A 2 BB’ X 6 double perovskite has recently been considered as a potential substitute for lead-based halide perovskite . In particular, the lead-free Cs 2 AgInCl 6 material possesses excellent moisture and thermal stability. However, the wide bandgap of the Cs 2 AgInCl 6 host limits its optical properties . Doping with active elements is a unique avenue to endow Cs 2 AgInCl 6 with excellent optical properties . Here, a strategy is proposed to explore the efficiency of near-infrared (NIR) emissions in Ln 3+ (Ln Nd, Yb) ions doped Cs 2 AgInCl 6 microcrystal by the codoping of Sb 3+ ion for the first time. The incorporation of Sb 3+ ion emerges a new optical absorption channel at a longer wavelength (>350 nm) and reduces the electron bandgap. Under the excitation at 365 nm, Sb 3+ and Ln 3+ (Ln Nd, Yb) co-doped Cs 2 AgInCl 6 show the efficient NIR emission peaking at around 1000 nm, attributing to the effective energy transfer from Sb 3+ to Yb 3+ or Nd 3+ f-electrons. Accordingly, the photoluminescence mechanism and environmental stability of Sb 3+ and Ln 3+ (Ln Nd, Yb) co-doped Cs 2 AgInCl 6 microcrystal were also discussed in detail. This work demonstrates the availability of the Sb 3+ doping tactics to realize efficient NIR emission in Ln 3+ (Ln Nd, Yb) doped Cs 2 AgInCl 6 microcrystal.
Dingyi Shen,Yini Mao,Jun Yang,Lu Cao,Juntao Ning,Shanshan Hu
In this work, uniform and monodisperse Sr2YF7 spheres were successfully synthesized via a facile one-step hydrothermal route without employing any surfactant. Particularly, a well-defined morphology of Sr2YF7 crystals ranging from spherical to octahedral shape was first achieved by adjusting the pH values. In addition, the spherical products doped with 6% Ln3+ (Ln = La, Ce, Pr, Sm, Gd, and Dy) show different sizes ranging from 300 to 600 nm. The Sr2YF7 crystals also exhibit excellent multicolor DS/UC luminescence properties after doping with different Ln3+ ions. Energy transfer from Tb3+ to Eu3+ was observed in Sr2YF7 crystals; the Sr2YF7:Dy3+ crystals showed nearly white light emission under UV excitation; Sr2YF7:Yb3+/Er3+/Tm3+ crystals could produce pure white light with a CIE color coordinate of (0.3123, 0.3005) by controlling the doping concentrations of Er3+ and Tm3+ ions under 980 nm excitation. The as-prepared phosphors may potentially serve as light, color displays and markers in biological imaging.
The broad-band self-trapped exciton (STE) emission feature of lead-free halide double perovskites makes it challenging to realize emission with various wavelengths in a single material. Cs2NaInCl6:Sb3+ crystals with blue emission (440 nm) were synthesized by rationally introducing the Sb3+ ion into Cs2NaInCl6 with a photoluminescence quantum yield (PLQY) up to 99.35%. The Ln3+ (Tb3+ and Ho3+) ions were doped into Cs2NaInCl6:Sb3+ to achieve spectrally tunable emission from blue to green and pink emission owing to the energy transfer from the host STE to Ln3+ ions, with PLQY values of 90.68% and 61.87%, respectively. By carefully adjusting the doping level of Ln3+ ions, white light emission with a PLQY of 68.87% was achieved in the Tb3+ and Ho3+ co-doped Cs2NaInCl6:Sb3+ system. LED devices based on Sb3+/Ln3+ co-doped Cs2NaInCl6 with multicolor and white light emissions were fabricated based on these phosphors, which exhibit excellent spectral and environmental stability. The results show that double perovskite luminescence materials have potential for application in solid-state lighting and multi-color displays.
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