A new solution-processable fabrication protocol using a soluble tetrabenzoporphyrin (BP) precursor and bis(dimethylphenylsilylmethyl)[60]fullerene (SIMEF) created three-layered p-i-n photovoltaic devices, in which the i-layer possesses a well-defined bulk heterojunction structure in which columnar BP crystals grow vertically from the bottom p-layer. The device showed a power conversion efficiency of 5.2% (V(OC) = 0.75 V; J(SC) = 10.5 mA/cm(2); FF = 0.65).

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The influence of shear flow of solvent past poly(methyl methacrylate) chains adsorbed onto germanium oxide from dilute carbon tetrachloride solution (a near-θ solvent) was studied at shear rates from 0 to 4 × 104 s-1 with the new apparatus described in this paper. Both the adsorbed amount and the flow-induced surface orientation (surface dichroism) were measured. The method involved measurements of infrared spectroscopy in attenuated total reflection (FTIR-ATR) using a hemispherical ATR crystal whose position with respect to the incident infrared source was rotated by 90° during the experiment in order to measure infrared absorbance in orthogonal directions. shear flow appeared to flatten the adsorbed PMMA layer relative to the surface. However, alignment of the polymer orientation in the direction of flow was found to be small. This suggests that shear-induced desorption (controlled by stress) and relaxation in response to deformation within the adsorbed layer (controlled by time) may be largely independent.

Thermal annealing of a p-i-n organic photovoltaic device containing a crystalline benzoporphyrin donor and solvated crystals of a silylmethylfullerene acceptor increases the device performance at a temperature where partial desolvation of the acceptor produces an amorphous mesophase. This suggests that the mesophase improves the hierarchical ordering of the materials, that is, the morphology of the n-layer and the interfacial contact and, hence, the carrier generation efficiency at the donor-acceptor interface.