Orientation and photoluminescence of C-60 crystallites in C-60-polymethyl methacrylate films

X-Ray diffraction measurements indicate that C-60 embedded in polymethyl me thacrylate have a high tendency to form crystallites, the size of which inc reases with C60 concentrations. Annealing results in the growth of C-60 cry stallites and for heavily doped films, rearrangement of them into a predomi nant (111) orientation. The samples produce intense double-peaked photolumi nescence profiles centered at similar to 1.7 and similar to 2.0 eV that var y coordinately upon annealing. The results not only promise an efficient me thod for preparation of oriented C-60 films on substrates exhibiting strong surface energies such as Si, but also demonstrate the importance of contro lling the size distribution of embedded C-60 crystallites for, e.g. obtaini ng desired photoluminescence. (C) 2000 Elsevier Science S.A. AU rights rese rved.