Poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate): Correlation between colloidal particles and thin films

We deal with correlation between sizes of colloidal particles and minimum thickness of spin-coated thin films of poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS) studied by a dynamic light scattering (DLS), a scanning transmission electron microscopy coupled with an energy dispersive X-ray spectroscopy (STEM-EDX), C₆₀-sputtering X-ray photoelectron spectroscopy (XPS), and an atomic force microscopy. Based on the various measurements, it was pointed out that, PEDOT/PSS colloidal dispersion contained majority of primary nanoparticles with mean diameter of 41 nm and 16 nm for BAYTRON P AG (denote P grade) or BAYTRON PH500 (denote PH grade) solutions, respectively, and small amount of clusters aggregated by the primary particles, based on the DLS measurement and STEM observation. On the other hand, PEDOT/PSS thin films with thickness of 44 nm and 16 nm were easily prepared by spin-coating on silicon wafers from the P and PH grade solutions, respectively. Results of STEM-EDX, DLS, and XPS measurements suggested that the PEDOT/PSS thin films consist of the randomly packed primary nanoparticle-“monolayer”.     

Enhancement of poly(3,4-ethylenedioxy thiophene)/poly(styrene sulfonate) properties by poly(vinyl alcohol) and doping agent as conductive nano-thin film for electronic application

In this work, the integration of the useful concepts of polymer blending and doping agent to simultaneously improve various properties of poly(3,4-ethylene dioxy thiophene) poly(styrene sulfonate) (PEDOT:PSS) nano-thin films was shown. According to the polymer-blending concept, insulating poly(vinyl alcohol) (PVA) has a good deal of potential to be utilized as a filler to improve the critical properties of the PEDOT:PSS matrix, especially conductivity, wettability, and thermal and mechanical properties. At the appropriate amount of PVA, 0.08 wt%, it acts as a binder to improve the connection network between PEDOT:PSS chains, leading to a maximum conductivity of 1.18 S/cm, and also providing a good contact angle of 8.8°. The transmission of the films decreased with increasing PVA content; however, all specimens still showed excellent transmittance values of more than 80 %. The thermal stability and the resistance to abrasion of the nano-thin conductive films were improved by strong covalent bonds between PVA and PSS, which were verified by TGA and a scratching test, respectively. In addition, the relationship of PEDOT:PSS properties versus various amounts of insulating PVA for practical usage for specific electronic fields were shown. Use of the doping agent quinoxaline was aimed to particularly enhance the conductivity of PEDOT:PSS. The highest conductivity (2.75 S/cm) was achieved when 0.5 wt% quinoxaline was added into 0.08 wt% PVA/PEDOT:PSS while the other properties were not significantly altered.     

Multiwall carbon nanotube and poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) composite films for transistor and inverter devices

Highly conductive multiwalled carbon nanotube (MWNT)/Poly(3,4-ethylenedioxythiophene) polymerized with poly(4-styrenesulfonate) (PEDOT:PSS) films were prepared by spin coating a mixture solution. The solution was prepared by dispersing MWNT in the PEDOT:PSS solution in water using ultrasonication without any oxidation process. The effect of the MWNT loading in the solution on the film properties such as surface roughness, work function, surface energy, optical transparency, and conductivity was studied. The conductivity of MWNT/PEDOT:PSS composite film was increased with higher MWNT loading and the high conductivity of MWNT/PEDOT:PSS films enabled them to be used as a source/drain electrode in organic thin film transistor (OTFT). The pentacene TFT with MWNT/PEDOT:PSS S/D electrode showed much higher performance with mobility about 0.2 cm2/(V s) and on/off ratio about 5 × 10? compared to that with PEDOT:PSS S/D electrode (～0.05 cm2/(V s), 1 × 10?). The complementary inverters exhibited excellent characteristics, including high gain value of about 30.     

Properties of one-step synthesized Pt nanoparticle-doped poly(3,4-ethylenedioxy thiophen):poly(styrenesulfonate) hybrid films

Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) thin films incorporating Pt nanoparticles were synthesized by a simple method using H₂PtCl₆? xH₂O. The surface morphology, chain structure, bonding states, and electronic structure of the films were investigated. Unusual formation of a PEDOT-rich surface was accompanied with interactions between PEDOT:PSS and Pt nanoparticles due to agglomeration of PEDOT:PSS around Pt nanoparticles and destabilization of chain conformation. High doping of the PEDOT moiety occurred during the reduction of H₂PtCl₆·xH₂O so that an increased work function and a decreased energy gap between the edge of the highest occupied molecular orbital and the Fermi level were observed. Intermediate products including chlorine and [PtCl₆]⁻, and the ionic nature of the Pt nanoparticles were responsible for the resultant properties of Pt-PEDOT:PSS. Products generated during the formation of Pt nanoparticles served as a third anionic dopant like PSS and as an inhibitor of segregation.     

溴掺杂对PEDOT/PSS薄膜性能的影响及机理研究

为改善聚乙撑二氧噻吩∶聚（对苯乙烯磺酸）根阴离子（PEDOT/PSS）薄膜的光学及电学性能,采用共混-旋涂法在石英玻片上制备出溴掺杂的PEDOT/PSS透明导电膜,并就其掺杂导电机理进行了探讨.结果表明：经微量溴掺杂后的PEDOT/PSS薄膜,其透光性能与导电性能均得到提高;质量分数6%溴掺杂条件下,薄膜透光率为95....     

Conductivity enhancement of PEDOT:PSS thin film using roll to plate technique and its characterization as a Schottky diode

The conductivity of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) was improved by pressing the PEDOT:PSS thin film using roll to plate system. PEDOT:PSS thin film was deposited on polyethylene terephthalate using electrohydrodynamics atomization technique. The physico-chemical properties of the pressed thin film at different loads were compared with an un-pressed sample. The electrical properties show that the film conductivity has been increased by four times. An optimized pressing load was found to have good conductivity and transmittance of the thin film. A hybrid device (PEDOT:PSS/F8BT/ZnO/Ag) was fabricated using layer by layer method with PEDOT:PSS as anode. The I–V characterization showed that the device with pressed PEDOT:PSS showed higher current densities. The results give a promising future of PEDOT:PSS in electronics device applications using printed electronics techniques.     

The thermoelectric performance of carbon black/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) composite films

Carbon black/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (CB/PEDOT:PSS) composite films have been prepared by a spin-coating method. The morphology of the composite films was investigated by field emission scanning electron microscopy and atomic force microscopy. The thermoelectric properties of CB/PEDOT:PSS composite films were measured at room temperature. As the content of CB increased from 0 to 11.16 wt%, the electrical conductivity of the composite films first increased sharply and then decreased, while the Seebeck coefficient increased slowly. A highest power factor of 0.96 μWm^?1 K^?2 was obtained.     

Ultrasonically sprayed and inkjet printed thin film electrodes for organic solar cells

Thin film pi-conjugated poly(3,4ethylenedioxythiophene): poly(styrenesulphonate) (PEDOT:PSS) as a hole transport layer on indium tin oxide is a key element in some of the most efficient organic photovoltaic and light emitting devices to date. Films are typically deposited by spincoating, which is not readily scalable. In this paper we investigate the critical parameters for both inkjet and ultrasonic spray deposition of PEDOT:PSS thin films on commercial indium tin oxide as a potentially scalable approach to contact formation. Inkjet parameters investigated include drop spacing and substrate temperature. Ultrasonic spray coating parameters investigated include substrate temperature and solution flow rate. We also show that the ink viscosity has a Newtonian character, making it well suited for inkjet printing. Films were characterized via optical profilometry, sheet resistance and atomic force microscopy. Optimized inkjet printed and ultrasonic sprayed PEDOT:PSS films were then compared to spincast layers in a prototypical bulk heterojunction photovoltaic device employing a poly(3-hexylthiophene) and [6,6]-PCBM (6,6-phenylC61-butric acid-methyl ester) blend as the absorber. Practically all three approaches produced devices of comparable efficiency. Efficiencies were 3.6%, 3.5% and 3.3% for spin, spray and inkjet depositions respectively.     

Fabrication of poly(FOMA-b-EO)/silver nanocomposite hybrid films

A facile synthesis of silver nanoparticles (with a diameter of 5 nm)/polymer hybrid films was studied through auto-reduction of silver nitrate (AgNO3) in poly(1H,1H-dihydroperfluorooctyl methacrylate-b-ethylene oxide) (poly(FOMA(10k)-b-EO(10k micellar thin films at ambient temperature. Silver nanoparticles well dispersed in the block copolymeric micellar films were prepared by rendering the silver precursor AgNO3 to interact favorably with PEO blocks. With annealing of the micellar film containing AgNO3 in supercritical CO2, the domains and continuous phase of the micellar film morphology were inverted and silver nanoparticles with a diameter of 10 nm were produced in PEO domains. The synthesis of silver nanoparticles in the copolymeric films was confirmed by transmission electron microscope and UV-visible spectrophotometric analysis.     

Grating-coupled surface plasmon enhanced short-circuit current in organic thin-film photovoltaic cells

In this study, we demonstrate the fabrication of grating-coupled surface plasmon resonance (SPR) enhanced organic thin-film photovoltaic cells and their improved photocurrent properties. The cell consists of a grating substrate/silver/P3HT:PCBM/PEDOT:PSS structure. Blu-ray disk recordable substrates are used as the diffraction grating substrates on which silver films are deposited by vacuum evaporation. P3HT:PCBM films are spin-coated on silver/grating substrates. Low conductivity PEDOT:PSS/PDADMAC layer-by-layer ultrathin films deposited on P3HT:PCBM films act as the hole transport layer, whereas high conductivity PEDOT:PSS films deposited by spin-coating act as the anode. SPR excitations are observed in the fabricated cells upon irradiation with white light. Up to a 2-fold increase in the short-circuit photocurrent is observed when the surface plasmon (SP) is excited on the silver gratings as compared to that without SP excitation. The finite-difference time-domain simulation indicates that the electric field in the P3HT:PCBM layer can be increased using the grating-coupled SP technique.     

Enhanced ferroelectric and dielectric properties of the P(VDF-TrFE)/Ag nanoparticles composite thin films

The scope of the present work was the synthesis of homogeneously dispersed silver (Ag) nanoparticles (NPs) in P(VDF-TrFE) polymer by N,N-dimethylformamide’s reducing reaction on silver nitrate and the study on the surface micromorphology, crystalline phases, electrical and optical properties of the P(VDF-TrFE)/Ag NPs composite thin films. The results demonstrate that incorporating appropriate concentration of Ag NPs improve the ferroelectric and dielectric properties with an increase of 38 % in the remanent polarization and 47 % in dielectric constant respectively compared with the pristine P(VDF-TrFE) films. The reasons for the improved properties are explained by the effective compensation to the bounding charges provided by the appropriate amount of the Ag NPs fillers and Ag NPs’ acting as micro capacitors in P(VDF-TrFE) matrix. Furthermore, the surface plasmon resonance absorption in the composite films thin films is observed at the wavelength of ~415 nm, whose intensity is dependent on the density of the Ag NPs.     

Control of the Surface Morphology of Ceramic/Polymer Composite Inks for Inkjet Printing

The use of organic/inorganic composite inks in the Drop on Demand inkjet printing technology is a promising as well as demanding approach for the fabrication of composite thick films. Therefore, a versatile ceramic/polymer composite ink system for inkjet printing is developed in this study, containing Ba_0.6Sr_0.4TiO₃ (BST) and poly(methyl methacrylate) (PMMA). When developing such inks suitable for a one‐step fabrication, the major challenge is to fulfill the requirements of the inkjet printing technology and to obtain homogeneous surface morphologies after drying. Thus, possible influencing factors like the solvent composition, the solids content, and the ratio of ceramic to polymer are investigated to obtain a detailed knowledge for the general ink development. The fluid mechanical properties, viscosity, density, and surface tension are characterized. The main focus of this study lies on the drying behavior of the different inks, with the interactions of the ceramic particles, and the dissolved polymer molecules being highlighted. Furthermore, the drying behavior depending on the ink composition is shown. This study provides new insights into the possibility of using composite inks for the inkjet printing process and the fabrication of printed composite thick films in a single process step.

     

用于喷墨打印的Ag2Se墨水的制备及表征

制备硒化银(Ag₂Se)薄膜材料对于组装微型器件至关重要, 目前大部分制备方法难以精确控制薄膜尺寸并进行图案化设计, 喷墨打印技术成为解决这一问题的有效方法, 实现其与Ag₂Se材料的组合具有重要意义。本工作通过溶剂热法制备了Ag₂Se纳米颗粒, 再与不同分散剂混合以筛选出适用于喷墨打印的稳定墨水, 进一步调节喷射参数以优化打印过程中墨滴的形态, 提高打印质量。将墨水打印至聚酰亚胺衬底上, 经热处理后制备得到Ag₂Se薄膜。使用不同手段对其物相与微结构进行表征, 并测试不同打印层数薄膜的电学性能。结果表明: 随着墨水固含量与打印层数增加, Ag₂Se薄膜的结晶度和致密度得到明显提升, 电导率也得到相应提高, 这主要源于薄膜内部Ag₂Se纳米颗粒沉积量与堆积密集程度增加。当使用固含量为5 mg·mL^-1的墨水进行打印, 打印层数为40层时, Ag₂Se薄膜的电导率达到399 S·cm^-1, 表现出较高的导电性能。本研究为制备Ag₂Se基薄膜材料与器件提供了新的方向。     

An Efficiently Doped PEDOT:PSS Ink Formulation via Metastable Liquid−Liquid Contact for Capillary Flow-Driven,Hierarchically and Highly Conductive Films

With commercial electronics transitioning toward flexible devices, there is a growing demand for high-performance polymers such as poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS). Previous breakthroughs in promoting the conductivity of PEDOT:PSS, which mainly stem from solvent-treatment and transfer-printing strategies, remain as inevitable challenges due to the inefficient, unstable, and biologically incompatible process. Herein, a scalable fabrication of conducting PEDOT:PSS inks is reported via a metastable liquid−liquid contact (MLLC) method, realizing phase separation and removal of excess PSS simultaneously. MLLC-doped inks are further used to prepare ring-like films through a compromise between the coffee-ring effect and the Marangoni vortex during evaporation of droplets. The specific control over deposition conditions allows for tunable ring-like morphologies and preferentially interconnected networks of PEDOT:PSS nanofibrils, resulting in a high electrical conductivity of 6,616 S cm⁻¹ and excellent optical transparency of the film. The combination of excellent electrical properties and the special morphology enables it to serve as electrodes for touch sensors with gradient pressure sensitivity. These findings not only provide new insight into developing a simple and efficient doping method for commercial PEDOT:PSS ink, but also offer a promising self-assembled deposition pattern of organic semiconductor films, expanding the applications in flexible electronics, bioelectronics as well as photovoltaic devices.     

Poly(aniline-co-m-aminobenzoic acid) deposited on poly(vinyl alcohol): Synthesis and characterization

In this work, we have deposited poly(aniline-co-m-aminobenzoic acid) on poly(vinyl alcohol) (PVA) by in situ polymerization. The polymerization was effected within maleic acid (MA) cross-linked PVA hydrogel. The copolymer was obtained by oxidative polymerization of aniline hydrochloride and m-aminobenzoic acid using ammonium persulfate as an oxidant. Instead of conventional solution polymerization, here synthesis was carried out on APS soaked MA cross-linked PVA (MA–PVA) film where the polymer was in situ deposited in its conducting form. The composite film was characterized by Fourier transform infra red (FT–IR) and ultraviolet visible (UV–VIS) spectroscopy and electrical measurements. Surface morphology of the composite films was studied by field emission scanning electron microscopy (FESEM). The variation of conductivity of the films was studied.     

Properties of polyacrylic acid-coated silver nanoparticle ink for inkjet printing conductive tracks on paper with high conductivity

Silver nanoparticles with a mean diameter of approximately 30 nm were synthesized by reduction of silver nitrate with triethanolamine in the presence of polyacrylic acid. Silver nanoparticle-based ink was prepared by dispersing silver nanoparticles into a mixture of water and ethylene glycol. The mechanism for the dispersion and aggregation of silver nanoparticles in ink is discussed. The strong electrostatic repulsions of the carboxylate anions of the adsorbed polyacrylic acid molecules disturbed the aggregation of metal particles in solutions with a high pH value (pH > 5). An inkjet printer was used to deposit this silver nanoparticle-based ink to form silver patterns on photo paper. The actual printing qualities of the silver tracks were then analyzed by variation of printing passes, sintering temperature and time. The results showed that sintering temperature and time are associated strongly with the conductivity of the inkjet-printed conductive patterns. The conductivity of printed patterns sintered at 150 °C increased to 2.1 × 10⁷ S m⁻¹, which was approximately one third that of bulk silver. In addition, silver tracks on paper substrate also showed better electrical performance after folding. This study demonstrated that the resulting ink-jet printed patterns can be used as conductive tracks in flexible electronic devices.     

Combined electrochromic and plasmonic optical responses in conducting polymer/metal nanoparticle films

Poly(3,4-ethylenedioxithiophene)/poly(styrene sulphonate) (PEDOT/PSS) aqueous dispersions were mixed with aqueous gold nanoparticle and aqueous silver nanoparticle colloids. PEDOT/gold nanoparticles (Au NP) and PEDOT/silver nanoparticles (Ag NP) films were obtained by solvent casting the corresponding aqueous solutions. The nanocomposite films showed the optical characteristics associated with both the surface plasmon absorption resonance of the metal nanoparticles and the excitation of the bipolaron band of the conducting polymer. As an interesting application we demonstrate the use of metal nanoparticles to tune the color of PEDOT based electrochromic films from blue to violet in the case of Au NP or green in the case of Ag NP.     

Drift in the resistance of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) printed films during thermal cycling

We report on the investigation of the suitability of printed poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films for temperature sensing devices. Gravure printing with the advantage of low cost production was used to prepare thin films of PEDOT:PSS on a flexible foil substrate. The electrical resistance was studied during thermal cycling and exposure to elevated constant temperatures. A drift of the resistance which depends on time, temperature and sample makes the usage as simple temperature sensors not possible. However, a closer look on the drift of relative resistances reveals that integrated temperature-time-profiles can be measured, which might be interesting in connection with monitoring of conditions of storing and transport of sensitive goods.     

Controlled doping of double walled carbon nanotubes and conducting polymers in a composite: An in situ Raman spectroelectrochemical study

The interaction of double wall carbon nanotubes (DWCNTs) and the conducting polymer poly(3,4-ethylenedioxythiphene)/polystyrenesulfonate (PEDOT/PSS) was studied by in-situ Raman spectroelectrochemistry. The mixing of DWCNTs with PEDOT/PSS caused a partial doping of the outer tube of DWCNTs, which was indicated by the relative change of the Raman intensity of the DWCNTs features. On the other hand, the bands corresponding to inner tubes of DWCNTs and to the polymer were almost untouched by assembling both species into a composite. The in-situ Raman spectroelectrochemical experiments have shown that the changes in electronic structure of inner tubes of DWCNTs embedded in PEDOT/PSS matrix are dependent on the doping level. While at the low doping level of the composite, the Raman features of inner tubes of DWCNTs do not change significantly, at high doping level they reflect the changes caused by the applied electrochemical potential similar to those observed in the polymer-free DWCNTs.     

Preparation and characterization of conducting poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) Langmuir-Blodgett film

The self-assembly of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) nanoparticles at an air/water interface was achieved by means of the electrostatic force between an octadecylamine (ODA) monolayer and PEDOT-PSS nanoparticles. A surface pressure (π)-area (A) isotherm and X-ray photoelectron spectroscopy of the composite film were used to confirm the electrostatic force between the SO₃⁻ group of PSS and the NH₄⁺ group of aliphatic amines. Monolayer and multilayer composite films of ODA/PEDOT-PSS and ODA-stearic acid (SA)/PEDOT-PSS were fabricated. These solid Langmuir-Blodgett films were investigated by the UV-Vis spectrum, atomic force microscopy, and X-ray diffraction method. It is observed that ODA-SA/PEDOT-PSS films had a higher film-forming capability than ODA/PEDOT-PSS films and an ordered multilayer structure was developed. The conductive properties of ODA-SA/PEDOT-PSS LB films were investigated in detail. Factors influencing the film conductivity such as the layer number and surface pressure were discussed and the conductive mechanism was also studied.