A structure-property-performance investigation of perylenediimides as electron accepting materials in organic solar cells.

Solution-processed perylenediimides (PDIs) with varying peri and bay substituents are characterized in order to better understand the relationships between molecular structure, solid state order, charge transport, and photovoltaic performance. It was found that bulky bay substituents interfere with molecular packing, leading to low charge transport and photovoltaic efficiencies compared to PDIs with fewer or less disruptive substituents. We assessed the potential of PDIs as acceptors for organic photovoltaics (OPVs) by utilizing a solution-processed bilayer OPV device architecture with the donor benzoporphyrin. At AM1.5G illumination, power conversion efficiencies (PCEs) up to 2.0% are obtained for solution-processed bilayer OPVs employing PDIs as acceptors. These results demonstrate the potential of PDIs as photovoltaic acceptor materials while elucidating the relationships between molecular structure and material properties.

The theoretical current-voltage dependence of a non-degenerate disordered organic material obtained with conductive atomic force microscopy.

We develop a simple continuum model for the current voltage characteristics of a material as measured by the conducting atomic force microscopy, including space charge effects. We address the effect of the point contact on the magnitude of the current and on the transition voltages between the different current regimes by comparing these with the corresponding expressions obtained with planar electrodes.