•The CuPc nanowire FETs with gas dielectric are fabricated and modified with Ph5T2.•The pristine and modified CuPc FET respectively show high response to H2S and NO2.•The response to H2S and NO2 are superior to most reported organic gas sensors.•The selectivity of CuPc NW to H2S and NO2 can be modulated by Ph5T2 modification.•The controllable selectivity is investigated based on interfacial charge transfer.A dinaphtho[3,4-d:3′,4′-d′]benzo[1,2-b:4,5-b′]dithiophene (Ph5T2)-modified copper phthalocyanine (CuPc) single crystal nanowire field-effect transistor (FET) with gas dielectric was fabricated as an organic gas sensor. This device exhibits the high response and the excellent controllable selectivity at room temperature. Its detection limit for NO2, NO, and H2S is down to sub-ppm level. Prior to surface modification, the CuPc nanowire FET shows the response as high as 1088% to 10 ppm H2S, but only 97.5% to 10 ppm NO2. After Ph5T2 modification, the response to 10 ppm H2S is decreased by one order of magnitude, but is dramatically improved up to 460% to 10 ppm NO2. The responses towards H2S and NO2 respectively for pristine and the modified sensor are higher than those of most reported organic sensors. The gas-sensing results reveal that Ph5T2 modification can transform the selectivity of the sensor from H2S to NO2. The controllable modulation of gas selectivity is related to the formed organic heterojunctions between CuPc and Ph5T2, where the hole carriers of CuPc nanowire are modulated by these heterojunctions, resulting in the changed adsorption behavior towards different gases.Download high-res image (183KB)Download full-size image

High-performance rubrene single-crystal field-effect transistors (SCFETs) with bottom-gate bottom-contact configuration were successfully fabricated on both planar and curved surfaces based on a photolithography-compatible conformal electrode. This electrode not only provides versatile precise patterns for device design, but also eliminates the device differences by the fabrication of multiple devices based on one single crystal, which is very favorable for studies of the intrinsic properties and integration of organic devices. The resulting rubrene SCFETs show excellent electrical properties with good device uniformity, zero hysteresis, a device yield as high as 92%, and a field-effect mobility of over 20 cm2 V−1 s−1 on different surfaces including a banknote, a pencil, and a 0.7 cm glass sphere. The high electrical performance in our bottom-contact devices can be attributed to the nondestructive interface contact and eliminated electrode steps. Such a soft coplanar electrode provides a preferred configuration for bottom-contact organic field-effect transistors (OFETs), facilitating the studies on the fundamental properties of organic transistors, and showing strong potential for the development of large-scale commercial organic transistor fabrication.

A strongly electron-withdrawing benzo[c][1,2,5]oxadiazole (BOZ) unit, as the second electron acceptor segment, is incorporated into the naphthalenediimide (NDI) based polymer backbone for the first time. Therefore, a unipolar n-type polymer semiconductor (PNBO) with a regioregular A1–D–A2–D configuration is developed successfully. It is found that BOZ-containing polymer PNBO not only has a deep-lying LUMO energy level of ca. −4.0 eV, which facilitates electron-injection from an Au electrode into the active layer, but also possesses a deep enough low HOMO energy level of −5.9 eV for blocking hole-injection. The carrier transporting performance of PNBO is characterized by solution-processable polymeric field-effect transistors (PFETs). These results demonstrate that a smooth surface morphology and a compact solid stacking endow PNBO with excellent unipolar n-type electron-transporting characteristics; a highest electron mobility of up to 2.43 cm2 V−1 and an excellent shelf storage with a negligible decay in 70 days are achieved.

We demonstrate a novel solution-based assembly method using a writing brush to realize the controllable fabrication of highly-oriented and large-scale TCNQ single-crystal microwire arrays. The arrays can not only be grown on conventional rigid substrates, such as Si, Si/SiO2 and low-cost glass, but also on nonconventional substrates, which include flexible polyethylene terephthalate (PET), curved glass hemispheres and commercially available plastic contact lenses. Their morphology is optimized by tuning solution concentration, substrate temperature, brush type, inclination angles and pressure of the brush. The length of the microwire arrays can extend to the millimeter level, and their preferential orientation is perpendicular to the lengthwise direction of the brush hair. The coverage area of microwire arrays with a consistent orientation can reach 1.5 × 2.0 mm2 and the success ratio is as high as 93%. Based on these microwire arrays, devices on different substrates, including rigid Si/SiO2 and flexible PET, can be easily realized in one step. The anisotropic transport of TCNQ crystals is studied with respect to the concentration controlled morphology. All these results illustrate the broad application prospects of this facile writing-brush method in the growth of large-scale, high-quality organic micro/nanowires for integration into flexible organic semiconductor devices and circuits.

•The high-sensitive field-effect H2S sensors are realized based on ultrathin Ph5T2 single-crystal microplates.•The response is as high as 1.2 × 106% in 50 ppm H2S.•The response of H2S sensor is three orders of magnitude higher than that of the most reported semiconductor gas sensors.•The ultrathin Ph5T2 single-crystal microplates provide efficient ways for the analytes' activities within the conductive channel.Based on ultrathin dinaphtho[3,4-d:3′,4′-d′]benzo[1,2-b:4,5-b′]dithiophene (Ph5T2) single-crystal microplates, the highly sensitive organic field-effect H2S sensors are realized at room temperature. The response is as high as 1.2 × 106% in 50 ppm H2S. This value is extremely high for H2S sensors, and is three orders of magnitude higher than that of the most reported semiconductor gas sensors. The response/recovery time is respectively as low as 2 min and 1 min in 50 ppm H2S. The detect limitation is as low as 0.5 ppm. The ultrathin single-crystal microplates provide direct and efficient ways for the analytes' activities within the conducting channel, and therefore mainly account for the improved sensing performance. The excellent sensing performance of ultrathin Ph5T2 single-crystal microplate transistors reveals the capacity of developing highly sensitive room-temperature sensors.

Correction for ‘Individual single-crystal nanowires as electrodes for organic single-crystal nanodevices’ by Guorui Wang et al., J. Mater. Chem. C, 2015, DOI: 10.1039/c5tc01920f.

Conductive, transparent, and flexible SnO2:Sb single-crystal nanowires are shown as electrodes for F16CuPc single-crystal nanowire devices on flexible plastic, which includes anisotropic-transport OFETs, electrode-movable OFETs, and p–n junction photovoltaic devices. The SnO2:Sb nanowires provide a good energy level match and excellent soft contact with F16CuPc nanowires, leading to multifaceted applications of the SnO2:Sb nanowire in nanowire electronics and optoelectronics, as well as high device performance. Combined with their good size compatibility, these results show that the conductive SnO2:Sb single-crystal nanowire opens a window into the fundamental understanding of the intrinsic properties of highly ordered organic semiconductors, optimization and miniaturization of organic nanocircuits, and development of new-generation flexible organic nanodevices.

•Fabrication process: simple and novel non-solution method to integrate the GNR formation and the FET fabrication, minimizing the fabrication steps.•Size-controlled: the channel length and width of the FET can be controlled by the SnO2 nanoribbons.•Novel field-effect properties: presenting the promising ambipolar in air ambient and high mobility.•The critical width of GNR up to 330 nm: the GNR device with the width up to 330 nm still presents the dramatic semiconductor property.Conventional graphene nanoribbon (GNR) field-effect transistor (FET) fabrication involved the wet process with the separated nanoribbon formation and device fabrication. Here, we demonstrate one simple and novel non-solution method to integrate the GNR formation and the FET fabrication, where a gold film is used as mask for electrode deposition, following by using a SnO2 nanoribbon as mask for the formation of GNR. The channel length and width can be controlled by the widths of the gold film and the SnO2 nanoribbon, respectively. It is found that the GNR with the width up to 330 nm presents the promising ambipolar field-effect properties in air ambient, the hole and electron mobilities are respectively as high as 904 and 703 cm2 V−1 s−1, which benefits from the all dry process for both GNR fabrication and device fabrication.The size-controlled ambipolar graphene nanoribbon transistors have been obtained by an all-dry mask method.

A multiple drop-casting method of growing the ultralong dibenzo-tetrathiafulvalene (DB-TTF) micro/nanowire arrays has been developed which has the success ratio as high as 94%. This method enables the arrays with a length over a few hundreds of micrometers to locate between droplets with the definite orientation. The width of the micro/nanowires is controlled via tuning the concentration of DB-TTF solution in dichloromethane. The large-scale arrays can be grown onto Si, SiO2, glass, and the flexible polyethylene terephthalate (PET) substrates. These results show the promising potential of this facile solution-based process for the growth of the high-quality organic micro/nanowires, the fabrication of high-performance and flexible devices, and the fabrication of controlled assemblies of nanoscale circuits for fundamental studies and future applications.

•We developed the drop-casting method via saturated solvent atmosphere, and obtained the single-crystal TTF microwire arrays.•Based on this method, the success ratio to form TTF microwire arrays is as high as 86%.•This method can improve the crystalline quality and success ratio of many soluble organic microwire arrays, such as TTF, DB-TTF and TCNQ.•The TTF microwire array FETs were fabricated based on this method, suggesting the potential of this method in electronic applications.We developed a drop-casting method to grow the well-aligned single-crystal tetrathiafulvalene (TTF) microwire arrays with success ratio as high as 86%. The key improvement over the earlier study is that the substrate is placed in an apparatus which is filled with the saturated solvent vapor at room temperature. The saturated solvent atmosphere ensures stable environment and adequate time to form the arrays with high success ratio, and to dramatically improve the crystalline quality. Combined with the optimized concentration, the highly ordered single-crystal TTF microwire arrays are obtained. Based on these microwire arrays, the assembly of devices can be easily realized in one step. These results show the potential of this facile method to form the high-quality arrays, and the assemblies of nanoscale circuits for fundamental studies and future applications.The large-scale, well-aligned and single-crystal tetrathiafulvalene (TTF) microwire arrays have been obtained by the developed drop-casting method in the saturated solvent atmosphere with high success ratio.

The ultralong ZnO nanowires have been obtained by using ZnO and graphite as the mixture source via the catalyst-free vapor–solid (VS) process at 917 °C. The ZnO nanowires are over 100 μm in length and ∼100–300 nm in diameter with uniform hexagonal cross section. The single ultralong ZnO nanowire grows on the top of one ZnO nanotower with the length of ∼5 μm and the diameter of ∼600 nm. The formation of a ZnO hard layer on the surface of the mixture source is responsible for the abrupt morphology change and the growth of the ultralong nanowires. The local concentration of the Zn vapor and the oxygen are found to be critical for the formation of the ultralong ZnO nanowires. The catalyst-free growth of the ultralong ZnO nanowire was carried out with good repeatability in a low-cost quartz tube electric resistance furnace with the temperature lower than 1000 °C, showing a promising potential for the development of the ZnO based nanodevices and nanocircuits.

We demonstrate a novel solution-based assembly method using a writing brush to realize the controllable fabrication of highly-oriented and large-scale TCNQ single-crystal microwire arrays. The arrays can not only be grown on conventional rigid substrates, such as Si, Si/SiO2 and low-cost glass, but also on nonconventional substrates, which include flexible polyethylene terephthalate (PET), curved glass hemispheres and commercially available plastic contact lenses. Their morphology is optimized by tuning solution concentration, substrate temperature, brush type, inclination angles and pressure of the brush. The length of the microwire arrays can extend to the millimeter level, and their preferential orientation is perpendicular to the lengthwise direction of the brush hair. The coverage area of microwire arrays with a consistent orientation can reach 1.5 × 2.0 mm2 and the success ratio is as high as 93%. Based on these microwire arrays, devices on different substrates, including rigid Si/SiO2 and flexible PET, can be easily realized in one step. The anisotropic transport of TCNQ crystals is studied with respect to the concentration controlled morphology. All these results illustrate the broad application prospects of this facile writing-brush method in the growth of large-scale, high-quality organic micro/nanowires for integration into flexible organic semiconductor devices and circuits.

Conductive, transparent, and flexible SnO2:Sb single-crystal nanowires are shown as electrodes for F16CuPc single-crystal nanowire devices on flexible plastic, which includes anisotropic-transport OFETs, electrode-movable OFETs, and p–n junction photovoltaic devices. The SnO2:Sb nanowires provide a good energy level match and excellent soft contact with F16CuPc nanowires, leading to multifaceted applications of the SnO2:Sb nanowire in nanowire electronics and optoelectronics, as well as high device performance. Combined with their good size compatibility, these results show that the conductive SnO2:Sb single-crystal nanowire opens a window into the fundamental understanding of the intrinsic properties of highly ordered organic semiconductors, optimization and miniaturization of organic nanocircuits, and development of new-generation flexible organic nanodevices.

Correction for ‘Individual single-crystal nanowires as electrodes for organic single-crystal nanodevices’ by Guorui Wang et al., J. Mater. Chem. C, 2015, DOI: 10.1039/c5tc01920f.

A strongly electron-withdrawing benzo[c][1,2,5]oxadiazole (BOZ) unit, as the second electron acceptor segment, is incorporated into the naphthalenediimide (NDI) based polymer backbone for the first time. Therefore, a unipolar n-type polymer semiconductor (PNBO) with a regioregular A1–D–A2–D configuration is developed successfully. It is found that BOZ-containing polymer PNBO not only has a deep-lying LUMO energy level of ca. −4.0 eV, which facilitates electron-injection from an Au electrode into the active layer, but also possesses a deep enough low HOMO energy level of −5.9 eV for blocking hole-injection. The carrier transporting performance of PNBO is characterized by solution-processable polymeric field-effect transistors (PFETs). These results demonstrate that a smooth surface morphology and a compact solid stacking endow PNBO with excellent unipolar n-type electron-transporting characteristics; a highest electron mobility of up to 2.43 cm2 V−1 and an excellent shelf storage with a negligible decay in 70 days are achieved.