Fluorene co-polymer luminescence: implications for molecular interactions

A co-polymer of fluorene and di-alkoxyphenylene has been studied by means of optical spectroscopy. The absorption spectra of solution and films have a maximum at 350 nm, In thick films additional bands at 450 nm and at 550 nm could also be observed. The luminescence of the solution phase has a maximum at 420 nm while the films exhibit two maxima with the stronger one located at 420 nm and the weaker one at 540 nm. The photoluminescence quantum yield of the solution was found to be 50% which was reduced to 7% for films. Our observations point to the formation of a strongly coupled aggregate, when going from the liquid to the solid phase.