High luminescence color gradient by physical mixing of two perovskite nanocrystals

Tunability in the optical properties of perovskite nanocrystals leads to tailoring of the morphology as well as the functionality of perovskite-based devices. Herein we report a new approach in which fine tunability in optical studies has been observed in samples P1 to P9 by systematic physical mixing of already prepared CH₃NH₃PbI₃ and CH₃NH₃PbBr₃ nanoparticles. CH₃NH₃PbI₃ and CH₃NH₃PbBr₃ have been synthesized in the presence of excess ligands, due to which the visible and fluorescence peaks are blue shifted. Later, we observed tunability in the fluorescence peaks of samples P1 to P9 covering the visible region from 450-600 nm. Morphological studies of all the samples have been performed using XRD, TEM and AFM analysis. XRD studies reveal that the phase changes from cubic to tetragonal on moving from sample P1 to P9 and the TEM morphology reveals the self-assembled spherical structures of all samples.