All‐Inorganic Rare‐Earth‐Based Double Perovskite Nanocrystals with Near‐Infrared Emission
Ruixiang Wu, Peigeng Han, Daoyuan Zheng, Junfeng Zhang, Songqiu Yang, Yang Zhao, Xiangyang Miao, Keli Han
Abstract
Abstract Lead‐free halide perovskite nanocrystals (NCs) with the unique optical properties are of interest for broad applications. There are a few studies on near‐infrared (NIR) emission in perovskite NCs. Here, all‐inorganic rare‐earth‐based Cs 2 NaEr 1− x B x Cl 6 (B: In, Sb, or Bi; x = 0, 0.13, and 0.5) double perovskite (DP) NCs have been successfully sythesized. The Cs 2 NaErCl 6 NCs show good air stability and emit a sharp NIR photoluminescence (PL) at telecommunication wavelength of 1543 nm, originating from 4 I 13/2 → 4 I 15/2 transition of the Er 3+ , and its average lifetime is 35.7 µs. Especially for Cs 2 NaEr 0.5 Sb 0.5 Cl 6 NCs, NIR PL can be enhanced 23‐fold with the lifetime being 119.1 µs. Moreover, femtosecond transient absorption measurements prove that a long‐lifetime trap state promotes NIR emitting in the mixed Sb/Er DP NCs.