Efficient Singlet Fission and Triplet-Pair Emission in a Family of Zethrene Diradicaloids

• DOI: 10.1021/jacs.7b10762
• Publication Date: 2017-11-22T15:13:16Z
• Authors: Steven Lukman; Johannes M. Richter; Le Yang; Pan Hu; Jishan Wu; Neil C. Greenham; Andrew J. Musser
• Keywords: Diradical; Singlet fission; Chromophore

Singlet fission offers the potential to overcome thermodynamic limits in solar cells by converting energy of a single absorbed photon into two distinct triplet excitons. However, progress is limited small family suitable materials, and new chromophore design principles are needed. Here, we experimentally vindicate concept diradical stabilization tunable functionalized zethrenes. All molecules series exhibit rapid formation bound, spin-entangled triplet-pair state TT. It can be dissociated thermally activated hopping exhibits surprisingly strong emission for an optically "dark" state, further enhanced with increasing character. We find that TT excited-state absorption spectral shape correlates binding between constituent triplets, providing tool understand this unusual state. Our results reveal versatile materials excellent optical photochemical properties exploitation singlet devices.