Short-chain ligand synthesis of ytterbium-doped CsPbCl3 perovskite nanocrystals

Synthesis of lanthanide-doped perovskite nanocrystals generally utilizes long-chain ligands like oleylamine and oleic acid at high temperatures up to 260 °C. To tackle this issue, we develop a strategy (temperatures down to 170 °C) to fabricate ytterbium (Yb³⁺)-doped CsPbCl₃ perovskite nanocrystals using the octylamine ligand benefited from its low boiling point and short carbon chain. The as-prepared Yb³⁺-doped CsPbCl₃ perovskite nanocrystals can yield both violet luminescence assigned to exciton recombination and near-infrared emission ascribed to Yb³⁺: ²F_5/2 → ²F_7/2. Structural and spectroscopic characterizations evidence that energy transfer from CsPbCl₃ to Yb³⁺ and from defect states to Yb³⁺ are simultaneously responsible for the observed Yb³⁺ luminescence with quantum yield of 49.5 %. Femtosecond transient absorption spectra confirm that the transferring time scale is within 100 ps, which is much faster than the photoluminescent decay lifetimes of 3000 ps, enabling efficient CsPbCl₃-to-Yb³⁺ energy transfer and thus Yb³⁺ luminescence.