Research: Next-Generation Photovoltaic Technologies

Creating ideal structures for photovoltaics using block copolymers

One of the key factors determining the efficiency of organic and hybrid solar cells is their structure on the nanoscale. This structure determines factors such as how well the electron-hole pairs are separated and whether there are direct pathways for the separated charges to find their way to the electrodes. Typical devices are comprised of randomly arranged electron-donating and electron-accepting semiconductors where processing conditions are employed to try and engineer the optimal nanostructure. In order to better understand the relationship between structure and photovoltaic properties, a team at Argonne is utilizing a class of materials called block copolymers. Block copolymers are long-chain molecules comprised of two (or more) different segments having different properties. These materials can assemble themselves into highly ordered structures that can be designed with great flexibility. By systematically varying structural parameters and monitoring their influence on properties such as charge separation and transport, the team hopes to provide new insights into how these next-generation devices operate and, ultimately, to improve their performance.

Block copolymers can self-assemble into highly ordered structures that enable detailed studies of structure-property relationships in organic and hybrid solar cells.

References

• Energy Environ. Sci. 2 (2009) 1266
• Macromolecules 42 (2009) 8211
• Langmuir 26 (2010) 8756
• Materials Today 13 (2010) 42

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March 2010