The Pattern Replication In Non-wetting Templates (PRINT) technique has been extended to patterning of isolated
features as well as embossed films of sub-500 nm "hard" inorganic oxides and nanocrystalline semiconductors and "soft"
semiconducting polymers including TiO<sub>2</sub>, SnO<sub>2</sub>, ZnO, ITO, BaTiO<sub>3</sub>, CdSe, poly(3-hexylthiophene) (P3HT), Poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV), and other polythiophene derivatives. The
low surface energy, chemically resistant, air permeable elastomeric perflouropolyether (PFPE) based molds allow for
numerous materials to be patterned on a variety of substrates including glass, transparent conductive oxides, and thin
films of conducting polymer for a wide range of electronic and optical applications. Additionally, PRINT has been
employed to pattern features with aspect ratios greater than 1, deposit a second layer of features on top of an initial layer
without pattern destruction, and replicate sub-100 nm sized features for photovoltaics applications. Materials and
patterns generated in this work were characterized using a variety of techniques including: Scanning Electron
Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD).
We have fabricated bulk heterojunction photovoltaic (PV) cells using a perfluoropolyether (PFPE) elastomeric stamp to
control the morphology of the donor-acceptor interface within devices. Devices were fabricated using the Pattern
Replication In Non-wetting Templates (PRINT) process to have nanoscale control over the bulk heterojunction device
architecture. The low-surface energy, chemically resistant, variable modulus, fluoropolymer based molds used in
PRINT provide a route to patterning, with nanometer resolution, general polymeric donor materials such as
polythiophene and polyphenylenevinylene derivatives and 'hard' inorganic oxide structures typically used as acceptor
materials in hybrid organic solar cells such as TiO<sub>2</sub>, ZnO, and CdSe. This "top-down" approach allows for patterning
over large areas and for the functionalization of the donor/acceptor interface. Specifically, nanostructured anatase titania
with post-like features ranging from 30-100 nm in diameter and 30-65 nm in height was fabricated to form the ordered
bulk heterojunction of a titania-poly(3-hexylthiophene) (P3HT) PV-cell. Nanostructured devices showed a two-fold
improvement in both short-circuit current (J<sub>sc</sub>) and power conversion efficiency (PCE) relative to reference bilayer cells.
Additionally, we will discuss devices fabricated with other organic and inorganic materials in order to investigate the
effect on cell performance of controlling the nanoscale architecture of the bulk heterojunction via patterning.