A Phase Regulation Strategy of Ammonium Ions Perovskite Nanocrystals from 1D Orthomorphic NH4PbI3 to 3D Cubic Phase by Cs Ions to Notedly Enhance Photoluminescence.

Abstract

In this work, we firstly synthesized 1D orthogonal NH4PbI3 perovskite NCs with considering the role of inorganic ammonium ions at the nanoscale. It can be found that the addition of bromide ions at the halogen site cannot improve the photoluminescence properties. Furthermore, we successfully synthesized 3D cubic phase of (NH4)0.5Cs0.5Pb(I0.5Br0.5)3 NCs with bright photoluminescence by adding Cs ions into the crystal lattice of (NH4)Pb(I0.5Br0.5)3. Moreover, the photophysical properties are obtained of different phase structures using femtosecond transient absorption (FTA) spectroscopy. The obvious ultrafast trap state capture process is a key factor in the change of photoluminescence properties and the cubic phase may be the best structure for photoluminescence. These results suggest that the ammonium ions perovskite (AIP) nanocrystals could be potential materials for optoelectronic applications through A-site cation substitution strategy.