Effects of Zn Incorporation on Mn 2+ :CsPbCl x Br 3-x Nanocrystals for Enhanced Photoluminescence Quantum Yield

To enhance the photoluminescence quantum yield (PLQY), Zn 2+ /Mn 2+ co-doped CsPbCl 2.5 Br 0.5 nanocrystals (NCs) have been synthesized. As the Zn 2+ doping concentration increased in the Zn 2+ /Mn 2+ co-doped CsPbCl 2.5 Br 0.5 NCs, the emission peaks of the exciton and Mn 2+ showed only slight shifts. At a Pb:Mn:Zn feeding molar ratio of 1:2:0.5, Zn 2+ /Mn 2+ co-doped CsPbCl 2.5 Br 0.5 NCs exhibited a Mn 2+ to exciton emission intensity ratio of 31.4, and a PLQY of 85%. Variable-temperature photoluminescence (PL) spectroscopy showed that the exciton emission peak of Zn 2+ /Mn 2+ co-doped CsPbCl 2.5 Br 0.5 NCs exhibited negative thermal quenching as the temperature increased from 80 to 120 K. As the temperature increased from 80 to 300 K, the PL intensity ratio of Mn 2+ emission to exciton emission increased, and the Zn 2+ /Mn 2+ :CsPbCl 2.5 Br 0.5 NCs exhibited a higher ratio than the Mn 2+ :CsPbCl x Br 3-x NCs. Over the temperature range of 300-360 K, the Mn 2+ emission intensity of the Zn 2+ /Mn 2+ :CsPbCl 2.5 Br 0.5 NCs first decreased slightly and then returned to its original level. These results indicate that incorporating an appropriate concentration of Zn 2+ enhances Mn 2+ luminescence.