Lead Halide Perovskite Quantum Dots Capped by Glycyrrhizic Acid for White-Emitting LEDs

Lead halide perovskite quantum dots (PeQDs) have promising research prospects in light-emitting diodes (LEDs), yet their instability in polar environments hinders practical implementation. In this work, we employ the amphiphilic ligand glycyrrhizic acid (GA) as a sole surface modifier to passivate PeQDs. Combined experimental and density functional theory (DFT) results reveal that GA strongly coordinates with unsaturated Pb sites on the perovskite surface through multidentate chelation, effectively suppressing surface defects in solution and enhancing photoluminescence efficiency and stability in polar solvents. Owing to its unique amphiphilic nature, GA enables CsPbBr3 PeQDs to achieve a high photoluminescence quantum yield (PLQY) of up to 83% in the polar solvent ethanol. Specifically, the GA-PeQDs retained ∼79% of its initial PL intensity after 360 days of storage in ethanol, underscoring their outstanding long-term colloidal and optical stability. Temperature-dependent photoluminescence spectra further confirm that the improved optical performance and stability originate from a higher activation barrier for thermally activated nonradiative recombination, indicating that GA passivation effectively suppresses thermally activated trap-assisted recombination. Finally, we fabricate a high-performance white LED with Commission Internationale de l’Eclairage (CIE) coordinates of (0.32, 0.35) by integrating the as-prepared PeQDs. This work offers a practical ligand-based strategy for obtaining efficient and stable perovskite quantum dots toward advanced photophysical applications.