Highly Efficient White-Light Emission Triggered by Sb3+ Dopant in Indium-Based Double Perovskites

Inorganic indium-based halide double perovskites (DPs) are environmentally friendly alternatives to lead-based halide perovskites in light-emitting diodes, but commonly suffer from low quantum efficiency and harsh synthesis conditions. Herein, a large-scale green method using water as solvent is developed for the synthesis of 3D Cs 2 NaInCl 6 and 0D Cs 2 InCl 5 ·H 2 O with/without Sb 3+ dopant at room temperature. The transformation between Cs 2 InCl 5 ·H 2 O and Cs 2 NaInCl 6 products is controlled by the concentration of eco-friendly NaCl, where excess Cl − and Na + ions play important roles in inhibiting In 3+ hydrolysis and promoting Cs 2 NaInCl 6 crystallization, respectively. The obtained Cs 2 NaInCl 6 :Sb and Cs 2 InCl 5 ·H 2 O:Sb exhibit highly luminescent self-trapped exciton-related blue (450 nm; photoluminescence quantum yield [PLQY] ≈85%) and yellow (610 nm; PLQY ≈88%) emissions, which are comparable to those obtained by previous methods. Tunable cold/warm white light with a PLQY of up to ≈73% is achieved by the rational assembly of two components with highly overlapped excitation wavelength ranges. Each component demonstrates remarkable stability against humidity and heat. This composite shows great potential in solid-state lighting for general illumination.