We investigated the ability of silver thin metal films to enhance photovoltaic conversion efficiency in blends of
poly-3-hexylthiophene (P3HT) and methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM). By varying
the thickness of the silver films and developing a new fabrication routine that involves annealing for long periods of time
at low temperatures, we were able to reproducibly enhance photoconversion in P3HT/PCBM devices. Photovoltaic
conversion efficiency was monitored using internal photon to current conversion efficiency (IPCE) and current-voltage
measurements. We observed that plasmonic materials were able to enhance the conversion efficiencies of organic, bulk
heterojunction devices. The relationship between the surface plasmon resonance wavelength and overall device
performance is also presented with IPCE data. These preliminary studies indicate that plasmonic enhancement in bulk
heterojunction devices show promise to improve the viability of organic solar cells.
This proceeding is a summary of our progress in both fundamental studies of surface enhanced Raman scattering (SERS) active surfaces and the design and characterization of nanostructured SERS-active surfaces. Based on the prior demonstration of single molecule SERS (smSERS)-like behavior from vapor deposited thin silver films, we've focused on these substrates as model systems for fundamental studies of the "blinking" phenomenon. Preliminary studies suggest that Stokes-shifted emission "blinking" is more directly associated with metal nanofeatures and less dependent on the nature of the adsorbate. It is anticipated that the insight provided by these fundamental studies will eventually lead to the rational design of nanostructured surfaces capable of smSERS. Toward that goal, preliminary characterization of the optical properties of nanoaperture arrays in silver suggests that these surfaces may exhibit SERS enhancement greater than that of the overlaying thin silver film.
This manuscript is a summary of our progress toward the development of nanoaperture arrays as surface enhanced Raman scattering (SERS) active surfaces. Nanopatterned substrates have been fabricated using electron beam lithography. The substrates were metallized by thermal vapor deposition of silver. The resulting silver films exhibited interesting optical transmission and preliminary results with respect to SERS are encouraging.