A design strategy for intramolecular singlet fission mediated by charge-transfer states in donor–acceptor organic materials

• Published in: Nature materials 2015-04, Vol.14 (4), p.426-433
• Main Authors: Busby, Erik, Xia, Jianlong, Wu, Qin, Low, Jonathan Z., Song, Rui, Miller, John R., Zhu, X-Y., Campos, Luis M., Sfeir, Matthew Y.
• Format: Article
• Language: English
• Subjects: 119/118; 140/125; 140/131; 639/301/299; 639/638/455/958; Biomaterials; Condensed Matter Physics; Coupling (molecular); Design; Electronic structure; Excitation; Fission; Guidelines; Materials Science; Nanotechnology; Optical and Electronic Materials; Optical properties; Organic materials; Polymers; Semiconductor research; solar (photovoltaic), electrodes - solar, charge transport, materials and chemistry by design, optics, synthesis (novel materials); Strategy
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/nmat4175

The ability to advance our understanding of multiple exciton generation (MEG) in organic materials has been restricted by the limited number of materials capable of singlet fission. A particular challenge is the development of materials that undergo efficient intramolecular fission, such that local order and strong nearest-neighbour coupling is no longer a design constraint. Here we address these challenges by demonstrating that strong intrachain donor–acceptor interactions are a key design feature for organic materials capable of intramolecular singlet fission. By conjugating strong-acceptor and strong-donor building blocks, small molecules and polymers with charge-transfer states that mediate population transfer between singlet excitons and triplet excitons are synthesized. Using transient optical techniques, we show that triplet populations can be generated with yields up to 170%. These guidelines are widely applicable to similar families of polymers and small molecules, and can lead to the development of new fission-capable materials with tunable electronic structure, as well as a deeper fundamental understanding of MEG. Design rules for the synthesis of donor–acceptor systems with efficient intramolecular singlet fission are now proposed. These guidelines have been applied to both small molecules and polymeric chains.