The two-step excimer formation in perylene crystals

Low-lying excited states in crystalline perylene

“…The optical spectra of molecular crystals based on polyaromatic conjugated hydrocarbons feature strongly bound excitons, with binding energies of several hundreds of millielectronvolts, as well as significant singlet-triplet exchange splittings on the same energy scale. Both are comparable to intermolecular binding energies occurring in these van der Waals-bound solids (3)(4)(5)(6). Furthermore, the large singlettriplet splittings can facilitate singlet exciton fission, a carrier multiplication mechanism which enables quantum efficiencies beyond the Shockley-Queisser limit (7).…”

Self-aggregates formation of 3,4,9,10-tetra-(n-alkoxy-carbonyl)-perylenes in Langmuir–Blodgett films

“…Meanwhile, the fluorescence spectrum loses the structured form already at MFE0.015 and the shift of the maximum position at this concentration compared to that of monomer is E30 nm (at MF ¼ 0.8 the shift is 460 nm). The shape and the maximum position of the fluorescence band, which has no equivalent band in the absorption spectrum, could be indicative that we deal here with Y-type emission [15,16,[32][33][34] originates from the precursor for the fully relaxed excimer.…”

“…Willig et al [20,22] made the detailed analysis of the temperature effect on the fluorescence and its lifetime for the LB film of one of perylene derivatives mixed with arachid acid. They ascribed the bands appearing in the fluorescence spectrum with maxima at about 550 and 630 nm (at 2 K) to, respectively, Y-type and E-type emissions, which are characteristic also for a-perylene crystal [32][33][34]. Y-type emission originates from a partially relaxed excited molecular pair, while E-type emission is related to the fully relaxed excimer.…”

Electronic absorption and fluorescence of new tetrafluoro-pentenyl-perylene in isotropic solvents, liquid crystal layers, and LB films

“…The analysis of the electronic absorption and fluorescence spectra of LB films deposited on quartz plates has been conducted. In the fluorescence spectra the bands characteristic of Y-type emission from the lower excited g-state of the stable parallel dimer and E-type luminescence, attributed to the configuration with the strongest interaction in the excited dimer analogous to that of a-perylene crystal [12,25,26], have been found. The results have enabled one to draw a conclusion that the perylenes mixed with liquid crystal (8CB) create aggregates in the ground state.…”