Semiconducting nanostructures offer potentially revolutionary advancements in the cost and performance of light emitting diodes for solid state lighting and photovoltaic energy converters. GaN based LEDs are usually fabricated on expensive substrates and suffer from a high density of threading dislocations. In addition, the high current performance of the devices is degraded by efficiency decreases (efficiency droop) that seem to be inherent to current designs.

Organic photovoltaic devices (OPVs), that utilize organic small molecules and/or polymers to directly convert sunlight to electricity, are an attractive technology for sustainable, low cost, clean energy production.  For example, solution-processed bulk heterojunction (BHJ) OPVs have attracted much attention because of their potential for flexible, light-weight, large area and low-cost device fabrication.  In particular, fullerene compounds have been the dominating electron acceptor/transport material in BHJ OPVs.  However, fullerene compounds have some disadvantages, such as

Awarded annually, the lectureship is considered the highest honor bestowed by the university faculty on one of its members. Bowers is the 58th recipient of the award. His lecture, titled “The Promise of Silicon Photonics,” is free and open to the public. A reception will follow.

Technology scaling has provided enormous growth opportunities for the information and communication industry over the last few decades. It enables faster and cheaper products that deeply touch people’s life. Technology scaling is also crucial in improving energy efficiency, a hot topic lately as users demand ubiquitous computing and communications with minimum impact to the environment. In this presentation I will highlight research at Intel Labs spanning circuits, architecture, and platform to scale technology for energy efficiency.

Recent advances from two diametric approaches for realistically approaching the fundamental limits to solar cell conversion efficiency, which follow from basic thermodynamics, will be presented. One relates to a new concept in cell architecture for concentrator photovoltaics, with the possibility of using exclusively indirect bandgap semiconductors (including Si and Ge) at irradiance values of thousands of suns. The second constitutes the first experimental demonstration of performance enhancement by recycling photon emission from high-efficiency non-concentrator (one-sun) solar cells.

Limit Cycle oscillators are used to model a broad range of periodic nonlinear phenomena. Using the Optically Injected Semiconductor Oscillator as a paradigm, we will demonstrate that at specific islands in the detuning and injection level map, the period-one oscillation frequency is simultaneously insensitive to multiple perturbation sources. In our system these include the temperature fluctuations experienced by the master and slave lasers as well as fluctuations in the bias current applied to the slave laser.

In this talk I will re-examine several key, assumed boundary conditions used in designing organic solar cells, and discuss novel device structures and thin film deposition techniques that can help circumvent a number of performance limiting factors. These include parasitic exciton quenching near electrodes, bulk recombination, and charge transport limitations.

Metallic nanoparticles support strong, localized oscillations of conduction electrons – surface plasmons  – that have recently enabled significant improvements in photovoltaic and photocatalytic cell efficiencies. While considerable research has investigated the potential for somewhat larger plasmonic particles (>20 nm) to enhance solar energy conversion, most catalytic reactions rely on the high catalytic activity of very small metallic particles.

Despite the incredible market penetration of smartphones and exponential growth of the app market, utility of smartphones has been and will remain severely limited by the battery life. As such, energy has increasingly become the scarcest resource on smartphones which critically affects user experience. In this talk, I will start with a first study that characterizes smartphone energy bugs, or ebugs, broadly defined as an error in the smartphone system (apps, framework, OS, hardware) that results in unexpected smartphone battery drainage and leads to significant user frustration.

Power has become a first-class design constraint in computing platforms from the smartphone in your pocket to warehouse-scale computers in the cloud.  Historically, semiconductor innovation has repeatedly provided more transistors (Moore’s Law) for roughly constant power per chip by scaling down supply voltage each generation.  Unfortunately voltage scaling has ended due to stability limits and chip power densities are increasing each generation on a trajectory that outstrips improvements in the ability to dissipate heat.