Synthesis and properties of [60]fullerene-polyvinylpyridine conjugates for photovoltaic devices

A two-phase radical polymerization was applied for the synthesis of fullerene-containing poly(4-vinylpyridine), which were used as polyelectrolytes in the fabrication of photovoltaic devices. Two-phase radical polymerization resulted in the products of poly(4-vinyl pyridinated) fullerenes (PVPyF) containing a high fullerene content and poly(4-vinylpyridine) arms of short length. These polyelectrolytes with a C₆₀ content of up to 35% by weight are soluble in organic solvents and water at a low Ph. High efficient photoinduced charge transfer in samples of PVPyF and polyanionic polythiophene derivatives fabricated by the electrostatic layer-by-layer deposition technique in producing self-assembled multilayers (SAMs) was demonstrated. As a result, high response to the increase of photoinduced conductivity was observed on the 75 bilayer device of PVPyF-3⁺/H-PURET^- upon irradiation. Photoconductivity was found to increase in more than one order of magnitude from 0.024 to 0.31 S/cm at an applied voltage of 1.0 volt. The sign of short-circuit photocurrent was consistent with electrons flowing from Al electrode towards the ITO modified substrate.