Ligand engineering for blue-emitting reduced-dimensional perovskites

Perovskite light-emitting diodes (PeLEDs) are promising candidates for next-generation displays and lighting technology, owing to their high color purity, precisely tunable emission colors, and extremely low material and fabrication costs. However, blue PeLEDs face challenges such as low efficiency, poor stability, and severe phase separation compared to their red and green counterparts. Low-dimensional perovskites, with their wide bandgap and excellent stability, hold great promise for fabricating high-performance blue devices. In this material system, organic spacer ammonium cations (i.e., organic ligands) not only serve as key structural components but also enable molecular-level modulation of material properties. This review systematically summarizes recent research progress in ligand engineering for blue-emitting low-dimensional perovskites. From the perspectives of ligand types, design and application strategies, and underlying mechanisms, we provide an in-depth discussion of the intrinsic “ligand-structure-performance” relationships and offer an outlook on future research directions.