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

• Published in: ACS central science 2020-11, Vol.6 (11), p.2088-2096
• Main Authors: Ribson, Ryan D, Choi, Gyeongshin, Hadt, Ryan G, Agapie, Theodor
• Format: Article
• Language: English
• Subjects: Absorption; Aromatic compounds; Fluorescence; Hydrocarbons; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Nuclear fission
• ISSN: 2374-7943; 2374-7951
• DOI: 10.1021/acscentsci.0c01044

Singlet fission has the potential to surpass current efficiency limits in next-generation photovoltaics and to find use in quantum information science. Despite the demonstration of singlet fission in various materials, there is still a great need for fundamental design principles that allow for tuning of photophysical parameters, including the rate of fission and triplet lifetimes. Here, we describe the synthesis and photophysical characterization of a novel bipentacene dipyridyl pyrrole (HDPP-Pent) and its Li- and K-coordinated derivatives. HDPP-Pent undergoes singlet fission at roughly 50% efficiency (τSF = 730 ps), whereas coordination in the Li complex induces significant structural changes to generate a dimer, resulting in a 7-fold rate increase (τSF = 100 ps) and more efficient singlet fission with virtually no sacrifice in triplet lifetime. We thus illustrate novel design principles to produce favorable singlet fission properties, wherein through-space control can be achieved via coordination chemistry-induced multipentacene assembly.