Influence of aliphatic hydrophobic side-chain amino acids on the stability of perovskite quantum dots

Organic–inorganic hybrid perovskite quantum dots are considered ideal materials for quantum dot light-emitting diodes (QLEDs) due to their outstanding optoelectronic properties. However, stability issues have hindered the commercial application of QLEDs. Reducing surface defects in perovskite quantum dots can enhance their stability and luminescent performance. The three amino acids with specific side-chain groups selected for this study (alanine, valine, and methionine) primarily achieve synergistic passivation through electrostatic-spatial hindrance complementarity synergistic effect and backbone-side-chain synergistic effect to anchoring defects such as vacancy defects and interstitial atoms in perovskite quantum dots, elucidating the impact of this synergistic effect on the stability of perovskite quantum dots. The optimal amino acid loading was determined via photoluminescence (PL) and ultraviolet-visible (UV-Vis) absorption spectroscopy. Time-resolved spectroscopy demonstrated that introducing amino acid ligands successfully suppressed non-radiative recombination, reduced surface defects in the quantum dots, and increased carrier lifetime by 2–3 times. Furthermore, photostability and aqueous stability tests revealed that electrostatic complementary synergistic strong steric hindrance enhances the aqueous stability of perovskite quantum dots, while electrostatic complementary synergistic weak steric hindrance is more conducive to improving light stability.