Sensitizer design for efficient triplet–triplet annihilation upconversion: annihilator-appended tris-cyclometalated Ir(iii) complexes

Abstract

Enhanced triplet–triplet annihilation upconversion efficiency is achieved with two tris-cyclometalated iridium sensitizers covalently tethered with a pyrene annihilator. The improved sensitizing ability and very long phosphorescence lifetimes (1–2 ms) of these bichromophore molecules are both attributed to the intramolecular energy transfer between the iridium complex and appended pyrene group.