Photophysics of segmented block PPV copolymer derivatives

The photophysics of the luminescent dimethoxy-substituted chromophore, [(2,6-dimethoxy-1,4 phenylene)-1,2 ethenylene-(2,5-dimethoxy-1,4 phenylene)-1,2 ethenylene-(3,5-dimethoxy-1,4 phenylene)] is studied in a series of segmented block copolymer, monomer, and polymer samples. Fluorescence lifetimes of the monomer and segmented block copolymer solution and thin film were determined over a temperature range from 77 to 298 K. Comparison of absorbance and emission spectra and time-resolved fluorescence studies indicate exciton confinement in the chromophore moities of the segmented block copolymer, leading to near unity quantum efficiency. Steady state absorption spectra show an increasing blue-shifted peak upon formation of the spin-coated thin film. Conformational geometry in the monomer thin film facilitates excimer formation, especially evident at low temperatures.