Short-chain ligand engineering toward room-temperature synthesis of high-brightness CsPbBr₃ nanocrystals for color-conversion LED applications

The labile nature of conventional long-chain ligands on CsPbBr₃ quantum dots (QDs) often leads to desorption during device fabrication, creating surface traps that compromise efficiency and stability. Here, we employ a supersaturation-precipitation method at room temperature, introducing 4-bromobutyric acid (BA) as a short-chain co-ligand alongside conventional oleic acid (OA) and oleylamine (OAm). The BA ligand anchors to surface Pb²⁺ via its carboxyl group, while its terminal Br⁻ effectively fills surface Br vacancies. The combination of BA and OA enhances the photoluminescence quantum yield (PLQY) to 84.96% and improves stability. density functional theory (DFT) calculations were performed on CsPbBr₃-OA, CsPbBr₃-BA and CsPbBr₃-OA/BA QDs to analyze charge density difference, density of states, and binding energy, demonstrating that BA can passivate surface defects, thereby enhancing the stability and photoluminescence (PL) performance of the materials. Single-particle spectroscopy shows that BA ligand engineering narrows the emission linewidth and prolongs the dephasing time of CsPbBr₃ QDs, evidencing reduced local disorder and enhanced excitonic coherence. Coupled with a commercial 365 nm UV chip, green LED based on CsPbBr₃-OA/BA QDs emits 1.42 times the PL intensity of CsPbBr₃-OA ’s LED at 2.7 V. This work establishes short-chain ligands as an effective strategy to simultaneously achieve high efficiency and operational stability in perovskite QDs optoelectronics.