AVS 62nd International Symposium & Exhibition
    Electronic Materials and Processing Thursday Sessions
       Session EM+EN-ThA

Paper EM+EN-ThA10
Symmetry-Breaking in Periodic Nanostructures for Enhanced Light Trapping in Organic Solar Cells

Thursday, October 22, 2015, 5:20 pm, Room 211C

Session: Materials for Light Management
Presenter: Seok Jun Han, University of New Mexico
Authors: S.J. Han, University of New Mexico
S. Ghosh, University of New Mexico
O.K. Abudayyeh, University of New Mexico
E.J. Martin, University of New Mexico
J.K. Grey, University of New Mexico
S.M. Han, University of New Mexico
S.E. Han, University of New Mexico
Correspondent: Click to Email
In this study, we introduce a new light-trapping scheme for organic solar cells by systematically breaking the symmetry in periodic nanostructures on the bottom metal contact. To create symmetry-breaking metal nanostructures, we start by fabricating a mold from a crystalline silicon (c-Si) substrate. We intentionally misalign the etch mask with respect to [110] crystallographic orientation of the c-Si. Subsequently, silver is sputter-coated over the nanoscale recess created in the c-Si substrate to create the metal nanostructures, and an organic photoactive material, PCPDTBT, is spin-coated on the silver layer. The enhancement in light absorption is achieved at surface plasmon resonances at the polymer-metal interface. We demonstrate that surface plasmon band structure can be tailored by symmetry-breaking. In experiment, we increase the number of surface plasmon bands in the visible spectrum and locate the bands at the desired wavelengths by controlling the symmetry. In general, by patterning a flat film in symmetry-breaking structures, absorption is enhanced from 65% to 85% in a broad short wavelength spectrum. Moreover, the absorption spectrum is extended into long wavelengths by 20 nm. We expect that our low-cost, symmetry-breaking fabrication strategy would be scalable and lead to a manufacturable process for efficient light-trapping in organic photovoltaic devices.