One approach for making inexpensive inorganic-organic hybrid photovoltaic (PV) cells is to fill highly ordered titanium dioxide (TiO2) nanotube arrays with solid organic hole conductors such as conjugated polymers. Center for Nanoscale Materials researchers and collaborative users from the University of Chicago present a new in situ ultraviolet (UV) polymerization method for growing polythiophene inside TiO2 nanotubes and compare this method to the conventional approach of infiltrating nanotubes with presynthesized polymer.
A nanotubular TiO2 substrate is immersed in a 2,5-diiodothiophene (DIT) monomer precursor solution and then irradiated with UV light. Complete photoluminescence quenching upon UV irradiation suggests coupling between radicals created from DIT and at the TiO2 surface via a charge transfer complex. A non-ideal backside-illuminated setup under illumination of 620-nm light yields a photocurrent density that is much stronger than comparable devices fabricated with polymer synthesized ex situ.
S. Tepavcevic, S.B. Darling, N.M. Dimitrijevic, T.Rajh, and S.J. Sibener, "Improved Hybrid Solar Cells via in situ UV-Polymerization," (accepted for publication in Small)