Lead halide perovskite nanocrystals (LHP NCs) have garnered significant attention due to their unique optical and structural properties, making them promising candidates for various optoelectronic applications. These nanocrystals, such as CH₃NH₃PbX₃ (MAPbX₃) and CsPbX₃, exhibit tunable emission across the visible and near-infrared spectrum, high photoluminescence quantum yields (PL QYs), and defect tolerance, which allows them to function as bright emitters without surface passivation. However, their stability under environmental conditions remains a challenge, as they are prone to degradation due to moisture, oxygen, and light exposure. To address this, researchers have explored various synthetic strategies, including the use of different ligands, core-shell structures, and protective coatings, to enhance the stability and photostability of LHP NCs. The defect tolerance of LHP NCs is attributed to their ionic bonding and the ability to maintain a clean bandgap despite structural defects. This property is crucial for their performance in optoelectronic devices. Additionally, the use of mixed-cation perovskites, such as CsPbI₃ and FAPbI₃, has been shown to improve stability and reduce the "red wall" issue, which refers to the difficulty in obtaining stable NCs with emission in the red and near-infrared regions. The Goldschmidt tolerance factor (TF) plays a key role in determining the stability of these materials, with TF values indicating the compatibility of cations and anions in the lattice. Recent advances in the synthesis of LHP NCs have focused on improving their stability through various methods, including the use of silica or silicone derivative coatings, polymer-based passivation, and the formation of core-shell structures. These strategies have led to the development of highly stable LHP NCs with enhanced photostability and emission properties. Furthermore, the tunability of perovskite NC compositions through anion exchange has enabled the creation of a wide range of color gamuts, making them suitable for applications in backlighting and color conversion in liquid-crystal displays. Despite these advancements, challenges remain in achieving long-term stability and preventing degradation under various environmental conditions. Future research will focus on optimizing the synthesis and passivation strategies to enhance the performance and reliability of LHP NCs in optoelectronic applications. The potential of LHP NCs as a competitive alternative to traditional colloidal quantum dots in applications such as backlit TV displays and color-conversion layers is promising, given their high PL QYs, narrow emission linewidths, and tunable emission properties.Lead halide perovskite nanocrystals (LHP NCs) have garnered significant attention due to their unique optical and structural properties, making them promising candidates for various optoelectronic applications. These nanocrystals, such as CH₃NH₃PbX₃ (MAPbX₃) and CsPbX₃, exhibit tunable emission across the visible and near-infrared spectrum, high photoluminescence quantum yields (PL QYs), and defect tolerance, which allows them to function as bright emitters without surface passivation. However, their stability under environmental conditions remains a challenge, as they are prone to degradation due to moisture, oxygen, and light exposure. To address this, researchers have explored various synthetic strategies, including the use of different ligands, core-shell structures, and protective coatings, to enhance the stability and photostability of LHP NCs. The defect tolerance of LHP NCs is attributed to their ionic bonding and the ability to maintain a clean bandgap despite structural defects. This property is crucial for their performance in optoelectronic devices. Additionally, the use of mixed-cation perovskites, such as CsPbI₃ and FAPbI₃, has been shown to improve stability and reduce the "red wall" issue, which refers to the difficulty in obtaining stable NCs with emission in the red and near-infrared regions. The Goldschmidt tolerance factor (TF) plays a key role in determining the stability of these materials, with TF values indicating the compatibility of cations and anions in the lattice. Recent advances in the synthesis of LHP NCs have focused on improving their stability through various methods, including the use of silica or silicone derivative coatings, polymer-based passivation, and the formation of core-shell structures. These strategies have led to the development of highly stable LHP NCs with enhanced photostability and emission properties. Furthermore, the tunability of perovskite NC compositions through anion exchange has enabled the creation of a wide range of color gamuts, making them suitable for applications in backlighting and color conversion in liquid-crystal displays. Despite these advancements, challenges remain in achieving long-term stability and preventing degradation under various environmental conditions. Future research will focus on optimizing the synthesis and passivation strategies to enhance the performance and reliability of LHP NCs in optoelectronic applications. The potential of LHP NCs as a competitive alternative to traditional colloidal quantum dots in applications such as backlit TV displays and color-conversion layers is promising, given their high PL QYs, narrow emission linewidths, and tunable emission properties.