全湿法制备聚合物电致发光器件

利用全溶液方法制备了聚合物电致发光器件并研究了器件的性能。器件的所有膜层,包括发光层和上电极层均采用溶液湿法获得,完全摒弃了真空蒸镀工艺。利用二次溶剂掺杂获得的PEDOT∶PSS聚合物薄膜的电导率达到608.7 S/cm。在240 nm的厚度时,聚合物电极膜层的面电阻约为68 Ω/□; 当膜层厚度为1 μm时,薄膜的面电阻可低于16 Ω/□。采用溶液滴涂方法制备的高电导PEDOT∶PSS聚合物薄膜作为上电极替代通常所用的铝电极,所制备的聚合物发光器件的开启电压约为4 V。     

A new interpretation of electrochemical impedance spectroscopy to measure accurate doping levels for conducting polymers: Separating Faradaic and capacitive currents

We report an electrochemical impedance spectroscopy (EIS) based method to measure the doping level of conducting polymers. Using EIS the Faradaic current and the capacitive charging current can be separated without relying on any unverifiable assumptions. We demonstrate the method for three types of conducting polymer thin films that are the basis for many commercial applications (poly(3,4-ethylenedioxythiophene), poly-3-hexylthiophene and polypyrrole).     

Electrochemical Determination of the Anticancer Herbal Drug Shikonin at a Nanostructured Poly(hydroxymethylated‐3,4‐ethylenedioxythiophene) Modified Electrode

A simple and sensitive method is described for the electrochemical determination of shikonin, a widely used anti‐tumoral agent, based on its electrochemical oxidation at a nanostructured poly(hydroxymethylated‐3,4‐ethylenedioxy‐thiophene) (PEDOT‐MeOH) electrode, which was fabricated by a facile electropolymerization method. Compared with bare and poly(3,4‐ethylenedioxythiophene) (PEDOT) electrodes, the PEDOT‐MeOH film exhibited a distinctly higher activity for the electrooxidation of shikonin. The PEDOT‐MeOH electrode showed a wide linear response for shikonin in the concentration range from 1.0 nM to 10.0 µM with detection limit of 0.3 nM. Furthermore, the PEDOT‐MeOH electrode displayed high stability, good reproducibility and high sensitivity for the detection of shikonin.     

Improving Efficiency of Organic Photovoltaic Cells Using PEDOT:PSS and MWCNT Nanocomposites as a Hole Conducting Layer

In this study, polymeric nanocomposites of poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) and functionalized multi-walled carbon nanotubes (MWCNTs) were spin coated on a pre-patterned ITO glass and used as a hole conducting layer in organic photovoltaic cells. The multi-layered ITO/MWCNT-PEDOT:PSS/CuPc/C60/Al devices were fabricated to investigate the current density-voltage characteristics and power conversion efficiency. The power conversion efficiency obtained from the device with a concentration of 1.0 wt% MWCNT in the PEDOT:PSS layer was increased twice as those adopted from device without MWCNT doping in the PEDOT:PSS layer and current density-voltage characteristics was also improved well with incorporation of MWCNTs.     

OCVD polymerization of PEDOT: effect of pre‐treatment steps on PEDOT‐coated conductive fibers and a morphological study of PEDOT distribution on textile yarns

The functionalization of textile fibers with intrinsically conductive polymers has become a prominent research area throughout the world. A number of coating techniques have already been utilized and optimized to get the uniform layers of conductive polymers on the surface of different substrates. In our previous study, we produced poly(3,4‐ethylenedioxythiophene) (PEDOT)‐coated conductive fibers by employing oxidative chemical vapor deposition (oCVD) technique. This paper describes the effects of pre‐treatment steps, such as surface treatment of textile fibers with organic solvents, drying of oxidant‐enriched fibers at variable temperatures and time, and oxidant type on the electrical, mechanical, and thermal properties of PEDOT‐coated conductive fibers. Two well‐known oxidants, ferric(III)chloride and ferric(III)p‐toluenesulfonate (FepTS), were studied, and then their results were compared. In order to verify the PEDOT‐coated layer and, to some extent, its impregnation inside the viscose yarns, a morphological study was carried out by using the attenuated total reflectance Fourier transform infrared spectroscopic imaging technique and computed tomography scanning across the obtained conductive fibers. Differential scanning calorimetric and thermogravimetric analysis were utilized to investigate the thermal properties and the contents of PEDOT in PEDOT‐coated fibers. The mechanical properties of conductive fibers were evaluated by tensile strength testing of produced fibers. Effects of all of these pre‐treatment steps on electrical properties were analyzed with Kiethly picoammeter. This study cannot only be exploited to improve the properties of conductive fibers but also to optimize the oCVD process for the production of conductive textile fibers by coating with different conjugated polymers. Copyright © 2012 John Wiley & Sons, Ltd.     

The nearly 100% filling of PEDOT in TiO2 nanotube array by a simple electropolymerization method

A nearly 100% filling of PEDOT in TiO₂ nanotube array (NTA) was successfully prepared by a simple electropolymerization method at a constant potential of 1.8 V, which was demonstrated by field emission scanning electron microscopy (FESEM). UV–vis diffusion reflection spectroscopy (DRS) revealed that the filling of PEDOT in TiO₂ NTA can dramatically improve the visible-light and near-infra-red absorption property of the TiO₂ NTA, which is especially useful for the application of solar cells. Cyclic voltammetry experiments indicate that the PEDOT–TiO₂ NTA hybrid material is electrochemically more active than the TiO₂ NTA and has excellent redox reversibility.     

Amperometric Detection and Quantification of Nitrate Ions Using a Highly Sensitive Nanostructured Membrane Electrocodeposited Biosensor Array

In the past few decades, there has been a steady rise in the release of nitrate (NO₃^?), a prominent water soluble contaminant associated with the increasing use of nitrate based fertilizers. In this study, we suggest the use of a highly sensitive, enzymatic biosensor capable of quantifying minute concentrations of nitrate. The disposable nitrate biosensor consists of a sensing element in the form of nitrate reductase which is immobilized within a conductive polymer matrix to generate a quantifiable amperometric response. In this work, nanoarrays of co‐immobilized nitrate reductase and poly(3,4‐ethylenedioxythiophene) (PEDOT), were grown using a template assisted electropolymerization route. The performance of the biosensor is a strong function of electropolymerization conditions and the morphology of the PEDOT nanostructures. The electropolymerized biosensor displays excellent specificity w.r.t other interfering ions as evidenced from the initial rate kinetics. With a response time of a few seconds, limit of detection (LOD) as low as 0.16 ppm and sensitivity of about 92 µA/mM , the one‐step electropolymerized nanostructured nitrate biosensor developed in this study shows improved performance compared to similar electrochemical sensors reported in literature. The PEDOT/nitrate reductase nanowire sensor developed in this work shows superior attributes compared to a flat 2D nitrate reductase‐co‐immobilized PEDOT film grown using similar electropolymerization conditions. This combined with easy and fast fabrication technique opens up exciting opportunities for developing high accuracy PEDOT based nanobiosensors for field testing of nitrate contaminants in the future.     

An Unconventional Route to Monodisperse and Intimately Contacted Semiconducting Organic–Inorganic Nanocomposites

We developed an unconventional route to produce uniform and intimately contacted semiconducting organic–inorganic nanocomposites for potential applications in thermoelectrics. By utilizing amphiphilic star‐like PAA‐b‐PEDOT diblock copolymer as template, monodisperse PEDOT‐functionalized lead telluride (PbTe) nanoparticles were crafted via the strong coordination interaction between PAA blocks of star‐like PAA‐b‐PEDOT and the metal moieties of precursors (i.e., forming PEDOT–PbTe nanocomposites). As the inner PAA blocks are covalently connected to the outer PEDOT blocks, the PEDOT chains are intimately and permanently tethered on the PbTe nanoparticle surface, thereby affording a well‐defined PEDOT/PbTe interface, which prevents the PbTe nanoparticles from aggregation, and more importantly promotes the long‐term stability of PEDOT–PbTe nanocomposites. We envision that the template strategy is general and robust, and offers easy access to other conjugated polymer–inorganic semiconductor nanocomposites for use in a variety of applications.     

阳极缓冲层修饰对聚合物太阳能电池性能的影响

为提高聚合物太阳能电池的能量转换效率,将聚乙二醇(PEG)掺入PEDOT∶PSS阳极缓冲层,研究了阳极缓冲层修饰对聚合物太阳能电池性能的影响。首先研究了聚乙二醇对PEDOT∶PSS薄膜电导率的影响,发现PEG会与PEDOT和PSS相互作用,使得PEDOT链重新排布,有利于电荷载流子的传输,从而显著改善了PEDOT∶PSS薄膜的电导率,当PEDOT∶PSS中掺入体积分数为2%~4%的PEG时,可得到较大的电导率。然后,以PEG修饰的PEDOT∶PSS薄膜作为阳极缓冲层制备了聚合物太阳能电池,研究了PEG的掺入对聚合物太阳能电池性能的影响。实验发现,PEG改善的PEDOT∶PSS电导率有利于提高电池的短路电流密度和填充因子,从而改善了器件光伏性能。当PEDOT∶PSS中掺入体积分数为2%的PEG时,聚合物太阳能电池的能量转换效率最高,比未掺杂的器件提高了24.4%。     

Surface-enhanced Raman scattering of EDOT and PEDOT on silver and gold nanoparticles

Surface-enhanced Raman scattering (SERS) spectra of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and its monomer 3,4-ethylenedioxythiophene (EDOT) on Ag and Au nanoparticles presenting different morphologies and stabilizing agents have been obtained using the excitation radiation at 633 nm. The SERS spectra of the monomer and polymer are strongly dependent both on the metal and capping agent of the substrate. SERS spectra of EDOT on Au nanospheres indicates that adsorption occurs with the thiophene ring perpendicular to the metal surface. In contrast, polymerization takes place on the silver surface of Ag nanospheres. EDOT adsorption on Ag nanoprisms with polyvinylpyrrolidone (PVP) as capping agent occurs similarly to that observed on gold. Surface-enhanced resonance Raman scattering (SERRS) spectra of PEDOT on gold nanostars that present a thick layer of PVP show no chemical interaction of PEDOT with the metal surface; however, when PEDOT is adsorbed on citrate stabilized gold nanospheres, the SERRS spectra suggest that thiophene rings are perpendicular to the surface. Oxidation of PEDOT also is observed on Ag nanospheres. The investigation of the interface between PEDOT and metal surface is crucial for the development in polymer-based optoelectronic devices since this interface plays a crucial role in their stability and performance.