Characterization of New Materials for Photovoltaic Thin Films: Aggregation Phenomena in Self-Assembled Perylene-Based Diimides
Abstract
Under this grant, a new class of organic photovoltaic materials have been developed and characterized. These materials are comprised of cationic symmetrically- and asymmetrically-substituted perylene diimides and oppositely charged poly(acrylate) polyanions. Thin films of these materials yield photovoltages of >140 mV for approximately 0.6 W/sq cm illumination intensities, when incorporated into rudimentary heterojunction devices. Solution phase fluorescence spectra obtained from the complexes exhibit excimer-like emission and evidence of weakly coupled ground-state aggregates. Small-angle X-ray diffraction indicates the films incorporate planar bilayers of the diimide and polyanion having 3.9 nm repeat distances. Scanning probe microscopy images show the films are heterogeneous, and are comprised of sub-micrometer sized clusters that incorporate the diimide. Polarization-dependent optical imaging studies prove the perylene chromophores are semi-organized in these clusters. Application of an electric field across the films induces a depth-dependent change in the fluorescence. This effect is attributed to reorientation of the perylene chromophores under the influence of the applied field.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 21, 2005
- Accession Number
- ADA435695
Entities
People
- Aifang Xie
- Bei Liu
- Daniel A. Higgins
Organizations
- Kansas State University