Exciton recombination dynamics in nanoring cycloparaphenylenes

We have studied the photoluminescence (PL) properties of [n]cycloparaphenylenes ([n] CPPs), which have simple string structures consisting of varying numbers of benzene rings, using steady-state and timeresolved PL spectroscopy. The PL lifetime decreased dramatically as the number of benzene rings increased, and increased with an increase in temperature. These results reveal that the exciton spreads beyond the benzene rings and that the temperature dependence of the PL lifetime is determined by thermal distribution of the excitons.