Intermolecular sequential energy transfer in thin films of a white emitting copolymer.

The authors investigated the energy transfer between the chromophors of a white emitting polyspirobifluorene copolymer containing a blue emitting backbone, a green, and a red emitting dye. They demonstrate that the green dye is mainly excited by blue→green Förster resonant energy transfer (FRET), with a Förster radius R_0bg=35 Å. The red dye is instead excited by direct blue→red FRET (R_0br=21 Å) and by sequential blue→green→red FRET (R_0gr=31 Å). Finally, the authors show that the FRET processes, fundamental to have white emission, are of intermolecular nature, while intramolecular energy migration and transfer are negligible. [ABSTRACT FROM AUTHOR]