Ultrabright AIE of Ir(III) complexes achieving expeditious monitoring of oxygen and high-definition development of latent fingerprints

Abstract AIEgens have been widely applied in the fields involving solid and aggregation states. However, the preparation of AIEgens with high brightness to obtain the optimum AIE performance remains a challenge. In this article, a finely structural design strategy for the creation of ultrabright AIEgens has been reported based on Ir(III) complexes. By stepwise heightening the motion activity of substituents, the AIE property of Ir(III) complexes can be activated with dramatically improved photoluminescence quantum yields in solid state. The dipole moment vector of substituents and the triplet lifetime of Ir(III) complexes were applied to verify the motion activity of substituents theoretically and experimentally. In addition, by the combination of AIE-active Ir(III) complex IrppyDPBA and air permeable, optically transparent ethylcellulose, a hypersensitive luminescent oxygen sensing film with ultrafast quenching/recovery cycles in 6.1 s was developed. And the high-brightness AIE significantly improved the oxygen sensitivity of Ir(III) complexes. Furthermore, the expeditious and high-definition development of latent fingerprints on the substrates of tinfoil, plastic, steel, and glass was demonstrated by the high-brightness AIE of IrppyDPBA in 3 min. The fingerprint photographs developed by IrppyDPBA were intact and legible enough to allow display and analyze down to level 3 details. Noteworthily, the synergistic enhancement of the AIE property and the RTP nature of Ir(III) complexes on LFP development was for the first time demonstrated.