Facile Microwave Synthesis of a Narrow-Band Green-Emitting Phosphor Cs<sub>3</sub>MnBr<sub>5</sub> and the Effect of Anion Substitution on Its Luminescence Properties
Yingfang Tao, Haixing Zhao, Yan Xu, Deyin Wang, Yuhua Wang
Abstract
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.