Efficient and stable CsPbBr3 perovskite quantum dots by dodecyl dimethyl betaine ligand toward light-emitting diode

Lead halide perovskite quantum dots (PeQDs) have shown great potential for applications in light-emitting diodes (LEDs) due to their exceptional optoelectronic properties. However, the highly dynamic binding of conventional oleic acid (OA) and oleylamine (OAm) ligands to the surface of PeQDs significantly compromises their photoelectric properties and stability, which adversely affects the electroluminescence (EL) performance. Here, dodecyl dimethyl betaine (BS12), a ligand that can strongly bind to the PeQD surface, is introduced to stabilize the dynamic surface and passivate the surface defects of PeQDs. Experimental results and density functional theory calculations demonstrate that BS12 treatment can partially replace the dynamically bound OA/OAm ligands due to strong binding ability, significantly reducing surface defects in solution status and thus leading to more than a twofold increase in photoluminescence quantum yield. Furthermore, BS12 treatment enables improved film-forming ability, carrier transporting capacity, lower trap density, and enhanced film stability. Consequently, the EL performance of PeQD LEDs is markedly improved, especially with a 720% increase in operational lifetime. This work presents a promising strategy for synthesizing high-performance PeQDs.