End-of-Waste SiC-Based Flexible Substrates with Tunable Electrical Properties for Electronic Applications

We demonstrated the suitability of polymer composites filled with silicon carbide (SiC) powders derived from a recycling process for applications in electronic devices manufacturing. SiC powders have been synthesized from the process byproducts and used as fillers in the formulation of polystyrene (PS)/SiC composites, which have been used in the preparation of substrates using the solution-casting technique. Different substrates have been prepared by changing the concentration of SiC in the composite in the range from 6.7 to 67 wt % and used in simple electronic devices by performing gold contacts in both planar and stacked configurations. The electrical behaviors of both stacked and planar devices were investigated in direct current (DC) and alternate current (AC) regimes. The experimental results showed that charge percolation could be considered an explanation for the abrupt change in the differential conductivity observed around 30 wt %. Fowler–Nordheim tunneling at high fields has been found to be compatible with static characteristics and with high-frequency AC measurements and, therefore, charge tunneling between SiC islands has been proposed as the physical mechanism provoking the changes in charge transport in the substrates investigated. From this first experimental analysis, it appears that SiC/PS composites could suit their use in tunneling-gate dielectrics (i.e., in transistors suitable for their applications in nonvolatile random-access memory) for low concentrations or as a continuous semiconducting media when SiC is dispersed in high-concentration composites

Fabrication of Novel Two-Dimensional Nanopatterned Conductive PEDOT:PSS Films for Organic Optoelectronic Applications

This paper presents a novel strategy to fabricate two-dimensional poly­(3,4 ethylenedioxythiophene):poly­(styrene sulfonate) (PEDOT:PSS) photonic crystals (PCs) combining electron beam lithography (EBL) and plasma etching (PE) processes. The surface morphology of PEDOT:PSS PCs after mild oxygen plasma treatment was investigated by scanning electron microscopy. The effects on light extraction are studied experimentally. Vertical extraction of light was found to be strongly dependent on the geometric parameters of the PCs. By changing the lattice type from triangular to square and the geometrical parameters of the photonic structures, the resonance peak could be tuned from a narrow blue emission at 445 nm up to a green emission at 525 nm with a full width at half-maximum of 20 nm, which is in good agreement with Bragg’s diffraction theory and free photon band structure. Both finite-difference time-domain and plane wave expansion methods are used to calculate the resonant frequencies and the photonic band structures in the two-dimensional photonic crystals showing a very good agreement with the experiment results. A 2D nanopatterned transparent anode was also fabricated onto a flexible polyethylene terephthalate (PET) substrate and it was integrated into an organic light-emitting diode (OLED). The obtained results fully confirm the feasibility of the developed process of micro/nano patterning PEDOT:PSS. Engineered polymer electrodes prepared by this unique method are useful in a wide variety of high-performance flexible organic optoelectronics