Homogeneous and inhomogeneous broadening in single perovskite nanocrystals investigated by micro-photoluminescence
Hamid Pashaei Adl, Setatira Gorji, Guillermo Muñoz‐Matutano, Raúl Iván Sánchez Alarcón, Rafael Abargues, Andrés F. Gualdrón‐Reyes, Iván Mora‐Seró, Juan P. Martínez‐Pastor
Abstract
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.