This contribution presents a kind of novel and neutral network films based on EDOT formed by in situ electrocopolymerization (ECP). The ECP films which are neutral and colorless exhibit the conductivity of 0.2–0.5 S · cm−1, WF of 4.79–5.20 eV, and RMS roughness of 3.51–5.26 nm. The electroluminescent devices where ECP films acted as hole‐transport layer (HTL) exhibit higher brightness, current density, efficiency (20–30% improvement), and stability than that of PEDOT:PSS HTL device. The ECP films also significantly benefit the stability of neighboring organic layer compared to PEDOT:PSS. This kind of new ECP films affords more opportunities to develop organic light‐emitting diodes (OLEDs) with high performances and stability.
Summary: Due to its capability of dispensing very small volumes of different liquids in a controlled manner, ink‐jet printing is well suited for combinatorial experiments. The multi‐nozzle ink‐jet delivery system is especially advantageous for parallel chemical synthesis of different materials. We have used ink‐jet printing of an oxidizing agent to pattern a pre‐coated conducting polymer, poly(3,4‐ethylenedioxy)‐thiophene‐poly(styrene sulfonate) (PEDOT‐PSS), yielding electrodes with predefined shapes and a controlled degree of sheet resistivity for use in gray‐scale organic light‐emitting devices (OLEDs). The electrical and optical properties of the PEDOT‐PSS layer are modified via chemical interaction using the oxidizing agent. These experiments were performed using a desktop ink‐jet printer in conjunction with common graphic software which employed color functions such as CMY (cyan, magenta and yellow), HSL (hue, saturation and luminosity) and RGB (red, green and blue).
Photographs of gray‐scale OLEDs patterned on PEDOT‐PSS surfaces by an ink‐jet printer on plastic substrates. 相似文献
We report that poly(3,4‐ethylenedioxythiophene) derived from poly(ionic liquid) (PEDOT:PIL) constitutes a unique polymeric hole‐injecting material capable of improving device lifetime in organic light‐emitting diodes (OLEDs). Imidazolium‐based poly(ionic liquid)s were engineered to impart non‐acidic and non‐aqueous properties to PEDOT without compromising any other properties of PEDOT. A fluorescent OLED was fabricated using PEDOT:PIL as a hole‐injection layer and subjected to a performance evaluation test. In comparison with a control device using a conventional PEDOT‐based material, the device with PEDOT:PIL was found to achieve a significant improvement in terms of device lifetime. This improvement was attributed to a lower indium content in the PEDOT:PIL layer, which can be also interpreted as the effective protection characteristics of PEDOT:PIL for indium extraction from the electrodes.
Conducting microfibers of poly(3,4‐ethylenedioxythiophene) doped with poly(4‐styrene sulfonate), having a diameter ranging between 4.6 and 16 μm, were fabricated by a wet‐spinning technique. The as‐spun microfiber had no notable orientation of polymer chains with poor crystallinity, and electrical conductivity was in the order of 10−1 S · cm−1 regardless of the diameter. Young's modulus, tensile strength, and elongation at break for the resulting microfiber were 1.1 ± 0.3 GPa, 17.2 ± 5.1 MPa, and 4.3 ± 2.3%, respectively.
SEM image of a PEDOT/PSS microfiber reported here. 相似文献
Summary: Polypyrrole (PPy), polyaniline (PANI), and poly(ethylenedioxythiophene) (PEDOT) aqueous dispersions were prepared by polymerizing the corresponding monomer in the presence of a polymeric ionic liquid (PIL), poly(1‐vinyl‐3‐ethylimidazolium bromide). By addition of bispentafluoroethanesulfonimide lithium salt, the PIL stabilizer becomes hydrophobic and precipitates in water and traps the conducting polymer microparticles inside. The dispersion of the recovered powders in organic solvents leads to organic conducting dispersions. After casting the organic dispersions, hydrophobic films with electrical conductivity values as high as 0.1 S · cm−1 were obtained.
A new synthetic route to new organic dispersions. 相似文献
Summary: Novel hyperbranched poly(amine‐ester) (HPAE) cross‐linked films were prepared by cross‐linking the terminal hydroxyl groups of HPAE using glutaraldehyde (GA). Atom force microscope and scanning electron microscope revealed their smooth surfaces, dense and homogenous matrices. Property characterizations indicated that these cross‐linked films had good hydrophilicity, relative low protein adsorption, and high tensile strength. Also, their swelling behavior varied with the solvent.
Structure of the hyperbranched poly(amine‐ester). 相似文献
This review discusses interfacial layers in organic photovoltaic devices. The first part of the review focuses on the hole extraction layer, which is located between a positive electrode and an organic photoactive material. Strategies to improve hole extraction from the photoactive layer include incorporation of several different types of hole extraction layers, such as conductive polymeric materials, self‐assembled molecules and metal oxides, as well as surface treatment of the positive electrodes and the conductive polymeric layers. In the second part, we review recent research on interlayers that are located between a negative electrode and a photoactive layer to efficiently extract electrons from the active layer. These materials include titanium oxides, metal fluorides and other organic layers.
A general and rigorous new formulation of the multicomponent extension to the Mayo Lewis copolymerization equation is presented based in matrix notation. In contrast to the original Walling and Briggs formulation, which was based on determinants and difficult to apply in practice, this new formulation is explicit, easy to implement, and introduces a natural scaling to the problem. The approach is illustrated with calculation of instantaneous composition and compositional drift with conversion for 4 and 6 monomers.
Summary: The synthesis of a hyperbranched polymer containing a rhenium bipyridine complex is reported. The polymer was synthesized from a monomer that contains two chlorotricarbonyl rhenium(I ) bipyridine moieties and a stilbazole ligand, and the polymer was formed by the coordination reaction in one single step. Gel permeation chromatography results showed that the resulting polymer had a strong interaction with the column packing material, which was reduced when the eluent was added with an electrolyte. Both atomic force microscopy and laser light scattering showed that the size of the polymer molecules was in the range between 25–30 nm. A monolayer of polymer molecules could form on a pretreated substrate by the self‐assembly process, which can serve as the building block for multilayer ultrathin film devices.
The metal‐containing hyperbranched polymer synthesized here. 相似文献
Spin‐coating a mixture solution of P3HT and PCBM on a cold substrate largely enhanced the power conversion efficiency (PCE) of the bulk heterojunction (BHJ) solar cells. This concept was based on the abrupt decrease in the solubility of P3HT as solution temperature decreased. The selective precipitation of P3HT on the PEDOT:PSS‐coated cold substrate facilitated a desirable rich composition of P3HT at the interface with the PEDOT:PSS layer. The high crystallinity of P3HT suppressed the movement of PCBM during thermal annealing, preventing aggregation of PCBM. The morphological excellence of the pristine film gave a comparable PCE to that made by the conventional fabrication process. After thermal annealing, the device made via coating on a cold substrate showed above 30% increase in PCE from the BHJ solar cells made by the conventional method.
Highly dispersed ZnO nanoparticles with variable particle sizes were successfully prepared within an amphiphilic hyperbranched polyetherpolyol matrix via decomposition of an organometallic precursor in the presence of air leading to stable nanocomposites. The high degree of stabilization during and after the synthesis by the polymer permits control over the nanoparticle size and therefore, due to the quantum‐size‐effect, the particle properties. Furthermore, these polymer‐inorganic nanocomposites can easily be dispersed in apolar solvents to yield highly transparent, stable solutions.
Summary: We study the impact of topological disorder on the mechanical response of hyperbranched macromolecules from a theoretical and numerical perspective. The polymer models are generated using a bond switching algorithm, and the emerging systems are described within the Zimm and Rouse pictures of macromolecular dynamics. The topological disorder is manifest in the frequency‐dependent dynamic moduli, . These are clearly distinct from that of regular hyperbranched fractals of the same size, and they do not obey simple scaling rules. The dynamic moduli reflect the short‐range order inherent in the model, and we thus suggest that the extent of disorder in branched tree‐like polymers may be well‐estimated experimentally using .
This work focused on the synthesis and aqueous self‐assembly of a series of novel hyperbranched star copolymers with a hyperbranched poly[3‐ethyl‐3‐(hydroxymethyl)oxetane] (HBPO) core and many linear poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) arms. The copolymers can synchronously form unimolecular micelles (around 10 nm) and large multimolecular micelles (around 100 nm) in water at room temperature. TEM measurements have provided direct evidence that the large micelles are a kind of multimicelle aggregates (MMAs) with the basic building units of unimolecular micelles. It is the first demonstration of the self‐assembly mechanism for the large multimolecular micelles generated from the solution self‐assembly of hyperbranched copolymers.
A novel terminal modification agent to endow hyperbranched polyamidoamine (HPAMAM) with thermo‐/pH‐responsive properties is reported. HPAMAM with terminal vinyl groups is first synthesized and then end‐capped by 1‐adamantylamine (ADA). The resulting hyperbranched polymer (HPAMAM‐ADA) shows interesting thermo‐responsive properties in aqueous solution, which have been investigated by UV‐vis spectroscopy, optical microscopy, and 1H NMR spectroscopy. The lower critical solution temperature can be controlled by adjusting the end‐capping ratio of ADA. In addition, HPAMAM‐ADA exhibits a pH‐dependent water solubility. This pH‐responsive behavior is also studied.
This article provides a comprehensive review of the synthesis, properties and applications of organometallic polymers of the transition metals. The different classes of organometallic polymers are described according to their structural make‐up, as well as by their methods of synthesis. A number of examples of each class are given to emphasize the richness and diversity in these areas of research. In addition to linear polymers, hyperbranched, crosslinked, star and dendritic polymers are also described. The properties that transition metal‐containing organometallic polymers possess, as well as the applications that these materials have found in various domains are highlighted.
We report the successful synthesis of transparent thin film of conducting poly(3,4‐ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS) coated monodisperse polystyrene (PS) microspheres via a simple physical adsorption route in an aqueous media and their electrorheological (ER) application under an applied electric field. Due to the insulating PS core, the PEDOT/PSS wrapped PS (PEDOT/PSS/PS) particles possess a low volume conductivity appropriately applied as ER active materials. Tested by a rotational rheometer under an applied electric field, the PEDOT/PSS/PS based ER fluid dispersed in a silicone oil shows a typical Bingham‐fluid behavior with increased yield stresses according to the increase of electric field strength.
Composite films of poly(3,4‐ethylenedioxythiophene) (PEDOT)‐coated over functionalized multiwalled coiled and linear carbon nanotubes (CNTs) have been fabricated by a simple oxidative electropolymerization route. The nanotubular morphology of the polymer–CNT composite is responsible for the lower charge transfer impedance, lower internal resistance, and superior capacitive response in comparison to that shown by the control PEDOT film doped by trifluoromethanesulfonate ions. This facile electrochemistry exhibited by the PEDOT–CNT composite film ensues in a remarkably high coloration efficiency of 367 cm2 · C−1 at 550 nm, hitherto unrealized for PEDOT; thus demonstrating the huge potential the PEDOT–CNT composite film has as cathode for the entire spectrum of electrochromic devices.
