Incorporating Rare‐Earth Terbium(III) Ions into Cs₂AgInCl₆:Bi Nanocrystals toward Tunable Photoluminescence

Abstract

The incorporation of impurity ions or doping is a promising method for controlling the electronic and optical properties and the structural stability of halide perovskite nanocrystals (NCs). Herein, we establish relationships between rare‐earth ions doping and intrinsic emission of lead‐free double perovskite Cs2AgInCl6 NCs to impart and tune the optical performances in the visible light region. Tb3+ ions were incorporated into Cs2AgInCl6 NCs and occupied In3+ sites as verified by both crystallographic analyses and first‐principles calculations. Trace amounts of Bi doping endowed the characteristic emission (5D4→7F6‐3) of Tb3+ ions with a new excitation peak at 368 nm rather than the single characteristic excitation at 290 nm of Tb3+. By controlling Tb3+ ions concentration, the emission colors of Bi‐doped Cs2Ag(In1−xTbx)Cl6 NCs could be continuously tuned from green to orange, through the efficient energy‐transfer channel from self‐trapped excitons to Tb3+ ions. Our study provides the salient features of the material design of lead‐free perovskite NCs and to expand their luminescence applications.

Lead‐Free Halide Perovskites for Light Emission: Recent Advances and Perspectives

“…Their emissions could be adjusted from green light to orange light, which was ascribed to the energy transfer channel from self‐trapped excitons to Tb 3+ ions. [ 166 ] Upon Yb 3+ and Er 3+ doping, the emissions of 996 nm for Yb 3+ and 1537 nm for Er 3+ dopants were observed in Cs 2 AgInCl 6 nanocrystals. The introduction of these dopants expands the emission range and facilitates relevant luminescence applications, including optical communication, plant growth, and night‐vision devices.…”

Doping Lanthanide Ions in Colloidal Semiconductor Nanocrystals for Brighter Photoluminescence

“…119 Bound excitons can form at localized lattice defects/impurities that introduce interbandgap states just above the VB or below the CB. 56,64,120 The former can act as electron traps and the latter as hole traps -the two are also referred to as donor and acceptor levels, respectively. The recombination can therefore involve trapped and free charge carriers as shown in Figure 3B.…”

Lead‐Free Halide Double Perovskites: Structure, Luminescence, and Applications

“…Tb 3+ ‐doped Cs 2 NaInCl 6 : Bi 3+ NCs were first synthesized by hot injection. [ 177 ] Cs–OA (OA is the abbreviation for oleic acid) is swiftly injected into a clear precursor solution containing various stoichiometric ratios of AgNO 3 , InCl 3, and BiCl 3 and Tb(NO 3 ) 3 5H 2 O and Cs 2 NaInCl 6 :Bi 3+ NCs form immediately. Trace amounts of Bi doping introduce a new excitation peak at 368 nm rather than the single characteristic excitation at 290 nm of Tb 3+ .…”

“…The success confirms Bi doping is a general strategy to modify the excitation of HDPs to burst more efficient STEs or doped emission. [ 59,177 ] It should be noted that the efficiency of luminescence from RE dopants is still deficient compared to OIHPs, which may be due to the multistep carrier transport process from free excitons to dopants. So far, the highest PL QY of Yb 3+ ‐doped CsPb(Cl x Br 1‐ x ) 3 NCs can be over 190% with quantum cutting effect, while the most efficient NIR emission is from Cs 2 AgInCl 6 :Cr 3+ phosphor, with an absolute PL QY of 22%.…”