Spatially and temporally resolved emission from aggregates in conjugated polymers

We present results of cw, time-resolved, and spatially resolved spectroscopic studies of emission and absorption in a model conjugated polymer, poly($p$-pyridyl vinylene) (PPyV). The redshifted film spectra suggest the formation of aggregated regions. The ∼4× reduction in emission efficiency in films vs solution is attributed to a longer radiative lifetime for aggregate excitons, as is evidenced by time-resolved fluorescence measurements. We present direct optical imaging of aggregates in a conjugated polymer via near-field scanning optical microscopy. The aggregate emission and absorption are found to be localized to partially aligned regions of the film ∼200 nm in size.