DOI: https://doi.org/10.36347/sjpms.2025.v12i06.004

Pages: 226-239

Due to their outstanding optical features such as high PLQY, very narrow emission and the option to change their bandgap, inorganic cesium lead halide (CsPbX₃, X = Cl, Br, I) nanocrystals (NCs) have gotten much recognition. Nevertheless, environmental problems and the toxicity of lead have made it hard to use these compounds in lighting, solar energy and sensor technology for a long time. The authors propose that CsPbX₃/Cs₂SnX₆ (X = Cl, Br, I) core–shell perovskite nanocrystals treated with lead-free and twice-perovskite shells solve the aforementioned issues well. With density functional theory (DFT) and modeling of band alignment, we find that Cs₂SnX₆ has a cubic structure that is very similar to CsPbX₃, making it easy for the materials to bind together and maintain their crystalline nature. The construction of the energy band diagrams indicates that both Type I and Type II heterojunctions are present: enhancements to exciton confinement and photo-luminescence quantum yield occur for Type I in CsPbCl₃/Cs₂SnCl₆ and CsPbBr₃/Cs₂SnBr₆; while Type II alignment in CsPbI₃/Cs₂SnI₆ supports efficient electron and hole separation, so important for photovoltaics. According to the simulation results, core–shell structures increase the lifetime of the emitted light and it retains its ability to recombine quickly in normal air. More analyses prove that the Sn⁴⁺-shell protects the material from moisture, heat and light, so it serves well as an encapsulation material. Theoretical results on carrier behavior, lattice stability and resistance to surrounding conditions propose that CsPbX₃/Cs₂SnX₆ nanostructures could help produce much better, lead-free perovskite nanocrystals with better endurance and optoelectronic capabilities. With this framework, it is possible to develop advanced perovskite nanomaterials that enhance performance and are also sustainable.