Excitonic photovoltaic effect in a cyanine dye molecular assembly electronically coupled to n- and p-type semiconductors

• J-aggregated dye film with ends bonded to n- and p-semiconductors is fabricated.
• Photoresponse from bulk excitons and direct carrier injection is demonstrated.
• System exhibits long distance exciton transport.

A solar cell of configuration N-[DDD----D]-P with a molecularly organized dye J-aggregate [DDD---D] electronically coupled to n- and p-type semiconductors is illustrated by fabricating a model device with TiO2 and CuSCN as the n- and p-type substrates and the thiocyanate of a cationic pentamethine cyanine dye as D. Functional moieties in D anchors to TiO2 establishing electronic coupling and serving as a template for assembly of a J-aggregated film. Bonding of sulfur in thiocyanate anions at the other end of the aggregate create the electronic coupling needed to facilitates transfer of holes to CuSCN. The cell exhibits photo-response originating from excitons generated in the bulk of the thick dye film as well as direct sensitized injection at the first interface. The dye molecular assembly is found to admit exciton transport over relatively long distances and significant hole mobility.