The Shockley-Queisser (SQ) limit for a single junction solar cell is ~33.5 (under the standard AM1.5 flat-plate, solar spectrum).  Indeed detailed calculations show that GaAs is capable of achieving this efficiency. Nonetheless, the record GaAs solar cell had achieved only 26.4% efficiency in 2010.  Previously, the record had been stuck at 25.1% for almost two decades.  Why then the 7% discrepancy between the theoretical limit 33.4% versus the achieved efficiency of 26.4%?

Energy and water are precious, global, and interconnected resources. Water provides hydroelectric power and plays a growing role for irrigation of energy crops. At the same time, the thermoelectric sector is the largest user of water in the U.S., withdrawing 200 billion gallons daily for powerplant cooling. And while the energy sector uses water, the water sector is responsible for about ten percent of national energy consumption for moving, pumping, treating, and heating water.

Graphene, a unique two-dimensional carbon material, has many excellent properties, such  [HuiMing Cheng] as high specific surface area, good chemical stability, ultrahigh mobility, high electrical and thermal conductivity, as well as high mechanical strength and Young’s modulus. Therefore, graphene and its composite materials are expected to be used in many fields. This talk will focus on the synthesis and exploration of applications of graphene, graphene networks and their composite materials.

The Berkeley "Par Lab" was established in 2008 to address perhaps the greatest ever challenge in computing systems: the end of sequential processor performance scaling and the resultant need to move to parallel computing everywhere. Our ambitious goal is “to enable most programmers to productively write correct, portable, efficient software for manycore processors that will scale with the number of cores”. We formed a large co-located team of faculty and students collaborating to tackle this problem from applications down to architecture.

Scale-out architectures supporting flexible, incremental growth in capacity are common for computing and storage. However, the network remains the last bastion of the traditional scale-up approach, where increasing performance requires increasing levels of specialization at tremendous cost and complexity. Today, the network is often the weak link in data center application performance and reliability. In this talk, we summarize our work in bringing scale out growth of capacity to data center networks.

This talk will dicuss the chirp managed laser (CML), an alternative transmitter technology that allows a directly modulated laser to be used in high performance applications with a smaller size, lower power consumption, less device complexity and lower cost.  The CML comprises a directly modulated laser and an isolated passive optical filter, and can have lower power consumption than externally modulated transmitters.

Lithium-ion batteries (LIB) have been used as a power source for mobile electronic devices such as notebook PCs and cellular phones since they were introduced into the market in 1991.  Recently, they have been attracting attention as a power source for automobiles and energy storage devices for sustainable energy resources such as solar and wind power, which are key technologies in solving global warming and energy security problems.  Market demands have caused a change in the active materials used in lithium batteries, which in turn has forced a change in the electrolyte material

While the auto industry continues to make incremental progress toward competitive electric vehicles, we pose a strategic question: can we effect disruptive change in the economics of electric vehicles by improving the systems-level interaction of a vehicle with each unique commuter?  This talk will motivate and describe ChargeCar, a new CREATE Lab project that combines direct community engagement with a hybrid supercapacitor-battery energy management system to increase EV efficiency while decreasing battery duty.

The III-N materials system has many material properties which make it an excellent candidate for high efficiency PV cells, and as such InGaN-Ns have begun to gain attention for use in photovoltaic (PV) devices. The band gap of InN was recently discovered to be 0.7 eV as opposed to the previously believed 1.3 eV. The importance of this discovery is that the band gap of the InGaN material system spans nearly the entire solar spectrum (0.7 eV – 3.4 eV) thus enabling design of multijunction solar cell structures with near ideal bandgap energies for maximum efficiency.

Photovoltaics research represents one of the greatest opportunities to impact the climate change and energy security problems that we face today. Over 1.5×10^22 J (15,000 EJ) of solar energy reach Earth everyday, compared to a daily energy consumption of approximately 1.3 EJ by human activity. The potential for new 4-, 5-, and 6-junction solar cell architectures, capable of greater than 70% efficiency in theory, to reach practical efficiencies over 50% is highly leveraging for the economics of concentrator photovoltaic (CPV) systems.