Annealing temperature dependence of the size of C-60 clusters in C-60-doped silicon oxide films

C-60-doped silicon oxide thin films were prepared by spin-coating a viscous solution formed upon soaking at 40 degreesC an acidic toluene/ethanol solu tion of C-60, phenyltriethoxysilane, and tetraethoxysilane with a C-60-to-S i molar ratio of 2.5 x 10(-3). The films were submitted to annealing at 300 -500 degreesC in Ar to investigate variation in the size of C-60 clusters e mbedded in the films by photoluminescence spectroscopy. The film before ann ealing was found to contain the clusters consisting of ca. 60 C-60 molecule s, suggesting that C-60 is present well-dispersed in the film. The molecule s in the film aggregated to increase the size with increasing annealing tem perature, indicating that the molecules diffuse easily in the film upon hea ting and therefore the size of the clusters is controllable with the anneal ing temperature.