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The evolutionary success in information technology has been sustained by the rapid growth of sensor technology. Recently, advances in sensor technology have promoted the ambitious requirement to build intelligent systems that can be controlled by external stimuli along with independent operation, adaptivity, and low energy expenditure. Among various sensing techniques, field-effect transistors (FETs) with channels made of two-dimensional (2D) materials attract increasing attention for advantages such as label-free detection, fast response, easy operation, and capability of integration. With atomic thickness, 2D materials restrict the carrier flow within the material surface and expose it directly to the external environment, leading to efficient signal acquisition and conversion. This review summarizes the latest advances of 2D-materials-based FET (2D FET) sensors in a comprehensive manner that contains the material, operating principles, fabrication technologies, proof-of-concept applications, and prototypes. First, a brief description of the background and fundamentals is provided. The subsequent contents summarize physical, chemical, and biological 2D FET sensors and their applications. Then, we highlight the challenges of their commercialization and discuss corresponding solution techniques. The following section presents a systematic survey of recent progress in developing commercial prototypes. Lastly, we summarize the long-standing efforts and prospective future development of 2D FET-based sensing systems toward commercialization. [ABSTRACT FROM AUTHOR]

To realize graphene-based electronics, various types of graphene are required; thus, modulation of its electrical properties is of great importance. Theoretic studies show that intentional doping is a promising route for this goal, and the doped graphene might promise fascinating properties and widespread applications. However, there is no experimental example and electrical testing of the substitutionally doped graphene up to date. Here, we synthesize the N-doped graphene by a chemical vapor deposition (CVD) method. We find that most of them are few-layer graphene, although single-layer graphene can be occasionally detected. As doping accompanies with the recombination of carbon atoms into graphene in the CVD process, N atoms can be substitutionally doped into the graphene lattice, which is hard to realize by other synthetic methods. Electrical measurements show that the N-doped graphene exhibits an n-type behavior, indicating substitutional doping can effectively modulate the electrical properties of graphene. Our finding provides a new experimental instance of graphene and would promote the research and applications of graphene. [ABSTRACT FROM AUTHOR]

Describes the synthesis of monosilyl acetals through the reduction of alkyl esters with iBu2AlH and trapping of the resulting intermediate with N-(trimethylsilyl)imidazole. Formation of homoallylic alcohols or ethers via the Hosomi-Sakurai reaction; Epimerization or racemization of the monosilyl configuration; Mechanistic implications.

Two new diketopyrrolopyrrole-basedπ-conjugated copolymers(PDPP6T and PDPP7T) have been synthesized by Stille coupling polymerizationof 3,6-bis(5′-bromo-[2,2′-bithiophen]-5-yl)-2,5-bis(2-octyldodecyl)pyrrolo-[3,4-c]pyrrole-1,4(2H,5H)-dionewith α,α′-bis(trimethylstannyl)-bithiophene andα,α′-bis(trimethylstannyl)-terthiophene, respectively.The impressive high mobility of 3.94 cm2V–1s–1for the polymer with sextetthiophene (6T)and of 2.82 cm2V–1s–1for polymer with septetthiophene (7T) is acquired. It is found thatthe introduction of longer β-unsubstituted oliogothiophene unitin DPP-based copolymers has a great influence on the molecular weightand solubility of the DPP-oligothiophene copolymers that finally affectsthe organic thin-film transistor (OTFT) performances, indicating thata suitable number of thiophene group in β-unsubstituted oligothiopheneexists for such a kind of copolymer to exhibit the best OTFT performances.This work also reveals the significance in the design of D–Acopolymers for OTFTs through regulating the balance between π–πstacking of intermolecular chains and molecular weight as well assolubility of the rigid main chain. [ABSTRACT FROM AUTHOR]

We report the synthesis of two noveldonor–acceptor copolymerspoly{[N, N′-bis(alkyl)-1,4,5,8-naphthalenediimide-2,6-diyl-alt-5,5′-di(thiophen-2-yl)-2,2′-(E)-2-(2-(thiophen-2-yl)vinyl)thiophene]} (PNVTs) based onnaphthalenediimide (NDI) acceptor and (E)-2-(2-(thiophen-2-yl)vinyl)thiophenedonor. The incorporations of vinyl linkages into polymer backbonesmaintain the energy levels of the lowest unoccupied molecular orbitsat −3.90 eV, therefore facilitating the electron injection.Moreover, the energy levels of the highest occupied molecular orbitsincrease from −5.82 to −5.61 eV, successfully decreasingthe hole injection barrier. Atomic force microscopy measurements indicatethat PNVTs thin films exhibit larger polycrystalline grains comparedwith that of poly{[N, N′-bis(2-octyldodecyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt- 5,5′-(2,2′-bithiophene)}[P(NDI2OD-T2)], consistent with the stronger π–πstacking measured by grazing incidenceX-ray scatting. To optimize devices performance, field-effect transistors(FETs) with three devices configurations have been investigated. Theresults indicate that the electron mobility of the vinyl-containingPNVTs exhibit about 3–5 times higher than that of P(NDI2OD-T2).Additionally, the vinyl-linkages in PNVTs remarkably enhance ambipolartransport of their top-gate FETs, obtaining high hole and electronmobilities of 0.30 and 1.57 cm2V–1s–1, respectively, which are among the highest valuesreported to date for the NDI-based polymers. Most importantly, ambipolarinverters have been realized in ambient, exhibiting a high gain of155. These results provide important progresses in solution-processedambipolar polymeric FETs and complementary-like inverters. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis and characterizationoftwo new D-A-D molecules (E)-5,5′-bis(5-(benzo[b]thiophen-2-yl)thiophen-2-yl)-1,1′-bis(2-ethyl-hexyl)-[3,3′-bipyrrolylidene]-2,2′(1H,1′H)-dione (BTBPD) and (E)-5,5′-bis- (5-(benzo[b]furan-2-yl)thiophen-2-yl)-1,1′-bis(2-ethylhexyl)-[3,3′-bipyrrolylidene]-2,2′(1H,1′H)-dione (BFBPD). They entail bipyrrolylidene-2,2′(1H,1′H)-dione (BPD, known as Pechmann dye) as theelectron-accepting core that is flanked by two benzo[b]thiophene moieties and two benzo[b]furan moieties,respectively. Crystal structures of BTBPDand BFBPDprovide solid evidence for the intermolecular donor–acceptor(D-A) interactions, which are favorable for improving charge transportperformance. Organic field-effect transistors (OFETs) were preparedbased on thin films of BTBPDand BFBPDthroughsolution-processed technique. OFETs of BTBPDexhibitrelatively high hole mobility up to 1.4 cm2V–1s–1with high on/off ratio up to 106. In comparison, the hole mobility of OFETs with BFBPD(0.14 cm2V–1s–1) is relatively low, because of the poor thin-film morphology andlow molecular ordering, even after annealing. Thin-film morphologicaland XRD studies were carried out to understand the variation of holemobilities after annealing at different temperatures. The presentstudies clearly demonstrate the potentials of BPDthatis planar and polar as the electron-acceptor moiety to build D-A moleculesfor organic semiconductors with good performance. [ABSTRACT FROM AUTHOR]

Because of its atomic thickness, excellent properties, and widespread applications, graphene is regarded as one of the most promising candidate materials for nanoelectronics. The wider use of graphene will require processes that produce this material in a controllable manner. In this Account, we focus on our recent studies of the controllable chemical vapor deposition (CVD) growth of graphene, especially few-layer graphene (FLG), and the applications of this material in electronic devices. [ABSTRACT FROM AUTHOR]

A new diketopyrrolopyrrole-based π-conjugated copolymer(PDPP5T)with high molecular weight has been synthesized by Stille couplingpolymerization of 3,6-bis(5-bromothiophen-2-yl)-2,5-bis(2-octyldodecyl)pyrrolo-[3,4-c]pyrrole-1,4(2H,5H)-dionewith α,α′-bis(trimethylstannyl)-terthiophene. Itshole mobility without thermal annealing reaches 1.08 cm2V–1s–1, and a higher hole mobilityof 3.46 cm2V–1s–1is obtained annealed at 200 °C directly in an air atmosphere.This indicates that introducing a longer β-unsubstituted quinquethiophene(5T) unit into the main-chain of DPP-oligothiophene copolymer producesmuch pronounced p-type behavior and also reduces the steric hindranceof the bulk side-chain groups, which is favorable to enhance the molecularordering capability at low temperatures and improve the organic thin-filmtransistors (OTFT) performances. This work demonstrates that PDPP5Tis a promising material that can be applied to the cost-effectiveand large-scale production of OTFTs. [ABSTRACT FROM AUTHOR]

Two tetrabrominated intermediates obtained by bromination of naphthodithiophene in different solvents were used to construct novel highly π-extended butterfly-shaped heteroarenes 1–6, containing either an 8- or 10-fused ring. The solution-processed organic field-effect transistors based on compound 1exhibited promising device performance with a hole mobility of 0.072 cm2V–1s–1and a current on/off ratio of 106under ambient atmosphere. [ABSTRACT FROM AUTHOR]

Two structural isomers of six-fused-ring sulfur-containing molecules were synthesized as active materials for p-type organic field-effect transistors, and their optical and electrochemical properties were characterized. Field-effect transistors based on these compounds were fabricated to investigate the relationships between structures and semiconductor properties. [ABSTRACT FROM AUTHOR]

A series of new n-type copolymers based on perylene diimide(PDI) or naphthalene diimide (NDI) and phenothiazine (PTZ) with differentside chain length and molecular weight have been designed and synthesizedby Pd-catalyzed Suzuki coupling polymerization with or without phase-transfercatalyst Aliquat 336. The effects of main chain, side chain, and molecularweight on the thermal, optical, electronic, and charge transport propertiesof the polymers have been investigated. Aliquat 336 improves molecularweight as well as reduces polydispersity index of the polymers. Allthe polymers exhibit a broad absorption extending from 300 to 900nm. The main chain and side chain structure and molecular weight haveminor effects on the HOMO (−5.8 to −5.9 eV) and LUMO(−3.7 to −3.8 eV) levels of the polymers. n-Channelfield-effect transistors with bottom-gate top-contact geometry basedon these copolymers exhibit electron mobilities as high as 0.05 cm2V–1s–1and on/off ratiosas high as 105in nitrogen, which are among the best reportedfor rylene diimide-based polymers under the same test conditions. [ABSTRACT FROM AUTHOR]

Four X-shaped oligothiophenes with different conjugation length were investigated as novel electron donors in single-layer bulk-heterojunction solar cells. The UV−vis absorption spectra of blends of compounds 1−4 with 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C61 show a remarkably red shift and broadening with increasing thiophene number at each of the four branches. The performance of the photovoltaic cells varied significantly with molecular structures of the four oligothiophenes. Conversion efficiencies increased from 0.008% to 0.8% with changing the electron donors from 1 to 4. The maximum incident photon-to-current conversion efficiency of the device based on 4 reaches 31.6%, much higher than those of three other compounds 1−3. Remarkable improvement of the device performance was achieved with increasing the substituted thiophene number. The results show that the photovoltaic effect is dependent on the structural characteristics and the film forming abilities of the X-shaped thiophenes. [ABSTRACT FROM AUTHOR]

A simple method to decorate the multiwalled carbon nanotubes (MWCNTs) with ZnS nanospheres has been developed. The method involves ultrasonic pretreatment and heat treatments of MWCNTs, zinc chloride, and thiourea in ethanol. The heterostructures have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Comparative experiments show that both ultrasonic treatment and heat treatment are necessary for synthesizing the MWCNTs/ZnS heterostructures. Moreover, a photoluminescence spectrum shows that the MWCNTs/ZnS heterostructures feature a broad blue emission at about 430 nm, indicating that there exists significant ground-state interaction between ZnS nanospheres and MWCNTs. Meanwhile, the current−voltage characteristic of the MWCNTs/ZnS exhibits clear rectifying behavior, revealing charge transfer between MWCNTs and ZnS nanospheres. [ABSTRACT FROM AUTHOR]