In-situ synthesis of quaternary alkylammonium ligand capped organic-inorganic hybrid halide perovskite for high pure green luminescence in display application

This study delves into the intricate dynamics of ligand engineering for the synthesis of Methyl Ammonium Lead Bromide (MAPbBr₃) nanocrystals (NCs), which exhibit immense potential in optoelectronic and photovoltaic applications. Our focus centres on the role of the quaternary ammonium molecule CTAB as a ligand in stabilizing MAPbBr₃ NCs. This also addresses the challenges related to the stability and surface defects of NCs that hinder their commercial viability. Employing a modified ligand-assisted reprecipitation technique (LARP) with a dual solvent system, we optimized the CTAB concentration to 0.05 mmol, resulting in MAPbBr₃ NCs with an impressive 88% quantum yield. XPS and FTIR analyses confirm the presence and binding of CTAB on the NC surface. The MAPbBr₃-CTAB NCs exhibit higher exciton-phonon binding energy, enhancing their optical properties. Despite an unfavourable geometric fit, CTAB is effective in surface defect passivation due to its binding, solvation, and desorption energy during the dynamic binding process. 2D-DOSY NMR reveals approximately 66% CTAB bound to the NC surface. A comparative study involving MAPbBr₃-OA, OLA, and MAPbBr₃-CTAB deposited on LEDs demonstrates the superior performance of the latter, achieving a luminous efficiency of 42.18 lm W⁻¹ at 1.2 ml deposition. These findings highlight the efficacy of CTAB in achieving high-purity green luminescence, aligning with BT.2020 display colour standards and paving the way for advanced optoelectronic applications. The successful synthesis and improved performance of MAPbBr₃-CTAB NCs underscore their potential as a promising material for future optoelectronic and photovoltaic technologies.