Macroscopic Molecular Ordering and Exciton Delocalization in Crystalline Phthalocyanine Thin Films.

We present spatially-, temporally- and polarization-resolved dual photoluminescence/linear dichroism microscopy experiments that investigate the correlation between long-range order and the nature of exciton states in solution-processed phthalocyanine thin films. The influence of grain boundaries and disorder is absent in these films because typical grain sizes are 3 orders of magnitude larger than focused excitation beam diameters. These experiments reveal the existence of a delocalized singlet exciton, polarized along the high mobility axis in this quasi-1D electronic system.