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Archive for May, 2013

Splitting One Photon to Two Electrons: Toward Breaking the Single Junction Efficiency Limit

Wednesday, May 15th, 2013

jiye leeTuesday July 9, 2013
Noon – 1  pm
Texas Instruments (TI) Auditorium E-1
2900 Semiconductor Drive
Santa Clara, CA
map

TITLE: Splitting One Photon to Two Electrons: Toward Breaking the Single Junction Efficiency Limit

SPEAKER: Dr. Jiye Lee, Postdoctoral fellow in the Molecular Foundry at LBNL

 

ABSTRACT:
Conventional solar cells generate one electron for each absorbed photon. Any excess photon energy above the bandgap is wasted as heat. This fundamental energy loss imposes the Shockley-Queisser limit of 34% for single optimized semiconductor junction. Singlet fission, a nanoscale process in organic molecules, splits a high-energy molecular excitation into a pair of low-energy ones. In solar cells, it promises to double the electricity generated from the blue part of the sunlight, breaking the single junction efficiency limit.

I will present fission-based photovoltaic cells that produce more than one electron per photon. This is the first time that any solar cell has shown the peak photon-to-electron conversion efficiency exceeding 100% in the visible spectrum. To further advance fission-enhanced solar cell nanotechnology, it is crucial to understand the fundamental mechanism governing singlet fission. I will report on a universal mechanism that predicts the rate of singlet fission and confirm that fission is robust to variations in molecular nano-morphology.

SPEAKER BIOGRAPHY:
Jiye Lee is currently a postdoctoral fellow in the Molecular Foundry at Lawrence Berkeley National Laboratory. She received her PhD in electrical engineering from MIT. Her PhD thesis won the Microsystems Technology Laboratories Doctoral Dissertation Seminar at MIT. She obtained her B.S. in electrical engineering from KAIST in South Korea in 2006. She spent a summer in 2011 at Palo Alto Research Center.Her research interests are optoelectronics and photovoltaics based on nanomaterials, including organic molecules.

AGENDA:

  • 11:30 am – Registration & light lunch (pizza & drinks)
  • Noon – Presentation & Questions/Answers
  • 1:00 pm - Adjourn
COST: IEEE Members: $5, Non-members:$10


 

Energy Harvesting from Waste Heat and Sun Light with Mesoscopic Materials

Wednesday, May 15th, 2013

Nobuhiko P. KobayashiTuesday June 18, 2013
Noon – 1  pm
Texas Instruments (TI) Auditorium E-1
2900 Semiconductor Drive
Santa Clara, CA
map

TITLE: Energy Harvesting from Waste Heat and Sun Light with Mesoscopic Materials

SPEAKER: Prof. Nobuhiko P. Kobayashi, Dept. of Electrical Engineering, UC Santa Cruz

 

ABSTRACT:
Designing solid-state devices is essentially restricted by choosing available chemical elements found on the Periodic Table and forming various stable solids made of these chemical elements. A key to developing novel solid-state devices is, therefore to find a route to combine a variety of such solids often physically and/or chemically incompatible each other to benefit from resulting combined material platforms. In this talk, specific examples of “Mesoscopic Materials” will be presented with the view toward solid-state devices for energy harvesting from waste heat and sun light. The talk is divided into the following two sections.
1. Semiconductor nanocomposites for energy harvesting from waste heat: thermoelectric.
2. Metal oxide thin films for high-power solar energy collection and transmission: Sun to fiber.

SPEAKER BIOGRAPHY:
Nobuhiko “Nobby” P. Kobayashi is a professor at the University of California Santa Cruz (UCSC) and the Science Director of Advanced Studies Laboratories, a strategic partnership between UCSC and NASA Ames Research Center. Current research projects include synthesis and characterization of nanometer-scale materials and devices with emphasis on solid-state energy conversion funded by DARPA, ONR, NSF, NASA, DOE, SRC, and ARPA-E. Prior to joining UCSC in 2008, Prof. Kobayashi was involved in developing electronic materials for memristive devices to build memories and logics required for future computing systems at Hewlett-Packard Laboratories. He also led semiconductor nanowire photonics for optical interconnect necessary for advanced computing systems. Prior to Hewlett-Packard Laboratories, Prof. Kobayashi worked at Lawrence Livermore National Laboratory, where he was involved in developing semiconductor materials for both ultra-high speed diagnosis systems required for the National Ignition Facility and the optical code division multiple access funded by DARPA. From 1999 to 2001, Prof. Kobayashi was at Agilent Laboratories, developing light emitting diodes, vertical cavity surface emitting lasers, and hetero bipolar transistors for ultra-wide band fiber-optics and high-speed wireless communications. Prof. Kobayashi earned his M.S. and Ph.D. degrees in materials science from University of Southern California in 1994 and 1998.

AGENDA:

  • 11:30 am – Registration & light lunch (pizza & drinks)
  • Noon – Presentation & Questions/Answers
  • 1:00 pm - Adjourn
COST: IEEE Members: $5, Non-members:$10