Recent Advances in Lanthanide‐Doped Perovskite Nanocrystals

Abstract This review provides a comprehensive overview of recent advances in ligand engineering, synthesis strategies, optoelectronic characteristics, and potential applications of lanthanide (Ln)‐doped halide perovskite nanocrystals, emphasizing their impact on material performance. The review begins by elucidating the crystal structure of halide perovskite nanocrystals, with an in‐depth analysis of how octahedral coordination and tolerance factors modulate structural stability. The unique optoelectronic advantages of Ln ions are emphasized, particularly their ability to facilitate energy transfer and f‐f electronic transitions, attributed to their distinctive electronic configurations and abundant energy level structures. The review then examines the impact of ligand selection on the nucleation, growth, and doping uniformity of Ln‐doped perovskite nanocrystals. Various synthesis strategies, including hot injection, ligand‐assisted reprecipitation, and ion exchange synthesis, are discussed, highlighting their respective advantages, limitations, and implications for practical applications. Additionally, the review provides a detailed discussion of how Ln doping enhances upconversion, downconversion, and quantum‐cutting emissions through efficient energy transfer mechanisms, thereby improving stability and luminescence efficiency. The outlook emphasizes future research directions, including the design of novel ligand structures for enhanced surface passivation, the development of strategies to improve environmental stability, and deeper investigations into luminescence mechanisms to enable superior performance in optoelectronic applications.