Photophysical properties of PPP and PPV derivatives bearing polystyrene or polycaprolactone as side groups

This contribution reports on detailed photophysical investigations of poly(p-phenylene) PPP and poly(p-phenylene-vinylene) (PPV) derivatives laterally decorated with polystyrene (PPV-PSt) or poly(ε-caprolactone) (PPP-PCL, PPP-altPCL, PPV-PCL and PPV-PCL-Br). The polymers emit blue and exhibit very high relative and absolute photoluminescence quantum yield, Φf, in dilute solution, thin film (spin-coated and inkjet-printed) and bulk state. This is ascribed to the presence of the lateral macromolecules, which suppress the strong π–π interactions and consequently excimers formation. Lower Φf value was obtained for the bromine containing polymer and its corresponding model compound dibromodistyrylbenzene Br2-DSB, which was ascribed to heavy atom effect enabling intersystem crossing from S1 to T1. However, studies at 77 K did not reveal phosphorescence, in contrast an enhancement of the fluorescence intensity with respect to room temperature measurement was observed.