Facile solution synthesis of Bi3+/Yb3+ ions co-doped Cs2Na0.6Ag0.4InCl6 double perovskites with near-infrared emission

Abstract

Double perovskites have attracted wide attention due to their low toxicity and good thermal stability. Doping with active elements is a promising method to endow perovskites with excellent optical, electrical or magnetic properties. Herein, a facile aqueous solution method is developed to synthesize Bi³⁺–Yb³⁺ co-doped Cs₂Na_0.6Ag_0.4InCl₆ double perovskite. Besides the intrinsic warm white self-trapped exciton (STE) emission that originated from the Cs₂Na_0.6Ag_0.4InCl₆ host, the samples also exhibit a strong near-infrared emission assigned to the ²F_5/2 → ²F_7/2 transition of octahedral coordinated Yb³⁺ ions upon excitation with ultraviolet light. The optimized sample shows a markedly high photoluminescence quantum yield of 84.7%. The photophysical studies such as photoluminescence (PL) and photoluminescence excitation spectra, temperature-dependent PL spectra, and PL decay curves reveal that the strong Yb³⁺ emission is attributed to the energy transfer from STEs to the Yb³⁺ ions. Finally, the lead-free double perovskite phosphor-converted LED containing visible and NIR regions was fabricated, with 8.92 mW output power at 100 mA drive current. The results show the great potential of the as-prepared crystals in optoelectronics applications.