Spectral properties and photophysics of arylacetylenes in thin-films

We report the photobehaviour of a series of eight structurally related arylacetylene derivatives, in solution as well as in pristine and PC61BM blended thin- lms. The formation of both H- and J-aggregates in the solid state have been demonstrated, and, interestingly, an energy transfer from H-aggregates or/and from residual "unstacked" molecules to J-aggregates has been found, the latter being the only emitting species. The uorescence quenching by PC61BM at di erent loadings has been studied in blend lms, and it has been found particularly e - cient in the case of a symmetrical peripheral substitution of the acetylene derivative core. Preliminary time-resolved measurements in emission (ns resolution) and in absorption (fs resolution) con rmed the H!J energy transfer and underlined the presence of delayed uorescence from Jaggregates, formed by energy transfer from the long-lived rst excited singlet state of H-aggregates. In all cases, a homogeneous surface morphology of thin- lms was identi- ed by confocal uorescence microscopy.