Singlet Exciton Fission in Polycrystalline Thin Films of a Slip-Stacked Perylenediimide

The crystal structure
of N,N-bis­(n-octyl)-2,5,8,11-tetraphenylperylene-3,4:9,10-bis­(dicarboximide), 1, obtained by X-ray diffraction reveals that 1 has a nearly planar perylene core and π–π stacks
at a 3.5 Å interplanar distance in well-separated slip-stacked
columns. Theory predicts that slip-stacked, π–π-stacked
structures should enhance interchromophore electronic coupling and
thus favor singlet exciton fission. Photoexcitation of vapor-deposited
polycrystalline 188 nm thick films of 1 results in a
140 ± 20% yield of triplet excitons (3*1) in τSF = 180 ± 10 ps. These results illustrate
a design strategy for producing perylenediimide and related rylene
derivatives that have the optimized interchromophore electronic interactions
which promote high-yield singlet exciton fission for potentially enhancing
organic solar cell performance and charge separation in systems for
artificial photosynthesis.