Inducing NIR long persistent phosphorescence in Cr-doped perovskite titanate via redox

• An interesting optical phenomenon of inducing the NIR long persistent phosphorescence.
• A novel NIR Cr-doped non-gallate persistent phosphors, CaTiO3: Cr3+ with emission band 650–850 nm.
• An effective way to develop the novel phosphorescent phosphors quickly and effectively.
• Breaking the monopoly of Cr3+-activated gallate phosphors.

We report a simple approach to activate the near-infrared (NIR) long persistent phosphorescence via redox reaction. NIR long persistent phosphorescence is observed in a Cr-doped non-gallate phosphor, i.e. CaTiO3: Cr with perovskite structure through heat treatment in reducing atmosphere, while no such phenomenon is observed in the sample with same composition and heat treated in air. The mechanism for activation of Cr-related long persistent phosphorescence is discussed. The designed phosphors successfully break the monopoly of the ordinary Cr3+-activated gallate phosphors with the spinel structure and provides a new route for design of long persistent phosphors.