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1.
We have demonstrated the controlled synthesis of conducting‐polymer microcontainers through the electrochemical generation of surfactant (i.e., β‐naphthalenesulfonic acid, β‐NSA)‐stabilized H2 gas bubbles on the working electrode, followed by electrochemical polymerization of pyrrole around the wall of the “soap‐bubble” template. It was noticed that the density, shape, and wall thickness of the polypyrrole microcontainers thus prepared could be regulated by controlling the electrochemical potential applied for the generation of H2 gas and the experimental conditions (e.g., the surfactant concentration, number of the cyclic voltammetric scanning) for the electropolymerization of pyrrole. By pre‐patterning the working electrode surface with non‐conducting polymers using microcontact printing (μCP) or plasma patterning, we have also produced conducting‐polymer microcontainers in a patterned fashion. Furthermore, potential applications of the patterned and non‐patterned conducting‐polymer microcontainers have been demonstrated; for example, through the encapsulation of appropriate fluorescence‐labeled molecules (e.g., fluorescein cadaverin) into the conducting‐polymer microcontainers by sealing their opened mouths with sequential electropolymerization of pyrrole. The resulting closed microcontainers could then be used for controlled releases.  相似文献   

2.
Regioregular poly(3‐hexyl thiophene) (RR P3HT) is drop‐cast to fabricate field‐effect transistor (FET) devices from different solvents with different boiling points and solubilities for RR P3HT, such as methylene chloride, toluene, tetrahydrofuran, and chloroform. A Petri dish is used to cover the solution, and it takes less than 30 min for the solvents to evaporate at room temperature. The mesoscale crystalline morphology of RR P3HT thin films can be manipulated from well‐dispersed nanofibrils to well‐developed spherulites by changing solution processing conditions. The morphological correlation with the charge‐carrier mobility in RR P3HT thin‐film transistor (TFT) devices is investigated. The TFT devices show charge‐carrier mobilities in the range of 10–4 ~ 10–2 cm2 V–1 s–1 depending on the solvent used, although grazing‐incidence X‐ray diffraction (GIXD) reveals that all films develop the same π–π‐stacking orientation, where the <100>‐axis is normal to the polymer films. By combining results from atomic force microscopy (AFM) and GIXD, it is found that the morphological connectivity of crystalline nanofibrils and the <100>‐axis orientation distribution of the π–π‐stacking plane with respect to the film normal play important roles on the charge‐carrier mobility of RR P3HT for TFT applications.  相似文献   

3.
A general method is proposed to produce oriented and highly crystalline conducting polymer layers. It combines the controlled orientation/crystallization of polymer films by high‐temperature rubbing with a soft‐doping method based on spin‐coating a solution of dopants in an orthogonal solvent. Doping rubbed films of regioregular poly(3‐alkylthiophene)s and poly(2,5‐bis(3‐dodecylthiophen‐2‐yl)thieno[3,2‐b ]thiophene) with 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ) yields highly oriented conducting polymer films that display polarized UV–visible–near‐infrared (NIR) absorption, anisotropy in charge transport, and thermoelectric properties. Transmission electron microscopy and polarized UV–vis–NIR spectroscopy help understand and clarify the structure of the films and the doping mechanism. F4TCNQ? anions are incorporated into the layers of side chains and orient with their long molecular axis perpendicular to the polymer chains. The ordering of dopant molecules depends closely on the length and packing of the alkyl side chains. Increasing the dopant concentration results in a continuous variation of unit cell parameters of the doped phase. The high orientation results in anisotropic charge conductivity (σ) and thermoelectric properties that are both enhanced in the direction of the polymer chains (σ = 22 ± 5 S cm?1 and S = 60 ± 2 µV K?1). The method of fabrication of such highly oriented conducting polymer films is versatile and is applicable to a large palette of semiconducting polymers.  相似文献   

4.
Here, reactive imprint lithography (RIL) is introduced as a new, one‐step lithographic tool for the fabrication of large‐area topographically patterned, chemically activated polymer platforms. Films of polystyrene‐block‐poly(tert‐butyl acrylate) (PS‐b‐PtBA) are imprinted with PDMS master stamps at temperatures above the corresponding glass transition and chemical deprotection temperatures to yield structured films with exposed carboxylic acid and anhydride groups. Faithful pattern transfer is confirmed by AFM analyses. Transmission‐mode FTIR spectra shows a conversion of over 95% of the tert‐butyl ester groups after RIL at 230 °C for 5 minutes and a significantly reduced conversion to anhydride compared to thermolysis of neat films with free surfaces in air or nitrogen. An enrichment of the surface layer in PS is detected by angle‐resolved X‐ray photoelectron spectroscopy (XPS). In order to demonstrate application potentials of the activated platforms, a 7 nm ± 1 nm thick NH2‐terminated PEG layer (grafting density of 0.9 chains nm?2) is covalently grafted to RIL‐activated substrates. This layer reduces the non‐specific adsorption (NSA) of bovine serum albumin by 95% to a residual mass coverage of 9.1 ± 2.9 ng cm?2. As shown by these examples, RIL comprises an attractive complementary approach to produce bio‐reactive polymer surfaces with topographic patterns in a one‐step process.  相似文献   

5.
Herein a novel synthetic route is described for the production of thermally stable, structurally well‐defined two‐dimensional (2D) hexagonal mesoporous nanocrystalline anatase (meso‐nc‐TiO2), with a large pore diameter, narrow pore‐size distribution, high surface area, and robust inorganic walls comprised of nanocrystalline anatase. The synthetic approach involves the evaporation‐induced co‐assembly of a non‐ionic amphiphilic triblock‐copolymer template and titanium tetraethoxide, but with a pivotal change in the main solvent of the system, where the commonly used ethanol is replaced with 1‐butanol. This seemingly minor modification in solvent type from ethanol to 1‐butanol turns out to be the key synthetic strategy for achieving a robust, structurally well‐ordered meso‐nc‐TiO2 material in the form of either thick or thin films. The beneficial “solvent” effect originates from the higher hydrophobicity of 1‐butanol than ethanol, enhancing microphase separation and templating, lower critical micelle concentration of the template in 1‐butanol, and the ability to increase the relative concentration of the inorganic precursor to template in the co‐assembly synthesis. Moreover, thin films with dimensions of several centimeters that are devoid of cracks down to the length scale of the mesostructure itself, having high porosity, well‐defined mesostructural features, and semi‐crystalline pore walls were straightforwardly and reproducibly obtained as a result of the physicochemical property advantages of 1‐butanol over ethanol within our synthesis scheme.  相似文献   

6.
This paper reports the first example of the fabrication of KNO3, K2CO3, CuSO4, NaOH, and mixed‐inorganic‐salt (KNO3 and KOH) patterns using a transfer‐printing (TP) technique. The transfer quality is found to be related to the concentration of the salt solutions. By varying the immersion time, it is possible to control the heights of the raised features of the transfer‐printed salts from the nanoscale to the submicrometer scale. Utilizing these inorganic salts as water‐soluble masks for microfabrication is demonstrated using patterned NaOH films. The use of water as a developer solvent demonstrates the potential utility of the patterning of inorganic salts as a low‐cost, simple, and, more importantly, environmentally friendly route towards accurate patterning of different materials.  相似文献   

7.
High‐performance polymer memory is fabricated using blends of ferroelectric poly(vinylidene‐fluoride‐trifluoroethylene) (P(VDF‐TrFE)) and highly insulating poly(p‐phenylene oxide) (PPO). The blend films spontaneously phase separate into amorphous PPO nanospheres embedded in a semicrystalline P(VDF‐TrFE) matrix. Using low molecular weight PPO with high miscibility in a common solvent, i.e., methyl ethyl ketone, blend films are spin cast with extremely low roughness (Rrms ≈ 4.92 nm) and achieve nanoscale phase seperation (PPO domain size < 200 nm). These blend devices display highly improved ferroelectric and dielectric performance with low dielectric losses (<0.2 up to 1 MHz), enhanced thermal stability (up to ≈353 K), excellent fatigue endurance (80% retention after 106 cycles at 1 KHz) and high dielectric breakdown fields (≈360 MV/m).  相似文献   

8.
A nanoaggregated dispersed red 1‐grafted poly(N‐vinylcarbazole) (abbreviated PVDR) is self‐assembled via ππ stacking interactions of the carbazole groups in the polymer system after adding a solution of PVDR in N,N‐dimethylformamide to dichloromethane. Upon self‐assembly, the nanoaggregated PVDR film displays helical columnar stacks with large grain sizes, whereas a non‐aggregated PVDR film exhibits an amorphous morphology with smaller grain size. A write‐once read‐many‐times (WORM) memory device is shown whereby a pre‐assembled solution of PVDR is spin‐coated as the active layer and is sandwiched between an aluminum electrode and an indium‐tin‐oxide (ITO) electrode. This device shows very good memory performance, with an ON/OFF current ratio of more than 105 and a low misreading rate through the precise control of the ON and OFF states. The stability of the nanoaggregated PVDR device is much higher than that of the non‐nanoaggregated PVDR device. This difference in device stability under constant voltage stress can be mainly attributed to the difference in the film crystallinity and surface morphology. No degradation in current density was observed for the ON‐ and OFF‐states after more than one hundred million (108) continuous read cycles indicating that both states were insensitive to the read cycles. These results render the nanoaggregated PVDR polymer as promising components for high‐performance polymer memory devices.  相似文献   

9.
We demonstrate a novel lithographic technique utilizing a solvent to fabricate a chemically based semiconductor microdevice from an aqueous solution. According to this technique, SnO2 thin film could be integrated onto predefined sites on a SiO2/Si wafer. A patterned octadecyltrimethoxysilane self‐assembled monolayer (ODS‐SAM) was prepared by vacuum ultraviolet (VUV) irradiation through a photomask to use as a template for the fabrication of a micropatterned SnO2 thin film on the SiO2/Si surface. A Sn‐based thin film was then deposited onto the entire surface of the ODS template from an aqueous solution containing 0.03 mol L–1 of SnCl2·2H2O at 60 °C for 16 h in an ambient atmosphere. The thin film deposited on the methyl‐terminated area of the template was then peeled using an ultrasonic rinse in anhydrous toluene for 30 min, while the film deposited on the silanol area remained intact and undamaged. Rinsing in hydrophilic solvents did not facilitate peeling of the thin film from the methyl‐terminated area. We succeeded by this process in obtaining a high‐resolution, micropatterned Sn‐based thin film on an ODS‐SAM template on Si. The as‐deposited film was composed of fine Sn‐based particles. The sensitivity of this SnO2 thin film to H2 gas increases linearly with improving crystallinity. The effectiveness of anhydrous toluene as a rinse in solution lithography is discussed from the viewpoint of the high hydrophobic affinity between the rinse solvent and the terminal groups in the monolayer template.  相似文献   

10.
A novel phosphorus‐containing porous polymer is efficiently prepared from tris(4‐vinylphenyl)phosphane by radical polymerization, and it can be easily ionized to form an ionic porous polymer after treatment with hydrogen iodide. Upon ionic exchange, transition‐metal‐containing anions, such as tetrathiomolybdate (MoS4 2?) and hexacyanoferrate (Fe(CN)6 3?), are successfully loaded into the framework of the porous polymer to replace the original iodide anions, resulting in a polymer framework containing complex anions (termed HT‐Met, where Met = Mo or Fe). After pyrolysis under a hydrogen atmosphere, the HT‐Met materials are efficiently converted at a large scale to metal‐phosphide‐containing porous carbons (denoted as MetP@PC, where again Met = Mo or Fe). This approach provides a convenient pathway to the controlled preparation of metal‐phosphide‐loaded porous carbon composites. The MetP@PC composites exhibit superior electrocatalytic activity for the hydrogen evolution reaction (HER) under acidic conditions. In particular, MoP@PC with a low loading of 0.24 mg cm?2 (on a glass carbon electrode) affords an iR‐corrected (where i is current and R is resistance) current density of up to 10 mA cm?2 at 51 mV versus the reversible hydrogen electrode and a very low Tafel slope of 45 mV dec?1, in rotating disk measurements under saturated N2 conditions.  相似文献   

11.
A novel approach for fabrication of 3D cellular structures using new thermosensitive shape‐changing polymer films with photolithographically patterned surface—4D biofabrication is reported. The surface of shape‐changing polymer films is patterned to selectively adsorb cells in specific regions. The 2D cell pattern is converted to the 3D cell structure after temperature‐induced folding of the polymer films. This approach has a great potential in the field of tissue engineering and bioscaffolds fabrication.  相似文献   

12.
The influence of the interface of the dielectric SiO2 on the performance of bottom‐contact, bottom‐gate poly(3‐alkylthiophene) (P3AT) field‐effect transistors (FETs) is investigated. In particular, the operation of transistors where the active polythiophene layer is directly spin‐coated from chlorobenzene (CB) onto the bare SiO2 dielectric is compared to those where the active layer is first spin‐coated then laminated via a wet transfer process such that the film/air interface of this film contacts the SiO2 surface. While an apparent alkyl side‐chain length dependent mobility is observed for films directly spin‐coated onto the SiO2 dielectric (with mobilities of ≈10?3 cm2 V?1 s?1 or less) for laminated films mobilities of 0.14 ± 0.03 cm2 V?1 s?1 independent of alkyl chain length are recorded. Surface‐sensitive near edge X‐ray absorption fine structure (NEXAFS) spectroscopy measurements indicate a strong out‐of‐plane orientation of the polymer backbone at the original air/film interface while much lower average tilt angles of the polymer backbone are observed at the SiO2/film interface. A comparison with NEXAFS on crystalline P3AT nanofibers, as well as molecular mechanics and electronic structure calculations on ideal P3AT crystals suggest a close to crystalline polymer organization at the P3AT/air interface of films from CB. These results emphasize the negative influence of wrongly oriented polymer on charge carrier mobility and highlight the potential of the polymer/air interface in achieving excellent “out‐of‐plane” orientation and high FET mobilities.  相似文献   

13.
Polymer ferroelectric‐gate field effect transistors (Fe‐FETs) employing ferroelectric polymer thin films as gate insulators are highly attractive as a next‐generation non‐volatile memory. Furthermore, polymer Fe‐FETs have been recently of interest owing to their capability of storing data in more than 2 states in a single device, that is, they have multi‐level cell (MLC) operation potential for high density data storage. However, among a variety of technological issues of MLC polymer Fe‐FETs, the requirement of high voltage for cell operation is one of the most urgent problems. Here, a low voltage operating MLC polymer Fe‐FET memory with a high dielectric constant (k) ferroelectric polymer insulator is presented. Effective enhancement of capacitance of the ferroelectric gate insulator layer is achieved by a simple binary solution‐blend of a ferroelectric poly(vinylidene fluoride‐co‐trifluoroethylene) (PVDF‐TrFE) (k ≈ 8) with a relaxer high‐k poly(vinylidene‐fluoride–trifluoroethylene–chlorotrifluoroethylene) (PVDF‐TrFE‐CTFE) (k ≈ 18). At optimized conditions, a ferroelectric insulator with a PVDF‐TrFE/PVDF‐TrFE‐CTFE (10/5) blend composition enables the discrete six‐level multi‐state operation of a MLC Fe‐FET at a gate voltage sweep of ±18 V with excellent data retention and endurance of each state of more than 104 s and 120 cycles, respectively.  相似文献   

14.
We report photovoltaic devices consisting of patterned TiO2, porphyrin dyes, and layer‐by‐layer (LBL) polyelectrolyte multilayer/oligoethylene glycol dicarboxylic acid (OEGDA) composite films. A composite polyelectrolyte LBL/OEGDA film was fabricated by formation of an alternating multilayer of linear polyethyleneimine (LPEI) and polyacrylic acid (PAA), followed by immersion of the LBL film into an OEGDA aqueous solution. The ionic conductivity attained in this LBL LPEI/PAA and OEGDA composite film was approximately 10–5 S cm–1 at room temperature and humidity. Investigations of dye‐sensitized photovoltaic devices constructed with the LBL (LPEI/PAA)/OEGDA composite films, TiO2, and four types of porphyrin dyes resulted in optimization of the dye molecule and its orientation at the interface with the ionically conductive composite. The photocurrent value of photovoltaic devices constructed with the composite LBL/OEGDA film from illumination of a xenon white light source exhibited a nearly 1.5 times enhancement over the device without OEGDA. This enhancement of the photocurrent was due to the high room‐temperature ionic conductivity of the multilayer composite film. Further marked improvements of the photovoltaic performance were achieved by patterning the TiO2 electrode using polymer stamping as a template for TiO2 deposition. The device with patterned TiO2 electrodes exhibited almost 10 times larger conversion efficiencies than a similar device without patterning.  相似文献   

15.
Micro‐ and nanostructuring of conjugated polymers are of critical importance in the fabrication of molecular electronic devices as well as photonic and bandgap materials. The present report delineates the single‐step self‐organization of highly ordered structures of functionalized poly(p‐phenylene)s without the aid of either a controlled environment or expensive fabrication methodologies. Microporous films of these polymers, with a honeycomb pattern, were prepared by direct spreading of the dilute polymer solution on various substrates, such as glass, quartz, silicon wafer, indium tin oxide, gold‐coated mica, and water, under ambient conditions. The polymeric film obtained from C12PPPOH comprises highly periodic, defect‐free structures with blue‐light‐emitting properties. It is expected that such microstructured, conjugated polymeric films will have interesting applications in photonic and optoelectronic devices. The ability of the polymer to template the facile micropatterning of nanomaterials gives rise to hybrid films with very good spatial dispersion of the carbon nanotubes.  相似文献   

16.
The understanding of the lateral morphology stability of thin polymer devices is of fundamental importance. In this work, the lateral morphology in a model system consisting of thin polymer films capped with thin metal layers on a Si substrate is investigated. When the model system is heated above a critical temperature, a characteristic surface topographic structure is observed that has a well‐defined periodicity but random orientation. It is shown that the minimum temperature, Tmin, required for the surface pattern to be observed decreases with increasing polymer‐film thickness. Increasing either the metal‐ or polymer‐layer thickness increases the characteristic wavelength of the topography. It is believed that the dominating driving force for the surface corrugated‐pattern formation is the thermal‐expansion‐coefficient mismatch of the capping layer and the substrate. A theoretical model based on local bending of a thin, stiff surface film on a thin, elastic medium is used to provide a quantitative analysis of the surface morphology. The calculated minimum temperature required for the surface morphology and the periodicity of the surface patterns to form are in strong agreement with the experimental results. By contrast, systems with prefabricated topographic patterns within any of the three layers (polymer, metal, substrate) produce highly anisotropic surface topographies aligned perpendicular to the prefabricated topographic structure. It is also found that, in a model system with pre‐patterned polymer films, a much higher critical temperature is required for the surface morphology to be observed. The changes in apparent stability and morphological orientation in the pre‐patterned systems can be understood as a result of the anisotropic release of the lateral surface stress during the heat treatment.  相似文献   

17.
Substrates with high transmittance and high haze are desired for increasing the light outcoupling efficiency of organic light‐emitting diodes (OLEDs). However, most of the polymer films used as substrate have high transmittance and low haze. Herein, a facile route to fabricate a built‐in haze glass‐fabric reinforced siloxane hybrid (GFRH) film having high total transmittance (≈89%) and high haze (≈89%) is reported using the scattering effect induced by refractive index contrast between the glass fabric and the siloxane hybrid (hybrimer). The hybrimer exhibiting large refractive index contrast with the glass fabric is synthesized by removing the phenyl substituents. Besides its optical properties, the hazy GFRH films exhibit smooth surface (Rsq = 0.2 nm), low thermal expansion (13 ppm °C−1), high chemical stability, and dimensional stability. Owing to the outstanding properties of the GFRH film, OLED is successfully fabricated onto the film exhibiting 74% external quantum efficiency enhancement. The hazy GFRH's unique optical properties, excellent thermal stability, outstanding dimensional stability, and the ability to perform as a transparent electrode enable them as a wide ranging substrate for the flexible optoelectronic devices.  相似文献   

18.
Robust coatable polarizer is fabricated by the self‐assembly of lyotropic chromonic liquid crystals and subsequent photo‐polymerizing processes. Their molecular packing structures and optical behaviors are investigated by the combined techniques of microscopy, scattering and spectroscopy. To stabilize the oriented Sunset Yellow FCF (H‐SY) films and to minimize the possible defects generated during and after the coating, acrylic acid (AA) is added to the H‐SY/H2O solution and photo‐polymerized. Utilizing cross‐polarized optical microscopy, phase behaviors of the H‐SY/H2O/AA solution are monitored by varying the compositions and temperatures of the solution. Based on the experimental results of two‐dimensional wide angle X‐ray diffraction and selected area electron diffraction, the H‐SY crystalline unit cell is determined to be a monoclinic structure with the dimensions of a = 1.70 nm, b = 1.78 nm, c = 0.68 nm, α = β = 90.0° and γ = 84.5°. The molecular arrangements in the oriented H‐SY films were further confirmed by polarized Fourier‐transform infrared spectroscopy. The polymer‐stabilized H‐SY films show good mechanical and chemical stabilities with a high polarizability. Additionally, patterned polarizers are fabricated by applying a photo‐mask during the photo‐polymerization of AA, which may open new doors for practical applications in electro‐optic devices.  相似文献   

19.
Highly conductive poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films as stand‐alone electrodes for organic solar cells have been optimized using a solvent post‐treatment method. The treated PEDOT:PSS films show enhanced conductivities up to 1418 S cm?1, accompanied by structural and chemical changes. The effect of the solvent treatment on PEDOT:PSS has been investigated in detail and is shown to cause a reduction of insulating PSS in the conductive polymer layer. Using these optimized electrodes, ITO‐free, small molecule organic solar cells with a zinc phthalocyanine (ZnPc):fullerene C60 bulk heterojunction have been produced on glass and PET substrates. The system was further improved by pre‐heating the PEDOT:PSS electrodes, which enhanced the power conversion efficiency to the values obtained for solar cells on ITO electrodes. The results show that optimized PEDOT:PSS with solvent and thermal post‐treatment can be a very promising electrode material for highly efficient flexible ITO‐free organic solar cells.  相似文献   

20.
Low‐power, nonvolatile memory is an essential electronic component to store and process the unprecedented data flood arising from the oncoming Internet of Things era. Molybdenum disulfide (MoS2) is a 2D material that is increasingly regarded as a promising semiconductor material in electronic device applications because of its unique physical characteristics. However, dielectric formation of an ultrathin low‐k tunneling on the dangling bond‐free surface of MoS2 is a challenging task. Here, MoS2‐based low‐power nonvolatile charge storage memory devices are reported with a poly(1,3,5‐trimethyl‐1,3,5‐trivinyl cyclotrisiloxane) (pV3D3) tunneling dielectric layer formed via a solvent‐free initiated chemical vapor deposition (iCVD) process. The surface‐growing polymerization and low‐temperature nature of the iCVD process enable the conformal growing of low‐k (≈2.2) pV3D3 insulating films on MoS2. The fabricated memory devices exhibit a tunable memory window with high on/off ratio (≈106), excellent retention times of 105 s with an extrapolated time of possibly years, and an excellent cycling endurance of more than 103 cycles, which are much higher than those reported previously for MoS2‐based memory devices. By leveraging the inherent flexibility of both MoS2 and polymer dielectric films, this research presents an important milestone in the development of low‐power flexible nonvolatile memory devices.  相似文献   

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