The first transition metal phthalocyanines: sensitizing rubrene emission based on triplet-triplet annihilation.

Metallophthalocyanines (MPc-o-Cou, M = Fe, Co, Ni, and Cu) with fourth period metal ions have been successfully applied as a sensitizer coupled with rubrene (Rub) in photon upconversion based on triplet-triplet annihilation. An upconversion quantum yield (ϕPUC) of up to 4.82% was observed in the CoPc-o-Cou : Rub couple. The absorption and phosphorescence emission spectra showed that the Q bands and phosphorescence emission peaks were dramatically dependent on the number of d-electrons of the metal ions in MPc-o-Cou. These results suggested that the photon upconversion behavior of MPc-o-Cou : Rub systems could be managed by altering the metal ions in MPc-o-Cou.