Nanofabrication of Organic/Inorganic Hybrids of TiO₂ with Substituted Phthalocyanine or Polythiophene

Organic photovoltaic cells, similar to Grätzel type, have been widely investigated in recent years. In the case of Grätzel-type cells, TiO₂ colloids are usually spin-coated onto an electrode and then sintered. Later, such electrodes are immersed in dye solution to sensitize the TiO₂ layer for fabrication of photovoltaic cells. In the current study, an attempt was made to fabricate photovoltaic cells using a layer-by-layer technique. Based on such a method, ordered substituted phthalocyanine or conducting polythiophene-sensitized TiO₂ multilayers were fabricated at the molecular level. Buildup of multilayer films of copper phthalocyanine-capped TiO₂ and poly(thiophene-3-acetic acid)/TiO₂ was monitored by increments in the UV-visible absorption and the frequency decrease of quartz crystal microbalance. The ordered multilayers were further characterized by infrared spectroscopy, and electrochemical and photoelectrochemical measurements.