Group-III nitrides are the key materials for light-emitting diodes in the blue part of the visible spectrum, which are the basis for high-efficiency solid-state general lighting. A large research effort is aimed at extending this success to the green and the yellow range, where nitride LEDs are significantly less efficient. Though it has been noted that the efficiency of III-nitride devices may be limited by Shockley-Read-Hall recombination at point defects, the microscopic mechanism and defects responsible are unknown.

Conjugated polymers provide a unique encompassing set of structurally tunable optical, electronic transport, and redox properties that allows their present and potential use in a host of applications which span, field effect transistors, light emitting diodes, solar cells and photodetectors, electrochromism, along with batteries and supercapacitors.  Processing of these materials is carried out using a variety of solution methods including spin-coating, spray-coating, blade-coating, slot die coating and ink jet printing.  In this lecture, we will use the reversible redox switching

The US International Space Station National Laboratory is a Low Earth Orbit (LEO) platform for conducting research that requires the unique conditions in space.   Long-duration microgravity, vantage point for earth observation, and the extreme space environment are valuable for a broad range of investigations in the life and physical sciences.  CASIS is a non-profit entity established in 2011 through an act of Congress to manage 50% of the ISS NL in a cooperative agreement with NASA with the purpose of maximizing outcomes benefiting earth.  This talk will describe some o

Integrated photonic devices have traditionally been designed for data communications using exclusively solid-state materials. However, a vast area of potential applications, in particular in the life sciences, involve interactions of light with liquids and gases. Recently, a number of optofluidic approaches have been considered that are aimed at integrating such non-solid media with chip-scale photonic structures. We have developed a versatile, planar photonic platform based on hollow-core optical waveguides (ARROWs).

Wind turbines are often deployed in arrays of hundreds of units, where wake interactions can lead to drastic losses in power output. Remarkably, while the theoretical “Betz” maximum has long been established for the output of a single turbine, no corresponding theory appears to exist for a generic, large-scale energy extraction system. We develop a model for an array of energy-extracting devices of arbitrary design and layout, first focusing on the fully-developed regime, which is relevant for large wind farms.

Many organic and hybrid thin film electronic devices (e.g. memory diodes, solar cells, light emitting diodes, transistors, capacitors) typically contain a functional layer based on a blend comprising multiple polymeric or small-molecular species whose properties cooperatively give rise to a specific function. Depending on the desired functionality, phase separation during film processing is either encouraged or suppressed. As usually at least one blend component is polymeric, mutual segmental repulsion readily overcomes the entropic driving force to form stable mixtures.

The aggregation of p-conjugated materials significantly impacts on the photophysics, and thus on the performance of optoelectronic devices. Nevertheless, we know comparatively little about the laws governing aggregate formation of p-conjugated materials from solution. In this talk, I shall compare, discuss and summarize how aggregates form for three different types of compounds, that is, homopolymers, donor-acceptor type polymers and low molecular weight compounds.

The Center for Nanoinetgration Duisburg-Essen (CENIDE) is a research center that focuses on nanoscience as the main research area of the University of Duisburg-Essen (UDE, Germany). Since 2005, CENIDE links the activities in natural science, engineering and medicine at the UDE that deal with the nano dimension.

Integrating high-performance III-V devices on the mature silicon platform has been a long pursuit over the past few decades. Direct epitaxial growth offers an alternative technology to bonding.  Using nano-patterned Si substrates, we created III-V on silicon templates with low defect density and smooth surface morphology for laser growth.  Such antiphase-domain (APD)-free III-V on silicon compliant templates with high crystalline quality (benchmarked by narrow XRD halfwidths) are grown without the need of special off-cut substrates and/or Ge buffer.

Mobile computing is experiencing a technological renaissance, and the Web is Florence. Throughout the past decade, the Web has redefined the way people retrieve information, communicate with one another, and extract insights. Although rife with opportunity, the energy-constrained nature of mobile devices is a major roadblock to the potential that next-generation Web technologies promise.