Acenes, Pentacene and Tetracene in particular, are prominent candidates for singlet fission. The energy of the triplet states are smaller than or equal to half of the singlet (S 1) state energy, thus satisfying the requirement of S 1 ≥ 2T 1. Singlet fission in functionalized pentacene compounds has been observed experimentally. Intramolecular singlet fission in covalently linked pentacene and tetracene dimers has also been reported.