Tailoring Substitutional Sites for Efficient Lanthanide Doping in Lead-Free Perovskite Nanocrystals with Enhanced Near-Infrared Photoluminescence
Hanjie Lin, Sara Talebi, Walker MacSwain, Vanshika Vanshika, Arindam Chakraborty, Weiwei Zheng
Abstract
High Resolution Image Download MS PowerPoint Slide The incorporation of rare earth lanthanide ions (Ln 3+ ) into lead-free halide perovskite nanocrystals (NCs) is an effective and promising strategy to expand their optical, magnetic, and electrochemical properties. Herein, we designed and synthesized various Ln 3+ (including Yb 3+, Er 3+, and Nd 3+ ), doped Sb 3+ - or Bi 3+ -based and Sb 3+ /Bi 3+ alloyed lead-free perovskite NCs, including vacancy-induced perovskite (A 3 B(III) 2 X 9 ), double perovskite (A 2 B(I)B (III)X 6 ), and layered-double perovskite (A 4 B(II)B(III) 2 X 12 ) NCs with different energy transfer pathways to study the Ln 3+ dopant photoluminescence (PL). While a small size mismatch between dopant ions and host substitutional sites are critical for efficient doping of many first-row transitional metal ion doped metal chalcogenides, surprisingly, the Ln 3+ ions, including the large Nd 3+ ions (112 pm), prefer smaller isovalent Sb(III) octahedral (O h ) sites (90 pm) instead of Bi(III) O h sites (117 pm) in these lead-free perovskite NCs. Significantly, similar substitutional site-dependent Ln 3+ doping efficiencies were obtained across all three different perovskite host lattices, despite differences in host-to-dopant energy transfer mechanisms, which can provide strong evidence of the preferred Sb 3+ substitutional sites for lanthanide dopants in these lead-free perovskite lattices. The efficient Ln 3+ doping in Sb 3+ -rich perovskite NCs leads to enhanced Ln 3+ ion PL of the doped NCs. The preference of smaller Sb (III) over Bi(III) substitutional sites for Ln 3+ dopants is attributed to the relatively high polarizabilities of lanthanide ions and the smaller cationic sites inside [SbX 6 ] 3– compared with [BiX 6 ] 3– octahedra. This study provides a fundamental understanding of Ln 3+ doping behavior in lead-free perovskite NCs and opportunities for designing efficient Ln 3+ -doped functional materials by tuning the microenvironment of the host lattice for enhanced properties.