<p>Lead-free halide double perovskites have attracted significant attention owing to their eco-friendliness, structural tunability, and self-trapped exciton emission. Nevertheless, achieving efficient and stable near-infrared-II (NIR-II) luminescence, especially in materials incorporating lanthanide ions, remains a considerable challenge in photonics research. Herein, we report a notable advance in the design and synthesis of Sb<sup>3+</sup>-sensitized Cs<sub>2</sub>NaLuCl<sub>6</sub>:Er<sup>3+</sup> double perovskite single crystals, which exhibit an unprecedented external quantum efficiency of 45.3% for emission at 1542 nm. Sb<sup>3+</sup> acts as a broadband ultraviolet absorber and transfers energy to Er<sup>3+</sup> via self-trapped exciton emission. Moreover, at high concentrations of Er<sup>3+</sup>, Er<sup>3+</sup>-Er<sup>3+</sup> cross relaxation (<sup>2</sup>H<sub>11/2</sub> + <sup>4</sup>I<sub>15/2</sub> → <sup>4</sup>I<sub>9/2</sub> + <sup>4</sup>I<sub>13/2</sub>) selectively populates the NIR-emitting <sup>4</sup>I<sub>13/2</sub> state, suppressing competitive visible emission pathways. This synergistic host-sensitizer-activator design strategy, supported by density functional theory calculations, addresses long-standing efficiency limitations and opens new avenues for high-performance NIR-II emitters in bioimaging, night vision, and optical communications.</p>

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Cross-relaxation engineering in Sb3+-sensitized Cs2NaLuCl6:Er3+ double perovskites enabling a record 45.3% EQE in NIR-II luminescence

  • Jingheng Nie,
  • Chaohong Liao,
  • Huiwang Lian,
  • Renping Cao,
  • Sijie Liu,
  • Baoxia Liu,
  • Bang Lan,
  • Jing Wang

摘要

Lead-free halide double perovskites have attracted significant attention owing to their eco-friendliness, structural tunability, and self-trapped exciton emission. Nevertheless, achieving efficient and stable near-infrared-II (NIR-II) luminescence, especially in materials incorporating lanthanide ions, remains a considerable challenge in photonics research. Herein, we report a notable advance in the design and synthesis of Sb3+-sensitized Cs2NaLuCl6:Er3+ double perovskite single crystals, which exhibit an unprecedented external quantum efficiency of 45.3% for emission at 1542 nm. Sb3+ acts as a broadband ultraviolet absorber and transfers energy to Er3+ via self-trapped exciton emission. Moreover, at high concentrations of Er3+, Er3+-Er3+ cross relaxation (2H11/2 + 4I15/24I9/2 + 4I13/2) selectively populates the NIR-emitting 4I13/2 state, suppressing competitive visible emission pathways. This synergistic host-sensitizer-activator design strategy, supported by density functional theory calculations, addresses long-standing efficiency limitations and opens new avenues for high-performance NIR-II emitters in bioimaging, night vision, and optical communications.