Investigation of electrospray-deposited PEDOT:PSS thin film using an electrohydrodynamic jet printer for inverted QDLEDs

Journal of Materials Science: Materials in Electronics - In general, Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) is spin-coated as a hole transport layer in multi-structured...     

Preparation of a working electrode with a conducting PEDOT:PSS film and its applications in a dye-sensitized solar cell

This study investigates the applicability of a working electrode with a poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) film on a dye-sensitized solar cell (DSSC). This working electrode was designed and fabricated by inserting a PEDOT:PSS film between a fluorine-doped tin oxide (FTO) glass substrate and a layer of nanocrystalline TiO₂ particles (P-25). This study also examines the effects of annealing temperature and duration on the transmittance and microstructure of a PEDOT:PSS film as well as the power conversion efficiency of DSSC with this film. The power conversion efficiency of a DSSC with a PEDOT:PSS film (6.37%) substantially exceeds that of a conventional DSSC (4.24%). This result is attributed to the fact that this transparent and conductive PEDOT:PSS film deposited on the FTO glass substrate using a simple spin coating method substantially improves the short-circuit photocurrent per unit area and the fill factor of DSSC.     

PEDOT:PSS as back contact for CdTe solar cells and the effect of PEDOT:PSS conductivity on device performance

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was studied as the back contact of Cadmium telluride (CdTe) solar cells and was compared with conventional Cu-based back contact. A series of PEDOT:PSS aqueous solutions with different conductivities were spin coated onto the glass/SnO2:F/SnO2/CdS/CdTe structures as back contact, and the PEDOT:PSS conductivity dependence of device performance was studied. It was found that PEDOT:PSS back contact with higher conductivity produces devices with lower series resistance and higher shunt resistance, leading to higher fill factor and higher device efficiencies. As the conductivity of PEDOT:PSS increased from 0.03 to 0.24 S/cm, the efficiency of the solar cell increased from 2.7 to 5.1 %. Methanol cleaning also played an important role in increasing the device performance. The efficiency of our best device with PEDOT:PSS back contact has reached 9.1 %, approaching those with conventional Cu/Au back contact (12.5 %).     

Indentation mechanics and its application to thin film characterization

Instrumented indentation mechanics and its applications to thin film characterization are described and discussed. Instrumented nanoindentation has become an outstanding tool for characterizing coatings and treated surfaces. It is routinely used in industry and university allowing for determining the mechanical performance of coated and treated pieces, that is of primary importance for keeping new surface functionality in time. The paper reviews important procedures and concepts that have proved to be very useful to analyse the contact response (elastic unloading, indentation strains and stresses, composite response of coated pieces). Examples are used to illustrate the very wide range of studies that can be carried out.     

生物质衍生没食子酸增强PEDOT:PSS膜导电性能及其调控机制

聚3, 4-乙烯二氧噻吩(PEDOT)因其具有柔性可拉伸、生物相容性高、导电及功函数可调控等优势在柔性可穿戴电子器件中显示出广阔的应用前景。近年来,随着资源危机的日益凸显,针对PEDOT:聚苯乙烯磺酸(PSS)体系,研究开发高效绿色可持续的生物质基掺杂剂,已引起相关研发人员的高度关注。本研究首次报道了采用生物质芳香弱酸?没食子酸(GA,pKa为4.41)掺杂制备高性能PEDOT导电膜的新途径。GA独特的邻多酚羟基结构创造了稳定的GA-PSSH双氢键,使得GA-PSSH的分子结合能显著高于GA的石油基强酸异构体(2, 4, 6-三羟基苯甲酸,pKa=1.68)与PSSH的分子结合能。GA掺杂不仅可实现PEDOT-PSS的高效相分离,而且优化了PEDOT分子链的构象、聚集结构的形貌及其排列方向。这赋予GA具有很高的掺杂效率,当GA掺杂量为1.2%时,PEDOT导电膜的电导率可提升三个数量级,达到1050 S/cm,导电性能达到已报道的生物质基掺杂剂的最高水平,且掺杂效率明显优于其它生物质基掺杂剂及其石油基强酸异构体。      

Optical and electronic characterization of transition layer in thin film Au-GaAs Schottky barrier

The possibility of determination of optical parameters and thickness of interfacial oxide (IO) layer by multiple-angle-of-incidence (MAI) ellipsometry has been studied for Au-IO-GaAs structures with different oxide thickness. The films parameters have been calculated by the original program of inverse ellipsometric problem solution. Parameters of oxide layer have been determined both for free GaAs surface and for that covered by Au film. Gold film was prepared by vacuum evaporation on the heated n-n+GaAs substrate. Its parameters have been determined by MAI ellipsometry and transparency measurements of Au-quartz satellite system. The investigation showed the change of optical parameters of GaAs oxide layer after the Au evaporation. In the assumption of invariable thickness of IO layer its optical parameters are : n = 1.0±0.1, k = 0.4 ÷ 0.6. The mechanism of current transport and electrical parameters of Au-IO-GaAs structures have been determined from I-V and C-V characteristics of Schottky diodes. The results of the determination of transition layer thickness to its dielectric constant ratio (d\_i)) from electrical characteristics of barrier also indicate its difference from initial parameters of oxide layer probably due to interdiffusion of Au, Ga, and As.     

Preparation and performance enhancement study of organic ZnO/Au/PEDOT:PSS heterojunction UV photodetector

Journal of Materials Science: Materials in Electronics - Organic/inorganic hybrid material properties and their interfaces are essential to obtain excellent device performance. In this paper, an...     

Preparation and characterization of tin diselenide thin film by spray pyrolysis technique

Tin diselenide (SnSe₂) thin film is deposited on to non-conducting glass substrate by spray pyrolysis technique at an optimized substrate temperature of 523 K. Hot probe method is used to identify the type of conductivity of the film to be an n-type semiconductor. X-ray diffraction study reveals the polycrystalline nature of the film with a preferential orientation growth. Spherical shaped grains with an average diameter of 233 nm are observed from the SEM photograph. The elemental composition on the surface of the film is analyzed with EDAX spectrum and formed almost in stoichiometric in composition. Room temperature resistivity of 1.27 × 10⁴ Ω cm is determined using the linear four-probe method. Activation energy of 0.058 eV is determined by studying the variation of resistivity of the film with temperature. Optical absorption spectrum of this sprayed SnSe₂ thin film is analyzed and found to have a direct allowed transition with a band gap of 1.48 eV.     

Substrate treatment and drying conditions effect on the properties of roll-to-roll gravure printed PEDOT:PSS thin films

The optical, structural and electrical properties of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonic acid) (PEDOT:PSS) thin films printed by roll-to-roll gravure have been investigated. Corona treatment has been applied to enhance the adhesion of PEDOT:PSS on PolyEthylene Terephthalate (PET) web. It has been found that there was a stronger in-depth surface modification of PET with the increase of corona efficiency; however, the adhesion of PEDOT:PSS was not actually affected. Also, Spectroscopic Ellipsometry and Atomic Force Microscopy have been used to extract information on the mechanisms that define PEDOT:PSS properties. The increase of the drying temperature of the PEDOT:PSS films has been found to reduce the remaining water inside the films and lead to the decrease of the PEDOT:PSS particles size.     

Analytical study of a solution-processed diode based on ZnO nanoparticles using multi-walled carbon nanotubes as Schottky contact

Journal of Materials Science: Materials in Electronics - The search for good electrodes processed by solution has interested several niches to produce printed solar cells, lighting emitting diodes,...     

A compact ion source using a hollow cathode discharge and its application to thin film formation

A compact and simple ion beam source was developed and its application to ion beam sputter deposition of thin films was studied. The ion source consisted of a hollow cathode, an anode and an extraction electrode. Two acceleration electrodes were mounted at the edge of the cathode. Since the gas pressure in the cathode should be kept at a relatively high value (more than 0.05 Torr) to maintain the discharge, the ion source employed a differential pumping system. The fundamental discharge characteristics of the ion source were studied using argon or helium as the working gas.The ion source was applied to the ion beam sputter deposition of copper and ruthenium oxide films. The crystallinity of the copper films increased with an increase in the acceleration voltage, while all the ruthenium oxide films appeared to be amorphous or of very small grain size, regardless of the acceleration voltage. The effect of the acceleration voltage on the film resistivity was also studied.     

Metalorganic chemical vapor deposition of SrRuO3 thin film and its characterization

Synthesis of conducting oxide strontium ruthenate is carried out in a hot-wall tubular reactor, using Sr(C₁₁H₁₉O₂)₂/Ru(C₅H₅)₂/O₂ reaction system. Owing to a large difference in depositing efficiency between strontium and ruthenium precursors, the stoichiometric ratio of thin film is controlled in one cycle of two consecutive depositions at different temperatures. Thin films of SrRuO₃ single phase are synthesized in the subsequent 700°C annealing. Thin films of SrRuO₃ with extra ruthenium oxide can also be prepared by adjusting the molar ratio of RuO₂ and SrO layers. The deposition sequence of ruthenium oxide first, strontium oxide later is preferred. If the deposition sequence is reverse, the thin film is plagued with unreacted oxides even when the annealing temperature is raised to 800°C. The relative ease of preparing SrRuO₃ thin films, when RuO₂ is under SrO, is attributed to evaporation of ruthenium oxide in O₂ and diffusion in its open columnar microstructure. The sheet resistivity of thin film decreases with the ruthenium content. The room temperature resistivity of SrRuO₃ film of Ru/(Sr + Ru) = 0.5 is around 910 ohm-cm. The room-temperature resistivity of Ru/(Ru + Sr) = 0.53 decreases to 470 ohm-cm. The root mean square surface roughness of 700°C synthesized SrRuO₃ thin film is 22 nm, in a 2 × 2 m² area of film thickness 280 nm.     

Fabrication of horizontally grown silicon nanowires using a thin aluminum film as a catalyst

We present a new method for the fabrication of horizontal silicon nanowires for application in nanoelectronic devices. A web of horizontally connected silicon nanowires is grown on a silicon substrate using a thin aluminum film as a catalyst. A thin layer of oxide is thermally grown on a silicon substrate. The oxide layer is then selectively etched using photolithography. A thin layer of aluminum is thermally evaporated on the substrate with the patterned oxide layer. When the sample is annealed above the eutectic temperature, we show that the silicon gets deposited along the grain boundaries of aluminum in the form of thin nanowires. We show that this phenomenon is due to the high solubility of silicon in aluminum at high temperatures.The surface morphology was analyzed using Scanning Electron Microscopy (SEM). The compositional analysis was done using Energy Dispersive X-ray spectroscopy (EDX).     

WO3 thin film prepared by PECVD technique and its gas sensing properties to NO2

Tungsten oxide films have been successfully fabricated from tungsten oxychloride (WOCl₄) precursor by using plasma enhanced vapor deposition (PECVD) technique. The films were deposited onto silicon substrates and ceramic tubes maintained at 100°C under a constant operating pressure of He-O₂ gas mixtures. The compositions and the structures of the thin films have been investigated by means of anaysis methods, such as XRD, XPS, UV and IR. The as-deposited WO₃ thin films were amorphous state and became crystalline after annealing above 400°C. The surface analysis of the films indicates that stoichiometry O/W is 2.77 : 1. The gas sensing measurements of the WO₃ thin film sensors indicate that these sensors have a high sensitivity, excellent selectivity and quick response behavior to NO₂.     

Fabrication of a pure TiO2 thin film using a self-polymeric titania nano-sol and its properties

A pure TiO2 thin film without adding any organic binder was fabricated by using a self-polymeric titania nano-sol (14 mass%), which was prepared by the acid peptization method. The particle size distribution in the 14 mass% TiO2 sol, in which almost of particles had a size below 10.2 nm and the crystal phase confirmed by X-ray diffraction analysis was anatase. The diluted nano-sol had a capability to form a thin film at a low temperature (100-400 degrees C) on the slide glass by dipping method. The average thickness of a coating film was measured to be about 0.25-0.30 microm. A coated film had a high refractive index over 1.88 at least irrespective of the heat-treatment even at room temperature drying and showed a super-hydrophilicity (< 5 degrees) after 20 minutes under Ultra Violet light irradiation, and it sustained in the darkness during a long period over 7 days depending on the heat-treatment conditions. Atomic Force Microscopic observation shows that the morphology of a heat-treated film had a relationship with the long-term hydrophilicity in the darkness.