Read this Review article by Michael Krüger and colleagues.
Recent development of bulk-heterojunction hybrid solar cells is reviewed and strategies for further improvement are discussed:
Bulk-heterojunction hybrid solar cells based on colloidal nanocrystals and conjugated polymers
Yunfei Zhou, Michael Eck and Michael Krüger
Energy Environ. Sci., 2010,DOI: 10.1039/C0EE00143K