Fluorescent Alloy CsPbxMn1-x,I3 Perovskite Nanocrystals with High Structural and Optica Stability

CsPbI3 nanocrystals are still limited in their use because of their phase instability as they degrade into the yellow nonemitting delta-CsPbI3 phase within a few days. We show that alloyed CsPbxMN1-x,I-3 nanocrystals have essentially the same optical features and crystal structure as the parent a-CsPbI3 system, but they are stable in films and in solution for periods over a month. The stabilization stems from a small decrease in the lattice parameters slightly increasing the Goldsmith tolerance factor, combined with an increase in the cohesive energy. Finally, hybrid density functional calculations confirm that the Mn2+ levels fall within the conduction band, thus not strongly altering the optical properties.