Ksenia Parkhomenko

Ambipolar organic transistors and near-infrared phototransistors based on a solution-processable squarilium dye†

Implementation of organic transistors in low-end, large-volume microelectronics depends, greatly, on the level of performance that can be achieved, but also on the compatibility of the technology with low-cost processing methodologies. Here we examine the suitability of a family of solution-processable zwitterionic molecules, so-called squarilium dyes, for the fabrication of organic ambipolar transistors and their application in (opto)electronic circuits. Ambipolar organic semiconductors and transistors are interesting because they could deliver performance characteristics (i.e. noise margins and signal gain) similar to that of complementary logic, but with the fabrication simplicity associated with unipolar logic (i.e. single semiconductor material and single type of metal electrodes). By designing squarilium dyes with appropriate electrochemical characteristics we demonstrate single-layer organic transistors that exhibit ambipolar charge transport with balanced electron and hole mobilities. By integrating a number of these ambipolar transistors we are also able to demonstrate complementary-like voltage inverters with wide noise margin and high signal gain. Another interesting feature of the squarilium dyes studied here is their strong absorption in the near-infrared (NIR) region of the electromagnetic spectrum. By exploring this interesting property we are able to demonstrate NIR light-sensing ambipolar organic transistors with promising operating characteristics.

Specifics of phase transformations in Li/W/Mn/SiO2 composites at influence of methane-oxygen and hydrogen-air mixtures

Li/W/Mn/SiO2 composites were studied immediately after sol-gel or solid-phase synthesis and the high-temperature exposure to methane-oxygen and hydrogen-air mixtures. The phase compositions of these catalysts, which determines their catalytic activities in the oxidative coupling of methane, were shown to depend on the method of synthesis, the ratio of cations, and the composition of the submitted gas mixture.

Effect of the nature of promoters, the alkaline treatment of ZSM-5 zeolites, and the method of their synthesis on the conversion of C3–C4 alkanes

The zinc and chromium copromotion of an industrial ZSM-5 zeolite and its structural analogues synthesized under laboratorial conditions by the hydrothermal and microwave-assisted hydrothermal methods increases the selectivity towards the formation of aromatics from a mixture of C3-C4 alkanes. The formation of additional mesopores in the structure of ZSM-5 also improves the selectivity to aromatic hydrocarbons.

Neodymium-calcium cobaltates: Features of synthesis, phase composition, activity and selectivity in partial methane oxidation

Nd2 − xCaxCoO4 ± δ-based materials demonstrated high effectiveness in partial methane oxidation into synthesis gas with almost 100% selectivity. It has been determined that Nd2 − xCaxCoO4 ± δ materials synthesized via the solid-state or cryochemical methods are single-phase in the range of 0.6 ≤ x ≤ 1 at a synthesis temperatures of 1100–1200°C. Synthesis at t ≤ 1100°C allows to prepare solid solutions in the range of 0.9 < x < 1.05.

Ni and Rh containing mesoporous amorphous silicate catalysts for dry reforming of methane

T UD-1 mesoporous silicate materials with incorporated Ni and Rh were prepared by sol-gel one-pot synthesis. The catalytic performance of synthesized materials in dry reforming of methane was compared as well as the stability in time-on-stream experiments. These materials with directly incorporated active metals allowed remarkable increasing of CH 4 and C O2 conversions up to 92 % and 95 %, respectively. Ni-TUD-1 catalyst provided very low c arbon deposition together with the excellent stability over 50 h. The effect of Rh addition was evaluated.