Pentacenes: A Molecular Ruler for Singlet Fission

Surpassing the Shockley–Queisser limit, which places an upper bound on solar conversion efficiency for a single p–n junction solar cell at slightly more than 30%, is one of the grand challenges in the field of solar-energy research. Singlet fission (SF) in molecular acenes, the molecular analog of multiple exciton generation (MEG), has the potential to initiate a game-changing advance in solar-energy conversion. SF allows singlet-excited states (S 1 ) to be down-converted into twice as many triplet-excited states (T 1 ).