2008-662 Improved Photovoltaic Efficiency in Semiconducting Polymer/fullerene Solar Cells through Control of Fullerene Self-assembly and Stacking

Summary

Researchers at UCLA have developed a method for increasing the efficiency of polymeric/organic solar cells based on fullerenes and fullerene derivatives that utilize self-assembly to achieve very dense networks.

Background

Polymeric solar cells based on fullerene and fullerene derivatives are a clean, renewable, and cheap energy source, however the efficiency does not yet rival that of silicon-based technologies. Previous work to increase the efficiency of these polymeric/organic solar cells focused on increasing the density of active material in the device area. This has previously been accomplished by enhancing the solubility of the fullerene molecules and subjecting the devices to thermal annealing. Both of these techniques lead to improved efficiency by controlling the arrangement of the molecules to provide better packing, yet neither completely solves the problem.

Innovation

Researchers at UCLA have identified a self-assembly method for arranging fullerene molecules that results in a 4X increase in solar cell energy conversion efficiency (current density; on average). This technique allows more control over the packing of individual molecules to provide for higher material densities that result in the improved efficiency.

Applications

• Improving efficiency in polymeric/organic solar cells
• Also applicable to polymeric/organic photodetectors, diodes, and FETs

Advantages

• Allows precise control over the morphology of the blended active layer
• Solution-based processing method with associated manufacturing cost advantages
• Compatible with other efficiency improving process

State of Development

Solar cells have been manufactured and demonstrate improved performance.