Tuneable Singlet Exciton Fission and Triplet-Triplet Annihilation in an Orthogonal Pentacene Dimer

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Lukman, S 
Musser, AJ 
Chen, K 
Athanasopoulos, S 
Yong, CK 

We report fast and highly efficient intramolecular singlet exciton fission in a pentacene dimer, consisting of two covalently attached, nearly orthogonal pentacene units. Fission to triplet excitons from this ground state geometry occurs within 1 ps in isolated molecules in solution and dispersed solid matrices. The process exhibits a sensitivity to environmental polarity and competes with geometric relaxation in the singlet state, while subsequent triplet decay is strongly dependent on conformational freedom. The near orthogonal arrangement of the pentacene units is unlike any structure currently proposed for efficient singlet exciton fission and may lead to new molecular design rules.

dimers, pentacenes, singlet fission, triplet-triplet annihilation, vibrational relaxation
Journal Title
Advanced Functional Materials
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Engineering and Physical Sciences Research Council (EP/M005143/1)
Engineering and Physical Sciences Research Council (EP/G060738/1)
JW acknowledges financial support from Singapore MOE Tier 3 grant (MOE2014-T3-1-004). SL thanks AGS Scholarship support from the A*STAR Singapore. The work was supported by the EPSRC (grant number EP/G060738/1). We acknowledge the use of the Darwin Supercomputer of the University of Cambridge High 18 Performance Computing Service (http://www.hpc.cam.ac.uk/) and the EPSRC UK National Service for Computational Chemistry Software (NSCCS) at Imperial College London in carrying out this work.