Spectral Characteristics of Mechanochemically Prepared Perovskite CH3NH3PbBr3 Nanoparticles Passivated by Amines with Different Alkyl Chain Length

We are the first to establish that the introduction of a small amount of passivating amine (Am) during the preparation of CH3NH3PbBr3 (MAPbBr(3)) (MA/Am = 0.7) leads to the formation of pseudo-2D nanoparticles of this hybrid perovskite, the number of layers in which decreases going from oleylamine to hexylamine. The use of a solution of polystyrene in toluene yields more homogeneous in size stabilized MAPbBr(3) nanoparticles and alters the number of layers in them. The resultant MAPbBr(3) dispersions and films have strong photoluminescence (PL), whose maximum is shifted toward higher energies in comparison with a powder of this hybrid perovskite due to a quantum size effect. Dispersions and films of MAPbBr(3) prepared using oleylamine have the highest PL quantum yield (about 90%) due to the formation of 2D nanoparticles with >= 4 layers. An advantage of the MAPbBr(3) samples prepared using hexylamine is increased color purity of the PL.