IMPACT OF AZINE LIGAND ON THE OPTICAL AND MAGNETIC PROPERTIES OF CSPBIBR2 QUANTUM DOTS

Abstract

In this research, the synthesis and photophysical up-conversion properties of CsPbBr₂ quantum dots (QDs) are investigated, with a particular focus on the use of azine-based ligands to control their structural and optical properties. Utilizing a room-temperature, solvent-induced nucleation process with a polar solvent of dimethyl sulfoxide (DMSO) and a non-polar medium of toluene allowed for effective QD formation at ambient conditions, providing a scalable route in place of traditional hot-injection processes. Trimethylolmelamine was initially employed as a model ligand to illustrate the impact of surface passivation on QD morphology, colloidal stability, and optoelectronic performance. Azine ligand incorporation later drastically changed nucleation dynamics, leading to enhanced monodispersity, increased crystallinity, and even better environmental stability. Ligand-induced bandgap tuning via UV-Visible spectroscopy showed shifts in absorption edges, while FTIR spectroscopy evidenced successful coordination of ligands through characteristic vibrational modes. DFT calculations further explained ligand binding effects on surface energetics, trap state suppression, and electronic band structure. Visual indicators, including clear color changes during synthesis, corroborated QD formation, and optical analyses upheld enhanced photoluminescence efficiency and reduced non-radiative recombination. These results highlight the key role of surface ligand chemistry in the modulation of perovskite QD properties and stability, making way for their use in high-performance optoelectronic devices—such as LEDs, bioimaging, and photon up-conversion systems—with special promise in facilitating phosphorescence and long-lived excitonic states by the rational design of ligands.