首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
While many high‐performance polymer semiconductors are reported for organic field‐effect transistors (OFETs), most require a high‐temperature postdeposition annealing of channel semiconductors to achieve high performance. This negates the fundamental attribute of OFETs being a low‐cost alternative to conventional high‐cost silicon technologies. A facile solution process is developed through which high‐performance OFETs can be fabricated without thermal annealing. The process involves incorporation of an incompatible hydrocarbon binder or wax into the channel semiconductor composition to drive rapid phase separation and instantaneous crystallization of polymer semiconductor at room temperature. The resulting composite channel semiconductor film manifests a nano/microporous surface morphology with a continuous semiconductor nanowire network. OFET mobility of up to about 5 cm2 V?1 s?1 and on/off ratio ≥ 106 are attained. These are hitherto benchmark performance characteristics for room‐temperature, solution‐processed polymer OFETs, which are functionally useful for many impactful applications.  相似文献   

2.
Using differential scanning calorimetry (DSC) measurements in combination with structural and optical characterization we have investigated the formation conditions of different phases of tris(8‐hydroxyquinoline)aluminum (Alq3). We have identified the δ‐phase as a high‐temperature phase of Alq3 being composed of the facial stereoisomer, and report an efficient method to obtain blue luminescent Alq3 by a simple annealing process. This allows the preparation of large amounts of pure δ‐Alq3 by choosing appropriate annealing conditions, which is necessary for further characterization of this blue‐luminescent phase, and offers the possibility of fabricating blue organic light‐emitting devices (OLEDs) from this material.  相似文献   

3.
Tuning the side chains of conjugated polymers is a simple, yet effective strategy for modulating their structural and electrical properties, but their impact on n‐type conjugated polymers has not been studied extensively, particularly in the area of all‐polymer solar cells (all‐PSCs). Herein, the effects of side chain engineering of P(NDI2OD‐T2) polymer (also known as Polyera Activink N2200) are investigated, which is the most widely used n‐type polymer in all‐PSCs and organic field‐effect transistors (OFETs), on their structural and electronic properties. A series of naphthalenediimide‐bithiophene‐based copolymers (P(NDIR‐T2)) is synthesized, with different side chains (R) of 2‐hexyldecyl (2‐HD), 2‐octyldodecyl (2‐OD), and 2‐decyltetradecyl (2‐DT). The P(NDI2HD‐T2) exhibits more noticeable crystalline behaviors than P(NDI2OD‐T2) and P(NDI2DT‐T2), thereby facilitating superior 3D charge transport. For example, the P(NDI2HD‐T2) shows the highest OFET electron mobility (1.90 cm2 V?1 s?1). Also, a series of all‐PSCs is produced using different electron donors of PTB7‐Th, PTB7, and PPDT2FBT. The P(NDI2HD‐T2) based all‐PSCs produce much higher power conversion efficiency (PCE) irrespective of the electron donors. In particular, the PTB7‐Th:P(NDI2HD‐T2) forms highly ordered, strong face‐on interchain stackings, and has better intermixed bulk‐heterojunction morphology, producing the highest PCE of 6.11% that has been obtained by P(NDIR‐T2) based all‐PSCs to date.  相似文献   

4.
A novel cell isolation and release platform using electrospun polystyrene‐poly(styrene‐co‐maleic anhydride) (PS‐PSMA) nanofibers is presented. Ethanol treatment of PS‐PSMA nanofibers, employed for the purpose of sterilization, significantly increases their inter‐fiber space for both antibody conjugation and subsequent cell separation. For the selective isolation of CD4+ T cells from heterogeneous mixtures of mouse lymph nodes, capture efficiencies of up to 100% are achieved while maintaining cellular integrity and viability. Once captured, CD4+ T lymphocytes can also be released from the NF scaffolds, further demonstrating its potential functionality as an immune cell‐supporting and releasing matrix. This is the first demonstration of lymphocyte‐culture scaffolds enabling selective isolation, accommodation, and sustained release of CD4+ T cells for the purpose of cell therapies.  相似文献   

5.
Two novel perylene diimide (PDI)–based derivatives, Alq3‐PDI and Alq3‐PDI 2, are synthesized by flanking a 3D tri(8‐hydroxyquinoline)aluminum(III) (Alq3) core with PDI and a helical PDI dimer (PDI2) to construct high‐performance small molecular nonfullerene acceptors (SMAs). The 3D Alq3 core significantly suppresses the molecular aggregation of the resulting SMAs, leading to a well‐mixed blend with a PTTEA donor polymer and weak phase separation. Compared with Alq3‐PDI , the extended π‐conjugation of Alq3‐PDI2 results in higher‐order molecular packing, which improves the absorption and phase separation behavior. Thus, the Alq3‐PDI2 devices have higher Jsc and FF values and better device performance, which are further enhanced by a small amount of 4,4′‐bipyridine (Bipy) as an additive. The coordination between Bipy and the Alq3 core promotes molecular packing and phase separation, which lower charge recombination and enhanced charge collection in the resulting devices. Therefore, a largely improved Jsc of 15.74 mA cm?2 and very high FF of 71.27% are obtained in the Alq3‐PDI2 devices, resulting in a power conversion efficiency of 9.54%, which is the best value reported for PDI‐based polymer solar cells. The coordination can also serve as a “molecular lock,” which prevents molecular motion and thus improves device stability.  相似文献   

6.
A biosensor array is fabricated using an interpenetrating polymer network consisting of photonic film templated from reactive cholesteric liquid crystal (CLC) and enzyme‐immobilized polyacrylic acid (PAA). The solid‐state photonic film on the glass substrate is successfully templated by ultraviolet (UV) curing of the reactive CLC mixture of a reactive mesogen mixture of RMM 727 (from Merck) and a nonreactive chiral dopant of (S)‐4‐cyano‐4′‐(2‐methylbutyl)biphenyl following the extraction of the chiral dopant. The acrylic acid monomer mixed with a cross‐linker of tri(propylene glycol) diacrylate is infiltrated into the extracted space of the photonic film, and UV‐cured with a photomask to obtain a patterned array‐dot film. The interpenetrated cholesteric liquid crystal/hydrogel polymer network (CLC‐hydrogel‐IPN) array is further functionalized in the individual dots with urease, for a model study of biosensor array applications. The dots of the CLC‐hydrogel‐IPN array respond independently to the urea by a color change with high sensitivity and stability. Thus, the patterned CLC‐hydrogel‐IPN can be used as a new biosensor array for cost‐effective and easy visual detection without any sophisticated instruments.  相似文献   

7.
A new series of charge neutral Os(II) pyridyl azolate complexes with either bis(diphenylphosphino)methane (dppm) or cis‐1,2‐bis(diphenylphosphino)ethene (dppee) chelates were synthesized, and their structural, electrochemical, photophysical properties and thermodynamic relationship were established. For the dppm derivatives 3a and 4a , the pyridyl azolate chromophores adopt an eclipse orientation with both azolate segments aligned trans to each other, and with the pyridyl groups resided the sites that are opposite to the phosphorus atoms. In sharp contrast, the reactions with dppee ligand gave rise to the formation of two structural isomers for all three kind of azole chromophores, with both azolate or neutral heterocycles (i.e., pyridyl or isoquinolinyl fragments) located at the mutual trans‐disposition around the Os metal (denoted as series of a and b complexes). These chelating phosphines Os(II) complexes show remarkably high thermal stability, among which and several exhibit nearly unitary phosphorescence yield in deaerated solution at RT. A polymer light‐emitting device (PLED) prepared using 0.4 mol % of 5a as dopant in a blend of poly(vinylcarbazole) (PVK) and 30 wt % of 2‐tert‐butylphenyl‐5‐biphenyl‐1,3,4‐oxadiazole (PBD) exhibits yellow emission with brightness of 7208 cd m–2, an external quantum efficiency of 10.4 % and luminous efficiency of 36.1 cd A–1 at current density of 20 mA cm–2. Upon changing to 1.6 mol % of 6a , the result showed even better brightness of 9212 cd m–2, external quantum efficiency of 12.5 % and luminous efficiency of 46.1 cd A–1 at 20 mA cm–2, while the max. external quantum efficiency of both devices reaches as high as 11.7 % and 13.3 %, respectively. The high PL quantum efficiency, non‐ionic nature, and short radiative lifetime are believed to be the determining factors for this unprecedented achievement.  相似文献   

8.
We report on a low‐threshold three‐dimensional (3D) void generation inside a polyvinyl‐alcohol (PVA) polymer matrix doped with gold nanorods (NRs) by near infra red femtosecond laser pulses. By matching the laser wavelength to the surface plasmon resonance band of the embedded gold NRs, the void generation threshold could be reduced by one order of magnitude lower than undoped matrix. We discuss physical mechanisms involved in the void generation, where distinction between the decomposition of gold NR or PVA is drawn in single pulse and multiple pulse irradiations. We also demonstrate 3D void recording for applications in 3D optical data storage.  相似文献   

9.
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   

10.
Aqueous zinc‐ion batteries are receiving increasing attention; however, the development of high‐voltage cathodes is limited by the narrow voltage window of conventional aqueous electrolytes. Herein, it is reported that Na3V2(PO4)2O1.6F1.4 exhibits the excellent performance, optimal to date, among polyanion cathode materials in a novel neutral water‐in‐bisalts electrolyte of 25 m ZnCl2 + 5 m NH4Cl. It delivers a reversible capacity of 155 mAh g?1 at 50 mA g?1, a high average operating potential of ≈1.46 V, and stable cyclability of 7000 cycles at 2 A g?1.  相似文献   

11.
A rapid fabrication method of highly reflective TiO2 inverse opal (IO) film exhibiting controllable thickness, high TiO2 content, and excellent interfacial contact with glass substrate is presented. By inducing accelerated solvent evaporation during the colloidal self‐assembly process, a composite film of polystyrene (PS)/TiO2 has been directly fabricated on a fluorine doped tin oxide (FTO) glass substrate, which exhibits the highly ordered opaline structure of PS embedded into the TiO2 matrix. This hybrid fabrication path leads to the formation of layers with the preferred {111} face‐centered cubic (FCC) orientation parallel to the substrate and to produce a 1 cm2‐wide well‐ordered composite colloidal crystal film in less than 30 min. The film showed highly ordered FCC structure, particularly at the upper region, due to the induced solvent evaporation and exhibited a reliable light modulation at a reflectance mode. Regardless of the size of sacrificial PS microspheres, TiO2 IO films of controllable thickness were successfully formed by varying the moving speed of the fabrication cell. The binary aqueous dispersion of tailor‐made anatase TiO2 nanoparticles and monodisperse PS microspheres showed a high degree of dispersion stability under basic conditions. Hydrothermal treatment of the TiO2 dispersion favored the crystallinity of the coated film and provided small volume contraction after thermal calcinations. The high degree of dispersion stability enabled to increase TiO2 content in a binary mixture, which is more favorable toward the robust and large‐area IO film. The calcined films exhibited excellent mechanical robustness and intimate interfacial contact with the glass substrate. which in turn resulted in higher TiO2 content near the glass substrate. The TiO2 IO film was tested as a dye‐sensitized solar cell (DSSC) photoelectrode, and a single cell showed a relatively high photon‐to‐current conversion efficiency of 4.2%. The high TiO2 content of IO film and its good adhesion to the FTO subratrate remarkably improved in the performance of the solar cell compared to the previous investigations where post‐infiltration of TiO2 had been employed.  相似文献   

12.
Simple, low‐cost and yet accurate, sensitive, and quantitative detection of a broad range of analytical targets by means of small footprint sensing devices has the potential to revolutionize medical diagnostics, food safety, and environmental monitoring. This work demonstrates a functional nucleic acids (FNAs) tethered AuNPs/β‐Ni(OH)2 nanosheets (NS)/Ni foam nanocomposite as a miniaturized electrode. Through the rational design of a low‐barrier ohmic contact of AuNPs to β‐Ni(OH)2 NS and a target mediated nanochannel electron transfer effect, a variety of analytical targets, ranging from a disease marker (thrombin, 16.3 × 10?12 m detection limit) to an important biological cofactor (adenosine, 3.2 × 10?12 m detection limit), and to a toxic metal ion (Hg2+, 3.1 × 10?12 m detection limit), are detected with ultrasensitivity. The presence of target triggers the conformational change of FNAs, introducing strong steric hindrance and electrostatic repulsion to the diffusion of electron indicators toward the electrode surface, ultimately leading to the changes in impedance. A novel equivalent circuit considering the capacitive reactance is proposed to describe the 2D NS‐based impedance DNA bioelectrode. This sensing platform is easily applicable to the detection of many other targets in diverse sample matrices through the use of other suitable FNAs materials.  相似文献   

13.
Metal‐organic frameworks possess tremendous potential in biomedical areas for their particular structure. In this study, the authors explored Fe2+‐adsorbed nanoscaled zeolitic imidazolate framework‐8 (ZIF‐8) for in vivo multimodal imaging of cancerous cells for early diagnosis of target cancers. The observations demonstrate that adding Fe2+ into the suspension of ZIF‐8 can neutralize the alkalinity and lower toxicity, while the Fe2+‐adsorbed ZIF‐8 can readily transform to fluorescence ZnO and super paramagnetic Fe3O4 under the synergistic reaction of ROS, GSH, and acids. It is evident that the formation of the nanoclusters ZnO and Fe3O4 only occurred in cancerous cells and does not take place in normal cells, which can be attributed to the different ROS levels and specific micro‐environment in tumor and normal cells. This raises the possibility for the Fe2+‐adsorbed zeolitic imidazolate frameworks to act as promising agents for the in vivo multimodal imaging of cancers in their early stage.  相似文献   

14.
Bulk 1T‐TaSe2 as a charge‐density‐wave (CDW) conductor is of special interest for CDW‐based nanodevice applications because of its high CDW transition temperature. Reduced dimensionality of the strongly correlated material is expected to result in significantly different collective properties. However, the growth of atomically thin 1T‐TaSe2 crystals remains elusive, thus hampering studies of dimensionality effects on the CDW of the material. Herein, chemical vapor deposition (CVD) of atomically thin TaSe2 crystals is reported with controlled 1T phase. Scanning transmission electron microscopy suggests the high crystallinity and the formation of CDW superlattice in the ultrathin 1T‐TaSe2 crystals. The commensurate–incommensurate CDW transition temperature of the grown 1T‐TaSe2 increases with decreasing film thickness and reaches a value of 570 K in a 3 nm thick layer, which is 97 K higher than that of previously reported bulk 1T‐TaSe2. This work enables the exploration of collective phenomena of 1T‐TaSe2 in the 2D limit, as well as offers the possibility of utilizing the high‐temperature CDW films in ultrathin phase‐change devices.  相似文献   

15.
16.
The branching point of the side‐chain of naphthalenediimide (NDI)‐based conjugated polymers is systematically controlled by incorporating four different side‐chains, i.e., 2‐hexyloctyl (P(NDI1‐T)), 3‐hexylnonyl (P(NDI2‐T)), 4‐hexyldecyl (P(NDI3‐T)), and 5‐hexylundecyl (P(NDI4‐T)). When the branching point is located farther away from the conjugated backbones, steric hindrance around the backbone is relaxed and the intermolecular interactions between the polymer chains become stronger, which promotes the formation of crystalline structures in thin film state. In particular, thermally annealed films of P(NDI3‐T) and P(NDI4‐T), which have branching points far away from the backbone, possess more‐developed bimodal structure along both the face‐on and edge‐on orientations. Consequently, the field‐effect electron mobilities of P(NDIm‐T) polymers are monotonically increased from 0.03 cm2 V−1 s−1 in P(NDI1‐T) to 0.22 cm2 V−1 s−1 in P(NDI4‐T), accompanied by reduced activation energy and contact resistance of the thin films. In addition, when the series of P(NDIm‐T) polymers is applied in all‐polymer solar cells (all‐PSCs) as electron acceptor, remarkably high‐power conversion efficiency of 7.1% is achieved along with enhanced current density in P(NDI3‐T)‐based all‐PSCs, which is mainly attributed to red‐shifted light absorption and enhanced electron‐transporting ability.  相似文献   

17.
The p‐type semiconducting copper oxides (CuO and Cu2O) are promising materials for gas sensors, owing to their characteristic oxygen adsorption properties and low operation temperature. In this study, the sensing performance of a CuO‐based chemiresistor is significantly enhanced by incorporating Ag nanoparticles on high‐resolution p‐type CuO/Cu2O nanopattern channels. The high‐resolution CuO/Cu2O/Ag nanochannel is fabricated using a unique top‐down nanolithographic approach. The gas response (ΔR/Ra) of the CuO/Cu2O/Ag gas sensor increases by a maximum factor of 7.3 for various volatile organic compounds compared with a pristine CuO/Cu2O gas sensor. The sensors exhibit remarkable sensitivity (ΔR/Ra = 8.04) at 125 parts per billion (ppb) for acetone analytes. As far as it is known, this is the highest sensitivity achieved for p‐type metal oxide semiconductor (MOS)‐based gas sensors compared to previous studies. Furthermore, the outstanding gas responses observed in this study are superior to the most of n‐type MOS‐based gas sensors. The high sensitivity of the sensor is attributed to i) the high resolution (≈30 nm), high aspect ratio (≈12), and ultrasmall grain boundaries (≈10 nm) of the CuO/Cu2O nanopatterns and ii) the electronic sensitization and chemical sensitization effects induced by incorporating Ag nanoparticles on the CuO/Cu2O channels.  相似文献   

18.
This paper proposes a 10‐µm thick oxide layer structure that can be used as a substrate for RF circuits. The structure has been fabricated using an anodic reaction and complex oxidation, which is a combined process of low‐temperature thermal oxidation (500 °C, for 1 hr at H2O/O2) and a rapid thermal oxidation (RTO) process (1050 °C, for 1 min). The electrical characteristics of the oxidized porous silicon layer (OPSL) were almost the same as those of standard thermal silicon dioxide. The leakage current density through the OPSL of 10 µm was about 10 to 50 nA/cm2 in the range of 0 to 50 V. The average value of the breakdown field was about 3.9 MV/cm. From the X‐ray photo‐electron spectroscopy (XPS) analysis, surface and internal oxide films of OPSL prepared by a complex process were confirmed to be completely oxidized. The role of the RTO process was also important for the densification of the porous silicon layer (PSL) oxidized at a lower temperature. The measured working frequency of the coplanar waveguide (CPW) type short stub on an OPSL prepared by the complex oxidation process was 27.5 GHz, and the return loss was 4.2 dB, similar to that of the CPW‐type short stub on an OPSL prepared at a temperature of 1050 °C (1 hr at H2O/O2). Also, the measured working frequency of the CPW‐type open stub on an OPSL prepared by the complex oxidation process was 30.5 GHz, and the return was 15 dB at midband, similar to that of the CPW‐type open stub on an OPSL prepared at a temperature of 1050 °C (1 hr at H2O/O2).  相似文献   

19.
In this work, a full‐cell sodium‐ion battery (SIB) with a high specific energy approaching 300 Wh kg?1 is realized using a sodium vanadium fluorophosphate (Na3V2(PO4)2F3, NVPF) cathode and a tin phosphide (SnPx) anode, despite both electrode materials having greatly unbalanced specific capacities. The use of a cathode employing an areal loading more than eight times larger than that of the anode can be achieved by designing a nanostructured nanosized NVPF (n‐NVPF) cathode with well‐defined particle size, porosity, and conductivity. Furthermore, the high rate capability and high potential window of the full‐cell can be obtained by tuning the Sn/P ratio (4/3, 1/1, and 1/2) and the nanostructure of an SnPx/carbon composite anode. As a result, the full‐cell SIBs employing the nanostructured n‐NVPF cathode and the SnPx/carbon composite anode (Sn/P = 1/1) exhibit outstanding specific energy (≈280 Wh kg?1(cathode+anode)) and energy efficiency (≈78%); furthermore, the results are comparable to those of state‐of‐the‐art lithium‐ion batteries.  相似文献   

20.
Imaging early molecular changes in osteoarthritic (OA) joints is instrumental for the development of disease‐modifying drugs. To this end, a fluorescent resonance energy transfer‐based peptide probe that is cleavable by matrix metalloproteinase 13 (MMP‐13) has been developed. This protease degrades type II collagen, a major matrix component of cartilage. The probe exhibits high catalytic efficiency (kcat/KM = 6.5 × 105m ?1 s?1) and high selectivity for MMP‐13 over a set of nine MMPs. To achieve optimal in vivo pharmacokinetics and tissue penetration, the probe has been further conjugated to a linear l ‐polyglutamate chain of 30 kDa. The conjugate detects early biochemical events that occur in a surgically induced murine model of OA before major histological changes. The nanometric probe is suitable for the monitoring of in vivo efficacy of an orally bioavailable MMP‐13 inhibitor, which effectively blocks cartilage degradation during the development of OA. This new polymer‐probe can therefore be a useful tool in detecting early OA, disease progression, and in developing MMP‐13‐based disease‐modifying drugs for OA.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号