Optimising P3HT/PCBM Organic Photovoltaic Cells: Identifying Key Parameters

  • Prof Jeffrey Reimers, School of Chemistry, The University of Sydney, Australia
  • Prof Maxwell Crossley, School of Molecular and Microbial Biosciences, The University of Sydney, Australia
  • Prof Noel Hush, The University of Wollongong, Australia
  • Dr David Officer, ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Australia
  • Dr Paul Dastoor, School of Mathematical and Physical Sciences, University of Newcastle, Australia

    • Porphyrins are added in ternary blends of organic fullerene-polymer solar cells, allowing the concentration of polymer in functioning polymer/fullerene blends to be reduced to under 10% with little impact on device functionality. By varying the concentrations in this low-doping region, the solar cell absorption is partitioned into contributions from each component. This allows the observed internal quantum efficiency (IQE) to be partitioned into contributions based on the nature of the absorbing material (polymer, fullerene, or porphyrin). Addition of the porphyrin increases the IQE following light absorption by the polymer or fullerene, adds broadband character to the photocurrent, but slightly decreases the open-circuit voltage so that the overall efficiency changes only slightly. Most significantly, the IQE partitioning process reveals that the majority of the photocurrent produces in "standard" (20%) polymer/fullerene solar cells is produced following light absorption by the fullerene. This result connects with known results for fullerene-oligomer dyads that demonstrate significant primary charge separation following fullerene irradiation.