Lessons from intramolecular singlet fission with covalently bound chromophores

Abstract

Molecular dimers, oligomers, and polymers are versatile components in photophysical and optoelectronic architectures that could impact a variety of applications. We present a perspective on such systems in the field of singlet fission, which effectively multiplies excitons and produces a unique excited state species, the triplet pair. The choice of chromophore and the nature of the attachment between units, both geometrical and chemical, play a defining role in the dynamical scheme that evolves upon photoexcitation. Specific final outcomes (e.g., separated and uncorrelated triplet pairs) are being sought through rational design of covalently bound chromophore architectures built with guidance from recent fundamental studies that correlate structure with excited state population flow kinetics.

Designs of Singlet Fission Chromophores with a Diazadiborinine Framework**

“…[13,14] In oligomers, nanoclusters, and solids of chromophores, delocalization of S 1 over several molecules occurs. [15][16][17][18] Since the SF process involves charge-transfer states between adjacent chromophores [1][2][3]19] and the generated triplet excitons are also confined within adjacent chromophores, [20,21] the dimer description, although incomplete, still captures the essence of SF. [22] One main difficulty that hinders of the exploitation of SF in photovoltaics is the small pool of molecules that can exhibit this phenomenon.…”

Controlling Singlet Fission with Coordination Chemistry-Induced Assembly of Dipyridyl Pyrrole Bipentacenes

“…It is likely that these structural perturbations lead to a pronounced rate Table S13). 22 The structural control over the two chromophores demonstrated here is thus significant with respect to achieving efficient singlet fission without concomitant acceleration of triplet pair decay pathways.…”

Porous Shape-Persistent Rylene Imine Cages with Tunable Optoelectronic Properties and Delayed Fluorescence

“…The rate of S † formation also increases with solvent polarity in accord with the CT-mediated mechanism of singlet fission. 34,39,40 Therefore, we propose that the S † is most likely the correlated triplet pair 1 ( 3 PDI••• 3 PDI). A fully recovered background signal within a few hundred nanoseconds in the TCSPC experiments suggests that the free PDI triplets do not form or they recombine slower than their triplet lifetime.…”