Co-doping of Stibium and rare earth (Nd, Yb) in lead-free double perovskite for efficient near-infrared emission

A2BB’ X6 double perovskite has recently been considered as a potential substitute for lead-based halide perovskite. In particular, the lead-free Cs2AgInCl6 material possesses excellent moisture and thermal stability. However, the wide bandgap of the Cs2AgInCl6 host limits its optical properties. Doping with active elements is a unique avenue to endow Cs2AgInCl6 with excellent optical properties. Here, a strategy is proposed to explore the efficiency of near-infrared (NIR) emissions in Ln3+ (LnNd, Yb) ions doped Cs2AgInCl6 microcrystal by the codoping of Sb3+ ion for the first time. The incorporation of Sb3+ ion emerges a new optical absorption channel at a longer wavelength (>350 nm) and reduces the electron bandgap. Under the excitation at 365 nm, Sb3+ and Ln3+ (LnNd, Yb) co-doped Cs2AgInCl6 show the efficient NIR emission peaking at around 1000 nm, attributing to the effective energy transfer from Sb3+ to Yb3+ or Nd3+ f-electrons. Accordingly, the photoluminescence mechanism and environmental stability of Sb3+ and Ln3+ (LnNd, Yb) co-doped Cs2AgInCl6 microcrystal were also discussed in detail. This work demonstrates the availability of the Sb3+ doping tactics to realize efficient NIR emission in Ln3+ (LnNd, Yb) doped Cs2AgInCl6 microcrystal.