Facile Microwave Synthesis of a Narrow-Band Green-Emitting Phosphor Cs 3 MnBr 5 and the Effect of Anion Substitution on Its Luminescence Properties.

A bright blue light excitable and narrow-band green-emitting phosphor Cs 3 MnBr 5 has been synthesized by a facile microwave radiation method within 2 min. The influence of the matrix on its steady-state and transient-state luminescence properties is investigated by partial substitution of Br - ions by Cl - ions. The incorporation of Cl - ions in Cs 3 Mn(Br 1- x Cl x ) 5 resulted in almost no change in the emission maxima of Mn 2+ , which is attributed to the synergistic effect of reduced covalency and increased crystal field strength caused by the replacement of Br - ions by Cl - ions. Meanwhile, the emission of Mn 2+ decreases with the increasing Cl - content, which is caused by different thermal quenching of Mn 2+ emission in the mixed Cl - /Br - coordination. Moreover, the incorporation of Cl - in Cs 3 Mn(Br 1- x Cl x ) 5 was found to have different effects on the lifetime of Mn 2+ at different temperatures, that is, at room temperature, the lifetime of Mn 2+ decreases with the increasing Cl - content, while at liquid nitrogen temperature, the lifetime of Mn 2+ increases upon increasing the Cl - content. The former is due to the different thermal quenching for different coordinations of Mn 2+ with Cl - and Br - , while the latter is due to the weaker spin-orbit coupling of the Mn 2+ ion caused by the interaction with the lighter Cl - ions, which makes the spin selection rule stricter and leads to a longer lifetime of Mn 2+ consequently.