Highly stable blue fluorescent lead free all-inorganic Cs2ZnX4 2D perovskite nanocrystals

Lead toxicity and instability both are the big concern for the utilization of lead halide perovskites. To defeat this challenge, we synthesized lead free Zn based all inorganic mixed halide 2D perovskite Cs2ZnX4 (X = Cl4, Cl2Br2 and Cl2I2) nanocrystals (PNCs) first time with high photoluminescence quantum yield of 51.93%. Perovskite NCs were synthesized by using ligand-assisted re-precipitation (LARP) technique at 80 °C with the pH = 8.4 of reaction solution. The formation of Cs2ZnCl4, Cs2ZnBr2Cl2 and Cs2ZnCl2I2 NCs was discussed in details. We have observed tenability of their optical band gap from 3.68 to 3.54 eV. These blue fluorescent NCs displayed morphological change from hexagonal to quasi-spherical and maintained their excellent stability over six months. The as-prepared NCs were characterized by using UV–vis, PL, XRD, TEM, FE-SEM, EDS, TCSPC, Raman, FT-IR, XPS and TGA analytical techniques.