Emission of Mn2+ ions in Mn:CsPbX3 (x = Cl, Br, I) nanocrystals adjusted with halogen ion ratios

The photoluminescence (PL) of doped ions is depended strongly on the position of the ion in the substrate. Ion doping endows semiconductor nanocrystals with novel properties. In this paper, Mn:CsPb(Cl/Br)(3) nanocrystals (NCs) with different halogen ratios were obtained by one-pot hot injection synthesis and halogen ion exchange. The emission of Mn2+ from T-4(1g)-(6)A(1g) d-d transition was observed in the case of changing the molar ratio of Cl/Br for Mn:CsPb(Cl/Br)(3) NCs. In the case of a Cl/Br ratio of 4/1, the PL peak of perovskite became weak and Mn2+ emission was enhanced. After I- ion exchange, the emission of Mn2+ was observed in Mn:CsPb(Cl/Br)(3) with Cl/Br ratio of 1/4, in which the PL efficiency of the nanocrystals reached 55.74%. Thus, Cl- ions increase the band gap and effectively promote the emission of Mn2+. At the same time, the morphology of the samples after ion exchange always remains cube. The lifetimes of the nanocrystals were short aged with increasing Cl- ions and prolonged with increasing I- ions. Because these Mn:CsPbX3 (x = Cl, Br, I) NCs with different halogen ratios revealed highly stabile blue to red emission, the nanocrystals would be utilizable for further applications.