Boosting Near‐Infrared Luminescence of Lanthanide in Cs 2 AgBiCl 6 Double Perovskites via Breakdown of the Local Site Symmetry

• Published in: Angewandte Chemie 2022-07, Vol.134 (30)
• Main Authors: Pei, Yifan, Tu, Datao, Li, Chenliang, Han, Siyuan, Xie, Zhi, Wen, Fei, Wang, Luping, Chen, Xueyuan
• Format: Article
• Language: English
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202205276

Currently, lanthanide (Ln 3+ )‐doped near‐infrared (NIR)‐emitting double perovskites (DPs) suffer from low photoluminescence quantum yield (PLQY). Herein, we develop a new class of NIR‐emitting DPs based on Ln 3+ ‐doped Cs 2 (Na/Ag)BiCl 6 . Benefiting from the Na + ‐induced breakdown of local site symmetry in the Cs 2 AgBiCl 6 DPs, effective NIR emissions of Ln 3+ are realized through Bi 3+ sensitization. Specifically, 7.3‐fold and 362.9‐fold enhanced NIR emissions of Yb 3+ and Er 3+ are achieved in Cs 2 Ag 0.2 Na 0.8 BiCl 6 DPs relative to those in Na‐free Cs 2 AgBiCl 6 counterparts, respectively. The optimal absolute NIR PLQYs for Yb 3+ and Er 3+ in Cs 2 Ag 0.2 Na 0.8 BiCl 6 DPs are determined to be 19.0 % and 4.3 %, respectively. Raman spectroscopy and first‐principles density functional theory calculations verify the sublattice distortion in Cs 2 (Na/Ag)BiCl 6 DPs via Na + doping. These findings provide fundamental insights into the design of efficient NIR‐emitting Ln 3+ ‐doped DPs for versatile optoelectronic applications.