Advanced Luminescence Engineering of Inorganic Halide Perovskite Quantum Dots: Stability Enhancement, Lead-Free Design, and Optoelectronic Applications.

Inorganic halide perovskite quantum dots (IHPQDs), such as CsPbX3 (X = Cl, Br, I), have emerged as highly efficient luminescent nanomaterials owing to their outstanding photoluminescence quantum yields (up to 95%), narrow emission bandwidths, and tunable bandgaps across the visible spectrum. This review highlights recent advances in the luminescence engineering of IHPQDs, emphasizing synthesis strategies, surface passivation, and compositional control aimed at improving stability and reducing toxicity. The photophysical mechanisms governing quantum confinement, radiative recombination, and defect tolerance are discussed in detail, alongside their influence on luminescence efficiency and color purity. Key innovations-including silica encapsulation, phenethylamine ligand modification, Mn2+ doping, and fluorination-are analyzed as effective approaches to mitigate photodegradation and enhance long-term operational stability. Lead-free analogs such as Cs3Bi2Br9 and Cs3Sb2Br9 demonstrate promising blue emissions (PLQY up to 46%), offering eco-friendly alternatives for photonic and optoelectronic devices. Finally, this work outlines future directions for integrating IHPQDs into sustainable light-emitting, photovoltaic, and sensing systems, bridging the gap between laboratory-scale luminescent materials and scalable commercial technologies.