Tuning of electron tunneling: a case study using BODIPY molecular layers.

Redox active π-conjugated organic molecules have shown the potential to be used as electronic components such as diode and memory elements. Here, we demonstrate that using simple surface chemistry, rectification characteristics can be tuned to reproducible negative differential resistance (NDR) with a very high peak-to-valley ratio (PVR) up to 1000 in 2,6-diethyl-4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indecene (BODIPY) grafted on Si. The change in properties is related to oxidation and reduction of BODIPY, which results in the change in resonant to non-resonant tunneling of electrons under bias. This has been explained by the ab initio molecular-orbital theoretical calculations.

One pot, single step, room temperature dielectrophoretic deposition of gold nanoparticles clusters on polyethylene terephthalate substrate.

The major challenge of plastic electronics is the deposition of gold nanoparticles (AuNPs) on flexible substrates at room temperature. Here, we show fast, single step, room temperature deposition of AuNPs on polyethylene terephthalate (PET) and biaxially oriented PET (BoPET) substrate by employing dielectrophoresis. The deposition has been carried out using two-electrode system, with BoPET (or PET) and metallic (Pt or stain steel) mesh, under an AC signal of 20 kHz and 20 V peak-to-peak (V(pp)) (signal for PET is 6 V(pp) and 6 kHz). In this method, we show how to deposit AuNPs on PET-like insulator by exploiting its polarization capability under an AC signal. The polarization of PET has been confirmed by change in the Raman spectra of the PET film under in situ AC signals. Furthermore, we show that using this dielectrophoretic deposition method, the PET films can be patterned by AuNPs at room temperature without any pre- and posttreatment.

A strategy towards the synthesis of superhydrophobic/superoleophilic non-fluorinated polypyrrole nanotubes for oil-water separation.

Superhydrophobic/superoleophilic materials have shown great potential for applications in oil/water separation. However, practical applications of these materials are restricted due to their toxicity and complicated, expensive, and non-eco-friendly fabrication procedures. Here, we have successfully developed an easy, simple, cost-effective, and environmentally friendly strategy towards the synthesis of superhydrophobic and superoleophilic porous polypyrrole nanotubes. Such wettability has been introduced into polypyrrole by co-doping with sodium dodecylbenzenesulfonate, a surfactant for lowering surface energy and controlling the morphology of the nanotubes. These non toxic and environment friendly polymer nanotubes exhibit oil absorption capability from oil/water mixtures with a reasonable efficiency with good reusability.