Hybrid polymer-based photovoltaics via carbon nanotubes and electrostatic self-assembly

Recently, there has been increased interest in polymer-based photovoltaic devices due to their promise for the creation of lightweight, flexible, and inexpensive electrical power. We examined the possibility of using nanoparticles and nanoparticles with tailored interfaces for the creation of hybrid polymer-based devices with enhanced photovoltaic response. Initially, we investigated the incorporation of multi-walled carbon nanotubes (MWNT) in the poly(benzimidazo-benzophenanthroline) ladder (BBL) layer of two-layer poly(p-phenylene vinylene) (PPV)-BBL photovoltaic devices. Subsequently, we explored the possibility of tuning polymer-particle interfaces through the creation of core-shell particles fabricated using electrostatic self-assembly. For the PPV/BBL(MWNT) devices, a doubling of the photocurrent and a drastic reduction in photovoltage with MWNT incorporation is observed for a range of BBL layer thickness values. This behavior is consistent with the MWNTs functioning as a three dimensional extension of the top aluminum electrode. Fabrication studies on core-shell particles demonstrate that the interfacial properties of a variety of particles can be manipulated, shells of up to 10 bilayers can been achieved, and TiO₂ nanoparticles with PPV polymer shells are possible.