“…The emission spectrum of the MCs is red-shifted relative to the emission spectrum of the perylene molecule, as expected due to the aggregation of perylene in the MCs. The emission of solid-state perylene has been well studied, and it is generally understood to be made up of emission from E-type and Y-type excimers. ,,,,, The E-type excimer is formed on the perylene sandwich dimer, while the Y-type excimer is formed in the next-nearest parallel pair of molecules. In perylene single crystal studies, the E-type excimer is observed at room temperature, whereas the Y-type excimer is only observed at low temperatures (10–30 K). , In perylene microcrystals, however, both the E- and Y- types are observed at room temperature. ,, In the observed emission spectra for the plate-, rod-, and cube-shaped perylene MCs, the peak around 575 nm is attributed to the formation of an E-type excimer, while the shoulder at 520 nm is attributed to the Y-type excimer. ,, The Y-states are populated from the optically excited monomeric singlet (S 1 state), whereas the E-states are generated by the thermally activated energy transfer from the Y-state .…”