Facile Microwave Synthesis of a Narrow-Band Green-Emitting Phosphor Cs3MnBr5 and the Effect of Anion Substitution on Its Luminescence Properties

A bright blue light excitable and narrow-band green-emitting phosphor Cs3MnBr5 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 Cs3Mn(Br1-xClx)5 resulted in almost no change in the emission maxima of Mn2+, 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 Mn2+ decreases with the increasing Cl- content, which is caused by different thermal quenching of Mn2+ emission in the mixed Cl-/Br- coordination. Moreover, the incorporation of Cl- in Cs3Mn(Br1-xClx)5 was found to have different effects on the lifetime of Mn2+ at different temperatures, that is, at room temperature, the lifetime of Mn2+ decreases with the increasing Cl- content, while at liquid nitrogen temperature, the lifetime of Mn2+ increases upon increasing the Cl- content. The former is due to the different thermal quenching for different coordinations of Mn2+ with Cl- and Br-, while the latter is due to the weaker spin-orbit coupling of the Mn2+ ion caused by the interaction with the lighter Cl- ions, which makes the spin selection rule stricter and leads to a longer lifetime of Mn2+ consequently.