Nanostructured Titania−Polymer Photovoltaic Devices Made Using PFPE-Based Nanomolding Techniques

We fabricated ordered bulk heterojunction photovoltaic (PV) cells using a perfluoropolyether (PFPE) elastomeric mold to control the donor−acceptor interfacial morphology within devices. Anatase titania nanostructures with postlike features ranging from 30 to 100 nm in height and 30 to 65 nm in spacing were fabricated using the Pattern Replication In Nonwetting Templates (PRINT) process. The nanostructured devices showed a 2-fold improvement in both short-circuit current ( J sc ) and power conversion efficiency (PCE) relative to reference bilayer cells. Additionally, the titania was functionalized with Z907 dye to increase both the short-circuit current ( J sc ) and open-circuit voltage ( V oc ). As a result we observed a device efficiency (η eff ) of 0.6%, the highest recorded efficiency value so far for an imprinted titania−P3HT device.