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The development of molecular semiconductors for optoelectronic devices has tremendous impact on energy production. However, a major challenge to attain widespread implementation of this technology would be to develop materials by cost effective methods and achieve high stability. Although this can pose a great challenge, the concept of bulk heterojunction has provided the record breaking efficiency of as high as 9.2%. However, a clear relationship between the material properties and stability is still lacking. In this talk, the role of torsional defects in molecular semiconductor shall be discussed. Moreover, our recent results of ambipolar molecular semiconductors for organic field-effect transistors (OFET) will be highlighted.

References:
1) Influence of Side-Chain on Structural Order and Photophysical Properties in Thiophene Based Diketopyrrolopyrroles: A Systematic Study, Mallari A. Naik, N. Venkatramaiah, Catherine Kanimozhi, and Satish Patil*, Journal of Physical Chemistry-C, 2012, 116, 26128–26137

2) Diketopyrrolopyrrole-Diketopyrrolopyrrole-Based Conjugated Copolymer for High-Mobility Organic Field-Effect Transistors, Kanimozhi, C.; Yaacobi-Gross, N.; Chou, K. W.; Amassian, A.; Anthopoulos, T. D.; Satish Patil, J. Am. Chem. Soc. 2012, 134, 16532

The longstanding reliance on fossil fuels as the principal energy source for society has boosted the atmospheric CO2 concentration to a level that is unprecedented in modern geological history. Since the use of carbon-containing fuels is entrenched in society, controlling the atmospheric CO2 concentration may ultimately require recycling CO2 into liquid fuels and commodity chemicals using renewable energy inputs. Arguably the greatest challenge for this vision is to develop efficient CO2 reduction catalysts. This talk will describe our recent development of “oxide-derived” metal nanoparticles as electroreduction catalysts. Oxide-derived metal nanoparticles are prepared by electrochemically reducing metal oxide precursors. This procedure results in highly strained metal nanocrystals. I will describe examples of these catalysts that electrochemically reduce CO2 to CO with exceptional energetic efficiency as well as a catalyst that selectively reduces CO to two-carbon oxygenates. The mechanisms of CO2 and CO reduction will be discussed based on electrokinetic measurements. Metal oxide reduction represents a “top-down” approach to metal nanoparticle synthesis that can result in unique surface structures for catalysis.

The mechanism of nanostructuring by pulsed femtosecond laser-based illumination of scanning probe tips was examined in respect to optical-near-field effects. Apertureless near-field scanning force probes at sufficiently high intensities of ns laser and fs laser irradiation can deliver morphological and structural changes in materials at the nanometric level. The SFM tip plasmon response leads to a significant local field enhancement between the tip and substrate. This study is concerned with optical-field enhancement and confinement for an asymmetrically illuminated nanoscopic SFM tip suspended over different materials like gold, graphene, polyphenylen-oxide or polycarbonate according to an apertureless scanning nearfield optical microscope (a-SNOM)

The Gulf of Eilat is an elongated, deep basin in the northern Red Sea. We investigate various mixing processes using recent observational data acquired from a combination of moored platforms and HF coastal radar. We present the first regular ,high vertical resolution profiles of density and velocity and the first deep, long-term profiles of velocity and high frequency temperature measurements collected in the Gulf of Eilat.
> The variability of the stratification and its effect on the magnitude of alongshore semi-diurnal tidal currents in the northern Gulf of Eilat/Aqaba are examined using recent observational data acquired from a combination of moored platforms. The variability of the stratification consists of both periodic and episodic components and occurs over a range of time scales, from hourly to seasonal. Large amplitude, tidally-driven internal waves were observed throughout the year under different stratification conditions. Episodic cooling and warming events were observed during convective mixing in winter and re-stratification in spring. The magnitude of the alongshore semi-diurnal tidal currents is strongly correlated with the stratification.
> Lateral mixing is examined using surface current measured by HF radar. Here, we modify the traditional random-walk stochastic model to include a large-scale flow (obtained from a numerical model, satellite measurements, or HF radar surface current measurements) that varies in both space and time. A stochastic term is added to represent sub-grid-scale, or unresolved, turbulence and is related to the horizontal eddy diffusivity and thousands of virtual particles are transported by the large-scale flow and the stochastic "jumps." The magnitude of the eddy diffusivity is increased until the barrier is no longer present in the flow field, thus providing an estimate of the upper bound of the horizontal eddy diffusivity.