Synthesis and Near-Infrared Emission of Yb-Doped Cs₂AgInCl₆ Double Perovskite Microcrystals and Nanocrystals

Abstract

Cs2AgInCl6 double perovskite (DP) is a direct band gap, stable, and environmentally benign material with a three-dimensional perovskite structure. However, the band gap (∼3.3 eV) is too wide for optoelectronic applications in the near-infrared (NIR) region. To achieve optical functionality in the NIR window, we have doped Yb3+ in both microcrystals and colloidal nanocrystals of Cs2AgInCl6 DPs. Our Yb-doped Cs2AgInCl6 DP microcrystals and nanocrystals show NIR emission at ∼994 nm (1.24 eV), whereas the band gap of the hosts is in the UV region. Therefore, the Yb-emission does not suffer from self-absorption. The microcrystals exhibit a single-exponential decay with 2.7 ms long lifetime corresponding to 2F5/2 → 2F7/2 transition of Yb3+ f electrons. The nanocrystals show biexponential decay (3 ms and 749 μs), probably because of the proximity of Yb to the surface of nanocrystals. Interestingly, NIR emission and perovskite structure of samples are stable for >3 months in ambient conditions for future optoelectronic applications.

Lanthanide doping in metal halide perovskite nanocrystals: spectral shifting, quantum cutting and optoelectronic applications

“…Gamelin and coworkers found that the acetate salt of Yb 3+ (Yb(CH 3 COO) 3 •xH 2 O) could achieve higher solubility in organic solvents at high temperature compared to the YbCl 3 •6H 2 O precursor 22 . Likewise, acetate or nitrate precursors of Ln 3+ have been used to dope lead-free metal halide double perovskite NCs 29,30 . However, easy and flexible Ln 3+ doping in narrower band gap hosts, such as CsPbBr 3 and CsPbI 3 NCs, is challenging.…”

Recent Developments in Lead‐Free Double Perovskites: Structure, Doping, and Applications

“…After doping of the transition metal into LFDP,s everalg roups have reported rare-earth doping. [19,39] Quantum-cutting luminescenceh as been reported for CsPbCl 3 doped with heterovalent rare-earth elementY b 3 + . [40] In this work, it was hypothesized that the formationo ft he complex of Yb 3 + -V Pb -Yb 3 + assisting quantum-cutting luminescence and shares the excitation energy to two neighbored Yb 3 + ions.…”

“…For the Cs 2 AgInCl 6 NCs, two types of emission states were also resolved, that is, one at 350 nm because of band edge emission and another at 395 nm owing to the defective state emission. Recently, Mahor et al . studied the Yb doped Cs 2 AgInCl 6 for nano and microcrystal complex.…”

Recent Advances and Optoelectronic Applications of Lead‐Free Halide Double Perovskites

“…adopted Cs 2 NaBiCl 6 as the host for Mn 2+ doping and the bulk Mn 2+ ‐doped candidate showed a high PLQY of about 15 % with an orange–red emission color [43] . In terms of the f–f transition, the Yb 3+ ‐doped Cs 2 AgBiX 6 (X=Cl, Br) NCs exhibit a near‐infrared emission at 1000 nm, [83] which is also observed in Cs 2 AgInCl 6 [84] . Moreover, the Ho 3+ ‐doped Cs 2 (Na, Ag)InCl 6 LED devices exhibit dual emission, including warm white emission and the effective characteristic emission of Ho 3+ in the visible region [85] …”