All‐Inorganic Rare‐Earth‐Based Double Perovskite Nanocrystals with Near‐Infrared Emission

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 Cs2NaEr1−xBxCl6 (B: In, Sb, or Bi; x = 0, 0.13, and 0.5) double perovskite (DP) NCs have been successfully sythesized. The Cs2NaErCl6 NCs show good air stability and emit a sharp NIR photoluminescence (PL) at telecommunication wavelength of 1543 nm, originating from 4I13/2→4I15/2 transition of the Er3+, and its average lifetime is 35.7 µs. Especially for Cs2NaEr0.5Sb0.5Cl6 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.

Dopant and Compositional Modulation Triggered Broadband and Tunable Near-Infrared Emission in Cs2Ag1–xNaxInCl6:Cr3+ Nanocrystals

“…In addition, doping lanthanide ions in lead-free metal halide perovskite NCs is another effective strategy for achieving NIR emission. For instance, the doping of Yb 3+ can endow Cs 2 AgBiX 6 (X = Cl – or Br – ) and Cs 2 AgInCl 6 NCs with NIR emission around 980 nm, which is ascribed to the 2 F 5/2 → 2 F 7/2 transition of Yb 3+ ; , Cs 2 NaErCl 6 and Er 3+ -doped Cs 2 AgInCl 6 exhibit NIR emission centered at 1540 nm due to the 4 I 13/2 → 4 I 15/2 transition. , However, these previous efforts all focus on narrowband NIR emission, while the broadband NIR emitters with greater application potential such as in 3D sensing and food analyzing are rarely mentioned but are essential for the applications. Meanwhile, the tunability of the emission spectra that are equally important in NIR applications has not yet been achieved in such lead-free perovskite NCs.…”

Manganese Ion‐Sensitized Near‐Infrared Light in Cs2NaBi1−xErxCl6 Lead‐Free Double Perovskite

“…The long ms‐scale lifetime is attributed to Er 3+ forbidden 4 I 13/2 → 4 I 15/2 transitions. These preliminary results suggest Er 3+ ions are well‐incorporated inside the host lattice [ 13,18 ] and the existence of energy transfer from Mn 2+ to Er 3+ .…”

Review for Rare-Earth-Modified Perovskite Materials and Optoelectronic Applications

“…Recently, Miao and Han et al doped Er 3+ ions into the lead-free Cs 2 NaEr 1-x B x Cl 6 (B is In, Sb or Bi) perovskite NCs, thus, to obtain effective NIR emission at a telecommunication wavelength of 1543 nm. Such NIR emission can be mainly attributed to the energy transition from 4 I 13/2 → 4 I 15/2 to Er 3+ [ 74 ]. Recently, ultrasmall CsPbX 3 QDs formed on the surface of NaYF 4 :Yb/Tm@NaYF 4 :Yb core-shell UCNPs (see in Figure 6 e) and could exhibit tunable down-conversion PL and up-conversion PL under UV and NIR excitation, respectively, which can be potentially applied in the field of fluorescent anticounterfeiting technology [ 75 ].…”