semiconductor-based memory technology. The basic concepts and historical development of electronic memory devices are first presented. The following section introduces the structures and switching mechanisms of organic electronic memory devices classified as transistors, capacitors and resistors. Subsequently, the progress in the field of organic-based memory materials and devices is systematically summarized and discussed. Finally, the challenges posed to the development of novel organic electronic memory devices are summarized.

Interfacing Solution-Grown C60 and (3-Pyrrolinium)(CdCl3 ) Single Crystals for High-Mobility Transistor-Based Memory Devices

Aligned ferroelectric single crystals of (3-pyrrolinium)(CdCl₃ ) can be prepared from solution on top of aligned semiconducting C₆₀ single crystals using an orthogonal solvent. Memory devices based on these ferroelectric/semiconductor bilayered heterojunctions exhibit much larger hysteresis compared with that of only C₆₀ single crystals. More importantly, the introduction of the ferroelectric layer induces the memory window without dramatically reducing the charge mobility.

The ratio and topology effects of benzodithiophene donor-benzooxadiazole acceptor fragments on the optoelectronic properties of donor molecules toward solar cell materials

A series of conjugated donor molecules (DmAnSq where m = 1-4, n = 1-7 while D = benzodithiophene, A = benzooxadiazole and S denotes ethyne spacers between D and A or D and D fragments) with various ratios of D/A fragments and topologies have been designed and investigated for OPV applications. An increase in the ratio of the acceptor fragment with respect to the donor fragment decreases the LUMO energy level and narrows the Eg for the designed molecule. More vertically (C4 and C8 substituted phenyl ring positions) bonded acceptor fragments than linearly (C2 and C6 substituted thiophene ring positions) bonded fragments result in a significant red shift in the maximum absorption wavelength. While, linearly bonded fragments lead to stronger absorption bands. Molecules with D-A-D topology exhibit more significant optical and electronic characteristics than those with D-D topology. All donor molecules (m = 2-4) of the D-A-D type show lower λh values than those of 1 donor containing (DAn) molecules. D-D type molecules show only lower λe values than DAn molecules because of the presence of a second donor fragment. The charge transfer phenomenon is shape dependent. The branched or anisotropic X, H, π, n, and square shaped molecules display higher charge transfer rates than the corresponding linear isomers due to better dimensionality. On the basis of these results, we suggest that designed donor and corresponding matched acceptor molecules have potential to act as promising candidates in solar cell devices.

Vibrational spectroscopic, NMR parameters and electronic properties of three 3-phenylthiophene derivatives via density functional theory

Quantum chemistry calculations have been performed to compute the optimized geometries, vibrational frequencies, and Mulliken Charges at B3LYP/6-31G(d) and B3LYP/6-311++G(d,p) levels for 3-(4-fluorophenyl)thiophene (FPT), 3-(4-nitrophenyl)thiophene (NPT) and 3-(4-cyanophenyl) thiophene (CPT) in the ground state. In addition, the ¹³C and ¹H NMR are calculated by B3LYP/6-311++G(d,p) and B3LYP/6-311++G(2d,2p) methods. The singlet electronic excited state properties of the three compounds were investigated using the time-dependent density functional method (TD-DFT) at the B3LYP/6-311++G(d,p)//TD- B3LYP/6-311++G(d,p) level of theory. The influence of the substituted groups on C9 atom is discussed.

Solution processable benzooxadiazole and benzothiadiazole based D-A-D molecules with chalcogenophene: field effect transistor study and structure property relationship

We present here the physicochemical characterization of a series of D-A-D type molecules which comprise benzooxadiazole (BDO) and benzothiadiazole (BDT) core symmetrically linked to two aromatic-heterols (furan (F), thiophene (T) and selenophene (Se)) at 4 and 7-positions. The molecular structures of four compounds 2 (T-BDO-T), 3 (Se-BDO-Se), 5 (T-BDT-T), and 6 (Se-BDT-Se) were determined by single-crystal X-ray diffraction. The combination of chalcogen atoms of benzochalcogenadiazole and chalcogenophene in D-A-D molecules has significant impact on their molecular packing in crystal structures. Structural analyses and theoretical calculations showed that all the molecules are nearly planar. Crystal structures of 2, 3, 5, and 6 showed significant short range interactions such as π···π, CH···π, S···π, Se···π, N···H, O···H, S···H, Se···H, S···O, and Se···N interactions, which influence crystal packing and orientation of the capped aromatic-heterol rings with respect to the central BDO or BDT unit. The π-stacking interactions have been observed via intermolecular overlap of the donor with acceptor units of the adjacent molecules which facilitate the charge transport process. Good thermal stability and solubility in common organic solvents make them good candidate for flexible electronics. Interestingly, the molecules 2, 3, and 6 have the propensity to form ordered crystallites when sheared during the drying process in the thin films. Devices based on these solution processable all organic FETs demonstrated hole mobility as high as 0.08 cm(2) V(-1) s(-1) and Ion/Ioff ratio of 10(4).

C-H bond activation enables the rapid construction and late-stage diversification of functional molecules

The beginning of the twenty-first century has witnessed significant advances in the field of C-H bond activation, and this transformation is now an established piece in the synthetic chemists' toolbox. This methodology has the potential to be used in many different areas of chemistry, for example it provides a perfect opportunity for the late-stage diversification of various kinds of organic scaffolds, ranging from relatively small molecules like drug candidates, to complex polydisperse organic compounds such as polymers. In this way, C-H activation approaches enable relatively straightforward access to a plethora of analogues or can help to streamline the lead-optimization phase. Furthermore, synthetic pathways for the construction of complex organic materials can now be designed that are more atom- and step-economical than previous methods and, in some cases, can be based on synthetic disconnections that are just not possible without C-H activation. This Perspective highlights the potential of metal-catalysed C-H bond activation reactions, which now extend beyond the field of traditional synthetic organic chemistry.

Multi-functional integration of organic field-effect transistors (OFETs): advances and perspectives

Multi-functional organic field-effect transistors (OFETs), an emerging focus of organic optoelectronic devices, hold great potential for a variety of applications. This report introduces recent progress on multi-functional OFETs including OFETs based sensors, phototransistors, light-emitting transistors, memory cells, and magnetic field-effect OFETs. Key strategies towards multi- functional integration of OFETs, which involves the exploration of functional materials, interfaces modifications, modulation of condensed structures, optimization of device geometry, and device integration, are summarized. Furthermore, remaining challenges and perspectives are discussed, giving a comprehensive overview of multi-functional OFETs.

Theoretical study of phenylene-thiophene oligomers: structure-properties relationship

Theoretical results including geometrical characteristics, electronic structures, photophysical parameters (lowest excitation energies, electron affinities (EAs), ionization potentials (IPs), maximum of absorption and emission) and vibrational modes of some new oligomers, based on phenylene-thiophene motives, are investigated using Density Functional Theory DFT/B3LYP/6-31G(d) approach. The electronic and optical properties of phenylene-based derivatives can be tuned through the insertion of thiophene in the main oligomers backbone as well as the addition of alkoxy-substituent groups on 2 and 5 positions on phenylene groups. It can be noticed, that different conformational behaviors and steric effects take place. Then, an increase in conjugation length induces a decrease in the gaps energy and a bathochromic shift of absorption/emission spectra. Based on these computed results, which are consistent with the available experimental data, the correlation structure-properties is better understood, where these nanostructures show a great potential for opto-electronic devices.