Search

In this contribution, we describe the various research domains in which RuII alkynyl derivatives are involved. Their peculiar molecular properties stem from a strong and intimate overlap between the metal centered d orbitals and the π system of the acetylide ligands, resulting in plethora of fascinating properties such as strong and tunable visible light absorption with a strong MLCT character essential for sensing, photovoltaics, light‐harvesting applications or non‐linear optical properties. Likewise, the d/π mixing results in tunable redox properties at low potential due to the raising of the HOMO level, and making those compounds particularly suited to achieve redox switching of various properties associated to the acetylide conjugated ligand, such as photochromism, luminescence or magnetism, for charge transport at the molecular level and in field effect transistor devices, or charge storage for memory devices. Altogether, we show in this review the potential of RuII acetylide compounds, insisting on the molecular design and suggesting further research developments for this class of organometallic dyes, including supramolecular chemistry. [ABSTRACT FROM AUTHOR]

This study developed a technology for a vertical field‐effect transistor (VFET) incorporating c‐axis aligned crystal oxide semiconductor on a Gen 3.5 glass substrate. VFETs, with a channel length of 0.5 μm, demonstrated stable characteristics with minimal variation, higher on‐state current compared with low‐temperature polysilicon FETs, and extremely low off‐state leakage current. A prototype 513‐ppi organic light‐emitting diode display that features a red, green, and blue stripe arrangement and includes an internal compensation circuit with a configuration of six transistors and two capacitors was fabricated by harnessing the advantageous features of VFETs. Such a display was previously unattainable with planar FETs. Thus, the developed VFET technology presents a viable pathway for achieving ultrahigh‐resolution panels on glass substrates. [ABSTRACT FROM AUTHOR]

Ultra‐wide bandgap semiconductors are gaining attention for their promising properties for UV optoelectronics and UV transparent electronics as well as high‐power applications. Among them, La‐doped SrSnO3 exhibits excellent properties both for deep‐UV transparent oxide semiconductors and deep‐UV transparent conducting oxide. Here, the demonstration of thin film transistors (TFTs) with full deep‐UV transparency is reported, including electrodes, gate oxide, and substrate. The lightly La‐doped SrSnO3 for the channel layer is grown on MgO (100) substrates with buffer layers by pulsed laser deposition. TFTs with a metal—insulator–semiconductor structure are fabricated using high‐k perovskite dielectric LaScO3 as the gate oxide. A degenerately La‐doped SrSnO3 is used as the gate, the source, and the drain electrodes to obtain good ohmic contact with the channel layer as well as UV transparency. The resultant device shows a field effect mobility value of ≈24 cm2 V−1 s−1 and an on/off ratio >106. The optical transmittance of the entire device (including the substrate) is found to be >75% at 300 nm in wavelength. Furthermore, the electrical characteristics of the device exhibit excellent stability under visible irradiation. This research highlights the potential of SrSnO3 in advancing the field of UV optoelectronics and UV transparent electronics. [ABSTRACT FROM AUTHOR]

The transport and noise properties of fabricated, high‐performance, gate‐all‐around silicon liquid‐gated nanowire field‐effect transistor devices are investigated in different concentrations of MgCl2 solutions. The critical concentration of MgCl2 solution for charge inversion at the solid‐liquid interface is verified using noise spectroscopy and confirmed using the capacitance‐voltage measurement technique. In this study, it is found that the Hooge parameter (αH) and the equivalent input noise (SU) can effectively reflect the ion behavior on the surface of the nanowire. Moreover, the noise curves for αH and SU indicate two turning points at concentrations of 10−4 and 10−1 m for a peak and a valley, respectively. The noise transformation is related to the behavior of ions near the solid‐liquid interface in solutions with different MgCl2 concentrations is revealed. The results show that noise spectroscopy is a powerful method for monitoring charge dynamic processes in the research field of biosensors. [ABSTRACT FROM AUTHOR]

The synthesis of bench‐stable conjugated π‐radicals is challenging owing to the lack of modular approaches, which greatly hampers their practical material screens and applications. Here, we demonstrate a spin‐distribution‐directed regioselective substitution strategy to introduce substituents into the specific positions of an olympicenyl radical in a stepwise manner, resulting in a series of highly stable radical species. The substituents can also adjust the crystal packing by means of steric and electronic factors, enabling the changing from a π‐dimer to a pseudo‐one‐dimensional chain. The first single crystal organic field‐effect transistor device based on a graphenic radical is fabricated in air, showing a hole mobility of up to 0.021 cm2 V−1 s−1 and excellent device stability. This approach may be generalized to diverse spin‐delocalized open‐shell organic radicals. [ABSTRACT FROM AUTHOR]

Silanization is one of the widely explored surface modification strategies for biofunctionalization of oxide interfaces. For biosensor applications, silanes with active terminal groups such as amine, thiol, carboxylic, and aldehyde groups are utilized in routine. In near‐field sensing schemes like biologically sensitive field‐effect transistors, it is crucial to generate a homogeneous layer of silane to confine the biointeractions in close vicinity of the sensor interface. The homogeneity of such biofunctional layer is determined by the surface activation and silanization protocol being applied. Herein, the impact of the surface activation process and silanization on electrical characteristics of field‐effect devices is studied comprehensively using an electrolyte‐oxide‐semiconductor (EOS) capacitor with a high‐quality gate oxide. The thermally grown silicon oxide (SiO2) interface is activated using acidic mixtures and plasma treatment, while the subsequent silanization steps are investigated comparatively using two different silanes (3‐aminopropyl triethoxysilane (APTES) and 3‐glycidyloxypropyl trimethoxysilane (GPTMS) in wet‐chemical and vapor‐phase processes. Furthermore, the optimized silanization process is utilized to immobilize an oligo strand at the EOS capacitor surface, followed by the hybridization of complementary oligo strands. The optimized protocol holds the potential for large‐scale production of functional oxide interfaces for various applications. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs), as a burgeoning class of crystalline porous materials, have made significant progress in their application to optoelectronic devices such as field‐effect transistors, memristors, and photodetectors. However, the insoluble features of microcrystalline two‐dimensional (2D) COF powders limit development of their thin film devices. Additionally, the exploration of spin transport properties in this category of π‐conjugated skeleton materials remains vacant thus far. Herein, an imine‐linked 2D Py‐Np COF nanocrystalline powder was synthesized by Schiff base condensation of 4,4′,4′′,4′′′‐(pyrene‐1,3,6,8‐tetrayl)tetraaniline and naphthalene‐2,6‐dicarbaldehyde. Then, we prepared a large‐scale free‐standing Py‐Np COF film via a top‐down strategy of chemically assisted acid exfoliation. Moreover, high‐quality COF films acted as active layers were transferred onto ferromagnetic La0.67Sr0.33MnO3 (LSMO) electrodes for the first attempt to fabricate organic spin valves (OSVs) based on 2D COF materials. This COF‐based OSV device with a configuration of LSMO/Py‐Np COF/Co/Au demonstrated a remarkable magnetoresistance (MR) value up to −26.5 % at 30 K. Meanwhile, the MR behavior of the COF‐based OSVs exhibited a highly temperature dependence and operational stability. This work highlights the enormous application prospects of 2D COFs in organic spintronics and provides a promising approach for developing electronic and spintronic devices based on acid‐exfoliated COF thin films. [ABSTRACT FROM AUTHOR]

The development of n-type organic semiconductors has evolved significantly slower in comparison to that of p-type organic semiconductors mainly due to the lack of electron-deficient building blocks with stability and processability. However, to realize a variety of organic optoelectronic devices, high-performance n-type polymer semiconductors are essential. Herein, conjugated microporous polymers (CMPs) comprising isoindigo acceptor units linked to benzene or pyrene donor units (BI and PI) showing n-type semiconducting behavior are reported. In addition, considering the challenges of deposition of a continuous and homogeneous thin film of CMPs for accurate Hall measurements, a plasma-assisted fabrication technique is developed to yield uniform thin films. The fully conjugated 2D networks in PI- and BI-CMP films display high electron mobility of 6.6 and 3.5 cm² V-1 s-1, respectively. The higher carrier concentration in PI results in high conductivity (5.3 mS cm-1. Both experimental and computational studies are adequately combined to investigate structure-property relations for this intriguing class of materials in the context of organic electronics. [ABSTRACT FROM AUTHOR]

A method is presented for scaling up the production of flakes of van der Waals materials via mechanical exfoliation. Using a roll‐to‐roll setup and an automatized, massive parallel exfoliation process, adhesive tapes with a high density of nanosheets of van der Waals materials are produced. The technique allows for obtaining a good trade‐off between large lateral size and excellent area scalability, while also maintaining low cost. The potential of the method is demonstrated through the successful fabrication of field effect transistors and flexible photodetectors in large batches. This low‐cost method to produce large area films out of mechanically exfoliated flakes is very general, and it can be applied to a variety of substrates and van der Waals materials and, moreover, it can be used to combine different van der Waals materials on top of each other. Therefore, it is believed that this production method opens an interesting avenue for fabrication of low‐cost devices while maintaining a good scalability and performance. [ABSTRACT FROM AUTHOR]

Electric‐field regulation of magnetic properties in perovskite manganites has attracted much attention for its potential in spintronics. For antiferromagnetic perovskite manganites, fewer studies are reported due to technological difficulties in probing their magnetic properties. Here, negative exchange bias (EB) is realized in epitaxial antiferromagnetic/ferromagnetic manganite bilayers with atomically flat interfaces. The low‐voltage pulse modulation of EB is demonstrated using the field‐effect device geometry with the ferroelectric copolymer, polyvinylidene fluoride with trifluoroethylene as a dielectric gating layer, antiferromagnetic La0.35Sr0.65MnO3 (AF‐LSMO) as pinning layer, and ferromagnetic La0.7Sr0.3MnO3 (FM‐LSMO) as conduction channel. Instead of using non‐volatile polarizations to control the EB, volatile polarizations in ferroelectric field effect transistors are suggested to be capable of modulating the EB. With high‐resolution electron microscopy and spectroscopy, the non‐volatile regulation of EB is attributed to the creation/annihilation of oxygen vacancies in the AF‐LSMO layer via low‐voltage pulses. This study reveals the effect of volatile electric polarizations in ferroelectric field effect devices and highlights the potential for low‐voltage pulse control of the physical properties in antiferromagnetic perovskite oxide insulators. [ABSTRACT FROM AUTHOR]

The 2D–0D hybrid photodetector, with its special structure, high sensitivity, and wavelength tunability, is reported as a promising candidate system for optoelectronic devices. As research on hybrid lead halide perovskite quantum dots (PQDs) has progressed, PQDs with high photoluminescence (PL) quantum yield and excellent absorption properties are increasingly applied in optoelectronic devices; however, PQD stability remains one of the biggest limitations on device performance. Here, it is reported that the properties and stability of the hybrid photodetectors are improved by surface passivation using the quaternary ammonium ligand (didodecyldimethylammonium bromide, DDAB). The average carrier lifetime of DDAB treated CsPbBr3 PQDs (DDAB‐capped PQDs) is longer than that of pristine CsPbBr3 PQDs by 6.68–14.88 ns. It is confirmed that the durability against water is reduced by only 25.8% at PL intensity and is preserved for more than 16 h. A 2D–0D hybrid photodetector is then fabricated by deposition of DDAB‐capped PQDs on the WSe2 field‐effect transistor device for a high‐performance photodetector. The WSe2/DDAB‐capped PQD hybrid photodetector exhibits an enhanced responsivity of 1.4 × 103 A W−1 and an improved detectivity of 3.1 × 1013 Jones under 40.0 µW cm−2 of a 405 nm laser. [ABSTRACT FROM AUTHOR]

Ferroelectric (FE) control of magnetism at nanoscale, for instance, FE control of the polarity of spin‐polarized current is crucial for technological advances in magnetoelectric and spintronic applications. However, this fascinating functionality has not been reported in nanoscale systems yet. Herein, a new class of FE/A‐type antiferromagnetic heterobilayer/FE van der Waals (vdW) multiferroic structures is found, in which the FE control of polarity of spin‐polarized current is found possible. Take Sc2CO2/CrSiTe3/CrGeTe3/Sc2CO2 heterostructure as a successful example. First‐principles calculations reveal that its polarity of half‐metallicity can be switched by flipping the FE polarization orientation. Meanwhile, device transport simulation shows that its up/down spin current transmission ratio is as large as 0.1 × 103 at P→↑↑\[\mathop {\rm{P}}\limits^ \to \uparrow \uparrow \] Sc2CO2 configuration and is only 2.6 × 10−3 at P→↓↓$\mathop {\rm{P}}\limits^ \to \downarrow \downarrow $ Sc2CO2 configuration in the vdW multiferroic heterostructures. Essentially, it stems from the reversible FE switch of the internal electric field across the CrSiTe3/CrGeTe3 heterobilayer and the FE control of the interfacial effect between Sc2CO2 and Cr(Si/Ge)Te3 layers. This work opens a direction for constructing low‐energy‐dissipation, non‐volatile, and high‐sensitive spintronic devices such as spin field‐effect transistors. [ABSTRACT FROM AUTHOR]

The debye length is a measure of the distance over which the electric field of a charged particle decays in an electrolyte solution. If the binding of the analyte to the surface of the transducer is too far away from the surface, the electric field to the analyte may decay over a distance greater than the debye length thereby reducing the sensitivity of the measurement. In this context, this study has developed a simple one‐step protein immobilization strategy to covalently attach proteins on the sensor surface. Our binding strategy, which uses hydrogen peroxide (H2O2) ensures that the analyte is attached as close as possible to the transducer surface. This study evaluates our findings by comparing our strategy with silane chemistry and elucidating the debye length effects with colorimetric assays and field effect devices. Additionally, as a case study, we also evaluated the performance of our methodology for the detection of glucose oxidation by a field effect device. Overall, the developed immobilization strategy avoids the effects of the debye length and improves the performance of the biosensor. [ABSTRACT FROM AUTHOR]

The article presents several news on Artificial Intelligence's use to identify potent antibiotics against the superbug Acinetobacter baumannii. Topics discussed include the potential of seaweed-derived material for thermochemical heat storage and a new light-absorbing material with applications in various technologies, from bioimaging to self-driving cars and solar cells.

Carbon nanotube (CNT)‐based transistor devices have been demonstrated and are seen as the next‐generation alternative to replace the current generation electronic devices based on silicon MOS technology. Their limitations, however, are related to their instability in ambient conditions and technical challenges in scaling up production of individual CNT devices. Herein, a simple technique to convert ambipolar (both n‐ and p‐carrier) individual CNT‐based transistors into unipolar (p‐type carrier) transistors that carry large currents ≈±7 mA before saturation is demonstrated. Such large current‐carrying capability from an individual or single‐bundle CNTs will be ideal for applications that require high currents such as output stages of radio frequency (RF) and audio amplifiers. This work highlights the ability to tune CNT‐based transistor devices to suit specific applications, which is essential for the development of next generation of nanoelectronics. [ABSTRACT FROM AUTHOR]

The development of conjugated polymers with high semiconducting performance and high reliability is of great significance for flexible electronics. Herein, we developed a new type of electron‐accepting building block; i.e. non‐symmetric half‐fused B←N coordinated diketopyrrolopyrrole (DPP) (HBNDPP), for amorphous conjugated polymers toward flexible electronics. The rigid B←N fusion part of HBNDPP endows the resulting polymers with decent electron transport, while its non‐symmetric structure causes the polymer to exhibit multiple conformation isomers with flat torsional potential energies. Thus, it gets packed in an amorphous manner in solid state, ensuring good resistance to bending strain. Combined with hardness and softness, the flexible organic field‐effect transistor devices exhibit n‐type charge properties with decent mobility, good bending resistance, and good ambient stability. The preliminary study makes this building block a potential candidate for future design of conjugated materials for flexible electronic devices. [ABSTRACT FROM AUTHOR]

A detailed review of sub‐5 nm 2D semiconductor monolayer (ML) field‐effect transistors (FETs) is presented. A brief introduction to the fundamentals of 2D materials and their properties is provided followed by a critical review to propose an appropriate channel material from the available 2D materials. Various device simulation techniques incorporating density functional theory (DFT) and nonequilibrium Green's function (NEGF) are discussed in order to comprehend the distinctive features of 2D materials and the ballistic performance of sub‐5 nm ML 2D FETs. Relevant, recent experimental progress is also discussed. The review suggests that sub‐5 nm monolayer FETs based on 2D semiconductors like black phosphorene, WSe2N4, silicene, tellurene, arsenene, WSe2, MoTe2, MoS2, InSe, α‐CS, MoSi2N4, WS2, Bi2O2Se, GeSe, SnSe2, SnS2, AsP, GeS, MoSi2N4, BiH, SnSe2 and MoTe2 show excellent device performance meeting the International Technology Roadmap for Semiconductor (ITRS) requirements (2013 Version) for both high‐performance (HP) and low‐power (LP) applications in terms of on‐state current, subthreshold swing (SS), delay time, and power delay product (PDP). [ABSTRACT FROM AUTHOR]

Reconfigurable field‐effect transistors, capable of being dynamically programmed during run‐time, overcome the static nature of conventional complementary metal‐oxide semiconductors by reducing the transistor count and the circuit path delay. Thereby, SiGe and Ge are predicted to boost drive currents, switching speed and to reduce power consumption. Nevertheless, Ge‐based reconfigurable field‐effect transistor prototypes have so far fallen short in reaching both the promised performance due to interface instability to their contacts and gate oxides, as well as in reaching the current–voltage symmetry necessary for circuit applicability. Here, a top‐down fabricated SiGe‐based reconfigurable transistor technology is reported that is comprised of a vertical Si‐Si0.67Ge0.33 heterostructure enabling the envisioned high and symmetric on‐currents of both n‐ and p‐type operation. Monolithic integration with single‐elementary crystalline Al contacts alleviates process variability compared to conventional Ni‐silicide/Ni‐germanide contacts and introduces an ultra‐thin Si interlayer providing stability and equal injection efficiency of holes and electrons. The implementation of a three top‐gate transistor in combination with a hysteresis‐free Si/SiO2/HfO2 gate stack enhances polarity control and leakage current suppression to limit static power dissipation. Importantly, the obtained Al‐Si‐SiGe multi‐heterojunction and advanced reconfigurable transistor design is the first Ge‐based technology showing the envisioned stability and performance enhancements. [ABSTRACT FROM AUTHOR]

An atomically precise ultrasmall Au(I)6 nanocluster where the six gold atoms are complexed by three sterically interlocking stabilizing ligands is reported, allowing a unique combination of efficient third harmonic generation (THG), intense photoluminescence quantum yield (35%), ultrafast quantum coherence, and electron accepting properties. The reaction of 6‐(dibutylamino)‐1,3,5‐triazine‐2,4‐dithiol (TRZ) with HAuCl4 leads to complexation by thiolation. However, intriguingly, another reduction step is needed to form the centrosymmetric Au(I)6TRZ3 clusters with the multifunctional properties. Here, ascorbic acid is employed as a mild reducing agent, in contrast to the classic reducing agents, like NaBH4 and NaBH3CN, which often produce mixtures of clusters or gold nanoparticles. Such Au(I)6 nanocluster films produce very strong THG response, never observed for nanoclusters. The clusters also produce brilliant single and multiphoton luminescence with exceptional stability. Density functional theory calculations and femtosecond transient absorption studies suggest ultrafast ligand‐to‐metal charge transfer, quantum coherence with long decoherence time 200–300 fs, and fast propagation of excitation from the core to the surrounding solvent. Finally, novel electron‐accepting ground state properties allow p‐doping of 2D field‐effect transistor devices. Summarizing, the potential of ultrasmall sterically interlocked Au(I) clusters, i.e., complexes allowed by the new sequential reduction protocol, towards multifunctional devices, fast photoswitches, and quantum colloidal devices is shown. [ABSTRACT FROM AUTHOR]

Metal oxide (MO) semiconductors are widely used in electronic devices due to their high optical transmittance and promising electrical performance. This work describes the advancement toward an eco‐friendly, streamlined method for preparing thin‐film transistors (TFTs) via a pure water‐solution blade‐coating process with focus on a low thermal budget. Low temperature and rapid annealing of triple‐coated indium oxide thin‐film transistors (3C‐TFTs) and indium oxide/zinc oxide/indium oxide thin‐film transistors (IZI‐TFTs) on a 300 nm SiO2 gate dielectric at 300 °C for only 60 s yields devices with an average field effect mobility of 10.7 and 13.8 cm2 V−1 s−1, respectively. The devices show an excellent on/off ratio (>106), and a threshold voltage close to 0 V when measured in air. Flexible MO‐TFTs on polyimide substrates with AlOx dielectrics fabricated by rapid annealing treatment can achieve a remarkable mobility of over 10 cm2 V−1 s−1 at low operating voltage. When using a longer post‐coating annealing period of 20 min, high‐performance 3C‐TFTs (over 18 cm2 V−1 s−1) and IZI‐TFTs (over 38 cm2 V−1 s−1) using MO semiconductor layers annealed at 300 °C are achieved. [ABSTRACT FROM AUTHOR]

Biomimetic smart nanochannels can regulate ion transport behavior responsive to the external stimuli, having huge potential in nanofluidic devices, sensors and energy conversion. Field‐effect nanofluidic diodes or transistors based on electric‐responsive nanochannels are emerging owing to their advantages such as non‐invasiveness, in situ, real time, and high efficiency. However, simultaneously realizing the voltage‐control of the ion conductance and ion current rectification (ICR) properties is still a big challenge. Here, a field‐effect iontronic device is developed based on ionomer/anodic aluminum oxide/conducting polymer sandwich‐structured nanochannel to realize the multi‐control of ion transport behaviors including ion conductance, ICR magnitude, and ICR direction by modulating the surface charge, wettability, and morphology of the nanochannel. The electroactive conducting polymer carries tunable surface charges responsive to the electric stimuli, leading to the regulation of ICR values. The complex three‐segment structures lead to the reverse of ICR direction by reconfiguring the charge distribution along with the whole channel. The switching wettability between hydrophilic and hydrophobic results in the regulation of ion conductance. Furthermore, the field‐effect iontronic device functions in a wide salinity range especially in hypersaline environment, due to the salinity‐adaptive properties of the membrane. A new route is provided for designing more functional field‐effect nanofluidic devices. [ABSTRACT FROM AUTHOR]

Disclosed herein is a RhCl3‐catalyzed peri‐selective C−H/C−H oxidative homo‐coupling of 1‐substituted naphthalenes, which provides a highly efficient and streamlined approach to chalcogen‐embedded anthanthrenes from readily available starting materials. Introducing O, S, and Se into the anthanthrene skeleton leads to gradually increased π–π stacking distances but significantly enhanced π–π overlaps with the growth of the hetero‐atom radius. Moderate π–π distance, overlap area, and intermolecular S−S interactions endow S‐embedded anthanthrene (PTT) with excellent 2D charge‐transport properties. Moreover, the transformation of p‐type to n‐type S‐embedded anthanthrenes is realized for the first time via the S‐atom oxidation from PTT to PTT‐O4. In organic field‐effect transistor devices, PTT derivatives exhibit hole transport with mobilities up to 1.1 cm2 V−1 s−1, while PTT‐O4 shows electron transport with a mobility of 0.022 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]

Molecules based on benzimidazolone‐dioxazine are known as blue/violet pigments and have been commercialized for decades. However, unfavorable solubility limits the application of these structures as building blocks of conjugated polymers despite their low band gaps. Herein, a series of donor–acceptor conjugated polymers containing soluble benzimidazolone‐dioxazine structures as the acceptors and oligothiophene as donors are synthesized and investigated. With increasing numbers of thiophene rings, the steric hindrance diminishes and high molecular weight polymers can be achieved, leading to an improved performance in organic field effect transistor devices. The hole mobility of polymers with three to six thiophene units is in the order of 10−1 cm2 V−1 s −1. Among all the polymers, polymer P3 with three thiophene units between benzimidazolone‐dioxazine structures shows the best hole mobility of 0.4 cm2 V−1 s −1. Grazing‐incidence wide‐angle X‐ray scattering results reveal that the high mobility of organic field‐effect transistors (OFETs) can be accredited by matched donor–acceptor packing in the solid thin films. [ABSTRACT FROM AUTHOR]

The review presents advances and main challenges of the affinity sensors based on field‐ effect transistors published during the last five years. The different nanomaterial‐based field‐effect transistors are classified according to the nature of the nanomaterials, beginning by silicon, the "gold‐standard" semiconductor, the gallium nitride semiconductor, the organic semiconductors, the silicon nanowires, the inorganic nanomaterials, the carbon nanotubes and the graphene. Due to its exceptional electrical properties, the main works are devoted to graphene. The obtained analytical performances for the detection of biomarkers, of DNA sequences and of miRNA are listed. The relation between the operational conditions ‐ nature of the nanomaterials, procedure of preparation, choice of the receptor molecule, method of immobilization – and the analytical performance are discussed. The perspective of industrialization of these affinity sensors based on field‐effect transistors is discussed. [ABSTRACT FROM AUTHOR]

Specific and label‐free detection of biological interactions is paramount to a plethora of technological applications ranging from home‐care diagnostics to smart agriculture and home security. The biologically‐modified field‐effect transistor (BioFET) is a promising sensing platform due to its inherent signal amplification, low power, and miniaturization. In the following a low‐cost meta‐nano‐channel BioFET (MNC BioFET) is reported that provides means to electrostatically control the size, shape, and location of the conducting channel such as to enhance the coupling between the locally‐occurring electrostatics of the biological interactions and the electrodynamics of the underlying conducting channel. Moreover, it provides means to electrostatically control the Debye screening length at the sensing area to increase the readout signal. The MNC BioFET is fabricated in a large‐scale silicon chip foundry that ensures robustness and stability, optimal noise levels and signal amplification, repeatability, and ultimate miniaturization with the potential for high‐end multiplexing in ultra‐small samples. In the current study, a specific and label‐free sensing of prostate specific antigen with the MNC BioFET is demonstrated, and show the dependency of the sensor signal on the channel configuration. Finally, an order of magnitude enhancement in readout signal is demonstrated by the electrostatic control of the screening length at the sensing area. [ABSTRACT FROM AUTHOR]

A dome‐shaped phase diagram of superconducting critical temperature upon doping is often considered as a hallmark of unconventional superconductors. This behavior, observed in SrTiO3‐based interfaces, whose electronic density is controlled by field‐effect, has not been explained unambiguously yet. Here, a generic scenario for the superconducting phase diagram of these oxide interfaces is elaborated based on transport experiments on a double‐gate LaAlO3/SrTiO3 field‐effect device and Schrödinger–Poisson numerical simulations of the quantum well. The optimal doping point of maximum Tc is ascribed to the transition between a single‐gap and a fragile two‐gap s±‐wave superconducting state involving bands of different orbital character. Close to this point, a bifurcation in the dependence of Tc on the carrier density, which can be controlled by the details of the doping execution, is observed experimentally and reproduced by numerical simulations. Where doping with a back‐gate triggers the filling of a new dxy${d_{{\rm{xy}}}}$ subband and initiates the overdoped regime, doping with a top‐gate delays the filling of the subband and maintains the 2D electron gaz in the single‐gap state of higher Tc. Such a bifurcation, whose branches can be followed reversibly, provides a generic explanation for the dome‐shaped superconducting phase diagram that could be extended to other multiband superconducting materials. [ABSTRACT FROM AUTHOR]

Flexible artificial synapses, which use flexible electronic devices to simulate biological synapses, are the cornerstone of brain‐like computers and artificial intelligence systems. Devices based on field‐effect transistors (FETs) are suitable for emulating synaptic functions because of their diverse material selection, controllable parameters, and clear working mechanism. In addition, owing to their material fabrication and structural design, FETs can realize the special operation mechanisms of devices for constructing flexible artificial synapses with multiple functions. Herein, the essential principles of carrier transport in flexible artificial synapses based on FETs are focused. First, the selection of materials, carrier transfer mechanisms, and synaptic functions of flexible synaptic devices based on various transistors are summarized in detail. Subsequently, the applications of flexible synaptic devices in conformal artificial tactile and visual systems are introduced. Finally, future challenges and opportunities of flexible synaptic devices toward artificial neuromorphic electronics are discussed. [ABSTRACT FROM AUTHOR]

With the growing demands in flexible electronics, the development of plastic and organic materials has gained increased interest. In this focus review, the design concepts and recent advances of organic liquid crystalline materials in optoelectronic devices were introduced. Thermotropic liquid crystalline materials are categorized into three types: calamitic, discotic, and cholesteric types according to the structures of rod‐like, disk‐like, and chiral rod‐like molecules, respectively. Numerous liquid crystalline materials have been successfully incorporated in organic electronic devices. Notably, smectic liquid crystals hold great promise as semiconducting channel, floating gate electret, and charge transporting interlayer in field‐effect transistors, nonvolatile memory, and photovoltaics, respectively. This review sheds light on the great potential and importance of the organic liquid crystalline material for optoelectronic device applications. [ABSTRACT FROM AUTHOR]

Artificial photosynthesis for hydrogen production is an important element in the search for green energy sources. The incorporation of photoactive units into mechanically stable 2D materials paves the way toward the realization of ultrathin membranes as mimics for leaves. Here we present and compare two concepts to introduce a photoactive RuII polypyridine complex into ≈1 nm thick carbon nanomembranes (CNMs) generated by low‐energy electron irradiation induced cross‐linking of aromatic self‐assembled monolayers. The photoactive units are either directly incorporated into the CNM scaffold or covalently grafted to its surface. We characterize RuII CNMs using X‐ray photoelectron, surface‐enhanced Raman, photothermal deflection spectroscopy, atomic force, scanning electron microscopy, and study their photoactivity in graphene field‐effect devices. Therewith, we explore the applicability of low‐energy electron irradiation of metal complexes for photosensitizer nanosheet formation. [ABSTRACT FROM AUTHOR]

The development of techniques for tuning/controlling the properties of electronic devices such as field‐effect transistors (FETs) is important for the optimization of device performance or the realization of custom‐designed device functions. Here, a simple method for tuning the performance of 2D perovskite ((PEA)2SnI4) FETs by transferring organic semiconductor PDVT‐10 films onto (PEA)2SnI4 films to form van der Waals heterojunctions (vdWHs) is presented. By varying the electrical properties of PDVT‐10 with doping technique, the performance of (PEA)2SnI4 FETs can be effectively tuned in terms of on‐state current, threshold voltage, and mobility, with mobility increased from 0.10 cm2 V−1 s−1 for pristine (PEA)2SnI4 FETs to 0.46 cm2 V−1 s−1 for the vdWH‐based FETs. This phenomenon can be attributed to the holes transfer occurring at heterojunction interface. More interestingly, the performance of the (PEA)2SnI4 FETs can be almost fully recovered once the PDVT‐10 films are removed, indicating the reversibility of the method. Such method of tuning semiconductor device performance by forming vdWHs can be also extended to other semiconductors and devices. [ABSTRACT FROM AUTHOR]

2D organic semiconductor single crystals comprising one or a few molecular layers of macroscopic lateral sizes are ideal materials for ultrathin, flexible, and transparent field‐effect devices—a platform for transistors and sensors. In recent years, these 2D materials have demonstrated high performance not inferior to their 3D counterparts. However, light emissive properties of 2D organic semiconductor single crystals have not yet been reported, and a combination of high charge‐carrier mobility and bright luminescence in one material is still a challenge for 2D organic optoelectronics. Emissive high‐mobility 2D organic semiconductor based on a [1]benzothieno[3,2‐b]benzothiophene (BTBT)‐derivative, 2,7‐bis(4‐decylphenyl)[1]benzothieno[3,2‐b][1]benzothiophene (DPBTBT), is presented here. DPBTBT molecules self‐organize in large‐area ultrathin single‐crystalline films consisting of one or a few molecular layers. These 2D single crystals perfectly suit as an active layer of organic field‐effect transistors in full accordance with Shockley's model and uniquely combine the high charge‐carrier mobility reaching 7.5 cm2 V–1 s–1 with prominent light emissive properties, which allow a demonstration of the first 2D organic light‐emitting transistor. The high charge‐carrier mobility and thermal stability of the crystalline phases, pronounced luminescence, and good shelf‐life stability suggest that emissive BTBT‐type molecules are a promising avenue for 2D organic optoelectronics. [ABSTRACT FROM AUTHOR]

High performance organic field effect transistor devices based on intrinsically scalable materials are of great significance in wearable electronics. In this work, an exclusive approach is reported to rationale the carrier mobility and stretchability of the conjugate polymers (CPs) by modifying the symmetry of the side chains species. Semiconductor CPs with symmetrical alkyl side chains (P(C‐C)), symmetrical siloxane side chains (P(Si‐Si)), and asymmetrical silicon‐carbon side chains (P(C‐Si)) are synthesized to investigate the influence of these side chains on the carrier mobility and mechanical behavior. The result shows that silicon‐carbon asymmetric side chains can modulate the aggregation degree of polymer chains with a coherence length of 134 Å and maintain the mobility at 0.90 cm2 V−1 s−1. P(C‐Si) exhibits superior tensile properties that even elongation up to 100% the value of mobility retains a majority properties. The main reason is that the lowest coherence length of P(C‐Si) polymer leads to an increased proportion of amorphous zones in its polymer film, which efficiently dissipates mechanical stresses. This study provides an efficient strategy for the design and synthesis of the CPs with high carrier transport properties‐mechanical stability. [ABSTRACT FROM AUTHOR]

As human activities expand into naturally or man‐made radiation‐prone environment, the need for radiation‐hardened (Rad‐Hard) electronic hardware surges. The state‐of‐the‐art silicon‐based and 2D materials‐based Rad‐Hard transistors can withstand up to 1 Mrad (Si) of total ionization dose (TID), while higher TID tolerance is being heatedly sought after. Here, few‐layer MoS2 Rad‐Hard field‐effect transistors (FETs) with polymer solid electrolyte (PSE) gate dielectrics are presented. The MoS2 PSE‐FETs exhibit a TID tolerance of up to 3.75 Mrad (Si) at a dose rate of 523 rad (Si) s−1 and can be repaired with a moderate thermal annealing at 100 °C for 5 min. Combining the excellent intrinsic radiation tolerance and the reparability, the MoS2 PSE‐FETs reach a TID tolerance of up to 10 Mrad (Si). Complementary metal–oxide–semiconductor‐like MoS2 PSE‐inverters are built and show high radiation tolerance as well. Furthermore, the feasibility of wafer‐scale Rad‐Hard PSE‐inverter array is demonstrated using chemical vapor deposition grown monolayer MoS2. These studies uncover the potential of 2D materials‐based PSE devices in future Rad‐Hard integrated circuits. [ABSTRACT FROM AUTHOR]

Here, we account the synthesis and characterization of a series of symmetrical fused heterocyclic aromatic hydrocarbons (HAHs) with an indolo[1,2‐c]quinazoline (IQ) as the core moiety. All the new HAHs IQ series were systematically investigated by using various spectroscopic methods. Furthermore, their photo‐physical properties were supported by density functional theory (DFT) and time‐dependent density functional theory (TDDFT) studies to support the experimental findings. The tetramethyl‐substituted indolo[1,2‐c]quinazoline (TMIQ) compound is shown to exhibit the shifted type of π–π stacking interactions, which render this series as a new semiconducting material. Single‐crystal‐based field‐effect transistor devices of TMIQ exhibited efficient charge transport behavior, giving a p‐channel field‐effect mobility of 0.25 cm2 V−1 s−1 with an on/off ratio of 5 × 105. [ABSTRACT FROM AUTHOR]

Nanoporous graphene (NPG) can exhibit a uniform electronic band gap and rationally‐engineered emergent electronic properties, promising for electronic devices such as field‐effect transistors (FETs), when synthesized with atomic precision. Bottom‐up, on‐surface synthetic approaches developed for graphene nanoribbons (GNRs) now provide the necessary atomic precision in NPG formation to access these desirable properties. However, the potential of bottom‐up synthesized NPG for electronic devices has remained largely unexplored to date. Here, FETs based on bottom‐up synthesized chevron‐type NPG (C‐NPG), consisting of ordered arrays of nanopores defined by laterally connected chevron GNRs, are demonstrated. C‐NPG FETs show excellent switching performance with on–off ratios exceeding 104, which are tightly linked to the structural quality of C‐NPG. The devices operate as p‐type transistors in the air, while n‐type transport is observed when measured under vacuum, which is associated with reversible adsorption of gases or moisture. Theoretical analysis of charge transport in C‐NPG is also performed through electronic structure and transport calculations, which reveal strong conductance anisotropy effects in C‐NPG. The present study provides important insights into the design of high‐performance graphene‐based electronic devices where ballistic conductance and conduction anisotropy are achieved, which could be used in logic applications, and ultra‐sensitive sensors for chemical or biological detection. [ABSTRACT FROM AUTHOR]

The development of multi‐valued logic devices, which involve switching between more than two states, is one of the promising approaches for overcoming the issues caused by the further scaling down of the current complementary metal‐oxide semiconductor devices. This paper presents ternary devices based on MoS2/h‐BN/graphene heterostructures, in which an active channel of MoS2 is partially aligned with a floating gate of graphene, unlike in the case of typical flash memory devices; thus, they can be regarded as a circuit consisting of a memory device and field‐effect transistor internally connected in parallel. The transfer curves of these devices exhibit two different threshold voltages (Vth) with ternary states ("0," "1," and "2"). Furthermore, the intermediate state can be controlled by oxygen plasma treatment, resulting in a ratio >102 for "1"/"0" states and "2"/"1" states. Thus, these devices can be used to implement a resistive‐load standard ternary inverter, whose output voltage is close to 1, 0.5, and 0 V under the supply voltage of 1 V. In addition, ternary NMIN and NMAX circuits with resistive loads are demonstrated by connecting two ternary inverters in series and parallel, respectively. [ABSTRACT FROM AUTHOR]

The deposition of dielectric materials on graphene is one of the bottlenecks for unlocking the potential of graphene in electronic applications. The plasma enhanced atomic layer deposition of 10 nm thin high quality aluminum oxide (Al2O3) on graphene is demonstrated using a monolayer of hexagonal boron nitride (hBN) as protection layer. Raman spectroscopy is performed to analyze possible structural changes of the graphene lattice caused by the plasma deposition. The results show that a monolayer of hBN in combination with an optimized deposition process can effectively protect graphene from damage, while significant damage is observed without an hBN layer. Electrical characterization of double gated graphene field effect devices confirms that the graphene does not degrade during the plasma deposition of Al2O3. The leakage current densities are consistently below 1 pA µm−2 for electric fields across the insulators of up to 8 MV cm−1, with irreversible breakdown happening above. Such breakdown electric fields are typical for Al2O3 and can be seen as an indicator for high quality dielectric films. [ABSTRACT FROM AUTHOR]

Deliberately tuning the photodetecting performances of polymer/graphene (G) hybrid films through a simple approach and understanding its underlying mechanisms are of significance for developing related devices. Herein, photodetecting features of polymer/G films are successfully tuned from broadband to IR/UV sensitive through a simple thermal treatment, providing optional working modes for varied demands. The morphologies and electronic/photodetecting properties of polymer/G hybrids are characterized in detail through atomic force microscopy, scanning electron microscopy, grazing‐incident wide angle X‐ray scattering, field effect transistor devices, and density functional theory calculations. The results suggest that the synergetic effect between Fermi level of G and morphologies of polymer film is responsible for the altered sensitivities to different radiations. The former factor shifts the energy barrier of charge carrier transferring for photocurrent generation, while the latter modifies the absorption capabilities of polymer films to the specific lights. Thus, in this work, besides proposing an in‐principle multimode photodetecting device for different applications, the intrinsic mechanisms behind the performance modifications and the robust capabilities of simple thermal treatments on tuning activities of polymer/G devices are revealed as well, which provide valuable supports for developing efficient photosensing devices in a facile and rational approach. [ABSTRACT FROM AUTHOR]

Charge‐based field‐effect transistors (FETs) greatly suffer from unavoidable carrier scattering and heat dissipation. Analogous to valley degree of freedom in semiconductors, chiral anomaly current in Weyl/Dirac semimetals is theoretically predicted to be nearly nondissipative over long distances, but still lacks experimental ways to efficiently control its transport. Here, field‐effect chirality devices are demonstrated with Dirac semimetal PtSe2, in which its Fermi level is close to the Dirac point in the conduction band owing to intrinsic defects. The chiral anomaly is further corroborated by the planar Hall effect and nonlocal valley transport measurement, which can also be effectively modulated by external fields, showing robust nonlocal valley transport with micrometer diffusion length. Similar to charge‐based FETs, the chiral conductivity in PtSe2 devices can be modulated by electrostatic gating with an ON/OFF ratio of more than 103. Basic logic functions in the devices are also demonstrated with electric and magnetic fields as input signals. [ABSTRACT FROM AUTHOR]

Semiconductor nanostructures have raised much hope for the implementation of high‐performance thermoelectric generators. Indeed, they are expected to make available reduced thermal conductivity without a heavy trade‐off on electrical conductivity, a key requirement to optimize the thermoelectric figure of merit. Here, a novel nanodevice architecture is presented in which ionic liquids are employed as thermally‐insulating gate dielectrics. These devices allow the field‐effect control of electrical transport in suspended semiconducting nanowires in which thermal conductivity can be simultaneously measured using an all‐electrical setup. The resulting experimental data on electrical and thermal transport properties taken on individual nanodevices can be combined to extract ZT, guide device optimization and dynamical tuning of the thermoelectric properties. [ABSTRACT FROM AUTHOR]

This paper describes an efficient simulation technique for field‐effect transistor devices exhibiting significant frequency dispersive behavior. The device model is formulated such that a single energy function completely describes the channel displacement current, thus imposing charge and energy conservations principles from the outset. It is shown that adherence to energy conservation necessarily implies a reciprocal intrinsic displacement network, which is typically too rigid to follow measured device data. This problem is overcome by considering a frequency dispersive time‐delay parameter, which has the effect of allowing nonreciprocal susceptance behavior to be captured by the overall device model. This dispersive time‐delay parameter is included within the nonlinear device simulation via an efficient discrete‐time convolution. [ABSTRACT FROM AUTHOR]

A new functionalization method to modify capacitive electrolyte–insulator–semiconductor (EIS) structures with nanofilms is presented. Layers of polyallylamine hydrochloride (PAH) and graphene oxide (GO) with the compound polyaniline:poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) (PANI:PAAMPSA) are deposited onto a p‐Si/SiO2 chip using the layer‐by‐layer technique (LbL). Two different enzymes (urease and penicillinase) are separately immobilized on top of a five‐bilayer stack of the PAH:GO/PANI:PAAMPSA‐modified EIS chip, forming a biosensor for detection of urea and penicillin, respectively. Electrochemical characterization is performed by constant capacitance (ConCap) measurements, and the film morphology is characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). An increase in the average sensitivity of the modified biosensors (EIS–nanofilm–enzyme) of around 15% is found in relation to sensors, only carrying the enzyme but without the nanofilm (EIS–enzyme). In this sense, the nanofilm acts as a stable bioreceptor onto the EIS chip improving the output signal in terms of sensitivity and stability. [ABSTRACT FROM AUTHOR]

Summary: This paper presents a double‐gate line‐tunneling field‐effect transistor (DGLTFET) device optimized for superior analog performance. DGLTFET has thrice the on currents Ion, at least one order lower off currents I o f f, twice the transconductance gm, at least two orders higher output resistance ro, and at least two orders higher overall intrinsic gain gmro than the equivalent metal‐oxide‐semiconductor field‐effect transistor (MOSFET) having the same width at the same technology node. The proposed device, being a double‐gate (DG) structure, exhibits extremely high vertical fields which ensures that line‐tunneling dominates over the point‐tunneling by several orders. This eliminates the notorious "hump" or the "kink" effects observed in conventional LTFET characteristics, which are detrimental for analog applications. In this work, we have optimized the DGLTFET device by changing critical parameters like the epi‐layer thickness and its doping concentration, which have serious influence on the line‐tunneling behavior. Optimization of the critical parameters for enhanced line‐tunneling leads to improved analog performance parameters like gm and ro, and finally, superior analog circuits. The performance of the DGLTFET was benchmarked with the equivalent MOSFET in fundamental analog VLSI circuits, namely, CS amplifier (both resistive and cascode loads), current mirror (both single‐stage and cascode configurations), and a two‐stage op‐amp. This paper shows that the DGLTFET CS amplifier has a gain‐BW product or unity‐gain BW fT of 15 GHz, while that of MOSFET CS amplifier with the same bias current is 10 GHz. The DGLTFET current mirror has at least three orders of magnitude higher ro than the corresponding MOSFET current mirror. Similarly, the common‐mode rejection ratio (CMRR) of the DGLTFET op‐amp is 57 dB compared to the CMRR of 33.5 dB of the equivalent design in standard 45‐nm complementary metal‐oxide semiconductor (CMOS) technology. The 45‐nm library is the lowest industry‐standard technology node currently available free for academic licenses in the public domain; hence, the benchmarking for validation was carried out at 45 nm. However, the claims/investigations made in this work are also valid for lower technologies, and related results are excluded in this report keeping the manuscript length in mind. [ABSTRACT FROM AUTHOR]

A set of ethynylene‐bridged anthracene oligomers from monomer to tetramer is synthesized and characterized. The red‐shifts in the UV–vis absorption and fluorescence spectra indicate the π‐extension with elongation of the linear chain. Cyclic voltammetric measurements suggest that their highest occupied molecular orbitals are located lower than –5.0 eV, indicating high air stability. Single‐crystal X‐ray analysis of a trimer needle crystal indicates that anthracene units display a twisted arrangement, adopting a face‐to‐face packing structure. The dip‐coating method with a very slow pulling rate provides crystalline films of dimer and trimer. The top‐contact bottom‐gate organic field‐effect transistor devices reveal that trimer shows better charge transport property (8.0 × 10–3 cm2 V–1 s–1) than dimer (8.9 × 10–4 cm2 V–1 s–1). Furthermore, the single‐crystal field‐effect transistor of trimer shows mobility up to 0.14 cm2 V–1 s–1, which is higher than that of tetramer (3.3 × 10–2 cm2 V–1 s–1). This is likely due to the larger amount of defects in tetramer crystals that are caused by the free rotation of ethynylene units, while the trimer achieves a good balance between the effective π‐conjugation and defectless crystal formation. [ABSTRACT FROM AUTHOR]

Development of high‐performance p‐channel thin‐film transistors (TFTs) can be an essential building block for next‐generation display technologies which require a great power efficiency. While an n‐channel InGaZnO TFT has been practically demonstrated, the counterparts are still challenging because of their ionic bonding nature. Here we report high‐performance p‐channel hexagonal tellurium (Te) TFT which exhibits outstanding device performances with a field‐effect mobility of 21.2 cm2/Vs, a current modulation ratio of 2.3 × 105, a subthreshold swing of 0.2 V/dec, and a threshold voltage of ‐0.3 V. This study shows a strong potential of p‐channel Te TFT for next‐generation display applications. [ABSTRACT FROM AUTHOR]

Oxide thin film transistors (TFTs) represented by n‐type amorphous InGaZnOx (a‐IGZO) have revolutionized the display industry. However, the lack of p‐type counterparts hinders the development of high‐resolution displays with lower energy consumption. In this paper, we review the recent trend in the material design and devices of p‐type oxide semiconductors. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) has been extensively investigated for use in large‐area electronics; in particular, the solution‐processing routes have shown increasing promise towards low‐cost fabrication. However, top‐down fabrication approaches with nanoscale resolution, towards aggressively scaled device platforms, are still underexplored. This study reports a novel approach of direct‐write electron‐beam lithography (DW‐EBL) of solution precursors as negative tone resists, followed by optimal precursor processing to fabricate micron/nano‐field‐effect transistors (FETs). It is demonstrated that the mobility and current density of ZnO FETs can be increased by two orders of magnitude as the precursor pattern width is decreased from 50 µm to 100 nm. These nano‐FET devices exhibit field‐effect mobility exceeding ≈30 cm2 V−1 s−1 and on‐state current densities reaching 10 A m−1, the highest reported so far for direct‐write precursor‐patterned nanoscale ZnO FETs. Using atomic force microscopy and parametric modeling, the origin of such device performance improvement is investigated. The findings emphasize the influence of pre‐decomposition nanoscale precursor patterning on the grain morphology evolution in ZnO and, consequently, open up large‐scale integration, and miniaturization opportunities for solution‐processed, high‐performance nanoscale oxide FETs. [ABSTRACT FROM AUTHOR]

Driven by the interest in fundamental physics and potential applications in novel electronic devices, intense effort is devoted to integration of oxide‐based 2D electron gases (2DEGs) with other functional materials. As a classic model system, LaAlO3/SrTiO3 (LAO/STO) has gained significant attentions. However, due to limitations in synthesis and high demands on the involved thin films, the formation of conductive interfaces between artificially grown STO and LAO thin films is an extreme challenge; oftentimes these interfaces remain insulating or show poor transport properties, which inhibits the development of all‐thin‐film devices. Here, by adopting high temperature growth to achieve step‐flow growth mode and fine‐tuning the laser fluence during pulsed laser deposition, high quality homoepitaxial STO thin films with sufficiently low point‐defect concentration and controllable surface termination are obtained. Fully metallic 2DEGs are then realized at interfaces between STO thin films and both crystalline and amorphous LAO overlayers. The observed slightly reduced mobility in the bilayer LAO/STO/STO structures as compared with single‐layer LAO/STO structures is related to residual defect formation during STO synthesis, yielding a disordered metallic oxide system. The results give prospect of multilayer interfaces potentially accessible in superlattice structures and provide a reliable starting point for back‐gated all‐thin‐film field‐effect devices. [ABSTRACT FROM AUTHOR]

Organolead halide hybrid perovskite solar cells (PSCs) have become a shining star in the renewable devices field due to the sharp growth of power conversion efficiency; however, interfacial recombination and carrier‐extraction losses at heterointerfaces between the perovskite active layer and the carrier transport layers remain the two main obstacles to further improve the power conversion efficiency. Here, novel field‐effect passivation has been successfully induced to effectively suppress the interfacial recombination and improve interfacial charge transfer by incorporating interfacial polarization via inserting a high work function interlayer between perovskite and holes transport layer. The charge dynamics within the device and the mechanism of the field‐effect passivation are elucidated in detail. The unique interfacial dipoles reinforce the built‐in field and prevent the photogenerated charges from recombining, resulting in power conversion efficiency up to 21.7% with negligible hysteresis. Furthermore, the hydrophobic interlayer also suppresses the perovskite decomposition by preventing the moisture penetration, thereby improving the humidity stability of the PSCs (>91% of the initial power conversion efficiency (PCE) after 30 d in 65 ± 5% humidity). Finally, several promising research perspectives based on field‐effect passivation are also suggested for further conversion efficiency improvements and photovoltaic applications. [ABSTRACT FROM AUTHOR]

Germanane (GeH), a germanium analogue of graphane, has recently attracted considerable interest because its remarkable combination of properties makes it an extremely suitable candidate to be used as 2D material for field effect devices, photovoltaics, and photocatalysis. Up to now, the synthesis of GeH has been conducted by substituting Ca by H in a β‐CaGe2 layered Zintl phase through topochemical deintercalation in aqueous HCl. This reaction is generally slow and takes place over 6 to 14 days. The new and facile protocol presented here allows to synthesize GeH at room temperature in a significantly shorter time (a few minutes), which renders this method highly attractive for technological applications. The GeH produced with this method is highly pure and has a band gap (Eg) close to 1.4 eV, a lower value than that reported for germanane synthesized using HCl, which is promising for incorporation of GeH in solar cells. [ABSTRACT FROM AUTHOR]