Homogeneous and inhomogeneous broadening in single perovskite nanocrystals investigated by micro-photoluminescence

Metal halides with perovskite crystalline structure have given rise to efficient optoelectronic and photonic devices.In the present work, we have studied the light emission properties of single CsPbBr 3 and CsPbI 3 semiconductor perovskite nanocrystals (PNCs), as the basis for a statistical analysis of micro-photoluminescence (micro-PL) spectra measured on tens of them.At room temperature, the linewidth extracted from PL spectra acquired in dense films of these nanocrystals is not very different from that of micro-PL measured in single nanocrystals.This means that the homogeneous linewidth due to exciton-phonon interaction is comparable or larger than the inhomogeneous effect associated to the micro-PL peak energy dispersion due to the nanocrystal size distribution defined by the chemical synthesis of the PNCs.Contrarily, we observe very narrow micro-PL lines in CsPbBr 3 and CsPbI 3 PNCs at 4 K, in the range of 1-5 meV and 0.1-0.5 meV, respectively, because they are limited by spectral diffusion.Aging of PNCs under ambient conditions has been also studied by micro-PL and a clear reduction of their nanocube edge size in the order of the nm/day is deduced.