CEEM Final Technical Report [electronic resource].
- Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2014.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
- Physical Description:
- 15 pages : digital, PDF file
- Additional Creators:
- University of California, Santa Barbara
United States. Department of Energy. Office of Basic Energy Sciences
United States. Department of Energy. Office of Scientific and Technical Information
- The mission of the Center for Energy Efficient Materials (CEEM) was to serve the Department of Energy and the nation as a center of excellence dedicated to advancing basic research in nano-structured materials and devices for applications to solar electricity, thermoelectric conversion of waste heat to electricity, and solidstate lighting. The foundation of CEEM was based on the unique capabilities of UCSB and its partner institutions to control, synthesize, characterize, model, and apply materials at the nanoscale for more efficient sustainable energy resources. This unique expertise was a key source of the synergy that unified the research of the Center. Although the Center’s focus was basic research, It’s longer-term objective has been to transfer new materials and devices into the commercial sector where they will have a substantial impact on the nation’s need for efficient sustainable energy resources. As one measure of the impact of the Center, two start-up companies were formed based on its research. In addition, Center participants published a total of 210 archival journal articles, of which 51 were exclusively sponsored by the DOE grant. The work of the Center was structured around four specific tasks: Organic Solar Cells, Solid-State Lighting, Thermoelectrics, and High Efficiency Multi-junction Photovoltaic devices. A brief summary of each follows – detailed descriptions are in Sections 4 & 5 of this report. Research supported through CEEM led to an important shift with respect to the choice of materials used for the fabrication of solution deposited organic solar cells. Solution deposition opens the opportunity to manufacture solar cells via economically-viable high throughput tools, such as roll to roll printing. Prior to CEEM, most organic semiconductors utilized for this purpose involved polymeric materials, which, although they can form thin films reliably, suffer from batch to batch variations due to the statistical nature of the chemical reactions that produce them. In response, the CEEM team developed well-defined molecular semiconductors that produce active layers with very high power conversion efficiencies, in other words they can convert a very high fraction of sunlight into useful electrical power. The fact that the semiconductor is formed from molecular species provides the basis for circumventing the unreliability of polymer counterparts and, as an additional bonus, allows one to attain much grater insight into the structure of the active layer. The latter is particularly important because efficient conversion is the result of a complex arrangement of two semiconductors that need to phase separate in a way akin to oil and water, but with domains that are described by nanoscale dimensions. CEEM was therefore able to provide deep insight into the influence of nanostructure, through the application of structural characterization tools and theoretical methods that describe how electrical charges migrate through the organic layer. Our research in light emitting diode (LED)-based solid state lighting (SSL) was directed at improving efficiency and reducing costs to enable the widespread deployment of economically-viable replacements for inefficient incandescent, halogen, and fluorescent-based lighting. Our specific focus was to advance the fundamental science and technology of light emitting diodes to both understand factors that limit efficiencies and to provide innovative and viable solutions to the current impediments. One of the main challenges we faced is the decrease in efficiency when LEDs are driven harder to increase light output---the so called “droop” effect. It requires large emitting surfaces to reach a desired optical output, and necessitates the use of costly heat sinks, both of which increase the cost. We successfully reduced droop by growing LED crystals having non-conventional orientations. As recognized by the award of the 2014 Nobel prize to the inventors of the nitride LEDs (one of who...
- Published through SciTech Connect.
- Type of Report and Period Covered Note:
- Funding Information:
View MARC record | catkey: 23760444