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Heterocycle‐linked phthalocyanine‐based COFs with close‐packed π–π conjugated structures are a kind of material with intrinsic electrical conductivity, and they are considered to be candidates for photoelectrical devices. Previous studies have revealed their applications for energy storage, gas sensors, and field‐effect transistors. However, their potential application in photodetector is still not fully studied. The main difficulty is preparing high‐quality films. In our study, we found that our newly designed benzimidazole‐linked Cu (II)‐phthalocyanine‐based COFs (BICuPc‐COFs) film can hardly formed with a regular aerobic oxidation method. Therefore, we developed a transfer dehydrogenation method with N‐benzylideneaniline (BA) as a mild reagent. With this in hand, we successfully prepared a family of high crystalline BICuPc‐COFs powders and films. Furthermore, both of these new BICuPc‐COFs films showed high electrical conductivity (0.022–0.218 S/m), higher than most of the reported COFs materials. Due to the broad absorption and high conductivity of BICuPc‐COFs, synaptic devices with small source‐drain voltage (VDS=1 V) were fabricated with response light from visible to near‐infrared. Based on these findings, we expect this study will provide a new perspective for the application of conducting heterocycle‐linked COFs in synaptic devices. [ABSTRACT FROM AUTHOR]

Biomarkers are primary indicators for precise diagnosis and treatment. The early identification of health biomarkers has been sustained by the evolutionary success in sensor technologies. Among them, graphene field‐effect transistor (GFET) biosensors have exhibited major advantages such as an ultrashort response time, high sensitivity, easy operation, capability of integration, and label‐free detection. Owing to the atomic thickness, graphene restricts charge carrier flow merely at the material surface and responds to foreign stimuli directly, leading to effective signal acquisition and transmission. Here, this review summarizes the latest advances in GFET biosensors in a comprehensive manner that contains the device design, working principle, surface functionalization, and proof‐of‐concept applications. It provides a comprehensive survey of GFET biosensors with regard to biomarker analysis at the single‐device level and integrated prototypes that include wearable sensors, biomimetic systems, healthcare electronics, and diagnostic platforms. Moreover, there is discussion on the long‐standing research efforts and outlook for the future development of GFET sensor systems from lab to fab. [ABSTRACT FROM AUTHOR]

For epidemic prevention and control, molecular diagnostic techniques such as field‐effect transistor (FET) biosensors is developed for rapid screening of infectious agents, including Mycobacterium tuberculosis, SARS‐CoV‐2, rhinovirus, and others. They obtain results within a few minutes but exhibit diminished sensitivity (<75%) in unprocessed biological samples due to insufficient recognition of low‐abundance analytes. Here, an electro‐enhanced strategy is developed for the precise detection of trace‐level infectious agents by liquid‐gate graphene field‐effect transistors (LG‐GFETs). The applied gate bias preconcentrates analytes electrostatically at the sensing interface, contributing to a 10‐fold signal enhancement and a limit of detection down to 5 × 10−16 g mL−1 MPT64 protein in serum. Of 402 participants, sensitivity in tuberculosis, COVID‐19 and human rhinovirus assays reached 97.3% (181 of 186), and specificity is 98.6% (213 of 216) with a response time of <60 s. This study solves a long‐standing dilemma that response speed and result accuracy of molecular diagnostics undergo trade‐offs in unprocessed biological samples, holding unique promise in high‐quality and population‐wide screening of infectious diseases. [ABSTRACT FROM AUTHOR]

Ladder‐like aromatic diketones (LADK), which possess a coplanar π‐extended geometry, a high electron deficiency as well as various attractive optoelectronic properties, are demonstrated as the promising candidates in building small‐molecule organic electron‐transporting materials, yet reports on direct integration of these structural motifs into n‐type polymers are rarely accessed. Herein, it is demonstrated that a possibility of realizing unipolar n‐type characteristics of such acceptor system by developing two novel donor–acceptor type polymers, in which the newly developed LADK unit, named as 3,8‐bis(2‐decyltetradecyl)‐5,10‐difluoro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐4,9‐dione (FIDTO‐R), is adopted as the acceptor segments. The resulting polymers present deep‐lying unoccupied molecular orbital levels (as low as −3.84 eV), compact π–π stacking (d‐spacing, ≈3.57 Å) coupled with uniform nanofiber‐like surface morphology. All these factors contribute to excellent unipolar n‐type characteristics with high electron mobilities of 0.27 and 1.01 cm2 V−1 s−1, together with high inverter gain values of 141 and 80, respectively. The recorded values are among the best in n‐type polymer field‐effect transistors and associated inverter circuits. These findings unambiguously reveal that the as‐prepared FIDTO‐R and its analog LADK derivatives are another type of excellent building blocks for the construction of high‐mobility n‐type polymers. [ABSTRACT FROM AUTHOR]

D‐A conjugated polymers P1 and P2 are synthesized by copolymerizing bisthiophene‐fused diketopyrrolopyrrole (4,11‐bis(2‐decyltetradecyl)‐7H,14H‐thieno[3',2':7,8]‐indolizino[2,1‐a]thieno[3,2‐g]indolizine‐7,14‐dione, BTI) with terthiophene and thiophene‐benzothiadiazole‐thiophene, respectively. Molecular packing is characterized by X‐ray diffraction. The film morphology is characterized by atomic force and scanning electron microscopy. The vertical phase separation is characterized by XPS. The mechanism of film morphology formation is explained from intermolecular interaction, kinetics, and surface free energy. The spin‐coated films of polymers blended with PC71BM are served as semiconductor layers in near‐infrared (NIR) phototransistors. The impact of morphology on optoelectronic performance is analyzed. The mobility of organic field effect transistors based on P1 or P2 thin films remains constant with the addition of PC71BM with weight ratio being less than 50%. The main reason is that π–π stacking in both P1 and P2 thin films is at all directions and PC71BM does not disturb the charge percolation path. Benzothiadiazole in P2 enables stronger mutual attraction between P2 and PC71BM, and therefore large contact area between P2 and PC71BM forms in the heterojunction. The photoresponsivity improves by 2 times for NIR phototransistors based on P2/PC71BM when decreasing light intensity from 63 to 1.8 µW cm‐2. The above results suggest a feasible conjugated polymer design rule for high sensitivity NIR phototransistors. [ABSTRACT FROM AUTHOR]

Owing to its atomic thickness, thermal dissipation is one significant bottleneck for the practical application of graphene in electronics. Here, it is demonstrated that a high‐quality ultraclean van der Waals interface can be obtained after modifying the SiO2/Si substrate with hexagonal‐boron nitride (h‐BN) by plasma‐enhanced chemical vapor deposition, which improves the mobility and the interfacial thermal dissipation of graphene field‐effect transistors (FETs). On h‐BN, interfacial thermal resistance decreases by more than 77% and the saturated power density of graphene FETs increases by 2–3‐folds to 3.45 × 105 W cm−2, higher than the power density of current CPUs (≈100 W cm−2), demonstrating its potential in future graphene‐based electronics. [ABSTRACT FROM AUTHOR]

Due to the complexity of detection environments, field‐effect transistor (FET) sensors face the problem of fouling in practical applications. Existing antifouling strategies normally block the sensing sites and decrease the detection sensitivity. It remains a great challenge to achieve antifouling and sensitive detection. Here, a strategy is developed to use covalent organic frameworks (COFs) as the sensing interface. Owing to their unique crystalline mesoporous structure, the COFs not only encapsulate and prevent the channel from being fouled but also provide a large specific surface area modified with receptors. This approach enables the detection of 10−10m Hg2+ within 50 ms in a ≈30 ppm poly‐(3,4‐ethylenedioxythiophene):poly‐(styrenesulfonate) solution and weak neural potential signals in complex bio‐environment, which is among the best performance for antifouling FET sensors. The COF interface enables highly sensitive and antifouling detection together with a fast response and large response range, which shows its great potential in high‐performance antifouling FET sensors. [ABSTRACT FROM AUTHOR]

Graphene has attracted great interest in the past decade due to its unique band structure and physical properties such as quantum electronic transport, extremely high mobility, high elasticity and optical properties. Graphene is generally obtained by mechanical exfoliation, epitaxial growth, chemical vapor deposition and chemical synthesis approaches, wherein the reduction of graphene oxide (GO) is a practical approach to synthesize large‐scale graphene. Via reduction, highly conductive reduced graphene oxide (RGO) can be obtained, which has electrical and optical properties analogous to those of graphene. However, Field‐effect transistors (FETs) based RGO typically exhibit p‐type in ambient rather than the ambipolar behavior of intrinsic graphene, due to the doping effect induced by substrate and the air. Meanwhile, large hysteresis accompanies with the p‐type transistor. Here, a self‐assembled monolayer (SAM) of octadecyltrichlorosilane (OTS)‐RGO heterostructure is developed, in which RGO is sandwiched between OTS SAMs. The heterostructure passivates the RGO device and eliminates the doping of graphene from the surroundings. The obtained RGO FETs exhibit air‐stable symmetric ambipolar behavior with Dirac point at 0 V gate voltage and negligible hysteresis. This approach will also be applicable to pristine graphene and other two‐dimensional materials to obtain the intrinsic properties under ambient conditions, thereby promoting the research and applications of two‐dimensional materials. Monolayer of octadecyltrichlorosilane (OTS) is successfully self‐assembled on the surface of reduced graphene oxide (RGO), and RGO‐OTS SAM heterostructure is fabricated for FET devices, which exhibits air stable intrinsic symmetric ambipolar field‐effect behavior with the Dirac point at the 0 V gate voltage and negligible hysteresis. [ABSTRACT FROM AUTHOR]

Organic field-effect transistors (OFETs) have received considerable attention across the world due to their potential applications in integrated circuits for large-area, flexible and low-cost electronics, and a series of breakthroughs in their research have been made in the past decade. Although numerous novel organic semiconductive materials with outstanding properties have been synthesized, the fabrication of OFETs and the investigation of amorphous polymer insulators (APIs) are attracting more and more research interest due to their significance in semiconductor growth, charge transport and device stability. In this review, an introduction to APIs and OFETs is given, and the following aspects are then successively discussed: commonly used APIs in OFETs, applications of API in high-performance OFETs, low-energy-consumption OFETs, functional OFETs, and self-healing OFETs. In the last section, a projection of some future trends for APIs in OFETs is presented. [ABSTRACT FROM AUTHOR]

Benzopyrazinoisoindigo, a pigment reported 40 years ago, should be a good candidate for n-type semiconductors if the reported structure is correct. Reinvestigation of this molecule revealed that it is actually (4 H,4′ H)-benzopyrazinoisoindigo, which could be considered as the reduced form of benzopyrazinoisoindigo, and hence, it is a good candidate for p-type semiconductors. The route toward the synthesis of this molecule was optimized, and a mechanism was accordingly proposed. A field-effect transistor based on this material showed a hole mobility up to 2.5 × 10-2 cm2 V-1 s-1. [ABSTRACT FROM AUTHOR]

'Regioselectivity deposition' method is developed to pattern silver electrodes facilely and efficiently by solution-process with high resolution (down to 2 μm) on different substrates in A4 paper size. With the help of this method, large-area, flexible, high-performance polymer field-effect transistors based on the silver electrodes and polyimide insulator are fabricated with bottom-contact configuration by all-solution processes. The polymer devices exhibit high performance with average field-effect mobility over 1.0 cm2 V−1 s−1 (the highest mobility up to 1.5 cm2 V−1 s−1) and excellent environmental stability and flexibility, indicating the cost effectiveness of this method for practical applications in organic electronics. [ABSTRACT FROM AUTHOR]

In this study, we successfully designed and synthesized a novel phenanthro[1,10,9,8- c,d,e,f,g]carbazole ( PCZ)-based copolymer poly[ N-(2-octyldodecyl)-4,8-phenanthro[1,10,9,8- c,d,e,f,g]carbazole- alt-2,5-dihexadecyl-3,6-di(thiophen-2-yl)pyrrolo[3,4- c]pyrrole-1,4(2 H,5 H)-dione] ( PPDPP) with an extended π-conjugation along the vertical orientation of polymer main chain. This polymer exhibited excellent solubility in common solvent and high thermal stability, owning good properties for solution-processed field-effect transistors (FETs). Besides, absorption spectra demonstrated that annealing PPDPP thin films led to obviously red-shifted maxima, indicating the formations of aggregation or orderly π-π stacking in their solid-state films. X-ray diffraction measurements indicated the crystallinity of PPDPP thin films was enhanced after high temperature annealing, which was favorable for charge transport. The solution-processed PPDPP-based FET devices were fabricated with a bottom-gate/bottom-contact geometry. A high hole mobility of up to 0.30 cm2/Vs and a current on/off ratio above 105 had been demonstrated. These results indicated that the copolymers constructed by this kind of ladder-type cores could be promising organic semiconductors for high-performance FET applications. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]