Simultaneous Enhancement of the Luminescence Intensity and Stability of Deep-Red CsPbI₃ Perovskite Quantum Dots...

The phase instability of CsPbI₃ perovskite quantum dots (PQDs) restricts their practical applications due to the easy conversion from the luminescent cubic phase to the non-luminescent orthorhombic phase. The elemental doping route has been regarded as one of the most effective strategies to achieve high-quality PQDs-based phosphors. Herein, a stoichiometric amount of nickel chloride (NiCl₂) has been effectively doped into the CsPbI₃ lattice. The incorporation of Ni²⁺ ions has little effect on the crystal phase, structure, and morphology of the CsPbI₃ PQDs but greatly influences their luminescence properties. The Ni²⁺ doping not only improves the luminescence performance but also greatly enhances the stability against temperature, storage time, and polar solvent. The formation process and luminescence and stability improvement mechanisms have been discussed. Moreover, the influence of a series of other metal chlorides (KCl, NaCl, MgCl₂, ZnCl₂, SnCl₂, and CaCl₂) on the luminescence performance of CsPbI₃ PQDs has been systematically investigated, revealing that the luminescence intensity increases by introducing CaCl₂, SnCl₂, or ZnCl₂ but decreases after doping MgCl₂, NaCl, or KCl into the CsPbI₃ lattice. The as-proposed doping strategy may have a significant impact on tackling the intrinsic instability of all-inorganic CsPbX₃ PQDs, shedding light on their future applications in light-emitting diode (LED) devices and solid-state lighting.