Nanostructured electrodes and interfaces can enhance light absorption in organic solar cells due to efficient light harvesting. Ultrathin films of an active layer (C60) deposited on nanostructured grating electrodes show more absorption as a result of increased light trapping. Plasmonic nanostructured electrodes with various geometries and dimensions have been fabricated on printed polyacrylonitrile (PAN) and subsequently characterized. Surface enhanced Raman scattering (SERS) measurements show significant signal enhancement (over two orders of magnitude) on nanostructured samples when compared to planar Ag substrates due to local electromagnetic field enhancement. Furthermore, conversion of PAN to graphitic carbon is evidenced in SERS spectra. The surface area was determined using underpotential deposition (UPD) of thallium and agrees with the geometric surface area calculated from SEM images. The FDTD simulated electric field distribution inside the samples confirms the experimental results. A 60 fold increase in the electric field results in three to four orders of magnitude enhancement in the SERS signal depending on the dimensions of the pillars and gratings. Further study of the interaction between a top organic layer (C60) and the Ag electrode will help us to understand the nanoscale charge transfer rate critical to optimization and design of efficient organic solar cells.

Date Published: 18 September 2013
PDF: 7 pages
Proc. SPIE 8809, Plasmonics: Metallic Nanostructures and Their Optical Properties XI, 88091L (18 September 2013); doi: 10.1117/12.2024333

Published in SPIE Proceedings Vol. 8809:
Plasmonics: Metallic Nanostructures and Their Optical Properties XI
Mark I. Stockman, Editor(s)