Search

In the development of flexible organic field-effect transistors (OFET), downsizing and reduction of the operating voltage are essential for achieving a high current density with a low operating power. Although the bias voltage of the OFETs can be reduced by a high-k dielectric, achieving a threshold voltage close to zero remains a challenge. Moreover, the scaling down of OFETs demands the use of photolithography, and may lead to compatibility issues in organic semiconductors. Herein, a new strategy based on the ductile properties of organic semiconductors is developed to control the threshold voltage at close to zero while concurrently downsizing the OFETs. The OFETs are fabricated on prestressed polystyrene shrink film substrates at room temperature, then thermal energy (160 °C) is used to release the strain. The OFETs conformally attached to the wrinkled structure are shown to locally amplify the electric field. After shrinking, the horizontal device area is reduced by 75%, and the threshold voltage is decreased from -1.44 to -0.18 V, with a subthreshold swing of 74 mV dec -1 and intrinsic gain of 4.151 × 10 4 . These results reveal that the shrink film can be generally used as a substrate for downsizing OFETs and improving their performance., (© 2021 Wiley-VCH GmbH.)

Tuning of the energetic barriers to charge transfer at the semiconductor/dielectric interface in organic field-effect transistors (OFETs) is achieved by varying the dielectric functionality. Based on this, the correlation between the magnitude of the energy barrier and the gate-bias stress stability of the OFETs is demonstrated, and the origin of the excellent device stability of OFETs employing fluorinated dielectrics is revealed., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this article, a versatile 2-D conjugated polymer, PNDTP-DPP, containing alkylphenyl substituted naphthodithiophene is synthesized and characterized. PNDTP-DPP exhibits good solubility and crystallinity with a π-π stacking distance of ≈3.7 Å. Investigation of polymer solar cells (PSCs) and organic field-effect transistors (OFET) demonstrates a promising power conversion efficiency (PCE) of 4.11% and a high hole mobility of up to 0.86 cm(2) V(-1) s(-1) , so this is one of the few examples of versatile polymers that show both good field-effect mobility and PCE., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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]

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]

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]

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]

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]

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

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

In state‐of‐the‐art organic transistors, the transit frequency fT is reported to be fT = 40 MHz for vertical organic transistors, where a voltage‐normalized fT corresponds to 0.36 MHz V−2. The reported highest fT for conventional organic transistors is fT = 160 MHz, where the voltage‐normalized fT is 0.1 MHz V−2. While the reported transit frequency fT of n‐MOSFETs for silicon technology when normalized by the applied biases exceeds 300 GHz V−2. The reported carrier mobility of organic semiconductors is over 100 cm2 V−1 s−1, which is almost an order of magnitude lower than that of silicon. However, the transit frequency fT of organic transistors lags far behind silicon technology by about six orders of magnitude at a comparable device length below 300 nm. In this work, a technology computer‐aided design (TCAD) simulator is adjusted to the experimental DC and AC characteristics of the 200 nm device length vertical organic permeable‐base transistors (OPBTs) based on C60 as semiconductor. The AC performance of the devices is investigated and quantitatively analyzed the influence and contribution of key design, structure and material parameters that determine fT and fmax. The feasible ways to enhance and optimize the highest achievable fT and fmax are identified to reach the GHz−range$\rm GHz-range$ and overcome the limitations to high‐frequency operation in organic transistors. [ABSTRACT FROM AUTHOR]

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

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

In recent decades, polymer semiconductors, extensively employed as charge transport layers in devices like organic field‐effect transistors (OFETs), have undergone thorough investigation due to their capacity for large‐area solution processing, making them promising for mass production. Research efforts have been twofold: enhancing the charge mobilities of polymer semiconductors and augmenting their mechanical properties to meet the demands of flexible devices. Significant progress has been made in both realms, propelling the practical application of polymer semiconductors in flexible electronics. However, integrating excellent semiconducting and mechanical properties into a single polymer still remains a significant challenge. This review intends to introduce the design strategies and discuss the properties of high‐charge mobility stretchable conjugated polymers. In addition, another key challenge faced in this cutting‐edge field is maintaining stable semiconducting performance during long‐term mechanical deformations. Therefore, this review also discusses the development of healable polymer semiconductors as a promising avenue to improve the lifetime of stretchable device. In conclusion, challenges and outline future research perspectives in this interdisciplinary field are highlighted. [ABSTRACT FROM AUTHOR]

Recent advances in fabricating field-effect transistors with MoS2 and other related two-dimensional (2D) semiconductors have inspired the industry to begin with the integration of these emerging technologies into FAB-compatible process flows. Just like in the lab research on 2D devices performed in the last decade, focus during development is typically put on pure technology-related issues, such as low-temperature growth methods of large-area 2D films on target substrates, damage-free transfer from sacrificial substrates and growth of top-gate oxides. With maturing technology, the problem of stability limitations caused by oxide traps is gradually coming into focus now. Thus, here we report an in-depth analysis of hysteresis and bias-temperature instabilities for MoS2 FETs fabricated using a 300 mm FAB-compatible process. By performing a comprehensive statistical analysis on devices with top gate lengths ranging between 18 nm and 10 μm, we demonstrate that aggressive scaling results in additional stability problems, likely caused by defective edges of the scaled top gates, in particular at higher operation temperatures. These are important insights for understanding and addressing the stability limitations in future nanoscale 2D FETs produced using FAB process lines. [ABSTRACT FROM AUTHOR]

The accounting method for influence of the collisional broadening of electron quantum states in one-dimensional electron gas on the dispersion law and electron scattering rates for elastic and inelastic mechanisms has been developed in the framework of single-particle approximation of electron ensemble description. In contrast to more rigorous methods the proposed approximation allows analytical expressions for all the relations between charge carriers momentum, energy and group velocity, as well as their scattering rates to be obtained. The application of the proposed approximation in Monte Carlo simulation of charge carrier transport and scattering in device structures on the basis of quantum conductors with one-dimensional electron gas enables cardinal reduction of the computational complexity of corresponding simulation of the particle ensemble behavior. The numerical optimization of physico-topological parameters of vertical ballistic field-effect nanotransistor on the basis of cylindrical undoped AlxGa1–xAs quantum wire standing in Al2O3 matrix surrounded by metallic gate has been realized. Calculation of the current–voltage characteristics of the nanotransistor has been performed in the framework of Landauer-Buttiker formalism based on the transfer matrix approach with account of nonparabolicity of the band structure of simulated conducting semiconductor channel of the transistor. The influence of scattering of electrons by acoustic and polar optical phonons on charge carrier transport outside and above the potential barrier in the transistor channel has been taken into account by means of application of Monte Carlo method. [ABSTRACT FROM AUTHOR]

Despite having an asymmetric structure, 2‐(thiopyran‐4‐ylidene)‐1,3‐benzodithiole (TP‐BT) is a good p‐type semiconductor containing isotropic three‐dimensional (3D) intermolecular interactions. Moreover, its π‐extended analogs can potentially work as organic electronic materials. Herein, a fused‐type π‐extended analog containing an extra benzene ring on the benzodithiole unit, i. e. 2‐(thiopyran‐4‐ylidene)‐1,3‐naphtho[2,3‐d]dithiole (TP‐NT), and three σ‐bonded‐type π‐extended analogs, i. e. phenyl‐, naphthyl‐, and anthryl‐substituted analogs (Ph‐TP‐BT, Nap‐TP‐BT, and Ant‐TP‐BT, respectively), were prepared and their molecular arrangements and organic field‐effect transistor (OFET) properties were investigated. TP‐NT formed a herringbone arrangement with 3D intermolecular interactions similar to that of the parent TP‐BT. Meanwhile, Ant‐TP‐BT formed a bilayer‐type layered herringbone arrangement. Since the highest occupied molecular orbital and the lowest unoccupied molecular orbital are located on the TP‐BT and anthracene units, respectively, a unique donor–acceptor separated network was formed. In OFETs prepared via a vapor deposition method using the σ‐bonded‐type analogs, slightly lower mobilities (0.1 to 8×10−3 cm2/Vs) than that of TP‐NT (0.1 cm2/Vs) were observed. Upon photo‐irradiation, the OFET of Ant‐TP‐BT exhibited a larger threshold voltage shift and an increase in the off current compared with TP‐NT. The σ‐bonded‐type analogs showed a larger photo‐response effect than TP‐NT derived from the donor–acceptor molecular structure. [ABSTRACT FROM AUTHOR]

CdxZn1−xTeySe1−y (CZTS) has emerged as a next-generation compound semiconductor for high energy gamma-ray detection. In the present study, we report for the first time the hole transport property measurements in CZTS based gamma-ray detectors in the planar configuration. Current–voltage measurements revealed a bulk resistivity of ∼5 × 108 Ω cm and the fabricated detectors produced well-resolved 5486 keV alpha particle peaks, for both electrons and holes drifting alike, when pulse-height spectra (PHS) were recorded using a 241Am radiation source. The PHS measurements were enabled to measure the charge transport properties for both the charge carriers. The mobility–lifetime product (μτ) for electrons and holes was calculated to be 6.4 × 10−4 cm2 V−1 and 8.5 × 10−5 cm2 V−1, respectively, using a single polarity Hecht plot regression method. The pre-amplifier pulses were also recorded and processed digitally to obtain electron and hole drift mobilities of 692 cm2 V−1 s−1 and 55 cm2 V−1 s−1, respectively, using a time-of-flight method. The measured transport properties indicated the hole lifetime to be greater than the electron lifetime by a factor of ∼1.5. Gamma-ray PHS were recorded using fabricated detectors that showed tailing of the 662 keV photopeak due to hole trapping effects. Depth dependent PHS were digitally generated from 2D biparametric plots to reveal the effects of hole trapping on the gamma PHS at different detector depths. Digital correction procedures were applied to generate well-resolved PHS with an energy resolution of ∼2% for 662 keV γ-rays. [ABSTRACT FROM AUTHOR]

Three 2-(thiopyran-4-ylidene)-1,3-benzodithiole (TP-BT) derivatives containing a phenyl (1), 2-pyridyl (2) or 4-pyridyl (3) group on the benzene moiety were synthesized to investigate the relationship between their molecular structure and semiconductor properties. Analysis of molecular orbital calculations revealed that the highest occupied molecular orbitals of 1–3 were distributed on the TP-BT moieties, and the lowest unoccupied molecular orbitals were located on the introduced aryl substituents, leading to donor–acceptor (D–A) type molecular structures. X-ray analysis of the two pyridyl-substituted compounds (2 and 3) revealed that 2-pyridyl-containing compound 2 formed a crystal structure with D–A segregated-type stacking through the formation of a hydrogen bond between the pyridyl nitrogen atom and the thiopyranyl hydrogen atom. 4-Pyridyl-containing compound 3 formed a D–A mixed-type layer structure in which molecules were aligned in an antiparallel fashion. The XRD analysis of 1–3 thin films revealed that d-spacings were close to their molecular lengths for all three compounds and the molecules formed edge-on arrangements on the substrates. Employing 1–3 as active layers in organic field-effect transistor (OFET) devices resulted in compound 1 exhibiting the highest hole mobility among these derivatives. The OFET device formed from 2 demonstrated less effective hole-transport properties; however, the device possessed a more stable small off current. The device formed from 3 was only active under photo-irradiation conditions, resulting in a unique photo-active OFET. [ABSTRACT FROM AUTHOR]

Acepleiadylene (APD), a nonbenzenoid isomer of pyrene, exhibits a unique charge‐separated character with a large molecular dipole and a small optical gap. However, APD has never been explored in optoelectronic materials to take advantage of these appealing properties. Here, we employ APD as a building block in organic semiconducting materials for the first time, and unravel the superiority of nonbenzenoid APD in electronic applications. We have synthesized an APD derivative (APD‐IID) with APD as the terminal donor moieties and isoindigo (IID) as the acceptor core. Theoretical and experimental investigations reveal that APD‐IID has an obvious charge‐separated structure and enhanced intermolecular interactions as compared with its pyrene‐based isomers. As a result, APD‐IID displays significantly higher hole mobilities than those of the pyrene‐based counterparts. These results imply the advantages of employing APD in semiconducting materials and great potential of nonbenzenoid polycyclic arenes for optoelectronic applications. [ABSTRACT FROM AUTHOR]

A series of donor‐π‐acceptor‐π‐donor (D‐π‐A‐π‐D) compounds based on naphthalendiimide (NDI) and perylenediimide (PDI) central cores combined with triphenylamine and phenylcarbazole donor groups have been synthesized, characterized and tested in top‐contact/bottom gate organic field‐effect transistors (OFETs). The results showed high electron mobilities, up to 0.3 cm2 V−1 s−1, in the case of NDI derivatives and moderate values of around 10−3 cm2 V−1 s−1 for PDI‐based semiconductors. Quantum chemical calculations were performed in order to support the experimental data. The results suggest that adequate molecular characteristics and larger crystalline domains in NDI vs. PDI semiconducting films may be the reasons behind the enhanced electrical properties of NDI derivatives. Furthermore, when the lateral donor substituents are triphenylamine groups, the mobilities were slightly higher in comparison to phenylcarbazole donor groups due to an improved electron‐donating character. Other characterization techniques, such as AFM, X‐ray diffraction or spectroelectrochemistry, among others, have been performed to analyze supramolecular order, charge carriers' nature and stability, parameters closely related to charge transport characteristics. [ABSTRACT FROM AUTHOR]

Polymer semiconductors are promising materials for stretchable, wearable, and implantable devices due to their intrinsic flexibility, facile functionalization, and solution processability at low temperatures. However, the crystalline domain of the conjugated structure for high charge carrier mobility in semiconducting polymers exhibits lower stretchability than that of the semi‐crystalline or amorphous domains. Herein, a set of thermoplastic soft semiconductors is synthesized with different ratios of diketopyrrolopyrrole–carbazole–diketopyrrolopyrrole (DPP‐Cz‐DPP)‐based hard segments and thiophene‐based aliphatic soft segments, having the similar structure of thermoplastic elastomers. The polymers exhibit decreased glassy temperatures with the increased content of the soft segments. The polymers show high crystallinity after copolymerization with a large‐sized DPP‐Cz‐DPP core and non‐conjugated segments due to an aggregation property of the conjugated core, still possessing a semi‐crystalline domain after annealing. The polymer films exhibit stretchability under strains of up to 60%. Organic field‐effect transistors fabricated using stretchable polymers show a mobility range of 0.125–0.005 cm2 V−1 s−1 with different proportions of the soft segment. The stretchability is improved significantly and the mobilities are decreased less when the content of the soft segment is increased. Therefore, this study presents a design principle for the development of a high‐performance stretchable semiconducting polymer. [ABSTRACT FROM AUTHOR]

The development of high-performance p-type oxides with high hole mobility and a wide bandgap is critical for the applications of metal oxide semiconductors in vertically integrated CMOS devices [Salahuddin et al., Nat. Electron. 1, 442 (2018)]. Sn2+-based oxides such as SnO and K2Sn2O3 have recently been proposed as high-mobility p-type oxides due to their relatively low effective hole masses, which result from delocalized Sn s-orbital character at the valence band edge. Here, we introduce a promising ternary Sn-O-X compound, Ta2SnO6, which exhibits strong valence band dispersion and a large bandgap. In order to evaluate the performance of this oxide as a p-type semiconductor, we perform first-principles calculations of the phonon-limited room-temperature carrier mobilities in SnO, SnO2, and Ta2SnO6. Electron relaxation time is evaluated, accounting for the scatterings from acoustic deformation potentials and polar optical phonons (POP), within the isotropic and dispersionless approximation. At room temperature, the electron/hole mobilities in a given material (SnO, SnO2, and Ta2SnO6) are found to be limited by POP scattering. SnO2 shows high room-temperature electron mobility of 192 cm2/(V s), while SnO and Ta2SnO6 exhibit impressive hole mobilities, with the upper limit at 60 and 33 cm2/(V s), respectively. We find that carrier effective mass largely accounts for the differences in mobility between these oxides with correspondingly different POP scattering rates. The theoretically predicted intrinsic mobilities of each material will provide the upper limit to the real mobilities for their device applications. Our findings also suggest a necessity of further investigation to identify even higher mobility p-type oxides with smaller hole effective masses. [ABSTRACT FROM AUTHOR]

The development of high-performance p-type oxides with high hole mobility and a wide bandgap is critical for the applications of metal oxide semiconductors in vertically integrated CMOS devices [Salahuddin et al., Nat. Electron. 1, 442 (2018)]. Sn2+-based oxides such as SnO and K2Sn2O3 have recently been proposed as high-mobility p-type oxides due to their relatively low effective hole masses, which result from delocalized Sn s-orbital character at the valence band edge. Here, we introduce a promising ternary Sn-O-X compound, Ta2SnO6, which exhibits strong valence band dispersion and a large bandgap. In order to evaluate the performance of this oxide as a p-type semiconductor, we perform first-principles calculations of the phonon-limited room-temperature carrier mobilities in SnO, SnO2, and Ta2SnO6. Electron relaxation time is evaluated, accounting for the scatterings from acoustic deformation potentials and polar optical phonons (POP), within the isotropic and dispersionless approximation. At room temperature, the electron/hole mobilities in a given material (SnO, SnO2, and Ta2SnO6) are found to be limited by POP scattering. SnO2 shows high room-temperature electron mobility of 192 cm2/(V s), while SnO and Ta2SnO6 exhibit impressive hole mobilities, with the upper limit at 60 and 33 cm2/(V s), respectively. We find that carrier effective mass largely accounts for the differences in mobility between these oxides with correspondingly different POP scattering rates. The theoretically predicted intrinsic mobilities of each material will provide the upper limit to the real mobilities for their device applications. Our findings also suggest a necessity of further investigation to identify even higher mobility p-type oxides with smaller hole effective masses. [ABSTRACT FROM AUTHOR]

The tin iodide-based hybrid perovskite (C6H5C2H4NH3)2SnI4 [(PEA)2SnI4] is promising as the semiconductor in field-effect transistors (FETs) because of its easy film processability and high carrier mobility. However, the stability of (PEA)2SnI4 FETs in air remains a significant issue. In this study, we show that the source of this degradation is oxygen. We observed that the structure of (PEA)2SnI4 degraded in the presence of oxygen, along with the formation of gaps between grains. With the aim of suppressing the oxygen-induced degradation, we optimized (PEA)2SnI4 spin-coating conditions to increase the grain size and simply encapsulated a (PEA)2SnI4 semiconductor with the fluorine-based polymer CYTOP. Adopting these methods led to the greatly improved stability of FET performance in air. We propose that oxygen had reduced penetration into (PEA)2SnI4 films with larger grains. The drain current of optimized FETs remained almost unchanged over 5 h of operation, which is in contrast to the control device that decayed within 1 h. [ABSTRACT FROM AUTHOR]

The recent progress in the design and synthesis of high-performance donor-acceptor conjugated polymeric semiconducting materials is reviewed from the perspective of multiscale structures. The multiscale of conjugated polymers is from the primary one-dimensional polymer molecular scale to the secondary polymer-chains interaction scale, and then to the tertiary polymer aggregate scale. This review focuses on the design and synthesis of polymer molecules, proposes new classification rules, and rationally summarizes the design strategies and modulation methods of polymers. We describe the recent progress from these three aspects: (1) the modification of π-conjugated backbone, (2) the evolution of the polymerization methods, and (3) the regulation of aggregate-state structure. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Diketopyrrolopyrrole (DPP) is one of the most promising building blocks for constructing polymer semiconductors with high charge‐carrier mobilities in organic field‐effect transistors (OFETs). In this study, a novel DPP‐based conjugated polymer, PDPPy‐BDD, was designed and synthesized. The ambipolar field‐effect transistor characteristics were realized with the average hole and electron mobilities of 3.5 × 10–3 and 3.07 × 10–2 cm2 V−1 s−1, respectively. Both the hole and electron mobilities could be successfully enhanced by using a tetramethylammonium iodide (NMe4I) additive. Such an enhancement was attributed to the formation of stronger interchain π–π stackings, the weakening of the face‐on packing orientation in the thin film state, and the higher channel conductivities in the OFETs. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Diketopyrrolopyrrole (DPP) is one of the most promising building blocks for constructing polymer semiconductors with high charge‐carrier mobilities in organic field‐effect transistors (OFETs). In this study, a novel DPP‐based conjugated polymer, PDPPy‐BDD, was designed and synthesized. The ambipolar field‐effect transistor characteristics were realized with the average hole and electron mobilities of 3.5 × 10–3 and 3.07 × 10–2 cm2 V−1 s−1, respectively. Both the hole and electron mobilities could be successfully enhanced by using a tetramethylammonium iodide (NMe4I) additive. Such an enhancement was attributed to the formation of stronger interchain π–π stackings, the weakening of the face‐on packing orientation in the thin film state, and the higher channel conductivities in the OFETs. [ABSTRACT FROM AUTHOR]

The electronic structure and thermoelectric properties of MoX2 (X = S, Se) Van der Waals heterojunctions are reported, with the intention of motivating the design of electronic devices using such materials. Calculations indicate the proposed heterojunctions are thermodynamically stable and present a band gap reduction from 1.8 eV to 0.8 eV. The latter effect is highly related to interactions between metallic d‐character orbitals and chalcogen p‐character orbitals. The theoretical approach allows to predict a transition from semiconducting to semi‐metallic behavior. The band alignment indicates a type‐I heterojunction and band offsets of 0.2 eV. Transport properties show clear n‐type nature and a high Seebeck coefficient at 300 K, along with conductivity values (σ/τ) in the order of 1020. Lastly, using the Landauer approach and ballistic transport, the proposed heterojunctions can be modeled as a channel material for a typical one‐gate transistor configuration predicting subthreshold values of ≈60 mV dec−1 and field–effect mobilities of ≈160 cm−2 V−1 s−1. [ABSTRACT FROM AUTHOR]

Herein, the magnetic field effect on the source–drain current of organic field‐effect transistors with semiconductor layers made of H‐bonded pigments is studied. In all devices, an external magnetic field reduces the source–drain current in the transistor. The magnetic field effect is independent of the direction of the applied magnetic field. The observed increase of the magnetoresistance seems to originate from the used semiconductor or the semiconductor–dielectric interface and is not influenced by the nature of the gate electrodes or the semiconductors' deposition procedure (e.g., grain size, layer thicknesses, etc.). As all prepared devices do have single charge carrier nature, the formation of bipolarons is suggested to be responsible for the observed magnetic field effect. The presented experiments demonstrate that hydrogen‐bonded semiconductors behave no different than their classical van der Waals‐bonded fully conjugated semiconductors' counterparts. [ABSTRACT FROM AUTHOR]

This review highlights selected examples, published in the last three to four years, of recent advance in the design, synthesis, properties, and device performance of quinoidal π-conjugated materials. A particular emphasis is placed on emerging materials, such as indophenine dyes that have the potential to enable high-performance devices. We specifically discuss the recent advances and design guidelines of π-conjugated quinoidal molecules from a chemical standpoint. To the best of the authors' knowledge, this review is the first compilation of literature on indophenine-based semiconducting materials covering their scope, limitations, and applications. In the first section, we briefly introduce some of the organic electronic devices that are the basic building blocks for certain applications involving organic semiconductors (OSCs). We introduce the definition of key performance parameters of three organic devices: organic field effect transistors (OFET), organic photovoltaics (OPV), and organic thermoelectric generators (TE). In section two, we review recent progress towards the synthesis of quinoidal semiconducting materials. Our focus will be on indophenine family that has never been reviewed. We discuss the relationship between structural properties and energy levels in this family of molecules. The last section reports the effect of structural modifications on the performance of devices: OFET, OPV and TE. In this review, we provide a general insight into the association between the molecular structure and electronic properties in quinoidal materials, encompassing both small molecules and polymers. We also believe that this review offers benefits to the organic electronics and photovoltaic communities, by shedding light on current trends in the synthesis and progression of promising novel building blocks. This can provide guidance for synthesizing new generations of quinoidal or diradical materials with tunable optoelectronic properties and more outstanding charge carrier mobility. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials are considered attractive semiconducting layers for emerging field-effect transistors owing to their unique electronic and optoelectronic properties. Polymers have been utilized in combination with 2D semiconductors as gate dielectric layers in field-effect transistors (FETs). Despite their distinctive advantages, the applicability of polymer gate dielectric materials for 2D semiconductor FETs has rarely been discussed in a comprehensive manner. Therefore, this paper reviews recent progress relating to 2D semiconductor FETs based on a wide range of polymeric gate dielectric materials, including (1) solution-based polymer dielectrics, (2) vacuum-deposited polymer dielectrics, (3) ferroelectric polymers, and (4) ion gels. Exploiting appropriate materials and corresponding processes, polymer gate dielectrics have enhanced the performance of 2D semiconductor FETs and enabled the development of versatile device structures in energy-efficient ways. Furthermore, FET-based functional electronic devices, such as flash memory devices, photodetectors, ferroelectric memory devices, and flexible electronics, are highlighted in this review. This paper also outlines challenges and opportunities in order to help develop high-performance FETs based on 2D semiconductors and polymer gate dielectrics and realize their practical applications. [ABSTRACT FROM AUTHOR]

Both UV-vis spectroscopy and GIWAXS data from pure polymer films and polymer:fullerene blends consistently indicated an increased face-to-face stacking cohesion in the presence of fluorine substituents. STXM and GIWAXS thus form a complementary set of techniques that can provide feedback on chemical and structural details of OSM, which can guide research on related thin film engineering and device properties. While many techniques available at SOLEIL have been applied to OSMs, the two techniques highly demanded by the users of the OSM community have been Scanning Transmission X-ray Microscopy (STXM) at the HERMES beamline and Grazing Incidence Wide-Angle X-ray Scattering (GIWAXS) at the SIRIUS beamline. STXM measurements of these two binary films performed at HERMES beamline revealed a significant difference in acceptor percentage composition. [Extracted from the article]

[Display omitted] • TIPS-pentacene thickness in polymer blends altered the gas sensing characteristics. • Adsorption analysis showed similar surface rates but different bulk responses. • 10 nm thick TIPS-pentacene exhibited a detection limit as low as 2.6 ppb. Organic field-effect transistor (OFET)-based gas sensors are highly valued for their sensitivity, cost-effectiveness, and operation at room temperature, making them ideal candidates for gas detection applications. For gas sensor performance, gas molecules must not only adsorb onto the organic semiconductor surface but also diffuse into the organic semiconductor-insulator interface that the conductive channel is formed. Therefore, the thickness of the active OSC layer is crucial in determining the efficiency of gas diffusion and the overall sensing response. This study analyzed the impact of semiconductor thin film thickness on gas sensing properties by adjusting the thickness of crystalline organic semiconductors. Using 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), known for its excellent response toward NO 2 , surface and interface characteristics were modulated through a blend approach. With all other conditions constant, the semiconductor film thickness significantly influenced NO 2 detection properties, with the highest sensitivity observed in films around 10 nm thick. A quantitative analysis using Langmuir isotherms demonstrated that reducing the OSC layer thickness from 20 nm to 10 nm could enhance the response speed by a factor of five. Furthermore, the limit of detection (LOD) for TIPS-pentacene films at this reduced thickness was found to be in the low parts per billion (ppb) range. [ABSTRACT FROM AUTHOR]

Field-effect transistors based on organic semiconducting materials (OFETs) have unique advantages of intrinsically mechanical flexibility, simple preparation process, low manufacturing cost, and large-area preparation. Through the innovation of new material design and device structures, the performance of device parameters such as mobility, on–off current ratio, and the threshold voltage (VTH) of OFETs continues to improve. However, the VTH shift of OFETs has always been an important problem restricting their practical applications. In this work, we observe that the VTH of polymer OFETs with the widely investigated device structure of a SiO2 bottom-gate dielectric is noticeably shifted by pre-applying a large gate voltage. Such a shift in VTH remains to a large extent, even after modifying the surface of the SiO2 dielectric using a hexamethyldisilazane (HMDS) self-assembled monolayer. This behavior of VTH can be ascribed to the charge trappings at the bulk of the SiO2. In addition, the generality of this observation is further proven by using two other conjugated polymers including p-type PDPP3T and n-type PTzNDI-2FT, and a similar trend is obtained. [ABSTRACT FROM AUTHOR]

Chemical versatility and compatibility with a vast array of processing techniques has led to the incorporation of organic semiconductors in various electronic and opto-electronic devices. One such device is the organic field-effect transistor (OFET). In this tutorial, we describe the structure, operation, and characterization of OFETs. Following a short historical perspective, we introduce the architectures possible for OFETs and then describe the device physics and the methods for extracting relevant device parameters. We then provide a brief overview of the myriad organic semiconductors and deposition methods that were adopted for OFETs in the past decades. Non-ideal device characteristics, including contact resistance, are then discussed along with their effects on electrical performance and on the accuracy of extracting device parameters. Finally, we highlight several measurements involving OFETs that allow access to fundamental properties of organic semiconductors and the mechanism of charge transport in these materials. [ABSTRACT FROM AUTHOR]

The article presents a study which explores about mechanically robust stretchable semiconductor metallization for skin-inspired organic transistors. It report a highly stretchable and robust metallization on an elastomeric semiconductor film based on metal-elastic semiconductor intermixing. It mentions the challenges in the development of stretchable metallization.

Van der Waals layered indium selenide (InSe) is an emerging star of the 2D semiconducting materials because of its excellent fundamental properties, such as ultrahigh carrier mobility, layer‐tunable bandgap, large elastic deformability, and rich polytypes. In addition, 2D layered indium selenide has demonstrated outstanding device performance including photodetector, field‐effect transistor, memory and synapse, mechanical and gas sensor, which has offered a new chance to next‐generation electrical and optoelectronic devices. This review presents a comprehensive summary of recent progress in 2D layered indium selenide. The novel fundamental properties and synthetic methods are summarized. Also, the indium selenide‐based state‐of‐the‐art electronic/optoelectronic devices, such as a functional field‐effect transistor, photodetector, and mechanical and gas sensors are systematically summarized. The techniques to enhance the performances of devices are also discussed. Finally, a brief discussion on the challenges and future opportunities as a guideline for this field is provided. [ABSTRACT FROM AUTHOR]

Large area and highly aligned polymer semiconductor sub-microwires were fabricated using the coaxial focused electrohydrodynamic jet printing technology. As indicated by the results, the sub-microwire arrays have smooth morphology, well reproducibility and controllable with a width of ~110 nm. Analysis shows that the molecular chains inside the sub-microwires mainly exhibited edge-on arrangement and the π-stacking direction (010) of the majority of crystals is parallel to the long axis of the sub-microwires. Sub-microwires based organic field effect transistors showed high mobility with an average of 1.9 cm2 V−1 s−1, approximately 5 times higher than that of thin film based organic field effect transistors. In addition, the number of sub-microwires can be conveniently controlled by the printing technique, which can subsequently concisely control the performance of organic field effect transistors. This work demonstrates that sub-microwires fabricated by the coaxial focused electrohydrodynamic jet printing technology create an alternative path for the applications of high-performance organic flexible device. Here, the authors fabricate large area and highly aligned polymer semiconductor sub-microwires arrays via coaxial focused electrohydrodynamic jet printing technology, achieving high on/off ratio and average mobility that is 5x higher than that of thin film based organic field effect transistors. [ABSTRACT FROM AUTHOR]

Electrolyte-gated organic field-effect transistors (EGOFETs) provide a versatile platform for ultrasensitive, fast, and reliable detection of biological molecules in liquid media using low-cost bioelectronic sensors. The key functional layers of the EGOFETs include the semiconductor and biorecognition layers based on conjugated organic molecules, which must meet high requirements for the operational stability in various electrolytes when detecting analytes. In this work, EGOFETs based on 2,6-dioctyltetrathienoacene as the semiconductor material were fabricated by the doctor blade method compatible with printing technologies. We also report on EGOFETs with the biorecognition layer based on a biotin-containing derivative of [1]benzothieno[3,2-b]benzothiophene, which was applied by the Langmuir—Schaeffer method. The possibility of stable operation of the fabricated EGOFETs in various electrolytes and their sensor responses to the electrolyte pH value and streptavidin are demonstrated. [ABSTRACT FROM AUTHOR]

This letter presents a thin-film transistor architecture, in which a “trench” is introduced between the source and drain electrode to enhance current flow. The top-gate top-contact oxide Trench thin-film transistor has a superior on-current per width of $27.7~\mu \text{A}/ \mu \text{m}$ at a drain voltage of 4.1 V. It also has a good subthreshold swing of 0.122 V/dec and turn-on voltage of −0.4 V. This study explores the operating mechanism of the high-current-driving Trench oxide thin-film transistor. [ABSTRACT FROM AUTHOR]

The reported Vertical Organic Field Effect Transistors (VOFETs) show either superior current and switching speeds or well-behaved transistor performance, especially saturation in the output characteristics. Through the study of the relationship between the device architecture or dimensions and the device performance, we find that achieving a saturation regime in the output characteristics requires that the device operates in the injection limited regime. In current structures, the existence of the injection limited regime depends on the source's injection barrier as well as on the buried semiconductor layer thickness. To overcome the injection limit imposed by the necessity of injection barrier, we suggest a new architecture to realize VOFETs. This architecture shows better gate control and is independent of the injection barrier at the source, thus allowing for several A cm-2 for a semiconductor having a mobility value of 0.1 cm² V-1 s-1. [ABSTRACT FROM AUTHOR]

In the article "High Mobility n-Type Imide-Based Semiconductor with Unusual Single-Crystal Packing Structure in Solution-Processed Thin Film," the authors discuss the importance of achieving favorable molecular packing in organic semiconductors for improved charge transport properties. They introduce a new cyano-substituted fluoranthene imide building block that successfully overcomes this challenge. The study provides valuable insights for researchers working on the development of organic field-effect transistors. [Extracted from the article]

High performance solution processable n‐type organic semiconductor is an essential element to realize low‐cost, all organic and flexible composite logic circuits. In the design of n‐type semiconducting materials, tuning the LUMO level of compounds is a key point. As a strong electron withdrawing unit, the introduction of chlorine atom into the chemical structure can increase the electron affinity of the material and reduce the LUMO energy level. Here, a series chlorine substituted N‐heteroacene analogues of 6,7,8,9‐tetrachloro‐4,11‐bis(4‐((2‐ethylhexyl)oxy)phenyl)‐[1,2,5]thiadiazolo[3,4‐b]phenazine (O4Cl), 6,7,8,9‐tetrachloro‐4,11‐bis(4‐((2‐ethylhexyl)thio)phenyl)‐[1,2,5]thiadiazolo[3,4‐b]phenazine (S4Cl), 1,2,3,4,8,9,10,11‐octachloro‐6,13‐bis(4‐((2‐ethylhexyl)oxy)phenyl)quinoxalino[2,3‐b]phenazine (8Cl) and 12Cl have been synthesized and characterized. Solution‐processed organic field‐effect transistors (OFETs) based on these four compounds exhibit good electron mobilities of 0.04 cm2 V−1 s−1, 0.01 cm2 V−1 s−1, 2×10−3 cm2 V−1 s−1 and 3×10−3 cm2 V−1 s−1, respectively, under ambient conditions. The results suggest that these chlorine substituted π‐conjugated N‐heteroacene analogues are promising n‐type semiconductors in OFET applications. [ABSTRACT FROM AUTHOR]

The charge transport of crystalline organic semiconductors is limited by dynamic disorder that tends to localize charges. It is the main hurdle to overcome in order to significantly increase charge carrier mobility. An innovative design that combines a chemical structure based on sulfur‐rich thienoacene with a solid‐state herringbone (HB) packing is proposed and the synthesis, physicochemical characterization, and charge transport properties of two new thienoacenes bearing a central tetrathienyl core fused with two external naphthyl rings: naphtho[2,3‐b]thieno‐[2′′′,3′′′:4′′,5′′]thieno[2″,3″:4′,5′]thieno[3′,2′‐b]naphtho[2,3‐b]thiophene (DN4T) and naphtho[1,2‐b]thieno‐[2′′′,3′′′:4′′,5′′]thieno[2′′,3′′:4′,5′]thieno[3′,2′‐b]naphtho[1,2‐b]thiophene are presented. Both compounds crystallize with a HB pattern structure and present transfer integrals ranging from 33 to 99 meV (for the former) within the HB plane of charge transport. Molecular dynamics simulations point toward an efficient resilience of the transfer integrals to the intermolecular sliding motion commonly responsible for strong variations of the electronic coupling in the crystal. Best device performances are reached with DN4T with hole mobility up to μ = 2.1 cm2 V−1s−1 in polycrystalline organic field effect transistors, showing the effectiveness of the electronic coupling enabled by the new aromatic core. These promising results pave the way to the design of high‐performing materials based on this new thienoacene, notably through the introduction of alkyl side‐chains. [ABSTRACT FROM AUTHOR]

Polyethylene is amongst the most used polymers, finding a plethora of applications in our lives owing to its high impact resistance, non-corrosive nature, light weight, cost effectiveness, and easy processing into various shapes from different sizes. Despite these outstanding features, the commodity polymer has been underexplored in the field of organic electronics. This work focuses on the development of new polymer blends based on a low molecular weight linear polyethylene (LPE) derivative with a high-performance diketopyrrolopyrrole-based semiconducting polymer. Physical blending of the polyethylene with semiconducting polymers was performed at ratios varying from 0 to 75 wt.%, and the resulting blends were carefully characterized to reveal their electronic and solid-state properties. The new polymer blends were also characterized to reveal the influence of polyethylene on the mechanical robustness and stretchability of the semiconducting polymer. Overall, the introduction of LPE was shown to have little to no effect on the solid-state properties of the materials, despite some influence on solid-state morphology through phase separation. Organic field-effect transistors prepared from the new blends showed good device characteristics, even at higher ratios of polyethylene, with an average mobility of 0.151 cm2 V−1 s−1 at a 25 wt.% blend ratio. The addition of polyethylene was shown to have a plasticizing effect on the semiconducting polymers, helping to reduce crack width upon strain and contributing to devices accommodating more strain without suffering from decreased performance. The new blends presented in this work provide a novel platform from which to access more mechanically robust organic electronics and show promising features for the utilization of polyethylene for the solution processing of advanced semiconducting materials toward novel soft electronics and sensors. [ABSTRACT FROM AUTHOR]

Three novel diketopyrrolopyrrole (DPP) based small molecules have been synthesized and characterized in terms of their chemical‐physical, electrochemical and electrical properties. All the molecules consist of a central DPP electron acceptor core symmetrically functionalized with donor bi‐thienyl moieties and flanked in the terminal positions by three different auxiliary electron‐acceptor groups. This kind of molecular structure, characterized by an alternation of electron acceptor and donor groups, was purposely designed to provide a significant absorption at the longer wavelengths of the visible spectrum: when analysed as thin films, in fact, the dyes absorb well over 800 nm and exhibit a narrow optical bandgap down to 1.28 eV. A detailed DFT analysis provides useful information on the electronic structure of the dyes and on the features of the main optical transitions. Organic field‐effect transistors (OFETs) have been fabricated by depositing the DPP dyes as active layers from solution: the different end‐functionalization of the dyes had an effect on the charge‐transport properties with two of the dyes acting as n‐type semiconductors (electron mobility up to 4.4 ⋅ 10−2 cm2/V ⋅ s) and the third one as a p‐type semiconductor (hole mobility up to 2.3 ⋅ 10−3 cm2/V ⋅ s). Interestingly, well‐balanced ambipolar transistors were achieved by blending the most performant n‐type and p‐type dyes with hole and electron mobility in the order of 10−3 cm2/V ⋅ s [ABSTRACT FROM AUTHOR]

Ferroelectric field‐effect transistors (FeFETs) with 2D semiconductors as channel materials have been fabricated to achieve miniaturized size, high storage, and low power consumption. The FeFETs are studied based on few‐layer MoS2 sheets on the non‐lead Bi0.85La0.15Fe0.92Mn0.08O3 (BLFMO) ferroelectric films with a large remnant polarization (Pr ≈36 μC cm−2). In FeFETs, the conductivity states of the 2D semiconductor can be tuned by the ferroelectric polarization. It is found that the MoS2‐based FeFETs display a large memory windows exceeding 25 V, a high on/off ratio (>105), remarkable program/erase ratio (≈104), competitive retention, endurance, and high‐speed performance. Moreover, the 2D based FeFETs exhibit switchable multi‐bit data storage by applying different amplitudes of negative gate voltage pulses to enhance the data storage density. On the basis of these characteristics, the 2D‐FeFETs are potentially able to meet the need for scalability, capacity, retention, and endurance of nonvolatile memory. [ABSTRACT FROM AUTHOR]