APPLICATIONS OF TECHNOLOGY:

Fabrication of energy-efficient and cost-efficient devices including

• Organic-nanomaterial hybrid solar cells
• Optoelectronic devices, such as light-emitting diodes (LEDs) and nanolasers
• Light collectors

ADVANTAGES:

• Allows more controlled solar cell design
• Improves efficiency of previous polymer-based solar cells
• Lowers fabrication costs
• Tunable composition of materials and optoelectronic properties

ABSTRACT:

Organic, polymer-based solar cells--lightweight alternatives to conventional, silicon-based solar cells--have great potential for delivering inexpensive solar energy and lowering manufacturing costs while maintaining high power efficiency. However, the highest efficiency achieved so far with polymer-based solar cells is only 5% to 6%, far too low to be effective in many applications. In addition, the synthesis of these solar cells is controlled only by temperature and mixing times; yet neither factor adequately controls the structure of nanofeatures, such as conductive channels, that play a significant role in solar cell performance.

By controlling the molecular shape, structure, and pattern of the materials in organic, polymer-based solar cells, Alex Zettl and Jeffrey Grossman of Berkeley Lab have developed a technique that improves power efficiencies by a factor of two. The new method provides a way to make affordable, high-performance, polymer-based solar cells as well as optoelectronic devices (LEDs, nanolasers) and light collectors.  

To ensure that conductive channels are grown in the direction most suitable for efficient charge extraction, magnetic or electric fields are used to align magnetically-doped semiconductor nanoparticles as they are blended with photovoltaic materials. This creates a well-controlled interface or connection between the solar cell's components and overcomes a common hurdle in standard polymer-based solar cells--the internal loss of electronic charges before they can usefully exit the device. As a result, photons can be more efficiently absorbed and converted to energy.

In addition to making more affordable, power-efficient polymeric solar cell devices, the new method can be used to customize materials for any photovoltaic or optoelectronic device.   The light absorption spectrum of the device's photoactive layer, which contains an electron-donor material and an electron-acceptor material, can be adjusted, depending upon the composition and/or size of the polymer nanocrystals making it more versatile than solar cell fabrication methods currently in use.

STATUS:

• Published Patent Application PCT/US2009/058549 available at www.wipo.int. Available for licensing or collaborative research.

To learn more about licensing a technology from LBNL see http://www.lbl.gov/Tech-Transfer/licensing/index.html.

REFERENCE NUMBER: IB-2365

SEE THESE OTHER BERKELEY LAB TECHNOLOGIES IN THIS FIELD:

• Ideal Configuration for Nanoscale Solar Cells, IB-2364
• High Efficiency, Self-Concentrating Nanoscale Solar Cell, IB-2338
• Low Cost, High Efficiency Tandem Silicon Solar Cells, IB-2357
• Streamlined Synthesis of Binary Nanorods for Power-Efficient Nanocrystal Devices, IB-2490