Electronic communication in tetrathiafulvalene (TTF)/C60 systems:: Toward molecular solar energy conversion materials?

The covalent connection of the electron acceptor C-60 to P- quinonoid pi-extended tetrathiafulvalenes (exTTFs) has allowed for the preparation of new photo- and electroactive conjugates able to act as artificial photosynthetic systems and active molecular materials in organic photovoltaics. The gain of aromaticity undergone by the T-extended TTF unit in the oxidation process results in highly stabilized radical ion pairs, namely, C-60(center dot-)/exTTF(center dot+). Lifetimes for such charge- separated states, ranging from a few nanoseconds to hundreds of microseconds, have been achieved by rationally modifying the nature of the chemical spacers. These longlived radical pairs are called to play an important role for the conversion of sunlight into chemical or electrical power.