Synthesis and luminescence properties of Mn-doped Cs₂KBiCl₆ double perovskite phosphors

Novel lead-free double perovskite phosphors of Mn-doped Cs₂KBiCl₆ (Cs₂KBiCl₆:Mn²⁺) have been facilely synthesized by using typical hydrothermal method. X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy, electron paramagnetic resonance, and photoluminescence measurements confirm that the synthesized Cs₂KBiCl₆:Mn²⁺ phosphors behave double perovskite structure, good morphology, excellent stability, and superior optical properties. An optimal doping concentration of Mn/Bi = 0.4 is achieved in Cs₂KBiCl₆:Mn²⁺ phosphors, showing maximum photoluminescence quantum yield of 87.2%, lifetime of 0.98 ms, and orange-red fluorescence with the emission peak at 595 nm under UV light excitation. The probable luminescence mechanism could be ascribed to excitation energy transferring from Cs₂KBiCl₆ to Mn, and accordingly contributing to the ⁴T₁-⁶A₁ transition of the Mn d electron. Superb optical properties provide much room for in-depth fluorescence researches and potential applications of Cs₂KBiCl₆:Mn²⁺ phosphors.