Zn ²⁺ -Doping Assisted Preparation for Efficient Pure Red CsPbI ₃ Nanocrystals with Narrow Emission

CsPbI 3 perovskite nanocrystals (NCs) are emerged as promising materials for optoelectronic devices because of their superior optical properties. However, the brightness of the deep red fluorescence does not satisfy the requirements of outdoor displays. Herein, we report an effective strategy of Zn 2+ -assisted passivation to obtain pure red fluorescence and narrow emission CsPbI 3 NCs at a modified hot-injection method. It is found that the introduced Zn 2+ ions are successfully doped into the NCs lattice to replace some Pb 2+ ions for passivating some defects, increasing the radiative recombination rate and decreasing the nonradiative recombination rate. As a result, the as-prepared Zn 2+ -treated CsPbI 3 (Zn-CsPbI 3 ) have a luminescence peak position at 635 nm and narrow full width at half maximum of only 29.8 nm, with photoluminescence quantum yield (PLQY) up to 81%, which is 30% higher than the pristine NCs. Meanwhile, the structure of the Zn-CsPbI 3 NCs is orthorhombic (γ) phases, and their morphology is a uniformly distributed hexagonal crystal system.