Formamidinium-Based Quasi-2D Perovskite Nanoplates With Dimensionally Tuned Optical Properties

We report for the first time the synthesis of quasi-two-dimensional (2D) perovskite nanoplates by incorporating 2D TMA ₂ PbBr ₄ (C ₄ H ₉ NH ₃ , TMA) into formamidinium (FA) based 3D perovskite nanocrystals via the facile solution-processed method. In this way, we achieve morphology evolved quasi-2D perovskite TMA ₂ (FA) _n-1 PbnBr _{3 n+ 1} . The steady-state photoluminescence is blueshifted as the perovskite is dimensionally tuned from 3D to 2D, which is normally attributed to the structure relaxation. The optical properties of quasi-2D perovskite nanoplates can also be achieved by tuning the acidity of the reaction precursor. The proposed configuration and growth mechanism of quasi-2D TMA ₂ (FA)n _-1 PbnBr _3n+1 perovskite with different n values has been further confirmed by Raman spectroscopy. This study opens up opportunities for fundamental research on the synthesis and characterization of quasi-2D perovskite nanoplates and introduces a new family of quasi-2D solution-processed perovskites for optoelectronic devices.