Singlet Fission and 1,3-Diphenylisobenzofuran as a Model Chromophore

A brief description is provided of a phenomemon known as singlet fission (SF), in which a singlet excited chromophore and a ground state chromophore share energy to produce two triplet excited chromophores. In principle, the process permits the absorption of a single photon to produce two electrons and two holes, leading to a theoretical solar cell efficiency close to 1/2, significantly above the 1/3 Shockley–Queisser limit. The prerequisites for efficient singlet fission are considered, both in terms of the properties of individual chromophores and in terms of their mutual coupling. The design rules for efficient chromophores derived from first principles led to the formulation of a model system, 1,3-diphenylisobenzofuran. This chromophore is used to illustrate the singlet fission process and the complications that can arise.