Interaction of a Poly(phenylene vinylene) with an Organometallic Lewis Acid Additive. Fundamentals and Application in Polymer Solar Cells

The trimeric perfluoro-o-phenylene mercury compound Hg3 and poly(2-methoxy,5-(2’-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV) interact strongly in solution and the solid state. The interaction is attributed to electron donor-acceptor complex formation, where MEH-PPV is the donor, and the Lewis acid Hg3 is the acceptor. The study reported herein explores the effects of the donor-acceptor complex formation on the properties of MEH-PPV in solution and in the solid-state. Addition of Hg3 to MEH-PPV solution or films leads to a distinct color change, and the change in the visible absorption spectrum and fluorescence of MEH-PPV is consistent with the formation of polymer aggregates. In the solid state, Hg3 induced aggregation is suggested to lead to formation of crystalline domains of the conjugated polymer. Transmission electron microscopy and grazing incidence X-ray scattering results support the hypothesis that the complex formation with Hg3 induces aggregation of the polymer. Transient absorption spectros...