Development of Siloxane Coating with Oxide Fillers for Kesteritic (CZTS) Photovoltaic Systems

Photovoltaic systems (PV) based on Cu2ZnSn(S, Se)4 (CZTS) solar cells have demonstrated efficiency and high performance. According to the results of comparative studies, the kesterite structure has proven to be ecologically safe and less expensive than other photovoltaic systems. The goal of the present study was to design a disposable high-temperature transparent electrical insulating coating to cover metal plates for photovoltaic devices based on CZTS. The solution was to replace electrically conductive metallics dispersed in a high-temperature siloxane coating with phonon thermal conductivity ceramic particles. Properties of the obtained coating were investigated using different methods. A mathematical model of thermal processes in the film during heating was also developed. For the control sample and the sample with a heat-conducting filler, a quantitative ratio of thermal conductivity was obtained. The research results confirmed the necessary properties of the coating, including resistance to short-term exposure to high temperatures during the synthesis of kesterite.

Development of Siloxane Coating with Oxide Fillers for Kesteritic (CZTS) Photovoltaic Systems

The work focused on the development of high-temperature electrical insulation coatings for film photovoltaics. The idea was into replacing the electroconductive metal dispersed phase in siloxane high-temperature coating to ceramic particles with phonon thermal conductivity. The slurry of industrial composition based on polysiloxane lacquer and thermally conductive paste containing zinc oxide was centrifuged to obtain a thin, optically transparent coating with the destruction temperature of over 600 °C. Topology, electrical properties, and thermal conductivity of the resulting film were investigated. The mathematical model of thermal processes in films in the course of heating was figured out. Quantitatively the relation of thermal conductivities of a control sample and a sample with a heat-conducting filler was established. The effectiveness of using this technology is shown.

Синергический эффект гибридного наполнителя на основе графеновых нанопластин и многостенных нанотрубок для повышения теплопроводности эпоксидного композита

A hybrid heat-conducting filler based on graphene nanoplates and multi-walled nanotubes was obtained to increase the thermal conductivity of an epoxy binder, exhibiting a synergistic effect. This effect is achieved due to the embedding of multi-walled nanotubes between graphene nanoplates and the formation of effective percolation networks in the composite. The dependence of an increase in the thermal conductivity of an epoxy composite on the mass ratio of graphene nanoplates and multi-walled nanotubes in a mixture of a hybrid filler has been established. The effect of the hybrid filler concentration in the epoxy matrix and the mixing method of graphene nanoplates and multi-walled nanotubes on the thermal conductivity of the composite was found. A synergistic effect between graphene nanoplates and multi-walled nanotubes has been demonstrated, leading to a sixfold increase in the thermal conductivity of epoxy composites at a filler concentration of 5 wt%.

Synthesis, Electrical Conductivity, and Dielectric Behaviour of Nano Polyaniline doped with H2SO4; HCl and (HCl + NaNO2) mixture: A comparative study with acetone washing

Acid doped Polyaniline (PANI) due to their increased electrical conductivity, are considered to be the most promising conducting filler materials. Hence, the present study, reports the synthesis of the nano PANI followed by acid doping, electrical conductivity and dielectric properties measurements of H2SO4; HCl and (Conc. HCl + NaNO2mixture) doped PANI. In order to know the effect of acetone washing on the electrical properties of acid doped PANI samples, the electrical properties of the non-acetone washed acid doped PANI samples are compared with that of their acetone washed counterparts. The PANI salt was prepared by conventional route using aniline hydrochloride and ammonium persulphate as an oxidant. PANI salt was subjected to 0.5M NaOH to form PANI base, which was further doped separately with H2SO4; HCl and (Conc. HCl + NaNO2mixture) respectively followed by acetone washing. A comparative electrical conductivity study between the acetone washed and unwashed PANI salt and H2SO4, HCl and Conc. HCl + NaNO2 mixture doped PANI were characterized by dielectric and impedance study.

Biochar as a Conducting Filler to Enhance Electrical Conduction Monitoring for Concrete Structures

Smart and resilient concrete structures will require building materials such as cements that sense flaws. One mechanism of crack detection in structures is monitoring their electrical conduction. Two mechanisms of charge in cement is ionic movement and moisture diffusion. Carbon rich electrically-conducting char is produced by pyrolyzing rice husks and can be used to enhance electrical conduction in cement. This paper studies the evolution of electrical properties in ordinary Portland cement added with up to 15 wt% rice husk-derived biochar. Resistance of cements decreased with increasing biochar addition while moisture loss and resistance both increase as curing time increases. Cement with 15 wt% biochar experiences the largest moisture loss and the most conducting. This suggest charge transport along percolation paths of biochar particles is dominant mechanism in these materials. Electron microscopy and energy dispersive spectroscopic studies reveal formation of Ettringite phase and good wetting/bonding at the interface of biochar particles and cement.

Mechanically Enhanced Electrical Conductivity of Polydimethylsiloxane-Based Composites by a Hot Embossing Process

Electrically conductive polymer composites are in high demand for modern technologies, however, the intrinsic brittleness of conducting conjugated polymers and the moderate electrical conductivity of engineering polymer/carbon composites have highly constrained their applications. In this work, super high electrical conductive polymer composites were produced by a novel hot embossing design. The polydimethylsiloxane (PDMS) composites containing short carbon fiber (SCF) exhibited an electrical percolation threshold at 0.45 wt%, and reached a saturated electrical conductivity of 49 S/m at 8 wt% of SCF. When reduced the sample thickness from 1.0 mm to 0.1 mm by the hot embossing process, a compression-induced percolation threshold occurred at 0.3 wt%, while the electrical conductivity was further enhanced to 378 S/m at 8 wt% SCF. Furthermore, the additional of a second nanofiller of 1 wt%, such as carbon nanotube or conducting carbon black further increased the electrical conductivity of the PDMS/SCF (8 wt%) composites to 909 S/m and 657 S/m, respectively. The synergy of the densified conducting filler network by the mechanical compression and the hierarchical micro-/nanoscale filler approach has realize super high electrical conductive yet mechanical flexible polymer composites for modern flexible electronics applications.