Perovskite Nanocrystals Synthesis: Exploring different approaches and ligand influence: A Review

Abstract

Metal halide perovskite nanocrystals (NCs) have emerged as highly promising materials for next-generation optoelectronic, photovoltaic, sensing, and energy-related applications owing to their remarkable optical and electronic properties. These properties include tunable bandgaps, high absorption coefficients, efficient charge-carrier transport, long carrier diffusion lengths, strong light absorption, and high photoluminescence quantum yields. Their unique compositional and structural flexibility also enables their optical and electronic properties to be tailored for specific technological applications. Despite these advantages, the practical utilization of perovskite nanocrystals remains limited by several challenges, including surface defects, ion migration, poor environmental stability, ligand instability, and degradation under exposure to moisture, oxygen, heat, intense illumination, and electrical stress. In this regard, surface capping ligands play a fundamental role in controlling the nucleation and growth of perovskite nanocrystals and in regulating their surface chemistry, morphology, crystallinity, optical properties, and colloidal stability. This review presents a comprehensive assessment of recent advances in the design, synthesis, characterization, and application of ligand-capped metal halide perovskite nanocrystals. Particular emphasis is placed on the roles of conventional organic ligands, inorganic ligands, polymers, and emerging bio-derived ligands in controlling nanocrystal size and shape, reducing surface defects, improving charge-carrier dynamics, and enhancing photoluminescence efficiency and stability. Furthermore, recent developments in understanding ligand binding mechanisms, surface chemistry, ligand–nanocrystal interactions, and dynamic surface reconstruction are critically discussed. Strategies including ligand exchange, ligand engineering, controlled ligand density, surface passivation, and cross-linking are examined as approaches for improving charge transport, resistance to environmental degradation, and overall device performance while minimizing the formation of insulating surface layers. Particular attention is also given to the emerging use of sustainable and naturally derived bioligands as environmentally friendly alternatives to conventional synthetic surface modifiers.Despite significant progress, challenges associated with ligand loss, surface reconstruction, reproducibility, toxicity, processing compatibility, and large-scale synthesis remain unresolved. Overall, a deeper understanding and precise control of ligand–nanocrystal interactions are essential for developing highly stable, efficient, and environmentally sustainable perovskite nanocrystals. Continued advances in ligand engineering are therefore expected to facilitate the broader integration of these materials into light-emitting diodes, solar cells, photodetectors, sensors, photocatalytic systems, and other advanced optoelectronic and energy-conversion technologies.